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TPS5430: One TPS5430 for two output voltages?

John Ackermann
Prodigy 80 points
Part Number: TPS5430

Is it possible to have one TPS5430 configuration that could be set via the Vsense resistors to either 5V or 18V output, assuming a 24V input?  When I run Webench the designs are different, mainly requiring larger Cin and L for the higher output voltage, and larger Cout for the lower voltage.

Would it be feasible to use the larger values (e.g., Cin and L calculated for 18 Vout, Cout calculated for 5 Vout)?  Absolute efficiency isn't critical for my application, though low ripple output is important.  And BOM cost isn't really an issue, either.  Is a compromise like this feasible, or should i just run two separate BOMs?

Also, another question -- I can't find in the datasheet either a maximum Vout, or a dropout voltage (e.g., how much does Vin have to exceed Vout)?  Do those specs exist?  From playing with the designer it looks like at least at the higher Vout, about 4 volts of headroom is required.

Thanks!

John

  • 0
    TI__Genius 10655 points

    Hi John,

    I'm a little confused what you're trying to do.

    Is your goal to be able to dynamically change the output voltage while the converter is operating?

    In terms of the dropout voltage spec, see Figures 7 and 8 in the datasheet. These give the minimum duty ratio and minimum on time over temperature. This can be used to estimate the amount of headroom required. 

    Regards,

    Harrison Overturf