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BQ224610 Layout Questions

Mike Dielman
Prodigy 385 points
Other Parts Discussed in Thread: BQ24610

We are looking at using the circuit layout of the application circuit of the BQ224610 EVM in our product.

But we'd like to change to larger components fo ease of probing and manufacture; mostly changing the 0402 size smt resistors to 0603? or 0805.

Is this okay?  Are there any concerns about moving to larger components with this layout?

 

We'd still follow the layout guidelines per the data sheet as closely as possible, of course.

Also, re the "kelvin" connection for the current sense resistors shown on

p.28 of the data sheet: is this showing a solder connection only at the corners of the resistor?  If there is something with a clearer detail of the connection, that would be great.

We've started schematic capture already, and will be into the layout Monday, so time is of the essence.

  • 0
    TI__Guru**** 150910 points

    I assume the part number is bq24610?  The bq224610 does not exist.

    Yes, it is ok to use larger components.  Try to keep the same relative placement to ensure the same performance.  Since the 0603 parts are twice as big as the 0402 parts, the passives will take up more room.  The key is to spread everything out, keeping it all in roughly the same place as it was.  Don't take 2 or 3 parts out of the area they were in to make room for the larger components--and then replace those 2 or 3 parts just where there is some room left on the board.

    The connection to the sense resistor is a regular kelvin connection.  There are 2 things to remember here.  First, make the connection from the sense trace to the resistor at the resistor's terminals.  Making the connection anywhere else will add extra trace resistance into the measurement and results in basically the same effect at an inaccurate sense resistor.  The second thing is to route the sense traces together as a differential pair.  This will help keep the noise down.

    Here is a screenshot of how this is done on the EVM.

    6746.24610.doc