Features

• Linear Current Output . . . . . . . . . . . . . . . . . . . . .1A/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

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 1A/oK for supply voltages between

+4V and +30V. Laser trimming of the chip's thin film resistors is

used to calibrate the device to 298.2A 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 o