Low power design for ST25R3911B , getting error while operating the IC at 2.8V

[vaibh_p]

Hi , we have made the custom PCB for ST25R3911B with AVR AtMega328P Controller.

The board works totally fine when runs at 3V3.

But for low power design , when ever we try to power up the board on 2.8V , the controller resets.

On debugging we have found the problem in RFAL Library at the function rfalCalibrate() as described below:

1. Adjust the regulators so that Antenna Calibrate has better Regulator values */   

  st25r3911AdjustRegulators( &resValue );

--This works great

2. st25r3911CalibrateAntenna( (uint8_t*) &resValue );

--This also works

3. st25r3911AdjustRegulators( &resValue );

On call to this function the code gets stucked up

What am I missing here?

[Travis Palmer]

Hello vaibh_p,

"But for low power design , when ever we try to power up the board on 2.8V , the controller resets."

Does this mean, the MCU goes in reset mode?

During the mentioned functions, the ST25R3911B turns on its drivers. One possibility could be, that due to the power consumption of the ST25R3911B in this stage, the power supply drops and the MCU enters POR mode.

I would recommend to monitor the supply voltage of the controller. Even a short drop of VDD could trigger the reset of the MCU.

I cannot imagine any other case where the ST25R3911B could cause a reset of the MCU, especially if the design is working at 3.3V.

br Travis

[vaibh_p]

Thanks Travis Palmer , I will check for that.