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Powering Circuit Q's

Hello,

I am have some questions regarding the Schematics of the BF548 ezkit (attached). Specifically

the powering sections.

Firstly, a basic questions, what is the difference between the filled square and hollow

circle schematic symbol for the power buses? The page Power Page 1, for example,

on the bottom right shows the circuitry for the VDDEXT and 3.3V, shown as filled square

and hollow circle respectively. They are both 3.3V so what is the difference?

Looking now at Power Page 2, I don't really understand the power supply for VDDDR and

5V. What does the adp1823 chip setup do? I looked briefly at its datasheet but didn't

understand how it relates to the regulation of VDDDR and 5V (again the symbols are different?).

On the bottom left of this page there are two outputs for 5V_USB? Why?

Also, on the bottom right there are these symbols (MH4, MH5, etc) but they aren't connected

to anything? What are they for?

It's pretty evident there are lots of things that I'm confused with - the power circuitry has been

a bit of a hurdle. Is there an easier design for the power supply? Would really appreciate

any reference designs that have a simpler powering system.

Thanks to anyone who can be bothered to try and help. I know it is not exactly 'fun', but it

will be much appreciated.

Cheers...

A0206-2006_CUST.pdf
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  • Hello,

    Yes, they can help you out to simplify the power circuit.

    I would recommend  you formulate an email with your power requirements and send an email to linear.apps@analog.com

    Important information they would need in the email are:

    1.) your Vin (power supply) voltage and current,

    2.) what voltage rails you need and the current requirements

    3.) any special power sequencing needed.

    Not using the hard drive should help you to not have to use such a large power supply.

    The hard drive requires between 0.5 to 1A instantaneous current at power up of the hard drive.

    Good luck.

Reply
  • Hello,

    Yes, they can help you out to simplify the power circuit.

    I would recommend  you formulate an email with your power requirements and send an email to linear.apps@analog.com

    Important information they would need in the email are:

    1.) your Vin (power supply) voltage and current,

    2.) what voltage rails you need and the current requirements

    3.) any special power sequencing needed.

    Not using the hard drive should help you to not have to use such a large power supply.

    The hard drive requires between 0.5 to 1A instantaneous current at power up of the hard drive.

    Good luck.

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