A good PCB layout for the MP28251GD-Z should include a solid ground plane, wide power traces, and a thermal relief pattern under the IC. A 4-layer PCB with a dedicated power plane and a solid ground plane is recommended. Additionally, a thermal pad should be connected to a solid ground plane to improve thermal performance.
To optimize output voltage accuracy, ensure that the feedback resistors (R1 and R2) are of high precision (1% or better) and have a low temperature coefficient. Also, use a high-quality output capacitor with low ESR and a stable dielectric material. Finally, minimize the noise on the FB pin by using a low-noise voltage reference and a quiet power supply.
A low-ESR ceramic capacitor (X5R or X7R dielectric) with a value of 4.7uF to 10uF is recommended for the input capacitor. This type of capacitor provides low impedance and high reliability. Avoid using electrolytic capacitors as they have higher ESR and may cause instability.
To ensure stability, ensure that the output capacitor has a low ESR and a high-quality dielectric material. Also, use a compensation network (R3 and C3) to stabilize the loop. A good starting point for the compensation network is R3 = 1kΩ and C3 = 10nF. Adjust these values as needed to achieve a stable response.
The MP28251GD-Z is rated for operation up to 85°C ambient temperature. However, for reliable operation, it is recommended to keep the ambient temperature below 70°C to ensure a safe margin for thermal derating.
MP28251GD-Z datasheet
by Monolithic Power Systems
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