DS90UB954-Q1: 933 pair with 954

Huang David

Intellectual 320 points

Part Number: DS90UB954-Q1

Hi Expert,

933 is adapted to input clock frequency, so the speed in the cable is not fixed, and it is changed based on the input.

95x the speed in the cable is fixed no matter what ever input speed.

So if 933 connected with 954, can it work? and how it work?

Thanks

Best regards,

David

over 3 years ago

0 Darrah Merillat over 3 years ago

TI__Mastermind 26610 points

Hi David,

Thank you for your question. The 954 is compatible with the 933. When using these two devices the 954 will need to be in the RAW functional mode to be backwards compatible with the 933. The devices are able to support a range of frequencies (to a max of 100 MHz) and the resulting data rates. You can find more details on this mode and how the data rates are calculated in section 7.4.2 of the datasheet.

Regards,

Darrah

0 Huang David over 3 years ago in reply to Darrah Merillat

Intellectual 320 points

Hi Darrah,

Thanks for your feedback. When 954 pair with 933, when the input clock to 933 change, what about the data rate over the cable? is it fixed or also changed according to the input clock?

Best regards,

David

0 Darrah Merillat over 3 years ago in reply to Huang David

TI__Mastermind 26610 points

Hi David,

The rates are dependent on the chosen mode and the input clock.

Regards,

Darrah

0 Huang David over 3 years ago in reply to Darrah Merillat

Intellectual 320 points

Hi Darrah,

Thanks for your feedback. Clear about this.

For the case if 953 connected with 954, but the input sensor bandwidth is very low, for example 1Gbps, will the cable data rate be fixed 2G/4G ?

If so, this looks like a waste of bandwith, why not use the dynamic scheme based on the input clock?

Best regards,

David

0 Darrah Merillat over 3 years ago in reply to Huang David

TI__Mastermind 26610 points

Hi David,

The 953/954 also have different modes which would impact exactly how the devices function. For example, using CSI-2 Synchronous mode the line rates depend on a reference clock that is passed to the 953 from the 954 via the backchannel, but Non-Synchronous mode the line rates depend on an external clock supplied to the 953. The RAW mode is dependent on the PCLK. You can reference Section 7.4 (Device Functional Modes) of the datasheet for more details.

Also keep in mind that the forward channel includes other signals such as I2C and GPIO in addition to the data from the sensor.

Regards,

Darrah

0 Huang David over 3 years ago in reply to Darrah Merillat

Intellectual 320 points

Hi Darrah,

Thanks. One more questions, want to consult with you that what factor limit the the 80Mbps ? why not to 60Mbps or lower?

Thanks

Best regards,

David

0 Darrah Merillat over 3 years ago in reply to Huang David

TI__Mastermind 26610 points

Hi David,

The minimum/maximum values in the datasheet represent the range that the device has been designed and verified to support. The device is not able to properly lock or recover the clock at rates below 80 Mbps.

Regards,

Darrah

0 Huang David over 3 years ago in reply to Darrah Merillat

Intellectual 320 points

Hi Darrah,

Thanks for your feedback. So another questions is if the MIPI input is 80 Mbps, and 953-954 data rate is 2G or 4G, what about other 1.98G or 3.98G data come from?

Best regards,

David

0 Darrah Merillat over 3 years ago in reply to Huang David

TI__Mastermind 26610 points

Hi David,

The FPD-link channel includes additional overhead and signals in addition to the data that is being serialized/deserialized. This can include data such as GPIO, I2C transactions, control bits, etc.

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DS90UB954-Q1: 933 pair with 954