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TPS4811-Q1: TPS4811-Q1 short circuit protection

Meori Mizrahi
Prodigy 40 points
Part Number: TPS4811-Q1

Tool/software:

Hi team 

we are using the TPS48110-Q1 in our new board ,i noticed that the equation for calculate Riscp :

is not correct (or i  just missed something ):

i want that this driver will protect over current at ~ 8A and for that i used 300K  as Riwrn 

Also, i want that this driver will cut the current at ~ 22A ( short circuit protection) i used the above equation and get value of 100 ohm for Riscp ( i use 500u ohm resistor as Rsns) 

but actually the driver cut the current ( short circuit protection)  at ~ 12A 

when i used the excel sheet design calculator i got failure 

please advise 

  • 0
    TI__Expert 8570 points

    Hi Meori,

    Can you send over a schematic for review? 

    Firstly, I notice that your RSNS i snot ideal for the range of current you are testing. Both your Isc and Ioc put your V_WRN < 25mV. This could make your more susceptible to noise

    Secondly, typically when I see this you are experiencing a false trip due to noise. You can add a capacitor between ISCP and CS- to help eliminate this. As well as increase your RSNS value so the V_SNS_WRN is in a better range. If you already have this capacitor try increasing it to 10nF or 100nF. 

    Thanks, 

    Sarah