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Original question:

BQ24650: USB-C battery charging compatibility

BQ24650: 9 V DC wall adapter power source with Solar input

Ibrahim Qasim
Intellectual 680 points
Part Number: BQ24650

Hello,

I asked a question a while back about using a USB-C to power my BQ24650 charging solution which was not the most practical due to the 5 V I am inputting as a power source as opposed to the 6.3 MPP voltage found on my Solar panel. This would have resulted in a decrease of the MPPSET regulation voltage to 0.954 V, the topic can be found here:  .

I was looking at possibly providing a backup wall outlet 9 V DC wall adapter to be plugged in at Vin before D1 and D2 and have both power sources separated by a mechanical slide switch to switch between solar panel and wall outlet charging. Here is the schematic to better understand what is discussed: 

The MPPSET will now be 1.717 V (not 1.2 V)  due to this. So will it be sufficient or feasible to connect a two-way switch leading to either the solar panel or wall adapter sources to Vin before D1 and D2 found above??

Thank you,

Ibrahim

 

  • 0
    TI__Mastermind 24075 points

    Hi Ibrahim,

       Yes, this is feasible. When using a DC supply in conjunction with a solar panel, the key is to have the DC power supply voltage higher than the MPPSET 1.2V regulation point. Alternatively if OCV of solar panel is < DC adapter voltage, you could just use a simple diode OR configuration at the input side, so that wall outlet is always preferred when connected.

  • 0 in reply to Kedar Manishankar
    Intellectual 680 points

    Hello Kedar,

    I'm glad to hear that! As for the diode configuration, are you suggesting I implement something like this at the top left side of my schematic??

    Having 9 V for VDC and 7.4 V OCV would mean that no matter the solar exposure on the PV, the input of my design will always be VDC correct??

    Thanks for your help!