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Altera_Forum's avatar
Altera_Forum
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17 years ago

Power supply requirements for Cyclone III

I'm looking for information on what the power supply requirements are for Cyclone III devices.

The starter kit evaluation board has 5 different regulators at 1.2V, 1.25V, 1.8V, 2.5V and 3.3V. I was hoping I could skip or consolidate some of these, obviously I need the 1.2V for the core and 3.3V or whatever for the I/O but I'm unsure about the rest.

I intend to use only 3.3V I/O. I have a third party eval board for an older Cyclone EP1C6 and that makes do with only two regulators as far as I can tell.

4 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    17 years ago

    1.2V core supply and 2.5V VCCA are required, others are optional, depending on your application. So if you intend to use 3.3V VCCIO, you need 3 regulators. The VCCA current requirement is low however, a tiny SOT23 regulator is typically sufficient. Even a silicon diode from 3.3V can do in some cases.

  • Altera_Forum's avatar
    Altera_Forum
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    17 years ago

    Ok. I'm also wondering, the FPGA in the EQFP144 case has about 32 supply pins. Is there any guide to what kind of bypass caps I should use with this chip and how many of them? I counted 29 caps on the bottom of the starter kit, underneath the chip but that's a BGA chip with a lot more supply pads than the 32 I have. I'm sure there's a document somewhere about exactly this but I have no idea where to look for it.

  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    I am going to use FPGA for the first time.I have a very basic question here.What is core power?Can I give 3.3 V as input signal to Cyclone III FPGA's even though power supply requirement is 1.2V,1.8V etc.

  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    The FPGA uses different power supplies for different parts of the chip. The Cyclone III requires a 1.2V supply for its core and 2.5V for its plls, and you can use any supply voltage between 1.2 and 3.3V for the inputs/outputs.