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STM32F446 Vcap value

Question asked by martin on Apr 9, 2016
Latest reply on Apr 12, 2016 by John F.
I'm designing a product that uses the STM32F446. The reference manual states that Vcap is increased to 4.7uF (from 2.2uF for the F405) on page 15 and later on page 72 (power supply scheme) it lists 2 x 2.2uF caps on the Vcap pins.

My current design uses a 4.7uF, 6.3V ceramic capacitor in a 0402 package. At 1.2V, the capacitance is approximately 3.5uF. Is this sufficient?

I a previous product with a STM32F405, I had uses a 2.2uF, 4V ceramic capacitor in a 0402 package, which has closer to 1uF capacitance at 1.2V. I never had a problem with this design. I could change the capacitor to 10uF, 10V, 0603, which would have approximately 7uF at 1.2V, but due to space constraints I would like to avoid doing so and I'm not sure if using a higher capacitance than recommended could cause problems.

Any ideas?

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