The TXS and TXB level shifter families as shown
in Voltage Translators and Level
Shifters are designed with one-shots
for a set duration of pulse width for optimal
signal integrity, impacted by RC components.
Therefore, intentional and careful considerations
should be made when used with additional external
components as majority of one-shot concerns are
due to improper use of the devices, false
triggering of the one-shots and poor layout
design.
- Consider short enough traces for round-trip delay
reflections within the one-shot duration of 10-30
ns.
- Consider any tolerances of any additional RC
components, similar to the data sheet
recommendations. Consider using fast enough input
edges per the input transition rate while avoiding
floating inputs as stated in the data sheets.
- Unless otherwise noted in the data sheets, makes
sure <70 pF lumped capacitance designed for
performance per the data sheet’s recommended data
rates.
- Avoid timing-out the one-shot duration with
additional parasitic capacitance as trace length
and connectors yields additional capacitive
loading.
- One-shot triggers when they detect rising or
falling edges. Reflections and or ringing can
cause false triggers. Ringing is also caused by
capacitance and inductance of long cables and or
traces and can also be amplified by unstable GND
or VCC voltages.
- Consider the impact on temperature per the output
impedance, as mismatched impedance with PCB traces
yield reflections that can be amplified by the
one-shot as false edge triggers.