LMK03328: Operation of PDN pin and I2C

Hi Kawai-san,

Q1). Is PDN=Low and software reset (R12.7) exactly the same operation ? I believe both reset would hold the register programmed value.

A1). From data sheet section 10.4.11: Invoking software reset via R12.7 does not re-initialize the registers; rather, the device retains settings related to the current clock frequency plan. Using this method allows for a VCO calibration for a frequency plan other than the default state (i.e. the device calibrates the VCO based on the settings current register settings).

Q2). When user had powered up and programmed the registers, he would need reset for VCO calibration. By toggling PDN pin = High-Low-High, does the user need to throw dummy read command again to have successful I2C communication, too ? (due to following NOTE in the datasheet)

A2). Please see this E2E post: https://e2e.ti.com/support/clocks/f/48/t/658035

Kind regards,
Lane

Hi Lane-san,

Thanks for your comments.

For Q1, what I need to clarify is that,
A). Whether toggling "PDN=High->Low->High" would reset the register value to default or not.
B). Whether the operation of toggling PDN=High->Low->High and toggling softreset R12.7=0->1->0 are exactly the same behavior or not.

For Q2, this is my additional question which I had posted to the E2E : https://e2e.ti.com/support/clocks/f/48/t/658035

I need to clarify that whether user needs dummy read command after VCO calibration or not.

Power up -> PDN=H -> dummy read command -> program registers -> VCO Calibration -> dummy I2C read command required ?? -> Now ready for I2C communication including other I2C devices.

Since, you need to toggle "PDN pin" or "R12.7" to start VOC calibration, I am wondering if you need dummy I2C access for the device to be able to communicate correctly, due to the NOTE which described in the datasheet.

Best Regards,

Kawai

Hi Lane-san and Team,

For soft reset using R12.7, this is the I2C command so user would not need dummy I2C read command after this VCO Calibration.

How about VCO Calibration using PDN pin toggle ?

It would be helpful if you could advise us by 1/29. Customer is waiting for the information to fix software.

Best Regards,

Kawai

Hi Team,

Could you please help us on this topic ? We have many customers considering this device. Please allow us to make sure so that user would not face such problem.

Best Regards,

Kawai

Hi Alan-san,

Thanks for the answer.

I would like to request to modify the "NOTE" information on the data sheet page 52 since the description does not include enough information.

It seems that when I2C accessed with LMK03328 PDN=Low, somehow, other slave device would get stuck in abnormal mode that bus would be pulled down. It could not recover from this mode even when LMK03328 is removed from the I2C bus, required system power cycle (remove LMK03328 and slave device power cycle).

Can you please confirm with your EVM and another I2C device on the same bus ?

Thanks and Best Regards,
Kawai