SN74ALS232B

16

× 4 ASYNCHRONOUS FIRST-IN, FIRST-OUT MEMORY

SCAS251B – FEBRUARY 1989 – REVISED APRIL 1998

7

POST OFFICE BOX 655303

PARAMETER MEASUREMENT INFORMATION

tPHZ

tPLZ

tPHL

tPLH

0.3 V

tPZL

tPZH

tPLH

tPHL

LOAD CIRCUIT FOR 3-STATE OUTPUTS

From Output

Under Test

Test Point

R1 = 500

Ω

S1

CL = 50 pF

7 V

(see Note A)

Open

1.3 V

1.3 V

1.3 V

3.5 V

3.5 V

0.3 V

0.3 V

th

tsu

VOLTAGE WAVEFORMS

SETUP AND HOLD TIMES

Timing

Input

Data

Input

1.3 V

1.3 V

3.5 V

3.5 V

0.3 V

0.3 V

High-Level

Pulse

Low-Level

Pulse

VOLTAGE WAVEFORMS

PULSE DURATION

Input

(see Note C)

Out-of-Phase

Output

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

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

SWITCH POSITION TABLE

R2 = 500

Ω

tw

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 ≤ 2 ns, tf ≤ 2 ns.

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

tPZH

tPZL

tPHZ

tPLZ

tPLH

tPHL

Open

Closed

Open

Closed

Open

Open

PARAMETER

S1

ten

tdis

tpd

Figure 1. Load Circuit and Voltage Waveforms