GM3842A, GM3843A
GM3844A, GM3845A
CURRENT MODE PWM CONTROLLER
Description
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.
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.
Features
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
Under Voltage Lockout with Hysteresis
High Current totem Pole Output Stage
Available Options
Device
GM3842A
GM3843A
GM3844A
GM3845A
Start-UP
Voltage
16V
8.4V
16V
8.4V
Hysteresis
6V
0.8V
6V
0.8V
Max. Duty
Cycle
< 100%
< 100%
< 50%
< 50%
Application
Off-line flyback or forward converters
DC-to DC buck boost converter
Monitor Power Supply
www.gammamicro.com.tw
1
GM384x
V1.00
GAMMA [ GAMMA MICROELECTRONICS INC. ]
