AN4071

Hysteresis

Doc ID 022939 Rev 1

21/27

Figure 25.

Zoom of the signal (green OUT, blue IN+), time scale 20 ns/div.

Main general contributors leading to device oscillation

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Parasitic capacity/inductance onboard: long narrow wires, signal and output track close

together, device plugged into socket

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Fast (sharp) output edges: faster edge means higher dV/dT and therefore bigger

impact of parasitic capacities and inductances on the board

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High impedance on input pins: sensitivity to noise, increased effect of parasitic

structures and signal crosstalk

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Poor grounding

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High power supply impedance: inappropriate or missing bypass capacitor

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No hysteresis (static or dynamic) implemented

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Use of high-speed comparator where it isn't necessary.