LM334

LM134/LM234/LM334 3-Terminal Adjustable Current Sources March 2000 LM134/LM234/LM334 3-Terminal Adjustable Current Sources General Description The LM134/LM234/LM334 are 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 LM134/LM234/LM334 are 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. 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 ≈+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 LM234-3 and LM234-6 are specified as true temperature sensors with guaranteed initial accuracy of ± 3˚C and ± 6˚C, respectively. These devices are ideal in remote sense applications because series resistance in long wire runs does not affect accuracy. In addition, only 2...