SNLA267A March 2019 – June 2019 DS90UB953-Q1 , DS90UB954-Q1 , DS90UB960-Q1
The I2C SDA and SCL pins on the 954 and 953 are open-drain and require pullup resistors for operation. External 1-kΩ to 4.7-kΩ pullup resistors to the digital supply voltage—VDDIO on the 954 or VDDD on the 953—are recommended per I2C interface standards. Note that I2C communication to image sensors or microcontrollers may require different or the same digital supply voltages.
If the digital supply voltages are different between devices, I2C voltage level shifters are recommended to translate between any of the 1.8-V, 2.5-V, 3.3-V, and 5-V logical signal levels necessary for communication. For example, the TCA9406 is a 2-bit, bidirectional I2C and SMBus voltage-level translator with an output enable (OE) input. It is operational from 1.65 V to 3.6 V on the A-side—referenced to VCCA—and from 2.3 V to 5.5 V on the B-side—referenced to VCCB.