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LMH 0031 not working

Muhammad Nouman
Prodigy 20 points
Other Parts Discussed in Thread: LMH0030, LMH0031

I have applied all the voltages properly. The IO pin 6 is giving 3.3V as it is supposed to be, but other than that there's absolute no response. I have verified all the connections. Applied 27Mhz at the Ext clk. Made sure the proper initialization of power i.e. 2.5v is applied after 3.3v. The Control register write flow is working for LMH0030, but LMH0031 is not responding in any way at all.

  • 0
    TI__Mastermind 29655 points

    Hi Muhammad,

    In order to help us diagnose the problem, could we have some more information about the system?

    - Any specific data rates you are running?

    - Schematic/layout of current system?

    - Cable type and length to connect the LMH0030 to LMH0031?

    Thanks,

    Michael

  • 0 in reply to Michael Lu (Santa Clara)
    Prodigy 20 points

    I am trying to use it for SDTV 27, ITU-R BT 601.5, schematics is same as of test circuit in datasheet, but I guess these would be later problems. Right now, the main issue is that it is giving me almost no response.

    I tried to use Built in self test, nothing happened.

    Tried to map FIFO empty flag on IO pin0, didn't get mapped.

    Tried to read registers, it returned absolutely nothing. even the AD9 pin didn't get high as a handshake protocol.

    The Read and write protocol is same as used for LMH0030 and that's working fine. I don't know if I am missing anything. It is giving constant 2.5V on XTALo, pin 61.   

  • 0 in reply to Muhammad Nouman
    TI__Mastermind 29655 points

    Hi Muhammad,

    How are you connected to the LMH0031? Are you using an evaluation module?

    The fact that XTALo is giving a constant 2.5V and not buffering your external 27MHz oscillator seems to imply that something is not working correctly with the clocking or the oscillator in your system. However, we cannot quite diagnose this well without a schematic or BOM. Even if you are using the same schematic as the test circuit in the datasheet, the test circuit leaves out key details, like how the power is being supplied as well as where the signaling and clocking is coming from. Could you please provide your current schematic and BOM to us?

    Thanks,

    Michael