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There will be 8 CIII-25 fpgas on the board.
- what can the total current needed for 2.5V line? i could not see any info on the device handbook.
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I found on CIII datasheet that current for VCCA is about 8mA. Then for 8 devices a 100mA supply could be ok.
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- Can you advise me a LDO from 3.3V to 2.5V.
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There are a lot of devices good for this. Browse the selection guides from any vendor website (Texas Instruments, National or Linear Technology have plenty of LDOs) and then choose one based on availability from your local distributors.
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- We won't need ferrite beads if we use LDOs right? (although 8 fpgas will be supplied from the same LDO output?)
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Probably ferrite beads are not strictly needed when you use a dedicated supply for analog circuitry. Anyway I think placing the ferrite + capacitor filter near the VCCA pins is still recommended; infact, even if 2.5V is not shared with any digital supply, connecting it to 8 fpgas will require rather long traces which could pick up high frequency noise, especially if you can't route them through a dedicated pcb plane.
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