TPS61040 - for phantom power +48v and variable voltage

the circuit is good. but the input voltage of tps61040 should be 1.8~6V. make sure that Vout is lower than max voltage during transient, such as startup, load transient and Vout  switching using FB pin. thanks

boost converter solution team

jasper li

Thanks Jasper, you're right, I was adapting the schematic for a picture and forgot to fix the input voltage.  It will be getting 5v from USB.  

Can you clarify "load transient and Vout  switching using FB pin," I'm not sure I understand what you mean here.  Is there an Application Note that I could read to get a greater understanding?  

Load transient : the load change from 0mA to 100mA for example. 

Vout switching: because you mentioned that you want to change the Vout using a mosfet and a resistor in parallel with R2

Jasper li

Ah!  I believe I understand now, that helps me to parse the sentence better.  

So you think the mosfet switching could work reasonably as long as I do not let Vout exceed spec in the process?  That was what I was hoping.  

According to the datasheet, the part is not spec'd for 48v, but if I keep Vout within wattage specifications and hold the part in SHUTDOWN when switching R2, would you say this is a reasonably safe approach for preserving the life of the TPS61040?  

Thanks again Jasper, I'll post again here if anything comes up.  Your advice is much appreciated!