Use 3.3V to program Low voltage chips?

[Nora]

Hi-
I'm trying to make the jump from 5V to 3.3V and have had a series of bad decisions and things that don't work etc. I need to get a programmer-chip setup that is compatible with both MP Lab and the CCS compiler.
I'm currently using the PIC18F2423, and someone pointed out that the PICLF2423 is really what I need.
The LF version is not supported by MP Lab and I'm not even sure that it is a real part. Every time I try to order it from the Microchip website, my cart goes empty. It goes into the cart, but I cannot purchase.
Frustrating!!

When programming a low voltage chip, does the programming voltage need to be 3.3V? I ask because I have a PICDEM plus board that does not have a 3.3 supply.

Is it necessary to use pin B5 for ICSP, and if so, which pin is unused, B6 or B7?

What about fuses? Use something to indicate low voltage programming?

Thanks in advance for help!
Nora

[PCM programmer]

[Nora]

Thanks!

But does the low voltage operating chip need to be programmed with low voltage? I'm confused...my USB puts out 5V, so how do I program with 3.3?

N_N

[PCM programmer]

From your previous thread here, I see that you are using an ICD2
programmer:
http://www.ccsinfo.com/forum/viewtopic.php?t=45811
(You really should have kept this as all one thread, since it's all related topics).

The ICD2 can program PICs which are running at 3.3v. Look at the
ICD2 page:
http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1406&dDocName=en010046
It says:

[Ttelmah]

You program the low voltage PIC at low voltage. Some of the newer chips _do not_ support operation at 5v (look at the 18F46J50 for example - 3.6v _max_ supply voltage).
What is wrong, is not realising that the USB supply is not directly used. The ICD, has a little chopper circuit to develop it's internal supplies, and regulates these, and then has a little DAC, it uses to set the voltage fed to the actual chip.

Best Wishes