DS90UB913/914 with LVDS repeater

Patrick Chen

Other Parts Discussed in Thread: DS25BR100

Hello

Below is customer topology. They will use DS25BR100 to enhance cable distance by FPD-link. DS90UB913 is transmitted I2S signa to DS90UB914 to drive speaker but they couldn't receive I2S data with DS25BR100. If bypass DS25BR100, customer will receive data successfully. Some questions as below. If any, please help advice. Thank you.

Q1: 914 can lock PCLK 24.576MHz normal but can get normal data now. what is possible root cause?

Q2: They use 5m cable to test now. Any suggestion for cable length on below topology?

Q3: Is DS25BR100 suitable to use for enhance signal on Ser/Des structure?

Patrick

over 9 years ago

0 Lee Sledjeski over 9 years ago

TI__Mastermind 43795 points

Hi Patrick,

General purpose LVDS devices are not compatible with the back-channel communication techniques of the 913 and 914. The I2C link is bi-directional and LVDS devices will only transmit in the forward direction. Without the I2C backchannel data the DS25BR100 is suitable to extend the transmission distance.

Regards,

Lee

0 Prescott Siao over 9 years ago in reply to Lee Sledjeski

TI__Intellectual 2220 points

Hi Lee,

As I know, the input of 914 is CML but the output of DS25BR100 is LVDS.

Is the LVDS compatible with the CML?

Thanks.

Regards,

Prescott

0 Lee Sledjeski over 9 years ago in reply to Prescott Siao

TI__Mastermind 43795 points

Hi Prescott,

The key interface specifications for differential signals are input/output common mode and differential amplitude.

Since the LVDS and CML devices will be AC coupled, only the LVDS amplitude needs to be considered. The LVDS outputs have roughly the same peak-to-peak VOD amplitude as the 913 so there is no issue with interface.

The LVDS outputs of the DS25BR100/110/120 can be AC coupled without any issues.

Regards,

Lee

0 AlexanderSt over 8 years ago in reply to Lee Sledjeski

Prodigy 10 points

Hi Lee,

You said general purpose LVDS devices are not compatible with the back-channel communication techniques. Is there a device that would allow repeating a FPD-Link III interface forward and back channel?

0 Davor Glisic over 8 years ago in reply to AlexanderSt

TI__Expert 8165 points

Hi Alexander,

There is no device that can be inserted between an FPD-Link III serializer and deserializer.

Regards,

Davor

Interface

Interface forum

DS90UB913/914 with LVDS repeater