Low drop fixed and adjustable positive voltage regulators application note (PDF!) from ST:
The LD1117A is a low drop voltage regulator able to provide up to 1 A of output current, available also in adjustable versions (VREF = 1.25 V). In fixed versions, the following output voltages are offered: 1.2 V, 1.8V, and 3.3 V. The device is supplied in: SOT-223, DPAK and TO-220. Surface mounted packages optimize the thermal characteristics while offering a relevant space saving advantage. High efficiency is assured by an NPN pass transistor. Only a very common 10 μF minimum capacitor is needed for stability. Chip trimming allows the regulator to reach a very tight output voltage tolerance, within ± 2% at 25 °C.
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