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Some I²C devices like the MCP4728 DAC have a small EEPROM allow programming the I²C address (and other configuration bits). I know that in high volume can be programmed by the vendor, but for low volume prototyping, how are these typically programmed?

  • Are they programmed on the board? If so, how can you configure just one component if there are more than one on the bus that need to be configured and they all come with the same address?
  • Do they need programmed one at a time with all others powered off?
  • Other best practice suggestions would be appreciated!
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2 Answers 2

Reset to default
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The chip has a pin, LDACn, that has a second function of selecting a device for writing the address bits. See the datasheet.

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  • \$\begingroup\$ It does! Thank you for pointing that out: "WRITE I2C ADDRESS BITS: This command is valid only when the LDAC pin makesa transition from “High” to “Low” at the low time of thelast bit (8th clock) of the second byte, and stays “Low” until the end of the third byte. The update occurs after “Stop” bit, if the conditions are met. The LDAC pin is used to select a device of interest to write. " \$\endgroup\$
    – KJ7LNW
    Commented Mar 23, 2021 at 23:44
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There are different ways to go about this, and it is open to you.

If you have an MCU on the board, then use that MCU.

Else, you can make a board jig with an MCU and pogo pins, or perhaps use an Arduino which probably already has the library for the chip.

PCB SMT Manufacturers can do it for you, but you need to provide them the equipment.

Overall, your question seems a bit off, if you need to program them, it means there must be some kind of adjustment to be done, thus something to measure and something to adjust, which would certainly require some test jig.

If it's not the case, then there is probably a circuit you can use instead of a programmable DAC.

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