8.2.1 Design Requirements

8.2.1.1 Power Considerations

Ensure that the desired supply voltage is within the range specified in the Electrical Characteristics. The supply

voltage sets the device electrical characteristics of the device, as described in the Electrical Characteristics

section.

The positive voltage supply must be capable of sourcing current equal to the total current to be sourced by all

outputs of the SN74LVC595A plus the maximum static supply current, ICC, listed in the Electrical Characteristics,

and any transient current required for switching. The logic device can only source as much current that is

provided by the positive supply source. Ensure the maximum total current through VCC listed in the Absolute

Maximum Ratings is not exceeded.

The ground must be capable of sinking current equal to the total current to be sunk by all outputs of the

SN74LVC595A plus the maximum supply current, ICC, listed in the Electrical Characteristics, and any transient

current required for switching. The logic device can only sink as much current that can be sunk into its ground

connection. Ensure the maximum total current through GND listed in the Absolute Maximum Ratings is not

exceeded.

The SN74LVC595A can drive a load with a total capacitance less than or equal to 50pF while still meeting all of

the data sheet specifications. Larger capacitive loads can be applied; however, it is not recommended to exceed

50pF.

The SN74LVC595A can drive a load with total resistance described by RL ≥ VO / IO, with the output voltage and

current defined in the Electrical Characteristics table with VOH and VOL. When outputting in the HIGH state, the

output voltage in the equation is defined as the difference between the measured output voltage and the supply

voltage at the VCC pin.

Total power consumption can be calculated using the information provided in the CMOS Power Consumption

and Cpd Calculation application note.

Thermal increase can be calculated using the information provided in the Thermal Characteristics of Standard

Linear and Logic (SLL) Packages and Devices application note.

CAUTION

The maximum junction temperature, TJ(max) listed in the Absolute Maximum Ratings, is an additional

limitation to prevent damage to the device. Do not violate any values listed in the Absolute Maximum

Ratings. These limits are provided to prevent damage to the device.

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 they can be connected with a pull-up or pull-down resistor if the input will be used

sometimes, but not always. A pull-up resistor is used for a default state of HIGH, and a pull-down resistor is

used for a default state of LOW. The drive current of the controller, leakage current into the SN74LVC595A (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 SN74LVC595A 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.

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SN74LVC595A

SCASE93A – MAY 2025 – REVISED OCTOBER 2025

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