MFRC522 +MiniPro 3.3V + Adafruit Powerboost

I have this setup where a MinPro 3.3V is interfaced with a Mifare MFRC522 RFID reader. Power is from a 3.7V lipo cell via a Adafruit charger cum booster. ( https://www.adafruit.com/product/1944)

Problem is simple :

When i use the FTDI232 programming interface the MFRC522 reads very well. The Vcc to it is then 2.9V.

But at the same time if I power up from the LiPo cell, it just does not read. The Vcc to it is then 3.2V.

Is the PowerBoost module oscillator messing up things for the MFRC522 ?? Any other ideas ??

Is the PowerBoost module oscillator messing up things for the MFRC522

Sounds like it. Also the supply is a bit high, regulate it to 3V3.

Schematic please.

Grumpy_Mike:
Sounds like it. Also the supply is a bit high, regulate it to 3V3.

Schematic please.

RFID_TX UNIT.PNG

Thanks for the schematic.

I would try some largeish capacitors 47uF or larger on the Vcc to the RFID reader, and maybe a 0.1uF in parallel with it.

Grumpy_Mike: Thanks for the schematic.

I would try some largeish capacitors 47uF or larger on the Vcc to the RFID reader, and maybe a 0.1uF in parallel with it.

The power supply was the issue. As you suggested I tried a available 100uF and the problem is solved. Possibly the RFID was drawing more than the LiPo cell can supply in a short burst.

Thanks so much ! Its worth a Karma !!