Does the LPCD mode from CLRC663 really work? Unable to find single working real-life example

[marlowlannister]

Hi all,

I am trying to assess wether it is possible to build a battery powered nfc reader, based on the nxp clrc663. The LPCD mode seems to be great, with average consumption around 10/20 uA.

However, I can't find a single real-life example showing this lpcd mode working. In fact, it is like no one is using this part at all, let alone with the lpcd mode.

Did anyone here already tried the LPCD? Does it work? Is it reliable? What detection range did you get?

Thank you for your help!

Marlow

[markschwab]

I have it working.  The trigger distance is about half the read distance depending on the settings.  I think there was a bug with the firmware where the lpcd routine would start and instantly trigger.

[marlowlannister]

Dear Mark,

Thank you very much for your answer.

Did you encounter any issue during your hardware or software development regarding the LPCD mode (except for the firmware bug that you mentioned)?

Would you recommend this chip for a low power battery powered reader?

Thank you for your help!

Marlow

[markschwab]

On the hardware side the biggest issue was with tuning.  The tuning has to be done correctly or the distance detected is not that great.  Match the impedance to around 40 ohms and you will be fine.  The oscillator has to oscillate close to 13.56*2 as possible.  If it doesn't then the match will not work at that frequency.  If you design the reader antenna with a higher Q then it will detect further away.  If the Q is too high it won't be able to read the tags.  My Q is at around 10. 

I had a lot of software issues because the libraries NXP provide were only for an ARM processor.  I am using a 8051 processor so I had to change a lot of register settings and timing issues came up etc etc.

Yes, I would recommend it.  I use a 90mA battery and it runs for a couple weeks with my setup.  I don't think any other chip can do that.

[marlowlannister]

Dear Mark,

Thank you very much for your answer.

I will definitely try this part out thanks to you.

I plan to use a CR2032 battery and activate the lpcd feature 2 or 3 hours a day on average, hoping to get a few months of battery life.

Thanks again for your kind help.

Marlow

[markschwab]

You'd have to use a large capacitor for instantaneous power the chip uses

up to 250 ma for a few microseconds in lpcd. The cr2032 can supply 30 ma or

so

On Tue, Feb 14, 2017 at 3:24 PM marlowlannister <[email protected]>