A good PCB layout for the VN751S involves keeping the high-current paths short and wide, using a solid ground plane, and placing the device close to the battery. A 2-layer or 4-layer PCB is recommended. STMicroelectronics provides a reference design and layout guidelines in their application notes.
The VN751S has a built-in thermal protection feature, but it's still important to ensure good heat dissipation. Use a heat sink with a thermal resistance of 10°C/W or lower, and apply a thermal interface material (TIM) between the device and heat sink. Ensure good airflow around the device and avoid blocking the heat sink's airflow.
For the input capacitor, use a low-ESR ceramic capacitor (e.g., X5R or X7R) with a value of 10-22 μF and a voltage rating of 25-50 V. For the output capacitor, use a low-ESR ceramic capacitor with a value of 10-47 μF and a voltage rating of 16-25 V. The capacitor values may vary depending on the specific application and requirements.
The VN751S is a highly configurable device. To configure it for a specific application, refer to the datasheet and application notes for guidance on setting the input voltage, output voltage, and current limits. You may need to adjust the resistors and capacitors in the feedback network, as well as the input and output capacitors, to achieve the desired performance.
To ensure EMC compliance, follow proper PCB layout and design practices, such as using a solid ground plane, minimizing loop areas, and using shielding and filtering components as needed. Additionally, ensure that the VN751S is properly decoupled and that the input and output filters are designed to meet the relevant EMC standards (e.g., CISPR 25).
VN751S datasheet
by STMicroelectronics
