LMX2595: LMX2595 Programming

Hi Zheej,

You don't need to write all registers unless you want to make it lock to a certain frequency. The key points in that section is the procedure.

1. Vcc power up the device. The internal POR circuitry shall bring the device to a known state. To play safe, we recommend:

2. Write RESET to reset the device. 

From here, the device should be in a known state and if the followings are done in sequence, it should lock.

3. Provide a valid reference clock to the device. If you want to make it lock, you need to provide a valid reference clock here or after step 1 above. If you simply want to test the logic, for example, powerdown the device, the reference clock is not needed. 

4. program all the registers in descending order, from R78 to R0 (FCAL_EN should be equal to 1)

If you are not able to program the device, possible reasons are:

- the device is damaged

- schematic or layout is wrong

- SPI timing is not right

To debug your problem, try this:

1. Vcc power up the device

2. write RESET = 1 (R0 = 0x2412). 

3. write POWERDOWN = 1 (R0 = 0x2411)

Can you power down the device?