SN54AHCT257, SN74AHCT257

QUADRUPLE 2-LINE TO 1-LINE DATA SELECTORS/MULTIPLEXERS

WITH 3-STATE OUTPUTS

SCLS351E – MAY 1996 – REVISED OCTOBER 1998

6

POST OFFICE BOX 655303

PARAMETER MEASUREMENT INFORMATION

50% VCC

3 V

3 V

0 V

0 V

th

tsu

VOLTAGE WAVEFORMS

SETUP AND HOLD TIMES

Data Input

tPLH

tPHL

tPHL

tPLH

VOH

VOH

VOL

VOL

3 V

0 V

50% VCC

50% VCC

Input

Out-of-Phase

Output

In-Phase

Output

Timing Input

50% VCC

VOLTAGE WAVEFORMS

PROPAGATION DELAY TIMES

INVERTING AND NONINVERTING OUTPUTS

Output

Control

Output

Waveform 1

S1 at VCC

(see Note B)

Output

Waveform 2

S1 at GND

(see Note B)

VOL

VOH

tPZL

tPZH

tPLZ

tPHZ

≈ VCC

0 V

50% VCC

VOL + 0.3 V

50% VCC

≈ 0 V

3 V

VOLTAGE WAVEFORMS

ENABLE AND DISABLE TIMES

LOW- AND HIGH-LEVEL ENABLING

tPLH/tPHL

tPLZ/tPZL

tPHZ/tPZH

Open Drain

Open

VCC

GND

VCC

TEST

S1

3 V

0 V

1.5 V

tw

VOLTAGE WAVEFORMS

PULSE DURATION

Input

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. All input pulses are supplied by generators having the following characteristics: PRR

≤ 1 MHz, ZO = 50 Ω, tr ≤ 3 ns, tf ≤ 3 ns.

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

From Output

Under Test

CL

(see Note A)

LOAD CIRCUIT FOR

3-STATE AND OPEN-DRAIN OUTPUTS

S1

VCC

RL = 1 kΩ

GND

From Output

Under Test

CL

(see Note A)

Test

Point

LOAD CIRCUIT FOR

TOTEM-POLE OUTPUTS

Open

VOH – 0.3 V

1.5 V

1.5 V

1.5 V

1.5 V

1.5 V

1.5 V

1.5 V

1.5 V

Figure 1. Load Circuit and Voltage Waveforms