Table 7-1. Function Table (continued)

INPUTS

OUTPUTS

PRE

CLR

CLK

D

Q

Q

H

H

↑

L

L

H

H

H

L

X

Q0

Q 0

(1)

This configuration is nonstable; that is, it does not persist when

PRE or CLR returns to its inactive (high) level.

8 Application and Implementation

Note

Information in the following applications sections is not part of the TI component specification, and

TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining

suitability of components for their purposes. Customers should validate and test their design

implementation to confirm system functionality.

8.1 Application Information

A common application for the SN74LVC74A is a frequency divider. By connecting the Q output to the D input, the

Q output toggles states on each positive edge of the incoming clock signal. Because it takes two positive edges,

or two clock pulses, to complete one complete pulse on the output (one pulse to toggle from low to high, another

to toggle from high to low), the incoming clock frequency is effectively divided by two.

8.2 Typical Application

SN74LVC74A

Clock Input

VCC

1CLK

Q

GND

Q

1D

3 V

Output

Copyright © 2016, Texas Instruments Incorporated

Figure 8-1. Frequency Divider

8.2.1 Design Requirements

This device uses CMOS technology and has balanced output drive. Avoid bus contention because it can drive

currents in excess of maximum limits. The high drive also creates fast edges into light loads, so consider routing

and load conditions to prevent ringing.

8.2.2 Detailed Design Procedure

1. Recommended input conditions:

• For rise time and fall time specification, see (Δt/ΔV) in Recommended Operating Conditions.

• For specified high and low levels, see (VIH and VIL) in Recommended Operating Conditions.

• Inputs are overvoltage tolerant allowing them to go as high as (VI max) in Recommended Operating

Conditions at any valid VCC.

2. Recommended maximum output conditions:

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SN54LVC74A, SN74LVC74A

SCAS287W – JANUARY 1993 – REVISED DECEMBER 2024

Copyright © 2024 Texas Instruments Incorporated

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