Can someone please help with the following. The Microchip site no longer lists specs for the (discontinued?) 16F628-20 so it's hard to compare.
Is the 16F628A clock 20Mhz?
Will the 16F628A run programs written for the 16F628-20 without modifying the code?
Do I understand correctly that the 16F628-20 supply requirements were
Thank you for any advice on these points.
Robert Davies
See document DS40048A. And the respective data sheets, of course.
Best regards, Spehro Pefhany
Actually the data sheet is still available. The standard device was the 16F628. The -04, was a 'downmarket' version, that was only warranted to clock to 4MHz, and it was only after this came out, that they added the -20 designation. There was never a seperate data sheet for the -20. You might want to consider the 16LF628-20, which is still available, and is exactly compatible, except for a lower power consumption, but has 0.5v higher supply requirement for 20MHz operation.
Look in the data sheet. The maximum clock depends on the supply voltage. The 16F628, ran down to 3v, but was only specified to run at 20MHz, above
4v. The 16LF628 required 4.5v to run at 20MHz.
Possibly!. There are however some erratas that my cause problems, and some changes to the oscillator configuration, that may 'bite' for slower oscillator configurations.
The specified maximum supply, was 5.5, on the 16F628-20, but is contradicted in the data sheet, with the maximum Vdd, given as 6.5v, but then Vdd Max listed as 5.5v, in other parts of the same sheet.... The 'A', will operate down to just 4.5v, at 20MHz, the same as the LF. Microchip are very 'annoying', with some 'A' variants, being completely different chips, with as many changes as exist between other models in the range, and others being only slight tweaks. The 628A, falls into this latter category, and for 99% of code, will run in place of the 628.
Best Wishes
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