We are currently trying to use a TPS61165 to power the backlight of a Focus LCDs TFT display module (part number E70RA-I-MW1530-CA). We are using a regulated 5V supply to power the TPS61165. When the CTRL line is low (< 0.4V) we see the SW signal climb to 5V and stabilize. This is expected based on Figure 4 from datasheet SLVS790E, April 2019 Revised. When we drive the CTRL line high the input voltage stays at 5V with no significant spikes. The SW signal drops to approximately 900mV and then slowly climbs back to 5V and stabilizes again. However, based on the datasheet, the SW output should not have dropped at all and the final voltage should have climbed high enough to power the LCD and satisfy the FB requirements.
We proved the LCD works by powering it with a variable supply in our lab.
We have tried changing the inductor between SW and VIN. We have tried changing the Rset value on the FB pin. We have tried multiple boost regulators from our stock. We verified that our layout is exactly as recommended by TI in the datasheet.
I am at a loss as to what could be happening and
