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LMK04616EVM: No Output from EMV Board

Part Number: LMK04616EVM
Other Parts Discussed in Thread: USB2ANY, , LMK04616

I received a new LMK04616EVM and have it configured using the USB2ANY module and the TICS Pro. The silicon ID comes up as LMK04616, 6: Dual Loop PLL, PG2p0, 1, 20744.  However I am not seeing any signals at the output of the device even using the default setup configuration. All appear to be off. I at least expect to see the external VCXO at the OSCout but only see a ground potential with no signal, even at the chip side of the DC blocking cap, C31. I can see a 122.88 MHz signal at the VCXO output. However neither this frequency nor the tune line change when applying the CLKin signal to PLL1. I have measured all power to the chip and that appears fine (default values). I have also re-checked all the default switch settings on the board. I note some things that may be unusual. During register read back some registers will say similar things to, "Read back Register R0x93 as value 0x009300 was 0x009380 XOR difference = 0x000080." Also when checking status I note a message, "Readback, forcing bits failed, USB2ANY switch connected?" However, the USB2ANY comes up as connected when I look at the USB communications menu and the light on it will flash when identifying it. 

Looking into this a bit farther I measured good signals at JU1 pins 4 (SDIO) and 8 (SCL) when trying to communicate with the LMK04616 via TICS Pro. However with S4B closed the SDIO signal is loaded and does not appear on the S4 side of R74 - LMK04616 side of the SDIO path. Measuring the resistance from TP8 to GND I see about something in the 100 ohm range. This may be the problem. Bad LMK04616, or stuck in the O mode?   

  • Hello Wade

    Sorry to here that the EVM is not working.
    Have you toggled the RESETN pin before loading the configuration? This you can do from the TICSpro->User Controls->Program Pins.
    Can you please crosscheck all the DIP switches and the Jumper and verify against the default configuration specified in the EVM user guide? Here is the link to the userguide:

    www.ti.com/.../snau203.pdf

    Best regards
    Puneet
  • Hello Puneet:

    Thank you. I checked the RESETN box under user controls and now I see output from the OSCout pin at 122.88 MHz. I also see data at the SDI-SDIO line. The startup instructions in snau203.pdf do not say to set this explicitly in the quick start section 1. Should the RESETN box remain checked at all times? I see a reference to the RESETN in figure 2. However, it is somewhat confusing as to what is being done there.

    Regards,

    Wade

  • Hello Wade

    The RESETN box there directly controls the RESETN pin. If the box is ticked, that means RESETN is HIGH and if unticked, then the DEVICE will stay in reset state. Please refer to the LMK04616 datasheet page 49 "Figure 49. Simplified Power-Up Sequence".

    Best regards
    Puneet