TPS40200: TPS40200 current limit issue

Brad Perry

Part Number: TPS40200

Tool/software:

Using the TPS40200 in a 50V input, +5V configuration. Initially was tripping the common mode aspect of I sense pin. Connected small ceramic from pin 5 to 8 and that was solved. Now have an improved layout with this added and the part trips into over current with any load at all, other than no load. The mentioned cap is mounted very close to pins, right next to IC. Removed current sense from the Isense pin and it works, so it seems my new issue is not common mode.

over 1 year ago

0 Ridge Lahti over 1 year ago

TI__Mastermind 22260 points

Hello,

The resistance you have in the Isns is 100ohms. This would set the current limit threshold very very low which is likely why the overcurrent protection is tripping right away. It does not look like you are using the scaling resistors, so I recommend a 0ohm resistor on R35. Shorting R35 would make R34 the current sensing resistance and increase the current limit to 2A.

Best regards,

Ridge

0 Brad Perry over 1 year ago in reply to Ridge Lahti

Prodigy 20 points

The sense R is ,05 ohms. The 100 and 100pf are a filter to the sense signal, unless I have them connected wrong.

0 Ridge Lahti over 1 year ago in reply to Brad Perry

TI__Mastermind 22260 points

Hello,

Please remove the performance capacitor and short out the filter resistance to see if that helps improve the performance.

Also, please share the PCB layout with us.

Best regards,

Ridge

0 Ridge Lahti over 1 year ago in reply to Ridge Lahti

TI__Mastermind 22260 points

Hello,

Since we have not heard from you in a while I will be closing this thread. If you have more questions, you can re-open this thread by replying or create a new thread.

Best regards,

Ridge

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TPS40200: TPS40200 current limit issue