The AC coupling capacitor of the TLK2711

user4592894

Dear all,

I have a design using TLK2711 described as follows：

1) Two PCB board communicate through TLK2711 at a rate of 2Gbps.

2) I use the connector of MicroQuad provided by AirBorn, with the cable of 2m.

As instructed in the datasheet, the AC coupling capcitor should be 1~10nF. For our design, is it better of worse if we choose a capacitor of 100nF？

over 8 years ago

0 Luis Omar Moran over 8 years ago

TI__Genius 16150 points

Hi,

The 1-10nF value is the recommended value for most applications, but depending on the data transition density and the receiver’s characteristics a different value could be appropriate. If the value is too small, the capacitor could become fully charged or depleted during longer strings of consecutive 1’s or 0’s respectively. This can cause bit errors because the data will not pass, and also because the common mode of the signals will change and causing the receiver to improperly sample the data. Likewise, if the capacitor value is too large, it could cause bit errors by preventing the AC data to pass at higher data rate due to a slower charge constant.

Best Regards,
Luis Omar Moran
High Speed Interface
SWAT Team

0 user4592894 over 8 years ago in reply to Luis Omar Moran

Prodigy 70 points

Hi,
Thanks for your warm-heart answer. Accturally, our design employ two 10nF capacitor at both transmitter(tlk2711) and receiver(tlk2711), and the error come out during the temperature experiments at -40℃, only a few byte error per hour. And we removed the 10nF capacitor at the transmitter, the error probability decreased largerd, and become a few byte error per 40 hours！

So we are looking for if its valid or theoretically possible to change the 10nF capacitor at the receiver(tlk2711) to 100nF？

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The AC coupling capacitor of the TLK2711