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DP83869HM: DP83869HM

li shu
Prodigy 100 points
Part Number: DP83869HM
Other Parts Discussed in Thread: AM3358, DP83869, DP83869EVM, USB-2-MDIO

Hi,

question 1: the DP83869HMRGZT pin43 is the RESET_N, I don't see the WPU (internal pull up) for this pin, so do I need adding a external pull up resistor( which connect to the VDDIO) to this pin?

question 2: this chip has two VDDA2P5 pins , three VDD1P1 pins, and two VDDIO pins, each pin should add the 1uF and 0.1uF decoupling capacitors, but in the datasheet page 109, Figure 114,DP83869HM power pins.docx, it showed there are three VDDIO pins, and four VDDA1P1 pins, can you explain why?

thanks,

Li

  • 0
    TI__Expert 5425 points

    Hi Li,

    Question 1:

    Refer to section 9.5.3 of the datasheet on how the RESET_N pin functions. There is a diagram of how the pin should be connected as well.

    Question 2:

    The diagrams showing power supply configuration are incorrect. There are only two VDDIO pins and three VDDA1P1 pins, as described in the pin function table. The decoupling capacitors should be the same. Thank you for bringing this error up, and we will fix it in the next version of the datasheet.

    Regards,

    Adrian Kam

  • 0 in reply to Adrian Kam
    Prodigy 100 points

    Hi,

    thanks for quick reply, but to question 1, I still confused, because my design is one of GPIO pin of the CPU(like AM3358) would connect with this RESET_N pin, and the AM3358 will send the control signal to reset this DP83869 chip if necessary. actually my question is two parts:

    part 1. if I don't add the external pullup resistor on the RESET_N pin, when the power up, how this chip get into reset(this pin is NOT internal pullup pin), this is hardware reset situation.

    part 2. if the AM3358 want to reset the DP83869 chip( software reset situation), but how could this chip be reset if there is no external pullup resistor ?

    thanks,

    Li

  • 0 in reply to li shu
    TI__Expert 5425 points

    Hi Li,

    To address both of your questions at once, there is an internal pull-up on the RESET_N pin. It is stated in the Pin States table following the Pin Functions table. You can simply connect the GPIO pin of the CPU to the RESET_N pin, but the RC circuit shown in the datasheet should be kept there in parallel. As a result, no external pull-up resistor is required.

    Regards,

    Adrian Kam

  • 0 in reply to Adrian Kam
    Intellectual 460 points
    Hello.
    The block diagram of the test system is shown below.
    　PC_A（100Mbps,Full-Duplex） - Ethernet Cable - DP83869EVM - Coaxial Cable - DP83869EVM - Ethernet Cable (100 BASE-TX) - PC_B（100Mbps,Full-Duplex）
    - The NIC setting for PC _ A and PC _ B is set to 100 Mbps (Full-Duplex).
    - Communication between PC _ A and PC _ B is evaluated using a tool called Iperf.
    - An Ethernet cable is used to connect the PC to the DP 83869 EVM.
    - A coaxial cable is used to connect the SON/SOP/SIN/SIP terminals between the DP 83869 EVM.
    With the [USB-2-MDIO software], write the register of DP 83869 EVM as follows:
    Communication between PC _ A and PC _ B was possible with 100 BASE-FX.
    　01DF 0005
    　0000 1140
    　0010 5048
    In order to simplify the system, I would like it to function as a 100 M Media Convertor Mode with only strap resistance without writing to registers. Is that possible?
    Thanks.
  • 0 in reply to user6150189
    Intellectual 460 points

    The above is a mistake. I'm sorry.

  • 0 in reply to user6150189
    TI__Expert 5425 points

    Closing this thread.