Post Go back to editing

HMC1197 Programming

Customer is programming 2 HMC1197 modulators using shared SPI CLK, DIN and DOut with separate SEN lines. They observe that always the second modulator to get programmed either comes up unlocked. or locked with  very noisy output. They have experimented with shutting down the first programmed modulator with no effect on the lock state or noise on the 2nd modulator. The read out of both chips (attached register dumps) indicate only register 11h to be different, This register is read only and no explanation of what it indicates. SPI connections to modulator chips use 33 ohm series resistors to SCLK and MOSI. No pull-up or pull-downs on either signals -- is it required? Please let  me if there are any clues to what the issue might be. Thanks.

Parents Reply Children
No Data