TPS54061: COMP pin wrong connected

Thomas Schabel

Part Number: TPS54061

I use TPS54061 in my design with VIN = 8....45V. We made first prototypes but manufacturer mount COMP caps wrong. In layout pads of these caps are similar also if 90° rotate mount. Unfortunately our assembler has done this. Now I have connection as seen in attached schematic, COMP pin is unconnected. What happens with this wiring?

Thx for support

over 6 years ago

0 JohnTucker over 6 years ago

TI__Guru**** 191445 points

With the COMP pin floating, the circuit will not regulate properly. I think you should plan on re-working those assemblies.

0 Thomas Schabel over 6 years ago in reply to JohnTucker

Prodigy 105 points

John thx for answer. Do you have a more detailed answer for will not regulate properly. Does output ripple increase or VCC accuracy decrease or regulator tend to oscillation. We have potted parts that can not re-work.

Regards Thomas

0 JohnTucker over 6 years ago in reply to Thomas Schabel

TI__Guru**** 191445 points

The COMP pin is the output of the transconductance error amplifier. The COMP pin voltage is an intermediate signal in the control loop. It is roughly proportional to the switch peak current. The RC network from COMP to ground provides the frequency compensation for loop stability. I would expect the circuit to be unstable with COMP floating. The output could vary wildly. Another possibility, the error amplifier could rail out one way or the other and cause the output to either be close to zero or close to VIN. You can give one of the modules a try, but if they cannot be re-worked they are probably scrap.

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TPS54061: COMP pin wrong connected