LT1185 3A Adjustable Low Drop-out Regulator

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The LT1185 uses a saturation-limited NPN transistor as the pass element. This device gives the linear dropout characteristics of an FET pass element with significantly less die area. High efficiency is maintained by using special anti-saturation circuitry that adjusts base drive to track load current. The “on resistance” is typically 0.25Ω. Accurate current limit is programmed with a single 1/8W external resistor, with a range of zero to three amperes. A second, fixed internal limit circuit prevents destructive currents if the programming current is accidentally over ranged. Shutdown of the regulator output is guaranteed when the program current is less than 1µA, allowing external logic control of output voltage.