Further measurements to come, but this is what I have so far.
I have designed a PCB with the TPS55288. The regulator is being used to generate 12V in buck boost mode. It is programmed via a microcontroller.
Some of these boards have been running for weeks with no issues, but sometimes, starting under load the chip will fail.
I have also seen cases where the chip will fail to initialise. When starting the regulator using the enable bit via I2C, the chip will generate a short pulse at the output and then reset all its registers to the defaults almost immediately.
At this stage, the board has only been used at room temperature and driving loads up to 1Amp (Excluding any startup transients).
The input supply has never exceeded 15V and there is a protection device to ensure it never exceeds 16V.
The microcontroller only starts the regulator when the input voltage exceeds 11V and there is a protection device to ensure the entire circuit is not powered below 8 volts.
I have added the webbench simulation that we used.
I also added the schematic and the pcb.
The pcb is a 4 layer board: Top Layer, Ground Plane, Power Plane, Bottom Layer.
The power plane is used for the input supply.
The bottom layer is only used for the I2C bus, enable pin and Gate drive of Q3.
I am aware that the traces to the inductor are very thin and intend to widen them on the next revision, but please advise if you can see other issues with this design.
Please Help!!!
Thanks
