4

4810B–AUTO–10/05

U6433B

3.

Functional Description

3.1

Pin 1, GND

The integrated circuit is protected against damage via resistor R

battery reversal.

An integrated protection circuit together with external resistances R

pulses in the IC.

3.2

Pin 2, Supply Voltage, V

The arrangement of the supply connections to pin 2 must be so as to ensure that, on the con-

nection printed circuit board (PCB), the resistance of V

3.3

Pin 3, Relay Control Output (Driver)

The relay control output is a high-side driver with a low saturation voltage and is capable of driv-

ing a typical automotive relay with a minimum coil resistance of 60

Ω.

3.4

Pins 4 and 5, Oscillator

The flashing frequency, f

page 2):

where

C

R

In the case of a lamp outage (see pin 7) the oscillator frequency is switched to the lamp outage

frequency f

2.2

× f

Duty cycle in normal flashing mode: 50%

Duty cycle in lamp outage mode: 40% (bright phase)

3.5

Pin 6, Supply Voltage, Sense

For accurate monitoring via the shunt resistor, a minimized layer resistance from point V

to pin 6 is recommended.

3.6

Pin 7, Lamp Outage Detection

3.6.1

Control Signal Threshold 1 (49-mV Comparator K1)

The detection point for lamp failure can be calculated from the control signal threshold, typically

49 mV with V

reached at a lamp load of 21W + 11.4W. The variation of the control signal threshold supply volt-

age takes into account the PTC characteristic of filament lamps.

f

1

1

R

1

C

1

×

1.5

×

-------------------------------------Hz

≈