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LMX2592: Excessive power consumption

Bence Cseppento
Prodigy 20 points
Part Number: LMX2592

Dear Experts,

I am configuring az LMX2592 as a demonstrative device at the university. I intend to use it with a single-ended 10MHz quartz reference (3.3Vpp) for which I am using a 10dB attenuator pad and I need only one single-ended RF output so the output B pins are left floating. I have also placed 12k pull-down resistors on the SDI, SCK, CE, MUXOUT, CSB pins. Other than these, I have followed the reference design at the end of the datasheet, mostly for the layout as well.

However, when I apply the power supply with a current threshold of 50mA while disabling my reference and pulling CE to low (thus current consumption should be 7mA) the supply current maxes out at 50mA and the supply voltage drops to 1.4V. I hope I have not damaged the chip, if the current threshold was set higher I think it would have overheated.
Do you have any tips for debugging? I have repeatedly checked my design and also the soldering with a microscope and a multimeter numerous times, but I can't put a finger on it.

Thank you in advance for your response and your time!
Regards,
Bence Cseppentő

  • 0
    TI__Guru** 107390 points
    Hi Bence,

    First, disconnect the reference clock and pull CE LOW.
    Vcc power up the device.
    If you still have over current issue, then I think there must be something wrong with the soldering or the schematic.
    When CE is LOW, all the IO will be pulled low, check if you have connected these IO to some voltage sources.