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TPS51362 V5 Input

PingL
Prodigy 170 points
Other Parts Discussed in Thread: TPS51362, TPS53353

Anyone know TPS51362 Pin 18 V5 supply current requirement.

From datasheet Page 4, mention current usage with operation in 'No Load', how about this device under full load?

That 5V input for internal analog circuits & gate driver, so gate driver between normal operation at 800KHz switching & discontinuous mode at light load should be different.

  • 0
    TI__Guru**** 191445 points

    Both of the first two specifications are for switching conditions, 100 (low power mode) and 560 uA (normal mode).  The 1 uA spec is for EN=0 (not switching).  I can look to see if there is additional data for it, but we probably don't have that broken out.

  • 0 in reply to JohnTucker
    Prodigy 170 points

    Thank for your reply, John.

    May be the 'No Load' from specification make me confuse.

    From my understanding, this device have two operations mode which dependent on load current.

    (800KHz switching in normal operations, Discontinuous Mode for light-load)

    Does 'No Load' means this device enabled and operated at Discontinuous Mode?

    How about V5 current requiremnet on operating at 800KHz swithcing with 10A output loading?

  • 0 in reply to PingL
    TI__Guru**** 191445 points

    Under no load condition, the device will always be in DCM and additionally, there will be pulse skipping (essentially, the TPS51362 will operate at a much lower switching frequency.  Compare datasheet figures 11, 12 and 13.  I'll see if we have any data available for VIN at 10A output.

  • 0 in reply to JohnTucker
    Prodigy 170 points

    Look forward your further data input. Thanks!

    The V5 input is for gate driver and current consumption is also dependent on swithcing frequency. So I suppost V5 will consume more current at 800KHz than at pulse skipping (low frequency). But don't know how large will be. 

     

  • 0
    TI__Prodigy 310 points

    PingL said:

    Anyone know TPS51362 Pin 18 V5 supply current requirement.

    From datasheet Page 4, mention current usage with operation in 'No Load', how about this device under full load?

    That 5V input for internal analog circuits & gate driver, so gate driver between normal operation at 800KHz switching & discontinuous mode at light load should be different.

    For nor-ULQ mode (LP#=hi or float), it's about 13mA for full load condition (VIN=7.4V, Vout=1.05V, Iout=10A), while for ULQ mode, it will 460uA less than that.

  • 0 in reply to Osial Ou
    Prodigy 170 points

    Osial, thanks for your value input.

    Actuall my platform only does 15mA 5V budget suppling to this V5 pin, operation condition will be VIN=10~12V, Vout 1V35/1V5/1V8 selectable, Iout 8~10A

    Could you advice is it danger with 15mA 5V budget on above operation condition? 

  • 0 in reply to PingL
    TI__Prodigy 310 points

    Yes, it's danger.

    I'm not sure where the 5V/15mA comes from, however, to keep 20mA budget is needed for this device.

  • 0 in reply to Osial Ou
    Prodigy 170 points

    Oh, here is more details on power circuitry.

    We adopt 1 pcs of TPS53353 (10~12V to 1V @15A), this device does LDO 5V output @ 30mA max.

    And adopt 2pcs of TPS51362 (10~12V to 1V8 & 1V35/1V5 @ 8A).

    At this platofrm, there are no other 5V source, if that is danger, I should add 12V to 5V LDO to serve TPS51362.

    Thanks for your time on this evaluation. 

  • 0 in reply to PingL
    TI__Prodigy 310 points

    You's better to have a 12V to 5V LDO.

    For TPS53353's 5V LDO, it need to serve TPS53353 + 2 X TPS51362. The current is not enough.

  • 0 in reply to Osial Ou
    Prodigy 170 points

    Thanks for your evaluation.

    I will add LP2951-50 (5V 100mA) to supply both TPS51362 V5 pin, hope that's enough on full load.