The AD590 is a 2-terminal integrated circuit temperature transducer that produces an output current proportional to absolute temperature. For supply voltages between 4 V and 30 V, the device acts as a high impedance, constant current regulator passing 1 A/K. Laser trimming of the chip's thin-film resistors is used to calibrate the device to 298.2 A output at 298.2 K (25C).