NFC IC: Considerations during calibration test setup
Typically, the in-production calibration process consists of four sequential steps after initial configuration:
1) power on device and measure the output current (NFC IC in lighting mode);
2) calculate the duty cycle correction factor;
3) power down device;
4) reprogram the duty cycle (NFC IC in configuration mode).
In the implementation, two topics need to be considered in the concept phase. One is the test time. Since the NFC IC enters the configuration mode only once the Vcc voltage level is reduced close to 0V, after switching off the supply voltage (step 3), the Vcc discharge speed will impact the overall test time. To reduce the test time it is recommended to consider a Vcc discharge circuit while setting up the test.