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LMK04828: No outputs

Part Number: LMK04828
Other Parts Discussed in Thread: LMK04821

I am using LMK04828 on a dual site ATE final test board.  With 700MHz/13dBm input at CLKIN1, I didn't see any output at SCLKOUT.  Schematic is attached.  Below are the SPI writes.

    SPI::wspi_lmk(0x138, 0x40);  //VCO mux = CLKIN1
    SPI::wspi_lmk(0x146, 0x10);  //CLKin1_EN = 1


    // Divider of DCLKoutX_DIV
    SPI::wspi_lmk(0x110,0x04);  //S1 FPGA REFCLK_1
    SPI::wspi_lmk(0x100,0x04);  //S1 FPGA REFCLK_2
    SPI::wspi_lmk(0x118,0x04);  //S2 FPGA REFCLK_1
    SPI::wspi_lmk(0x130,0x04);  //S2 FPGA REFCLK_2

    // Output Format
    SPI::wspi_lmk(0x107,0x11);  //S1 FPGA SYSREF = LVDS, REFCLK_2 = LVDS
    SPI::wspi_lmk(0x10F,0x60);  //S1 DUT SYSREF = LVPECL 2000mV
    SPI::wspi_lmk(0x117,0x04);  //S1 FPGA REFCLK_1= HSDS 10mA
    SPI::wspi_lmk(0x11F,0x04);  //S2 FPGA REFCLK_1= HSDS 10mA
    SPI::wspi_lmk(0x127,0x60);  //S2 DUT SYSREF = LVPECL 2000mV
    SPI::wspi_lmk(0x137,0x11);  //S2 FPGA SYSREF = LVDS, REFCLK_2 = LVDS
    SPI::wspi_lmk(0x12F,0x00);  //NC powerdown

    // PowerDown
    SPI::wspi_lmk(0x116,0x30);  //S1 FPGA REFCLK_1
    SPI::wspi_lmk(0x106,0x30);  //S1 FPGA REFCLK_2
    SPI::wspi_lmk(0x11E,0x30);  //S2 FPGA REFCLK_1
    SPI::wspi_lmk(0x136,0x30);  //S2 FPGA REFCLK_2

    // Select SDCLKOUTy input
    SPI::wspi_lmk(0x104,0x20);  //S1 FPGA SYSREF
    SPI::wspi_lmk(0x10C,0x20);  //S1 DUT SYSREF
    SPI::wspi_lmk(0x124,0x20);  //S2 DUT SYSREF
    SPI::wspi_lmk(0x134,0x20);  //S2 FPGA SYSREF

    // Sysref divider
    SPI::wspi_lmk(0x13A, 0x1); //div by 480
    SPI::wspi_lmk(0x13B, 0xE0);

    HSX_helper::StartHsxClk(4, Freq, 13);  //LMK_CLKIN: 13dBm

    WAIT_TIME(100 us);
    SPI::wspi_lmk(0x144, 0xFF);
    SPI::wspi_lmk(0x139, 0x3);

    //power up
    SPI::wspi_lmk(0x02, 0x0);

  • Hi Cindy,

    The schematic is not showed. Could you attach it again?

    About SPI register operation, could you follow up the steps as datasheet recommendation?

    1. Program register 0x000 with RESET = 1.

    2. Program registers in numeric order from 0x000 to 0x165. Ensure the following register is programmed as

    follows: – 0x145 = 127 (0x7F)

    3. Program register 0x171 to 0xAA and 0x172 to 0x02.

    4. If using LMK04821, program register 0x174. LMK04828 could skip it.

    5. Program registers 0x17C and 0x17D as required by OPT_REG_1 and OPT_REG_2.

    6. Program registers 0x166 to 0x1FFF.

    For registers value, please use TICS Pro software to generate what you wanted.

    Regards,

    Shawn