PRELIMINARY
AIC3842
Current-Mode PWM Controller
Analog Integrations Corporation 4F, 9, Industry E. 9th Rd, Science Based Industrial Park, Hsinchu Taiwan, ROC www.analog.com.tw
DS-3842-P1 May 5, 00 TEL: 886-3-5772500 FAX: 886-3-5772510 1
n FEATURES
l Low Start-Up Current (300µA Typical)
l Internal Precision Reference.
l 500KHz Current-Mode Operation.
l Pulse-by-Pulse Current Limiting.
l Automatic Feed-Forward Compensation.
l Optimized for Off-Line and DC/DC Converters.
l Undervoltage Lockout with Hysteresis.
l Double Pulse Suppression.
l High Current Totem-Pole Output.
n APPLICATIONS
l Off-Line Converter.
l DC/DC Converter.
n DESCRIPTION
The AIC3842 control IC provides the features
that are necessary to implement off-line or
DC/DC Converter fixed-frequency current-mode
schemes with a minimum number of external
components. This integrated circuits features
an undervoltage lockout (UVLO) with
approximately 300µA start-up current, a
precision reference trimmed for accuracy at the
error amplifier input, high gain error amplifier,
current sensing comparator, logic to insure
latched operation, and a totem-pole output
stage designed to source or sink high peak
current. The output stage, suitable for driving N
channel MOSFETs, is low in the off state.

n TYPICAL APPLICATION CIRCUIT

M1C3
1000P
C2
300pF
C6
300P
RS
0.33
R2
20K
R4
7.5K
R1
10
R5
390
R3
51K
C5
0.1µF C4
2.2nF
C7
1nF
+ C1
47µF
COMP
VREF
AIC3842
INDUCTOR
FEEDBACK
SIGNAL
VCC7
6
5
34
8
1
2 VCC
OUTPUT
RT/CT
GND
ISENSE
VFB
Current Mode PWM Control Circuit

n ORDERING INFORMATION

PACKAGE TYPE
N: PLASTIC DIP
S: SMALL OUTLINE
ORDER NUMBER
AIC3842CN
(PLASTIC DIP)
PIN CONFIGURATIONAIC3842CX
1
3
2
4
COMP
VFB
ISENSE
RT/CT GND
VREF
VCC
OUTPUT
5
8
7
6
AIC3842CS
(PLASTIC SO)