Content originally posted in LPCWare by Sergio29 on Sun Dec 07 23:37:10 MST 2014
Hi t9cpu
You are right
Today, always waiting for NXP help and solutions, I think what LPCD function on MFRC630 or CLRC663 NXP Mifare component is virtually unusable for using it in low power with non-rechargeable batteries.
I think it's the only reason to use LPCD function, is'nt it ?
A lot of parameters make it to fail (such has temperature variation)
6 month ago I start working on those problems and today I haven't found a really good solution.
I contact NXP via EBV for this problems 5 months ago with all explanations and I have transmit my schematic and board design with only this answer "All works fine, no one experiencing this problem" !!!!!
You can just verify this problems with the red evaluation board !
Sometimes it detect without card presence
Sometime at 1 cm
Sometime at 2 cms
Sometime there is no more detection
It's changing day to day.
Try to reduce Rxp ans Rxn resistor in your design, I decrease it from 15k Ohm to 10K or 8K for better results
(Always assuming that RXp and RXp does not exceed max level)
But variations of card detection stay here...
What board do you use ?
Can you send to me your documentation if it's your own design board, I will do it too if you want.
If you plan tu use LPCD using non-rechargeable batteries, keep in mind that erronous detection will use 80 to 100 ma on power supply during Request command (40ms) to verify presence of the card !
I have used software solution to resolve this other problem but it's not really the good solution...
Exepted the LPCD function, this component works very fine
Happy to read you
Serge
