ICD-U40 with ICSP of 3.3V Target Device

[bdavis]

I have heard you can use the ICD-U40 with a target running at 3.3V, but have some questions concerning the configuration bits and block erase.

Is it true that you can not perform a block erase if Vdd=3.3V and Vpp=12V?

Can I set/reset all of the configuration bits/fuses except the code protection configuration bits if Vdd=3.3V and Vpp=12V?

I want to use ICSP (and ICD) with a TQFP PIC18LF452 running at 3.3V, and can not remove the device for programming, and I can not set the Vdd to 4.5V or 5V due to the circuit design.

If I don't ever code protect the PIC, can I change the other configuration bits (OSC, DEBUG, BRNOUT, STARTUP TMR, etc) whenever the ICD2 is connected? I plan on using a bootloader for FW updates, but the configuration bits would not change when the bootloader was run.

Anyone know what the jumper is for inside the ICD-U40?

[bdavis]

I called Microchip, and got the following answers - I had to be sure this was true...

With Vpp=12V and Vcc < 4.5V, you can't do a block erase, which is required to change code protection fuses.

All other configuration bits/fuses may be changed with Vpp=12V and Vcc<4.5V

Still don't know what the jumper is for in the ICD-U40 yet...

[Guest]

I found that the jumper in the ICDU-40 is to source 5V to your target. This is only to be used if using 5V, not something like 3.3V and eliminates the need to provide a separate power source for your PIC.