PIC MICROCONTROLLER HAVING TWO VDD AND VSS ?

[naveshece]

HI,

WHY PIC MICROCONTROLLER HAVING TWO VDD AND VSS ?

PLEASE HELP.

 

[surfman]

There is:


Vdd=+5V
Vss=GND

 

[naveshece]

There is:


Vdd=+5V
Vss=GND

why they are 2 nos?
in normal 8051 microcontrollers are having one..

 

[matbob]

Hi naveshece,

I'm not sure but may be to draw more current that a single pin can't handle or may be to simplify PCB design:!LOL).

 

[GrandAlf]

I think they have just used spare pins on the package to ease pcb layout. Not 100% on this. I know they work with either connected, but I still try to use both. Useful if you need to transfer power across the chip to save long track runs.

 

[elmuhamady]

This is done to improve the dynamic current distribution inside the chip.Also I think more Vss is better for high frequencies.

Amr

 

[karesz]

Hi,
As elmuhamady sayd; to improve the dynamic current distribution, and for less "ground bouncing", because PICs are builded as CMOS ICs; they switches with relative high-speed & more high currents trough transition times as a "normal 8051".....
This current knock/push makes disturbances/potential swifts in resistances & inductances of GND/Vcc lines_called GND-bounces...
Their are to eliminate-minimum to become smaller_ trough more or parallel used pins.
K.