GM7500
PULSE-WIDTH-MODULATION
CONTROL CIRCUITS
Description
The KA7500 incorporate on a single monolithic
chip all the functions required in the construction
of a pulse-width-modulation control circuit.
Designed primarily for power supply control,
these devices offer the systems engineer the
flexibility to tailor the power supply control
circuitry to his application.
The KA7500 contains an error amplifier, an on-
chip adjustable oscillator, a dead-time control
comparator, pulse-steering control flipflop, a 5-
volt, 1% precision regulator, and output-control
circuits. The error amplifier exhibits a common-
mode voltage range from -0.3 volts to VCC -2
volts. The dead-time control comparator has a
fixed offset that provides approximately 5% dead
time when externally altered. The on-chip
oscillator may be bypassed by terminating RT
(pin 6) to the reference output and providing a
sawtooth input to CT (pin 5), or it may be used to
drive the common circuits in synchronous
multiple-rail power supplies. The uncommitted
output transistors provide either common-emitter
or emitter-follower output capability. Each device
provides for push-pull or single-ended output
operation, which may be selected through the
output-control function. The architecture of these
devices prohibits the possibility of either output
being pulsed twice during push-pull operation.
Features
High Current totem Pole Output Stage
Complete PWM Power Control Circuitry
Uncommitted Outputs for 200 mA Sink
or Source Current
Output Control Selects Single-Ended or
Push-Pull Operation
Internal Circuitry Prohibits Double Pulse
at Either Output
Variable Dead-Time Provides Control
over Total Range
Internal Regulator Provides a Stable 5-V
Reference Supply, 1%
Circuit Architecture Allows Easy
synchronization
Functional Block Diagram
Output
Control
R
T
C
T
Oscillator
Pulse Steering
Flip-Flop
≈
0.1V
Dead Time Control
Comparator
C1
E1
C2
E2
Dead Time
Control
Non Inverting
Input
Inverting
Input
Non Inverting
Input
Inverting
Input
Error
Amplifier 1
PWM
Comparator
Reference
Feedback
Error
Amplifier 2
V
REF
GND
www.gammamicro.com.tw
1
GM7500
V1.00
V
CC
GAMMA [ GAMMA MICROELECTRONICS INC. ]
