NTP53321G0JHKZ: Maximize Energy Harvesting

[Sotax]

Hi

I will use the IC NTP53321G0JHKZ to communicate and supply a small sensor circuit. Both NFC coils are in a stable, mechanical locked position and in short range (approx. 2.0mm). So the coupling is very strong and always the same. My problem is, that I have to harvest energy as much as possible trough the communication to supply my sensor circuit (supply voltage is 2.8V). When I look at the graph in the NXP application note

AN12365: NTAG 5 - How to use energy harvesting: Figure 2. Current vs. Load vs. H field

and convert the high field graphs from "current vs. field strengh" to "power vs. field strengh" (see attachment), I see that at very high field strenghts that the amount of power is the approx. same for 2.4V and 3.0V supply. I need for my circuit 2.8V supply, so my question is:

What option do you reccomand me when I want maximize the output power of the NTP53321G0JHKZ?

Option A: Choose 2.4V output and boost the voltage to 2.8V (with an external boost converter with high efficency at small load currents).

Option B: Choose 3.0V output and buck the voltage to 2.8V (with an external buck converter with high efficency at small load currents).

What kind of voltage regulator is build inside the NTP53321G0JHKZ? Is there some kind of LDO inside and the voltage that I don't use will get burnt?

Thank you in advance
Raphael

[Sotax]

Hallo Julian

It helps a little bit, thank you.

Best regards

Raphael

[Julián_AragónM]

Hi @Sotax,

Option B is a simpler and better solution, since a buck converter only cuts voltage and displays better efficiency, the calculations and construction results easier, otherwise, boosting the voltage involves more variables and complicates the issue.

There is no LDO regulator, although in the datasheet of the device, on chapter 8.5 (Energy harvesting), there are some insights on configuring energy harvesting, as well as an example circuit;

Since this device does not support any LDO, there are no recommendations for voltage regulating, I would suggest looking externally for basic calculations of buck converter's power stage, and other different guidelines. 

I hope you find this helpful!

Best regards, Julian