74HC257 查看數據表（PDF） - NXP Semiconductors.

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74HC257

Quad 2-input multiplexer; 3-state

NXP Semiconductors. 

NXP Semiconductors

74HC257; 74HCT257

Quad 2-input multiplexer; 3-state

VI 90 %

tW

negative

pulse

VM

10 %

0V

tf

VI

positive

pulse

tr

90 %

VM

10 %

0V

tW

VM

tr

tf

VM

VI

G

VCC

VO

DUT

RT

VCC

RL S1

CL

open

001aad983

Fig 8.

Measurement points are given in Table 8 and test data is given in Table 9.

Definitions test circuit:

RT = Termination resistance should be equal to output impedance Zo of the pulse generator.

CL = Load capacitance including jig and probe capacitance.

RL = Load resistor.

Test circuit for switching times

Table 9. Test data

Type

Input

VI

tr, tf

74HC257

VCC

6 ns

74HCT257 3 V

6 ns

Load

CL

50 pF

50 pF

RL

1 kΩ

1 kΩ

Switch position

tPHL, tPLH

open

tPZH, tPHZ

GND

open

GND

tPZL, tPLZ

VCC

VCC

74HC_HCT257_5

Product data sheet

Rev. 05 — 13 January 2010

© NXP B.V. 2010. All rights reserved.

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