SPI Open Mode Selection for HMC704LP4E

Document created by analog-archivist Employee on Feb 23, 2016Last modified by analog-archivist Employee on Aug 10, 2016
Version 2Show Document
  • View in full screen mode

I would like to control HMC704LP4E in serial open mode but cannot see how to
assign a chip address to the PLL. There are no hardware pins or registers to
set it up. Would you please advise.


HMC704LP4E supports two SPI protocols- Open Mode and HMC Mode. This mode
selection occurs after the power-up and POR ( Power-On-Reset ). Approximately
450us after power-up the part will enter SPI mode selection and wait for a
rising edge on either SEN (HMC mode) or SCK (Open mode). 
Mode selection is determined by which SPI signal rising edge occurs first after
power supply voltages are applied (SCK before SEN = Open SPI mode; SEN before
SCK = HMC SPI mode).  SPI mode selection must occur every time the power supply
voltage is applied. 
I am attaching a good application note for your reference.