Q: TPS62290 - can it start into a pre-biased output? by 145034

Can the TPS62290 safely start into an output that is pre-biased to some voltage?  Will it sink current from the output?

 
A: Re: TPS62290 - can it start into a pre-biased output? by 1090425

This device can start into an output pre-bias without discharging the output voltage.  Please see the attached ppt with various test conditions.  The device was tested in both power save and PWM modes and with and without a load.

CH2 (top trace in red) is Vout

CH1 (second trace in yellow) is EN or Vin

CH3 (third trace in blue) is the inductor current

CH4 (bottom trace in green) is the SW node

Since the SW node does not start switching before Vout begins to ramp up, the IC is not trying to sink the output voltage.  This is confirmed by the lack of significant negative inductor current.

This applies to any device in the TPS62240, TPS62260, TPS62290, TPS62560, and TPS62590 families.

4503.TPS62290 startup with prebias.pptx