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TPS40210 pin 3 En/Dis always has the noise when the output attached with a battery load.

xin yang2
Prodigy 40 points
Other Parts Discussed in Thread: TPS40210

Hi all,

I have question about the TPS40210 application. I tried to use it to boost the input 12V to 16V with the ability to control En/Disable pin 3.

Now I found out there are always noises on the Pin 3 and pin 4 that causes my board output dropped from 16V to 11V. Top image shows the input of Pin4 COMP pin. And next image shows the noise input of Pin 3. I tried to tight the Pin 3 directly to ground. But the board doesn't work after tight the pin 3 to GND.

PLease help me to find out this issue.

Thanks.

  • 0
    Prodigy 40 points

    I don't know why my first image missed on my previous post. Here is another image to show the noise input of Pin 4.

  • 0 in reply to xin yang2
    TI__Mastermind 35165 points

    Hi Xin,

    Does the TPS40210 output anything when the EN/DIS pin is held to ground? I think it will be easiest to debug this first by removing the external control circuit from the factors. Some signals to start out with are the gate of the FET and the drain of the FET.

    After looking at the schematic, I have some doubts on C11. Can you share the part number and maybe some calculations you used to select it? In a SEPIC topology this capacitor must be rated for a relatively high RMS current.

    Lastly what load current is the design being tested at? You also mentioned a 12V input to 16V output. Is there any particular reason a SEPIC topology was used over a Boost topology?

    Best Regards,
    Anthony 

  • 0 in reply to Anthony F
    Prodigy 40 points

    The TPS40210 didn't output anything when tighted to Ground.

    The C11 part number is P5575-ND from Digikey.

    The output voltage is only 11V instead of 16V.

  • 0 in reply to xin yang2
    Prodigy 40 points

    can anybody look at the noise scope and tell me what kind of noise they are?

    THanks

    xinsong

  • 0 in reply to xin yang2
    TI__Mastermind 35165 points

    Hi Xin,

    By output, I mean can anything be seen at the SS or GDRV pins? It is unusual the TPS40210 does nothing with pin 3 connected GND, which forces the device to be enabled, yet it has the irregular signals if it is not connected to GND. Can you also try disconnecting all of the circuitry connected to pin 3 then connect it to GND?

    Anthony