Hi Jasper Li,
As you said in the previous reply I probed the SW pin of the TPS61070 and got these waveforms which are given below:
From these images, we can see that the peak voltage at the SW node is above 10V and at the negative side it is -5V. So we can assume that this will be the reason for dagame causing for the IC. So I decided to design the snubber circuit. After adding the 2.2nF capacitor across the SW pin to GND the frequency gets reduce to half as shown in the below figures:
As you can see the amplitude also resided by adding the 2.2nF capacitor.
By calculating the snubber resistance from the application document, I added a 5-ohm resistor series with the 2.2nF capacitor. Below are the figures after adding the snubber circuits to SW pin:
As you can see the peak voltage is around 7.2V and lowest at -2.5V. By the absolute maximum rating of the IC, the range of voltage that can be withstood by the IC is fro -0.3 to 7V. So I think this won't rectify this issue. Even I added higher capacitor and lower resistors it is not getting below 7V. Could you please check them and help us to resolve the issue?