DS78C20 [NSC]

Dual CMOS Compatible Differential Line Receiver; 双CMOS兼容差动线路接收器


型号：	DS78C20
厂家：	National Semiconductor
描述：	Dual CMOS Compatible Differential Line Receiver 双CMOS兼容差动线路接收器
文件：	总6页 (文件大小：112K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

May 1998

DS78C20/DS88C20

Dual CMOS Compatible Differential Line Receiver

General Description

Features

n Meets requirements of EIA Standards RS-232-C RS-422

The DS78C20 and DS88C20 are high performance, dual dif-

ferential, CMOS compatible line receivers for both balanced

and unbalanced digital data transmission. The inputs are

compatible with EIA and Federal Standards.

and RS-423, and Federal Standards 1020 and 1030

n Input voltage range of 15V (differential or

common-mode)

n Separate strobe input for each receiver

Input specifications meet or exceed those of the popular

DS7820/DS8820 line receiver, and the pinout is identical.

⁄2 V_CCstrobe threshold for CMOS compatibility

n 5k typical input impedance

n 50 mV input hysteresis

n 200 mV input threshold

A response pin is provided for controlling sensitivity to input

noise spikes with an external capacitor. Each receiver in-

cludes a 180Ω terminating resistor, which may be used op-

tionally on twisted pair lines. The DS78C20 is specified over

a −55˚C to +125˚C operating temperature range, and the

DS88C20 over a 0˚C to +70˚C range.

n Operation voltage range 4.5V to 15V

n DS7830/DS8830 recommended driver

Connection Diagram

Dual-In-Line Package

DS005798-1

Top View

Order Number DS88C20N

See NS Package Numbers N14A

For Complete Military Product Specifications,

refer to the appropriate SMD or MDS.

Order Number DS78C20J/883

See NS Package Number J14A

DS005798

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Absolute Maximum Ratings (Note 2)

Lead Temperature (Soldering, 4 seconds)

260˚C

If Military/Aerospace specified devices are required,

please contact the National Semiconductor Sales Office/

Distributors for availability and specifications.

Operating Conditions

Min

Max

Units

Supply Voltage

18V

25V

18V

Supply Voltage (V_CC

Temperature (T_A)

DS78C20

)

4.5

Common-Mode Voltage

Differential Input Voltage

Strobe Voltage

−55

+125

+70

˚C

DS88C20

Output Sink Current

50 mA

Common-Mode Voltage (V_CM

)

−15

+15

Maximum Power Dissipation (Note 1) at 25˚C

Cavity Package

Note 1: Derate cavity package 9.1 mW/˚C; derate molded package 10.2

mW/˚C above 25˚C.

1364 mW

1280 mW

Molded Package

Storage Temperature Range

−65˚C to

+150˚C

Electrical Characteristics (Notes 3, 4)

Symbol

Parameter

Differential Threshold

Voltage

Conditions

Min

Typ

0.06

−0.08

Max Units

V_TH

I_OUT−200 µA,

−10V ≤ V_CM≤ 10V

−15V ≤ V_CM≤ 15V

−10V ≤ V_CM≤ 10V

−15V ≤ V_CM≤ 15V

0.2

0.3

V_OUT≥ V −1.2V

I_OUT1.6 mA, V_OUT≤ 0.5V

−0.2

−0.3

R_IN

R_T

Input Resistance

−15V ≤ V

≤ 15V

kΩ

Ω

Line Termination

Resistance

T_A25˚C

100

180

300

3.1

I_IND

Data Input Current

(Unterminated)

V_CM10V

V_CM0V

−0.5 mA

−3.1 mA

V_CM−10V

−2

V_THB

Input Balance

I_OUT200 µA, V_OUT

≥

−7V ≤ V_CM≤ 7V

V_CC−1.2V, R

(Note 6)

500Ω,

0.1

0.4

I_OUT1.6 mA, V_OUT≤ 0.5V, −7V ≤ V_CM≤ 7V

−0.1

−0.4

R_S500Ω, (Note 6)

V_OH

V_OL

I_CC

Logical “1” Output Voltage I_OUT−200 µA, V_DIFF1V

V_CC−1.2

V_CC−0.75

Logical “0” Output Voltage I_OUT1.6 mA, V_DIFF−1V

0.25

0.5

Power Supply Current

15V ≤ V_CM≤ −15V,

V_CC5.5V

V_DIFF−0.5V

V_CC15V

(Both Receivers)

I_IN(1)

I_IN(0)

V_IH

Logical “1” Strobe Input

Current

V_STROBE15V, V_DIFF3V

V_CC15V

100

µA

Logical “0” Strobe Input

Current

V_STROBE0V, V_DIFF−3V

V_CC15V

−0.5

−100

Logical “1” Strobe Input

Voltage

I_OUT1.6 mA, V_OL≤ 0.5V

V_CC5V

3.5

8.0

2.5

5.0

7.5

2.5

5.0

7.5

−20

V_CC10V

V_CC15V

12.5

V_IL

Logical “0” Strobe Input

Voltage

I_OUT−200 µA,

V_CC5V

1.5

2.0

2.5

V_CC10V

V_OHV_CC−1.2V

V_CC15V

I_OS

Output Short-Circuit

Current

0V, V_CC15V, V_STROBE0V, (Note 5)

−5

−40 mA

OUT

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Switching Characteristics

V_CC5V, T_A25˚C

Symbol

Parameter

Conditions

Min

Typ

Max

100

150

Units

C_L50 pF

t_pd0(D)

t_pd1(D)

t_pd0(S)

t_pd1(S)

Differential Input to “0” Output

Differential Input to “1” Output

Strobe Input to “0” Output

Strobe Input to “1” Output

C_L50 pF

100

C_L50 pF

100

150

Note 2: “Absolute Maximum Ratings” are those values beyond which the safety of the device cannot be guaranteed. Except for “Operating Temperature Range” they

are not meant to imply that the devices should be operated at these limits. The table of “Electrical Characteristics” provides conditions for actual device operation.

Note 3: Unless otherwise specified min/max limits apply across the −55˚C to +125˚C temperature range for the DS78C20 and across the 0˚C to +70˚C range for the

5V and V 0V.

DS88C20. All typical values are for T

25˚C, V

Note 4: All currents into device pins shown as positive, out of device pins as negative, all voltages referenced to ground unless otherwise noted. All values shown

as max or min on absolute value basis.

Note 5: Only one output at a time should be shorted.

Note 6: Refer to EIA-RS-422 for exact conditions.

Typical Applications

RS-422/RS-423 Application

DS005798-2

Note 7: (Optional internal termination resistor.)

a) Capacitor in series with internal line termination resistor, terminates the line and saves termination power. Exact value depends on line length.

b) Pin 1 connected to pin 2; terminates the line.

c) Pin 2 open; no internal line termination.

d) Transmission line may be terminated elsewhere or not at all.

Note 8: Optional to control response time.

Note 9:

4.5V to 15V for the DS78C20. For further information on line drivers and line receivers, refer to applicaton notes AN-22, AN-83 and AN-108.

RS-232-C Application with Hysteresis

DS005798-4

DS005798-3

For signals which require fail-safe or have slow rise and fall times, use R1

and D1 as shown above. Otherwise, the positive input (pin 3 or 11) may be

connected to ground.

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Typical Applications (Continued)

V_CC

R1 5%

4,3 kΩ

15 kΩ

24 kΩ

10V

15V

AC Test Circuit

DS005798-5

≤ 10 ns

PRR 1 MHz

Note 10: Includes probe and jig capacitance

Switching Time Waveforms

DS005798-6

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Physical Dimensions inches (millimeters) unless otherwise noted

Ceramic Dual-In-Line Package (J)

Order Number DS78C20J/883

NS Package Number J14A

Molded Dual-In-Line Package (N)

Order Number DS88C20N

NS Package Number N14A

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CONDUCTOR CORPORATION. As used herein:

1. Life support devices or systems are devices or sys-

tems which, (a) are intended for surgical implant into

the body, or (b) support or sustain life, and whose fail-

ure to perform when properly used in accordance

with instructions for use provided in the labeling, can

be reasonably expected to result in a significant injury

to the user.

2. A critical component in any component of a life support

device or system whose failure to perform can be rea-

sonably expected to cause the failure of the life support

device or system, or to affect its safety or effectiveness.

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Tel: 1-800-272-9959

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