Part Number: TXB0108
We are using TXB0108 in one of our project.
When tested independently on oscilloscope and when loopbacked with same buffer other signals, the waveform transactions are ok.
But when card is connected in a System with other cards, where signal from TXB0108 are going out to other card then there is unwanted oscillations on the signal.
What could be the issue?
Pls check snapshots and Buffer circuit.
Need to check this closely as our many boards are using this buffer.
TXB Buffer pulldowns are not mounted at present.
In reply to Amit Jagtap:
In reply to Emrys Maier:
Yes I checked in datasheets it is 70pF capacitor maximum what it supports.
But now since the board is ready we need some work around to proceed further.
we have one pull down and one schottkey diode in path.
Kindly suggest some thing by which the required current can be boosted.
I have though off TXS series of ICs. As these ICs do not have internal series 4K resistor in path,
If I increase the current drive from FPGA to maximum then will it help to solve this issue.
Can you suggest proper Thevenin Termination so that it can provide the required current to drive the load capacitance.
I Calculated and tried R1 = 76E and R2 = 150E but waveform was not proper.
I tried with different series termination values and found that resistor around 300E gives better shape of the waveform.
Can you suggest proper Thevenin Termination to be used for this case.
Hi Emrys Maier,
I know TXB/TXS buffers are not meant for backplane driving. We are going to change it in 2nd spin of board with proper direction buffer with high current capability.
As this is a prototype board we want to show demo to our customers with present TXB/TXS buffer in the circuit.
And that's why looking for possible work around.
As this is Auto Bidirectional buffer, Can we add a very low cut-in voltage Schottky Diode in series with buffer output so that it will force to work in one direction.
Well I want to simulate all these scenarios but buffer spice model is not available.
Can you share TXB0108 and TXS0108 SPICE models.
For you reference I am adding a waveform snapshot without series termination and with series termination.
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