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Configuring CDCE18005 to run with eternal supplies only after programming the EEProm

Paul Redder
Prodigy 30 points
Other Parts Discussed in Thread: CDCE18005

I have a CDCE 18005 EVM board. I have programmed the EEprom and I cannot get the board to run without plugging in the USB cable to a PC running XP and having the PC configuring the USB port. I need to use the EVM in a stand alone application which won't support a PC being nearby. I have tried various external power supply configurations, to no avail. The EVM still will not operate without configuring the USB port. Please advise.

Thanks in Advance,
Paul

  • 0
    TI__Expert 5325 points
    Hello Paul,
    the EVM is not designed for self-sufficient operation. The user guide of the EVM (www.ti.com/.../scau025) contains the schematic.
    The TUSB3210 microcontroller is directly connected to the CDCE18005. The microcontroller 3.3V supply is derived from the USB 5V rail. Only the CDCE18005 DUT can be sourced from an external supply for test purposes. The control pins are all driven by the microcontroller as well as the fet switches for the LVPECL output load.
    When USB is unconnected the microcontroller is in an undefined state. It could interfere with the device. The easiest way is to use the external 5V option and power everything. When you want to exclude the TUSB3210, please blue-wire the enable of the TPS U3 part or use external pwoer supply.
  • 0 in reply to Patrick Kammermayer
    Prodigy 30 points

    Hi Patrick,

    I tried your recommendation yesterday and the unit did power up, but the configuration didn't load from the EEprom. Per the schematic, the PSU_EN pin is an active low pin. Before I disconnected the USB cable, I wrote the configuration to the EEprom and locked the EEprom but, it still didn't come up. . Please advise.

    Thanks in advance,

    Paul

  • 0 in reply to Paul Redder
    TI__Expert 5325 points
    Hello Paul,
    there is one more thing to consider: there is a combination of the control pins required, so that the EEPROM pushes the content to the registers. Please refer to the latest data sheet (SCAS863B) on page 30. SPI_LE pins needs to be at HIGH level while the POWERDOWN! pin sees a rising edge (this rising edge should be faster than 4ns for 20%..80%). The internal pull-ups are only good to avoid unwanted resets in operation. But for the correct sequence you may have to add pull-ups or MCU-control signal in the correct order, so that the device loads the settings.

    Best regards,
    Patrick