Do I need to bind multiple vccs and gnds together?

[martijn]

chip multiple vcc

the cpld I use is a epm7032slc44, it has 4 vcc's and 4 gnd's. is it necessary to bind them together, or is it enough if I connect just one vcc and one gnd to the supply?

thanks in advance

martijn

 

[cube007]

why multiple vcc

Hello martijn,

It is necessary to tie all of the power pins to a power supply.

Bye,
cube007

 

[weilijun]

Re: multiple vcc's and gnd's

I think it is not enough if you just connect one vcc and one gnd to the supply. You should connect all necessary pins to VCC or GND as required.

 

[mc&fpga]

Re: multiple vcc's and gnd's

some vcc and some gnd pins are connected in chip,but you should connect all of them(vcc)to powersupply and all(gnd )pins to ground,
and don't forget to put 100nf capasitor between them.

 

[mYthorON]

multiple vcc's and gnd's

Evaluate the total current, and draw vcc and gnd in more width, normally >25mil

 

[jay_ec_engg]

Re: multiple vcc's and gnd's

Y its neccessary to tide each VCC an GND togather.... but for that u need to see the datasheet of the chip........Power requirements should be matched...
Peronally I observed that if it saying that VCC should be at 3.3V it may vary from 3 to 3.5V practically....
This VCC and GND is the core voltage of the chip... other VCC is for the IO bank of the chip...for outer interface...

 

[bibo1978]

Re: multiple vcc's and gnd's

It is a bad habbit not to tie all power pads to power signal even if all power pads are internally connect this can result in a more noise effect in your design especially if you are targetting a high speed requirements

 

[alphi]

Re: multiple vcc's and gnd's

Put vcc together,and gnd is in same way.

 

[anand_hdl]

Re: multiple vcc's and gnd's

martijn,

U must try to understand the reason behind having multiple vcc and gnd pins then u do it correctly u r self.

Please refer to following:
https://engineering.dartmouth.edu/~engs031/hansen/labs/projects/WiringCPLDs.pdf.

part of it very relvant to what u want is following:

Powering and BypassingCPLDs require a lot of power in order to work correctly. Because of the amount of transistors, inputs,outputs, and whatnot crammed onto a square flake of silicon, CPLDs have multiple Vcc and GND pins.

 

[yangvic]

multiple vcc's and gnd's

If you only connect one power pin,it can not run stabillity.Maybe it can not work.

 

[martijn]

Re: multiple vcc's and gnd's

thanks for all the reactions! I'll tie all vcc's and gnd's together, better safe then sorry

 

[Fnutik]

Re: multiple vcc's and gnd's

In the .prt - file you can read how to connect all of the pins to the board. It's strongly recommended to do so. Otherwise you may get some diffuculties about designing your scheme.