Is the NFC controller on NHS3152 rated for a maximum of 1.875V?

[acuom]

In various threads and in my own experiments, I have noticed that the maximum voltage on an NHS3152 when powered only over NFC is about 1.8V. Is this a physical limitation of the board or is it possible to provide a higher voltage (around the typical operating value for the IC) by designing a custom reader/well coupled antenna?

Also, are there any maximum number of restart cycles for the lifetime of the NFC controller on NHS3152? A couple of my boards are unable to be powered over NFC but can still transmit data over NFC when connected to a computer over USB.

Would be immensely grateful for any help!

[driesmoors · Accepted solution]

Hi,

The NFC controller of the NHS3100 and the NHS3152 IC will provide 1.85V to the chip. There is no possibility to increase this: the excess energy harvested will be dissipated as heat by the IC. If you need a higher voltage, you must generate this externally and supply this via the VDD BAT pin.

There is no defined limit on the number of restart cycles. If a board is unable to be passively powered over NFC, but runs fine when the PCB get power via the SWD lines from your debugger board connected to the PC, it may very well be that the firmware enables too much HW blocks causing a voltage drop that cannot be overcome when running passively.

Can you check:

• Your clock frequency: try to lower this
• Your pin configuration: do they have a pull, and do they have the correct pull (up or down)?
• Your PCB: are there external caps attached? These are best loaded slowly, to avoid too severe voltage drops.

Kind regards,
Dries.