NTAG5 Link Energy Harvesting - Supercapacitor

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NTAG5 Link Energy Harvesting - Supercapacitor

NTAG5 Link Energy Harvesting - Supercapacitor

Introduction

NTAG5 offers a powerful energy harvesting feature (up to 30mW). One useful application can be charging the supercapacitor which then might be used as the supply of customer MCU, Sensor, etc. 

 See the typical schematic below: 

Tomas_Parizek_1-1715072033483.png

C1 and C1P are used for the impedance tuning. The antenna is typically tuned at 13.56 MHz-14MHz. 

R1 is used to limit the charging current of the supercapacitor. Its value depends on the selected VOUT voltage, keep in mind that the maximum output current is 12.5 mA. 

E.g. VOUT=2.4V, Icharging=10mA -> R1=240 Ohm

Keep in mind, that if the charging current is too high and/or the amount of the received magnetic field is not high enough, the VOUT may drop. 

D1 should be a low-drop diode e.g. RB520CS30L

Used super cap: CPX3225A752D

Antenna size 

Generally, it is best to attempt to match the tag and the reader antenna geometries for
maximum efficiency. A significant difference between the reader and tag antenna dimensions result in bad communication and energy harvesting performance because of the small coupling factor.

As smartphone NFC antennas can have different dimensions. It might be challenging to design one NFC Tag antenna that will deliver the best performance for multiple smartphones. 

Tomas_Parizek_0-1715079097898.png

The phone's NFC Antenna dimensions are typically between approximately 25 mm vs 20 mm (NFC Forum Poller Class 6) -- 50 mm vs 30 mm (NFC Forum Poller Class 3).

Note: But this might be different e.g., iPhones 

So customers can consider the following form factors of NFC antennas for their NTAG5 Link design: 

For bigger designs (NFC Forum Listener Class 3): 

 
Tomas_Parizek_0-1715086777079.png
For circle NFC Antenna ->Outer diameter is approx. 44 mm 

 

For smaller designs (NFC Forum Listener Class 6): 

Tomas_Parizek_1-1715086801251.png

For circle NFC Antenna ->Outer diameter is approx. 25 mm 

 

 Tomas Parizek 

Customer Application Support 

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Last update:
‎05-07-2024 06:36 AM
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