Comparing low power card detection between ST25R210/300/500 and ST25R39xx

[OliM]

Since the 210 reader seems to be cheaper and smaller (in non BGA package) than the 3916b we are currently using, while delivering comparable output power, I am naturally intrigued.  
But the wakeup mode figures don't quite impress, even though it is advertised for situations "where each µA matters".

Wake-up mode for the ST25R300, ST25R500, ST25R501 and ST25R210 - Application note

gives a 75.17 μA figure for 200ms scanning (using 250mA Amplitude)
Wake-up mode for ST25R3916/16B, ST25R3917/17B, ST25R3918, ST25R3919B, and ST25R3920/20B devices - Application note
gives  a 43.74 µA figure for 200ms scanning (using 200mA Amplitude)

Even adjusted for the amplitude difference, that would give >35% more power draw for the 210. Is there a way this is compensated through higher sensitivity, so actually we need less Amplitude on the 210, or should I really expect a regression in low power card detection?

[Ulysses HERNIOSUS · Accepted solution]

Hi,

these two example numbers cannot be really be compared:

• 200mA vs 250mA: depends on application matching / chosen regulator setting (as already discovered by you)
• Tmeas: 25us vs 43.7us: On R210/300/500 it can be easily be adapted between 10.7 and 43.7 (with tagdet_len even up to 61.4us)

Without having done the math in detail I expect with similar Tmeas and similar amplitude also similar power consumption. Compared to ST25R39xx I expect much more sensitivity.

You can even further reduce Tmeas and see if it affects noise floor and thus also sensitivity.

BR, Ulysses