This thread has been locked.
If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.
Hi team,
my customer use the TXS0104 to translate the voltage of SMBUS. below is the schematic:
And they find in the -40°C, there will show the spur in CLK occasionally.
1:SMBUS DATA
2:SMBUS CLK
3:3.3V supply
It seems when the spur show, there is also a vibration in 3.3V supply.
So can you give your comment if the vibration in 3.3V can cause this?
Or what may be the root cause?
Lacey
Thanks a lot!
Lacey,
When you mention that the issue is seen at -40c, does that mean that other temp operations don't have this issue or if the application is only being run at -40C?
is the Vcc ringing seen at other temperatures as well or only pronounced at -40C? I do notice from the schematic that there are no bypass caps on the Vcc supplies, correct me if there is.
Also, there are strong pull-up resistors on the IO ports which are not advised, please read the app note about external pullup on TXS devices.
There are internal pull-up resistors in the TXS devices which is there to avoid having external resistors. There is also significant cap loading on the lines which are not advised either but it actually helps in suppressing the glitches seen. how long is the trace? The layout section suggests having short traces to avoid the reflection to create false triggering through the one-shot circuitry.
I would advise having bypass caps close to the device supply pins and remove external pull-up resistors and the additional cap on the lines.
Let me know if this helps.
Hi Shreyas,
Thanks very much for your reply!
you recommend to remove the 4.7K pull up resistor and 100pF cap in the output and also the resistor and cap in the input. is if correct?
I will also double check situation of the supply vibration and supply cap with customer. and will update the information.
From the information customer gave before, the issue only exist in low temperature.
Do you think what may be the root cause? The supply or the pull up resistor?
Lacey
Thanks a lot!