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TPS61178EVM-792: Output voltage drops to zero periodically.

Part Number: TPS61178EVM-792

I am currently making modifications to an evaluation board to boost a 3.6V Li-Ion battery up to 14V-15V. We want an output current of 2A. Due to size limitations, we had to reduce the inductor down to 1uH.

As of now, I am doing testing on an 8ohm dummy load. I plan to change the feedback resistor as I continue. The following components have been changed from the original evalution board:

Cc = 18.4nF

Rc = 15kohm

Rfreq = 127 kohm

Rfb = 75kohm

L = 1uH

What I have found is that the output voltage is behaving like a very slow PWM signal (6Hz). It periodically falls to 0V, and then climbs back up. Oscilloscope shots included.

Does anyone recognize this behavior? What would you suggest? I have plenty of current with the current circuit, but I cannot get a stable output voltage.

Thanks.