dual VDD and VSS

[slurp.lolipop]

Good-day all,

I am working on a project that interfaces the PIC16f877A and the PC.


Q1) In general, PIC16F877A,the VDD at pin11 and VDD at pin32 are the same, right? [YES/NO]

Q2) when I draw my PCB layout, I draw a connection across the PIC to connect
the pin11 and pin32 together, correct? [YES/NO]

Q3) in my schematic, at each sides of the Vdd, I noticed they are either connected to a capacitor (pin11) or to a parallel-pair of capacitors (pin32), and are then connected to 5V each side.
At pin32, it is connected to the parallel-paired of capacitors and also connected to 5V.

(5V)
|
|
(pin32) >>>>>>>* (one end of the parallel-paired capacitor)
(pin31)>>>>>>> * (another end of the parallel-paired cap)
|
|
(ground)
my Q3 is
When I draw my PCB Layout, Can I connect the Vdd(pin32) to Vdd (pin11) across the PIC....then I CONNECT the VDD (pin32) to the parallel-paried capcitors ONLY.

My rationale is, when VDD of pin32 connects with VDD of pin11 (by drawing a connection line across PIC16F877a)
VDD of pin32 will also be connected to the 5V that pin11 is connected to.

Is that correct? [yes/no]

OR

I still have to draw Another CONNECTION LINE in my PCB layout...
connecting the
VDD of pin32 + parallel-paired capacitors to the 5V power source?

Please advice.

cheers,
slurp

 

[mvs sarma]

You may have to tie both Vdd together and likewise both Vss
Also place a 0.1uF cap across the power pins close to the chip.

 

[Nigel Goodwin]

Yes, always connect BOTH pairs of pins, and always add a capacitor (or two) across the chip.

 

[JimB]

Just to clarify one of the points which may not have been already covered, connect the two +5v and connect the two 0v pins together at the chip (dont forget the capacitor).
Then you just need one connection from the pair of +5v pins to the 5v supply and one connection from the pair of 0v pins to the 0v supply.

I think we have now covered all variations of your question!

JimB