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TPS65320C-Q1: I(ldo_out) under V(vin)=3.3V

hideyuki sakai
Mastermind 6250 points
Part Number: TPS65320C-Q1

Dear, Sir. 

I am considering to apply TPS65320C-Q1 for dual supply 3.3V & 1.8V. 

3.3V DCDC output will use as input VIN_LDO and it outputs 1.8V. 

I am expecting 1.8V/200mA. 

The other side, 19 page on the datasheet, I(ldo_out) will decrease when

V(vin) is less than 4V. 

I would like to know I(ldo_out) = 200mA is possible when V(vin) = 3.3V. 

Please give your advice. 

Best Regards, 

H. Sakai

  • 0
    TI__Genius 9615 points
    Hideyuki-san,
    The capability of the part to drive the output load depends on various factors that we/the part can not influence like temperature, capacitive load, loadsteps and and acceptable response to those.
    The capability needs to be validated on the customers system to ensure the part can drive it.
    I will test on EVM tomorrow to give an indication if it seems reasonable, but it remains customers responsibility to validate it in his system.
    Best regards,
    Frank
  • 0 in reply to Frank Dehmelt
    Mastermind 6250 points

    Dear, Frank-san. 

    Thank you for your advice and help. 

    I understand they must have the responsibility to validate. 

    Your results will be quite useful and valuable indication for customer's judgement

    at the first step. It will become the pretty good reference. 

    Please let me know your results, later. 

    Best Regards, 

    H. Sakai

  • 0 in reply to hideyuki sakai
    TI__Genius 9615 points

    Sakai-san,

    I did some LIMITED testing on EVM:

    I configured the LDO-output to 1.8V and supplied VIN_LDO from a 3.3V-power-supply to eliminate any impact from the buck-regulator. VIN was supplied with 12V.

    The LDO-output maintained 1.79V for 280mA output (higher than the desired 200mA output). I also applied heat (~125°C IC-surface temperature) and the output voltage dropped by ~50mV to 1.785V (which is still less than 1% variance.

    Thus, it looks promising, that the part can maintain 200mA output at 3.3V in, 1.8V out.

    However:
    I tested one unit only
    I only measured steady state, i.e. did not apply any load-steps (neither to the LDO nor to the buck, where buck-output would affect VIN_LDO in customers configuration)
    I heated the surface and self-heating due to losses of the LDO are included, but no self-heating due to buck-operation (buck was enabled, but not loaded)

    Consequently, it remains customers responsibility to validate the performance under the desired conditions in their actual design, covering all potential (worst) use cases.

    Best regards,

    Frank