LM334Z (LT65-5201) 3-Terminal Adjustable Current Sources
The LM334 is a 3-terminal adjustable current sources featuring 10,000:1 range in operating current, excellent current regulation and a wide dynamic voltage range of 1V to 40V. Current is established with one external resistor and no other parts are required. Initial current accuracy is ±3%. The LM334 is a true floating current sources with no separate power supply connections. In addition, reverse applied voltages of up to 20V will draw only a few dozen microamperes of current, allowing the devices to act as both a rectifier and current source in AC applications. (LT65-5201 Linear Tech)
The sense voltage used to establish operating current in the LM134 is 64mV at 25°C and is directly proportional to absolute temperature (°K). The simplest one external resistor connection, then, generates a current with about +0.33%/°C temperature dependence. Zero drift operation can be obtained by adding one extra resistor and a diode.
Applications for the current sources include bias networks, surge protection, low power reference, ramp generation, LED driver, and temperature sensing. The LM334 is guaranteed over a temperature range 0°C to +70°C. These devices are available in TO-92 and SO-8 plastic packages.