TLK1221: how to reduce TLK1221 BER

Sean ZHang35753

Intellectual 2060 points

Part Number: TLK1221
Other Parts Discussed in Thread: TEST2

Hi,

My customer used TLK1221 on industrial inkjet printer projects. There is not BER issue with 3 meters cable, but BER happended with 5 meters cable.

Attachment is the schematic, R340 and R341 was not soldered. Customer debugged through below modification to get some improvement, but can not avoid BER. Could you please provide a guide how to avoid BER issue?

1, test 1: changed 3C11，3C12，3C13，3C14 to 0.1uF, get a bittle improvement.

2, test2: changed 3C11，3C12，3C13，3C14 to 0.1uF and removed R346，R347, get more improvement.

over 4 years ago

0 Rodrigo Natal over 4 years ago

TI__Mastermind 19225 points

Hi,

What does the input signal to the TLK receiver look like? is the minimum input eye opening per datasheet of 0.25UI being met?

Have you tried increasing the Tx amplitude for the signal being launched into the 5m cable?

Regards,

Rodrigo Natal

HSSC Applications Engineer

0 Sean ZHang35753 over 4 years ago in reply to Rodrigo Natal

TI__Intellectual 2060 points

Hi,

I did not find any guide how to increase Tx amplitude from TLK1221 datasheet on TI web.

Could you please provide more guide? thanks.

Regards

Seanzhang

0 Rodrigo Natal over 4 years ago in reply to Sean ZHang35753

TI__Mastermind 19225 points

Hi,

My mistake, the output amplitude is fixed with typical value of around 850mVppd.

For the AC coupling caps I'd suggest the value of 0.1uF that you are using.

I believe your application circuit should look like Figure 12 in the TLK1221 datasheet. Specifically, other than the AC coupling caps on TX outputs and Rx inputs and the 50 Ohm single ended terminations plus common-mode capacitor there should not be any other external components needed on the TLK high-speed inputs and outputs. You should be able to get rid of R340 - R349.

Cordially,

Rodrigo Natal

HSSC Applications Engineer

0 Sean ZHang35753 over 4 years ago in reply to Rodrigo Natal

TI__Intellectual 2060 points

Hi,

thanks your help, this issue has been resolved through using better materials cables.

Best Regards

Sean zhang

Interface

Interface forum

TLK1221: how to reduce TLK1221 BER