U842B データシートの表示（PDF） - Temic Semiconductors

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U842B

Wiper Control for Intermittent and Wipe/ Wash Mode

Temic Semiconductors 

U842B

Block Diagram

VS

GND

6

7

1

INT

1/2 VS

21 V

+

–

25 pF 21 V

+

2

WASH

–

Stabilization

POR

Load–dump –

detection

Logic

28 V

8

OUT

250 mV

+

–

0.5 Ω

25 pF 21 V

+

3

PARK

–

Oscillator

25 pF 21 V

VS

+

–

25 pF 21 V

4

PAUS

Upper

switching

point

OUT

21 V

5

OSC

13287

Figure 2. Block diagram

Basic Circuit

Power Supply

For reasons of interference protection and surge immu-

nity, a RC circuitry has to be provided to limit the current,

and to supply the integrated circuit in the case of supply

voltage drops.

Suggested values: R1 = 180 W, C1 = 47 mF,

(see figure 2)

The supply (Pin 6) is clamped with a 21-V Zener diode.

The operation voltage ranges between VBatt = 9 V to 16 V.

The capacitor, C1, can be dimensioned smaller (typically:

10 mF) if a diode is used in the supply against polarity re-

versal. In this case of negative interference pulses, there,

is only a small discharge current of the circuit.

Oscillator

All timing sequences in the circuit are derived from an RC

oscillator which is charged by an external resistor, R9, and

discharged by an integrated 2-k W resistor. The basic

frequency, f0, is determined by the capacitor, C2, and an

integrated voltage divider. The basic frequency is

adjusted to 320 Hz ( 3.125 ms ) by C2 = 100 nF and

R9 = 220 kW.

The tolerances and the temperature coefficients of the ex-

ternal components determine the precision of the

oscillator frequency. A 1% metallic-film resistor and a

5% capacitor are recommended..

The debouncing times of the inputs, the turn-on time of

the relay (t5), the pre-wash delay (t1), the dry wiping time

(t2) and the debouncing time (t7, short circuit detection)

depend on the oscillator frequency (f0) as follows:

2 (12)

TELEFUNKEN Semiconductors

Rev. A2, 03-Feb-97

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