U243B

TELEFUNKEN Semiconductors

Rev. A1, 05-Sep-96

Preliminary Information

4 (6)

D Istable multivibrator

The figure shows the minimum of circuitry necessary for

the operation as an instable multivibrator. The circuit is

suitable for frequencies between 0.05 Hz and approxi-

mately 10 kHz. The frequency can be calculated by using

ing resistor of 3.8 k

W is integrated into the circuit between

pins 8 and 6. This means that, for a load on pin 3 of, for

example, 500

W (open circuits) and zero current, a voltage

of about 1.4 V remains on the load (for 70

WWthe

3.3 k

W on pin 3 ensures correct operation of the instable

multivibrator. The relationship between the on- and off-

periods can be changed in this circuit by inserting a

lines in the figure), e.g., to reduce the “bright”-time.

Figure 2. Flashing generator with small loads

Figure 3. Instable multivibrator for general-purpose applications

Pin Description

Pin

Function

1

IC ground

2

3

Relay driver

4

Pin

Function

5

6

7

Lamp-failure detection

8

Start input (49a)