6 Parameter Measurement Information

Phase relationships between waveforms were chosen arbitrarily for the examples listed in the following table. All

input pulses are supplied by generators having the following characteristics: PRR ≤ 1MHz, ZO = 50Ω, tt ≤ 2.5ns.

The outputs are measured individually with one input transition per measurement.

VCC

Vt

RL

CL

ΔV

1.8V ± 0.15V

VCC/2

1kΩ

30pF

0.15V

2.5V ± 0.2V

VCC/2

500Ω

30pF

0.15V

2.7V

1.5V

500Ω

50pF

0.3V

3.3V ± 0.3V

1.5V

500Ω

50pF

0.3V

CL

(1)

From Output

Under Test

Test

Point

RL

(1) CL includes probe and test-fixture capacitance.

Figure 6-1. Load Circuit for Push-Pull Outputs

Vt

Input

Vt

VCC

0 V

50%

50%

VOH

VOL

tPLH

(1)

tPHL

(1)

VOH

VOL

tPHL

(1)

tPLH

(1)

Output

Waveform 1

Output

Waveform 2

50%

50%

(1) The greater between tPLH and tPHL is the same as tpd.

Figure 6-2. Voltage Waveforms Propagation Delays

VOH

VOL

Output

VCC

0 V

Input

tf

(1)

tr

(1)

90%

10%

90%

10%

tr

(1)

90%

10%

tf

(1)

90%

10%

(1) The greater between tr and tf is the same as tt.

Figure 6-3. Voltage Waveforms, Input and Output Transition Times

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SN54LVC74A, SN74LVC74A

SCAS287W – JANUARY 1993 – REVISED DECEMBER 2024

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