SN74LVC541APWR datasheet(13/46 Pages) TI2

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8.2.1.2 Input Considerations

Input signals must cross VIL(max) to be considered a logic LOW, and VIH(min) to be considered a logic HIGH. Do

not exceed the maximum input voltage range found in the Absolute Maximum Ratings.

Unused inputs must be terminated to either VCC or ground. The unused inputs can be directly terminated if the

input is completely unused, or the inputs can be connected with a pullup or pulldown resistor if the input is

used sometimes, but not always. A pullup resistor is used for a default state of HIGH, and a pulldown resistor is

used for a default state of LOW. The drive current of the controller, leakage current into the SNx4LVC541A (as

specified in the Electrical Characteristics), and the desired input transition rate limits the resistor size. A 10kΩ

resistor value is often used due to these factors.

The SNx4LVC541A has CMOS inputs and thus requires fast input transitions to operate correctly, as defined in

the Electrical Characteristics table. Slow input transitions can cause oscillations, additional power consumption,

and reduction in device reliability.

Refer to the Feature Description for additional information regarding the inputs for this device.

8.2.1.3 Output Considerations

The positive supply voltage is used to produce the output HIGH voltage. Drawing current from the output

decreases the output voltage as specified by the VOH specification in the Electrical Characteristics. The ground

voltage is used to produce the output LOW voltage. Sinking current into the output increases the output voltage

as specified by the VOL specification in the Electrical Characteristics.

Push-pull outputs that can be in opposite states, even for a very short time period, must never be connected

directly together. This can cause excessive current and damage to the device.

Two channels within the same device with the same input signals can be connected in parallel for additional

output drive strength.

Unused outputs can be left floating. Do not connect outputs directly to VCC or ground.

Refer to the Feature Description section for additional information regarding the outputs for this device.

8.2.2 Detailed Design Procedure

1. Add a decoupling capacitor from VCC to GND. The capacitor needs to be placed physically close to the

device and electrically close to both the VCC and GND pins. An example layout is shown in the Layout

section.

2. Verify that the capacitive load at the output is ≤ 50pF. Low load capacitance can be accomplished by

providing short, appropriately sized traces from the SNx4LVC541A to the receiving device.

3. Verify that the resistive load at the output is larger than (VCC / IO(max))Ω. Never violate the maximum output

current from the Absolute Maximum Ratings. Most CMOS inputs have a resistive load measured in MΩ;

much larger than the minimum calculated previously.

4. Thermal issues are rarely a concern for logic gates; however, the power consumption and thermal increase

can be calculated using the steps provided in the CMOS Power Consumption and Cpd Calculation

application note.

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SN54LVC541A, SN74LVC541A

SCAS298O – JANUARY 1993 – REVISED JUNE 2026

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SN74LVC541APWR Datasheet(PDF) 13 Page - Texas Instruments