is it alright to run PIC18F4520 at 3v?

[joprinz]

The datasheet of PIC18F4520 states:

"Standard devices with Enhanced Flash memory, designated with an "F" in the part number (such as PIC18F2420), accommodate an operating VDD range of 4.2V to 5.5V. Low-voltage parts, designated by "LF" (such as PIC18LF2420), function over an extended VDD range of 2.0V to 5.5V."

I was unable to source the "LF" version in small quantities for my prototype. So I ran my test circuit using PIC18F4520 at 3v and the circuit functions well. But since the datasheet states the supply voltage requirement to be atleast 4.5v I would like to know if running PIC18F4520 (F version) at 3v will cause any issues in the long run.


Joe!

 

[BeeBop]

The datasheet of PIC18F4520 states:

"Standard devices with Enhanced Flash memory, designated with an "F" in the part number (such as PIC18F2420), accommodate an operating VDD range of 4.2V to 5.5V. Low-voltage parts, designated by "LF" (such as PIC18LF2420), function over an extended VDD range of 2.0V to 5.5V."

I was unable to source the "LF" version in small quantities for my prototype. So I ran my test circuit using PIC18F4520 at 3v and the circuit functions well. But since the datasheet states the supply voltage requirement to be atleast 4.5v I would like to know if running PIC18F4520 (F version) at 3v will cause any issues in the long run.


Joe!

If it is working at 3V now it probably will be OK. Wouldn't use it for a production run, but prototype should be OK. When a manufacturer posts a data sheet they give you values that the part is guaranteed to work at. According to the data, Microchip guarantees this part to work on a supply as low as 4.2V.
They spec parts to operate from DC to 20 MHz, but some users clock them faster and they work. Just like over-clocking your PC processor.

 

[Oznog]

Datasheet for 18f2420 shows a minimum of 4.2v for ANY operating frequency.

Your part may not operate correctly. It may operate in one temperate but not another. Or, it may seem to be operating correctly yet some odd bug occurs when you use a feature. It may not be able to program the EEPROM region. In short, it's no guaranteed to fail, but it's not guaranteed to work. It is unspecified. IMHO, it is a waste of time to try to use it this way since I'd suspect the voltage issue for just about any bug encountered.

 

[joprinz]

Thanks Guys... Somehow L versions of PIC is hard to find around here... I have decided to redesign the whole circuit using ATTINY48 (its available and it works from 2.8v to 5v).

Thanks Beebop, Oznog for your inputs.

Joe!