U6083B_05 ATMEL [ATMEL Corporation], U6083B_05 Datasheet - Page 4

• Manufacturer Part Number: U6083B_05
• Description: PWM Power Control IC with Interference Suppression
• Manufacturer: ATMEL [ATMEL Corporation]

3. Functional Description
3.1
3.1.1
3.1.1.1
3.1.1.2
3.1.2
3.2
3.2.1
3.3
4
Pin 1, Supply Voltage, V
Pin 2, GND
Pin 3, Control Input
U6083B
Overvoltage Detection
Undervoltage Detection
Ground-wire Breakage
Stage 1
Stage 2
If overvoltages of V
switched on again at V
If V
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 (e.g., load dump). The short-
circuit protection is not in operation. At V
stage 2 is switched off. Thus, during overvoltage detection stage 2, the lamp voltage V
culated as follows:
V
V
V
In the event of voltages of approximately V
latch for short-circuit detection is reset.
A hysteresis ensures that the FET is switched on again at approximately V
To protect the FET in the case of ground-wire breakage, a 1 M resistor between gate and
source is recommended to provide proper switch-off conditions.
The pulse width is controlled by means of an external potentiometer (47 k ). The characteristic
(angle of rotation/duty cycle) is linear. The duty cycle can be varied from 18 to 100%. It is possi-
ble to further restrict the duty cycle with the resistors R
In order to reduce the power dissipation of the FET and to increase the lifetime of the lamps, the
IC automatically reduces the maximum duty cycle at pin 8 if the supply voltage exceeds
V
Lamp
S
GS
2
= 13V. Pin 3 is protected against short-circuit to V
= supply voltage of the IC at overvoltage detection stage 2
Batt
= gate - source voltage of the FET
= V
> 28.5V (typically), the voltage limitation of the IC is reduced from V
Batt
S
– V
or V
S
– V
Batt
Batt
GS
Batt
> 20V (typically) occur, the external transistor is switched off, and
< 18.5V (hysteresis).
Batt
Batt
approximately < 23V, the overvoltage detection
< 5.0V, the external FET is switched off and the
Batt
1
and R
and ground (V
2
(see
Figure 7-1 on page
Batt
Batt
S
16.5V).
= 26V to 20V. The
5.4V.
4770B–AUTO–09/05
lamp
11).
is cal-