are Vdd and Vss connected internally?

[karenhornby]

ON a 16F877 it has 2 X Vdd and 2 X Vss

are both Vdd pins linked internally inside the chip, and are both Vss pins connected internally inside the chip?

OR do I have to supply Vdd and Vss to 4 pins instead of 2??

 

[eng1]

ON a 16F877 it has 2 X Vdd and 2 X Vss

are both Vdd pins linked internally inside the chip, and are both Vss pins connected internally inside the chip?

OR do I have to supply Vdd and Vss to 4 pins instead of 2??

I would recommend to connect all Vdd and Vss pins for reliable operation.

 

[blueroomelectronics]

Always connect all the vdd & vss pins.

 

[dknguyen]

THey are connected internally and you can sometimes get away with only connecting one set. BUt they are there for a reason. Better decoupling and your IC can draw more current than what one pair of power pins can handle (you don't really think one of those pins can handle 300mA do you?). THen you get something that fails and you have no idea why,

 

[picbits]

déja vu

This was discussed a few weeks ago if you do a quick search

 

[Hero999]

Perhaps the largest thread that deals with this question could be made sticky?

 

[I²R]

Perhaps the largest thread that deals with this question could be made sticky?

Wouldn't the most concise and accurate be the more appropriate choice here?

 

[Shax]

I'm using a 18F2431 in an electronic altimeter, which has Vdd, Vss and AVdd, AVss. All pins have to be connected to the relevant supply rails for me to be able to program and use the device.
A quick look at the datasheet (397 pages!!! ) suggests that they are linked, but reality proves otherwise!

 

[Pommie]

I'm using a 18F2431 in an electronic altimeter, which has Vdd, Vss and AVdd, AVss. All pins have to be connected to the relevant supply rails for me to be able to program and use the device.
A quick look at the datasheet (397 pages!!! ) suggests that they are linked, but reality proves otherwise!

That is what I would expect, digital and analogue supplies to be isolated. In the OPs case, the pins are connected internally and it depends on the current flow to/from the ports whether both need connecting.

BTW, are you sure you need the analogue supplies connected to program?

Mike.

 

[Shax]

That is what I would expect, digital and analogue supplies to be isolated. In the OPs case, the pins are connected internally and it depends on the current flow to/from the ports whether both need connecting.

BTW, are you sure you need the analogue supplies connected to program?

Mike.

All supply pins need to be connected for ICSP to function on my 18F2431.
With the AVdd and AVss pins unconnected, the pic is recognised by the programmer, but refuses to accept any code.