Dear All,
I have implemented a LMX2492 PLL IC in a custom made test board and I wanted to verify that the IC is correctly soldered and powered on, so I powered it on with a 3.3V power supple and I measured the current output of said supply, expecting to see somewhere around 3mA of current draw from the IC when it is powered on, as it starts in a powerdown state. To my surprise, the current draw from the IC is 0mA! I need to mention that the IC is completely isolated while powered on, that is, there is no loop filter attached (nor VCO, of course) and there is no REF input signal (open circuit in both REF and REF* pins). I wanted to know if there is some instance in which the current draw would be 0mA when turned on (like an overvoltage protection, power source so noisy it de-stabilizes the PLL IC somehow or any other possible source for this outcome). I also want to know if it is normal that the impedance measured between all VCC pins and ground is around 70kOhm when the IC is turned off.
Kind Regards,
