ST25R3916 Discovery Board purchase and design files

[gabriel.neves]

When will ST release the access to buy the new ST25R3916 Discovery Board? And the design files of this board?

[Carlo Corlattoni]

​Hi Gabriel,

Our actual planning to have ST25R3916 Discovery Boards in distribution channel is beginning of Q3/2019.

Regards, Carlo

[gabriel.neves]

Thanks Carlo! We were designing an NFC reader with the 3911B, but now we are designing with the 3916, which seems to be better. So, if you could share with me the design files (schematic and gerbers) of the dev kit would help me a lot. The IC's datasheet still doesn't have much information about the peripherals design, such as the AAT circuit.

I await your comments.

Cheers.

[Carlo Corlattoni]

​Hi Gabriel,

the complete documentation is still under preparation inlcuding appnotes like that for AAT. However, the layout and schematic for ST25R3916 is similar to the ST25R3911B, the minimum system configuration can be seen in Figure 2 of the ST25R3916 datasheet. In case of using SPI interface you have to additionally connect I2C_EN to GND. If you search for ST25R3916-Disco on ST website you can download the firmware.

Regards,

Carlo

[Ktwo]

It's sad because the chip is already on sale on mouser, digikey.. Could you just generate a pdf output of the altium design of the ST25R3916-Disco. I understand it is similar to the 3911B but somehow you do have those files :) so why not share ?

[gabriel.neves]

My main doubt is about the AAT circuit which is a new design, the remaining circuits are quite similar. During this early stages while the information are still not available, for the AAT circuit I'm basing my project in the ST's NFC AAT patent and Murata's solutions for variable capacitors.

[Travis Palmer · Accepted solution]

​Hello Gabriel,

You are absolutly right, the matching circuit of the ST25R3916 is very similar to the matching circuit of the ST25R3911B except the AAT schematic.

Looking at the UM2042 page 13, The ST25R3916-DISCO (MB1414-A) is missing the Trim Capacitor Banks and NFC Forum matching.

For AAT functionallity four Voltage Controlled Capacitors (VCC) have been added. They have put in parallel to the parallel capacitors (e.g. C406 and C408) and series capacitors (C403 and C410).

The VCC is a four pin device, that changes its capacitance between two pins while a DC voltage is applied on another pin. The fourth pin is connected to GND. The typicall tuning range is between 100% =200pF @ control voltage = 0V and 50% = 100pF @ control voltage =3V.

The controll voltage for the series cap can be set in the 26Reg. (0x00h =0V, 0xFF = 3V). The parallel VCC can be set in the 27Reg. This means, that the matching impedance of the antenna can be adjusted by simply updating 26 and 27Reg if the bit AAT_EN is set.

Besides the AN5276 - Antenna design for ST25R3916 which is already available on www.st.com we are working on a AAT and Wake-up appnote. These appnotes will also be released in the next few weeks.

Br Travis

[ben_hw_sw]

Do you have any update about the ST Variable Capacitor 200pF to 100pF (3V) (or similar range) availability and reference (STPTIC-0N200 to be confirmed like described in AN5322 Rev1) ?

• So far on my ST25R3916 prototype boards I'm using 4x Murata LXRW19V201-058 (200pF to 100pF) for AAT-A / AAT-B but the full capacitor range cannot be used as it requires DAC up to 5V and ST25R3916 AAT-A / AAT-B DAC are limited to +3.3V (3.2V in reality with ST25R3916 DAC error from +41mV up to +133mV on full range checked with 121GW multimeter) so capacitor can go from 200pF up to 135pF (instead of 100pF)