CIRCUIT DESCRIPTION

The TDA8139 is a dual voltage regulator with Reset

and Disable.

The two regulation parts are supplied from one

voltage reference circuit trimmed by zener zap

during EWS test. Since the supply voltage of this

not work if the Pin 1 is not supplied.

The outputs stages have been realized in dar-

lington configuration with a drop typical of 1.2V.

The disable circuit, switch-off the output 2 if a

voltage lower than 0.8V is applied at pin 4.

The Reset circuit checks the voltage at the output

the comparator "a" (see Figure 1) discharges rap-

idly the capacitor Ce and the reset output goes at

once low. When the voltage at the OUT 1 rises

increases linearly to 2.5V corresponding to a delay

=

Ce

10

µA

(see figure 2),

then the reset output goes high again. To avoid

glitches in the reset output, the second comparator

"b" has a large hysteresis (1.9V).

63

9

8

4

5

2

1

RESET

V

IN2

V

O2

Ce

0.1

µF

C1

C2

C3

C4

DISABLE

C1 to C4 = 10

µF

7

R1

R2

TDA8139

typ. val R1 = 2.2

Ω

TYPICAL APPLICATION

TDA8139

4/5