We have a design with a NT3H2111 / 2211 that is using a class 4 antenna coil with a 100 pF capacitor as recommended in application note AN11276, NTAG Antenna Design Guide. The design works great. However, we have found that some batches of the NT3H2111 / 2211 do not work. We get the error "Tag does not support NDEF". If we replace the NT3H2111 / 2211 chip with one from another batch, then it works just fine. We buy almost all of our chips from mouser.com.
We don't know why we are getting these errors. Are you guys having a counterfeit problem with your chips? Did you guys made new changes to your NT3H2111 / 2211 chips? Any help would be greatly appreciated since we are going to start commercially producing our new design, but we need to be sure that there are no problems with the NT3H2111 / 2211 chips. We will be buying several tens of thousands of these chips.