The **S1117API** is a specific part number within the 1117 family of **Low Dropout (LDO) linear voltage regulators**. It is commonly manufactured by companies like *AUK Corp* or *Kodenshi*. Below is a detailed breakdown of its electronic characteristics and specifications. --- ## 1. Core Function and Architecture The S1117API is designed to provide a stable, constant output voltage from a higher, fluctuating input voltage. Unlike standard regulators (like the 7805), LDOs can operate even when the input voltage is only slightly higher than the output voltage. ### Key Specifications Table | Feature | Specification | | :--- | :--- | | **Output Type** | Adjustable (ADJ) or Fixed (typically 3.3V, 5V, etc.) | | **Max Output Current** | 1.0 Ampere | | **Dropout Voltage** | Typically 1.2V at 1A | | **Max Input Voltage** | 15V (Recommended 12V max) | | **Package Type** | TO-220FP (Full Plastic) | | **Operating Temp** | -40°C to +125°C | --- ## 2. Pin Configuration The S1117API usually follows the industry-standard pinout for the 1117 series in a 3-pin package: 1. **ADJ / GND**: For the adjustable version, this connects to a voltage divider; for fixed versions, it connects to Ground. 2. **Output (Vout)**: The regulated voltage output. 3. **Input (Vin)**: The unregulated supply voltage. --- ## 3. Package Significance: The "API" Suffix The suffix **"API"** is critical for hardware design: * **A**: Often denotes a specific performance grade or manufacturer series. * **PI**: Typically refers to the **TO-220FP** package. The "FP" stands for **Full Plastic** or **Fully Insulated**. * **Advantage**: Unlike a standard TO-220 (which has a metal tab connected to Vout), the API package is encased in plastic. You can mount it directly to a heatsink without needing an insulating mica washer or thermal pad to prevent short circuits. --- ## 4. Typical Application Circuit To ensure stability, the S1117 series requires external capacitors. ```c Vin ----[ S1117API ]---- Vout | | C1 (In) C2 (Out) | | GND ------+----+------- GND ``` * **Input Capacitor (C1):** 10µF Tantalum or Electrolytic (removes noise from the source). * **Output Capacitor (C2):** 10µF to 22µF Tantalum (essential for frequency stability). --- ## 5. Thermal Considerations Since it is a linear regulator, it dissipates excess voltage as heat. **Formula:** $P_{dissipated} = (V_{in} - V_{out}) \times I_{out}$ Because the TO-220FP (API) package is plastic-molded, its thermal resistance ($\theta_{JC}$) is slightly higher than the metal-tab version. Proper heatsinking is required if the voltage drop or current is high.