SN54ALS257A, SN54ALS258A, SN74ALS257A, SN74ALS258A, SN74AS257, SN74AS258

QUADRUPLE 2LINE TO 1LINE DATA SELECTORS/MULTIPLEXERS

WITH 3STATE OUTPUTS

SDAS124C − APRIL 1982 − REVISED AUGUST 1996

8

POST OFFICE BOX 655303

POST OFFICE BOX 1443

PARAMETER MEASUREMENT INFORMATION

SERIES 54ALS/74ALS AND 54AS/ 74AS DEVICES

tPHZ

tPLZ

tPHL

tPLH

0.3 V

tPZL

tPZH

tPLH

tPHL

LOAD CIRCUIT

FOR 3-STATE OUTPUTS

From Output

Under Test

Test

Point

R1

S1

CL

(see Note A)

7 V

1.3 V

1.3 V

3.5 V

3.5 V

0.3 V

0.3 V

High-Level

Pulse

Low-Level

Pulse

tw

VOLTAGE WAVEFORMS

PULSE DURATIONS

Input

Out-of-Phase

Output

(see Note C)

1.3 V

1.3 V

1.3 V

1.3 V

1.3 V

1.3 V

1.3 V

1.3 V

1.3 V

1.3 V

3.5 V

3.5 V

0.3 V

0.3 V

VOL

VOH

VOH

VOL

Output

Control

(low-level

enabling)

Waveform 1

S1 Closed

(see Note B)

Waveform 2

S1 Open

(see Note B)

[0 V

VOH

VOL

[3.5 V

In-Phase

Output

0.3 V

1.3 V

1.3 V

VOLTAGE WAVEFORMS

PROPAGATION DELAY TIMES

VOLTAGE WAVEFORMS

ENABLE AND DISABLE TIMES, 3-STATE OUTPUTS

R2

RL = R1 = R2

NOTES: A. CL includes probe and jig capacitance.

B. Waveform 1 is for an output with internal conditions such that the output is low except when disabled by the output control.

Waveform 2 is for an output with internal conditions such that the output is high except when disabled by the output control.

C. When measuring propagation delay items of 3-state outputs, switch S1 is open.

D. All input pulses have the following characteristics: PRR

≤ 1 MHz, tr = tf = 2 ns, duty cycle = 50%.

E. The outputs are measured one at a time with one transition per measurement.

Figure 1. Load Circuits and Voltage Waveforms