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Solar charger circuit for 6 to 24V solar panel to get 5V output and have a lithium battery backup.

Emilija Zukauskaite
Expert 1100 points
Other Parts Discussed in Thread: TIDA-00120, TIDA-01556, BQ24650

Hi. I would like some advice on solar charger circuits. We need to be able to use 6V, 12V or even 24V solar panel and get 5V. We also need to use a lithium battery backup. Can you please recommend the design?

  • 0
    TI__Expert 5130 points
    Emilija, hello and thank you for your interest in Texas Instruments. We don't have a TI Design available that meets what you are looking for. At present we only have a few solar charge circuits available in our TIDA-01556 and our TIDA-00120 to name a few. I'll forward this to our Grid Infrastructure team to see if they can make some suggestions that may be of assistance.

    Best Regards,
    J. Fullilove
  • 0 in reply to JohnFullilove
    Expert 1100 points

    Hi John,

    Thanks for your reply.

    I'm thinking to use BQ24650 part this accepts the input up to 28V to charge 3.7V battery and use a step up to 5V. A problem I have is that BQ24650 has got a battery detection circuit and it will not work if battery is not connected. I need it to work without a battery. I found that there is a way to stop the battery detection function by adding the Schottky diode between SRN and the resistor feedback. Would that work? What are the negatives of turning the battery detection function off?

    Or another idea is to detect the battery not present and turn on the main power path going to the step down regulator to 5V and supply power from there. Can BQ24650 set a logic once it detects that battery is not present? 

    Regards,

    Emilija

  • 0 in reply to Emilija Zukauskaite
    TI__Guru 57651 points

    Emilija,

    The BQ24650 internal battery detection circuitry can't be disabled. But the battery detection function will not work if the total capacitance connected to VBAT (charger output) is bigger than Cmax. And BQ24650 does not send out any logic for battery detection results.

    Thanks,

    Ning.

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