AMS1117 Pinout
AMS1117 LDO Regulator · Common low-dropout linear regulator, fixed 3.3V/5V/1.8V or adjustable; very common on modules.
SOT-223: with the printed face toward you and the pins down, left to right is GND(ADJ)-VOUT-VIN; the large tab on the back is internally connected to VOUT. The fixed and adjustable versions define pin 1 differently (GND vs ADJ).
| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | GND · ADJ | GND | Ground (ADJ adjust pin on the adjustable version) |
| 2 | VOUT | Output | Regulated output (connected to the back tab) |
| 3 | VIN | Power | Input voltage (about ≥1.1V dropout above the output) |
How to read the AMS1117 pinout
- 01
Find pin 1
One end of the chip has a half-circle notch or a dot; with the notch facing up, the top-left pin is pin 1.
- 02
Count counter-clockwise
Count counter-clockwise from pin 1: go down the left side first, then up the right side from the bottom.
- 03
Check the table below
Look up each pin's function by number in the table below; power/ground are color-coded, and alternate-function signals are in parentheses.
Frequently asked questions
What's the AMS1117 dropout, and does it need a heatsink?
Dropout is about 1.1–1.3V (not ultra-low); (Vin−Vout)×current all turns into heat; e.g. 5V→3.3V at 800mA gets noticeably hot, dissipating heat through PCB copper / the tab.
Do I need capacitors?
Place a capacitor (commonly 10–22µF) on both the input and output; the output capacitor is required for loop stability, see the datasheet.
Maximum output current?
Typically 1A (limited by heat dissipation); its quiescent current is fairly high, drawing a few mA even at no load, so be careful in battery-powered applications.
Pinout data comes from AMS/Advanced Monolithic AMS1117 datasheet (standard SOT-223 numbering). Refer to the actual device datasheet as authoritative for the pinout.