I have a design using the TPS65262-1. My design is identical to the TPS65262 eval board ( http://www.ti.com/tool/tps65262evm-619 )with the exception that the voltage output for the first switch mode regulator is 1.0V instead of 1.2V and there is an additional 680uF tantalum capacitor on this rail in addition to the two 22uF output capacitors (I don't have an eval board here to compare against though). The layout is also almost identical to the eval board.
Under light load everything is fine, but if I load the 1.0V supply with a resistive load, it looks like it is going into current limit at approximatley 300mA instead of the expected 3A. All other outputs work as expected, it is only the first switch mode output that is having this problem.
The input is 12V and remains stable when this happens, and all other outputs remain stable, so this doesn't look like a problem with undervoltage lockout. Also, if I leave the resistive load in place, the regulator output turns on and ramps the voltage up at the soft start rate to the point where it is drawing 300mA, then shuts down for 14ms (hickup time), then re-enables and repeats, so I don't think this is a thermal shutdown and is indeed an over current limit.
I have kept the compensation values from the reference design even though I have additional capacitance on my board. Is there any chance this could cause a problem like this? I don't see any evidence of overshoot or ringing.
Unfortunately, I only have a single board to test with at the moment.
Has anyone seen something similar or have possible ideas?
