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TPS7A88: looking at using TPS7A8801 ( 2 channel LDO reg ) for low noise 3V3 and 18V supply from 5V USB

ben biles
Intellectual 860 points
Part Number: TPS7A88

Tool/software:

I am looking at using TPS7A8801RTJT ( 2 channel LDO reg ) for low noise +3V3 and +1V8 supply from +5V USB

I have the idea to feed generated 3V3 from output of channel 1 to input of channel 2 to reduce the voltage

reduction from +5V to +1V8  to +3V3 -> +18V mainly to reduce heat generation.

the power budget is under <200mA on both channels 

The data sheet says each LDO is completely independent.

Apart from potential power sequencing issues I may have with start up on the part its powering , it there a reason why this is a bad idea ?

The main reason for this part selection was space saving and low noise. but maybe there is a better TI option ? 

  • +1
    TI__Genius 13720 points

    Hi Ben,

    As per section 7.3.1 of the datasheet, "If desired, the LDOs can be cascaded to achieve even higher PSRR by connecting the output of one channel to the input of the other channel."

    So yes, it is completely acceptable to connect the 3V3 from OUT1 to IN2.