54ACT16821, 74ACT16821

20BIT BUSINTERFACE FLIPFLOPS

WITH 3STATE OUTPUTS

SCAS176A − JANUARY 1991 − REVISED APRIL 1996

6

POST OFFICE BOX 655303

POST OFFICE BOX 1443

PARAMETER MEASUREMENT INFORMATION

50% VCC

1.5 V

1.5 V

1.5 V

3 V

3 V

0 V

0 V

th

tsu

VOLTAGE WAVEFORMS

Data Input

tPLH

tPHL

tPHL

tPLH

VOH

VOH

VOL

VOL

1.5 V

1.5 V

3 V

0 V

50% VCC

50% VCC

Input

Out-of-Phase

Output

In-Phase

Output

Timing Input

50% VCC

VOLTAGE WAVEFORMS

From Output

Under Test

CL = 50 pF

(see Note A)

LOAD CIRCUIT

S1

2

× VCC

500

Ω

500

Ω

Output

Control

(low-level

enabling)

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

1.5 V

1.5 V

[ VCC

0 V

50% VCC

20% VCC

50% VCC

80% VCC

[ 0 V

3 V

GND

Open

VOLTAGE WAVEFORMS

tPLH/tPHL

tPLZ/tPZL

tPHZ/tPZH

Open

2

× VCC

GND

TEST

S1

3 V

0 V

1.5 V

1.5 V

tw

VOLTAGE WAVEFORMS

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.

Figure 1. Load Circuit and Voltage Waveforms