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Recommendations for VCAP1 on LQFP64 packages

CMcGo.1305
Associate

Hello,

I've been looking into using a STM32F722RET6, which comes in the LQFP64 package. This package only has one VCAP pin, and the datasheet states that the capacitor on this pin should have a capacitance of 4.7 uF, and an equivalent series resistance between 0.1 and 0.2 ohms. It seems as though this is the case for any package that lacks the VCAP2 pin. If anyone has had success using one of these packages, would you be able to recommend a capacitor for this application? It seems very few of the ceramic capacitors on DigiKey list their ESR.

2 REPLIES 2
RMcCa
Senior II

I wondered about that myself and settled on an 0805 tantalum. Works fine with multiple f730 boards running.

After some subsequent reading, i believe that an x7r ceramic cap should work as well. You might have to download the cap's data sheet to find the esr. One can lower the esr by using multiple smaller value caps in parallel. ​

CMcGo.1305
Associate

Yeah, I'd been looking into it as well and it seems as though the consensus is that most ceramic capacitors have negligible ESR. I've also seen that a lot of regulators are now designed to always be stable for ceramic capacitors. I think I'll just do a prototype with a ceramic 4.7 uF capacitor and report back.