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Thread: Engineering information request: Z77E-ITX VRM circuitry question




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    Default Engineering information request: Z77E-ITX VRM circuitry question

    I'm currently working on a very tiny build (uSFF gaming rig) and have a power supply that I want to use. Almost all of the specifications line up to what I need, but I was wondering about one thing with regards to the ASRock Z77E-ITX motherboard.

    The VRM step down stack which takes the power from the EPS12V and produces the various voltages required for the CPU -- what is the total V-in range that is applicable for this circuit? Most adjustable buck stepdowns that I've worked with have a very wide range of input voltages (such as 0.5VDC up to 40VDC), so I would like to know how large of a range I have to work with on the processor power line with this motherboard :D


    If you cannot provide this figure, an alternate way to answer my question would be if you could provide the specification part #'s for the capacitors, inductors, and a circuit diagram; I figure this is probably relatively straightforward to determine from a scan of the board, but wanted to get it straight from the experts :)


    Thank you in advance!

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    Default Re: Engineering information request: Z77E-ITX VRM circuitry question

    In a follow up to my own question, I know how the actual CPU voltages are produced, through the ISL6367 6-phase VRM chip, but I'm wondering how the EPS12V current is converted to the 5VDC for this chip (i.e. what is the V-in range on whatever is doing the step down to 5VDC prior to the "main" voltage regulator).

    Thanks again!

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    Default Re: Engineering information request: Z77E-ITX VRM circuitry question

    Ok, so tracked this to the ON Semi NCP5369 MOSFET buck converter chips which look like they have a Vin range up to 30V.

    Any engineers around to tell me I'm crazy before I toast this board with a healthy dose of 19.5VDC?

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    Default Re: Engineering information request: Z77E-ITX VRM circuitry question

    disregard. first boot successful and counting.

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    Default Re: Engineering information request: Z77E-ITX VRM circuitry question

    Interesting questions, not that I'm sure I understand your motivation. Sounds like you want to use a non-standard power supply, at least for the EPS CPU power input, whose voltage is not 12V but higher.

    I imagine I don't need to tell you to monitor the heat sink temperature of the VRMs, and possibly the other components involved, capacitors and inductors, and the voltage ratings of the latter or both.

    I don't know if this "review" of the ASRock Z77 Extreme 4 and Extreme 6 will be helpful to you, but here it is below. The author takes a fairly close look at the VRM chips used on these boards, and identifies them by manufacture and part number. Will either of these boards have the same parts (Intersil ISL6367) as your board? That of course in the question. Scroll down a fair amount to find discussions of the VRMs:

    ASRock Z77 Extreme4 & Z77 Extreme6 Review

    ASRock's participation in this forum has been limited to one representative for a while now. I have no idea of the extent of their familiarity with the level of detail you require, or if that information would be retrieved for you.

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    Default Re: Engineering information request: Z77E-ITX VRM circuitry question

    Thank you for your response - I tracked the parts on my actual board back through the VRM module (intersil part - on the back of the mobo) then through the buck step down circuit (one mofset per phase - they are the chips under the heatsink on the front of the mobo) and the data sheets indicate that a V(in) of 19.5VDC is within the normal operating range. I will definitely have an IR thermometer pointed at the relevant parts during the shakedown cruise :)

    I am using the 330W power supply from the alienware X51.

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    Default Re: Engineering information request: Z77E-ITX VRM circuitry question

    Oh I see, Dell and their proprietary designs... or they know they can just use that voltage with their boards.

    The voltage may not make a difference, as long as the same amount of current or power (Watts) are dealt with, the VRMs will be fine, right? Won't cheapo opamps have a range of 9V - 18V on their V input, so why not those components? Heck, they might even work better.

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