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GM384X Datasheet, PDF (1/8 Pages) Gamma Microelectronics Inc. – Low Start-Up and Operating Current
GM3842A, GM3843A
GM3844A, GM3845A
CURRENT MODE PWM CONTROLLER
Description
Features
GM384XA series is high performance with fixed-
frequency current mode PWM controllers. They
are specially designed for off-Line and DC-to-DC
converter applications with minimum 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.
 Low Start-Up and Operating Current
 Automatic Feed Forward Compensation
 Current Mode Operating Frequency up to
500KHz
 Trimmed Oscillator Discharge Current for
Precise Duty Cycle Control
 Latching PWM for Cycle-By-Cycle
Current Limiting
The under voltage lock-out (U.V.L.O.) is
designed to operated with 0.17mA 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
GM3843A/45A is 8.4V (on) and 7.6V (off). The
GM3842A/43A can operated within 100% duty
cycle and the GM3844A/45A can operated within
50% duty cycle.
 Under Voltage Lockout with Hysteresis
 High Current totem Pole Output Stage
Available Options
Application
Device
GM3842A
GM3843A
GM3844A
GM3845A
Start-UP
Voltage
16V
8.4V
16V
8.4V
Hysteresis
Max. Duty
Cycle
6V
0.8V
6V
0.8V
< 100%
< 100%
< 50%
< 50%
C Off-line flyback or forward converters
N DC-to DC buck boost converter
Monitor Power Supply
O
N
GP O
O
G
C
C
UNW M
U
N
TDR P
T
D
P
P
U
U
G
T
T
www.gammamicro.com.tw 1
N