74AC257 查看數據表（PDF） - STMicroelectronics

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74AC257

QUAD 2 CHANNEL MULTIPLEXER (3-STATE)

STMicroelectronics 

74AC257

AC ELECTRICAL CHARACTERISTICS (CL = 50 pF, RL = 500 Ω, Input tr = tf =3 ns)

Symbol

P ar ame te r

tPLH Propagation Delay Time

tPHL A,B to Y

tPLH Propagation Delay Time

tPHL SEL to Y

tPZL Output Enable Time

tPZH

tPLZ Output Disable Time

tPHZ

(*) Voltage range is 3.3V ± 0.3V

(**) Voltage range is 5V ± 0.5V

Test Condition

V CC

(V)

3.3(*)

5.0(**)

3.3(*)

5.0(**)

3.3(*)

5.0(**)

3.3(*)

5.0(**)

Value

TA = 25 oC

-40 to 85 oC

Min. Typ. Max. Min. Max.

1.5 5.5 8.5 1.5 9

1.5 4.5 6 1.5 7

1.5 7 10.5 1.5 11.5

1.5 5.5 7.5 1.5 8.5

1.5 5.5 9 1.5 10

1.5 4.5 7.5 1.5 8.5

1.5

7

10 1.5 11

1.5 5.5 9 1.5 10

Unit

ns

ns

ns

ns

CAPACITIVE CHARACTERISTICS

Symbol

P ar ame te r

Test Conditions

V CC

(V)

Value

TA = 25 oC

-40 to 85 oC

Min. Typ. Max. Min. Max.

Unit

COUT Output Capacitance

5.0

8

pF

CIN Input Capacitance

5.0

4

pF

CPD Power Dissipation

5.0

Capacitance (note 1)

20

pF

1) CPD is defined as the value of the IC’s internal equivalent capacitance which is calculated from the operating current consumption without load. (Refer to

Test Circuit). Average operating current can be obtained by the following equation. ICC(opr) = CPD • VCC • fIN + ICC/n (per circuit)

TEST CIRCUIT

T E ST

tPLH, tPHL

tPZL, tPLZ

tPZH, tPHZ

CL = 50 pF or equivalent (includes jig and probe capacitance)

RL = R1 = 500Ω or equivalent

RT = ZOUT of pulse generator (typically 50Ω)

SWITCH

Open

2VCC

Open

5/10

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