TPS55288: Bode Analysis for internal mode

Hi Andrew,

You need to shift to external feedback mode to test bode plot. Here's the step based on the TPS55288EVM board:

1. Set the jumper JP2 and JP3 according to the  attached user guide section 2.2.2. 

slvubo4 BMC045.pdf

2. Set the TPS55288 silicon works in the external mode via I2C control, please refer to datasheet '7.6.4 VOUT_FS Register(Address = 4h)',  set bit7(FB) to 1.

3. Inject the signal across R3 to test bode plot. (below picture shows the R3 location, it is in series with the upper side dividing resistor.)