SN65LV1224B: extending transmission length by SerDes chip

yuqing xiao

Part Number: SN65LV1224B
Other Parts Discussed in Thread: SN65LV1023A

I want to transmit 10 Bits 10MHz LVTTL data over 130-meter shielded twisted cable and I created schematic as attachment, is the schematic ok for this application? J1 and J3 on schematic is RJ45 jack, and I will add CAT5e STP cable between J1 and J3 for testing.

3223.LVDS.pdf

over 4 years ago

0 David (ASIC) Liu over 4 years ago

TI__Guru**** 177151 points

Hi,

1. The LV1224B input is AC coupled, but you still need to set its common mode voltage. Please see this app note on AC and DC coupling the LVDS, https://www.ti.com/lit/an/slaa840/slaa840.pdf.

2. RCLK is not connected, RCLK is used to strobe ROUTx. Please see figure 14 at the datasheet

3. Do you want to provide a test point for the LOCK signal?

Thanks

David

0 yuqing xiao over 4 years ago in reply to David (ASIC) Liu

Prodigy 20 points

Thanks for your help, David.

which connection from document is recommended by you? figure 3 and figure 4?

from this document, coupling capacitor is removed from input of receiver.

0 David (ASIC) Liu over 4 years ago in reply to yuqing xiao

TI__Guru**** 177151 points

Hi,

Either Figure 3, 4, or 5 in the app note can set the receiver input common mode voltage to 1.2V.

Thanks

David

0 yuqing xiao over 4 years ago in reply to David (ASIC) Liu

Prodigy 20 points

Hi David,

do you know replacement for SN65LV1023A/SN65LV1224B? it looks L/T is very long.

0 David (ASIC) Liu over 4 years ago in reply to yuqing xiao

TI__Guru**** 177151 points

Hi,

Unfortunately I don't have a replacement for SN65LV1023A/SN65LV1224B, please work with our TI sales to the L/T.

But looking at the SN65LV1023A/SN65LV1224B TI.com website, we still have some units in inventory.

Thanks

David

0 yuqing xiao over 4 years ago in reply to David (ASIC) Liu

Prodigy 20 points

How I choose proper frequency for PCLK?

is transmit rate of serializer fixed value no matter how much frequency of PCLK feed?

if possible I want to extend cable length of transmit by reducing transmit rate.

0 David (ASIC) Liu over 4 years ago in reply to yuqing xiao

TI__Guru**** 177151 points

Hi,

Are you referring to the TCLK?

For TCLK, the serializer transmits serialized data and appended clock bits (10+2 bits) from the serial data output (DO±) at 12 times the TCLK frequency. For example, if TCLK is 66 MHz, the serial rate is 66 × 12 = 792 Mbps. Because only 10 bits are input data, the useful data rate is 10 times the TCLK frequency. For instance, if TCLK = 66 MHz, the useful data rate is 66 × 10 = 660 Mbps. The data source, which provides TCLK, must be in the range of 10 MHz to 66 MHz.

Thanks

David

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SN65LV1224B: extending transmission length by SerDes chip