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AD9542 Eval Board I2C jumper settings

Category: Hardware
Product Number: AD9542

Hi Petre,

I am trying to communicate with the AD9542 on the eval board using an external I2C master. However, I'm confused by the table in the wiki which appears to be in conflict with the schematic:

I feel for I2C operation, I should be making P605 1-2 / 5-6 / 8-9 to match Table 68. Is the wiki incorrect? I checked on AD9544 and AD9545 which seems to be the same.

I have removed P506, P507 and P508 and I'm connecting the external I2C master via P512. Anything else to do?

Thanks, Steve

  • HI,

    The table 4 from the wiki refers to how to connect the USB chip to the AD9542. You are right that if you have your own controller and want to manage the AD9545 through I2C, you need to use the P512 connector. Take out P506 and P507, so you take out any influence of the USB chip. 

    You need to have 1K pull ups on  the SDA and SCL lines between the controller and the AD9542 because the AD9545 rev C data sheet does not state there are any internal pull ups on the AD9542.

    Then, you need to manipulate M4, M5 and M6 pins as follows:

    • M4 must be connected to VDD for the AD9545 to use I2C
      • P605 M4 jumper between 1 and 2 (middle pin and VDD)
    • M5 and M6 pins must be connected to GND, so the AD9545 has the I2C address 0x48
      • P605 M5 pin jumper between 5 and 6 (middle pin and GND)
      • P605 M6 pin jumper between 8 and 9 (middle pin and GND)

    Set M5 and M6 function of what AD9542 I2C address you need. I considered them being connected to ground.


  • Hi Petre, I now want to avoid using a 3.3 to 1.8 level shifter for the external I2C master.

    It seems possible if I follow the all but the first step in the wiki for powering directly from the ADP2384A:

    • [DO NOT] Install P802 (sets switcher output voltage to 1.8 V)
    • Install P712/P728 (connects switcher output to VDD_DUT_EXT & VDD_DUT_IO_EXT)
    • Change P704/P725/P727 to pins 2/3 (connects VDD_DUT & VDD_DUT_IO/VDD_MPIN to VDD_DUT_EXT & VDD_DUT_IO_EXT)
    • Change P701/P721/P729 to pins 2/3 (disables LDOs that are being bypassed)

    Would this work?

    Thanks, Steve

  • Luckily, I did not do this and spotted the error of my ways (VDD is 1.89V max). VDDIOA and B are OK at 3.3V.

    So, I made jumpers P712, P728 (linking SW_OUT @ 3.3V, to VDD_DUT_EXT and on to VDD_DUT_IO_EXT) and swapped P725 and P727 to pins 2-3 to make VDDIOA and VDDIOB link to VDD_DUT_IO_EXT.

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