AMC3842B Datasheet, PDF (7/11 Pages) List of Unclassifed Manufacturers – CURRENT MODE PWM CONTROLLER

AMC3842B/43B/44B/45B
APPLICATION INFORMATION
Error
Amp
R_f
R_S
COMP
I_SENSE
C_{f GND}
2R
R
1V
Current
Sense
Comparator
Fig. 1. Current Sense Circuit
Peak current (I_S) is set by: I_S(MAX) = 1V/R_S
2.5V
Error
Amp
0.5mA
Z_i
V_FB
Z_f ^COMP
V_REF
R_T
R_T/C_T
C_T
GND
Fig. 2. Error Amplifier Configuration - the
amplifier can source or sink up to 0.5mA
Fig. 3. Oscillator Section
1.72
For R_T < 5K, f = _RTCT
V_REF
R_T
4.7K
1K
Error AMP
Adjust
4.7K
2N2222
100K
5K
I_SENSE
Adjust
COMP ^VREF
V_FB
V_CC
I_{SENSE Output}
R_T/C_T GND
0.1µF
1K,
1W
0.1µF
V_CC
Output
GND
Fig.
4. Open-loop laboratory
associated with capacitive
test fixture:
loads. Timing
aCnadrebfyup^ClagTsrsocuanpdaincigtoterschshnoiquuldesbaereconnenceecstseadrytofoGr NhiDghppineaink
currents
a single
point ground. The transistor and 5K potentiometer are used to sample the oscillator waveform and apply an
adjustable ramp to the I_SENSE pin
Copyright © 2006 ADDtek Corp.
7
DD019_F -- OCTOBER 2006