7 Detailed Description

7.1 Overview

These 'ACT14 devices perform the Boolean function Y = A. Because of the Schmitt action, they have different

input threshold levels for positive-going (VT+) and for negative-going (VT−) signals.

These circuits are temperature compensated and can be triggered from the slowest of input ramps and still give

clean, jitter-free output signals. They also have a greater noise margin than conventional inverters.

7.2 Functional Block Diagram

7.3 Feature Description

• VCC is optimized at 5 V

• Allows up voltage translation from 3.3 V to 5 V

– Inputs accept VIH levels of 2 V

• Slow edge rates minimize output ringing

• Inputs are TTL-Voltage compatible

7.3.1 Balanced CMOS Push-Pull Outputs

This device includes balanced CMOS push-pull outputs. The term balanced indicates that the device can sink

and source similar currents. The drive capability of this device may create fast edges into light loads, so routing

and load conditions should be considered to prevent ringing. Additionally, the outputs of this device are capable

of driving larger currents than the device can sustain without being damaged. It is important to limit the output

power of the device to avoid damage due to overcurrent. The electrical and thermal limits defined in the Absolute

Maximum Ratings must be followed at all times.

Unused push-pull CMOS outputs must be left disconnected.

7.3.2 Clamp Diode Structure

As shown in Figure 7-1, the inputs and outputs to this device have both positive and negative clamping diodes.

CAUTION

Voltages beyond the values specified in the Absolute Maximum Ratings table can cause damage

to the device. The input and output voltage ratings may be exceeded if the input and output clamp-

current ratings are observed.

GND

Logic

Input

Output

VCC

Device

-IIK

+IIK

+IOK

-IOK

Figure 7-1. Electrical Placement of Clamping Diodes for Each Input and Output

SN54ACT14, SN74ACT14

SCAS557K – DECEMBER 1995 – REVISED NOVEMBER 2024

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