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Visitor spa16
Visitor
1,059 Views
Registered: ‎01-27-2018

Spartan-3AN PUDC_B VCCO_0 if necessary

Hello. I'm using Spartan-3AN in my project. I plan to use internal pull-up resistor on Pins with Optional Pull-Up Resistors during configuration. Now the pin PUDC_B is connected to ground with extarnal 10k resistor. If is nesseassary to apply voltage to VCCO_0 pin in this case? Or I can connect VCCO_0 to ground with 10k resistor too? Or I need to provide non zero voltage on this pin during configuration anyway?  Actualy I'm not plan to use Bank 0 pins in my design. This why I not need any voltage on VCCO_0 pin. Thank.

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3 Replies
Scholar austin
Scholar
1,011 Views
Registered: ‎02-27-2008

Re: Spartan-3AN PUDC_B VCCO_0 if necessary

Vcco pins require power if any pin in the bank is used,

 

The bank used for configuration must be powered.

 

An unused bank draws less than 2 ma, so connecting to ground saves little power.  You may be better off powering it and bringing out 2 or3 pins just for debugging or test.

 

 

Austin Lesea
Principal Engineer
Xilinx San Jose
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Xilinx Employee
Xilinx Employee
999 Views
Registered: ‎08-01-2012

Re: Spartan-3AN PUDC_B VCCO_0 if necessary

@spa16--As Austin informed Vcco  must be powered because it is having configuration interface. With out VCCO_0 supply voltage the FPGA do not configure. So even if you do not use bank 0 IO pins VCCO_0 supply voltage is must

 

A Low level applied to the Pull Up During Configuration (PUDC_B) input enables the pull-up resistors on user-I/O and input-only pins from power-on throughout configuration. PUDC_B must be stable before INIT_B goes High and constant throughout the configuration process. Even to sense the PUDC_b also VCCO_0 supply voltage is must. 

 

Additionally to know more details about Spartan-3 generation FPGA configuration details please refer https://www.xilinx.com/support/documentation/user_guides/ug332.pdf 

 

In case of using in system Flash configuration modethen refer https://www.xilinx.com/support/documentation/user_guides/ug333.pdf to know more details of in-system Flash usage guidelines. 

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Xilinx Employee
Xilinx Employee
893 Views
Registered: ‎08-01-2012

Re: Spartan-3AN PUDC_B VCCO_0 if necessary

@spa16

Did your query answered? If yes, please close the thread by clicking on “Accept as Solution” tab for that particular reply posts which were more helpful for you. That will be helpful for other users.

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