LM3411 Datasheet | National Semiconductor

Description The LM3411 is a low power fixed-voltage (3.3V or 5.0V) precision shunt regulator designed specifically for driving an optoisolator to provide feedback isolation in a switching regulator. The LM3411 circuitry includes an internally pensated op amp, a bandgap reference, NPN output transistor, and voltage setting resistors. A trimmed precision bandgap reference with temperature drift curvature correction, provides a guaranteed 1% precision over the operating temperature range (A grade version). The amplifier’s inverting input is externally accessible for loop frequency pensation when used as part of a larger servo system. The output is an open-emitter NPN transistor capable of driving up to 15 m A of load current. Because of its small die size, the LM3411 has been made available in the sub-miniature 5-lead SOT23-5 surface mount package. This package is ideal for use in space critical applications. Although its main application is to provide a precision output voltage (no trimming required) and maintain very good regulation in isolated DC/DC converters, it can also be used with other types of voltage regulators or power semiconductors to provide a precision output voltage without precision resistors or trimming. Features n Fixed voltages of 3.3V and 5.0V with initial tolerance of ± 1% for standard grade and ± 0.5% for A grade n Custom voltages available (3V- 17V) n Wide output current range, 20 µA- 15 m A n Low temperature coefficient n Available in 5-lead SOT23-5 surface mount package (tape and reel) Applications n Secondary controller for isolated DC/DC PWM switching regulators systems n Use with LDO regulator for high-precision fixed output regulators n Precision monitoring applications n Use with many types of regulators to increase precision and improve performance Typical Application and Functional Diagram DS011987-1 Basic Isolated DC/DC Converter DS011987-2 LM3411 Functional Diagram SIMPLE SWITCHER™ is a tradmark of National Semiconductor...