8.1.3 Application Curves

VOL – V

–20

0

20

40

60

80

100

–0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

TA = 25°C, VCC = 3 V,

VIH = 3 V, VIL = 0 V,

All Outputs Switching

Figure 8-2. Output Drive Current (IOL)

vs LOW-level Output Voltage (VOL)

–100

–80

–60

–40

–20

0

20

40

60

–1

–0.5 0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

TA = 25°C, VCC = 3 V,

VIH = 3 V, VIL = 0 V,

All Outputs Switching

VOH – V

Figure 8-3. Output Drive Current (IOH)

vs HIGH-level Output Voltage (VOH)

8.2 Power Supply Recommendations

The power supply can be any voltage between the MIN and MAX supply voltage rating located in the Section 5.3

table.

Each VCC pin should have a good bypass capacitor to prevent power disturbance. For devices with a single

supply, 0.1 μf is recommended; if there are multiple VCC pins, then 0.01 μf or 0.022 μf is recommended for each

power pin. It is acceptable to parallel multiple bypass caps to reject different frequencies of noise. A 0.1 μf and

a 1 μf are commonly used in parallel. The bypass capacitor should be installed as close to the power pin as

possible for best results.

8.3 Layout

8.3.1 Layout Guidelines

When using multiple bit logic devices, inputs should not float. In many cases, functions or parts of functions of

digital logic devices are unused. Some examples are when only two inputs of a triple-input AND gate are used,

or when only 3 of the 4-buffer gates are used. Such input pins should not be left unconnected because the

undefined voltages at the outside connections result in undefined operational states.

Specified in Figure 8-4 are rules that must be observed under all circumstances. All unused inputs of digital logic

devices must be connected to a high or low bias to prevent them from floating. The logic level that should be

applied to any particular unused input depends on the function of the device. Generally they will be tied to GND

or VCC, whichever makes more sense or is more convenient.

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SN74LVC125A

SCAS290R – JANUARY 2015 – REVISED FEBRUARY 2024

Copyright © 2024 Texas Instruments Incorporated

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