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LT3085 - Adjustable 500mA Single Resistor Low Dropout Regulator

The LT3085 is a 500mA low dropout linear regulator that can be paralleled to increase output current or spread heat on surface mounted boards. Designed as a precision current source and voltage follower, this new regulator finds use in many applications requiring high current, adjustability to zero, and no heat sink. The device also brings out the collector of the pass transistor to allow low dropout operation—down to 275mV—when used with a second supply.

A key feature of the LT3085 is the capability to supply a wide output voltage range. By using a reference current through a single resistor, the output voltage is programmed to any level between zero and 36V. The LT3085 is stable with 2.2μF of capacitance on the output, and the IC uses small ceramic capacitors that do not require additional ESR as is common with other regulators.

Internal protection circuitry includes current limiting and thermal limiting. The LT3085 is offered in the 8-lead MSOP and a low profile (0.75mm) 6-lead 2mm × 3mmDFN package (both with an Exposed Pad for better thermal characteristics).

Features Outputs May be Paralleled for Higher Current and Heat Spreading Output Current: 500mA Single Resistor Programs Output Voltage 1% Initial Accuracy of SET Pin Current Output Adjustable to 0V Current Limit Constant with Temperature Low Output Noise: 40μVRMS (10Hz to 100kHz) Wide Input Voltage Range: 1.2V to 36V Low Dropout Voltage: 275mV < 1mV Load Regulation < 0.001%/ V Line Regulation Minimum Load Current: 0.5mA Stable with Minimum 2.2μF Ceramic Capacitor Current Limit with Foldback and Overtemperature Protected 8-Lead MSOP, and 6-Lead 2mm × 3mm DFN Packages Typical Application

Applications High Current All Surface Mount Supply High Efficiency Linear Regulator Post Regulator for Switching Supplies Low Parts Count Variable Voltage Supply Low Output Voltage Power Supplies Packaging

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