UC3842A/3843A

LINEAR INTEGRATED CIRCUIT

UNISONICTECHNOLOGIESCO.,LTD

5 of 9

www.unisonic.com.tw

QW-R103-002,D

OPEN-LOOP LABORATORY TEST FIXTURE

1

2

8

7

3

6

4

5

A

Vcc

1k

Ω

/ 1W

CT

RT

5k

Ω

Error

Amp

Adjust

OUTPUT

High peak current associated with capacity loads necessitate careful grounding techniques. Timing and bypass

capacitors should be connected close to pin 5 in single point GND. The transistor and 5k

Ω potentio-meter are used

to sample the oscillator waveform and apply an adjustable Ramp to Pin 3.

UNDER-VOLTAGE LOCKOUT

7

Vcc

Von=16V

Voff=10V

ON/OFF Command

to rest of IC

Von

Voff

<1mA

<15mA

Icc

Vcc

During Under-Voltage Lockout, the output driver is biased to a high impedance state. Pin 6 should be shunt to

GND with a bleeder resistor to prevent activating the power switch with output leakage currents.

ERROR AMPLIFIER CONFIGURATION

2

1

0.5mA

2.5V

Zf

Zi

Error amplifier can source or sink up to 0.5mA