I am working on USB microcontroler (flasher) board and looking for the best way of voltage selector (for fuse blow) between 2 sources.

There is 5V from USB, and on board will be 5V -> 2.0V-3.6V digitally controlled regulator. Also there will be possibility (jumper) to use external 2.0V-3.6V supply instead of on board regulator.

During fuse blow, 6.5V must applied to target device pin (and during blow fuse target device is powered on 2.0V-3.6V).

One solution is to boost (Step-Up Switching Regulator) 2.0V-3.6V to 6.5V, and when it is disabled to have 2.0V-3.6V from input with diode drop. Another solution is to use voltage doubler with 5V USB, double it to 10V and regulate after to 6.5V. And have 2.0V-3.6V in parallel isolated with diode. Or to regulate USB 5V to 3.3V and double it after.

2.0V-3.6V will be for max 1A, and 6.5V for max 200 mA. is Is there any simple enough / elegant solution for this? Or perfect one without 2.0V-3.6V any voltage drop?

Thanks.

 

Not sure I understand what you are looking for.
What is the 6.5V about?
Do you have a circuit diagram of what you have so far?

 

Not sure I understand what you are looking for.
What is the 6.5V about?
Do you have a circuit diagram of what you have so far?

Looking for low cost, simple as possible, device with 2.1V-3.6V input supply (changing on-the-fly, selected by end user), and enable/disable pin (that working on logic levels as input supply). When enable/disable pin is low, device will give on output supply from input (2.1V-3.6V). If enable/disable pin is high, device will give on output close to 6.5V (boosted from input 2.1V-3.6V).

Probably will end with MCP16252, only question is regarding dropout voltage (between input and output) when device is disabled.