9.3 Do's and Don'ts

There is a known issue with the TPS61165 when using the EasyScale interface to increase the feedback voltage. When V_FB is increased from 0 mV to any value above 0 mV, some ICs do not properly soft start during this transition and the voltage on their SW pin overshoots. If the overshoot exceeds the absolute maximum voltage rating on the SW pin, the device is damaged.

With VFB set below 10 mV through EasyScale, the parasitic offsets on the input pins of the internal trans-conductance amplifier determine the value of output of the amplifier. Device process variations are causing the offset to be larger and in the opposite polarity than expected. If the amplifier’s output is already high prior to a transition from V_FB = 0 mV to any other voltage, then the modulator turns on full, bypassing soft start, and causes the SW pin and output voltage to overshoot.

To avoid this issue do not use EasyScale to change the feedback voltage from 0 mV, effectively disabling the device, to any other voltage. One alternative is to start with VFB = 10 mV and go to a higher voltage. Another alternative is to disable the device by taking the CTRL pin low for 2.5 ms and then re-enter EasyScale to force a soft start from V_FB = 0 mV to the default 200 mV.