PG

ON/OFF

RESET

Power Supply

Motor Controller

On/Off Switch

Over

Current

Detection

OC

9

SN74HCS11-Q1

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SCLS760A – AUGUST 2019 – REVISED OCTOBER 2019

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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. Customers should

validate and test their design implementation to confirm system functionality.

9.1 Application Information

The SN74HCS11-Q1 includes three 3-input AND gates with Schmitt-trigger inputs. These 3-input AND gates

work independently, but can be combined to get up to a 7-input AND gate. It can be used with all three inputs

active, or one input can be disabled by directly connecting them to VCC to turn the device into a 2-input AND

gate.

The SN74HCS11-Q1 is used to control the RESET pin of a motor controller. This system requires three input

signals to all be HIGH before the controller is enabled, and should be disabled in the event that any one signal

goes LOW. The 3-input AND gate combines the 3 individual reset signals into a single active-low reset signal.

Many power good signals utilize open-drain outputs which can produce slow input transition rates when they

transition from LOW to Hi-Z mode. This makes the SN74HCS11-Q1 ideal for the application because it has

Schmitt-trigger inputs that do not have input transition rate requirements.

9.2 Typical Application

Figure 9. Typical application block diagram

9.2.1 Design Requirements

•

All signals in the system operate at 5 V

•

The motor controller should be disabled if any of these conditions apply:

–

Power Supply is not ready (PG)

–

Excessive current is detected (OC)

–

The power switch is in the OFF position (ON/OFF)

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

SN74HCS11-Q1 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.