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LTC4120 Wireless Power Receiver Constant Voltage mode

Hi! 

I'm developing a wireless powered system WITHOUT battery. Therefore, I need a constant voltage (and not constant current) node at the LTC4120 wireless power receiver output. I'm using the evaluation board, which features the LTC4125 as transmitter IC and the LTC4120 as receiver IC. Up to now, I got only constant-voltage/constant-current, and I was wondering if there's any way to convert this kind of supply in the constant-voltage one I need. I don't know if there's any pin I should tune inside the LTC4120 (I couldn't find anything like that in the datasheet) or if I have to add an external circuit. So, can you suggest me a solution? Is there any external circuit or different receiver IC I should use? Thanks!

  • Hi DvdOne, 

    Unfortunately LTC4120 does not support this constant voltage solution. The only way to get a semi-constant voltage is to use a really large cap on BAT pin to replace the battery. The LTC4124 has a VCC pin that is voltage regulated. You can connect a 10uF on BAT on LTC4124 and you will observe around 5V on LTC4124 VCC. How much current do you need for your solution ? What is your load range on your receiver side ? Will there be any fast transient on the load side ? 

    Thanks,

    Wenwei. 

  • Hi Wenwei,

    Thanks for your answer.

    I would need 200mA, more or less, as output current at 5V. I tried using a full bridge rectifier instead of the LTC receiver module, and the circuit is behaving well. Do you think this could be a good solution? Or it would be better to use the LTC4124 as you suggested? (There won't be any fast transient on the load side)

    P.S: I’m transmitting with the LTC4125.

     

    Thank you and have a great day,

    Davide