why somebody does not use a "special" chip.
when so, you usually end up with a worse, more expensive, and, sometimes, ARGH a "calibration requiring" design.

I do appreciate that some things MAY be difficult to obtain in Farawayistan, but last I looked both DigiKey and Mouser will ship all over the world, let alone that Farnell/Newark seems to be mentioned as having offices all over. From some posts I get the impression that, for some, even in countries where e.g. Farnell has an office, the attitude is "if it is not available in the bazaar, I will not use it"

If you happen to have a nail in your drawer, that does not mean it is a good substtute for a screw.

Erik