LMH0340: M23145G-14,M23428G-33

Rakesh Reddy Yara

Part Number: LMH0340

Tool/software:

Hi team,

In my ZYNQ MPSOC custom board, iam using the SDI serializer (LMH0340). I am attaching the serializer schematic for reference. The output of the serializer is connected to a MACOM equalizer (M23145G-14), and then the signal is sent to the cable driver (M23428G-33). I am not getting any output from the cable driver.

We also tried taking the output directly from the serializer but still did not get any output.

In both cases, I observe that the #lock signal at the serializer is low, which suggests a possible issue. I am not getting any output in either case.

11 months ago

0 Nick Peabody 11 months ago

TI__Genius 9209 points

Hi Rakesh,

The Lock_n signal being low suggests that the serializer is locked to the input signals.

From your schematic, I notice you're missing the inductor in the impedance matching network on your 75 ohm TXOUTs. Without a complete impedance matching network, you can't meet the required Output Return Loss SMPTE specification. However, you would still see some signal on TXOUT, so if there's no output the problem is somewhere else.

Do you have SMBus communication with the device and can you send me a register dump when the device is active?

Best,

Nick

0 Rakesh Reddy Yara 11 months ago in reply to Nick Peabody

Prodigy 30 points

For that path, everything seems fine, and even though we placed the inductor in parallel with R258, we are still not getting any output.

We have not used SMBUS configuration; we are just using hardware mode.

0 Nick Peabody 11 months ago in reply to Rakesh Reddy Yara

TI__Genius 9209 points

Hi Rakesh,

Have you been able to see an output from the MPSoC?

Best,

Nick

0 Rakesh Reddy Yara 11 months ago in reply to Nick Peabody

Prodigy 30 points

Iam new to video signal project.

How can I view the video signal from the MPSOC? We are currently checking the status signals, such as #lock.

The serializer output is fed to the MACOM reclocker (M23145G-14), followed by the MACOM driver(M23428G-33), as shown in the schematic.

Is the serializer output compatible with the MACOM reclocker and driver?

+1 Nick Peabody 11 months ago in reply to Rakesh Reddy Yara

TI__Genius 9209 points

Hi Rakesh,

Understandable. Yes, checking the #lock pin is a good way as well. When the #lock is low, the PLL of the LMH0340 is locked.

Rakesh Reddy Yara said:
Is the serializer output compatible with the MACOM reclocker and driver?

The LMH0340 outputs SDI data, so as long as the MACOM devices are SMPTE compliant then they should work.

Are you using https://www.ti.com/tool/BROADCAST_VIDEO_SERDES_IP?

^TI provides some sample FPGA code.

Best,

Nick

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LMH0340: M23145G-14,M23428G-33