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Original question:

RF430FRL152H: RF Energy Harvesting

TPS70933EVM-110: RF Energy Harvesting

Eng. Cooper
Prodigy 140 points
Part Number: TPS70933EVM-110
Other Parts Discussed in Thread: BQ25570, , TPS709

Dear TI,

Lately, I have been searching for a device that can harvest the RF waves (frequency range 1 MHz - 2.4GHz) without the need for impedance matching and rectenna phases to power my circuit that has a maximum input current 0.7A, maximum input voltage 5.1V and with an operating voltage of 0.7V. Unfortunately, most of the output I got from those RF energy harvesting devices I think will output less than 0.1A, therefore  I decided to use TPS70933DBV, which will need impedance matching and rectenna stages. That being said, is it possible to draw out 0.7V~5.1V @ 0.7A from TPS70933DBV product? If not, which product from the TI store do you have in mind that can harvest RF waves and output current of minimum 0.7A?

Here is the schematic

  • 0
    TI__Mastermind 23361 points

    Hi Mr. Cooper, 

    We apologized for the delay in response. For some reason, the schematic did not show up. Is it possible for you to reupload it? 

    Regards, 
    Jason

  • 0 in reply to Eng. Cooper
    TI__Expert 6835 points

    Hi Mr. Cooper,

    After reading the post I am a little confused on what you want the regulator to do. Do you need the LDO to harvest the energy from your 1MHz-2.4GHz wave first and then also power the down stream load? Or will there be a separate antenna that will do the harvesting and then you just need to power down stream circuits?

    Do you need this LDO to power the full load at 0.7V at 700mA? This part is only capable of outputting 150mA and cannot output 0.7V. 

    Regards,

    Mark

  • 0 in reply to Mark Sellers
    Prodigy 140 points

    Dear Mark,

    Sorry about that.

    Yes, I would like the LDO to harvest the energy from the RF Wave (1MHz ~ 2.4GHz) first, and then use the output power drawn out from the LDO to power the downstream load, whose parameters are 0.7VDC @ 700mA. I will be using two antennas in this design to double the input power to the LDO, that is why there are two antennas in the input. Since the TPS70933EVM-110 has a maximum output parameter of 150mA, what if I use it to power first BQ25570 before integrating it to my circuit? Then use the output power of BQ25570 to power my circuit. I have seen in the BQ25570 manual that, the maximum input parameters for BQ25570 is 5.1VDC @ 0.1A, which fortunately only requires 0.6VDC to start operating efficiently.

  • 0 in reply to Eng. Cooper
    TI__Expert 6835 points

    Hi Cooper,

    Sorry for the slow response. it does have the potential to work here, but there are a few concerns I have. You are looking to supply 490mW of output power from the BQ25570 device and the maximum power you can source from the TPS70933 is 495mW, so the buck converter will have to be nearly 100% efficient. The other concern i have is that you will need to get the input of the TPS709 to about 5V for it to regulate properly. will your antennas be able to drive enough power to do this?

    Mark

  • 0 in reply to Mark Sellers
    Prodigy 140 points

    Dear Mark,

    I know it may seem not to be feasible but if you take a look at that circuit (TPS70933DBRV design I2C), the circuits' potential of adding more antennas in the input will definitely provide adequate power to sufficiently drive the TPS70933. Although antennas generate AC power, integrating more DC power right after converting the RF AC to DC power at the rectifier by adding more antennas will draw out more power >495mW, which according to my calculations will power the TPS70933 I2C sufficiently.

    If my calculations are not wrong, 2 Antennas will approx. generate ~495mW, hence if I add one more antenna to the circuit, which is very much possible according to the design, the 3 (or more) antennas will generate more than >495mW. Technically, adding antennas that operate under different frequency will increase the pros of my circuit since practically it may cover a wide range of frequency capture operational capabilities, reducing the dependency of having to be in LOS when harvesting RF Energy.