HI-SINCERITY

MICROELECTRONICS CORP.

Spec. No. : HP200202

Issued Date : 1998.08.01

Revised Date : 2002.12.03

Page No. : 6/10

H3842P

HSMC Product Specification

Application Information

Open Loop Test Circuit

Oscillator and Output Waveforms

Error Amp Configuration

Under Voltage Lockout

RT

CT

4

5

6

7

8

5V REG

PWM

Clock

Oscillator

Id

Output

GND

CT

Output

Large RT / Small CT

CT

Output

Small RT / Large CT

Vcc

1

2

3

4.7KΩ

1KΩ

4.7KΩ

5KΩ

100KΩ

RT

0.1uF

0.1uF

CT

1W

1KΩ

Error Amp.

Adjust

I

Adjust

HPN2222A

COMP

RT/CT

V

Vcc

Output

Ground

Ground

Output

Vcc

Vref

1

2

3

4

5

6

7

8

REF

SENSE

A

H3842

High peak currents associated with capacitive loads necessitate careful grounding techniques. Timing and

bypass capacitors should be connected close to pin5 in a single point ground. The transistor and 5KΩ

potentiometerare used to samplethe oscillator waveform and apply an adjustable ramp to pin3.

Zi

Zf

V

COMP

2.5V

1mA

1

2

FB

+

-

ON/OFF Command

Von

Voff

H3842

To Rest Of IC

16V

10V

Icc

<17mA

<0.5mA

Vcc

Voff Von

Vi

7