AMC3842B 데이터 시트보기 (PDF) - Unspecified

부품명

상세내역

제조사

AMC3842B

CURRENT MODE PWM CONTROLLER

Unspecified 

AMC DOC. #: AMC3842B_C (LF)

March 2004

AMC3842B/43B

CURRENT MODE PWM CONTROLLER

Application Information

Error

Amp

Rf

RS

COMP

ISENSE

Cf GND

2R

R

1V

Current

Sense

Comparator

Fig. 1. Current Sense Circuit

Peak current (IS) is set by: IS(MAX) = 1V/RS

2.5V

Error

Amp

0.5mA

Zi

VFB

Zf COMP

VREF

RT

RT/CT

CT

GND

Fig. 2. Error Amplifier Configuration - the

amplifier can source or sink up to 0.5mA

Fig. 3. Oscillator Section

1.72

For RT < 5K, f = RTCT

VREF

RT

4.7K

1K

Error AMP

Adjust

4.7K

2N2222

100K

5K

ISENSE

Adjust

COMP VREF

VFB

VCC

ISENSE Output

RT/CT GND

CT

0.1µF

1K,

1W

0.1µF

VCC

Output

GND

Fig. 4. Open-loop laboratory test fixture: Careful grounding techniques are necessary for high peak

currents associated with capacitive loads. Timing and bypass capacitors should be connected to GND pin

in a single point ground. The transistor and 5K potentiometer are used to sample the oscillator waveform

and apply an adjustable ramp to the ISENSE pin

Copyright © 2002, ADD Microtech Corp.

6

www.addmtek.com

Share Link: