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ADF4118 not powered up

I have fabricated the PLL according to the datasheet, I have also checked the design accordingly for any open or short circuit errors. As soon as I switched on the power supply and apply it to Vdd the chip is not drawing any current as if it is open-circuited. What may be the reason? do we require to SPI even to power up the IC? 

  • Hi, 

    All supply voltages should be brought up before placing any logic on the SPI lines. 

    Before diving into the list below check the CE pin and be sure it is pulled high. A logic low on CE powers down the device and tri-states the CP. Pulling it high will power up the device depending on the status of the power down bit PD1 (PD2 doesn't matter for power up). Refer to the truth table for CE & PD bits on page 17 of the DS. 

    Note that the datasheet appears to have an error as it refers to the power down bit as 'F2' in the pin descriptions instead of PD1. 

    If all of the above is o.k. then:

    1) Using a board with no device mounted to it verify continuity for supply and gnds (sounds like you may have done this but might repeat on a board without a part mounted to it to verify the board / fab). 

    2) Verify current compliance setting on your supply (if set to low voltage will be pulled down and part won't turn on). Do you get supply voltage prior to connecting to your board? What does the supply measure after connecting it to our board?  (Can also use an evaluation board if you have one). 

    3) Verify that you are getting the expected voltage for AVDD and DVDD at the pins of the device. Verify ground connections at the device pins including AGND,DGND and CP GND. 

    4) If everything looks good may have to replace the device as it may have been damaged during board assembly. Be sure to follow good ESD handling practices and don't exceed peak reflow temperatures or subject to extended peak temperatures for an excessive time. 

    Best Regards, 

    Marty 

  • Thank Sir, In the meantime, I have also debugged the problem. The power of the device will not be turned on until and unless we place the SPI pins. Even if the CE pin is pulled high. After placing the SPI pins with the required bits the PLL is turned on with the required current rating, although the current ration is bit high i.e around 12 mA.