In my device 6.5V is generated from 5V USB. This can be done by boost converter, but if something goes wrong (external resistor voltage divider break up), due to overvoltage output condition (for example 16V) all parts connected to boost converter output will be destroyed. Output should never go over 7V.
I am looking for bullet-proof solution (low cost and minimum number of parts, of course). Required current is about 100mA, and efficiency is not so important, because this part of device is used very rare, and it is active during short period of time (1 second).
Closest one that I found is tps61220, but per datasheet, maximum output voltage is 6.0V, while overvoltage protection threshold (internaly) is in 6.0-7.5V range. I am afraid that due to output voltage close to 6.5V, overvoltage condition will be fired non-stop.
I am not interested in boost converters where overvoltage protection treshold is defined by external resistors, because again there things can go wrong.
I can use (100 mA) voltage doubler (charge pump) from 5.0V (USB) to 10V, and then regulate it down by LDO to 6.5V. Or regulate 5.0V (USB) to 3.3V by LDO and than double it by charge pump to 6.6V.
Edit: Let say that due some reason one of 0603 on board resistor fail. Board will not work anymore, but failing of this resistor will not cause any other damage. After replacing this resistor board will continue to work normally. There is LDO (5V from USB to 3.3V or lower voltage selectable by user) on board that can fail, but 5V passed from USB directly will not destroy the board. With boost converter this is not a case, and failing (because of any reason, with overvoltage on output) will destroy board (almost) completely.