Other Parts Discussed in Thread: SN74AHC244
Hi TI team
Please refer attached Function Block Diagram, we used two TI logic IC, one is octal buffer and one is shifter logic IC.
Currently the U349 pin2 of input clock waveform whithout the overshoot on rising edge, but the U349 output clock waveform all whith the overshoot on rising edge.
We trird to adjust the series resistors(R5321 to R5328) to 33 ohm, it looks the overshoot are not changed obviously, we need to adjust the series resistors(R5321 to R5328) to 127 ohm, the overshoot will be changed obviously, please refer attached waveform.
My question are:
1. Why the U349(octal buffer) input clock waveform without the overshoot on rising edge, but he U349 output clock waveform all with the overshoot on rising edge?
2. It looks the series resistors(R5321 to R5328) change to 127 ohm, the overshoot will be changed obviously, how can we make sure the series resistors(R5321 to R5328) value is reasonable?
3. The U349 buffer output is connected to U352(TI shifter logic IC SN74LV164APWR), the shifter logic IC VIH/VIL all meet the SPEC, but the clock waveform with the overshoot on rising edge, is it acceptable?
Thanks
Jerry