LM134/LM234/LM334 Adjustable Current Sources

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.

Features

• Operates from 1V to 40V
• 0.02%/V current regulation
• Programmable from 1µA to 10mA
• True 2-terminal operation
• Available as fully specified temperature sensor
• ±3% initial accuracy

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 [Approximate]+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 wires are required.
The LM134 is guaranteed over a temperature range of -55°C to +125°C, the LM234 from -25°C to +100°C and the LM334 from 0°C to +70°C. These devices are available in TO-46 hermetic, TO-92 and SO-8 plastic packages.