LMK3000C

Lin,

The maximum temperature of this device is rated in the datasheet is an ambient temperature of +85.

We have also taken into consideration that the die temperature will heat  up hotter when you turn on the device and the outputs.  In other words, the internal die is rated to a higher temperature than +85.

We have also considered the possibility of locking the VCO at -40 C and letting the temperature drift to +85 without reprogramming.

If you are within the operating limits of the device, have you also considered the TCXO or whatever reference is driving it?

If this signal fails, then this will cause our device to lock.

For diagnostic purposes, you can look at the N and R dividers of the LMK03000 to see what the frequency the part thinks it sees at the VCO and TCXO.

Regards,

Dean

If the device is very hot and behavior is not as expected, then you might want to check a few basic things (in addition to what Dean suggested earlier):

• Is the power supply reasonably close to what you would expect based on the figures / guidance in the datasheet?
• Visually inspect the IC / board for shorted pins and improper connections that could cause the IC to malfunction.  Make sure all power, ground pins, and thermal pad are connected properly.
• Are you testing this device on our evaluation board or your application board?  If using our evaluation board, did you provide the correct supply voltages as indicated in the user guide?

Best regards,

Alan