I'm planning to use two 3.3V LDOs to supply power for two MCUs, one is STM32, one is ESP-12. Input power of these two LDOs come from one SMPS module 5V, 3W (HLK-PM01). The reason for two seperate LDOs: I'm using STM32's ADC and I think separate power supply with ESP will make ADC more accurate. Another reason is there is a distance between HLK-PM01 and ESP, trace length almost 25mm. STM and ESP communicate through UART and both using same I2C F-Ram Memory IC, STM reads ADC, calculates something and save to Memory IC. Then ESP reads data from Memory IC and post to server. All same ground. LDO is RT9013 Datasheet.
So is it possible and working? Or it is a overkill?
Thanks very much
Best Answer
Yes, it will work, as long as both devices share the same ground I don't see any reason why there should arise a problem. But I don't see the any reason to do it this way either. It will be no problem to connect both MCUs to the same regulator. Just make sure to have good filtering for the analog supply of the STM. If you check the STM documents they explain very detailed what should be done to achieve clean input voltages for analog supply and reference: Put an RC-Filter in front of the input of the analog supply or even use a ferrite bead. This will attenuate switching noise from the MCUs and the SMPS.