CD74AC238

3-LINE TO 8-LINE DECODER/DEMULTIPLEXER

SCHS331 – FEBRUARY 2003

6

POST OFFICE BOX 655303

PARAMETER MEASUREMENT INFORMATION

VOLTAGE WAVEFORMS

SETUP AND HOLD AND INPUT RISE AND FALL TIMES

th

tsu

50% VCC

50% VCC

50%

10%

10%

90%

90%

VCC

VCC

0 V

0 V

tr

tf

Reference

Input

Data

Input

VOLTAGE WAVEFORMS

PROPAGATION DELAY AND OUTPUT TRANSITION TIMES

50% VCC

50% VCC

50%

10%

10%

90%

90%

VCC

VOH

VOL

0 V

tr

tf

Input

In-Phase

Output

50% VCC

tPLH

tPHL

50% VCC

50%

10%

10%

90%

90%

VOH

VOL

tr

tf

tPHL

tPLH

Out-of-Phase

Output

NOTES: A. CL includes probe and test-fixture 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.

Phase relationships between waveforms are arbitrary.

D. For clock inputs, fmax is measured with the input duty cycle at 50%.

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

F. tPLH and tPHL are the same as tpd.

G. tPZL and tPZH are the same as ten.

H. tPLZ and tPHZ are the same as tdis.

I. All parameters and waveforms are not applicable to all devices.

From Output

Under Test

CL = 50 pF

(see Note A)

LOAD CIRCUIT

S1

2

× VCC

R1 = 500

Ω†

Open

GND

0 V

tw

VOLTAGE WAVEFORMS

PULSE DURATION

Input

50% VCC

50% VCC

VCC

tPLH/tPHL

tPLZ/tPZL

tPHZ/tPZH

Open

2

× VCC

GND

TEST

S1

Output

Control

Output

Waveform 1

S1 at 2

× VCC

(see Note B)

Output

Waveform 2

S1 at GND

(see Note B)

VOL

VOH

tPZL

tPZH

tPLZ

tPHZ

≈VCC

0 V

50% VCC

20% VCC

50% VCC

≈0 V

VOLTAGE WAVEFORMS

OUTPUT ENABLE AND DISABLE TIMES

50% VCC

50% VCC

80% VCC

VCC

R2 = 500

Ω†

† When VCC = 1.5 V, R1 = R2 = 1 kΩ

VOLTAGE WAVEFORMS

RECOVERY TIME

50% VCC

VCC

0 V

CLR

Input

CLK

50% VCC

VCC

trec

0 V

Figure 1. Load Circuit and Voltage Waveforms