SNLS707 February 2023 DS90UB635-Q1
PRODUCTION DATA
When initializing the communications link between a deserializer hub and a DS90UB635-Q1 serializer, the system timing will depend on the mode selected for generating the serializer reference clock. When synchronous clocking mode is selected, the serializer will relock onto the extracted back channel reference clock when available, so there is no need for local crystal oscillator at the sensor module. The initialization sequence follows the illustration given in the Initialization Sequence: Synchronous Clocking Mode.
To allow for a quicker system bringup time, it is recommended to program the I2C watchdog timer speedup, by setting 0x0A = 0x12, before trying to access remote I2C target devices attached to the SER through the back channel from the deserializer. This will ensure a faster remote sensor access time even if the serializer I2C bus experiences unexpected noise during power up of the sensor module.