Question about a PN7160 operating voltage

[OilCastle]

Hi all.

I have a weird symptom with my PN7160 module.

- Module information
  * NFC 7 Click (MIKROE)

It works usually fine but,
- When VDD is under 3.3V, (e.g., 3.27V) the tag reading is now working well.

- When VDD is over 3.3V, (e.g., 3.34V) the tag reading is working normally.

I tested with some button type tag, my credit card and some mobile devices.
(All cases have a same issue.)

The minimum operating voltage of PN7160 is 3V.

>> Why this happened around 3.3V? not 3V?

>> This kind of symptom is well known? Anyone have some similar history? (I'm new with this solution.)

In my opinion, it's H/W side problem.

If you have any suggestion, (some changes in \\NfcLibrary\inc\Nfc_settings.h, etc.)
please let me know.

Thank you.

[Tomas_Parizek]

Hello @OilCastle ,

The TXLDO check feature is there because of a battery powered systems. If the battery level drops to approx. 3.3V, the PN7160 raises this flag. 

The reason is to avoid a battery undervoltage. But if a user uses a "fixed" power supply e.g. 3.3V, then this feature shall be disabled. 

BR

Tomas 

[KaiLi]

Hello @OilCastle 

The default Setting may have TXLDO check enabled. Try turning off TXLDO check. Please refer to Chapter 11 of UM11495 PN7160 NFC controller for instructions on how to disable TXLDO check.

[OilCastle]

Thank you, KaiLi.

I changed my source code like below.

File: "\\NfcLibrary\inc\Nfc_settings.h"

- Before
uint8_t NxpNci_TVDD_CONF[]={0x20, 0x02, 0x0F, 0x01, 0xA0, 0x0E, 0x0B, 0x11, 0x01, 0x01, 0x01, 0x00, 0x00, 0x00, 0x10, 0x00, 0xD0, 0x0C};

- After
uint8_t NxpNci_TVDD_CONF[]={0x20, 0x02, 0x0F, 0x01, 0xA0, 0x0E, 0x0B, 0x11, 0x01, 0x01, 0x01, 0x00, 0x00, 0x00, 0x10, 0x00, 0x10, 0x0C};

Would you please share me more detail explanation of this phenomenon?

What's the purpose of the TXLDO and why it's default enabled?

I guess most users might choose simple power supply.

Please kindly answer me for our internal issue closing.


Thank you.