> ## Documentation Index
> Fetch the complete documentation index at: https://learn.pcbcupid.com/llms.txt
> Use this file to discover all available pages before exploring further.

> The SY81103 DC-DC Buck Converter is a high-efficiency module that steps down input voltage (9V–18V) to a stable 3.3V, 5V, or an adjustable range for electronic devices.

# DC-DC Buck Converter (SY81103)

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            3D VIEW
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<ShopHeader title="SY81103 DC-DC Buck Converter" url="https://shop.pcbcupid.com/product/gm015/" />

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The **SY81103 DC-DC Buck Converter** is a compact, high-efficiency power conversion module designed to reduce a higher input voltage to a stable lower output voltage. Built around the **SY81103** synchronous step-down IC, it ensures minimal power loss and high performance, making it ideal for battery-powered and industrial applications.

***

## Product Variants

To accommodate different system requirements, this module is available in three distinct variants:

1. **Fixed 3.3V Output**: Pre-configured to provide a steady 3.3V DC output.
2. **Fixed 5V Output**: Pre-configured to provide a steady 5V DC output.
3. **Variable Output**: Features an adjustable output range from **1.2V to 5V** using an onboard potentiometer.

***

## Key Features

* **SY81103 High-Efficiency IC**: Synchronous rectification technology for cool operation.
* **Wide Input Range**: Supports input voltages from **9V to 18V**.
* **High Load Capacity**: Delivers up to **3A** output current.
* **Stable 500kHz Frequency**: Ensures low ripple and high efficiency.
* **Protection**: Includes cycle-by-cycle current limit and thermal shutdown.
* **Compact G-Mod Footprint**: Designed to fit seamlessly onto Glyph development boards.

***

## Technical Specifications

| Parameter                   | Operating Range                               |
| :-------------------------- | :-------------------------------------------- |
| **Input Voltage (V\_IN)**   | 9.0V – 18.0V DC                               |
| **Output Voltage (V\_OUT)** | 1.2V – 5.0V DC (Variable) / 3.3V & 5V (Fixed) |
| **Output Current**          | Up to 3.0A                                    |
| **Switching Frequency**     | 500 kHz                                       |
| **Peak Efficiency**         | Up to 95%                                     |
| **Integrated IC**           | SY81103                                       |

***

## Pin Configuration

The module features input and output terminal blocks for easy integration:

**Left Side – INPUT**

* **VIN (+)** → DC Input Supply (**9V – 18V**)
* **GND (–)** → DC Input Ground

**Right Side – OUTPUT**

* **VOUT (+)** → Regulated DC Output (**3.3V / 5V / 1.2V–5V**)
* **GND (–)** → Output Ground

***

## Applications

* **IoT & Sensors**: Powers microcontrollers and sensors from 12V batteries.
* **Industrial Automation**: Provides stable control-line power in noisy environments.
* **Automotive Electronics**: Regulates 12V vehicle power for sensitive electronics.
* **Battery Management**: Efficiently steps down Li-ion battery pack voltages (3S/4S).
* **Prototyping**: Ideal for breadboard and custom PCB power distribution.

<Info>
  Please ensure you choose the correct variant (Fixed or Variable) based on your specific application needs.
</Info>

***

## Step 1: Hardware Required

1. SY81103 DC–DC Buck Converter Module (Variant-specific)
2. DC Power Supply (9V – 18V)
3. Multimeter (for Variable variant calibration)
4. Jumper Wires / Connecting Wires

***

## Step 2: Circuit Connection

Connect the input source to the input terminals. For the variable variant, it is recommended to adjust the potentiometer **before** connecting your final load.

<Warning>
  Ensure the input polarity is correct before powering the module. Reverse polarity can permanently damage the SY81103 IC.
</Warning>

![DC-DC CONVERTER DIAGRAM](https://files.pcbcupid.com/Documentation/Boards/g-mod/Buck-convertor/buck_converter_circuit.avif)

***

## Step 3: Observe the Output

1. **Verify Input**: Use a multimeter to confirm your input voltage is within the **9V–18V** range.
2. **Set Output (Variable Variant Only)**: Rotate the onboard potentiometer until the desired voltage (e.g., 3.3V or 5V) is reached.
3. **Confirm Stability**: Check that the output remains stable even when the load is connected.
4. **Thermal Check**: The module is designed for low heat generation, but ensure adequate airflow if drawing the full 3A current for extended periods.