I am powering DDR4 memory with a TPS62136. The output voltage is 1.2V. The inductor is a Coilcraft XGL4020-222MEC, 2.2uH, 20mohm. The output capacitors are a pair of GRM31CR60J476ME19L, 47uF, X5R, 6.3V, 1206. As the transient test is running and the board is heating up, the 1.2V rail will take on a ripple-like oscillation on top of the 1.2V with approximate frequency of 17-20 kHz and amplitude of 200mVpp. I have not been able to recreate this in WEBENCH simulation.