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TPS61170: TPS61170 Oscillation at certain input voltage

Part Number: TPS61170

I'm using TPS61170 to generate +/-25V from 4.5V~6V DC input. The total output current is around 40mA. I made modification based on TPS61170EVM. The components are as below:

Input cap: 10uF+100nF Inductance: 22uH(around 320mohm DCR) Output cap: 4.7uF*3+2.2uF+100nF all are ceramic caps.

Feedback resistor are: Rbot=10kohm, Rtop=180k+18k

Compensation parameters: Rcomp=120km Ccomp=2.2nF, high frequence pole cap is 220pF.

I find the bode diagram are ok with all kind of load throung 4.5V to 6V except one point, when the VIN is around 4.90V~5V, the output will have low frequency oscillation. The bode diagram shows the low frequency phase is negative, and cross 0 degree slowly. Can you help on this? Thanks a lot.