PROFET™ +24V - Short introduction to PROFET™ +24V

Application Note
PROFET™ +24V
Short introduction to PROFET™ +
24V
What the designer should know
Application Note
Rev 0.3, 2014-10-30
Body Power
App. Note
1
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2
2.1
2.2
2.3
2.4
Introduction. Why High Side Switches. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Short Circuit Hazard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
System Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Galvanic Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Other Switching Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3
3.1
3.2
3.3
3.4
3.5
Type of supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Module un-powered during stand-by . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Module supplied during stand by . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Left/Right Front/Rear separation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Secondary Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ground line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11
11
11
11
12
13
4
4.1
4.1.1
4.1.2
4.1.3
4.1.4
4.1.4.1
4.1.4.2
4.1.5
4.1.5.1
4.1.5.2
4.1.6
4.1.7
4.1.8
4.2
4.2.1
4.2.2
4.3
4.4
4.4.1
4.4.2
4.4.3
4.4.4
Truck Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Battery Voltage Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Alternator Regulation Loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Alternator Ripple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Start-Stop Application. Regenerative Braking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Low Battery Voltage Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Discharged Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Ignition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
High Battery Voltage Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Jump Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Load Dump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reverse Polarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Loss of Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A Good Reference for Battery Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ambient Module Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Internal Module Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lifetime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Running Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stand-by Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Number of Ignition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Number of Kilometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15
15
15
16
16
17
17
17
18
18
18
19
19
19
20
20
21
21
21
22
22
22
22
5
5.1
5.1.1
5.1.2
5.1.3
5.1.4
5.1.5
5.2
5.2.1
5.2.2
5.2.3
5.3
5.3.1
5.3.2
5.3.3
Load and Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lamps / Capacitive and Resistive Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lamps Regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lamp Wattage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cold Lamp / Inrush Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Life Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Light intensity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Light Emitting Diode (LED) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Standard LED Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Advanced LED Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LED Cluster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inductive Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Demagnetization Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Freewheeling Diode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23
23
24
24
24
25
25
26
26
27
27
28
28
29
29
Application Note
Smart High-Side Switches
2
Rev 0.3, 2014-10-30
App. Note
5.4
5.5
5.5.1
5.5.2
5.6
Number of Activations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wire as a Parasitic Electrical load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maximum Current in a Wire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Platform and Vehicle Diversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
29
30
30
30
31
6
6.1
6.2
6.3
6.4
Failures in the Field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Short Circuit to Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Short Circuit to Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Open Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Short Circuit Between Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
32
32
33
34
34
7
7.1
7.2
7.3
7.4
7.5
7.6
7.6.1
7.6.2
7.6.3
7.7
7.7.1
7.7.2
7.7.3
7.8
7.8.1
7.8.2
7.8.3
7.8.4
7.8.5
Power Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Voltage Limitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Charge Pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Slope Control Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Losses Calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Switch Behavior with PWM Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PROFET™ +24V PWM Limitations due to Power Losses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PROFET™ +24V usage in 12V system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PROFET™ +24V PWM Limitations Due to Switching Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Thermal Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maximum Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maximum Case Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maximum Power in PROFET™ +24V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inverse Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Capacitive Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output wired to Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inductive Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Alternator Ripple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Consequences for PROFET™ +24V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
35
35
36
37
37
38
40
40
41
42
43
43
43
43
44
44
45
45
45
45
8
8.1
8.2
8.2.1
8.2.2
8.2.3
8.2.4
8.2.5
8.2.6
8.2.7
8.2.8
8.3
8.4
8.5
8.6
8.7
8.7.1
8.7.2
8.7.3
8.7.4
Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Band gap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Short Circuit to Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PROFET™ +24V Current Limitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PROFET™ +24V Current Limitation Concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Temperature Swing Limitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maximum Temperature Limitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Restart Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PROFET™ +24V Life Time Limitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Activation Limitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Short Circuit to GND with Long Wire Harness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Short Circuit to Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Open Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Loss of battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Short Circuit Between Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Undervoltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Switching Capability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ignition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Low Battery Voltage Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
47
47
47
47
48
49
50
50
50
51
53
54
55
55
56
57
57
57
58
58
Application Note
Smart High-Side Switches
3
Rev 0.3, 2014-10-30
App. Note
8.8
8.8.1
8.8.2
8.9
8.9.1
8.9.2
Overvoltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Jump Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Load Dump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reverse Polarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Loads with Symmetrical Polarity Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reverse Polarity Protection for the Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
59
59
59
60
60
61
9
9.1
9.2
9.2.1
9.2.2
9.2.3
9.3
9.3.1
9.3.2
9.4
9.4.1
9.4.2
9.5
9.6
9.6.1
9.6.2
9.6.3
9.7
9.7.1
9.7.2
9.7.3
9.8
Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Current Sense . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gate Back Regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Influence on the Power Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sense Accuracy Improvement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sense Resistor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Short Circuit to Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Short Circuit to Ground in OFF State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Short Circuit to Ground in ON State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Short Circuit to Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Short Circuit to Battery in OFF State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Short circuit to Battery in ON State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inverse Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Open Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Open Load in OFF State with Bulb and Inductive Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Open Load in OFF State with LED Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Open Load in ON state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Partial Loss of Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Partial Loss of Load during OFF state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Partial Loss of Load during ON state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Current Sense Accuracy Improvement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Current Sense and PWM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
63
63
64
64
64
65
65
65
65
66
66
66
66
67
67
68
68
69
69
69
70
71
10
10.1
10.1.1
10.1.2
10.1.3
10.1.4
10.2
10.2.1
10.2.2
10.2.3
10.2.4
10.3
10.3.1
10.3.2
10.3.3
The Micro Controller Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GND Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GND Resistor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GND Diode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Different Ground for One System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Loss of Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Digital Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Absolute Maximum Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
High level input voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Undefined region . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Low level input voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sense Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maximum Load Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Minimum Load Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sense Pin Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
73
73
73
73
74
74
74
75
76
77
77
78
78
80
80
11
11.1
11.2
PROFET™ +24V Flexibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Pinout Logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Single and Dual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
12
12.1
12.2
PROFET™ +24V Scalability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Family Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Comparison Between Truck and Car Family . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Application Note
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App. Note
13
13.1
13.2
Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
PWM Power Losses Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Open Load Resistor Calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Application Note
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App. Note
Abstract
1
Abstract
Note: The following information is given as a hint for the implementation of the device only and shall not be
regarded as a description or warranty of a certain functionality, condition or quality of the device.
This Application Note is intended to provide useful information to designers using PROFET™ +24V high side
power switch in the truck, marina and commercial vehicle environment as well as industrial, commonly reduced to
truck applications. As the Appnote is based on the equivalent PROFET+ 12V, it highlights main differences
between the two applications and main differences between products, helping the read out.
Starting from a design perspective, the Application Note describes the application requirements and conclude at
device level.
Table 1
Terms in use
Abbreviation
Meaning
A/D
Analog to Digital converter
AWG
American Wire Gauge
BCM
Body Control Module
CP
Charge Pump
KL15
So called for battery voltage turned OFF during park time of the vehicle
KL30
So called for battery voltage always present
KL58
So called for the battery voltage to the instrument cluster
CHMSL
Central High Mounted Stop Light
DMOS
Double diffused MOS
DRL or DTRL
Day Time Running Light
ESD
Electro Static Discharge
EMC
Electro Magnetic Compatibility
EME
Electro Magnetic Emission
EMI
Electro Magnetic Immunity
ECU
Electronic Control Unit
E²Prom
Electrically Erasable Programable Read Only Memory.
GND
Ground
GBR
Gate Back Regulation
GPIO
General Purpose Input Output
HSS
High Side Switch
I/O
Input Output (of a digital circuit)
IN
Input
ISC
IL(NOM)
kilis
Short circuit current
LED
Light Emitting Diode
LSS
Low Side Switch
mission profile
Represents the life cycle of the vehicle, in terms of time, temperature, supply and hazard.
MOSFET
Metal Oxide Silicon Field Effect Transistor
OL
Open Load
Nominal current
Load current mirror factor
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App. Note
Abstract
Table 1
Terms in use
Abbreviation
Meaning
[email protected]
Open Load in OFF state
[email protected]
Open Load in ON state
OEM
Original Equipment Manufacturer. In this document, vehicle maker
OC
Over current
OT
Over temperature
OTS
Over temperature swing
OL
Open load
PROFET
Protected FET
PWM
Pulse Width Modulation
PLAMP
Lamp power, expressed in Watts.
PCB
Printed Circuit Board
RDS(ON)
Resistance of the channel during ON state
RPM
Revolution Per Minutes
SC
Short Circuit
Tier1
Supplier of the ECU to the OEM:
TA
TC
TJ
Ambient temperature
USM
Under hood Switching Module
VDD
VBAT
VS
ZSC
Micro controller supply voltage
Case temperature, or temperature of the solder
Junction temperature
Battery voltage, measured at the battery terminal
Supply voltage of the device, usually battery voltage
Short circuit impedance
Application Note
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App. Note
Abstract
ECU 1
Electronic Control Unit
LED
Lamp
Internal Device Signal
Generic Load,
component C, L and
R not 0
Internal Device GND
CHASSIS POTENTIAL
ECU Connector
FUSE
Current source
SWITCH
VBAT
CABLE
Battery
Alternator
Lead Battery
VBAT
Alternator with 3
phases winding
OUT
GND
Represents the physical
point of entrance in
device or ECU
drawing and meaning.svg
Figure 1
Drawing and Convention
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App. Note
Introduction. Why High Side Switches.
2
Introduction. Why High Side Switches.
In the truck system, a single electrical supply VBAT potential is available. Five possible solutions exist (refer to
Figure 2) to switch electrical loads ON and OFF. The truck engineering community defines High Side Switches
as a switch commuting the battery voltage.
VBAT
VBAT
LOW SIDE
HIGH SIDE
VBAT
VBAT
PUSH PULL
HALF BRIDGE
VBAT
VBAT
H BRIDGE
SERIAL
commutation possibility of a load .vsd
Figure 2
Commutation Possibility of a Load
High Side Switches are used worldwide in automotive applications. Two reasons justify this choice, Short Circuit
hazards and System Cost.
2.1
Short Circuit Hazard
A Short Circuit (SC) hazard is more likely to occur to GND than to the battery voltage VBAT, thus switching from
the high side is considered safer than switching from the low side. Figure 3 represents all possible short circuits
in a truck electrical system. The SC in green will result in the load being permanently ON load. The SC in orange
will result in stress to the switch. The SC in red will place stress on the complete vehicle electrical system
VBAT
Battery
SHORT CIRCUIT
TO BATTERY
SHORT CIRCUIT
GND
ECU
HSS
OUT
SHORT CIRCUIT
TO GND
VBAT
SHORT CIRCUIT
TO GND
Battery
SHORT CIRCUIT
TO GND
ECU
LSS
SHORT CIRCUIT
TO BATTERY
OUT
SHORT CIRCUIT
TO GND
Short circuit .vsd
Figure 3
Short Circuit Possibility
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App. Note
Introduction. Why High Side Switches.
2.2
System Cost
A Low Side Switch, compared with an equivalent (same package and RDS(ON) class) High Side Switch is cheaper.
Nevertheless, at system level, using High Side Switches architecture is more cost effective. Figure 4 shows a
comparison between the 2 architectures. A LSS architecture will usually require an additional wire and fuse for
protection.
Fuse box
VBAT
GND
ECU
Battery
µC and
LOGIC
HSS
Fuse box
VBAT
GND
ECU
Battery
µC and
LOGIC
LSS
System cost comparison .vsd
Figure 4
System cost comparison
2.3
Galvanic Corrosion
High Side is often preferred to low side switch while in OFF state there is no battery voltage present at the load.
With voltage present at the load along with humidity and time a bi-metal galvanic corrosion can occur at the
connector for the load. Since High Side does not have voltage present at the during OFF state the amount of
corrosion is much less.
2.4
Other Switching Solutions
Low side switches are mainly used in applications where one main switch protects several loads switched using
the low side.
Push-Pull switches are used in applications which require only one way of current and a very quick deactivation.
This architecture includes one HSS. Typical loads include the windshield wipers.
An H-Bridge is the most common method to drive bi-directional motors. Two HSS are used in this architecture.
Serial switching is used where a single failure (such as a short circuit to GND) would cause a critical safety problem
e.g. turn the load ON when not acceptable. Typical applications include the Airbag squibs and critical valves. One
HSS is used in this architecture.
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App. Note
Type of supply
3
Type of supply
3.1
Module un-powered during stand-by
Figure 5 shows a typical application where the ECUs are de-powered when the vehicle is parked with the engine
off. This type of battery supply is commonly called KL15 (eg in Germany) or Terminal 15.
KL15
relay
Relay driver
KL15
ECU1
KL15
ECU2
KL15
ECU n
KL15
Battery
Energy Distribution
ECU m
KL15 topology.vsd
Figure 5
Clamp 15 application
3.2
Module supplied during stand by
Figure 6 shows a typical application where the ECUs remain powered when the vehicle is parked with the engine
off. This type of battery supply is commonly called KL30 (eg in Germany) or Terminal 30.
Energy Distribution
KL30
ECU1
KL30
ECU2
KL30
ECU n
KL30
ECU m
Battery
KL30 topology.vsd
Figure 6
Clamp 30 application
3.3
Left/Right Front/Rear separation
For safety reasons, supply redundancy is often necessary. Redundancy of the supply is often based on the
separation of the left and right side of the vehicle. This is where one battery line supplies all loads on the left side
of the vehicle and another line supplies all loads on the right side. The same redundancy can be found with front
and rear separation. Adding to this the KL15 and KL30 concepts, a complex ECU can be supplied by up to 8
different supply lines. Figure 7 shows such a supply architecture.
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App. Note
Type of supply
3.4
Secondary Supply
Some modules also provide a secondary supply to sub-systems. This architecture is common in door modules
and climate systems which can be supplied by a dedicated battery feed switched from the master door or climate
ECU. Typical example is the KL58 supply line used to supply the dashboard.
ECU
Supply with
Front battery
feed
ECU
Supply with all
battery feed
ENERGY DISTRIBUTION BOX
KL 15L_F
KL 15R_F
KL 30L_F
KL 30R_F
KL 30L_R
KL 30R_R
KL 15L_R
KL 15R_R
Battery
ECU with
single battery
feed.
OFF in park
mode
ECU with
dual battery
feed.
ECU with all
battery feed,
unsupplied in
Park
Left Right Front Rear.svg
Figure 7
Complex and Mixed of supply line architecture
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App. Note
Type of supply
3.5
Ground line
The ground (GND) in a truck is the negative point of the battery or alternator. Therefore, GND is of difficult access
and which needs harness. Refer to the Figure 9. In most cases, there is at least one GND pin per module
connector. This GND pin is connected via a wire. Figure 8 shows different ways to realize a GND connection. On
the left hand side is the cheapest method. The most expensive but safest and recommended method is shown on
the right and side.
ECU
ECU
ECU
ECU
Ground line .vsd
Figure 8
Ground Line Concept
BATTERY
G
ECU
ECU
ECU
Ground line - Truck.vsd
Figure 9
Ground Line Example in a Truck
One consequence of this architecture can be that some modules don't have the same 0V (GND) reference. For
example (refer to Figure 10) a high current application such as power steering, starter motor or alternator doesn't
have the same 0V reference as the rest of the vehicle. This can also be the case for applications where the
connecting cable to GND is long or thin, causing a noticeable impedance. This ground shift voltage can be either
positive or negative. Infineon recommends ISO11898-3 (Low Speed CAN network ISO norm) as a good reference.
This standard specifies a ±1.5V between ECU GND and chassis GND.
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App. Note
Type of supply
Phase 1
µC
Phase 1
LDO
VBAT
e.g
Phase 2
XC2200
Phase 3
3
phases
Motor
Three phase
motor driver
Phase 2
e.g
TLE7185 E
IPB80N04S3-02
Phase 3
PCB traces
impedance
E.g 80A
GND
+
V SHIFT
-
E.g 80A
Ground shift high power .vsd
Figure 10
Typical high current application
To simplify this application note, vehicle GND and ECU GND will be considered the same, except where explicitly
mentioned. The appropriate terminology is ground shift voltage however this is commonly referred to as simply
ground shift. Ground shift represents the difference, VSHIFT between the 0V reference of the ECU and the real 0V
of the load. Refer to Figure 11.
VBAT
OUT
GND
+
VSHIFT
-
Ground shift .vsd
Figure 11
Ground shift description
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App. Note
Truck Environment
4
Truck Environment
4.1
Battery Voltage Supply
Only one supply potential, VBAT is available in the vehicle. This supply comes from the battery when the engine is
off and from the alternator when the engine is running. Figure 12 shows the typical supply topology. The battery
voltage is typically 24V (engine off) and 28V when the engine is running although this figures are different for
different OEMs. These values can vary in different phases of the mission profile. For simplicity, VBAT will be used
for both the real battery voltage and VALT, the alternator voltage (engine running).
Relay and
Fuse box
VBAT
ECU
V S30L
CL30 Left
V S30R
V S15L
CL30 Right
CL15 Left
CL15 Right
V S15R
V S58d
CL58
Battery
Alternator
GND
GND
Supply chain .vsd
Figure 12
Typical Supply Chain in a Vehicle
4.1.1
Alternator Regulation Loop
The alternator provides current as soon as the engine reaches idle (typically 300RPM). If there is no diode or
battery to limit the voltage, an alternator can provide a voltage of greater than 100V. The current the alternator can
provide is between 55A and 200A. This value is mainly dependant on the engine RPM and engine cooling. The
alternator current rating is defined by the total vehicle load. The regulation voltage is specified as a function of the
alternator temperature (TALT). The voltage usually decreases with temperature such that the maximum battery
voltage is reached when TALT is -40°C. Refer to Figure 13.
33
Regulation Voltage (V)
(V)
31
29
27
25
23
-40
-10
20
50
80
Alternator temperature (°C)
Figure 13
110
140
alternator regulation loop _truck .vsd
Alternator Regulation Voltage Function of Temperature
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App. Note
Truck Environment
4.1.2
Alternator Ripple
When the alternator is heavily loaded and providing its maximum possible current, the ripple on the supply line
cannot be neglected. VBAT looks similar to Figure 14. The frequency fAR and the voltage swing depends on the
OEM. As a good reference, the following figures may be used: VAR = 3V peak to peak, fAR = [1kHz; 20kHz].
17,0
f AR
16,5
16,0
Alternator Voltage (V)
15,5
15,0
VAR
14,5
14,0
13,5
13,0
12,5
12,0
0
250
500
750
1000
Time (µs)
1250
Figure 14
Typical Alternator Ripple Voltage as a Function of Time
4.1.3
Start-Stop Application. Regenerative Braking
1500
1750
alternator ripple .vsd
The alternator can be a starter-alternator and it can also be used to realize regenerative braking. Each time the
truck is stationary, the engine is stopped. Engine restart strategies vary between OEMs however the most
common method is when the driver releases the brake pedal. This restart will be called in the document “hot start”,
in contrario to “cold start” when the truck driver turn the ignition key.
A significant increase in "hot start" starts needs to be considered. A typical figure is 30 "hot start" starts per "cold
start" start. Since the ignition phase is a severe power consumer (200A for hot ignition, 1000A for cold ignition), it
is necessary to recharge the battery quickly. This can be achieved by increasing VBAT artificiality. Typically to 36V.
An increase in VBAT results in an increase in electrical power. This increases the engine resistive torque and hence
engine gas consumption also increases. This is not acceptable except during braking when kinetic energy is
converted into electrical energy.
During acceleration, the resistive alternator torque can be too high and the alternator can be turned OFF during
severe acceleration. Figure 15 shows the shape of the battery supply voltage, assuming a starter-alternator with
regenerative braking.
As an example, a 28V regulated alternator providing 70A DC current corresponds to 2kW electrical power.
Assuming 30% efficiency, the mechanical energy required to provide this 2kW of electrical power is 6.4kW or 8
horse power (PS). Taking a standard 250PS engine, the driven alternator can offer up to 5% power increase.
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App. Note
Truck Environment
Truck speed
t
VBAT
36V
28V
24V
t
driven alternator _truck .vsd
Figure 15
Battery Voltage as a Function of Vehicle Speed.
4.1.4
Low Battery Voltage Supply
Low voltage supply phases can be either due to a weak battery (discharged) or during engine cranking. The weak
battery is a permanent state (from a semiconductor perspective) while cranking is a transient phenomenon.
4.1.4.1
Discharged Battery
A discharged battery is usually due to parasitic leakage current in the vehicle when it has been parked for too long.
The minimum battery voltage at which the vehicle can still start is OEM dependant. This voltage is considered as
the minimum nominal voltage. Typically 16V.
4.1.4.2
Engine Ignition
The voltage during the ignition phase is complex to describe and the values are very dependant on the vehicle
OEM as well as the type of engine. All OEMs specify different ignition voltage pulses VCRK_MIN from 8 to 12V (refer
to Figure 16). VCRK_OSC is usually 16V and oscillations range from a couple of Hertz to 800Hz (300RPM). VBAT_STD
is the battery voltage during the engine stand-by phase and is usually 24V. VBAT_RUN is the battery voltage when
the engine is running and is usually 28V. For simplicity the red curve is used with VCRK_MIN = 8 to 12V, typically
10V. tCRK = 65ms, tLAUNCH = 10s and VCRK_LAUNCH = 12 to 16V.
Thanks to the relative high voltage, cranking is not an issue in truck application.
Application Note
Smart High-Side Switches
17
Rev 0.3, 2014-10-30
App. Note
Truck Environment
VBAT
VBAT_RUN
VBAT_STD
VCRK_OSC
VCRK_LAUNCH
VCRK_MIN
t CRK
t LAUNCH
t
Cranking pulse .vsd
Figure 16
Ignition pulse
4.1.5
High Battery Voltage Supply
The reasons behind a high battery voltage are more numerous than a low battery voltage and include jump start,
load dump, faulty alternator regulation and high alternator ripple.
4.1.5.1
Jump Start
The jump start for a truck(24V) is a situation where a welding machine (48V) is bypassing the battery to start the
engine. The voltage and the time of the jump start is OEM dependant. A worst case is 48V for 15 minutes.
4.1.5.2
Load Dump
Load dump occurs when the battery terminal is suddenly disconnected while the alternator is providing current.
The battery is essentially a capacitor and hence stabilizes the system. Load dump can also occur during the
switching of high current inductive loads. Refer to Figure 17. When the battery is disconnected, the system
becomes unstable and the voltage rises until the alternator low side diodes reach avalanche, limiting the voltage
to Vloaddump. Some OEMs replace the diodes with Zener diodes. The advantage Zener diodes provide is to reduce
the load dump (avalanche) voltage to the Zener voltage. Vloaddump and tloaddump are specified by the OEM. After a
delay, (tloaddump) the alternator begins to regulate again and the voltage decreases. As a good reference, Infineon
consider Vloaddump = 58V for tloaddump = 400ms. After the load dump event, a high ripple voltage is observed on the
battery line while the battery remains disconnected. As a good reference, Infineon consider VALT_MAX = 36V and
VALT_MIN = 24V. The oscillation frequency is considered to be between 1kHz and 20kHz and can be up to 10 hours
long. Refer to Figure 18.
Application Note
Smart High-Side Switches
18
Rev 0.3, 2014-10-30
App. Note
Truck Environment
VBAT
ECU
Vd
Battery
Vloaddump
Id
Alternator
GND
VAZ(DIODE )
Load dump
configuration . vsd
Figure 17
Load Dump Configuration
VBAT
Vloaddump
VALT_MAX
VBAT_RUN
VALT_MIN
Figure 18
Load Dump Pulse
4.1.6
Reverse Polarity
tloaddump
Load dump pulse .vsd
t
A Reverse polarity condition exists when the battery supply line VBAT is connected to ground and the ground line
GND to the battery supply. Reverse polarity mainly occurs for two reasons. During the module handling and
installation, where some awkward movements can be assumed, or when the vehicle has a low battery and the
driver connects jumper cables incorrectly from an external battery (Start help), reverse polarity can result. The
voltage and time for which the vehicle can withstand this reverse polarity is defined by the OEM. As a good
reference, Infineon considers -28 V for 1hour at ambient temperature +25°C. Some loads such as a lamp or
resistor can tolerate current flowing in the reverse direction whilst others cannot such as motors, polarized
capacitors, etc...
4.1.7
Loss of Battery
In an architecture such as KL15, loss of battery is a normal case. In an architecture with shared fuse, when the
fuse blows due to a short circuit somewhere else, the loss of the supply line should not result in a module failure.
4.1.8
A Good Reference for Battery Voltage
To sum up the above discussion, refer to Figure 19.
Application Note
Smart High-Side Switches
19
Rev 0.3, 2014-10-30
App. Note
Truck Environment
Reverse
battery
OFF
-28V
0V
2min ...1h 80khours
25°C [-40°C;150°C]
Cranking
8...12V
65ms
-40°C
Nominal battery voltage
16V
50k hours
[-40°C;150°C]
Jump start
36V
50khours
[-40°C;150°C]
Load dump
48V
15min
25°C
58V
400ms
25°C
Battery voltage
range _truck .vsd
Figure 19
Infineon Good Reference for Battery Voltage
4.2
Temperature
The ambient temperature TA range in an automotive application is one of the harshest found in electronics. Only
space and aeronautical activities can be more challenging. If the minimum temperature is universally agreed to be
-40°C, the maximum temperature varies with applications, OEM, tier1, module housing, etc.. As a good reference,
Infineon considers TA_MAX = +85°C for cockpit application, TA_MAX = +105°C for under hood application.
4.2.1
Ambient Module Temperature
Ambient module temperature follows the seasons as shown in Figure 20. Ambient module temperatures are cold
in winter, hot in summer. While -40°C is considered to be the minimum temperature to start the truck in winter, it
is not valid for every engine start in winter as the system heats up during driving. The same logic can be applied
to the hot season. It is possible to assume +85°C or +105°C for example, as the maximum ambient temperature
(truck parked in summer) at start up, but it is incorrect to assume that TA_MAX = +85°C is a permanent condition
during summer. In other words, -40°C and +85°C are considered as starting points, but not as permanent
conditions. As a good reference, Infineon considers an ambient temperature profile shown in Figure 21.
TA
TA_ MAX
TA_typical
TA_MIN
January
March
June
September
December
time
temperature over one year .vsd
Figure 20
Suggested Ambient Module Temperature, over one Year
Application Note
Smart High-Side Switches
20
Rev 0.3, 2014-10-30
App. Note
Truck Environment
Temperature
repartition
TA MAX
TA typical
-40°C
TA
temperature repartition .vsd
Figure 21
Suggested Temperature Distribution over Vehicle Life Time
4.2.2
Internal Module Temperature
The devices, soldered on the PCB, are subject to the heat radiated by neighboring devices. Each module design
is different, hence the heat generated is dependent on the design of the module. As a good reference, Infineon
considers a self heating of the module of +15°C in operation mode.
4.3
Ground
As described in Chapter 3.5, a ground shift VSHIFT can exist between the module ground and device ground.
Loss of ground should also be a consideration in module design. There are two possible failures which can cause
loss of ground, loss of device ground and loss of module ground. Refer to Figure 22. As a device supplier, Infineon
assumes any loss of ground to be loss of device ground unless explicitly indicated.
VBAT
ECU
VS
Voltage
regulator
Micro
controller
GND
HSS
LOSS OF DEVICE
GROUND
LOSS OF MODULE
GROUND
Loss of ground .vsd
Figure 22
Loss of Module or Device Ground
4.4
Lifetime
The life time of one truck / module / device is assumed to be 15 years or 131400 hours.
Application Note
Smart High-Side Switches
21
Rev 0.3, 2014-10-30
App. Note
Truck Environment
4.4.1
Running Time
Running time is an accumulation of time over which the module is in operation (micro controller active, load
activated or ready to be activated) is assumed to be 50,000 hours. (~8 hours per day for 15 years)
4.4.2
Stand-by Time
Stand-by time corresponds to the remaining time over 15 years where the module is not in operation. With the
above assumptions, this is 81,400 hours.
4.4.3
Number of Ignition
The number of ignitions cycles is determined by the strategy of the vehicle OEM. As a good reference, Infineon
consider 100 000 cold ignitions over the vehicle life time. This leads to almost ~20 (18.6) ignitions per day. This
number doesn't include the additional start and stop cycles due to the future introduction of starter-alternators. 30
hot ignitions are considered per cold ignition.
4.4.4
Number of Kilometer
The number of kilometers are estimated to be 2,000,000km during life time or 30,000 km a month. For the truck
trailer, the figures are doubled so 4,000 000 km during life time and 60,000km a month.
Application Note
Smart High-Side Switches
22
Rev 0.3, 2014-10-30
App. Note
Load and Application
5
Load and Application
The diversity of loads driven by high side switches is enormous. To cluster these loads is always challenging.
Nevertheless, three different categories can be outlined. Lamps or capacitive loads, Motors or inductive loads, and
LED or resistive loads.
5.1
Lamps / Capacitive and Resistive Loads
Switching lamps for exterior lighting always have been the major application of HSS. By law, in every country, 20
lamps covering 8 different functions must be implemented in a vehicle. Table 2 lists the required lighting including
the minimum wattage.
Table 2
N°
1)
Lamps Required by Law
Function
Abbreviation
Number of Load
Position
Minimum wattage
1
Brake light
STOP
3
Rear
22) x 2 x 21W
2
Park light
PL
4
2 Front, 2 rear
4x5W
3
Licence plate
LIC
1
Rear
1x5W
4
Fog
FOGR
1
Rear
22) x 1x21W
5
Reverse light
REV
1
Rear
2 x 2)1x21W
6a
Side indicators left
SI
3
1 Front, 1 center, 1 rear 1 x 21W +22) x 21W
+ n3) x 5W
6b
Side indicators right
SI
3
1 Front, 1 center, 1 rear 1 x 21W + 22) x 21W
+ n3) x 5W
7
Low beam
LB
2
Front
2 x 70W
8
High beam
HB
2
Front
2 x 70W
1) The number is arbitrary
2) Twice to have the function on the tractor and on the trailer
3) n is proportional to the truck length / 3m (one repeater every 3m)
Additional lamps are often present. Table 3 provides a list of the more common optional lamps. On modern
vehicles there are typically up to 40 lamps covering more than 14 functions
.
Table 3
N°
1)
Optional Lamps
Function
Abbreviation
Number of Load
Position
Wattage
2
Park light
PL
4
2 Front, 2 rear
4x5W
3
Licence plate
PP
1
Rear
1x5W
10
Side marker
SM
2
Center
2x5W
4
Fog
FOGR
1
Rear
1x21W
5
Reverse light
REV
1
Rear
1x21W3)
11
Fog
FOGF
2
Front
2x70W
12
Interiors
INT
From 1 to 10
Interior
From 1x5W to 100W
13
Cornering lamp
CL
2
Front
2x70W
14
Daytime Running
Light2)
DRL
2
Front
2x21W
15
5th wheel
5th
2
Front
2x70W
1) The number is arbitrary
Application Note
Smart High-Side Switches
23
Rev 0.3, 2014-10-30
App. Note
Load and Application
2) Required by law in some countries, can be realized with Low Beam
5.1.1
Lamps Regulation
The United Nation Organization (UNO) has regulated automotive lamps in terms of mechanical structure, light
emission power and electrical power. These regulations can be found at UNO under the title "Agreement
concerning the adoption of uniform technical prescription for Wheeled vehicles, equipment and parts which can
be fitted and/or used on wheeled vehicles and the conditions for reciprocal recognition of approvals granted on
the basis of these prescriptions". The reference numbers are E/ECE/324 and E/ECE/TRANS/505, dated October
19, 2001. This document is considered the good reference of Infineon in terms of lamp wattage.
5.1.2
Lamp Wattage
The lamp wattage is defined at a specific voltage with a percentage tolerance. Table 4 shows the most commonly
used lamps in terms of electrical wattage, tolerance and voltage.
The lamp current is dependent on the supply voltage VLAMP. Equation (1) gives the current, function of VLAMP,
supply voltage of the lamp. VREF is the voltage where the power of the lamp is defined.
I LAMP =
5.1.3
V LAMP P LAMPREF
----------------- × ------------------------V REF
V REF
(1)
Cold Lamp / Inrush Current
Before switch ON, the lamp is cold. To produce light, it is necessary for the lamp filament to reach a very high
temperature (above 1000°C). At switch ON, a significantly higher current is flowing in the filament. This current is
called inrush current IINRUSH. Depending on the OEM or tier1 manufacturer, a certain ratio is applied which relates
the nominal current of the lamp to the inrush current. As a good reference, Infineon considers an inrush factor of
15x. Figure 23 shows an ideal 21W bulb inrush current without any system limitation. Inrush current increase while
temperature decreases.
There is an inherent time required to turn the lamp ON which is defined as tLAMP_ON. Due to the inrush current, the
lamp turn ON time, tLAMP_ON cannot be defined unambiguously. As a good reference, Infineon considers the lamp
is ON when the load current reaches 50% of the IINRUSH, the last retry in case of retry. Infineon considers suitable
a switch which allows a tLAMP_ON < 30ms.
Table 4
Electrical Wattage Lamp
Lamp
W
Accuracy
%
VREF
5
10
10
V
Max DC current
in A1)
Max Inrush Max PWM current
in A
A2)
Maximum current
A3)
27
0.2
3.5
0.4
0.6
10
27
0.5
7.0
0.7
1.3
21
6
24
1.1
17.0
1.7
3.0
70
6
27
2.9
44.0
4.4
7.8
1) At 36V
2) At 36V with light emission regulation (with duty cycle calculated in Chapter 5.1.4)
3) At 36V with 2% PWM
Application Note
Smart High-Side Switches
24
Rev 0.3, 2014-10-30
App. Note
Load and Application
70
IDS (A)
Vbulb (V)
60
I INRUSH
IL (A) and VL [V]
50
50% IINRUSH
40
30
20
t LAMP_ON
t LAMP_ON
10
0
0
0,005
0,01
Time [s]
Figure 23
Ideal Inrush of a Lamp
5.1.4
Life Time
0,015
0,02
Bulb inrush .vsd
The life time of a lamp is dependent on several parameters with one of the most critical being the supply voltage.
As a rule of thumb there is a life time reduction of 50% per volt increase for supply voltages above 24V . Ideally,
a constant supply voltage should be provided to the lamp. The cost of such a solution is prohibitive, in practice this
strategy is never implemented.
Another approach is to use Pulse Width Modulation to drive the lamp. The basic idea of PWM is to maintain
constant power in the lamp. The trick is to use the filament thermal inertia to absorb the PWM waveform, making
it invisible to the human eye. The larger the wattage, the bigger the thermal inertia so the PWM waveform can be
lower in frequency. The PWM duty cycle is calculated using Equation (2), VPWM is the optimum lamp voltage.
2
V PWM
d = -------------------2V LAMP
(2)
Typically values are VPWM = 24 V in Europe .
5.1.5
Light intensity
The intensity of the light is linked to the lamp supply voltage. The aim is to minimize the light intensity fluctuation,
which is a function of the battery voltage. The PWM duty cycle, derived from the battery voltage measurement has
to be refreshed fast enough to eliminate light fluctuation. However a simple modification of the duty cycle
corresponding to a spike in battery voltage is not acceptable. A software strategy should be implemented to
leverage the battery voltage as for example Equation (3).
(VBAT(t) corresponding to the measured VBAT at the given quantum t)
V BAT ( t – 2 ) + V BAT ( t – 1 ) + V BAT ( t )
V BAT ( t ) = --------------------------------------------------------------------------------------------3
(3)
With this strategy, the system is able to react in a maximum of tMAX which is equal to three time t sample µC, the micro
controller sample period. tMAX is given by the OEM. As good reference, Infineon consider tMAX = 30 ms.
Figure 24, is an example of PWM voltage regulation to 24V. These graphs show the worst case scenario when
fluctuations in the battery voltage occur just after a battery measurement.
VBAT is the real supply voltage of the system;
Application Note
Smart High-Side Switches
25
Rev 0.3, 2014-10-30
App. Note
Load and Application
d is the PWM duty cycle;
<VLAMP> matches the equivalent lamp voltage.
t sample µC
VBAT
32V
t MAX
28V
t
Duty cycle
tMAX
0.73
0.61
0.74
0.56
t
<VLAMP>
27V
24V
21V
t
PWM - truck.vsd
Figure 24
Reaction Time and Strategy for PWM
5.2
Light Emitting Diode (LED)
LEDs are increasingly being used to replace standard lamp bulbs. They offer a longer lifetime as well as lower
current consumption for an equivalent light intensity output. Two kinds of LED modules are often used, standard
and advanced. For the HSS designer, the difference between these 2 types of modules is negligible and they can
both be modeled as a resistive load. An advantage of a LED is that it starts to emit light, far much quicker than a
lamp, as soon as a voltage large enough to overcome the forward bias of the device is applied. This voltage
depends mainly on the LED color. A very small current (as a good reference, Infineon considers 10µA) is enough
to cause a LED to glow. This justifies the usage of the ROL_LED in case open load diagnosis is required.
5.2.1
Standard LED Module
In a standard LED module, when one LED is an open circuit, the other LEDs are not affected. This behavior is
particularly desirable for rear lighting. The standard LED module, shown in Figure 25 consists of a series resistor
RLED to limit the current and a cluster of LEDs in parallel and serial. The advantage of this circuit is the simplicity.
The drawback is the continuous power loss in the resistor (at least 500mW) and the susceptibility to transient over
voltages and currents. This kind of LED modules are often found for rear light system. As a good reference,
Infineon considers R LED = 50Ω, ROL_LED = 680Ω.
Application Note
Smart High-Side Switches
26
Rev 0.3, 2014-10-30
App. Note
Load and Application
IN
RLED
ROL_LED
OUT
Standard LED module.svg
Figure 25
Standard LED Module
5.2.2
Advanced LED Module
In an advanced LED module, when one LED is an open circuit, the entire module is OFF. This behavior is
particularly hazardous for headlights. The advanced LED module, shown in Figure 26 consists of a DC/DC
converter driving LEDs in serial. The advantage of this architecture is robustness and immunity to voltage
transients. The disadvantage is the relative electronic complexity of the DC/DC converter. As a good reference,
Infineon considers the module OFF if VIN - VOUT < 7V. When the LED is broken, the module doesn't consume more
than 30mA max, typically 15mA (current needed by the DC/DC supply itself).
IN
DC/DC e.g
TLD5095
ROL_LED
OUT
Advanced LED module.svg
Figure 26
Advanced LED Module
5.2.3
LED Cluster
The number of LED per string, and the number of string are application and OEM dependant. Nevertheless, a
rough estimation can be realized in Table 5
Table 5
LED cluster
Function
Number of string
Number of LED per string
Standard / Advanced
Brake light
7 to 10
1 to 3
Standard
Park light
2 to 5
1 to 3
Standard
Side indicators left
1 or 2
7 to 10
Advanced
Side indicators right
1 or 2
7 to 10
Advanced
Low beam
1 or 2
9 to 12
Advanced
High beam
1 or 2
9 to 12
Advanced
Side marker
2 to 5
1 to 3
Standard
Application Note
Smart High-Side Switches
27
Rev 0.3, 2014-10-30
App. Note
Load and Application
Table 5
LED cluster
Function
Number of string
Number of LED per string
Standard / Advanced
Front Fog
1 or 2
9 to 12
Advanced
Daytime Running Light
1 or 2
7 to 10
Advanced
5.3
Motors
There is often a requirement to drive a motor in both directions. The driver architecture must then be an H-bridge
where two HSS are used. Some motors always run in the same direction, such as wipers, water pump, etc hence
only a single HSS is required.
5.3.1
Inductive Load
Inductive loads are described by inductance L and resistance R. At switch ON, the inductive load causes a slow
current ramp up, based on the time constant τ = L/R. At switch OFF due to the inductance, the current attempts
to continue to flow in the same direction which causes the load voltage to invert. Refer to Figure 27, which
demonstrates the general voltage and current characteristics of an inductive load at switch ON and OFF. Voltage
in blue, current in red, power in green.
IL
7
VBAT
R
6
5
4
VBAT
3
2
1
0
0,00
500,00
0A line
1000,00
1500,00
2000,00
2500,00
-1
VOUT
VBAT
20
10
IL
+
0V line
0
- 10
L, R
VOUT
- 20
- 30
- 40
PLOSS
-
250
200
150
100
50
0W line
0
-50
Inductive load .vsd
Figure 27
Inductive Load Switch ON / OFF
Application Note
Smart High-Side Switches
28
Rev 0.3, 2014-10-30
App. Note
Load and Application
5.3.2
Demagnetization Energy
As stated previously, each time an inductive load is switched OFF, a demagnetization energy has to be
considered. If the over voltage protection limit is known, this demagnetization energy can be calculated according
to Equation (4)
V S – V DS ( AZ )
L
R×I
E = V DS ( AZ ) × ---- × --------------------------------- × ln ⎛ 1 – ---------------------------------⎞ + I
⎝
R
V S – V DS ( AZ )⎠
R
5.3.3
(4)
Freewheeling Diode
To keep the current running, and to get advantage of the stored energy in the coil, a freewheeling diode can be
used. In such a case, current and voltage in the switch appears as shown in Figure 28 describing a load of 195mH
and 7Ω. The PROFET™ +24V in use is the BTT6050-2EKA. The battery voltage VBAT is set to 32V. PWM is set
to 400Hz. From this example, it is observable that the power in the diode cannot be neglected.
Load Current (A)
VBAT
4,5
4
3,5
3
2,5
2
1,5
1
0,5
0
Load current
Load current without PWM
0
10
20
30
40
50
30
40
50
Time (ms)
IL
+
Power (W)
VOUT
-
L, R
1,4
1,2
1
0,8
0,6
0,4
0,2
0
Power losses in the diode
Power losses in the switch
0
10
20
Time (ms)
Freewheeling_24V.vsd
Figure 28
Voltage and Current Profile with Freewheeling Diode in PWM starting phase
5.4
Number of Activations
The total number of activations (brake pedal depressed, low beam activation, compressor activation, etc..)
depends largely on the habits of the vehicle driver. This does not including extra switching done by the ECU e.g.
PWM, software retry strategies etc... The exact mission profile is usually given by the OEM, but nevertheless loads
can generally be placed in one of five categories as defined in Table 6.
Application Note
Smart High-Side Switches
29
Rev 0.3, 2014-10-30
App. Note
Load and Application
Table 6
Load activations per engine ignition
N° of activation N° of activation Type of load example
per ignition
Average
activation time
N° of activation
per year
High
30
Brake light, Side Indicators
< 1mn
220 000
High
30
Low beam with automatic activation > 1mn
220 000
Mid
1 or 2
Reverse, Interiors lamp
> 1mn
15 000
Mid
1 or 2
Low beam with manual activation
> 1mn
15 000
Low
1/3
High beam, Fog lamps
> 1mn
2500
5.5
Wiring
To completely define a wire, three parameters are necessary, the diameter, the length and the insulator materials.
The diameter and length give the electrical characteristics (Ω / km and Lcable / km). The insulator and the
environment gives the maximum current.
5.5.1
Wire as a Parasitic Electrical load
Although the wire is not a load, it has to be considered in automotive applications during the design phase. Wires
offer a benefit to the system by limiting surge currents such as bulb lamp inrush current thanks to parasitic
inductance (Lcable), as well as resistive (RCABLE). The wire will limit the current. On the other hand, the inductive
energy stored in the cable is sometimes not neglectable, especially for long wire harness found in truck or trailer
application.
5.5.2
Maximum Current in a Wire
Wires require protection from excessive current. The maximum current which can flow in the wire is time
dependent and defined by a square law function I²t = constant. The maximum current the wire can handle is limited
by the insulation material. The OEM defines the wires to be used in a vehicle and this information is usually kept
confidential. Figure 29 shows an example of the current time coupling limitation of a cable as a function of the
time.
The maximum current in the wire is a thermal law. This constant depends, as previously stated on the insulation
material and also neighboring cables. For example, a wire within a group of 20 wires in a wire harness will have a
lower maximum current rating than the same wire when it is not in a group. As a good reference, Infineon considers
a reduction of 40% of the nominal current.
Application Note
Smart High-Side Switches
30
Rev 0.3, 2014-10-30
App. Note
Load and Application
Time to destruction (s)
1000
EXAMPLE
ONLY
100
10
1
0
20
40
60
80
Load current (A)
Figure 29
Example of Current Limitation of Wire Harness
5.6
Platform and Vehicle Diversity
100
120
140
wiring.vsd
With the aim of developing better and cheaper new vehicles faster, OEMs have for some years adopted a platform
strategy. This strategy offers the possibility of developing a generic module to address different vehicle platforms,
or different configurations within the same vehicle platform. The diversity of models is huge. A platform approach
offers a great benefit to the OEM. At a module level, the challenge is in the flexibility which can be offered.
Application Note
Smart High-Side Switches
31
Rev 0.3, 2014-10-30
App. Note
Failures in the Field
6
Failures in the Field
Possible failures in the field are usually linked to inter-connection (e.g., short circuit or open circuit load).
6.1
Short Circuit to Ground
The short circuit to GND is extensively described in the AEC Q100-012 documentation for car. There is currently
no AEC-Q100 document in regards to truck devices. This is considered as a good reference by Infineon. Figure 30
shows the hardware configuration of the AEC-Q100-012. The chassis of the vehicle is the GND. The probability
of a short circuit to GND is significant, compared with all other possible short circuit events. This is a challenging
aspect of designing with High Side Switches and will be described later in Chapter 8, which is dedicated to
protection. Without any kind of protection measures, the current will be limited only by the wiring and thus will reach
28V / 30mΩ = 900A. This test is obviously destructive.
AEC short circuit hardware set up .vsd
Figure 30
AEC-Q100-012 Hardware Set-up for Short Circuit Test
The exact short circuit impedance is described in the AEC-Q100-012 document also, an extract of which is shown
in Figure 31.
AEC short circuit impedance .vsd
Figure 31
AEC-Q100-012 Short Circuit Impedance
For truck application, Infineon considers the Figure 31 valid, and modify Figure 30 to reflect the 28V battery
voltage. This set up doesn’t represent the worst case condition for the device. The worst case set-up remains
difficult to define for truck application due to the long harness in use. As an example, the Figure 32 shows the
evolution of the stored inductive energy in a wire harness of 1mm², with a VBAT of 32V and a short circuit current
limited by a device with 65A typical. In such a condition, the worst case short circuit appears to be at 29m.
Application Note
Smart High-Side Switches
32
Rev 0.3, 2014-10-30
App. Note
Failures in the Field
80
70
EA
60
ISHORT
Stored Energy (mJ)
60
50
50
40
40
30
30
20
20
Short Circuit Current (A)
70
10
10
0
0
0
10
20
30
40
50
Wire Lenght (m)
Inductive energy.vsd
Figure 32
AEC-Q100-012 Short Circuit Impedance
6.2
Short Circuit to Battery
There is generally a low probability of a short circuit to the battery, nevertheless it is possible to reach a critical
situation with such a failure. Figure 33 shows a typical case where a short circuit is applied to one of the five
outputs of a given ECU module. When this switch allows the current to flow (in this case, in an inverse mode), the
four other outputs and the module are all supplied by the switch. If the fuse or the relay connection to the supply
battery feed is broken, the complete module supply current will then flow from the output shorted to the battery.
SHORT CIRCUIT
TO BATTERY
VBAT
ECU
Fuse and relay
box
CL15 fuse CL15 switch
GND
GND
Short circuit to battery .vsd
Figure 33
Example of Stressful Short Circuit to Battery Case
Application Note
Smart High-Side Switches
33
Rev 0.3, 2014-10-30
App. Note
Failures in the Field
6.3
Open Load
Open load can be caused by two phenomena, a broken wire or a broken load. Although this is not a critical
scenario, the application usually requires diagnostic information to be sent to the driver. Note that the definition of
an open load is usually OEM dependant. As a good reference, Infineon considers RDIRT = 4.7kΩ resistor to GND.
By law, side indicators have to be reported missing by doubling the flashing frequency. All other open load
diagnosis are OEM requirements only.
6.4
Short Circuit Between Load
A short circuit between loads can occurs anywhere in the wiring path. Consequences can range from a complete
overload, similar to short circuit or a simple additional current with no adverse behavior, except for the unexpected
parasitic switch ON of another load. In Figure 34, the OUT2 switch will be overloaded by the higher load, while
OUT1 will virtually neglect the failure. In generally an OEM will request that this type of failure is diagnosed. Note
that the wiring can also be stressed by such a short circuit event.
VBAT
ECU
OUT1
SHORT CIRCUIT
BETWEEN LOADS
SHORT CIRCUIT
BETWEEN LOADS
OUT2
GND
500mA load
10A load
Short circuit between load .vsd
Figure 34
Short Circuit Between Load
Application Note
Smart High-Side Switches
34
Rev 0.3, 2014-10-30
App. Note
Power Stage
7
Power Stage
The power stage of PROFET™ +24V is a high side switch consisting of a vertical N channel power MOSFET. The
power MOSFET technology is called DMOS. The capability of this power element to pass current can be
expressed in terms of its RDS(ON). The smaller the RDS(ON), the higher the current capability.
7.1
Power Element
The power element for switches is a N channel power MOSFET (DMOS) in the majority of cases. PROFET™ +24V
also use an N channel power DMOS MOSFET as power element. Table 7 summarizes the advantages and
disadvantages of DMOS versus bipolar power structures, assuming the same specifications can be realized with
either technology. It is shown that DMOS offers better performance in short circuit robustness, high voltage
capability and chip size.
Table 7
Comparison between Bipolar and DMOS
Topic
Bipolar
DMOS
+
-
-
+
Accuracy
Offset
Process deviation
Chip area
Voltage capability
High current robustness
Current consumption
Input current
Figure 35 shows the differences between planar and trench (vertical) DMOS technologies. With identical RDS(ON),
it can be seen that the trench DMOS device is smaller. This also results in a smaller gate charge QG for the trench
DMOS device. Since the planar DMOS device is larger, less cooling is required and the EAS is better than the
trench DMOS device. In PROFET™ +24V, the supply is the drain which means that the supply is at the bottom of
the chip. Compared to PROFET+ 12V devices, PROFET™ +24V has an epitaxy thickness increased by 2.5µm.
trench vs planar .vsd
Figure 35
Planar (Left) versus Trench (Right)
Application Note
Smart High-Side Switches
35
Rev 0.3, 2014-10-30
App. Note
Power Stage
The RDS(ON) of PROFET™ +24V can be described as a function of temperature (expressed in °C) See
Equation (6). Figure 36 provides the derating of RDS(ON), assuming 100% at maximum junction temperature.
R DS ( ON ) = R DS ( ON )
–3
150C
(5)
× ( 1 + ( T J – 150 ) × 3, 584 × 10 )
100
Relative RDS(ON)
%
90
80
70
60
50
40
30
20
10
-40
-10
20
50
80
Junction Temperature (Tj)
110
140
RDSON.vsd
Figure 36
Relative RDS(ON), Function of Junction Temperature TJ, base 100 at 150°C
7.2
Voltage Limitation
As with every device based on a given semi-conductor technology, PROFET™ +24V devices have a maximum
voltage. If this voltage is exceeded, the DMOS power stage and/or the logic will avalanche and the device will
quickly be destroyed. Figure 37 shows the influence of temperature on the zenering voltage.
75
74,5
74
73,5
73
DraintoSource
eClampingVDS(AZ) (V)
72,5
72
71,5
71
70,5
70
69,5
69
68 5
68,5
68
67,5
67
66,5
66
65,5
65
40
30
20
10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
JunctionTemperatureTJ (°C)
Figure 37
Min Typical and Maximum Avalanche Voltage, Function of the Temperature TJ
Application Note
Smart High-Side Switches
36
Rev 0.3, 2014-10-30
App. Note
Power Stage
7.3
Charge Pump
When the DMOS is ON, the output voltage is very close to the supply voltage VS. As the power stage is an N
channel power DMOS, the device requires a charge pump to provide a VGS ~ 7V. The concept of a charge pump
is described in Figure 38. In the first phase, the CLOAD capacitor is charged up to the VS voltage. In phase two, the
CLOAD is discharged through a diode into CCP, the charge pump capacitor. The charge pump runs at a frequency
of 2.5MHz. The voltage rises in steps of CLOAD / CCP, to theoretically twice the battery voltage. In practice, this
voltage is limited to 10V above VS. The ratio is CCP = CLOAD.
VS
VS
- VS +
- VS +
VS
S1
S1
S3
S3
TO GATE DRIVER
CLOAD
CLOAD
CLOAD
+
S2
CCP
+
CCP
VCP
-
VCP = VS
S2
+
CCP
VCP = VS (1+ CLOAD/CCP)
-
-
GND
PHASE 1
PHASE 2
Charge pump principle.svg
Figure 38
Charge Pump Block Diagram
7.4
Slope Control Mechanism
For EMC reasons, PROFET™ +24V devices have embedded slope control for both switch ON and switch OFF.
The actual switching event is divided into three stages. Refer to Figure 39. First, the gate of MOSFET is connected
to VS via current generator. tON_delay is linked to the necessary time for the gate to reach ~2V. Then the MOSFET
switches ON quickly. A fast switch ON time is required to minimize switching power losses (refer to Chapter 7.5).
As soon as VOUT reaches ~70% of the supply voltage VS, the charge pump starts to drive the gate to obtain the
minimum RDS(ON) of the device. The slope is reduced due to the necessary time to completely load the gate
capacitance. Compared to PROFET + 12V, the PROFET™ +24V switch ON and OFF faster. Two reasons explain
this. First, the slope control of PROFET + is battery dependant such as PROFET + switches double faster if the
battery is twiced. From 13.5V to 27V, the PROFET + switches from 0.25 V/µs to 0.5V/µs. Additionally, the gate
driver has been improved to increase even more the speed. The target is to be more compliant to inductive loads
driven in fast PWM and to improve the switches losses.
Application Note
Smart High-Side Switches
37
Rev 0.3, 2014-10-30
App. Note
Power Stage
IN
t
VOUT
90% VS
tON
t OFF_delay
70% VS
dV/dt
30% VS
ON
dV/dt
tON_delay
OFF
tOFF
10% VS
t
Switching times .vsd
Figure 39
Switch ON and Switch OFF timing
At switch OFF, a similar behavior is observed. First, the charge pump is disconnected and a strong current
generator IFASTGATEUNLOAD quickly discharges the gate charged of electrons until VOUT reaches ~70%. Then the
gate is discharged with a constant current IGATEUNLOAD until the gate voltage is zero. Figure 40 shows the block
diagram of the gate driver.
VS
VCP
I GATELOAD
To gate
of the power
MOSFET
IFASTGATEUNLOAD
IGATEUNLOAD
OUT
Gate driver .vsd
Figure 40
Gate Driver Schematic
The EMC performance when driving the HSS with a PWM waveform has been improved thanks to the additional
current matching measures. PROFET™ +24V offers matching of the loaded current IGATELOAD and the unloaded
current IGATEUNLOAD. This matching can be found in all PROFET™ +24V datasheets under the Slew rate matching
parameter ΔdV/dt.
7.5
Power Losses Calculation
The power losses P in the device, assuming a resistive load RL, can be calculated as follow. (Refer to Figure 41).
The instantaneous power in the switch is the result of the load current IL multiplied by the drain to source voltage
VDS = VS - VOUT. The resulting curve is shown in Figure 41. A good approximation is realized by the orange
isosceles triangles and the rectangle.
Application Note
Smart High-Side Switches
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Rev 0.3, 2014-10-30
App. Note
Power Stage
The triangle has as vertex at PMATCH which is the physical point where the switch resistance corresponds to the
exact load resistance i.e. RDS(ON) = RL. Equation (6) gives the relationship between PMATCH and RL.
2
P MATCH
VS IL
VS
= ------- × ---- = ---------------2
2
4 × RL
(6)
As the drivers are very symmetrical, it is assumed switching ON tSON and switching OFF tSOFF times are identical
i.e. tSON = tSOFF. The area of the triangle represents the switching energy and is defined by Equation (7).
1
E SON = E SOFF = --- × P MATCH × ( t ON – t ONdelay )
2
(7)
The orange rectangle represents the energy ER(ON) lost during the ON state of the DMOS power element and is
easily calculated by Equation (8).
E RON = R DSON × I
2
L
× t RON
(8)
In conclusion, the power losses in the DMOS power element calculated by using Equation (9).
( 2 × E SON + E RON )
P = ----------------------------------------------t CYCLE
Application Note
Smart High-Side Switches
(9)
39
Rev 0.3, 2014-10-30
App. Note
Power Stage
t cycle
IN
VOUT
90% VS
tON
tOFF_delay
70% VS
dV/dt ON
dV/dt OFF
50% VS
30% VS
tON_delay
tOFF
10% VS
t
IOUT
90% IL
70% IL
50% IL
30% IL
10% IL
t
PLOSS
P MATCH
RDS(ON)* IL
t
tON
tSON
tSOFF
Switching Losses.svg
Figure 41
Power Losses Calculation
7.6
Switch Behavior with PWM Input
Pulsed Width Modulation is a special case where the cycle time, tCYCLE is the inverse of the PWM frequency fPWM.
There are four limitations of PROFET™ +24V which need to be considered when using a PWM waveform. These
are power loss, EMC emissions, switching time and diagnostic limitations. Power loss and switching time issues
will be described below. The EMC and diagnostic limitations will be described in dedicated chapters (Chapter 9.8
and ).
Figure 42
7.6.1
PROFET™ +24V PWM Limitations due to Power Losses
The capability to drive a load with a PWM waveform is often limited by the maximum power loss allowed in an
application. This is critical for fast fPWM frequency or when the load has a relative low resistance. (Refer to
Chapter 7.5 for details how to calculate the power losses). To calculate the maximum power losses an application
can support, refer to Chapter 7.7. Where the power losses are unacceptable for the device, the easiest solution
is to either reduce fPWM, or to use a device with lower RDS(ON).
Application Note
Smart High-Side Switches
40
Rev 0.3, 2014-10-30
App. Note
Power Stage
Figure 43 shows the power loss in a BTT6050-2EKA when driving a 2 x 21W bulb. The PWM regulation voltage
of 24V with PWM frequencies of zero, 100Hz and 200Hz is shown. The switching time is assumed to be tSON =
tSOFF = 65µs.
0,4
power losses with 200 Hz PWM
power losses with 100 Hz PWM
Power Losses (W)
0,35
power losses with no PWM (W)
0,3
0,25
0,2
0,15
0,1
18
24
30
36
Supply Voltage (V) VS
Figure 43
BTT6050-2EKA Power Losses in PWM with a 2 x 21W truck Bulb Load. VPWM = 24V
7.6.2
PROFET™ +24V usage in 12V system
Although PROFET™ +24V are designed to be used in 24V system, it can be requested to use the device in 12V
application. In such a case, the wattage should be decreased to half the wattage used in 24V system such as a
2x21W_truck capable switch in 24V becomes a single 21W car. Figure 44 shows the power loss in a BTT60502EKA when driving a 2 x 21W_car bulb. The PWM regulation voltage of 13V with PWM frequencies of zero, 100Hz
and 200Hz is shown. The switching time is assumed to be tSON = tSOFF = 65µs.
Application Note
Smart High-Side Switches
41
Rev 0.3, 2014-10-30
App. Note
Power Stage
2
Power Losses (W)
1,8
1,6
1,4
1,2
power losses with 200 Hz PWM
power losses with 100 Hz PWM
1
power losses with no PWM (W)
0,8
8
9
10
11
12
13
14
Supply Voltage (V) VS
15
16
17
18
Power losses in PWM _truck_car.vsd
Figure 44
BTT6050-2EKA Power Losses in PWM with a 2 x 21W car Bulb Load. VPWM = 13V
7.6.3
PROFET™ +24V PWM Limitations Due to Switching Time
To determine the minimum turn ON time, it is necessary to define when the DMOS power switch is actually ON.
This is assumed to be when the output reaches a minimum of 90% of VS. As described in Chapter 7.4, PROFET™
+24V have a defined switching sequence. The minimum turn on time, tRON represents the minimum time the switch
ON. Refer to Figure 45. The specified turn ON time to 90% of VS, tON defines the fastest input pulse which will turn
the switch ON. With an input pulse of this length, tRON is smaller than the turn off delay, tOFF_delay which is the
smallest ON time a PROFET™ +24V reaches. A similar example can be used to show the minimum OFF time
possible which is limited by tON_delay assuming the switch is OFF if the output voltage is below 10% of VS.
tRON
TPWM
IN
VOUT
tOFF _delay
90% VS
70% VS
50% VS
30% VS
tON _delay
10% VS
t
tON
t OFF
minimum tON.vsd
Figure 45
Minimum tRON
Application Note
Smart High-Side Switches
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Rev 0.3, 2014-10-30
App. Note
Power Stage
tOFF_delay * fPWM is the smallest duty cycle, dMIN the device can handle. At this point, it is useful to compare
the PWM input parameters with the corresponding PWM output parameters. To perform this
comparison the accuracy, minimum and maximum duty cycle and maximum fPWM of the PROFET™ +24V
must be known. An example of this comparison is shown in Table 8. Improved accuracy and resolution
has been realized with better device symmetry (see Chapter 7.4). This can be measured by the
introduction of ΔtSW , the turn-ON/OFF matching parameter.
Table 8
PROFET™ +24V PWM Timing Limitation
Parameter
fPWM =
fPWM =
fPWM =
fPWM =
100Hz
200Hz
400Hz
1kHz
1/fPWM
10
5
2.5
1
ms
tOFF_delay/TPWM
tON/TPWM
tON_delay/TPWM
tOFF/TPWM
Δ tSW / 2TPWM
0.7
1.4
2.8
7
%
1.5
3
6
13
%
99.3
98.6
97.2
93
%
98.5
97
94
85
%
0.25
0.5
1
2.5
%
Symbol Formula
Period
min duty cycle at the output
min duty cycle at the input
max duty cycle at the output
max duty cycle at the input
Accuracy
TPWM
dOUT_MIN
dIN_MIN
dOUT_MAX
dIN_MAX
aPWM
Unit
It is important to note that the resolution is mainly determined by the software and the microcontroller. PROFET™
+24V will have an influence on the accuracy of the resolution only.
7.7
Thermal Considerations
PROFET™ +24V devices are embedded in exposed pad packages. Exposed pad packages offer excellent
thermal resistance (ZTH(JA) characteristics) between the junction and the case compared with non-exposed pad
packages. PROFET™ +24V devices in exposed pad packages also have better immunity to variations in the
power supply and power surges. Limitations to the system are based on two different thermal aspects:
7.7.1
Maximum Junction Temperature
PROFET™ +24V should be kept below TJ(SC) = 150°C. Equation (10) expresses this constraint mathematically.
T J ( SC ) – T MODULE
P MAXTJ = --------------------------------------------R THJA
(10)
A minimum of 1W (high ambiente temperature and/or bad cooling) and a maximum 2W are seen. Typically a
maximum of 1.4W gives good results.
7.7.2
Maximum Case Temperature
PROFET™ +24V case temperature should be kept below the destruction temperature of the PCB. This is
application dependent. As a good reference, Infineon uses max TC = 130°C for standard FR4. Equation (11)
expresses this constraint mathematically.
T CMAX – T MODULE
P MAXTC = -----------------------------------------------R THJA – R THJC
7.7.3
(11)
Maximum Power in PROFET™ +24V
The maximum power a PROFET™ +24V can handle in an application is limited by the lesser of these two
quantities, PMAXTJ and PMAXTC. Table 9 provides some examples of how PMAXTJ or PMAXTC limit the maximum power
Application Note
Smart High-Side Switches
43
Rev 0.3, 2014-10-30
App. Note
Power Stage
of the device for different values of ambient temperature and different thermal resistances. A maximum PCB
temperature of 130°C is assumed.
Table 9
Comparison between Exposed and Non Exposed Package with PCB Limitation = 130°C
Ambient Temp
Package
RTHJC RTHJA Max power due to Maximum power due to Maximum power
PCB temperature1) junction temperature2)
85
105
1)
2)
Exposed
1
30
1.6
2.2
1.6
Exposed
1
40
1.2
1.6
1.2
Exposed
1
50
0.9
1.3
0.9
Standard
15
50
1.3
1.3
1.3
Standard
15
60
1.0
1.1
1.0
Standard
15
70
0.8
0.9
0.8
Exposed
1
30
0.9
1.5
0.9
Exposed
1
40
0.6
1.1
0.6
Exposed
1
50
0.5
0.9
0.5
Standard
15
50
0.7
0.9
0.7
Standard
15
60
0.6
0.8
0.6
Standard
15
70
0.5
0.6
0.5
TC <130°C
TJ < 150°C
7.8
Inverse Current
There are four main reasons for inverse currents in an application. The reasons are: driving of a capacitive load;
output wired to the battery (on purpose or by accident), driving an inductive load, and severe alternator ripple.
7.8.1
Capacitive Load
Figure 46 shows a typical case where inverse current can be observed.
ECU
+ VBAT_DROP -
- VDIODE +
I BAT
+
+
+
IINV
CL
VBAT
VS
IBAT _ECU
-
-
VOUT
-
capacitive load illustration .vsd
Figure 46
Capacitve Load and Inverse Current Illustration
Application Note
Smart High-Side Switches
44
Rev 0.3, 2014-10-30
App. Note
Power Stage
CL is charged up to voltage VOUT. An inrush current IBAT_ECU applied inside the module induces a voltage
drop VBAT_DROP in the module's supply wiring. The consequence of this is that VS, the voltage supply of
the module can drop below VOUT. During a severe IBAT_ECU inrush event, the difference between VOUT
and VS can be sufficient to activate the internal parasitic diode (VBAT_DROP > Vdiode e.g. 300mV) or use
the RDS(ON) of the power DMOS to cause IINV current to flow.
7.8.2
Output wired to Battery
A short circuit to battery is very similar to the capacitive load except that a permanent inverse current can be
assumed. With a short circuit to the battery, VOUT is VBAT. VBAT_DROP can be more than 300mV permanently which
can create extra stress on the switch. Refer to Chapter 6.2.
7.8.3
Inductive Load
With an inductive load, such as an H bridge motor, the current can freewheel in either the low side or the high side
of the bridge again causing and inverse current to flow in the switch.
7.8.4
Alternator Ripple
Ripple caused by the alternator is common and is most noticeable when the alternator has a large load current.
As a good reference, Infineon uses a ripple of 3V peak to peak at the module supply VS, with a frequency of
minimum 1kHz, maximum 20kHz. During the negative slope of the ripple, the capacitor, CL can be sufficient to
provide current to the load. In this situation, the switch is ON and the current is slowly decreasing until crossing 0
and continuing in a negative direction, limited by the RDS(ON) or the body diode of the switch. Figure 47 shows this
situation, assuming a 3A resistive load decoupled with a 50µF capacitor and a ripple frequency of 1kHz ripple. This
example is based on the BTS5045-2EKA.
V B AT
I LOAD
17,0
3,5
16,5
2,5
16,0
Voltage (V)
15,0
0,5
14,5
-0,5
14,0
Current (A)
1,5
15,5
Alternator ripple
13,5
-1,5
Output voltage
13,0
Output current
-2,5
12,5
12,0
-3,5
0
250
500
750
1000
1250
1500
1750
Tim e (µs)
alternator ripple .vsd
Figure 47
Alternator Ripple. Voltage and Current of PROFET™ +24V with Capacitor as Load
7.8.5
Consequences for PROFET™ +24V
During inverse current, due to internal parasitic behavior, two kinds of phenomenon can be observed. With a large
inverse current IINV, well above the nominal current of the device, IL(NOM), a parasitic switch ON or OFF of a
neighboring channel can be seen (in devices with two or more channels of course). The second effect, described
in Figure 48 is where the DMOS power switch will not turn ON if the input on the IN pin is changed to high while
the inverse current is flowing (see case 3). In all other cases, the MOSFET switches according to the IN pin logic
level. The inverse current also impacts the diagnosis behavior. Refer to Chapter 9. The parameter IL(INV) in
Application Note
Smart High-Side Switches
45
Rev 0.3, 2014-10-30
App. Note
Power Stage
datasheet represents the current below which no parasitic behavior of a neighboring channel or parasitic diagnosis
is observed.
IN
IN
CASE 1 : Switch is ON
CASE 2 : Switch is OFF
OFF
ON
t
NORMAL
t
IL
IL
NORMAL
NORMAL
t
NORMAL
t
INVERSE
INVERSE
DMOS state
DMOS state
OFF
ON
t
t
CASE 3 : Switch ON into inverse
CASE 4 : Switch OFF into inverse
IN
IN
OFF
t
t
IL
IL
NORMAL
NORMAL
NORMAL
t
NORMAL
t
INVERSE
INVERSE
DMOS state
DMOS state
OFF
OFF
ON
ON
ON
ON
OFF
t
t
Power stage Inverse conditions .vsd
Figure 48
Behavior of PROFET™ +24V in Inverse Current
Application Note
Smart High-Side Switches
46
Rev 0.3, 2014-10-30
App. Note
Protection
8
Protection
A comprehensive set of protection functions are one of the most important features offered by PROFET™ +24V
switches.
8.1
Band gap
PROFET™ +24V have an embedded band gap reference. Although the band gap reference is not a protection
circuit in itself, most of the protection circuits rely on this reference voltage. The band gap voltage is VBG = 1.25V.
The accuracy is 4% over temperature and supply voltage.
8.2
Short Circuit to Ground
As mentioned previously (refer to Chapter 6.1), a short circuit to GND is the most likely short circuit event in a
vehicle. As a result, PROFET™ +24V devices embed several mechanisms to protect against short circuits to
ground.
8.2.1
PROFET™ +24V Current Limitation
As with all types of power MOSFET technology, the DMOS switch in PROFET™ +24V should not exceed a certain
power or current density. The power density reflects the power in the DMOS switch per unit of surface area. Since
the power PMOS = VDS * IMOS, and PMOS is limited to a constant, the IMOSMAX the DMOS can handle is then given
by Equation (12).
P MOS Cons tan te
I MOSMAX = ------------- = -------------------------V DS
V DS
(12)
Interestingly, with such an equation, a 0V drop voltage will lead to an infinite current. Obviously, this is theoretical
only, and the real current limitation, for low voltage drop, is related to wire bonding. The bonding cannot support
more current than a certain fixed value. The constraints, linked to the technology looks as the given curve
Figure 49. The blue curve matches the MOSFET power density only. The red curve sketches the overall device
limit. The protection concept should guarantee to limit the current below the device system limitation.
140
120
Destructive current (%)
100
80
60
40
20
0
0
5
10
15
20
25
Drain source Voltage VDS (V)
Figure 49
30
35
40
Current limit concept _truck. vsd
Power DMOS and Package SOA
Application Note
Smart High-Side Switches
47
Rev 0.3, 2014-10-30
App. Note
Protection
8.2.2
PROFET™ +24V Current Limitation Concept
PROFET™ +24V devices limit the current flowing through the DMOS switch. The reason for limiting instead of
tripping, is due to the fact that PROFET™ +24V devices are designed to drive lamps. As described in
Chapter 5.1.3, lamps have a significant inrush current at turn ON. To ensure a lamp is turned ON in the worst case
scenario, it is necessary to allow this inrush current to flow for a short period of time. The current limitation looks
as described on Figure 50, the blue colors reflecting the tolerance.
100
90
80
Destructive current (%)
70
60
50
40
30
20
10
0
0
10
20
Drain source Voltage VDS (V)
Figure 50
30
40
Device Current limit truck .vsd
Current Limitation
As described in Table 4, each lamp has an inrush. Figure 51 shows the consequence for the PROFET™ +24V
when turning on a lamp. The orange line represents the inrush current of the bulb. The device will be considered
suitable for a lamp when the IINRUSH will not touch the low current limitation (risk of accelerated aging) hence it may
touch the high limit one when VDS is smaller 3V. In that case, an over temperature condition having for
consequence latching of the device might be observed. The software should perform a single restart to ensure the
lamp to turn ON as most of the inrush energy is already transfered.
Application Note
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48
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App. Note
Protection
50
Inrush current and Current Limit (A)
40
30
20
10
0
0
10
20
30
Drain source Voltage VDS (V)
40
lamp Current limit truck.vsd
Figure 51
Turning ON 2*21W with BTT6050-2EKA. Inrush versus Current Limitation
8.2.3
Temperature Swing Limitation
Severe temperature gradients on chip cause significant thermo mechanical stress and aging of the device to the
point of destruction. The smaller the temperature gradient, the higher the number of cycles the PROFET™ +24V
can withstand. A temperature swing of 60Kelvin minimum is a good compromise value to use for lamp turn ON
and to protect against severe short circuits. Figure 52 shows the hardware realization of the 2 x 50 mΩ BTT60502EKA. Two temperature sensors, one measuring the DMOS, one measuring the chip temperature are compared.
The channel turns OFF when a too high temperature gradient is reached. To guarantee the functionality accuratly,
variation due to temperature and production spread is greatly reduced thanks to the use of the internal band gap
reference.
DMOS
Channel 0
DMOS
Channel 1
TEMPERATURE
DIFFERENCE
Logic of the Channels
temperature swing concept .vsd
Figure 52
Temperature Swing Limitation Concept
Application Note
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App. Note
Protection
8.2.4
Maximum Temperature Limitation
The device (chip + package) is qualified for junction temperature up to TJ = 150°C continuous. Above, the over
temperature sensor of the chip is met. This sensor is typically activated at a temperature of TJ = 175°C. The
hardware designer should guarantee with its thermal design the device to operate below TJ = 150°C by verifying
Equation (10).
8.2.5
Restart Strategy
During the switch ON phase of a bulb load higher than the nominal one, the temperature rise in the device can be
higher than 60K. To ensure that the bulb is turned ON, (refer to Chapter 5.1.3), even under these conditions, a
restart strategy could be implemented. As the device is a latch device, a software restart should take place. The
IN pin should toggle LOW to HIGH. If the device is still in the cool down phase no restart is possible and the rising
edge of the INPUT is ignored. Refer to Figure 53
Reset too early
INPUT
t
T DMOS
T J(SC)
DMOS temperature
T SWING
T SWING HYS
t
t HEATING t COOLING
Reset sucessful
INPUT
t
T DMOS
T J(SC)
DMOS temperature
T SWING
T SWING HYS
t
t HEATING t COOLING
Figure 53
DMOS Temperature Behavior during Restart Phase
8.2.6
PROFET™ +24V Life Time Limitation
temperature swing timing truck.vsd
Although significant design effort has been put into protecting against a short circuit to GND, PROFET™ +24V
devices are not indestructible. To protect the device, it is necessary to limit the number of restarts to a minimum.
Refer to Figure 54. Usually, 2 retries are enough to discriminate between high inrush and real short circuit
condition. As the device is a latch device, all measured short circuit event during device validation should be
Application Note
Smart High-Side Switches
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Rev 0.3, 2014-10-30
App. Note
Protection
considered as a short circuit event. In the Figure 54 example, two short circuits should be incremented to the short
circuit counter.
Driver
command
t
IN
t RESTART
t
IL
I L(SC))
1
2
t
restart event limitation t ruck.vsd
Figure 54
Number of Restart Limitation
8.2.7
Activation Limitation
Figure 55 provides a picture of a BTS5241L which has been exposed to repetitive short circuit stress. The channel
on the right hand side has not experienced any events while the other channel has experienced thousands of
repetitions. This provides a visual confirmation of the aging effect due to repetitive short circuit events.
Figure 55
Device Exposed to Short Circuit Stress
As soon as a short circuit is detected, a plausibility check should be performed. This is achieved by changing the
IN pin status from LOW to HIGH again to ensure the diagnosis is correct. If a certain number of short circuit events
are detected, the system should then inhibit the function controlled by the switch until the next ignition cycle of the
vehicle starts.
To implement this strategy, a counter CDRIVE has to be created. CDRIVE is used to count the number of short circuit
events each PROFET™ +24V output has encountered in an ignition cycle (a short circuit cycle corresponds to an
event where after TRESTART, the device is still in short circuit). When CDRIVE reaches a predefined value, the load is
inhibited (i.e. no further activation).
Application Note
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Protection
Another counter, CLIFE is then incremented. CLIFE should be stored in a non volatile memory such as Flash or
E²Prom. Infineon provides the quantity CDRIVE * CLIFE in datasheet based on the short circuit robustness test. In
Chapter 5.4 a rough clustering of loads or load families based on the number of activations per ignition cycle was
given. Although the final decision always rests with the OEM, Table 10 provides suggested values for CDRIVE for
a given load family.
Table 10
Load Family, Function of Engine Ignition
N° of driver
activation
Load example
Average activation Plausibility check
time
realized by
CDRIVE
Inhibition after
High
Brake light
< 1mn
Vehicle driver
3 to 5
High
Low beam
> 1mn
Vehicle river
3 to 5
Mid
Interiors
> 1mn
Application
5
Mid
Low beam
> 1mn
Application
5 to 10
Low
High beam
> 1mn
Application
5 to 10
Using Table 10, a software strategy can be implemented based on the number of activations per ignition cycle,
the average driver usage as well as the length of time of activation. A load which is known to be used often will
not need an automated retry. A load which is activated once in a while but for long periods of time will need an
automated retry. Figure 56 shows these two possibilities. TWAIT is usually selected by the OEM. (in the range of
1s to 2mn). Figure 57 shows a suggested software flow chart.
Driver request
t
IN
IGNITION
CYCLE
IGNITION CYCLE
t
CDRIVE = 1
CDRIVE = 2
CDRIVE = 0
CDRIVE = 3
CLIFE = CLIFE +1
Driver request
t
IN
IGNITION
CYCLE
IGNITION CYCLE
TWAIT
CDRIVE = 1
t
TWAIT
CDRIVE = 2
CDRIVE = 0
CDRIVE = 3
CLIFE = CLIFE +1
Figure 56
software timing strategy
truck.vsd
Software Strategy
Application Note
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Protection
New vehicle
CLIFE = 0
System OFF
Ignition ON
System ON
CDRIVE=0
Device OFF
Activation = driver wish
Device ON
Ignition ON
IGNITION
CYCLE
No
Diagnostic read out
SC ?
System OFF
Yes
Definitive device
inhibition
No
Yes
CLIFE > CLIFE max
Activation =
Driver wish
or
Retry strategy
Device OFF
CDRIVE=CDRIVE+1
CDRIVE > CDRIVE max
Yes
No
Device OFF
Device inhibition
CLIFE=CLIFE+1
System OFF
Software strategy.svg
Ignition OFF
Figure 57
Short Circuit Software Strategy
8.2.8
Short Circuit to GND with Long Wire Harness
A specific requirement of the truck application in regards to car is the wide spread of harness diversity, from short
to very long wires. Refer to Figure 58. The inductive energy stored in the harness during short circuit cannot be
neglected.
ECU
5m
5
m
40m
ECU
car and truck wire.vsd
Figure 58
Truck Architecture and Long Wire Harness
Application Note
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53
Rev 0.3, 2014-10-30
App. Note
Protection
The short circuit definition, as the AEC-Q100 defined it, is obsolete, or at least subject to discussion. Figure 59
represents a typical case with the BTT6050-2EKA, 46A typical current limitation. The harness increases with
16mΩ/m and 1µH/m, representing a typical 1mm² cable diameter impedance. The battery voltage is 28V. In such
a case, the stored energy is maximum, and therefore the short circuit stress is maximum around 36m. In case of
a longer harness, the device is not actively limiting the current.
50
50
EA
45
ISHORT
40
40
35
35
30
30
25
25
20
20
15
15
10
10
5
Shorrt Circuit Current (A)
Stoored Energy (mJ)
45
5
0
0
0
10
20
30
40
50
Wire Lenght (m)
Figure 59
Long Wire Harness and Stored Inductive Energy during Short Circuit Event
8.3
Short Circuit to Battery
A short circuit to the battery can be a very stressful event for a PROFET™ +24V device. Refer to Chapter 6.2 and
Chapter 7.8. Several workarounds can be implemented with the best solution being to place a diode in series with
the output. While this solution is good in theory, the cost is often prohibitive. An alternative strategy is to guarantee
that no excessive current will flow in the device. To implement this, the system must perform a short circuit to
battery test. If a short circuit to the battery is indicated, the battery supply line of the PROFET™ +24V must not be
switched OFF. If the battery's supply line is not available (for example due to a blown fuse), the alternative is to
use a POWER PROFET TM which will perform intelligent restart. At last, turn-OFF every device connected to the
faulty supply line in order to reduce the inverse current in the body diode. The three solutions are summarized in
Figure 60.
Application Note
Smart High-Side Switches
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App. Note
Protection
SHORT CIRCUIT
TO BATTERY
ECU
VBAT
Diode
solution
Fuse and relay
box
CL15 fuse CL15 switch
Switch kept ON with
Power profet
GND
Inhibition
of the
loads
GND
Short circuit to battery.svg
Figure 60
Short Circuit to Battery Protection Possibilities
8.4
Open Load
Open Load is not considered as a destructive case for the device.
8.5
Loss of battery
The loss of the battery while the switch is ON has no influence on device’s robustness when load and wire harness
are purely resistive. In the case of inductivity, the energy stored in the inductance brings additional issues which
should be handled with care. Figure 61 shows the system set up in that case.
Application Note
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Rev 0.3, 2014-10-30
App. Note
Protection
-
VRI +
R1/L1
-xV
+
VIS(AZ)
-
IS
VS
-xV-0.7V
IBAT
ZIS(AZ)
+
-
IN
-xV+6V
-
VDS(AZ)
VZ(AZ)
-
ZD(AZ)
ZDS(AZ)
+
VBAT
-
+
RIS
VIS
+
VIN
IL
ZDESD
OUT
-xV - 0.7V - 70V
RIN
-
+
GND
-xV
VLOAD
R2/L2
+
VGND
ZGND
+
0V
Figure 61
Loss of battery protection - truck.vsd
Loss of inductive load
Due to the inductivity, the current looks for the easiest (lowest ohmic) path to flow. This path consists of the
freewheeling of the GND circuitry and of the over voltage ZD(AZ) diode. For that reason, it is necessary to let the
current flow in the opposite direction in the GND circuitry, otherwise thousands of Volt will be seen at the pins. The
power DMOS is big enough to handle the energy, the ZD(AZ) diode is less robust. An equivalent robustness would
mean a GND DMOS as big as the power DMOS which is financially not sustainable. PROFET™ +24V devices
handles inductivity of the wire harness, up to 10µH with the nominal current of the given device. In the case of
applications where currents and / or the inductivity should be exceeded, an external freewheeling diode, in parallel
to the device or in parallel to the load is necessary to handle the energy.
8.6
Short Circuit Between Loads
Short circuit between loads is usually detrimental to the application affecting PCB traces, connectors and wiring.
For PROFET™ +24V, the consequences depend mainly on which additional load is added by the short circuit.
As extreme example, a 70W lamp which is short circuited to a 5W lamp will bring no difference to a 70W
PROFET™ +24V driver while a 5W PROFET™ +24V driver will effectively be short circuited to ground.
Thanks to the embedded temperature swing limiter, the PROFET™ +24V will be able to turn the over-load inrush
ON. If the ambient temperature is below the maximum ambient temperature the system is designed for, the
PROFET™ +24V will either go into thermal shutdown very late or not at all. Nevertheless, it's life expectancy will
be reduced by the over current events.
To define the maximum current acceptable for a device the ZTH(JA) information must be known. Any current which
is applied for a period of time and leads to a temperature swing of more than 60K is considered to be outside the
nominal range. This current will accelerate the ageing of the PROFET™ +24V. As an example, Figure 62 shows
the maximum current that can be handled by each PROFET™ +24V.
Application Note
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Rev 0.3, 2014-10-30
App. Note
Protection
Max Current (A)
100
10
1
0,1
1
10
100
1000
Time (ms)
Figure 62
Typical Couple Current / Time to 60K Temperature Swing
8.7
Undervoltage
A low supply voltage condition brings two challenges which must be addressed, protection and switching
capability. Refer to Figure 63.
8.7.1
Protection
Thanks to the internal band gap (BG) reference, PROFET™ +24V devices are protected in under-voltage
conditions. A valid band gap allows the device to turn ON. In this case, all protection mechanisms are functional.
An invalid band gap, due to insufficient supply voltage causes the PROFET™ +24V to turn OFF. When the BG is
valid, the charge pump (CP) voltage is not necessarily valid, however, the charge pump is monitored and BG will
prevent switch from turning ON when the CP voltage is invalid.
8.7.2
Switching Capability
The capability of a PROFET™ +24V to turn ON and to reach the correct RDS(ON) area is based on the charge
pump's capability to drive the gate of the power DMOS transistor (refer to Chapter 7.3). This is defined in the data
sheet by the supply voltage VS being the range VNOM. When the supply voltage VS is below this range, the situation
prior to reaching the under-voltage zone is of primary importance. If Vs is decreasing, the device is kept ON down
to a threshold in the range of VS(UV). This is assuming the IN pin is kept to a HIGH level. If Vs is increasing, the
device will switch ON when VS reaches the threshold VS(OP)_EXT. Figure 63 shows the behavior in the three areas
of supply voltage with respect to time.
Application Note
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57
Rev 0.3, 2014-10-30
App. Note
Protection
IN
VS / VOUT
R D S(ON ) *IL
V S(OP) min = 8V
VS(OP) ext = 4.5V
VS(U V) min = 2V
Turn ON delay
1.5V max
t
undervoltage behavior .vsd
Figure 63
Behavior during Undervoltage Reset and Ramp up test
8.7.3
Ignition
During ignition, and depending on the OEM minimum voltage VCRK_MIN, a switch which was previously ON can turn
OFF. Refer to Figure 64. When the VS voltage rises again, the switch will automatically restart and turn ON if the
IN pin is kept in the high state. During tLAUNCH, VS can be below VS(OP)min. As a consequence, the RDS(ON) can be
higher than specified. To avoid an intermediate state, every PROFET™ +24V is tested to provide a voltage drop
of less than 1.5V.
IN
t
V
VBAT_R UN
VBAT _STD
VCRK_OSC
VCRK_LAU NCH
VCRK_MIN
t
t
LAUNCH
CRK
t
Cranking pulse .vsd
Figure 64
Ignition Pulse and PROFET™ +24V Behavior
8.7.4
Low Battery Voltage Phase
During a low battery condition, a parasitic under-voltage turn OFF could occur, especially if a capacitive load with
IINRUSH peak current has to turn ON or if there is a short circuit to GND. Since the wiring is inductive, IINRUSH will
produce a VDROP voltage. Refer to Figure 65. VDROP can be estimated by Equation (13).
Application Note
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Protection
R and L are the respective resistance and inductance of the supply line. Δt corresponds to the PROFET™ +24V
switching time. IINRUSH is the worst case peak current of the short circuit current or current limitation. As a good
reference, Infineon consider L = 10µH, R = 20mΩ. Refer to Table 11 for expectable voltage drop during IINRUSH.
I INRUSH
V DROP = L × -------------------- + R × I INRUSH
Δt
(13)
Relay and
Fuse box
ECU
Vdrop
+
+
I INRUSH
CLx
VSx
+
Battery V
BAT
VS
GND
-
GND
undervoltage hardware set up .vsd
Figure 65
Low Battery Voltage Condition. Inrush and Inductive Wiring Influence
Table 11
Load and Maximum Instantaneous Expectable Voltage Drop
Load (W)
Inrush (A)
Maximum Voltage Drop (V)
5
5
0.35
10
9
0.65
21
22
1.5
2*21
57
4
3*21
85
6
70
50
3.5
8.8
Overvoltage
Overvoltage is considered to be everything above VBAT(SC). As described in Chapter 4.1.5, the main causes of over
voltage are external jump start and load dump.
8.8.1
Jump Start
Jump start is usually not a stressful situation. The only situation in which PROFET™ +24V devices cannot cope
during a jump start is during a simultaneous short circuit to GND at the output. This is considered a double fault,
and it is not usually required to survive such a coincidence. In this case, the device will survive a single short circuit
event. Turning OFF the load is recommended when the voltage increases above VBAT(SC). If the load is a lamp,
this procedure is even recommended to maintain the life time of the bulb.
8.8.2
Load Dump
Load dump is an extreme application scenario for a PROFET™ +24V and can be destructive test due to thermal
over-stress. Refer to Figure 66. As soon as the VS potential is higher than VS(AZ), VIS(AZ) or VDS(AZ), the respective
Zener diode conducts. The temperature and current coefficients are positive which means that all the Zener diodes
Application Note
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59
Rev 0.3, 2014-10-30
App. Note
Protection
are conducting almost at the same time. The load dump is specified with RI (internal load dump generator resistor)
which will limit the current. Note that this resistor is OEM dependant. The ISOV current flows via the sense
protection Zener ZIS(AZ), the logic protection Zener ZD(AZ), and the power stage Zener ZDS(AZ).
To define the robustness of the system against load dump, the currents and voltages of Figure 66 must be solved
(Millman theorem helps). When this is complete, a power calculation can be done to determine if the system is
capable of handling the total energy. Resistors RIS, RIN and RGND are used to limit the current (ISOV_SENSE, IDESD,
ISOVLOGIC respectively). It is important to note that in a load dump situation, the load is activated and some current
ISOV_LOAD flows. The choice of RGND is explained in Chapter 10.1.
~68V
-
VRI +
Ri
~3V
- VIS(AZ) +
IS
ZIS(AZ)
ISOV_SENSE
+
+
ID_ESD
~2V
VZ(AZ)
IN
+
RIS
+
VESD
-
VIN
RIN
ZDS(AZ)
70V
VDS(AZ)
+
-
VLD
ZD(AZ)
ISOV_LOAD
-
VIS
ISOV
VS
ZDESD
ISOV_LOGIC
OUT
-
~3V
+
-
GND
~3V
+
IGND
VLOAD
+
VGND
R;L;C
RGND
Overvoltage protection
truck.vsd
Figure 66
Over Voltage Protection. Example with 70V
8.9
Reverse Polarity
In reverse polarity situations where loads have symmetrical characteristics, such as lamps or resistors, the current
is allowed to flow through the load and the DMOS body diode. For loads such as inductive loads (motors, relays,
etc..) special care must be taken to ensure safe operation.
8.9.1
Loads with Symmetrical Polarity Characteristics
Refer to Figure 67. The following currents must be considered and limited with resistors :
•
IDS(REV) :The parasitic body diode of the power DMOS is conducting. This means that current will flow in the
•
•
ISREV_LOGIC : This current will flow in Zener ZD(AZ), which acts as a diode.
ID_ESD : Since the pin GND is at a diode voltage (ZD(AZ)) above GND and the IN pin is more or less at battery
potential, the ZDESD diode should be protected with a resistor RIN. (this is valid for all the logic pins).
IIS(REV) : Via the sense resistor, the current will flow in the ZIS(AZ) Zener which will act as a diode.
load. The load will actually limit the current in the body diode power DMOS.
•
Application Note
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App. Note
Protection
28V
28V
28V
+
VGND
+
RGND
27.3V
+
VIN RIN
VLOAD R;L;C
IN
GND
7V
-
+
+
OUT
+
VIS
ZDESD
RIS
VESD(AZ)
0.7V
-VS(REV)
-
IDS(REV)
0.7V
-
ID_ESD
ISREV_LOGIC
0.7V
IIS(REV)
ZD(AZ)
+
VZ(AZ)_D
VDS(REV)
-
-
-
+
ZIS(AZ)
IS
+
VIS(AZ)_D -
VS
reverse polarity protection.svg
0V
Figure 67
Reverse Polarity Protection with Symetrical Polarity Load. Example with 28V
8.9.2
Reverse Polarity Protection for the Load
There are many applications where the methods of protection against applied reverse polarity described above
cannot be used. Some examples are: the load is in a DMOS bridge; the load has an integrated freewheeling diode;
the load itself must be protected from wrong polarity as electrolythic capacitors; the load consists of an inductance
with PWM regulated current or the load has a small resistive component. In all of these cases, it is necessary to
block the current. To do this, the best solution is to use a Power PROFET TM. Refer to Figure 68. With the use of
a blocking element, the IREV is zero.
ECU
To other
loads
CLx
VS
BTT60xx-1EKA
- VBAT +
IN
Relay and
Fuse box
-
DEN
VS_REV_PROT
IS
GND
VS
Battery
L,
GND
GND
R,
C
+
Reverse polarity Load protection
Application Note
Smart High-Side Switches
61
Rev 0.3, 2014-10-30
App. Note
Protection
Relay and
Fuse box
ECU
BTS50015-1TAA
CLx
OUT
-
- VBAT +
VS
Battery
To other
loads
VS
VS_REV_PROT
R,
IN
L,
GND
GND
C
+
Reverse polarity Load protection.svg
Figure 68
Reverse Polarity Protection with Unsymetrical Polarity Load
Application Note
Smart High-Side Switches
62
Rev 0.3, 2014-10-30
App. Note
Diagnostics
9
Diagnostics
The diagnostic functions embedded in the PROFET™ +24V is a function getting increasing importance driven by
LED and short circuit to GND requirements. PROFET™ +24V devices use a current sense method to offer
complete diagnostic coverage over the output current range. Diagnostics are synchronized with the input, meaning
the PROFET™ +24V always provides the status of the present state of the power DMOS and the logical signal IN
i.e. there is no memory effect.
9.1
Current Sense
Current sense is implemented using a current generator which provides a current proportional to the load current
IL. The ratio between IIS and IL is called kILIS. When a failure occurs the current generator is set to IIS(FAULT), the
maximum sense current the current generator can provide. Refer to Figure 69. The current sense generator is
based on the P channel MOSFET T4. The gate of T4 is driven by op-amp OPA which set the voltage at T4 gate
equal to the output voltage. The sense feed consists of the DMOS transistor T2, which is not connected to the
output, but supplies T4 only. As with all current generators, the current sense is connected to a voltage supply,
here VS. This means that the voltage at the IS pin, VIS should always be smaller than VIS(RANGE) min, otherwise the
current generator cannot provide the required current.
The maximum current supplied by the current generator is given by the parameter IIS(FAULT). The size of T4
determines the value of IIS(FAULT). There is no current limit mechanism or thermal sensor for T4 hence the system
designer should ensure that T4 is adequate protected. T1 provides protection against over voltage and ESD by
acting as a Zener diode. One limitation of T1 is that two PROFET™ +24V with different battery feeds can not share
a common sense line. This could result in one of the PROFET™ +24V supplying the other one through transistor
T1.
VS
T3
T2
T1
Gate
driver
OUT
FAULT
DEN
OPA
T4
IS
sense for the baleze single.svg
Figure 69
Current Sense Generator
Application Note
Smart High-Side Switches
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Rev 0.3, 2014-10-30
App. Note
Diagnostics
9.2
Gate Back Regulation
PROFET™ +24Vs use gate back regulation (GBR). The aim of GBR is to improve the current sense accuracy at
low load current.
9.2.1
Influence on the Power Stage
The GBR monitors the drain source voltage VDS. As VDS is gets low, the gate driver partially reduce the gate
voltage to increase the channel resistance. VDS is limited to VDS(NL). Figure 70 graphs the VDS voltage on the left
hand side with and without GBR as a function of the load current. On the right hand side is a graph of the artificial
RDS(ON) for low load currents. These graphs are based on the BTS5020-2EKA.
1000
RDSON max
RDSON typ
100
40
RDSON (Ω)
Voltage Drop V DS (mV)
60
20
RDSON min
10
1
0,1
0
0
500
1000
1500
2000
0,01
0
Load Current (mA)
Figure 70
Gate Back Regulation Influence on Voltage Drop.1)
9.2.2
Sense Accuracy Improvement
20
40
60
80
100
Load Current (mA)
120
140
Voltage limitation .vsd
The main purpose of GBR is to improve the kILIS accuracy at low load current. Equation (15) is used to calculate
the current sense ratio kILIS where:
VOFFSET is the parasitic offset voltage of the op-amp. (it can be negative or positive)
VDS is the voltage drop in the power MOSFET which is RDS(ON) * IL.
kILIS0 is the target central value.
1
k ILIS = k iILIS0 × ------------------------------V OFFSET
1 + ---------------------V DS
(14)
From this equation, when the load current IL is going to 0, the klILIS spread is increased to infinite because VDS =
0V. GBR compensates for this behavior by limiting VDS to VDS(NL). Figure 71 provides the famous kILIS trumpet,
with and without gate back regulation.
1) Typical RDS(ON), worst case GBR
Application Note
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App. Note
Kilis ratio in %
Diagnostics
200
kilis w/o GBR
180
kilis with GBR
160
typical
140
120
100
80
60
40
20
0
10
500
1000
Load Current (mA) IL
1500
Figure 71
Gate Back Regulation Influence on kILIS accuracy, in %
9.2.3
Sense Resistor
2000
Gate back regulation .vsd
Refer to Chapter 10.3.
9.3
Short Circuit to Ground
9.3.1
Short Circuit to Ground in OFF State
Note that short circuit to GND in OFF state cannot be detected. When this failure occurs, the PROFET™ +24V
does not report a fault condition.
9.3.2
Short Circuit to Ground in ON State
A short circuit to ground in the ON state is detected by the logic as one of the three logic signals, "over current
OC", which comes from current limitation circuitry, "over temperature OT" which comes from the temperature
sensor and "over temperature swing OTS" which comes from the temperature swing sensor. As soon as one of
these three logic signals is high, the PROFET™ +24V is considered to be in a stressful situation which will result
in an activation of the sense signal IIS(FAULT).
Figure 9.4 describes the different signals involved on a large time scale, from the power DMOS transistor TMOSFET
temperature and IL load current to the logic signals shows for different failures.
OT
t sIS(OT_blank)
OTS
Short circuit
OC
Short Circuit to GND Logic .vsd
Figure 72
Short Circuit to GND Logic
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Diagnostics
9.4
Short Circuit to Battery
9.4.1
Short Circuit to Battery in OFF State
During a short circuit to the battery in OFF state, the output voltage of the PROFET™ +24V rises up to VBAT.
PROFET™ +24V have an embedded comparator to monitor the output voltage. If this voltage rises above VOL(OFF),
the device considers this as a fault condition and sets the sense signal accordingly. To prevent parasitic short
circuit to battery diagnostic when the ouput is floating (open load), an external pull down resistor RSC_VS = 47kΩ is
recommended. Refer to Figure 73.
Vbat
VS
IIS(FAULT)
SHORT CIRCUIT
TO BATTERY
OL
comp.
IS
OUT
+
GND
VOL(OFF)
RIS
RGND
RSC_VS
Short circuit to Vs.svg
Figure 73
Short Circuit to Battery Detection Hardware Set up
9.4.2
Short circuit to Battery in ON State
A short circuit to battery in the ON state is more difficult to diagnose. Fortunately, the consequence of such an
event is simply that the sense current IIS is lower than expected. Depending on the short circuit impedance, it will
be diagnosed as open load in ON or under-load. A discriminating diagnosis should then be performed in the OFF
state.
9.5
Inverse Current
Inverse current is similar to short circuit to battery. Nevertheless, parasitic inverse current can bring additional
challenges to be overcome. Refer to Figure 74. If the inverse current is too high, a parasitic current IIS_INV will flow
at the sense pin IS.
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App. Note
Diagnostics
IN
IN
CASE 1 : Switch is ON
CASE 2 : Switch is OFF
OFF
ON
t
IL
NORMAL
t
IL
NORMAL
NORMAL
NORMAL
t
t
INVERSE
INVERSE
DMOS state
DMOS state
OFF
ON
t
t
IS
IS
IL / kilis
[email protected] ~ 0
Z
IL / kilis
SC VBAT
Z
t
IN
t
IN
CASE 3 : Switch ON into inverse
OFF
OFF
ON
ON
t
t
IL
IL
NORMAL
CASE 4 : Switch OFF into inverse
NORMAL
NORMAL
NORMAL
t
t
INVERSE
INVERSE
DMOS state
DMOS state
OFF
ON
ON
OFF
t
t
IS
IS
Z
[email protected]
[email protected]
~0
IL / kilis
IL / kilis
t
[email protected]
~0
SC VBAT
Z
t
Inverse conditions.svg
Figure 74
Inverse Current Diagnostic
9.6
Open Load
9.6.1
Open Load in OFF State with Bulb and Inductive Load
During the OFF state, open load can be diagnosed using an external pull up resistor ROL. Open load in OFF is
detected using a comparator to check the output voltage. In normal operation, the load acts as a strong pull down.
When the load connection is lost or the load blown, the output voltage is pulled up to the battery voltage through
ROL. An additional switch is usually necessary to reduce the stand by power consumption of the module during
parking to prevent a permanent leakage current VBAT / ROL from flowing in the load. A PNP transistor, T1 such as
a BC807 will fit this requirement. This transistor can be shared by other devices which share the same battery
feed. The value of ROL depends on the OEM specified minimum parasitic impedance RDIRT. As a good reference,
Infineon considers RDIRT as open load impedance 4.7kΩ as a minimum value.
Knowing RDIRT, ROL can be obtained by the following Equation (15) where VBATMIN is the minimum battery voltage
during which the open load in ON diagnostic is performed. Refer to Chapter 13.2 for detailed calculation.
1
R OL < R DIRT × -------------------------------------V BATMIN ⎞
⎛ ----------------------–1
⎝ 3V
⎠
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Diagnostics
ROL should be large enough to ensure that the power loss in this resistor can be neglected. Assuming a maximum
PRMAX of 250mW (pulsed during the open load diagnosis) ROL is defined by Equation (16).
2
2
V BAT
V BAT
R OL > ----------------- = ---------------P RMAX
0, 25
(16)
ROL = 1.5kΩ is recommended value.
Vbat
T1
VS
IIS(FAULT)
ROL
OL
comp.
OUT
IS
+
ILOFF
GND
RIS
VOL(OFF)
RGND
RDIRT
Open Load in OFF.svg
Figure 75
Open Load in OFF Hardware
9.6.2
Open Load in OFF State with LED Module
LED modules are quite challenging to diagnose in OFF state. On one hand, the leakage current of the dirt
resistance is in the mA range. On the other hand, 10µA is sufficient to illuminate an LED. The only way to diagnose
either a standard or advanced LED module is to guarantee the voltage VOUT is below the illumination level. To
achieve this, the LED module must have a resistor ROL_LED at the input. Refer to Figure 25 and Figure 26. This
resistor is polarized by the ROL. In case of open load, the ROL will pull up the voltage as in the case of bulb. In
normal conditions, the ROL_LED will sink the current and limit the output voltage below the LED illumination
threshold.
9.6.3
Open Load in ON state
To determine if a PROFET™ +24V can diagnose an open load in the ON state, it is necessary to precisely define
the characteristics of this condition. As described earlier, an open load in an automotive environment is the
resistance ROL as a minimum. In the case of an LED module powered from a DC/DC converter, if one LED is
blown, the DC/DC converter will still consume some current. This current is defined by the OEM. As a good
reference, Infineon considers an open load to be a current in between of 5 to 30mA. When the open load current
range has been defined, it is easy to determine the minimum sense current considered to be an open load, using
the current sense specification. Figure 76 and Table 12 shows an give open load currents considered.
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Diagnostics
.
I IS
IIS(OL)
IL
IL(OL)
Sense for OL .vsd
Figure 76
Current Sense Accuracy at Small Load
Table 12
PROFET™ +24Vs Open Load Definition
50mΩ
kILIS ratio typical
IIS(OL) (µA)
IL(OL) min (mA)
IL(OL) max (mA)
9.7
1500
8
5
30
Partial Loss of Load
Some applications use loads in parallel which can lead to partial loss of load. Refer to Figure 77.
9.7.1
Partial Loss of Load during OFF state
During the OFF state, a partial loss of load caused by losing one out of X loads cannot be detected.
9.7.2
Partial Loss of Load during ON state
During the ON state, diagnosis of the loss of one out of X loads can be realized using the current sense function.
Accuracy of the PROFET™ +24V, as well as the complete system accuracy can challenge the diagnosis. To
answer the question "can you diagnose the loss of xW, out of yW", it is necessary to determine the following as
described in Figure 77. Red color indicates min typical and max with one load loss, Green color indicates min
typical and max with nominal load.
Step 1, Which lamps are used? Different lamps have different accuracies. Refer to Chapter 5.1.
Step 2, Supply voltage range. Lamp current changes with supply voltage. Refer to Chapter 5.1
Step 3, Ground shift range. Refer to Chapter 3.5
Step 4, If PWM used and the PWM accuracy. Refer to Chapter 7.6
Step 5, Current sense conversion, kILIS accuracy?
Step 6, Eventual additional leakage current on the sense line?
Step 7, Sense resistor accuracy?
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Diagnostics
Step 8, A/D converter accuracy ? A/D converter reference voltage, A/D resolution and LSB error?
ILL
IL 2) Load current dependency to supply voltage
ΔV
1) Unaccuracy of the load
Δ
P
IL
3) Load current dependency to GND shift
2
1
ΔGND
Vbat
IL
Vbat
5) Current Sense Error
IL
Vbat
4) Load current dependency to PWM
missmatch
3
4
ΔkILIS
ΔPWM
5
Vbat
IL
Vbat
VSENSE 7) Current Sense Resistor error
6) Current Sense Line offset
bits
6
8) A/D error
7
Δlk
ΔR
Δ A/D
Vbat
Vbat
Vbat
longstoryshort .vsd
Figure 77
Diagnostic of Partial Load Loss
When all of this information is known, it is possible to determine if the PROFET™ +24V can diagnose a partial loss
of load. Table 13 gives the required PROFET™ +24V kILIS accuracy to detect the loss of specific partial loads.
Table 13
PROFET™ +24V Planned Load and Diagnosis
50mΩ
Load
2 x 21W
Target diagnostic
21W
Accuracy
10% @ 2A
9.7.3
Current Sense Accuracy Improvement
Sometimes, the current sense accuracy is not good enough to diagnose a required loss of load. In this case,
PROFET™ +24V devices offer a calibration strategy. In details, it means the application should “learn” the real
kILIS ratio of the given device soldered on the PCB. This value should be stored in a non volatile memory. Figure 78
describes in details the reasons for unaccuracy and compensation effects.
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Diagnostics
IS
1/ Everything ideal
2/ Missmatch in the cells
IS
1
3/ Offset influence
IS
2
IL
IL
IL
3
IS
6a/ One point calibration
5/ Real GBR compensation
IS
5a
4/ Ideal GBR compensation
4
IL
IL
IL
IS
IS
6b/ Two points calibration
5b
IL
Figure 78
longstoryshort _empirestricksback .vsd
Calibration Strategy to Improve Current Sense Accuracy
Drawing 1 describes the ideal behavior expected. The load current is recopied with a certain reduction factor kILIS.
Drawing 2 provides the missmatch in the number cells. Going back to Figure 69, the ratio between the number of
cells of T1 and T2 give the kILIS factor. A missmatch in the cells of T1 and / or T2 causes the kILIS factor to be
different to the expected theoretical value. Drawing 3 describes the influence of the non perfect offset of the opamp.
Drawing 4 shows the offset compensation via G.B.R. Drawing 5 exhibits the kILIS accuracy the device can provide
over temperature, production spread, supply voltage etc...
Drawing 5a demonstrates the benefit of one point calibration. During testing of the module, the micro controller
learns the real sense current IIS_REAL, at a known IL_ CAL load current for calibration. The current sense is then
guaranteed to be in a conic stripe. The calibration in this case is compensating the offset of the op-amp.
Drawing 5b demonstrates the benefit of a two points calibration. Knowing IIS_REAL1 and IIS_REAL2, giving resp. IL_CAL1
and IL_CAL2, the current sense is then guaranteed to be in stripe. On top of the offset compensation, the calibration
procedure has compensated the missmatch in the kILIS factor.
9.8
Current Sense and PWM
(Refer to Chapter 7.6 for details). During PWM, the application still requires diagnosis. Of primary importance is
short circuit to GND information which is used to limit the number of short circuit events. (Refer to Chapter 8.2.7).
PWM usage with current sense diagnosis can be limited by the inherent timing limitations of PROFET™ +24V.
The aim is to give valid current sense information as fast as possible.
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Diagnostics
tsIS(ON), the time required for the IN pin to transition from LOW to HIGH limits the minimum ON time necessary to
get valid sense information. tsIS(FAULT) also limits the minimum ON time to get valid short circuit information.
Table 14 sums up the minimum PWM duty cycle which can be used with a PROFET™ +24V.
Table 14
PROFET™ +24V PWM Timing Limitation
Parameter
Period
min duty cycle at the output
min duty cycle at the output for
diagnostic
Symbol Formula
fPWM =
fPWM =
fPWM =
fPWM =
100Hz
200Hz
400Hz
1kHz
5
2.5
1
ms
1.4
2.8
7
%
3
6
15
%
TPWM
1/fPWM
10
dOUT_MIN tOFF_delay/TPWM 0.7
dMIN
tsIS(FAULT) /T
1.5
Unit
When the current is established in the Power DMOS, the sense signal IIS takes far much lower time to establish.
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The Micro Controller Interface
10
The Micro Controller Interface
10.1
GND Pin
Although the GND pin is not directly interfaced to the micro controller, GND is of primary importance in controlling
a PROFET™ +24V. Figure 79 shows the ideal GND protection circuitry. What ever the GND circuit chosen in the
application, this circuit can be shared with other devices having the same battery feed and only with these ones.
•
•
•
Region 1. For current in the magnitude of operating current (10mA or below), the voltage drop should be kept
to a minimum as a shift in the PROFET™ +24V GND potential leads to a shift in the input threshold.
Regions 2. To provide overvoltage protection for voltages above the breakdown voltage, the current through
the Zener diode ZD(AZ) must be limited to a few tens of milliamps. This limit does not apply for ESD protection.
Region 3. This ensures the necessary current limitation when reverse polarity is applied. The current in this
mode should be as low as possible (below IGND) to reduce the loss generated in the diode ZD(AZ).
IGND
2
10mA mini
GND
IGND
1
+
VGND
VGND
-
As small as possible
3
As small as possible
At worst 1.2V
GND ideal circuitry. vsd
Figure 79
Ideal GND Circuitry
10.1.1
GND Resistor
A compromise must be found in the GND resistor value which approximates the different regions of the above
characteristic. For over voltage (refer to Chapter 8.8) and reverse polarity (refer to Chapter 8.9) protection, the
value of the GND resistor should be as high as possible. The upper value is restricted by the ground shift potential
(VGND = RGND x IGND) caused by the operating current flowing via the GND pin. In practice, a value of 150Ω per
chip protected has proven satisfactory.
The main disadvantage of the GND resistor is high power dissipation in the event of an applied reverse polarity
(VS(REV)² / RGND). This leads to a relatively large resistor on the PCB. With 16V, 1.7W. 1206 package is necessary.
A capacitor can be used in parallel with the resistor which to limit the influence of IGND variation during switching
of the channel. A capacitor placed between VS pin and GND will filter the charge pump perturbations.
10.1.2
GND Diode
To protect against reverse polarity events, a diode can be used. The reverse voltage is limited by the reverse
breakdown voltage of the diode or the losses in the PROFET™ +24V generated by the load current. A suggested
diode is the BAS52-02V. The diode approximates only regions 1 and 3 of Figure 79 and does not protect against
over voltage or loss of battery. To improve the over voltage event, a 27Ω resistor can be used in serial to the diode
to limit the current. Refer to Chapter 8.5. In this particular case, a 1kΩ resistor can be used in parallel with the
diode. PROFET™ +24V are then limited in case of over voltage.
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10.1.3
Different Ground for One System
At least two different Grounds are defined at a system level and usually three are necessary for optimum design.
The chassis GND is the system 0V reference. The module GND is the 0V module reference. The module GND is
sometimes split into digital GND (reference voltage for the digital sections such as the voltage regulator, micro
controller, A/D converter, CAN transceivers etc.) and power GND (reference voltage for the power elements such
as LSS, HSS, H bridges etc.). A fourth GND can also be defined which corresponds to the device GND. These
different GNDs are shown in Figure 80. For simplification it doesn't describe the redundancy of GND wiring
connection as shown in Figure . In a real system, the GND schematic can be even more complicated!
VBAT
VBAT
OUT
Vcc
μC
GND
OUT
I/O
I/O
Vcc
IN
I/O
DEN
I/O
A/D
IS
μC
DEVICE
GND
GND
I/O
I/O
IN
DEN
DEVICE
GND
I/O
A/D
IS
GND
circuit
DIGITAL
GND
GND
circuit
ANALOG
GND
COMMON
MODULE GND
GND SEPARATED
MODULE GND
ANALOG GND
DIGITAL GND
CHASSIS
CHASSIS
Figure 80
GND Definition
10.1.4
Loss of Ground
GND concept.svg
According to Figure 80, up to four GND can be lost. In case of module GND loss, the PROFET™ +24V
automatically turns OFF or remains OFF. In case of analog or device loss of GND, the micro controller can play
the role of a parasitic GND via the logic inputs. To avoid this, a serial resistor (e.g 4.7kΩ) should be placed in
between each micro controller and PROFET™ +24V interfaces.
10.2
Digital Pins
All the digital pins of PROFET™ +24V are identical. The digital pins are voltage driven. An internal current source
is used to default the digital pins to logic level 0. Where a pin is not required, it is recommended to leave it open.
If this is not done, the ESD diode can be destroyed.
In binary digital circuits, there are two distinct voltage levels which represent the two binary states. In order to allow
for the inevitable components tolerances, two voltage ranges are usually defined to represent these states. As
shown in Figure 81, if the signal voltage lies in the range VIN(AMR)min to VIN(L), it is interpreted (by the power device)
as a logic 0. If the signal voltage falls in the range of VIN(H) to VIN(AMR)max, it is interpreted as a logic 1. The two
voltage bands are separated by a region in which the logic state is undefined. Voltages in this undefined region
should be avoided.
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DESTRUCTION
VIN(AMRmax)
VIN(H)
LOGIC 1 = ACTIVATION
VIN(L) UNDEFINED
LOGIC 0 = INHIBITION
VIN(AMRmin)
DESTRUCTION
input voltage.vsd
Figure 81
Two Distinct Voltage Ranges used to Represent two Values of Binary Variables
10.2.1
Absolute Maximum Rating
During two normal conditions, absolute maximum rating on input pins can be met.
Figure 82 describes the reason for the 6V absolute maximum rating. During the OFF state of the module, where,
the voltage regulator is OFF, a wake event is generated either by the communication (eg CAN, LIN, etc...), or by
a digital input. In such a case, the voltage at the I/O of the micro controller is limited by the Zener diode at the VDD
line and the ESD structure internally the micro controller. The current is limited by the serial resistor.
.
LDO is OFF (module in sleep mode )
LDO
VBAT
PROFET
Suppressing diode
min 5.5 max 6V
TM
+
VDD
+
VDD
Digital contact
Eg : door open
VDD
VBAT
-
CTC
~100μA
28...100k
+
+
68k
VBAT
1k
(wetting current)
-
6.5V
Micro controller
6V for I_0 pins.svg
Figure 82
Normal Application Condition to reach Absolute Maximum Rating
As shown in Figure 83, in order to activate the channel, it is necessary to pull the input pin up to VBAT, as it cannot
be assumed that the voltage regulator is operating. Nevertheless, the voltage at the input should not exceed 6V
permanently. To bypass the microcontroller, the easiest way is to use two diodes, such BAV 70S, in an OR
combination. The battery voltage is divided by resistor RLH1 and RLH2. A ratio of 1/6 will guarantee that even with
36 V battery voltage, the input pin will not see more than 6V while a low battery voltage case such as 8V will
provide sufficient voltage at the input to guarantee the switching ON.
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The Micro Controller Interface
VBAT
RLH1
Limp home logic
RLH2
VDD
PROFETTM +
RI/O
GPIO
+
IIN
IN
+ Vdrop +
LOGIC
IIN(H)
VIN
Micro controller VI/O
GND
-
-
+
IGND
VGND
ZGND
Limp Home for input.svg
Figure 83
Limp Home Scenario
10.2.2
High level input voltage
With an input signal in this region, the digital circuitry will determine the input to be a high logic level and thus will
turn the output ON or keep it ON. The application must ensure that the minimum voltage applied to the input pin
is higher than VIN(H) to guarantee an ON condition. The micro-controller specification usually provides the minimum
output voltage for a logic 1 signal. As a good reference, Infineon considers VIN(H)_MIN = 3.6V. Adding a resistor RI/O
between the micro-controller and the power device is recommended. However, the voltage drop across this
resistor must also be considered in the design. The equivalent circuit is described in Figure 84 where the VIOMIN
value defined by Equation (17) must be guaranteed.
V IOmin = V IN ( H )min + R IO × I INmax + Z GND × I GND
(17)
All parameters are given in the respective datasheets. Please note that the voltage drop caused by the resistor
RI/O severely limits the number of devices which can be driven from one I/O pin of the microcontroller.
VDD
PROFETTM +
RI/O
GPIO
+
IIN
IN
+ Vdrop +
LOGIC
IIN(H)
VIN
Micro controller
VI/O
GND
-
IGND
VGND
ZGND
-
-
Figure 84
+
High level Equivalent Circuit
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The purpose of the IIN(H) current source is to guarantee the device is OFF when the micro controller pin is floating,
(e.g. during reset, un-powered, etc...).
10.2.3
Undefined region
The undefined region contains the switching thresholds for ON and OFF. The exact value VTH where this switching
takes place is unknown and dependant on the device manufacturing process and temperature. To avoid crosstalk and parasitic switching, hysteresis is implemented. This ensures a certain immunity to noise.
This noise immunity can be defined, assuming that the exact turn ON and turn OFF thresholds are known. As an
example, a rising or falling signal with parasitic noise will see several ON / OFF states before going to a stable
state. Figure 85 gives an example of this situation. At turn ON, the parasitic noise is sufficiently intrusive to turn
the device ON and OFF. At turn OFF, the parasitic noise is filtered by the hysteresis circuitry. The bigger the
hysteresis, the higher the immunity to noise, but the difference between VIN(H)_MIN and VIN(L)_MAX also increases,
limiting the application's range. PROFET™ +24V use a typical hysteresis voltage of 200mV.
VIN
VIN(hysteresis)
VTH
t
OFF
ON
Figure 85
ON
OFF
OFF
parasitic input voltage.vsd
Benefit of the Hysteresis for Immunity to Noise
The hysteresis value is not tested during production, due to the test complexity.
10.2.4
Low level input voltage
With an input signal in this region, the digital circuitry will determine the input to be a low logic level and thus will
turn the output OFF or keep it OFF. The application must ensure that the maximum voltage applied to the input
pin is lower than the VIN(L)max voltage to guarantee an OFF condition. As a good reference, Infineon consider
VIN(L)_MAX = 1.1V. Refer to Figure 86 for details.
The equivalent circuit is described in Figure 86 where the VIOmin value defined by Equation (18) must be
guaranteed.
V IOMAX = V IN ( L )MAX + R IO × I INmax + Z GND × I GND
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The Micro Controller Interface
VDD
PROFETTM +
RI/O
GPIO
+
IIN
IN
LOGIC
+ Vdrop +
IIN(L)
VIN
Micro controller
GND
VI/O
+
VGND
IGND
ZGND
-
-
Low level input voltage.svg
Figure 86
Low level Equivalent Circuit
10.3
Sense Pin
As described in Chapter 9.1, the current sense function is driven by a current generator. The sense pin is a
combination of two current generators, one for nominal conditions and one for fault conditions. Micro-controllers
measure voltage, not current hence a sense resistor is required. To find the value of the sense resistor RIS, it is
important to know the maximum load current amplitude the system is required to diagnose.
10.3.1
Maximum Load Current
To define the maximum current IL(NOM)_MAX which can flow in the power DMOS, a solution is to define the minimum
PWM duty cycle at the maximum battery voltage. For example, assuming a duty cycle of 8% as a minimum
functionality (as an example for lamp dimming) and a maximum 36V battery voltage, it is equivalent to start the
PWM at a battery voltage of 10.2V. Determining the lamp resistance at 10.2V, out of Equation (1), it is possible
then to determine the maximum current which flows at 36V battery voltage. Refer to Figure 87 with a 2x21W bulb
example. Out of the graph, it is seen the maximum current which can flow in a 2x21W during a PWM of 8% at 36V
is roughly 4.2A. A system using BTT6050-2EKA to drive 2x21W bulb should be able to diagnose 4.2A current.
With IL(NOM)_MAX known, the minimum current ratio, kILIS_MIN at this point can be determined. With this value, the
maximum sense current the PROFET™ +24V can provide is IIS_MAX is known. All current above this value will be
considered as a short circuit. Taking into account the micro controller supply VDD, the maximum sense resistor is
RIS = VDD / IIS_MAX. Refer to Figure 88 and Table 15.
Note that the PROFET™ +24V current sense range is limited by the maximum current the P channel MOSFET
can provide. Refer to Figure 69. Table 16 summurizes the maximum load currents PROFET™ +24V devices can
diagnose.
Table 15
Optimized RIS calculation example
50mΩ
Load planned (W)
2 x 21
Load current max (A)
4.2
kILIS mini
RIS (kΩ)
1305
Application Note
Smart High-Side Switches
1.5
78
Rev 0.3, 2014-10-30
App. Note
The Micro Controller Interface
4,5
Lamp current in dimming
4
Lamp current in power limitation
Load current (A)
Lamp current in DC
3,5
3
2,5
2
1,5
1
18
24
30
36
Battery Voltage (V)
Figure 87
Maximum Current with 8% PWM Function of the Battery Voltage. 2x21W Lamp
16
I sense all max
I sense max I fault min
14
I sense typical
Sense Current IIS (mA)
I sense min I fault max
I sense all min
12
10
8
6
4
2
0
0
20
40
60
Load Current I L (A)
80
100
current sense current .vsd
Figure 88
Sense Current Function of the Load Current with BTT6020-1EKA
Table 16
PROFET™ +24Vs Maximum Diagnosable Current
12mΩ
20mΩ
30mΩ
50mΩ
100mΩ
200mΩ
Target Load (W)
2 x 70W
5 x 21W
1 x 70W
4 x 21W
1 x 70W
3 x 21W
2 x 21W
21W
2 x 5W
Maximum current with 8% PWM (A)
14
8.5
6.5
4.2
2.1
1.5
kILIS ratio typical
4000
3000
2150
1500
1500
550
Diagnosable load current ILMAX (A)
24
15
11
8
8
2.8
Application Note
Smart High-Side Switches
79
Rev 0.3, 2014-10-30
App. Note
The Micro Controller Interface
10.3.2
Minimum Load Current
The minimum load current the PROFET™ +24V devices will experience is the open load. As described in
Chapter 6.3 and Chapter 9.6.3, in that case, the minimum current IIS(OL) shall be too small to be detectable by the
RIS defined in Chapter 10.3.1. In such a case, the usage of an additional sense resistor RIS_LOWLOAD and a switch
has to be considered. Figure 89 sketches the circuitry to be employed. A suggested value for RIS_LOWLOAD is 10kΩ.
+
VS
VDD
PROFETTM +
+
Micro controller
IS
IIS
A/D
+
+
RA/D
VS
VDD
RIS
VA/D
RIS_LOWLOAD
VIS
I/O
-
-
low high load current switch.svg
Figure 89
Low Load Current Detection Circuitry
10.3.3
Sense Pin Voltage
The sense pin has no particular clamping structure, except the ESD structure, referenced to VS. It means if no
external limitation is applied, VIS can go up to VS. Refer to Figure 90. To protect the micro controller, a serial
resistor is necessary, as a minimum. In that case, the micro controller protection diode will limit the voltage while
the serial resistor will limit the current.
Application Note
Smart High-Side Switches
80
Rev 0.3, 2014-10-30
App. Note
The Micro Controller Interface
+
VS
IIS_LIN
IIS_FAULT
VDD
+
VS
μC
IS
VDiode
IA/D
-
+
VDD
A/D
VA/D
RA/D
IIS
+
+
+
RIS
VA/D
VIS
-
-
-
sense for the baleze single.svg
Figure 90
Current Sense Circuitry and Minimum Protection Circuitry
It is also possible to use a Zener diode to clamp against over voltage. This improves the over voltage robustness
of the system. Refer to Figure 91. The IA/D is dramatically reduced and most of the voltage is clamped by the Zener
diode. RSENSE is necessary to protect the sense structure from destructive power dissipation under normal
conditions and from reverse polarity.
+
VS
IIS_LIN
IIS_FAULT
VDD
VS
+
μC
IS
VDiode
VDD
-
+
VA/D
+
IA/D
-
RA/D
A/D
+
IZ
+
VA/D
VZ
VSENSE
RSENSE
+
RIS
-
IIS
+
-
VIS
sense for the baleze single improved.svg
Figure 91
Current Sense Circuitry with Improved Protection Circuitry
It is important to notice the power in the sense circuitry (IIS_LIN; IIS_FAULT) is not negligible, thus the VIS should not
be limited, either by too low sense resistor, either by Zenering.
Application Note
Smart High-Side Switches
81
Rev 0.3, 2014-10-30
App. Note
PROFET™ +24V Flexibility
11
PROFET™ +24V Flexibility
Among the features set offered by PROFET™ +24V, pinout compatibility within the familly is one of the most
important.
Three packages, in four different variants are proposed. Refer to Figure 92
Figure 92
PROFET™ +24V Packages
11.1
Pinout Logic
The pinout logic is always the same. On right hand side are found the ouptut(s) of the PROFET™ +24V. On the
left hand side are found the connection to the micro controller. Supply comes from the bottom i.e. from the slug.
11.2
Single and Dual
Refer to Figure 93. Compatibility between single and dual channels is possible if the heat slug is planned for within
the PCB layout.
NC
1
14
NC
2
13
NC
GND
GND
1
3
14
12
OUT0
IN
IN0
4
2
DEN
DEN
5
IS
IS
6
NC
DSEL
5
7
VS
VS
NC
OUT
11
13
OUT0
OUT
12
10
OUT0
OUT
9
11
NC
NC
10
8
OUT1
NC
SO14 EP
IN1
6
NC
7
9
OUT1
8
OUT1
SO14 EP
pinout dualSO 14singleSO 14 - Truck.vsd
Figure 93
Pinout Compatibility between Single and Dual Channels
Application Note
Smart High-Side Switches
82
Rev 0.3, 2014-10-30
App. Note
PROFET™ +24V Scalability
12
PROFET™ +24V Scalability
PROFET™ +24V belongs to a family. Every electrical parameter is scaled around the RDS(ON) value. The RDS(ON)
value scales mainly kILIS ratio, EAS capability and IL(SC) current limitation. All other parameters are identical!
12.1
Family Summary
Table 17 summarizes the difference between the PROFET™ +24V.
Table 17
Difference in High Ohmic Family
Number
Parameter
Symbol
BTT 6050
Unit
Overview
Load
2 x 21
W
Overview
Typical kilis ratio
1500
-
P_4.1.22
Maximum power
1.6
W
P_4.1.23
Inductive energy
40
mJ
P_4.3.2
Junction to ambient
35
K/W
P_5.5.1
P_5.5.21
On state resistance
PLOAD
kILIS
PTOT
EAS
RthJA
RDS(ON)
100
50
mΩ
P_5.5.2
P_5.5.3
Nominal load current
5
3
A
P_5.5.9
Inverse current
capability
Inom1
Inom21)
-IL(INV)1)
3
A
P_5.5.19
0.6
mJ
0.7
mJ
P_6.6.4
EON
Switch OFF energy
EOFF
Load current limitation IL5(SC)
38
47
56
A
P_6.6.7
Load current limitation IL28(SC)
16
A
P_7.5.2
Open load threshold in IIS(OL)
ON state
8
µA
P_7.5.9
IL for kILIS1
IL1
0.5
A
P_7.5.10
IL for kILIS2
IL2
1
A
P_7.5.11
IL for kILIS
IL3
2
A
P_7.5.12
IL for kILIS4
IL4
4
A
P_5.5.20
Switch ON energy
1) For dual channel only
12.2
Comparison Between Truck and Car Family
PROFET™ +24V belongs to the larger family of PROFETTM + devices in which can be found the PROFETTM +12V
devices. A key benefit is the complete compatibility, in terms of package pin-out between the two families.
The devices differs electrically from each other to some few parameters. Table 18 summarizes the difference
between the BTT6050-2EKA PROFET™ +24V, BTS5030-2EKA and BTS5045-2EKA PROFETTM +12V.
Application Note
Smart High-Side Switches
83
Rev 0.3, 2014-10-30
App. Note
PROFET™ +24V Scalability
Table 18
P_
Difference between PROFETTM+12V and PROFETTM + 24V
Parameter
Symbol
BTT 60502EKA
BTS 50302EKA
BTT 50452EKA
Remarks
Voltage parameters are
changed to fit the system
requirements.
Voltage Related Parameter
4.1.1
Supply Voltage
VS
36V
28V
28V
4.1.2
Reverse polarity
voltage
VS(REV)
28V
16V
16V
4.1.3
Supply voltage for
short circuit protection
VBAT(SC)
36V
24V
24V
4.1.12 Supply voltage for
Load dump protection
VS(LD)
65V
41V
41V
4.1.26 Voltage at power
transistor
VDS
65V
41V
41V
4.2.1
VNOM
8...36V
8...18V
8...18V
4.2.2. Extended operating
voltage
VS(OP)
5...48V
5...28V
5...28V
5.5.5
6.6.3
7.5.3
VDS(AZ)
VS(AZ)
VIS(AZ)
65V...75V
41V...53V
41V...53V
5.5.14 Turn ON
tON
150 µs
230 µs
230 µs
5.5.15 Turn OFF
tOFF
150 µs
230 µs
230 µs
5.5.11 Slew rate turn ON
dV/dtON
0.3 ...
1.4V/µs
0.1 ...
0.5V/µs
0.1 ...
0.5V/µs
5.5.12 Slew rate turn OFF
dV/dtOFF
0.3 ... 1.4
V/µs
0.1 ... 0.5
V/µs
0.1 ... 0.5
V/µs
5.5.19 Switching energy ON
EON
0.6 mJ @
12Ω
1.2 mJ @
4Ω
0.8 mJ @
6Ω
0.5 mJ @
12Ω
1.1 mJ @
4Ω
0.7 mJ @
6Ω
Nominal operating
voltage
Clamping Voltages
They are the results of the
scaling from 12V to 24V
system and are not related
to any specific product.
Note that PROFET™
+24V can be used in a 12V
system.
Switching parameter
5.5.20 Switching energy OFF EOFF
PROFET™ +24V benefits
from the last know how of
Infineon in terms of EMC
capability. It offers a faster
switch ON (~3times) with
similar EMC performance.
It allows applications with
relative high PWM
frequency (up to 500Hz)
Current Consumption
4.2.5
Operating current,
one channel
IGND_1
9 mA
6 mA
6 mA
4.2.6
Operating current,
two channels
IGND_2
12 mA
8 mA
8 mA
20 µA
20 µA
4.2.10 Standby current
IS(OFF)_150 10 µA
PROFET™ +24V needs a
bit higher current to supply
the EMC circuits.
PROFET™ +24V benefits
from the last know how of
Infineon in terms of
leakage current control.
Protection
6.6.4
Load current limitation
IL5(SC)
38...56 A
36...57 A
25...40 A
4.1.4
Short circuit
Robustness
nRSC1
100 k
100 k
100 k
EAS
55 mJ
50 mJ
35 mJ
4.1.23 Maximum energy
dissipation
Application Note
Smart High-Side Switches
84
The 50mΩ PROFET™
+24V is equivalent to a
30mΩ PROFETTM 12V
from maximum switchable
current
Rev 0.3, 2014-10-30
App. Note
PROFET™ +24V Scalability
Table 18
P_
Difference between PROFETTM+12V and PROFETTM + 24V
Parameter
Symbol
BTT 60502EKA
BTS 50302EKA
BTT 50452EKA
Remarks
The 50mΩ PROFET™
+24V is equivalent to the
45mΩ PROFETTM 12V
from DC current point of
view
Load Current
5.5.2
Nominal load current
one channels
IL(NOM)_1
4.5A
6A
4.5A
5.5.3
Nominal load current
two channels
IL(NOM)_2
3A
4A
3A
7.5.9
Current Sense Ratio
kILIS
1500
2150
1500
Out of Table 17 perspective, it can be observed that the performance of PROFET™ +24V is a mixture between
two RDS(ON) performance of PROFETTM + 12V.
The load current is linked to the thermal performance and therefore, similar RDS(ON) value should be used for
comparison. Consequently, the current sense is similar. Refer to Chapter 10.3.
The short circuit current and energy capability are linked to the DMOS volume and a 50mΩ High voltage is similar
to a 30mΩ Low voltage. Refer to Chapter 7.1.
The switching speed of the PROFET™ +24V enables application such as valve controls, and can be considered
even into a 12V system
Application Note
Smart High-Side Switches
85
Rev 0.3, 2014-10-30
App. Note
Appendix
13
Appendix
13.1
PWM Power Losses Calculations
(19)
P PWM = P RON + P SW
Power losses are splitted in losses during RDS(ON) phases PRON and switching phases PSW.
(20)
2
P RON = R DSON × I PWM
× t ON × F
Power losses in the RDS(ON) phases depends on the PWM frequency F, the time ON tON, the RDS(ON) and the load
current IPWM.
(21)
V PWM 2
d = F × t ON = -----------------2
V BAT
The duty cycle is dependant on the VPWM voltage where PWM starts (usually 13.2V) and the effective battery
voltage VBAT.
(22)
2
I
2
PWM
P RON = R DSON × F × V PWM × --------------- = K 1 ×
2
V BAT
2
I PWM
--------------2
V BAT
Replacing Equation (21) in Equation (20), and defining a constant value K1 to simplify the term.
(23)
V BAT
I PWM = ------------------R LAMP
The load current IPWM is depending on battery voltage VBAT and RLAMP, resistor of the lamp, constant due to PWM.
(24)
2
K1
K 1 × V BAT
--------------------------------------------------------- = K2
P RON =
=
2
2
2
R LAMP
V BAT × R LAMP
Replacing Equation (23) in Equation (22), and defining a constant value K2 to simplify the term, power losses in
the RDSON phase is constant!
Application Note
Smart High-Side Switches
86
Rev 0.3, 2014-10-30
App. Note
Appendix
(25)
1 V BAT I PWM
P SW = 2 × P SWON = 2 × t SWON × --- × --------------- × --------------2
2
2
Switching losses PSW are twice the PSWON (assuming switch ON and OFF is symetric).
(26)
2
V BAT
1
P SW = t SWON × --- × ------------------4 R
LAMP
Replacing Equation (23) in Equation (26)
(27)
2
P SW = K 3 × V BAT
PSW is depeding on the VBAT².
2
P PWM = K 2 + K × V BAT
3
Replacing Equation (24) and Equation (27) in Equation (19)
13.2
Open Load Resistor Calculation
The maximum acceptable value for ROL, (open load pull up resistor) is searched for.
R DIRT
V BAT – 3V < ---------------------------------- × V BAT
R DIRT + R OL
The voltage at the output VOUT should be higher than the highest voltage possible understood as a present load.
This voltage is given by the voltage divider formed by RDIRT and ROL.
V BAT × ( R DIRT + R OL ) – 3V × ( R DIRT + R OL ) < R DIRT × V BAT
Enlarging the equation,
( V BAT – 3V ) × R OL < 3V × R DIRT
Symplifying and bringing ROL on the right hand side.
Application Note
Smart High-Side Switches
87
Rev 0.3, 2014-10-30
App. Note
Revision History
Table 19
Revision History
Version
Date
0.0
2012-12-24
Initial Creation of the Document
0.2
2013-01-13
Creation of public version
0.3
2014-11-19
Application Note
Smart High-Side Switches
Chapter
8.2.5
8.2.6
Change
Change of text and Fig 53
Changed Fig 54
88
Rev 0.3, 2014-10-30
Edition 2014-10-30
Published by
Infineon Technologies AG
81726 Munich, Germany
© 2014 Infineon Technologies AG
All Rights Reserved.
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