Logic-Level Compatibility Checker

Compare a driving pin's guaranteed HIGH and LOW levels with a receiving pin's thresholds and input-voltage limits.

Method, formulas and references

Method

HIGH noise margin = V_OH(min) − V_IH(min). LOW noise margin = V_IL(max) − V_OL(max). Non-negative margins meet the static input thresholds; zero margin leaves no allowance for additional noise at that corner.

The driver's highest possible HIGH is also checked against the receiver's recommended operating input limit and absolute maximum input rating when entered. Passing an absolute maximum check does not imply reliable operation beyond the recommended limit. A receiver that can be unpowered while the driver remains active needs a separate datasheet check for I_off, input clamps and injection current.

This is a DC, single-ended logic check. It does not model propagation delay, edge rate, transmission-line effects, bus contention or the output-voltage change with loading. Use guaranteed datasheet corners for the specific pins and supply range.

Reference

Texas Instruments SCEA021A, Voltage-Level-Translation Devices, driver/receiver VIH, VIL, VOH and VOL compatibility.

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