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TPS3808-Q1: if my sense V is around 5.8V,the reset pin will output high-low alternately,but when I add a 470nf at the sense pin,it wil ok 。So,can I add a 470nf?

Part Number: TPS3808-Q1
Other Parts Discussed in Thread: TPS3808

Tool/software:

if my sense V is around 5.8V,the reset pin will output  high-low alternately,but when I add a 470nf at the sense pin,it wil ok。So,can I add a 470nf?

  • Hi, 

    Thanks for your question.

    Can you please first  provide the scope picture zooms in the VDD voltage, and SENSE voltage when RESET pin asserts (becomes low)? 

    This way I can better assist you in your inquiry.

    Thanks,

    Sila Atalar 

  • Please see the annex,thanks

  •  I add a 470nf at the sense pin,the wave form like this

  • Hi, 

    Yes I was expecting your sense signal might have some sort of noise. For specifically noisy appellations, it's okay to have a small cap at sense pin. 

    Best,

    Sila Atalar

  • For TPS3808,the reset osignal used to control SOC power on/off,when sense voltage under threshold level,SOC power will off,so the system loading will down,then the sense pin voltage will up slightly,this will cause reset change to high level,SOC power up again,but SOC power up cause system loading up,sense pin voltage down,then reset pin output low level,SOC power up , this scenario would repeat , this is the noise where come from .

    For this scenario ,can I add a 470nf to restrain noise ? 

  • Hi,

    For this application case, I don't see any issue having a small cap there. It seems like you need one to smoothen the noise so that it will stop the sense voltage to go below than the threshold voltage. 

    Hope this helps!

    Best,

    Sila