
UC1638
UC2638
UC3638
1/98
BLOCK DIAGRAM
Single or Dual Supply Operation
Accurate High Speed Oscillator
Differential X5 Current Sense
Amplifier
Bidirectional Pulse-by-Pulse
Current Limiting
Programmable Oscillator
Amplitude and PWM Deadband
Dual 500mA Totem Pole Output
Drivers
Dual 60V, 50mA Open Collector
Drivers
Undervoltage Lockout
Advanced PWM Motor Controller
FEATURES
DESCRIPTION
The UC1638 family of integrated circuits are advanced pulse width modula-
tors intended for a variety of PWM motor drive and amplifier applications re-
quiring either uni-directional or bi-directional drive circuits. Similar in
architecture to the UC1637, all necessary circuitry is included to generate an
analog error signal and modulate two bi-directional pulse train outputs in pro-
portion to the error signal magnitude and polarity.
UDG-95048-4
Key features of the UC1638 include a programmable high speed triangle os-
cillator, a 5X differential current sensing amplifier, a high slew rate error am-
plifier, high speed PWM comparators, and two 50mA open collector as well
as two
±
500mA totem pole output stages. The individual circuit blocks are
designed to provide practical operation to switching frequencies of 500kHz.
Significant improvements in circuit speed, elimination of many external pro-
gramming components, and the inclusion of a differential current sense am-
plifier,
allow
this
controller
to
be
applications, yet maintain the flexibility of the UC1637. The current sense
amplifier in conjunction with the error amplifier can be configured for average
current feedback. The additional open collector outputs provide a drive signal
specified
for
higher
performance
continued
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