Parsing PIC part numbers by 'rule of thumb' isn't *THAT* difficult.
1. locate the first pattern <digit><letter>, The FAMILY code is everything up to and including the number. (note 1)
It also tells you something about the pin count or architecture. Numbers of the form (where x is any digit):
- '1x' are all 8 bit data bus and 12, 14 or 16 bit instruction word
- '10' are 6 pin SMD (or 8 pin DIP, but a different pinout to PIC12),
- '12' are 8 pin
- '16' are >= 14 pin
- only '18' are 16 bit instruction word
- larger numbers are 16 bit data bus
- except '32' which are 32 bit data bus MIPS core.
2. the letter or group of letters indicates the technology, but this varies by family. For PIC10/12/16/18 (the 8 bit data word PICs):
C is EPROM program memory (OTP unless windowed CERDIP)(note 2)
F is FLASH program memory, (electrically erasable)
HV is FLASH + a shunt regulator for operation from supplies >5V
LF is FLASH + low voltage operation(note 3)
3. you then have the sub part number which may or may not have one or more letters modifying or supplementing the technology code embedded in it. This is the difficult one and only familiarity will help.
For PIC12/16, numbers of the form:
- '1xxx' are Enhanced Midrange, 14 bit instruction word
- '5x' and '5xx' are generally Baseline, 12 bit instruction word
- The rest are generally standard Midrange, 14 bit instruction word
For PIC18, the first digit is a clue to the pin count:
- '1' is 18 or 20 pin
- '2' is 28 pin
- '4' is 40 pin
- '6' is 64 pin (SMD)
- '8' is 80 pin (SMD)
- '9' is 100 pin (SMD)
For PIC12/16/18, when a part was designed to replace an older part the new part number was often obtained by adding an extra digit at the end (or for PIC12/16, also at the beginning) of this part of the number. This can be a clue to finding parts with a compatible pinout, but is far from certain.
For PIC18, parts with a letter in the middle of four digits are often the new technology upgrade or replacement for the part without the letter - but beware of supply voltage differences.
4. a terminating A usually indicates a die shrink or feature revision requiring a new datasheet. Usually very close to 100% code compatible with the non-A part, but programming + electrical ratings will differ.
5. bulk packed parts supplied on a tape carrier wound on a reel (tape & reel) generally have a T inserted in the order code at this point in the part number. It does NOT appear in the part number on the actual chip or when searching for data.
6. extra codes up to the first /:
-<number> is max speed in MHz
-<letter> is temperature range: I industrial or E extended.
also -<number><letter> as above
-ICD -ICE are special debugging/emulation bondout chips. non-standard pinout and NOT available loose
7. after the / is the package type, Usually fairly consistent and documented on the individual product pages.:
/JW Windowed side brazed CERDIP (now vanishingly rare - Erasable UV-EPROM development parts)
/P PDIP (normal leaded "plug in" chips. Width 0.3" (8 to 20 pin) or 0.6" (a few 28 & all 40 pin)(note 4))
/SP SPDIP (normal leaded "plug in" chips. 28 pin narrow width 0.3")(note 4))
/SO SOIC (small-outline integrated circuit SMD)(note 5)
I am skipping the other SMD packages because you WILL have to make a PCB for them or buy a demo board.
1. There are some old or special purpose devices that don't fit this rule e.g. the long obsolete PIC1400 or the current MCP2200 which is a USB to serial chip that is a custom programmed PIC18F14K50.
2. There are some exceptions, usually when technology got ahead of marketing e.g. PIC16C83, PIC16C84 are actually the first FLASH tecnology parts. The exceptions are pretty rare and can be dealt with case by case.
3. "Low Voltage" is a nebulous term here. Some have an extended minimum operating voltage but the same maximum, others have reduced minimum AND maximum operating voltages. e.g. devices with a low voltage core may leave out the regulator so not be capable of 5V operation.
4. Narrow (0.3") 28 pin PDIP chips (the commonest in this pincount) are described as SPDIP in parts selectors etc. Its annoying because if you want through hole chips including the 28 pin ones, you have to do two searches.
5. 0.05" pitch SOIC devices are just about breadboardable on veroboard. You either split tracks down their center or tack down alternate pins, bend the others up slightly and fly-wire them to where they need to go.
In all cases check the datasheet to verify your decoding. The product range basically "grew like Topsy" which is why the numbers are such a mess.
The easiest way of finding a chip for a specific task is via MAPS
(Microchip Advanced Part Selector) which has a parametric search that works across the whole microcontroller range. If you know the family you want, the individual family parametric search pages (browse down fro the products page) can be useful as unlike MAPS they have the option for multiple selection for some parameters and can also output to spreadsheet that you can download and run a custom search on. Beware: the parts database is known to be somewhat corrupted: e.g.parts allocated to the wrong families, or listed without their ADC - always check the datasheet (and errata) before ordering!
post edited by Ian.M - 2014/07/18 17:43:20