Power supply obstacles + power supply SBC selection and pitfalls

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Power supply obstacles + power supply SBC selection and pitfalls [Copy link]

Hello everyone, I am an automotive electronics hardware engineer.

When selecting a power SBC, you should pay attention to the battery voltage range and then combine it with the test standards to select the model. You should also pay attention to the withstand voltage of the decoupling capacitor and whether it needs ESD protection.

I used an ST L9779 12v to 5v ldo, which was realized by an external NMOS. The subsequent microcontroller upgrade resulted in insufficient 5v drive capability, so I added another NMOS.

The 5V voltage was found to fluctuate. Finally, the reason was found to be that the MOS gate-level drive resistor 1k was too large and the dynamic adjustment ability was poor, so it was changed to 100r.

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Thanks for sharing

If the driving resistance of the MOS tube is large, the Miller effect occurs because the driving voltage rises very slowly.

100R is a bit big, a few dozen R is enough