> I've been using devices from this family for a while and all them, accord=
ing to
> my experience with PICKIT3, seems to require at least 3.5VDC while being
> programmed, otherwise fail to program. Sometimes I can get them to
> program as low as 3.35VDC but most of the time they won't, whereas 3.5VDC
> seems to be good enough 90% of the time. I've never been able to program
> these parts with 3.0VDC which is within specs.
>=20
>=20
> The programmer used is PICKIT3 with external power in a circuit, but beha=
ves
> the same if I connect an isolated device to PICKIT3 itself, using self po=
wer or
> external power. No difference.
>=20
>=20
>  The microchip programming specification for these parts is 3.0-3.6V
> (parameter D111 on DS70619B document) with an instantaneous current
> during programming of 200mA (parameter D114). Looking into the errata for
> these parts does not mention anything regarding programming voltages that
> could lead to think this is a known issue.

My response would be to ask how you are measuring the voltage.

Using the PicKit3? This, to me, would be a highly suspect way to do it.

A DVM at the chip itself? This would be the best way, especially if it is a=
 known calibrated DVM, and ideally has a max/min function like the Fluke 89=
 IV or similar meters, which will track the voltage changes and allow you t=
o read them out later.

How is the PCB arranged? Planes for both Vcc & Gnd, with recommended caps o=
n all power pins? Note that the Vcap pin MUST have the recommended cap valu=
e on it. IIRC the recommended value is 10uF ceramic or other low ESR, altho=
ugh IIRC they do say you can go to 4.7uF. I do seem to remember this issue =
coming up in the Microchip forums, and this being a MUST DO.
--=20
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--=20
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