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Precision Current Control
鹵
450mA Load Current
1.2V Typical Total Vsat at
450mA
Programmable Over-Current
Control
Range Control for 4:1 Gain
Change
Compensation Adjust Pin for
Range Bandwidth Control
Inhibit Input and UVLO
3V to 15V Operation
12mA Quiescent Supply
Current
DESCRIPTION
The UC3178 full-bridge power amplifier, rated for continuous output current
of 0.45 Amperes, is intended for use in demanding servo applications. This
device includes a precision current sense amplifier that senses load current
with a single resistor in series with the load. The UC3178 is optimized to con-
sume a minimum of supply current, and is designed to operate in both 5V
and 12V systems. The power output stages have a low saturation voltage
and are protected with current limiting and thermal shutdown. When inhibited,
the device will draw less than 1.5mA of total supply current.
Auxiliary functions on this device include a load current sensing and rectifica-
tion function that can be configured with the device鈥檚 over-current comparator
to provide tight control on the maximum commanded load current. The closed
loop transconductance of the configured power amplifier can be switched be-
tween a high and low range with a single logic input. The 4:1 change in gain
can be used to extend the dynamic range of the servo loop. Bandwidth vari-
ations that would otherwise result with the gain change can be controlled with
a compensation adjust pin.
This device is packaged a power PLCC, "QP" package which maintains a
standard 28-pin outline, but with 7 pins along one edge directly tied to the die
substrate for improved thermal performance.
BLOCK DIAGRAM
UDG-92010
5/93
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