DS90UB635-Q1: TSER953 & TSER954 CSI2 via header

Hello Cindy thanks for your ongoing help.

Two other FPD questions:

-i2c - we are operating our V3Link parts at 1.8V can the deserilizer running with a core of 1.8V communicate with a i2c host that operates at 3V3? it says the i2c is 3V3 tolerant.

-If I want to read my DS90UB953/4 registers with my EVM I can project the chips with my application process, then disconnect my controller and connect the EVMs MCU and click to read the registors. How do I prevent the ALP from automatically overwriting the registors of the chips once reconnected?

-compatibility: due to availability we are looking to build with the TSER series since we are not automotive and have only one cam per de-serializer. While we can source the TSER953 at distributors, we cannot locate the TSER954, but only the TDES954. Are these two devices compatible with each other. Are these devices functionally equivalent to the DS90UB953/4 (including config registors) aside from temperature range and auto qualification? 

Hi Andrew,

1. All devices using the same I2C bus must use the same I2C voltage. If you are using the 954 EVM, you can use a jumper to select either 1.8V or 3.3V I2C. By default, the I2C I/O thresholds are tied to VDDIO, but you can overwrite this using register 0x0D IO_CTRL in the 954. This voltage is applied to both the I2C and PDB pins.
2. To clarify, are you saying that you read the 953/954 registers using an I2C host, and then you disconnect the I2C bus and connect it to ALP? As long as the devices are not powered off, the registers will remain fixed. Otherwise, when you power the device off then back on, all of the registers go back to the default value. What is being overwritten on ALP? 
3. The V3Link device naming convention has TSER refer to the serializer and TDES refer to the deserializer. The correct pairing is TSER953 and TDES954. The first page of the datasheet will typically reference the compatible devices. These devices are functionally equivalent to the DS90UB953/954, so all programming of registers would be the same.

Regards,

Cindy 

Still a little confused, we can just connect our i2c pull-up to 3.3V (for the target) even if our TSER953 is operating at 1.8V AND we need to update a single control register?

Andrew,

If the TSER953 is operating with 1.8V I2C mode, then the logic thresholds are going to be at 1.8V levels. Meaning that we can not guarantee that it will work correctly with 3.3V I2C (for example VIL threshold may not be met if the I2V bus voltage doesn't swing down to 0V - it could be within spec of 3.3V signaling levels but not within 1.8V). So we always recommend to match the I2C strapped voltage setting of the TSER953 to the bus pull up voltage. 

Best Regards,

Casey 

Hello Casey Can you kindly confirm this configuration is kosher? 

Regarding this level translation is there any difference accross the other V3Link solutions: DS90UB953/, DS90UB635/8?

TSER953 1.8V (all rails)

I2C pull-up 3.3V

I2C for camera 3.3V

GPIO outputs will be 1.8V (I am going to use a FET to invert & level shift)

IDX: 1V (sets I2C address & I2C voltage)

TDES954 3.3V VDDIO, and 1.8V all other rails

I2C pull-up 3.3V

I2C for ISP 3.3V

GPIO inputs are 3.3V

REFCLK, PDB both tied to 3.3V

note: level translator required datasheet pg 52 ". Note that the voltage of VI2C must match the voltage of VVDDIO"