01-27-2018 03:07 AM
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.
01-28-2018 09:16 AM
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.
01-28-2018 09:27 PM
@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.
02-15-2018 11:40 PM
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