74LVC257APWDH 查看數據表（PDF） - Philips Electronics

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74LVC257APWDH

Quad 2-input multiplexer with 5 Volt tolerant inputs/outputs (3-State)

Philips Electronics 

Philips Semiconductors

Quad 2-input multiplexer with 5 Volt tolerant

inputs/outputs (3-State)

Product specification

74LVC257A

AC WAVEFORMS

VM = 0.5 × VCC at VCC < 2.7 V

VM = 1.5 V at VCC ≥ 2.7 V

VX = VOL + 0.3 V at VCC ≥ 2.7 V

VX = VOL + 0.1 × VCC at VCC < 2.7 V

VY = VOH – 0.3 V at VCC ≥ 2.7V

VY = VOH – 0.1 × VCC at VCC < 2.7 V

VOL and VOH are the typical output voltage drop that occur with the

output load.

VCC

S, nI0, nI1

VM

INPUTS

GND

VOH

tPHL

tPLH

nY OUTPUT

VM

VOL

SV00641

Figure 1. Input (S, nl0, nl1) to output (nY) propagation delays.

VI

OE INPUT

GND

VCC

OUTPUT

LOW-to-OFF

OFF-to-LOW

VOL

VOH

OUTPUT

HIGH-to-OFF

OFF-to-HIGH

GND

VM

tPLZ

tPZL

VX

tPHZ

VY

outputs

enabled

VM

tPZH

outputs

disabled

VM

outputs

enabled

SV00642

Figure 2. 3-state enable and disable times.

TEST CIRCUIT

VI

PULSE

GENERATOR

VCC

D.U.T.

RT

VO

CL 50pF

S1

500Ω

2 x VCC

Open

GND

500Ω

VCC

t 2.7V

2.7V – 3.6V

VI

VCC

2.7V

Test

tPLH/tPHL

tPLZ/tPZL

tPHZ/tPZH

S1

Open

2 x VCC

GND

SY00003

Figure 3. Load circuitry for switching times.

1998 Jul 29

6

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