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