ST25R3916B abnormal power consumption in the wakeup mode

[ShimiaoWang]

I am testing power consumption. The hardware is using nucleo-L476 and X-NUCLEO-NFC08A1, and the software is using the NFC06A1_PollingTagDetect routine from X-CUBE-NFC6. The test revealed that the average power consumption was 180 uA when entering the wakeup. I was using a 3.3V power supply. The minimum current is 40 uA.

I'm not sure how to make the necessary modifications to achieve the description in AN5320.

 

[Brian TIDAL]

Hi,

The typical value of the supply current in Ready mode (I_RD) in the datasheet is measured with the following configuration for VDD = 3.3 V:

• Register 00h to 07h (no clock on MCU_CLK)
• Register 01h to C0h (3 V supply mode, VDD_D disabled)
• Register 02h to 80h (en = 1)
• Register 2Ch to D8h (3.0 V regulator)

See footnote 6 in table 125 of the datasheet.

The configuration used in the X-CUBE-NFC6 firmware is defined in analogConfigTbl_NFC08A1.c (CHIP_INIT section) and uses regulated voltages defined by the result of the Adjust Regulators command, AAT, and a pull-down on SPI. The value of the supply current in Ready mode I_RD is therefore different.

Rgds

BT

[ShimiaoWang]

Hi

 Thank you for your reply.

Based on the register configuration in the data manual, the current under this configuration is over 40 microamperes. Is there any hardware modification required?

 

 

[Ulysses HERNIOSUS]

Hi ShimiaoWang,

I think you are running into issues due to the varicaps being mounted on the board. The issue will happen no matter which value being output on AAT_A and AAT_B. 

To remove this current you can:

1. Remove the varicaps and compensate by increasing the normal caps
2. Set driver to high resistance (d_res=0xf), e.g. write register 28h to 0x0f.

BR, Ulysses