AMC DOC. #: AMC3842A_A
November 2001
Copyright 2001, ADD Microtech Corp. 1 www.addmtek.c om
DESCRIPTION FEATURES
The AMC3842A/43A/44A/45A are fixed frequency
current-mode PWM controllers specially designed for
OFF-Line switching power supply and DC-to-DC converters
with a minimum number of external components. These
devices feature a trimmed oscillator for precise duty cycle
control, a temperature compensated reference, high gain
error amplifier, current sensing comparator, and high current
totem pole output which is suitable for driving MOSFETs.
The under voltage lock-out (U.V.L.O.) is designed to
operated with 200µA typ. start-up current, allowing an
efficient bootstrap supply voltage design. The U.V.L.O.
thresholds for the AMC3842A/44A are 16V (on) and 10V
(off) which are ideal for off-line applications. The
corresponding typical threshold for the AMC3843A/45A are
8.4V (on) and 7.6V (off). The AMC3842A/43A can
operated within 100% duty cycle and the AMC3844A/45A
can operated within 50% duty cycle.
! Low Start-Up current ( typ. 200µ
µµ
µA)
! Optimized for Off-Line and
DC-to-DC Converters
! Maximum Duty Cycle
! U.V.L.O. with Hysteresis
# Operating Frequency Up to 500KHz
# Internal Trimmed Bandgap Reference
# High Current Totem Pole Output
# Error Amplifier With Low Output
Resistance
# Available in 8-Pin Plastic DIP and
Surface Mount 14-Pin S.O.I.C.
# Identical pin assignment to earlier
UC384X series.
APPLICATIONS PACKAGE PIN OUT
! Off-line flyback or forward
converters.
! DC-to-DC buck or boost
converter.
! Monitor Power Supply
8-Pin Plastic DIP
(Top View)
AVAILABLE OPTIONS
Device Start-UP
Voltage Hysteresis Max. Duty
Cycle
AMC3842A 16V 6V < 100%
AMC3843A 8.4V 0.8V < 100%
AMC3844A 16V 6V < 50%
AMC3845A 8.4V 0.8V < 50%
14-Pin Plastic S.O.I.C.
Surface Mount
To
View
8-Pin Plastic S.O.I.C.
Surface Mount
(Top View)
ORDER INFORMATION
Plastic DIP-8 Plastic SO-14 Plastic SO-8
TA (OC) M 8-pin D 14-pin DM 8-pin
0 to 70 AMC384XAM AMC384XAD AMC384XADM
Note: All surface-mount packages are available in Tape & Reel. Append the letter “T” to part number (i.e.
AMC384XADT, or AMC384XADMT).
CURRENT MODE PWM CONTROLLER
AMC3842A/43A/44A/45A
COMP
VFB
ISENSE
VREF
GND
OUTPUT
VCC
RT/CT
NC
NC
RT/CT
ISENSE
VFB
VREF
VCC
VC
OUTPUT
GND
PWR
NC
NC
COMP
COMP
VFB
ISENSE
VREF
GND
OUTPUT
VCC
RT/CT
A
AA
ADD MICROTECH CORP.