Power ManagementのトピックRe: MC33879 initialization voltage abnormality and slow initialization

MC33879 initialization voltage abnormality and slow initialization

zuozuo — Wed, 10 Jun 2026 01:52:06 GMT

After supplying power to mc33879, enable the en pin and connect a 12V power to the D1 pin of mc33879. Without giving the command, measure the voltage at the S1 pin, which is 12.45V, slightly higher than 12V. Is this normal?
Similarly, D1 is connected to a 12V power supply, and S1 is connected to a CAB 500-C current sensor. After I power it on, I control the EN pin high level. According to the manual, after stabilizing at 100us, the command can be issued. However, I need to issue the command 10ms later for the function to be turned on properly because my SPI command has an open/short circuit command detection. The second time I issue the same command every 10ms, the SPI data will display the current channel fault. The third time I issue the same command every 10ms, and the fault will disappear. What's going on?

Re: MC33879 initialization voltage abnormality and slow initialization

db16122 — Wed, 10 Jun 2026 12:20:22 GMT

It seems there are fault for open or short circuit. You may need to double check your schematics with mc33879 application diagram

Does VDD connect with 5V instead of 12V?

Re: MC33879 initialization voltage abnormality and slow initialization

zuozuo — Thu, 11 Jun 2026 06:10:16 GMT

VDD is 5V

Re: MC33879 initialization voltage abnormality and slow initialization

guoweisun — Fri, 12 Jun 2026 00:05:43 GMT

分享一下您的原理图。