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the output of REF3225 IS 2.52 or 2.6v

feng liu
Intellectual 295 points
Other Parts Discussed in Thread: REF3225, REF3425, TPS63002

the output of ref3225 is wrong ,the input voltage is 5v(VCC3),but yesterday the output of ref3225 is 2.6v,today the output of ref3225 is2.52v,please help me?

  • 0
    Intellectual 295 points
    Furthermore，in the before version of our PCB,we use the two layers,we get the stable voltage output(2.5v),but now we change to a four layers board with more internal electrical layers,however we get the voltage output of REF3225(2.52V or 2.6v),in the two both versions,the schematics are the same,the only difference is the pcb layers.
  • 0 in reply to feng liu
    TI__Mastermind 19550 points

    Hi Liufeng28,

    The REF3225 is sensitive to startup conditions. This can be seen on pg 9 of the REF3225 datasheet. One solution is to add a RC filter like in the section below.

    My recommendation is to use the REF3425. The REF3425 is P2P with the REF3225 and it has improved specifications and does not have input voltage ramp sensitivity.

    -Marcoo Z

  • 0 in reply to Marcoo Z
    Intellectual 295 points
    sorry,the last pcb board(double layers board),we use the schematic of the figure 23,but the output of REF3225 is not right,so according to your suggestion,the RC filter will be removed,and then the output of REF3225 is right,however this time we use the four layers(include two internal electrical layers),the schematic is the same as the last version(no rc filter),but the the output of REF3225 is not right
  • 0 in reply to feng liu
    TI__Mastermind 19550 points

    Hi Liufeng28,

    We had a similar thread recently here that can give you more details.

    Do you have any type of slow supply voltage ramp up or current limiting on the supply voltage?

    -Marcoo Z

  • 0 in reply to Marcoo Z
    Intellectual 295 points
    yes,when we get the voltage (5v)from the tps63002,we need PPTC to protect the components，and then the power after the PPTC will supply the REF3225
  • 0 in reply to feng liu
    TI__Mastermind 19550 points
    Hi liufeng28,

    That might the cause of the problem, the REF3225 is sensitive to slow ramp Vin. I have had better luck with faster ramp rates. Sometimes issues arise if the current is being limited. The REF3425 will solve all the problems you are facing with the REF3225.

    -Marcoo Z