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 vari-
able. Current limitation takes place for a voltage drop of
In the event of voltages of approx. V
ternal FET is switched off and the latch for short-circuit
detection is reset.
< 5.0 V, the ex-
Batt
V
V
100 mV.
Owing
to
the
difference
T1
A hysteresis ensures that the FET is switched on again at
–V
10 mV, current limitation occurs only when
T1
T2
approximately V
5.4 V.
Batt
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 ca-
pacitor 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.
Overvoltage Detection
Stage 1
If overvoltages V
> 20 V (typ.) occur, the external
Batt
transistor is switched off and switched on again at
< 18.5 V (hysteresis).
V
Batt
Stage 2
Pins 13 and 14, Charge Pump and Output
If V
> 28.5 V (typ.), the voltage limitation of the IC
Batt
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
Output, Pin 14, is suitable for controlling a power MOS-
FET. During the active integration phase, the supply
current of the operational amplifier is mainly supplied by
the capacitor C (bootstrapping). Additionally, a trickle
3
V
Batt
< 23 V, the overvoltage detection stage 2 is
charge is generated by an integrated oscillator
switched off.
(f
400 kHz) and a voltage doubler circuit. This per-
13
mits a gate voltage supply at a duty cycle of 100%.
Absolute Maximum Ratings
Parameters
Junction temperature
Symbol
Value
150
Unit
°C
T
j
Ambient temperature range
Storage temperature range
T
–40 to +110
–55 to +125
°C
amb
T
°C
stg
Thermal Resistance
Parameters
Symbol
Value
120
Unit
K/W
Junction ambient
R
thJA
Electrical Characteristics
T
amb
= –40 to +110°C, V
= 9 to 16.5 V, (basic function is guaranteed between 6.0 V to 9.0 V) reference point ground,
Batt
unless otherwise specified (see figure 1). All other values refer to Pin GND (Pin 1).
Parameters
Current consumption
Supply voltage
Test Conditions / Pins
Pin 16
Overvoltage detection,
stage 1
Symbol
Min.
Typ.
Max.
6.8
25
Unit
mA
V
I
S
V
Batt
Stabilized voltage
Battery undervoltage
detection
I = 10 mA
– on
– off
Pin 16
V
24.5
4.4
4.8
27.0
5.6
6.0
V
V
S
S
V
Batt
5.0
5.4
4 (8)
TELEFUNKEN Semiconductors
Rev. A1, 14-Feb-97
TEMIC [ TEMIC SEMICONDUCTORS ]
