MAX3160(2000) 데이터 시트보기 (PDF) - Maxim Integrated

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MAX3160
(Rev.:2000)

+3.0V to +5.5V, 1µA, RS-232/RS-485/422 Multiprotocol Transceivers

Maxim Integrated 

+3.0V to+5.5V, 1µA, RS-232/RS-485/422

Multiprotocol Transceivers

Table 11. MAX3161

RS-485/RS-232

1

1

1

1

1

1

1

0

SHDN

0

1

1

1

1

1

1

X

INPUTS

HDPLX

X

0

0

0

1

1

1

X

A-B

X

≥-50mV

≤-200mV

Floating

X

X

X

X

Truth Tables (continued)

Y(A) - Z(B)

X

X

X

X

≥-50mV

≤-200mV

Floating

X

OUTPUT

RO/R2OUT

High-Z up to VCC

1

0

1

1

0

1

RS-232 mode

Table 12. MAX3162

SHDN

0

INPUTS

RE485

X

X

1

1

0

1

0

1

0

A-B

X

X

≥-50mV

≤-200mV

Inputs open

OUTPUT

RO

High-Z

High-Z

1

0

1

Table 13. Required Minimum Capacitance

Values

SUPPLY

VOLTAGE (V)

C1 (µF)

C2, C3, C4,

CBYPASS (µF)

+3.0 to +3.6

0.1

0.1

+4.5 to +5.5

0.047

0.33

+3.0 to +5.5

0.1

0.47

receiver input impedance (48kΩ), allowing up to 128

transceivers to be connected in parallel on one com-

munication line. The MAX3161/MAX3162 have a 1/8-

unit load receiver input impedance (96kΩ), allowing up

to 256 transceivers to be connected in parallel on one

communication line. Any combination of these devices

and/or other RS-485 transceivers with a total of 32-unit

loads or fewer can be connected to the line.

The MAX3160/MAX3161/MAX3162 RS-485 driver out-

puts are 1/8-unit load when disabled. This impedance

may be reduced if the D1 pin is toggled at a high fre-

quency. With no power applied (VCC = GND), the RS-

485 transmitter output impedances typically go to 1/2-

unit load on the MAX3161/MAX3162, and to one-unit

load on the MAX3160.

Driver Output Protection

Two mechanisms prevent excessive output current and

power dissipation caused by faults or by bus con-

tention. The first, a foldback current limit on the output

stage, provides immediate protection against short cir-

cuits over the whole common-mode voltage range (see

Typical Operating Characteristics). The second, a ther-

mal shutdown circuit, forces the driver outputs into a

high-impedance state if the die temperature becomes

excessive.

Protection Against Wiring Faults

EIA/TIA-485 standards require a common input voltage

range of -7V to +12V to prevent damage to the device.

The MAX3160/MAX3161/MAX3162 inputs are protected

to RS-232 levels of ±25V for the receiver inputs and

±13.2V for the transmitter/driver outputs. This provides

additional protection for the RS-485 transceivers

against ground differential or faults due to miswiring.

RS-485/422 Reduced EMI and Reflections

The MAX3160/MAX3161/MAX3162 can be configured

for slew-rate limiting by pulling FAST low. This minimizes

EMI and reduces reflections caused by improperly ter-

minated cables. Operation in slew-rate limited mode

reduces the amplitudes of high-frequency harmonics.

18 ______________________________________________________________________________________

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