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ADuM3160 configuration

Hi everbody,I'm using adum3160 for isolate the PC and controller board, iCoupler ADuM4160/ADuM3160 USB Isolator Evaluation Board as reference, it's many confused about the PIN, configurated as high level but without response,no much better if LOW.

configuration arguments:


VBUS1 : 5V


VDD1: 3.31V

PDEN: 3.31V(connect with VDD1 directly)

SPU: 3.31V(connect with VDD1 directly)

D+,D-, always low.


VBUS2 : 3.3V

GND2: Board GND

VDD2: 3.3V(connect with VBUS2 directly)

SPD: 3.3V(connect with VBUS2 directly)

PIN: 3.3V(connect with VBUS2 directly)

D+,D-, always low.

I'm confused about PC with no response if pull up PIN, and I found that D+(upstream) pulled up to 1.5V if SPD configurate as LOW and SPU configurate as HIGH. it not allowed...

  • Hello Jie,

    The PIN function allows the pullup to be applied to the upstream port under the users control.  The SPU pin will determine which upstrealm line the pull-up is applied to, as well as the buffers timing characteristics.

    Your summary of the voltages, (thank you, that helps a lot), says you are configuring this part to be Full speed so the D+ line should be pulled high to the Idle J condition when there is not active communication by the pullup.  Since this line is sitting at 1.5V, I would look for somthing loading down the line.  If the line is not pulled high, then it probably looks like D+ and D- are both low, which the PC will interpret as an open cable and enumeration will not start.

    For Full speed operation SPU, SPD and PIN should all be ~3.3V, and D+ should be pulled close to 3.3V.

    Are these voltages measured with the ADuM4160 connected to a host port, or is this for an open connector?  Does the USB port on the PC work properly when the ADuM4160 is not used?  How are you powering the downstream side of the ADuM4160?

    Best Regards,


  • Hello MSCantrell,

    Thanks a lot for your consideration firstly.

    These voltages measured with the ADuM3160 connected to a PC, there is no problem of PC USB port. UD+ or UD- are sitting at 1.5V only if SPD is low and SPU is high and without loading,it's a invalid status,but it's the only change on UD lines.

    schematic as following:

    I had test PIN with high or low level but there is no change of D-,D+.

    Then, connect with PC USB port, microcontroller found this connection through LPC175X_USB_BUS,and pull up PIN to 3.3V, nothing changed with UD or DD, nothing happened with PC.

    Also I had tried to power the downstream with a external +5V,just same as the iCoupler ADuM4160/ADuM3160 USB Isolator Evaluation Board, DD+ pulled up to ~3.0V by the loading which is a USB slave device, no change of the UD lines.

    I don't know what's the reason of pull-up off working. Even PC can't find the device insert.Could you give me some suggestion of this schematic or some debug reference.Thanks a lot!

    Look forward to your reply.

    Best wishes!

  • Hello Jie,

    I just went onto the bench to test out your issue with an evaluation board.  I think your problem is that you are not pulling up DD+.  The downstream bus segment requires a pull-up on the DD+ line which should be supplied by your micro.  The PIN function is doing its job, connecting and disconnecting the pullup on the upstream side, but since the DD+ line is low, it is actively driving the low present at DD+ to the output, so you can't see a change. Please make sure that the pullup required by the micro is installed and the micro should enumerate.

    Best Regards,


  • Hello MSCantrell,

    I had test again as your suggestion, that's the reason of all the problem, add one pull-up resistor and then enumeration successfully!

    Thank you very much!!!

    Best wishes!!!