3 Description

The LM1086 is a regulator with a maximum dropout of 1.5 V at 1.5 A of load current. The device has the same pin-out as TI's industry standard LM317.

Two resistors are required to set the output voltage of the adjustable output voltage version of the LM1086. Fixed output voltage versions integrate the adjust resistors. Typically, no input capacitor is needed unless the device is situated more than 6 inches from the input filter capacitors. Output capacitor can be replaced with ceramic and appropriate ESR.

The LM1086 circuit includes a zener trimmed bandgap reference, current limiting, and thermal shutdown. Because the LM1086 regulator is floating and detects only the input-to-output differential voltage, supplies of several hundred volts can be regulated as long as the maximum input-to-output differential is not exceeded. Exceeding the maximum input-to-output deferential will result in short-circuiting the output. By connecting a fixed resistor between the adjustment pin and output, the LM1086 can be also used as a precision current regulator.

For applications requiring greater output current, refer to LM1084 (clickable link) for the 5-A version, and the LM1085 (clickable link) for the 3-A version.

1. For all available packages, see the orderable addendum at the end of the datasheet.