TPS6261x EN and MODE states

Q:

For the TPS6261x;

-What happens if the ENABLE is left floating.

-For forced PWM mode, does MODE have to be pulled to Vin or as long as Vout is greater than 1V can MODE be connected to Vout.

A:

If the enable pin is left floating then it is undefined whether the device is in operation or not. For some cases an external pull down resistor needs to be added. The Mode pin just needs to have a logic low or high. For forced PWM it needs a logic high. When connecting this pin to the output then the device might start-up with PFM enabled (Vout<1V). However during start-up the device will operate in PWM anyway since the output cap needs to be charged. Because of that you can connect it to the output as well. Although I don’t understand  the reason for doing so.