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TPS54200: Buck converter with variable current limit?

Part Number: TPS54200

I'd like to use the TPS54200 as a constant-voltage battery charger with variable current limit (microprocessor controlled via the PWM input).  For example, could I set the output voltage to 7V using the FB pin to charge a 6V SLA battery and use the PWM input to limit current?  (current limit would vary with battery size/capacity).

  • Hi David,

         Since TPS54200 is a constant current source LED driver, is it not easy to configure as a constant current source. But we do have a simple circuit that can achieve this constant voltage charger. Can you contact your TI sales or FAE we can introduce this to you through email since we are patenting this.

    Regards

    Sean

  • Thanks for the reply!  If the CV with programmable current limit will work with this, that would be great.  I'm happy to execute am NDA if needed, but It wasn't clear to me how to reach an fae anymore.  Can you point me in the right direction?  Also, will the patent require license fees beyond purchase of the TI component?

  • Hi David,

         "CV with programmable current limit" that maybe not a normal charging process? Since for constant voltage charging process, we control the output voltage is constant and the current is controlled by the internal resistor of the battery and with the charging time. Is that my understanding is right?

    Regards

    Sean

  • Hi Sean,

    CV with current limiting is a very common approach to battery charging.  For most chemistries, when a battery is depleted, the initial charge current drawn may be exceed the damage threshold (generate excessive heat) so it's important for initial current to be limited (and the particular limit depends on the battery chemistry/capacity).  As the battery charges, it draws less current and if the current has been limited the voltage rises.  Depending on the battery chemistry/charging strategy, the battery voltage rises until it reaches a target float voltage and then remains there drawing very little current (or is pulsed or otherwise maintained).

    If you can point me at an FAE who can help with this, I'd be grateful.

    Thanks and regards,
    David

  • Hi David,

    Your previous idea is feasible. However, you need to add circuit of output current sampling and design a proper control loop in MCU to achieve variable output voltage in constant current mode. Otherwise, the output current will not be limited.