Description
The AD590 is an integrated-circuit temperature transducer
which produces an output current proportional to absolute temperature. The device acts as a high impedance constant current
regulator, passing 1µA/oK for supply voltages between +4V and
+30V. Laser trimming of the chip's thin film resistors is used to
calibrate the device to 298.2µA output at 298.2oK (25oC).
The AD590 should be used in any temperature-sensing
application between -55oC to 150oC in which conventional
electrical temperature sensors are currently employed. The
inherent low cost of a monolithic integrated circuit combined
with the elimination of support circuitry makes the AD590 an
attractive alternative for many temperature measurement situations. Linearization circuitry, precision voltage amplifiers,
resistance measuring circuitry and cold junction compensation are not needed in applying the AD590. In the simplest
application, a resistor, a power source and any voltmeter can
be used to measure temperature.
In addition to temperature measurement, applications include
temperature compensation or correction of discrete
components, and biasing proportional to absolute temperature.
The AD590 is particularly useful in remote sensing applications. The device is insensitive to voltage drops over long
lines due to its high-impedance current output. Any well
insulated twisted pair is sufficient for operation hundreds of
feet from the receiving circuitry. The output characteristics
also make the AD590 easy to multiplex: the current can be
switched by a CMOS multiplexer or the supply voltage can
be switched by a logic gate output.

Features
• Linear Current Output . . . . . . . . . . . . . . . . . . . . 1µA/oK
• Wide Temperature Range . . . . . . . . . . . -55oC to 150oC
• Two-Terminal Device Voltage In/Current Out
• Wide Power Supply Range . . . . . . . . . . . . . +4V to +30V
• Sensor Isolation From Case
• Low Cost