U6049B

TELEFUNKEN Semiconductors

Rev. A3, 04-Feb-97

3 (8)

Oscillator, Pin 6

Oscillator frequency, f, is determined mainly by

whereas the integrated resistance (2 k

W) is responsible

for discharge time. For the stability of the oscillator

than internal resistance (2 k

W), because the temperature

response and the tolerances of the integrated resistance

are considerably greater than the external resistance

value.

Oscillator frequency, f, is calculated as follows:

f

+

1

t

1

) t

2

where

oscillator frequency, f, as follows:

t

3

+ 6

1

f

t

d

+ 73728

1

f

frequencies from 1 Hz to 20 kHz.

Output, Pin 2

Output Pin 2 is an open-collector Darlington circuit with

integrated 23-V Z-diode for limitation of the inductive

cut–off pulse of the relay coil. The maximum static

collector current must not exceed 300 mA and the satura-

tion voltage is typically 1.1 V @ 200 mA.

Interference Voltages and Load-Dump

Z-diode, while the inputs are protected by a series resistor,

integrated Z-diode and RF-capacitor.

The relay control output is protected via the integrated

23-V Z-diode in the case of short interference peaks. It is

switched to conductive condition for a battery voltage of

greater than approx. 40 V in the case of load-dump. The

output transistor is dimensioned so that it can withstand

the current produced.

Power-on Reset

When the operating voltage is switched on, an internal

power-on reset pulse (POR) is generated which sets the

logic of the circuits to a defined initial condition. The

relay control output is disabled.

7 V

15 pF

20 k

W

–

+

2 V

Pin 3

20 k

W

94 8813

100 nF

Ignition

Terminal 15

Figure 5. Input circuit for ignition (Pin 3)

7 V

15 pF

–

+

Pin 4, 5

94 8815

Figure 6. Input circuit Pin 4 and Pin 5

Relay Control Output behavior, Pin 2

The U6049B controls the cooling fan motor in an automo-

bile by means of a relay.

Figure 5 shows the internal input circuit of ignition

(Pin 3). It has an integrated pull-down resistor (20 k

W),

RF-capacitor (15 pF) and 7-V Z-diode. It reacts to volt-

ages greater than 2 V.

For the programming input, Pin 5, and thermal switch

input, Pin 4, there is neither a pull-up nor pull-down resis-

tor integrated internally (see figure 6).

One can reduce the standby current through the internal

Ignition input (terminal 15) is not debounced. De-

connected to Pin 3 (see figures 1 and 7).