Post Go back to editing

Neet to review the schematic

Category: Hardware
Product Number: AD8479

The customer asks for reviewing the schematic with AD8479.

They are developing BMS solution for UPS system with lead-acid battery.

It is designed as a discrete as the picture below. 

- Conditions

1. Common mode voltage of AD8479 is 600V.

2. the voltage of lead-acid battey is 14V.

3. 48 lead-acid battery are connected in series, and the total volatge is 672V.  

4. Trying to lower the voltage actually applied to AD8479 input terminal through voltage divide.

so that, they would like to know whether this was designed properly or not. 

please take a look at the schematic, and then please advice if there is any kind problem.

or if you have any other solution, please let me know it. 

Top Replies

    •  Analog Employees 
    •  Super User 
    in reply to derekl +1 verified

    Hello  ,

    The schematic you provided will work, but I noticed a typo which should be corrected to 14V. I also have a concern regarding impedance matching, which the customer may consider. 

    As I mentioned…

Parents
  • Hi  ,

    I am currently reviewing the provided schematic. I will let you know if this schematic works.

    Thanks,

    Mae

  • thank you for your kind support.

    I am going to wait for your answer. 

  • 0
    •  Analog Employees 
    •  Super User 
    in reply to derekl

    Hi  ,

    I want to better understand your schematic for AD8479, specifically regarding the internal circuitry. In the datasheet, it mentions the input resistor with a value of 1 Megaohm and an additional resistor in the feedback loop.

    Could you please confirm whether the resistors in your schematic are the internal resistors or is it an external resistor? Clarity on this matter would greatly assist in my application of the AD8479.

    Looking forward to your thoughts. Thank you!

    Regards,

    Mae

  • sorry for the confusion.

    It is an external resistor. 

  • +1
    •  Analog Employees 
    •  Super User 
    in reply to derekl

    Hello  ,

    The schematic you provided will work, but I noticed a typo which should be corrected to 14V. I also have a concern regarding impedance matching, which the customer may consider. 

    As I mentioned before, the internal resistance of AD8479 is 1M ohm, which contributes to the impedance. I have calculated the impedance for each input, which you can find below. As this is a DC application, the reactance is zero, and the impedance will be equivalent to the resistance. I noticed that the impedance of the first and last inputs is different from the rest, as one side of the input pin is connected to another amplifier. Therefore, I suggest adjusting the resistance of the first and last part of your schematic (green box) to match the rest.

    Let me know your thoughts.

    Thanks,

    Mae

Reply
  • +1
    •  Analog Employees 
    •  Super User 
    in reply to derekl

    Hello  ,

    The schematic you provided will work, but I noticed a typo which should be corrected to 14V. I also have a concern regarding impedance matching, which the customer may consider. 

    As I mentioned before, the internal resistance of AD8479 is 1M ohm, which contributes to the impedance. I have calculated the impedance for each input, which you can find below. As this is a DC application, the reactance is zero, and the impedance will be equivalent to the resistance. I noticed that the impedance of the first and last inputs is different from the rest, as one side of the input pin is connected to another amplifier. Therefore, I suggest adjusting the resistance of the first and last part of your schematic (green box) to match the rest.

    Let me know your thoughts.

    Thanks,

    Mae

Children