eblc1388 said:
The general consensus among PIC users are that PIC requires a programming voltage of 13V or higher in order to be programmed sucessfully. This must be a carry over from past experience with PICs that actually exhibited such behaviour. As such one always get the same advise in the forums, even after several generations of PIC design.
From the list posted by Mike, there are only a very few, very new PIC's which aren't specified for 13V.
Perhaps there is still some truths in the above statement for those PICs that are one time programmable and a few 16F7XX.
No, you're too new to PIC's to remember back that far :lol:
The original David Tait programmer was designed ONLY for the 16C84, which was the only EEPROM based PIC for a many years. The first DOS versions of PicProg (before it became WinPicProg) only supported the 16C84. At that time many of the OTP PIC's were programmed in a parallel mode, using far more complicated programmers.
The success of the 16C84 led to further EEPROM based PIC's, AND to the inroduction of serial programming on later devices.
The question is actually quite simple. If a PIC programmed well using 12V, would one risk damaging it using 13V or higher? What's the advantage of using 13V or higher if 12V is equally as good?
The 16C84 didn't require 10V to 13V, like many on the list, it required at least 12V, and also drew a reasonable amount of current. For programming reliability 13V became the accepted value used, as 11.9V wouldn't work, using 12V was very marginal. Using a 7812 was a problem, due to the losses through the circuit, particularly in the Vpp switching transistor. A common solution was to add a silicon diode in it's ground pin, to give a 12.7V rail - and that worked fine. The 13V solution comes about by using an 8V regulator sat on the output of the 5V one, or if you're using an adjustable regulator, 13V is a much rounder figure than 12.7V or whatever.
More modern devices no longer draw current from the Vpp line, the actual programming voltage is generated internally in the PIC, and the Vpp voltage is only used as a switching input. Assuming that is so on the new devices, I fail to see how 13V would cause any problems?, presumably MicroChip will eventually make an announcement on the situation?.
From what's been posted so far though, it's interesting that the MicroChip ICD2 uses a 13V switching voltage?.