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TPS65400-Q1: TPS65400 output current boosting

Marco Fogli
Prodigy 90 points
Part Number: TPS65400-Q1
Other Parts Discussed in Thread: TPS65400, TPS544B20, TPS544B25, LM3000, TPS40192

Dear Sirs,

I have developed a module with one TPS65400 to provide 3 output rail for a FPGA board: +1V, +3.3V and 2.5V (buck 1 and buck 2 in shared configuration).

My company would like to upgrade the FPGA size on the old board to improve the signal processing performance: doing so the +1V rail current increase very much, from to actual 8A to 17A, in the worst case.

My first idea was to connect a half-bridge mosfet stage on the buck1 output node, providing the correct driving and the necessary dead-time from hi-side and low-side mosfet.

However, after this first idea, here is my doubt: how the internal regulator could be work (it would be a Current Mode), when the TPS65400 output stage will do not supply the current of the output filter?

Further, I have more questions: Is there is a method to resolve this? Is there a correct schematic approach to do that?

Thank you very much in advance

Marco

  • 0
    TI__Genius 15135 points

    Hi, Marco 

    1. I think your idea is not practical. 

    2. Suggest to use a higher current devices: 

    Integrated power FET: TPS544B20 or TPS544B25. 

    External power FET: TPS40192 or LM3000. 

  • 0
    TI__Genius 15135 points

    Hi, Marco 

    Some comments: 

    1. “My first idea was to connect a half-bridge mosfet stage on the buck1 output node, providing the correct driving and the necessary dead-time from hi-side and low-side mosfet. ”

    How do you provide the correct driving for half-bridge mosfet stage? Would you add external EA and PWM comparator? 

    2. "how the internal regulator could be work (it would be a Current Mode), when the TPS65400 output stage will do not supply the current of the output filter? "

    TPS65400 internal regulator operation is decided by FB voltage, when FB > reference voltage, it will work in PSM mode, turn off the internal high-side and low-side FET. If TPS65400 sees the FB < reference voltage, it will start switching to charge output.