SiDB766761

SiDB766761
Vishay Siliconix
Temperature Sensing MOSFET Evaluation Board
FEATURES
Turns Off MOSFET Before TJ Exceeds 175_C Rating
5-V Logic Level Operation of Control Circuit
12-V Battery Level Operation of Power MOSFET Circuit
Sense Diode Bias Current, IF = 250 A
Built-In Hysterisis to Ensure Jitter Free Operation
Cyclic Operation of MOSFET (Turn-On and Turn-Off)
Under Continuous Fault Condition
D Flexibility to Set MOSFET Turn-Off Temperature
D
D
D
D
D
D
ORDERING INFORMATION: SiDB766761
DESCRIPTION
The Vishay Siliconix SUB60N04-15LT, temperature sensing
MOSFET, provides the capabilities to sense the junction
temperature, TJ, and implement self-protection in a control
circuit. An electrically isolated poly-silicon diode, which is
located in the close proximity to MOSFET junction on the same
die, facilitates temperature sensing. The forward voltage drop
of sense diode has a negative temperature co-efficient of
approximately −2mV/_C. In other words, the forward voltage
drop of the sense diode is inversely proportional to the
MOSFET junction temperature.
This evaluation board demonstrates the self-protection feature in
a control circuit, using SUB60N04-15LT, the temperature sensing
MOSFET. The cyclic turn-off and turn-on of the MOSFET under
the fault condition protects it from catastrophic failure.
The appendix includes, a schematic diagram, test setup,
bill-of-materials, and PCB layouts. Using this information, one
can incorporate the basic control scheme described here, in
any core system design of an application.
The demonstration board layout is available in Gerber file format. Contact your Vishay Siliconix sales representative/ distributor for a copy.
CIRCUIT DESCRIPTION
The schematic diagram shown in Appendix (A) is a simple
comparator circuit that uses a low cost op-amp, LMV321. This
IC is identified as “U1.” The op-amp output Pin 4 provides gate
drive approximately 4.8 V through resistor R6 to the
temperature sensing MOSFET, Q1. The latter in turn controls
the “load” connected between its drain, Pin 3, and +12 V. The
voltage divider, resistors R1 and R2, establishes reference
voltage VREF = 490 mV. 5-V logic level input at the INPUT
terminal provides the bias current, IF = 250 A, for the sense
diode on Pins 2 and 4 of Q1. The op-amp is configured for
non-inverting mode by connecting the sense diode forward
voltage drop to Pin 1, the “+” input through resistors R7. The
feedback resistor R4 establishes 20-mV hysteresis on R7 to
ensure jitter free operation. Resistor R5 facilitates monitoring
of gate drive signal. Resistor RG when connected to the
MOSFET gate via jumper J2, cuts down the MOSFET gate
drive to 2.8 V and shifts the MOSFET operation to linear mode.
The peripheral capacitors C1 through C5 are for power supply
filter and noise suppression.
S
D2PAK-5L
T1
G
1 2 3 4 5
G
D
T1
Document Number: 72800
18-Mar-04
S
D1
D2
T2
D
T2
P-Channel MOSFET
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SiDB766761
Vishay Siliconix
TEST SETUP
(a) Laboratory Equipment
D Connect the jumper J1. This provides 5-V logic level
signal on the INPUT terminal. Observe V(G) = 4.8 V
(approximately) The MOSFET turns on. The current flows
through the load (lighted lamp, if a lamp load is used).
(b) Fault Condition
This configuration facilitates testing with two laboratory power
supplies. Refer to Appendix (B). A 5-V/2-A regulated power
supply between +5 and GND powers up the control circuit. A
separate 12-V/20-A power supply between +12 V and GND
powers the load and MOSFET drain Pin 3 and source Pin 5.
Remove the jumper 3. Thereby, the 5-V logic level power
supply, VLL, for the control circuit is independent of over load
or shorted load on MOSFET side. Diodes D1 and D2 prevent
reverse current flow in case of accidental connection of both
power supplies when the jumper J3 is not removed.
Connect a suitable load that would draw about 1 A, e.g. a lamp
(12 V, 1 A) or a resistor (12 , 25 W) between terminal +12 V
and load.
(b) Field Simulated Testing
Using a 12-V battery can simulate field level testing. This
power source on the load side is capable of supplying
continuous over load/short circuit current. In other words, the
battery will have the capacity to maintain the terminal voltage
of the 12-V even under short circuit conditions. Connect the
battery between +12 V and GND. In this case, a separate 5-V
logic level power supply is not required. The jumper J3 must be
in place. The latter provides the 5-V logic level, VLL, to the
control circuit via on-board voltage regulator LM2937. The IC
is identified as Q2.
D Connect the jumper J4, Which is an external shorting link
(not supplied), to short-circuit the load. Monitor V(G) =
4.8 V, the MOSFET is still in “on” state. Observe
excessive current flow from the 12-V supply. The
MOSFET starts heating up. After sometime, the MOSFET
turns off, monitor V(G) = 0 (< 0.2 V). The load current
drops to zero. The MOSFET starts cooling down. The
MOSFET turns on again when cooling is complete.
Observe V(G) = 4.8 V and the load current flow from the
power supply.
D The cycle repeats as long as jumper J4 is connected
across the +12 V and load terminals and the setup is
powered.
D Removing jumper J4 restores normal operation. The
MOSFET maintains an “on” state with jumper J1 in place,
with 5 V at the INPUT terminal.
ACCELERATED TESTING
Jumper J2 facilitates accelerated testing. Now the actual gate
voltage drops to 2.8 V because of voltage divider formed at the
MOSFET gate Pin 1, by resistors R6 and RG. Refer to the
schematic diagram in Appendix (A). This drives the MOSFET
in linear mode, resulting in accelerated heating of the MOSFET
and faster turn off. The cycle time of fault condition is reduced.
SUMMARY
OPERATION
Either step (a) or step (B) of the Test Setup enables the testing
and demonstration of the self-protection feature as follows:
(a) Normal Operation
D
D
D
D
Remove jumpers J1 and J2.
Power-up the circuit
Connect the Oscilloscope or DMM to monitoring Pin G.
Observe V(G) = 0 (or <0.2 V), MOSFET in “off” state. No
current flow in the load.
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The evaluation board shows implementation of a
self-protecting feature in a control circuit for a high-side
connected floating load, using the temperature sensing
MOSFET, SUB60N04-15LT The circuit operation, under
normal and fault conditions, demonstrates that the MOSFET
can provide the desired load control function and also sustain
continuous fault condition while exhibiting a self-protection
feature. The basic control circuit can be easily incorporated
into the core design of an application using the information
provided in the Appendix.
For additional information on temperature sensing MOSFETs
and actual design example refer to application note AN820
available via the Vishay web site, www.vishay.com.
Document Number: 72800
18-Mar-04
SiDB766761
Vishay Siliconix
APPENDIX A: SCHEMATIC DIAGRAM
J3
Q2
LM2937IMP-5.0
3
C2
1000 F
25 V
C3
0.1 F
25 V
C5
0.1 F
1
JUMPER
Terminal GND
−
U1
1 +
R7
10 k
1%
R3, 18 k
5
3
C1
560 pF
Signal Ground
2
2
D2
1N5819M
C4
0.1 F
25 V
4
2
LMV321M5
1
Screw
LOAD Terminal
Q1
2
1
LIMIT
R2
22 k
1%
J4
Gate
2
J2
1
3
R6, 560 R4, 560 k, 1%
Screw
+12 V Terminal
2
R5, 18 k
490 mV
2
Terminal INPUT
1
1
C6
10 F
R1
200 k
1%
J1
VIN
GND
SUB60N04-15LT
D1
1N5819M
VOUT
3 Terminals
VLL
Terminal +5 V
RG
820 4
5
Power Ground
GND Screw
Terminal
APPENDIX B: TEST SETUP
Jumper J3
To Power The EVB From 12-V Power Supply or Battery
(In The Absence of 5-V Power Supply)
Jumper J4
Load Shorting Link
V(LL) 5 V
Regulated Power Supply
Lamp Load
+
−
−
Jumper J1
To Continuously Input
5-V Signal
Document Number: 72800
18-Mar-04
12-V
Automotive
Battery
or
Power Supply
Jumper J2
To Operate MOSFET
at 2.8 V
Connect to Oscilloscope to
Monitor MOSFET Status
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SiDB766761
Vishay Siliconix
1399 (mil)
APPENDIX C: LAYOUT
2000 (mil)
FIGURE 3. Silk Screen
FIGURE 4. Top Layer
FIGURE 5. Bottom Layer
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Document Number: 72800
18-Mar-04
SiDB766761
Vishay Siliconix
EVALUATION BOARD DISCLAIMER
Vishay Siliconix (Vishay) provides this evaluation board (EVB) under the following conditions:
The EVB is intended for DEMONSTRATION OR ENGINEERING DEVELOPMENT OR EVALUATION PURPOSES ONLY and is
not considered to be fit for commercial use. Vishay assumes no liability for application assistance, customer product design,
infringement of patents, or software performance.
Please read the EVB datasheet carefully; it contains important information for its use. The user assumes all responsibility and
liability for safe and proper handling of the EVB and to take any and all appropriate precautions concerning electrostatic discharge.
Further, the user indemnifies Vishay from all claims arising from handling or use. The EVB is not regulatory-compliant or
agency-certified. Any user handling the product must have electronics training and observe good laboratory practice standards.
THE EVB IS PROVIDED AS IS, WHERE IS, WITH NO WARRANTIES WHATSOEVER, EITHER EXPRESSED, IMPLIED, OR
STATUTORY, AND SPECIFICALLY EXCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR ANY
PARTICULAR PURPOSE.
EXCEPT TO THE EXTENT OF THE INDEMNITY SET FORTH ABOVE, NEITHER PARTY SHALL BE LIABLE TO THE OTHER
FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
The EVB is not provided exclusively to the user and Vishay may supply the EVB to other users. No license is granted under any
patent right or any other intellectual property right of Vishay.
APPENDIX D: BILL-OF-MATERIAL
Item
Qty
Designator
Description
Footprint
Part Number
Manufacturer
1
1
R1
200-k Resistor, 1%
805
CRCW0805, 200 k, 1%
Vishay Dale
2
1
R2
22-k Resistor, 1%
805
CRCW0805, 22 k, 1%
Vishay Dale
3
2
R3, R5
18-k Resistor, 5%
805
CRCW0805, 18 k, 5%
Vishay Dale
4
1
R4
560-k Resistor, 1%
805
CRCW0805, 560 k, 1%
Vishay Dale
5
1
R6
560- Resistor, 5%
805
CRCW0805, 560 , 5%
Vishay Dale
6
1
R7
10-k Resistor, 1%
805
CRCW0805,10 k, 1%
Vishay Dale
7
1
RG
820- Resistor, 5%
805
CRCW0805, 820 , 5%
Vishay Dale
8
1
C1
560-pF/25-V Ceramic Capacitor
805
VJ0805Y561JXAA
Vishay Vitramon
9
1
C2
1000-F/25-V, Electrolytic Capacitor
RB-0.2/0.4
10
3
C3, C4, C5
0.1-F/25-V, Ceramic Capacitor
805
VJ0805Y104JXAA
Vishay Vitramon
11
1
C6
10-F/25-V, Ceramic Capacitor
2512
VJ2225V106MXAA
Vishay Vitramon
12
2
D1, D2
1N5819M, Schottky Diode, 40 V, 1 A, SOD87
MELF
13
1
Q1
SUB60N04-15LT, Temperture Sense MOSFET, 40 V
D2PAK-5L
SUB60N04-15LT
Vishay Siliconix
14
1
Q2
LM2937IMP-5.0, IC, 5 V, 500 mA, LDO VREG
SOT-223
15
1
U1
LMV321M5, IC, Low Voltage Op Amp
SC70-5
16
3
J1, J2, J3
Jumper Pins
SIP-2
929834-02-36-ND
Digi-Key
17
3
JMP Shunt
Jumper Shunts
A26228-ND
Digi-Key
18
2
+5 V, GND
In Board Pins
TURRET
V1055-ND
Digi-Key
19
2
IN, G
Press-In Terminal
TURRET
V1073-ND
Digi-Key
20
3
+12 V. Load, GND
Terminal, 12-V, GND
LOADCON
7693-ND
Digi-Key
21
1
PCB
Evaluation PC Board
TSM1
Vishay Siliconix
Document Number: 72800
18-Mar-04
www.vishay.com
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