9 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, as well as validating and testing their design

implementation to confirm system functionality.

9.1 Application Information

In this application, three 2-input OR gates are combined to produce a 4-input OR gate function as shown in

Figure 9-1. The fourth gate can be used for another application in the system, or the inputs can be grounded and

the channel left unused.

This device is used to directly control the Enable pin of a fan driver. The fan driver requires only one input signal

to be HIGH before being enabled, and should be disabled in the event that all signals go LOW. The 4-input OR

gate function combines the four individual overheat signals into a single active-high enable signal.

9.2 Typical Application

EN

Device 1

Overhe at

Fan

Driver

Device 2

Overhe at

Device 3

Overhe at

Device 4

Overhe at

Figure 9-1. Typical application schematic

9.2.1 Design Requirements

9.2.1.1 Power Considerations

Ensure the desired supply voltage is within the range specified in the Recommended Operating Conditions. The

supply voltage sets the device's electrical characteristics as described in the Electrical Characteristics.

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

CD74HC32 plus the maximum supply current, ICC, listed in the Electrical Characteristics. The logic device can

only source or sink as much current as it is provided at the supply and ground pins, respectively. Be sure not to

exceed the maximum total current through GND or VCC listed in the Absolute Maximum Ratings.

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

Cpd Calculation.

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

and Logic (SLL) Packages and Devices.

CD74HC32, CD54HC32

SCHS274D – SEPTEMBER 1997 – REVISED APRIL 2021

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