DS90UB935-Q1: Lane Data rate

ALPHONSA YOHANNAN

Part Number: DS90UB935-Q1

Hi Team,

1. I would like to Know that if I am not using clockout of serializer whether I can use synchronous or non synchronous external clock mode?

2. Whether there is any limitation in using serializer and deserializer as shown below. Especially I would like know whether my serializer 2 will support a 1MP/60FPS (12bpp) data on 2 lanes in non synchronous internal clock mode?If not if I am replacing serailizer 2 with DS90UB953 whether I can use the below configuration?

3. What is the maximum CSI 2 data rate at one lane of DS90UB935-Q1 serializer in non synchronous internal clock mode? Is it 1.632Gbps/4 = 408Mbps(25.5MHz *64 = 1.632Gbps Ref:Datasheet Table 6) ?

Thanks & Regards,

Alphonsa

over 3 years ago

0 Casey McCrea over 3 years ago

TI__Guru* 98615 points

Hello Alphonsa,

1. Either clocking mode is supported

2. This topology is supported.

3. 800Mbps is the max lane rate, but the max total CSI-2 bandwidth for 935 is 2.528Gbps vs. the 3.3Gbps of 953

Best Regards,

Casey

0 ALPHONSA YOHANNAN over 3 years ago in reply to Casey McCrea

Prodigy 100 points

Hi Casey,

Thanks for you reply.

I have one more doubt that if my serializer 935 is connected to camera and I am not using clkout of serializer in synchronous mode, how the CSI2 clock coming to serializer and reference clock synchronization happens?

Best Regards,

Alphonsa

0 Casey McCrea over 3 years ago in reply to ALPHONSA YOHANNAN

TI__Guru* 98615 points

Hello Alphonsa,

There is no synchronization requirement between CSI-2 data and CLKIN to the serializer

Best Regards,

Casey

0 ALPHONSA YOHANNAN over 3 years ago in reply to Casey McCrea

Prodigy 100 points

Hi Casey,

Thank you.

It means that if I am selecting 25MHz as reference frequency my CSI2 bandwidth will be upto 3.2Gbps( 25MHz * 128) but actual CSI data rate may be 3Gbps or something less than 3.2Gbps.

Best Regards,

Alphonsa

0 Casey McCrea over 3 years ago in reply to ALPHONSA YOHANNAN

TI__Guru* 98615 points

Hello Alphonsa,

Right, for 935 the max aggregate CSI-2 BW is 2.528Gbps. Each individual lane may go up to 800Mbps - for example you may have a system where only 2 lanes are used which would be ~1.6Gbps if each is at 800Mbps but the total should be less than 2.528Gbps. If you use 953, it can support all the way up to the max 3.2Gbps total BW (800Mbps*4 lanes)

Best Regards,

Casey

0 ALPHONSA YOHANNAN over 3 years ago in reply to Casey McCrea

Prodigy 100 points

Hi Casey,

I have done the calculation based on datasheet of 935 as shown below. If I want to operate in maximum CSI2 bandwidth of 935(2.528Gbps) what is reference frequency I have to take?

Thanks & Regards,

Alphonsa

0 Casey McCrea over 3 years ago in reply to ALPHONSA YOHANNAN

TI__Guru* 98615 points

Hello Alphonsa,

What is your desired clocking mode? Synchronous or non-synchronous?

Best Regards,

Casey

0 ALPHONSA YOHANNAN over 3 years ago in reply to Casey McCrea

Prodigy 100 points

Hi Casey,

Desired clocking mode is Synchronous mode.

Best Regards,

Alphonsa

0 Casey McCrea over 3 years ago in reply to ALPHONSA YOHANNAN

TI__Guru* 98615 points

Hello Alphonsa,

For this clocking mode you can use 23-26Mhz REFCLK and the standard "50Mbps" back channel rate - any setting in that range can give you the full 2.528Gbps bandwidth

Best Regards,

Casey

0 ALPHONSA YOHANNAN over 3 years ago in reply to Casey McCrea

Prodigy 100 points

Hi Casey,

So I need not worry about reference frequency in synchronous mode and asynchronous mode with internal clock. Whatever reference I am taking in these modes I can operate upto maximum CSI2 bandwidth. Calculations are needed only in non synchronous mode with external clock.

Thanks & Regards,

Alphonsa

0 Casey McCrea over 3 years ago in reply to ALPHONSA YOHANNAN

TI__Guru* 98615 points

Hello Alphonsa,

You just need to ensure that the max available BW for CSI-2 is above 2.528Gbps depending on which clock mode you are in. For example in synchronous mode with 50Mbps back channel, the max theoretical CSI-2 bandwidth would be 25*128 = 3.2Gbps (but limited on 935 to 2.528Gbps)

If you use synchronous half rate mode with 25Mbps back channel, then the max CSI-2 bandwidth is 1.264Gbps, not the full 2.528Gbps.

The same type of thing goes for non-synchronous modes

Best Regards,

Casey

0 ALPHONSA YOHANNAN over 3 years ago in reply to Casey McCrea

Prodigy 100 points

Okay I understood.

Thank you Casey for your support

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DS90UB935-Q1: Lane Data rate