NFCのトピックRe: PN7150 - Standby Mode

PN7150 - Standby Mode

adrianpakosinsk — Wed, 17 May 2017 11:35:18 GMT

Hello,

I have a question about standby mode in the PN7150 chip. I have a running example NXP-NCI LPCXpresso example (SW3241) - NXP-NCI_LPC11xx_example on my uC. I would like very low current consumption on my device so I want to use standby mode. Theoretically, it is enabled. Below a snippet of code and send command and response from PN7150.

NxpNci_CORE_STANDBY[]={0x2F, 0x00, 0x01, 0x01}; /* last byte indicates enable/disable */

...

NCI >> 0x2f 0x00 0x01 0x01
NCI << 0x4f 0x00 0x01 0x00

...

I measured current on the oscilloscope. These waveforms show voltage drop on 1 Ohm resistor.

The first graph shows current on listening mode and the second when the card is reading.

As you can see Imax = 223mA. This is a value that is not consistent with the catalog note. I will add that when I disable standby mode (NCI >> 0x2f 0x00 0x01 0x00). The waveforms looked the same, the current has the same value. Why the current is so large? What could be the reason?

Best Regards,

Adrian Pakosinski

Re: PN7150 - Standby Mode

Kan_Li — Fri, 02 Jun 2017 08:28:16 GMT

Hi Adrian,

Would you please specify on which platform you measured the voltage, OM5578 or a custom board? please help to clarify.

Have a great day,
Kan

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Re: PN7150 - Standby Mode

adrianpakosinsk — Fri, 02 Jun 2017 08:41:24 GMT

Hi Kan,

Thank you for your interest. These measurements come from custom board but also I made measurements on OM5578. On OM5578 the charts were similar shape but the voltage was smaller, exactly 120mV when the card is reading.

Thanks,

Adrian

Re: PN7150 - Standby Mode

Kan_Li — Fri, 02 Jun 2017 09:00:50 GMT

Hi Adrian,

I think it would be possibly a hardware design issue, please kindly refer to http://www.nxp.com/documents/application_note/AN11756.pdf for reference.

Hope that helps,

Have a great day,
Kan

Re: PN7150 - Standby Mode

adrianpakosinsk — Fri, 02 Jun 2017 09:15:57 GMT

Thank you for your answer. I read this document and followed the recommendations. Is the current 120mA taken by OM5578 is a normal value? (when the card is reading). Maybe on my custom board is some hardware design issue but I think on OM5578 everything should be fine.

Thanks,

Adrian