Internal SMPS efficiency (STM32WLE5) around 60%?

[surumadurum]

Working on a simple LoRA sensor which is powered by a lithium capacitor, I am wondering whether to rely on the internal SMPS or an external buck IC for stepping down voltage to improve efficiency.

My measurements of the internal SMPS indicate a efficiency of around 60% (if I assume a minimal consumption of 8.1mW)

Is this about right or am I missing something?

So it would be quite beneficial to add an external buck IC like the TPS63900 with >90% efficiency and 75nA Iq and step down to around 2V (LoRa in EU868 should still be operational), correct?

(In that case, should I turn off the internal SMPS for both SubGhz and normal operation?)

[STTwo-32]

Hello @surumadurum 

the SMPS usually improve the power efficiency. Is adding another component and enabling/disabling the SMPS will improve or not the Power consumption? For that, I think you should test all cases with the different configurations and use the one that fit your needs.

Best Regards.

STTwo-32