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LMK61E2: Two register values change back to their reset value unexpectedly

Yong Liu1
Prodigy 20 points
Part Number: LMK61E2

Hi Ti，

We bough two pieces of LMK61E2. The first one looks fine in recent frequent tests. The second one was soldered on the similar PCB.

However, the output of the second LML61E2 is unstable. 

After the register value writing, two registers' values change back to their reset values automatically and unexpectedly.

The register R32 changes back to its rest value 0x00，this makes the  denominator 0 in the application of integer N divider.

The register R23 changes back to its rest value 0x20, the required value is 0x28

Once I re-writer the correct value the those resisters, their values change again a few seconds or a few minutes later.

Do you have any idea or clue of the abnormal behavior?

Best Regards!

Wallace

  • 0
    TI__Expert 6140 points

    Hello Wallace, 

    This seems to be a soldering problem with the Vdd pin - the intermittent power it's causing device to power down and on the next power up, it's going back to original EEPROM configuration which obviously had different values from your register programming. 

    Please examine the soldering. If the output current is unstable that would be a direct indicator that it's not making good contact. 

    Thanks and regards,

    Amin