LMX2594: Wake-up time from sleep mode

Marco Pilas

Part Number: LMX2594

Tool/software:

Hello,

1. I would like to know what will be the total "wake up" time from power down state to a lock signal state

This time should include all the steps to lock the signal to a wanted frequency except the lock time that depend on the loop filter design (I will add this time to your answer)

2.What registers need to be loaded at this procedure?

3. On the data sheet page 40 clause 7.5.1 "Recommended Initial Power-Up Sequence" it is written that we need to wait 10ms after programing the registers, does it refer also to "wake up" time from sleep mode (not first-time of power-up)?

Best Regards,

Marco.

over 2 years ago

0 vicente flores prado over 2 years ago

TI__Mastermind 32152 points

Hi Marco,
1. Power on time of output buffer should be instantaneous, the time taken to write to the register will dominate.

2. Registers should be programmed in descending order:

3. No, this refers to the first time (initialization) only.
The 10ms requirement is to ensure LDOs settle before the next VCO calibration.

Regards,

Vicente

0 Marco Pilas over 2 years ago

Prodigy 40 points

Hi,

Thanks a lot for your fast response. Can you estimate the time it will take to write to the registers

Regards,

Marco

+1 vicente flores prado over 2 years ago in reply to Marco Pilas

TI__Mastermind 32152 points

Hi Marcos,
Programming time depends on your SPI write speed.

Maximum SPI write speed is 75MHz.

For example if you have already initialized the device and wish to change output frequencies, this involves editing 3 registers - utilizing the maximum SPI bus speed of 75MHz these 3 writes can be accomplished in ~3us.

Regards,

Vicente

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LMX2594: Wake-up time from sleep mode