This integrated circuit contains a complete signal conditioning sys-

tem to interface low-level variable impedance transducers to a

digital system. A pair of matched, temperature-compensated cur-

rent sources are provided for balanced transducer excitation fol-

lowed by a precision, high-gain comparator. The output of this

comparator can be delayed by a user-selectable duration, after

which a second comparator will switch complementary outputs

separately activated for diagnostic operation and has an optional

latch with external reset capability. An added feature is a high cur-

rent power source useful as a heater driver in differential tempera-

ture sensing applications. The UC3704 is designed for 0°C to

+70°C environments.

Bridge Transducer Switch

UC3704

SENSOR TYPE

ACTIVATION SOURCE

Temperature

Pressure

Force

Position

Displacement

Velocity

Shock

Thermistor

X

X

Sensistor

X

X

Thermocouple

X

Semiconductor

X

X

X

Photo Voltaic

X

X

X

Photo Resistive

X

X

X

Strain Gage

XXXXXX

Piezoelectric

X

X

X

X

X

Magneto Resistive

X

X

Inductive

XXXX

Hall Effect

X

X

Capacitive

X

•

Dual Matched Current Sources

•

High-gain Differential Sensing Circuit

•

Wide Common-mode Input Capability

•

Complementary Digital Open-collector

Outputs

•

Externally Programmable Time Delay

•

Optional Output Latch with Reset

•

Built-in Diagnostic Activation

•

Wide Supply Voltage Range

•

High Current Heater Power Source Driver

UC3704 COMPATIBLE SENSORS

BLOCK DIAGRAM

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FEATURES

DESCRIPTION