Maximum input voltage of LA/LB of Desfire EV3

[alina]

we have a customer use Desfire EV3, They ask the maximum input voltage of LA/LB , this parameter I did not find in datasheet. Could you help to check ? thanks a lot

[thomas598henry]

Hello @alina,
The maximum input voltage for LA/LB pins on Desfire EV3 isn’t explicitly listed in the datasheet. For precise electrical specs, it's best to contact NXP support directly or refer to their official community thread where similar queries are discussed.

Best Regards,
Thomas Henry

[psvz]

Hi @alina 

Theory goes like this...

page 19 in MIFARE DESFire EV3 contactless multi-application IC gives us I-max of 86mA.

In a resonant LC circuit voltages on L and C are misaligned. I assume the ask comes from the need to assess calibrating capacitor rating, so let's deal with Vc.

VCmax = Imax * XC (capacitive reactance)

XC = 1 / (2 * π * f * C)

Assuming values 13.56MHz and 70pF, VCmax = 14.4V

I don't believe it is possible to guarantee anything here because an external reader outside your control drives the voltage - hence it can't be part of the specs.