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RF430FRL152H: RF Energy Harvesting

Eng. Cooper
Prodigy 140 points
Part Number: RF430FRL152H
Other Parts Discussed in Thread: RF430FRL154H, BQ25570

Dear TI,

Currently, I have been conducting research for my thesis project that is supposed to be COMPLETELY POWERED by RF WAVES (in short, it is a battery-less powered circuit powered from harvesting RF waves). The area I am located at has very good frequency capturing capabilities, therefore, the frequency range will be from 1MHz ~ 2.4 GHz. I kinda stumbled upon one of your devices, that is RF430FRL154H and RF430FRL152HCRGER. My question is:-

1. From the RF430FRL152HCRGER pin layout, which pin can I use to connect to the input of my circuit? Should I use the pin 24 (VDDD)?

2. Since pin 3 (VDDSW) is a switch, is it also possible to use it as a boost converter to power my circuit?

3. Is there a TI online simulation that provides services to run simulations on devices like RF430FRL152HCRGER just like the way you have WEBENCH design website to simulate Power topologies? I would really appreciate it a lot if you can also give me more insight, especially better options on how to siphon more voltage out of RF430FRL152HCRGER.

Here is a link to the

Apart from the 3 questions above, I have been thinking of integrating an impedance matching phase for my circuit just after the antenna, but since the RF430FRL152HCRGER does not require impedance matching, can it work with any bandwidth?

My circuit has got the following specs: Vin: 0.3~5VDC, 0.7A maximum & Operating Vin: 0.8VDC

  • 0
    TI__Mastermind 18265 points

    Hello Reagan,

    when looking at the supply current your circuit need (0.7A max) the RF430FRL15x is definite the wrong choice. The voltage you need from the device is VDDH, which is the rectified antenna voltage This pin is specified with nom. 2V @ 100uA. The maximum current you can draw from this device is in the single digit mA range.

    Best regards,

    Helfried

  • 0 in reply to Helfried Vollbrecht
    Prodigy 140 points

    Dear Helfried Vollbrecht,

    Thank you for the feedback.

    With the information you have given me, do you have any other TI product apart from the RF430FRL15x that is suitable to integrate it into my circuit? If the input operating parameters of my circuit are very high (Vin: 0.3~5VDC, 0.7A maximum & Operating Vin: 0.8VDC), I may also use BQ25570 as an intermediate "TO ACT AS A BOOSTER" between the RF Energy harvester and my circuit, since BQ25570 requires only a maximum charge current of 0.1A and with an operating Vin of 0.6V.

  • 0 in reply to Eng. Cooper
    TI__Guru**** 157621 points

    Hello Reagan,

    BQ25570 is designed to extract power from HiZ sources.  It has periodic MPPT sampling.  What is the MPP for the RF device?

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 140 points

    Dear Jeff F,

    I am not an Electrical Engineer, therefore my knowledge about MPP for the RF device is very minimal. Nevertheless, with my experience as an Avionic Engineer (a field that is responsible for all types of aircraft electric and Electronics), I am using your BQ25570 info for my Master's degree project, and if you turn to page 31 of 45 of BQ25570 manual (pdf attached)

    you can see that they are using vibration elements as primary voltage sources. I am sure PZT (a vibration element) and RF devices both produce AC voltage, therefore, that is why I chose BQ25570 for the design and of course, after going through BQ25570 manual I am definite RF can work too. If I am not wrong, the MPP (maximum power point) for my RF device is 3.3 VDC. Since the RF harvester I designed can power an LED (2.9VDC @ 5mA) for a short period, I would like to know whether it is possible to step up the current to a maximum of 0.1A so that it can power the BQ25570?

    NB: As this is not my field of expertise, I am not claiming that this is possible. It's just a thought and would like to know if it is possible and also how to go about it.

  • 0 in reply to Eng. Cooper
    TI__Guru**** 157621 points

    Hi Eng. Cooper,

    The BQ25570 can only accept DC voltage input.  So, any AC source must first be rectified or Zener clamped to prevent the voltage from dropping below zero.  The BQ25570 is not a current multiplier. The BQ25570 boost its input voltage to a higher output voltage in bursts.  Until the voltage on VSTOR=VBAT reaches 1.9V, the charger operates in cold start mode, which is a very inefficient boost converter.  After VSTOR voltage reaches 1.9V, as long as the input capacitor is charged above the MPP setpoint (in your case 3.3V) the charger's boost converter turns on and pulls current from the input capacitor until the voltage falls below the MPP point.  This energy is then dumped onto the storage elements (capacitors and/or a battery) at VSTOR and BAT.  You can then pull more current from the charge storage element.  What is the desired voltage > 3.3V for VSTOR=VBAT?

    Since your MPP is so high, you might consider adding two PFETs, one to short the harvester directly to VSTOR in order to bypass cold start, and then one to connect the harvester to VIN_DC when VSTOR>1.9V, similar to the attached jpg.

    Regards,

    Jeff  

     

  • 0 in reply to Jeff F
    Prodigy 140 points

    Dear Jeff,

    Thank you for the elaborative schematic and positive feedback.

    I will do my research and check which PFET has an efficient low Vf for the design, and according to your question, the desired voltage > 3.3V for VSTOR=VBAT is 5VDC. This is to ensure the continuous working of the circuit at all times during operation. I will design this circuit, test it and then send you the feedback (with graph results of course) just in case someone in the future might have the same query as mine.

    Thank you for your cooperation and stay safe.

  • 0 in reply to Eng. Cooper
    TI__Guru**** 157621 points

    Look forward to hearing your results!

    Regards,

    Jeff