1117s

1117s refers to a family of low-dropout linear voltage regulators (LDOs) commonly found in electronics. The most widely known members include the AMS1117 and its clones (such as LM1117, LD1117). The family encompasses both fixed-output versions and an adjustable variant that uses external resistors to set the desired voltage. Fixed versions are popular values, most notably 3.3 V and 5.0 V, while the adjustable version typically covers a wide range of outputs around 1.25 V to about 12 V.

Key characteristics and usage: 1117 regulators operate from a higher input voltage and provide a stable lower output voltage. They have a fixed reference voltage between the output and adjust pin (for adjustable parts) and require external resistors to set the target voltage. The input voltage is commonly up to about 15 V, and the dropout voltage at moderate current is roughly 1.1–1.3 V, increasing with load. The devices can deliver up to approximately 1 A with adequate heat sinking, but thermal limitations may reduce current handling in compact packages.

Stability and external components: Proper operation requires input and output capacitors, typically around 10 μF on both sides, chosen to meet ESR requirements for stability. Capacitor type and placement near the regulator are important for reliable operation.

Packages and availability: 1117 regulators are produced in several packages, including TO-220, SOT-223, and SOT-89, by many manufacturers. They are widely used in hobbyist and commercial electronics to generate regulated 5 V or 3.3 V rails, serve as adjustable regulators, or act as simple, low-cost power supplies for microcontrollers and peripheral circuits.