TEMIC U6084B

U6084B
PWM Power Control with Automatic Duty Cycle Reduction
Description
The U6084B is a bipolar technology PWM-IC designed
for the control of an N-channel power MOSFET used as
a high-side switch. The IC is ideal for use in the brightness
control (dimming) of lamps such as, in dashboard
applications. For a constant brightness the preselected
duty cycle can be reduced automatically as a function of
the supply voltage.
Features
D Interference and damage protection according to
D Pulse width modulation up to 2 kHz clock frequency
D Protection against short circuit, load-dump
VDE 0839 and ISO/TR 7637/1.
overvoltage and reverse VS
D Charge pump noise suppressed
D Duty cycle 0 to 100 % continuously
D Output stage for power MOSFET
D Ground wire breakage protection
Ordering Information
Extended Type Number
U6084B–FP
Package
SO16
Remarks
Block Diagram
VBatt
C5
VS
16
Rsh
11
9
Short circuit
latch monitoring
Current monitoring
+ short circuit detection
12
5
6
C1
Charge
pump
RC oscillator
C3
47 nF
PWM
Logic
47 kW
3
C2
13
Control input
Duty cycle
range
0–100%
Output
Duty cycle
reduction
Voltage
monitoring
4
1
14
Enable/
disable
2
95 9751
C6
150W
R3
Ground
Figure 1. Block diagram with external circuit
TELEFUNKEN Semiconductors
Rev. A1, 14-Feb-97
1 (8)
U6084B
Pin Description
GND
1
16
VS
En / Dis
2
15
NC
VI
3
14
Output
Reduct
4
13
2 VS
Attenuation 5
12
Sense
Osc
6
11
Delay
NC
7
10
NC
NC
8
9
Latch
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Symbol
GND
En / Dis
VI
Reduct
NC
Osc
NC
NC
Latch
NC
Delay
Sense
2VS
Output
NC
VS
Function
IC ground
Enable/disable
Control input (duty cycle)
Duty cycle reduction
Attenuation
Oscillator
Not connected
Not connected
Status short circuit latch
Not connected
Short circuit protection delay
Current sensing
Voltage doubler
Output
Not connected
Supply voltage VS
95 9754
Functional Description
Pin 4, Duty Cycle Reduction
With Pin 4 connected according to figure 2, the set duty
12.5 V. This causes a
cycle is reduced as from VBatt
power reduction in the FET and in the lamps. In addition,
the brightness of the lamps is largely independent of the
supply voltage range, VBatt = 12.5 to 16 V.
Pin1, GND
Ground-Wire Breakage
To protect the FET in the case of ground-wire breakage,
a 820 kW resistor between gate and source it is recommended to provide proper switch-off conditions.
Pin 2, Enable/Disable
The dimmer can be switched on or off with pin 2 independently of the set duty cycle.
Output Slope Control
The rise and fall time (tr, tf) of the lamp voltage can be
limited to reduce radio interference. This is done with an
integrator which controls a power MOSFET as source follower. The slope time is controlled by an external
capacitor C4 and the oscillator current (see figure 2).
Calculation:
tf
+ t +V
Pin 3, Control Input
tf
+ t + 12 V
The pulse width is controlled by means of an external potentiometer (47 kW). The characteristic (angle of
rotation/duty cycle) is linear. The duty cycle can be varied
from 0 to 100%. It is possible to further restrict the duty
cycle with the resistors R1 and R2 (see figure 2).
Pin 3 is protected against short-circuit to VBatt and ground
GND (VBatt 16.5 V).
Pin 5, Attenuation
V2
Approx. >0.7 V or open
< 0.7 V or connected to Pin 1
x
2 (8)
Function
Disable
Enable
C4
I osc
With VBatt = 12 V, C4 = 470 pF and Iosc = 40 m A,we thus
obtain a controlled slope of
r
r
Batt
470 pF
40 mA
+ 141
m
s
Capacitor C4 connected to Pin 5 damps oscillation
tendencies.
Pin 6, Oscillator
The oscillator determines the frequency of the output
voltage. This is defined by an external capacitor, C2. It is
TELEFUNKEN Semiconductors
Rev. A1, 14-Feb-97
U6084B
charged with a constant current, I, until the upper switching threshold is reached. A second current source is then
activated which taps a double current, 2 I, from the
charging current. The capacitor, C2, is thus discharged by
the current, I, until the lower switching threshold is
reached. The second source is then switched off again and
the procedure starts once more.
A selection of different values of C2 and C4, provides a
range of oscillator frequency, f, from 10 to 2000 Hz.
Pins 7, 8, 10 and 15
Not connected.
Example for Oscillator Frequency Calculation
+V
V¦ + V
V + V
V T100
T 100
TL
S
+ (V * I
a + (V * I
a + (V * I
a
S
S
1
Batt
2
Batt
3
Batt
a
R 3)
S
a
R 3)
S
a
R 3)
S
Pin 9, Status Short Circuit Latch
1
2
3
The status of the short-circuit latch can be monitored via
Pin 9 (open collector output).
where
V T100
+ High switching threshold (100% duty cycle)
V Tt100
V TL
Pin 9
L
H
+ High switching threshold (t 100% duty cycle)
+ Low switching threshold
Function
Short-circuit detected
No short-circuit detected
a1, a2 and a3 are fixed constant.
Pins 11 and 12, Short-Circuit Protection
and Current Sensing
The above mentioned threshold voltages are calculated
for the following values given in the data sheet.
1. Short-Circuit Detection and Time Delay, td
VBatt = 12 V, IS = 4 mA, R3 = 150 W ,
a1 = 0.7, a2 = 0.67 and a3 = 0.28.
+
* 4 mA 150 W
V t + 11.4 V 0.67 + 7.6 V
V + 11.4 V 0.28 + 3.2 V
V T100
)
(12 V
0.7
[8 V
T 100
TL
For a duty cycle of 100%, an oscillator frequency, f, is
as follows:
f
+2
I osc
(V T100
Therefore:
f
+2
*V
)
TL
C2
+
* 3.2 V)
Time delay, td, is as follows:
40 mA
(8 V
+
, where C 2
22 nF
40 mA
and I osc
The lamp current is monitored by means of an external
shunt resistor. If the lamp current exceeds the threshold
for the short-circuit detection circuit (VT2 90 mV), the
duty cycle is switched over to 100% and the capacitor C5
is charged by a current source of 20 m A (Ich – Idis). The
external FET is switched off after the cut-off threshold
(VT11) is reached. Renewed switching on the FET is possible only after a power-on reset. The current source, Idis,
ensures that the capacitor C5 is not charged by parasitic
currents. The capacitor C5 is discharged by Idis to typ.
0.7 V.
22 nF
+ 189 Hz
td
+ C @ (V * 0.7 V)ń(I * I
5
T11
ch
dis
)
For a duty cycle of less than 100%, the oscillator frequency, f, is as follows:
f
+2
(V Tt100
whereas
*V
TL)
C4 = 470 pF
+ 2 ǒ7.6 V * 3.2 VǓ
+ 185 Hz
I osc
C2
m
)4
40 A
22 nF
With C5 = 330 nF and VBatt = 12 V, we have
V Batt
C4
td
)4
TELEFUNKEN Semiconductors
Rev. A1, 14-Feb-97
12 V
470 pF
+ 330 nF @ (9.8 V * 0.7 V)ń20 mA
+ 150 ms.
3 (8)
U6084B
2. Current Limitation
Pin 16, Supply Voltage, Vs or VBatt
Undervoltage Detection:
The lamp current is limited by a control amplifier that
protects the external power transistor. The voltage drop
across an external shunt resistor acts as the measured variable. Current limitation takes place for a voltage drop of
Owing
to
the
difference
VT1 100 mV.
VT1–VT2 10 mV, current limitation occurs only when
the short-circuit detection circuit has responded.
After a power-on reset, the output is inactive for half an
oscillator cycle. During this time , the supply voltage capacitor can be charged so that current limitation is
guaranteed in the event of a short circuit when the IC is
switched on for the first time.
In the event of voltages of approx. VBatt < 5.0 V, the external FET is switched off and the latch for short-circuit
detection is reset.
A hysteresis ensures that the FET is switched on again at
approximately VBatt 5.4 V.
Overvoltage Detection
Stage 1
If overvoltages VBatt > 20 V (typ.) occur, the external
transistor is switched off and switched on again at
VBatt < 18.5 V (hysteresis).
Stage 2
Pins 13 and 14, Charge Pump and Output
Output, Pin 14, is suitable for controlling a power MOSFET. During the active integration phase, the supply
current of the operational amplifier is mainly supplied by
the capacitor C3 (bootstrapping). Additionally, a trickle
charge is generated by an integrated oscillator
(f13 400 kHz) and a voltage doubler circuit. This permits a gate voltage supply at a duty cycle of 100%.
If VBatt > 28.5 V (typ.), the voltage limitation of the IC
is reduced from 26 V to 20 V. The gate of the external
transistor remains at the potential of the IC ground, thus
producing voltage sharing between FET and lamps in the
event of overvoltage pulses occuring (e.g., load-dump).
The short-circuit protection is not in operation. At
VBatt < 23 V, the overvoltage detection stage 2 is
switched off.
Absolute Maximum Ratings
Parameters
Junction temperature
Ambient temperature range
Storage temperature range
Symbol
Tj
Tamb
Tstg
Value
150
–40 to +110
–55 to +125
Unit
°C
°C
°C
Symbol
RthJA
Value
120
Unit
K/W
Thermal Resistance
Parameters
Junction ambient
Electrical Characteristics
Tamb = –40 to +110°C, VBatt = 9 to 16.5 V, (basic function is guaranteed between 6.0 V to 9.0 V) reference point ground,
unless otherwise specified (see figure 1). All other values refer to Pin GND (Pin 1).
Parameters
Current consumption
Supply voltage
Stabilized voltage
Battery undervoltage
detection
4 (8)
Test Conditions / Pins
Pin 16
Overvoltage detection,
stage 1
IS = 10 mA
Pin 16
– on
– off
Symbol
IS
VBatt
Min.
Typ.
VS
VBatt
24.5
4.4
4.8
5.0
5.4
Max.
6.8
25
Unit
mA
V
27.0
5.6
6.0
V
V
TELEFUNKEN Semiconductors
Rev. A1, 14-Feb-97
U6084B
Parameters
Test Conditions / Pins
Battery overvoltage detection
Pin 2
Stage 1:
– on
– off
Stage 2:
– on
– off
Stabilized voltage
IS = 30 mA
Pin 16
Short-circuit protection
Pin 12
Short-circuit current limita- VT1 = VS – V12
tion
Short-circuit detection
VT2 = VS – V12
Symbol
Min.
Typ.
Max.
Unit
VBatt
20.0
18.5
28.5
23.0
20.0
21.7
20.3
32.5
26.5
21.5
V
VZ
18.3
16.7
25.5
19.5
18.5
VT1
85
100
120
mV
VT2
75
3
90
10
105
30
mV
mV
9.5
9.8
23
3
20
10.1
27
mA
150
350
mV
VBatt
VT1 – VT2
Delay timer short circuit detection
Pin 11
Switched off threshold
VT11 = VS – V11
Charge current
Dicharge current
Capacitance current
I5 = Ich – Idis
Output short-circuit latch
Pin 9
Saturation voltage
I9 = 100 mA
Voltage doubler
Pin 13
Voltage
Duty cycle 100%
Oscillator frequency
Internal voltage
I13 = 5 mA
g limitation
(whichever is lower)
Gate output
Pin 14
Voltage
g
Low level
VBatt = 16.5 V,
Tamb = 110 °C, R3 = 150 W
High level,
duty cycle 100%
Current
V14 = Low level
VT11
Ich
Idis
I5
Vsat
400
27.5
(VS+15)
520
30.0
(VS+16)
kHz
V
V14
0.35
0.70
0.95
1.5 *)
V
V14
V 14
Lower
Oscillator current
Frequency tolerance
*)
V13
I14
1.0
–1.0
mA
I2
–20
–40
–60
mA
V4
6.9
7.4
8.0
V
f
a1
10
0.68
Hz
0.7
2000
0.72
a2
0.65
0.67
0.69
a3
0.26
0.28
0.3
26
6.0
40
9.9
54
13.5
Pin 4
I4 = 500 mA
V 14
a
+ High, a +
+ Low, a +
+ VV
1
2
Pin6
V T100
VS
V Tt100
VS
TL
3
V
mA
mA
2 VS
280
26
(VS+14)
Pin 2
V2 = 0 V
V
V13
f13
V13
V13
V14 = High level, I13 > | I14 |
Enable/ Disable
Current
Duty cycle reduction
Z-voltage
Oscillator
Frequency
Threshold cycle
Upper
13
V
S
VBatt = 12 V
C4 open, C2 = 470 nF,
duty cycle = 50%
Iosc
f
mA
Hz
Reference point is battery ground.
TELEFUNKEN Semiconductors
Rev. A1, 14-Feb-97
5 (8)
6 (8)
95 9757
22 nF
47 m F
C1
R2
C2
C6
47 kW
R1
I
30 k W
VS
VS
4
3
6
100 W
5
Reset
Low voltage
monitoring
+
–
+
–
Reset
Switch – on
delay
Overvoltage
monitoring
stage 1
2I
Oscillator
VS
VS
2
Reset
–
+
VS
VS
C5
Idis
11
150 W
Ich
VS
330 nF
VS
9
Ground
R3
1
+
8
NC
7
NC
15
14
13
12
10 mV
90 mV
VS
VS
Voltage
doubler
10
NC
–
Current limiting
NC
Overvoltage
monitoring
stage 2
16
820 kW
C4
47 pF
47 nF
Load
RL
C3
Rsh
VBatt
U6084B
Application
Figure 2.
TELEFUNKEN Semiconductors
Rev. A1, 14-Feb-97
U6084B
Dimensions in mm
Package SO16
Dimensions in mm
5.2
4.8
10.0
9.85
3.7
1.4
0.25
0.10
0.4
1.27
6.15
5.85
8.89
16
0.2
3.8
9
technical drawings
according to DIN
specifications
1
TELEFUNKEN Semiconductors
Rev. A1, 14-Feb-97
13036
8
7 (8)
U6084B
Ozone Depleting Substances Policy Statement
It is the policy of TEMIC TELEFUNKEN microelectronic GmbH to
1. Meet all present and future national and international statutory requirements.
2. Regularly and continuously improve the performance of our products, processes, distribution and operating systems
with respect to their impact on the health and safety of our employees and the public, as well as their impact on
the environment.
It is particular concern to control or eliminate releases of those substances into the atmosphere which are known as
ozone depleting substances ( ODSs).
The Montreal Protocol ( 1987) and its London Amendments ( 1990) intend to severely restrict the use of ODSs and
forbid their use within the next ten years. Various national and international initiatives are pressing for an earlier ban
on these substances.
TEMIC TELEFUNKEN microelectronic GmbH semiconductor division has been able to use its policy of
continuous improvements to eliminate the use of ODSs listed in the following documents.
1. Annex A, B and list of transitional substances of the Montreal Protocol and the London Amendments respectively
2 . Class I and II ozone depleting substances in the Clean Air Act Amendments of 1990 by the Environmental
Protection Agency ( EPA) in the USA
3. Council Decision 88/540/EEC and 91/690/EEC Annex A, B and C ( transitional substances ) respectively.
TEMIC can certify that our semiconductors are not manufactured with ozone depleting substances and do not contain
such substances.
We reserve the right to make changes to improve technical design and may do so without further notice.
Parameters can vary in different applications. All operating parameters must be validated for each customer
application by the customer. Should the buyer use TEMIC products for any unintended or unauthorized
application, the buyer shall indemnify TEMIC against all claims, costs, damages, and expenses, arising out of,
directly or indirectly, any claim of personal damage, injury or death associated with such unintended or
unauthorized use.
TEMIC TELEFUNKEN microelectronic GmbH, P.O.B. 3535, D-74025 Heilbronn, Germany
Telephone: 49 ( 0 ) 7131 67 2831, Fax number: 49 ( 0 ) 7131 67 2423
8 (8)
TELEFUNKEN Semiconductors
Rev. A1, 14-Feb-97