REG1117

REG1117 is a family of three-terminal low-dropout (LDO) voltage regulators. They come in fixed outputs (e.g., 3.3 V, 5 V, 1.8 V) or adjustable versions and can deliver about 1 A. Dropout is ~1 V at full load; quiescent current is a few mA. Input voltage range is up to roughly 15 V, depending on variant.
Pinout (typical SOT-223/TO-252, view from front): left = ADJ (or GND for fixed), middle = Vout, right = Vin. Verify with the datasheet for your package.
Requirements: use input and output capacitors (usually 10 μF or larger, low ESR); a 0.1 μF ceramic close to the device is also recommended. For adjustable versions: Vout = Vref (1.25 V) × (1 + R2/R1) + Iadj×R2.
Thermals: P = (Vin − Vout) × Iout; provide heat sinking or adequate copper area for significant drops.
Applications: supplying microcontrollers, sensors, and other circuitry from higher-voltage sources. Note that “REG1117” naming varies by vendor; many parts are AMS1117/LD1117 variants—check the datasheet.

REG1117 is a 1 A low-dropout regulator in the 1117 family. Common equivalents:
- LM1117 (TI)
- AMS1117 (Analog Devices / clones)
- LD1117 (ST)
- NCP1117 (ON Semiconductor)
- KA1117 (various suppliers)
Fixed-output variants: LM1117-5.0, LM1117-3.3 (also AMS1117-5.0/3.3, LD1117-5.0/3.3).
Adjustable variants: LM1117-ADJ, AMS1117-ADJ. (Pinouts typically compatible.)

REG1117 features (typical AMS1117/LM1117 family):
- 1 A maximum output current; fixed and adjustable versions (e.g., fixed 3.3 V, 5.0 V, 2.5 V, 1.8 V, etc.; adjustable via resistors)
- Input voltage up to 15 V
- Low dropout: ~1.1–1.3 V at 1 A
- Requires output capacitor for stability (typically ≥ 10 µF; ESR roughly 0.1–22 Ω)
- Internal current limit and thermal (overload) shutdown protection
- Quiescent current ≈ 5 mA
- Pinout (front view, 3 pins): ADJ/GND, Vout, Vin (tab is Vout; pinout may vary by package)
- Packages: TO‑220, SOT‑223, etc.
- Temperature range commonly -40°C to +125°C
Notes: Vout of adjustable version follows Vout = 1.25 × (1 + R2/R1) + Iadj × R2.

- Pin count: 3 pins (three-terminal regulator). In common SOT‑223/TO‑263 packages: Pin 1 = Ground/Adj, Pin 2 = Vout, Pin 3 = Vin (tab tied to Vin on most variants).
- Function: A low‑dropout linear regulator (REG1117 family) that converts a higher input voltage to a stable lower output voltage (fixed versions like 3.3V/5.0V or adjustable via the Adj pin). Typical dropout ~1.1–1.3V depending on current.

REG1117 is a family of low-dropout linear regulators (approx. 1 A) with fixed outputs (3.3 V, 5 V, 1.8 V, etc.) and an adjustable version. Common applications:
- Stable rails for microcontrollers, memories, ASICs/FPGA logic in embedded systems
- Post-regulation from higher rails (5–12 V) to 3.3 V/5 V/1.8 V
- USB-powered devices and peripherals needing clean 5 V or 3.3 V
- Battery-powered equipment (IoT sensors, portable meters, wearables) from Li‑ion cells
- General purpose onboard regulators in consumer electronics, routers, displays, and industrial equipment

REG1117 is a 3‑terminal LDO regulator. The most common package is SOT-223; it is also available in SOT‑89 and TO‑220 variants.