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PMP30465: PMP30465

Terry Wu2
Expert 2110 points

Part Number: PMP30465
Other Parts Discussed in Thread: TPS40210, , PMP30491

Hello Sir,

Can I refer this design modify to 5V~20Vin 15Vout@2A ?

If yes, how to decide COMP pin R/C value ?

Many thanks !

  • 0
    TI__Intellectual 2610 points
    Hi Terry,

    At 5V input the current in the inductor goes up by 50%. It looks like it has margin to increase. I will let the designer comment on the feasibility of this request.

    As for the compensation network, TPS40210 is peak current mode control. The output pole is set by the output capacitance and load resistance. The compensation should work as is, but it can be tuned and optimized for 15V/2A.

    More to come...

    Ryan
  • 0 in reply to Ryan Manack
    TI__Intellectual 2770 points

    Hello Terry,
    PMP30465 has been tweaked to high input voltage 80V
    by using pre regulator; you ask for 20V input only...
    Just have a look at my SEPIC PMP30491 using LM25122;
    this ctrl. is able to handle 3V input and by using synchronous
    rectification you'll have a nice efficiency, just see my test report.
    Best regards, Bernd

  • 0 in reply to Bernd Geck
    Expert 2110 points

    Hello Bernd,

    Currently already use TPS40210 SEPIC design .

    Due to Vin supply from car battery 13.5V typ and need to support Vin drop to 5V  and output still keep 15V@2A .

    Base on this condition, would you help to comment below sch ?  TKS !

  • 0 in reply to Terry Wu2
    TI__Intellectual 2770 points
    Hello Terry,
    don't know ESR zero of your design, so please do your type 2 loop compensation as follows:
    1) calculate right half plane zero RHPZ, it's a function of duty cycle, magnetizing inductance and load resistance;
    worst case is at maximum duty cycle - so calculate for lowest input 5V:
    RHPZ sepic = (Vout x (1-d)^2) / (2 x PI x d^2 x L x Iout)
    2) now set your gain for crossover frequency BELOW 1/5 of RHPZ; if your requirements for dynamic performance are minor
    go for Fco of 1/10 of RHPZ, so you will have better gain margin and better phase margin;
    this helps if quality of output electrolytic is poor, means ESR increases at low temperatures.
    3) now set your compensation zero to twice the load pole
    4) now set your compensation pole to 10x Fco; if ESR zero is below 10x Fco set compensation pole to ESR zero;
    That's all and you're done, best regards, Bernd