SBOS258 Data sheet

SBOS258E November 2002 – April 2025 OPA698

PRODUCTION DATA

8.2.7 Very High-Speed Schmitt Trigger

Figure 8-12 shows a very high-speed Schmitt trigger. The output levels are precisely defined, and the switching time is exceptional. The output voltage swings between V_H and V_L. The circuit operates as follows. When the input voltage is less than V_HL, then the output is limiting at V_H. When the input is greater than V_HH then the output is limiting at V_L, with V_HL and V_HH defined as:

Equation 12.

V_{H L, H H} = \frac{R_{1} | | R_{2} | | R_{3}}{R_{1}} \times V_{R E F} + \frac{R_{1} | | R_{2} | | R_{3}}{R_{2}} \times V_{O U T}

Due to the inverting function realized by the Schmitt trigger, V_HL corresponds to V_OUT = V_H, and V_HH corresponds to V_OUT = V_L. Figure 8-23 shows the Schmitt trigger operating with V_REF = 5V, and gives V_HH = 2.4V and V_HL = 1.6V. The OPA698 propagation delay in a Schmitt-trigger configuration is 6ns from high-to-low and 5ns from low-to-high.

Figure 8-22 Very High-Speed Schmitt Trigger

OPA698 Schmitt-Trigger
Time-Domain Response for a 10MHz Sine Wave

Figure 8-23 Schmitt-Trigger Time-Domain Response for a 10MHz Sine Wave