U6037B

The U6037B has the following features including Low supply current;Integrated relay driver with protection diode;All time periods determined by RC oscillator;Debounced input for ignition key (K1 15);Door switch with adjustable contact current;Delaytriggering by closing the door;Interior lighf is extinguished when ignition is switched on;Delay time: 1 s...20 s;Protection according to VDE 0839;Load dump protection.

The circuit U6037B (DIP 8) from  TELEFUNKEN  electronic  were designed as interior light timers for motorvehicles with an adjustable delay time (1s...20 s). The U6037B is a maskversion of the U6047B family.If a door is opened, the interior lighting is switched on by means of the relay. When the door is closed,the delay time tv is triggered. After expiry of the delay time, the interior light goes out. The delay time can be reset by switching on the ignition.The advantage of this automobile-specific timer comparedwith "standard timers" isthatlongtimes can be realizedwith small capacitances becauseall time sequences are determined byan RC oscillator and  a  frequency  divider.  The  input  IGN  is debounced, the relay driver is integrated and, with the corresponding external circuitry, the circuit is resistant to load dump and interferencevoltages in accordance with DIN 40839.

All timing sequences of U6037B are derived from an RG oscillator whose charge time t1 is determined by an external resistor Rosc and whose discharge time t2 is determined by an integrated 500 resistor,refer to Fig. 2 and 3. Since the temperature response and current of the integrated resistor are considerably greater than those of the external resistor, t1 must be considerably larger than t2 so that the influence of the integrated resistor on the stability  of  the  oscillator  frequency of U6037B  can  be disregarded.For reasons of interference protection and surge immunity, all circuits of U6037B must be provided with an RC circuit for current limitation  in the event of overvoltages and for buffering in the event of voltage dips at Vs.