LTC489C 查看數據表（PDF） - Linear Technology

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LTC489C

Quad RS485 Line Receiver

Linear Technology 

LTC488/LTC489

TEST CIRCUITS

100pF

A

D

DRIVER

54Ω

100pF

RECEIVER

B

RO

CL

4889 F01

Figure 1. Receiver Timing Test Circuit

Note: The input pulse is supplied by a generator having the following characteristics:

f = 1MHz, Duty Cycle = 50%, tr < 10ns, tf ≤ 10ns, ZOUT = 50Ω

RECEIVER

OUTPUT

S1

1k

VCC

CL

1k

S2

4889 F02

Figure 2. Receiver Enable and Disable Timing Test Circuit

SWITCHING TIME WAVEFORMS

VOD2

INPUT

A, B

–VOD2

VOH

RO

VOL

INPUT

f = 1MHz; tr ≤ 10ns; tf ≤ 10ns

0V

tPHL

0V

tPLH

1.5V

1.5V

4889 F03

Figure 3. Receiver Propagation Delays

3V

EN OR

EN12

0V

5V

RO

VOL

VOH

RO

0V

f = 1MHz; tr ≤ 10ns; tf ≤ 10ns

1.5V

1.5V

tZL

tLZ

1.5V OUTPUT NORMALLY LOW

tZH

tHZ

OUTPUT NORMALLY HIGH

1.5V

Figure 4. Receiver Enable and Disable Times

0.5V

0.5V

4889 F04

6

4889fb

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