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Regarding the PCB layout requirements

Category: Hardware
Product Number: AD8228BRMZ, AD8228, AD8228, AD8228

Hello Experts,

Basic questions regarding PCB layout requirements. I would like to know which pins require what treatment in the PCB layout.

For my understanding:

-IN / +IN, G1 / G2, REF, Vout: These pins can be connected with narrow traces (75um, 100um wide traces, etc.). This is because it is a type of signal net.

-Vs / +Vs: These pins should be connected with wider traces (such as 300um traces). Because it is a type of power net. However, the power consumption is very low (~ 20mW). Full plane connections are not required.

Please let me know if there is any mistake in my understanding. Also any other critical requirements.

Reference datasheet

https://www.analog.com/media/en/technical-documentation/data-sheets/AD8228.pdf

Thanks,

Tsukada

Thread Notes

Top Replies

    •  Analog Employees 
    •  Super User 
    Mar 19, 2024 +1 verified

    Hi  

    Thank you for reaching out to the team.

    I would like to ask several items below to understand the design requirements and applications better.

    • What are the intended end applications? Signal…
    •  Analog Employees 
    •  Super User 
    Mar 19, 2024 in reply to Tsukada +1 verified

    Hi  

    Correct, the dual supply configuration has a symmetrical (same absolute value) voltage being forced on +Vs and -Vs. This case is +/-15V.

    Regards,

    •  Analog Employees 
    •  Super User 
    Mar 21, 2024 in reply to Tsukada +1 verified

    Hi  -San,

    The shorter the trace length from Input pins to a connector or source is better. To eliminate parasistics (line capacitance, impedance, etc..) that will have an effect to your signal integrity…

  • Hi  

    Thank you for reaching out to the team.

    I would like to ask several items below to understand the design requirements and applications better.

    • What are the intended end applications? Signal conditioning, measurements, etc..
    • What are the target supplies for this part? Do you intend to use a single or dual supply configuration?
    • What are the desired input signal and input levels for AD8228? Is this purely DC, or does it need a differential signal?

    Regarding your questions:

    Typically, I use these guidelines for board layouts:

    • Input pins: trace widths are 10 mills (~250um)
    • Supply pins:  min trace widths are 20 mills (~500um), depending on the power consumption; it can go as high as 40mills (~1000um)
    • Output should be wider than Input pins as to eliminate parasitic resistance.
    • For low-power applications, 500um is enough.
    • You might consider REF pins as supply pins if you use a source to offset your output levels.
    • Please look at pages 17 to 18 of the DS for additional layout considerations for this part. AD8228 Low Gain Drift Precision Instrumentation Amplifier Data Sheet (Rev. 0) (analog.com)

     I hope this suggestion will help you.

    Regards,

  • Hi Arsol-san,

    Your answers solved the problem I'm facing now. Also, Thank you for giving me a good perspective in the first half.

    Since we were referring to a circuit diagram created by the customer, we did not know the exact method of use. Next time, I will ask the customer for more details.

    On the other hand, there were some words that I did not understand well. Does "single or dual supply configuration" refer to the conditions for applying voltage to +Vs/-Vs? In actual application, +Vs/-Vs=+15V/-15V.

    The -IN/+IN and Vout will have a trace length of 100mm to 200mm, but if you have any concerns regarding this, it would be helpful if you could give us some advice.

    Thanks,

  • Hi  

    Correct, the dual supply configuration has a symmetrical (same absolute value) voltage being forced on +Vs and -Vs. This case is +/-15V.

    Regards,

  • Hi Arsol-san,

    Thank you for the clarification.

    Please let me know if you have any advice the following point.

    >The -IN/+IN and Vout will have a trace length of 100mm to 200mm, but if you have any concerns regarding this, it would be helpful if you could give us some advice.

    Thanks,

  • Hi  -San,

    The shorter the trace length from Input pins to a connector or source is better. To eliminate parasistics (line capacitance, impedance, etc..) that will have an effect to your signal integrity and possible voltage drop.

    Regards.