Q: TPS61253 - operation for Vin > Vout by 1940398

Hi TIer

TPS61253 has input voltage range of 2.3 to 5.5V.

So, when Vin is above 4.5V. Is there any operating mode? things like 'pass through mode' or something?

Also when Vout(5V) is less than Vin(5V ~ 5.5V), Output is disable or Vin level?

1. Could you explain operation of TPS61253 when this device Vin level is form 4.5V to 5.5V?

2. And when Vin is 4.5V to 5.5V, is it OK for IC's safety?

3. And when Vin is 4.5V to 5.5V, is it OK the output current is 1A continously?

 
A:

This question is answered in the datasheet, page 17.  This section describes that the IC can enter 0 duty cycle mode and not boost the input voltage if the output gets too high.  It then refers you to figure 13 that shows as Vin rises above Vout, Vout rises with it.  Essentially this is pass through operation.  The IC does not shutdown, it simply stops switching and does not boost the output further above the setpoint.  This is safe for the IC and it can supply the rated current so long as there is thermal fault due to excessive losses in the IC and assuming EN = 1.