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RF430cl330h and wireless (inductive) power

Alex Wehmann
Prodigy 50 points
Other Parts Discussed in Thread: TIDA-00217, RF430CL330H

I am developing a product that will include a RF430CL330 as a NFC target for communications, however the other electronics in the target device will require contact-less power, which I aim to supply via an inductive charging field. It is my understanding that the inductive antenna can only input a maximum of 4.1v to the RF430.  Is it possible to isolate the antenna from the chip? Ideally I would like to use both inductive power and NFC at the same time, effectively turning the target device into a higher-power passive NFC tag.

  • 0
    TI__Guru* 91146 points

    yes - this is exactly the approach taken here with this TI Design

    http://www.ti.com/lit/df/tidr853/tidr853.pdf (schematic)

    TI Design (all collateral) ==> http://www.ti.com/tool/TIDA-00217 

    The voltage supplied to your system should be regulated as you might not be able to limit the voltage level seen on the antenna coming from reader side because of any variability to the distance between the reader and the tag antenna and any variability in the coupling factor. So then you can characterize that in your system and then choose either boost, buck or buck/boost IC to achieve your goal. 

    you can also see the concept of the regulator being used in this attachment

    2235.Deriving Voltage and Current from HF RFID_public.pdf

  • 0 in reply to Josh Wyatt
    Prodigy 50 points

    Hi Josh,

    Thanks for the quick reply! While this does solve my problem in most situations, there are some target devices I am developing require higher power than a standard NFC reader can supply.  The higher power target device would require around 50 watts. I have considered using multiple receiver coils (one for NFC and one for inductive power) and adopting the Qi medium power standard (120 watts), but I believe it induces around 12-20 volts, and I am concerned that the RF430CL330H would be destroyed, and as such I would still like to isolate it. I am certain this is possible as there are many smartphones that have both inductive charging and NFC on the market today.

  • 0 in reply to Alex Wehmann
    TI__Mastermind 39170 points

    Alex,

    I beleive you will need to use different coils if you need that much power.  The two coils will be at significantly different resonant frequencies(13.56MHz vs. ~100 - 200kHz), so there should not be much coupling on to the NFC coil.  50W is an awful lot of power to be transmitted wirelessly!  I did find some reference to this in the Q&A below.  Wurth states there is no plan for a 120W class in the Qi standard, but I do not know for sure as Qi is not my expertise.

    http://www.element14.com/community/groups/wireless-power-solution/blog/2014/02/21/qa--practical-implementation-of-wireless-power-webinar

  • 0 in reply to Eddie LaCost
    TI__Guru* 91146 points

    additionally - its illegal to transmit that kind of power @ 13.56MHz 

  • 0 in reply to Josh Wyatt
    Prodigy 50 points

    Thank you, Eddie/Josh!

    We weren't planning on having any radiated power above a few microwatts, very locally. The entire contact-less coupling had a two part RF / magnetic shield that mated before the coil energized. I may continue to research the high power inductive supply, however due to budget, time, and marketing constraints for the product, we will have a LiFePO4 battery pack in the target that will only be activated when needed.  Thank you both very much for your time, it was a pleasure speaking with you. Looking forward to more business with TI in the future!

    Sincerely,

    Alex Wehmann