Datasheet

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SN75177B, SN75178B

DIFFERENTIAL BUS REPEATERS

SLLS002C – D2606, JULY 1985 – REVISED FEBRUARY 1993

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

2–1

• Meets EIA Standards RS-422-A and RS-485

and CCITT Recommendations V.11 and X.27

• Designed for Multipoint Transmission on

Long Bus Lines in Noisy Environments

• 3-State Outputs

• Bus Voltage Range . . . –7 V to 12 V

• Positive and Negative Current Limiting

• Driver Output Capability . . . 60 mA Max

• Driver Thermal Shutdown Protection

• Receiver Input Impedance . . . 12 kΩ Min

• Receiver Input Sensitivity . . . ±200 mV

• Receiver Input Hysteresis . . . 50 mV Typ

• Operates From Single 5-V Supply

• Low Power Requirements

description

The SN75177B and SN75178B differential bus repeaters are monolithic integrated devices each designed for

one-way data communication on multipoint bus transmission lines. These devices are designed for balanced

transmission bus line applications and meet EIA Standard RS-422-A and RS-485 and CCITT

Recommendations V.11 and X.27. Each device is designed to improve the performance of the data

communication over long bus lines. The SN75177B and SN75178B are identical except for the complementary

enable inputs, which allow the devices to be used in pairs for bidirectional communication.

The SN75177B and SN75178B feature positive- and negative-current limiting 3-state outputs for the receiver

and driver. The receiver features high input impedance, input hysteresis for increased noise immunity, and input

sensitivity of ±200 mV over a common-mode input voltage range of –7 V to 12 V. The driver features thermal

shutdown for protection from line fault conditions. Thermal shutdown is designed to occur at a junction

temperature of approximately 150°C. The driver is designed to drive current loads up to 60 mA maximum.

The SN75177B and SN75178B are designed for optimum performance when used on transmission buses

employing the SN75172 and SN75174 differential line drivers, SN75173 and SN75175 differential line

receivers, or SN75176B bus transceiver.

Function Tables

SN75177B

DIFFERENTIAL INPUTS

ENABLE OUTPUTS

A – B EN T Y Z

≥ 0.2 V H H H L

–0.2 V < V

< 0.2 V H ? ??

≤ 0.2 V H L LH

X L ZZZ

SN75178B

DIFFERENTIAL INPUTS

ENABLE OUTPUTS

A – B EN T Y Z

≥ 0.2 V L H H L

–0.2 V < V

< 0.2 V L ? ??

≤ 0.2 V L L LH

X H ZZZ

H = high level, L = low level, ? = indeterminate, X = irrelevant, Z = impedance (off)

GND

SN75177B ...D OR P PACKAGE

(TOP VIEW)

GND

SN75178B ...P PACKAGE

(TOP VIEW)

THE SN75177B IS NOT

RECOMMENDED FOR NEW DESIGN

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of Texas Instruments

standard warranty. Production processing does not necessarily include

testing of all parameters.

Summary of content (12 pages)

PAGE 1
SN75177B, SN75178B DIFFERENTIAL BUS REPEATERS SLLS002C – D2606, JULY 1985 – REVISED FEBRUARY 1993 • • • • • • • • • • • • SN75177B . . . D OR P PACKAGE (TOP VIEW) Meets EIA Standards RS-422-A and RS-485 and CCITT Recommendations V.11 and X.27 Designed for Multipoint Transmission on Long Bus Lines in Noisy Environments 3-State Outputs Bus Voltage Range . . . – 7 V to 12 V Positive and Negative Current Limiting Driver Output Capability . . .
PAGE 2
SN75177B, SN75178B DIFFERENTIAL BUS REPEATERS SLLS002C – D2606, JULY 1985 – REVISED FEBRUARY 1993 logic symbols† logic diagrams (positive logic) SN75177B SN75177B EN A B T 3 8 EN EN 5 6 7 2 A Y B Z T A B T 3 8 8 5 7 6 2 Receiver EN EN 5 7 6 2 A Y B Z T 3 8 5 7 6 2 Receiver Driver schematics of inputs and outputs EQUIVALENT OF EACH INPUT TYPICAL OF ALL DRIVER OUTPUTS VCC VCC Req Input Output Driver input: Req = 3 kΩ NOM GND Enable inputs: Req = 8 kΩ NOM EQUIVALENT OF EAC
PAGE 3
SN75177B, SN75178B DIFFERENTIAL BUS REPEATERS SLLS002C – D2606, JULY 1985 – REVISED FEBRUARY 1993 absolute maximum ratings over operating free-air temperature range (unless otherwise noted) Supply voltage, VCC (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V Voltage range at any bus terminal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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SN75177B, SN75178B DIFFERENTIAL BUS REPEATERS SLLS002C – D2606, JULY 1985 – REVISED FEBRUARY 1993 DRIVER SECTION electrical characteristics over recommended ranges of supply voltage and operating free-air temperature (unless otherwise noted) PARAMETER TEST CONDITIONS VIK VO Input clamp voltage Output voltage II = – 18 mA IO = 0 |VOD1| Differential output voltage IO = 0 |VOD2| Differential output voltage |VOD3| Differential output voltage ∆|VOD| Change g in magnitude g of diferential output vol
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SN75177B, SN75178B DIFFERENTIAL BUS REPEATERS SLLS002C – D2606, JULY 1985 – REVISED FEBRUARY 1993 SYMBOL EQUIVALENTS DATA SHEET PARAMETER RS-422-A RS-485 VO |VOD1| Voa, Vob Vo Voa, Vob Vo |VOD2| Vt (RL = 100 Ω) Vt (RL = 54 Ω) Vt (Test Termination) Measurement 2) ∆|VOD| | |Vt| – |Vt|| | |Vt| – |Vt|| VOC ∆|VOC| IOS |VOS| |VOS – VOS| |VOS| |VOS – VOS| IO |Ixa|,|Ixb| |VOD3| |Isa|,|Isb| Iia,Iib RECEIVER SECTION electrical characteristics over recommended ranges of common-mode input voltage, s
PAGE 6
SN75177B, SN75178B DIFFERENTIAL BUS REPEATERS SLLS002C – D2606, JULY 1985 – REVISED FEBRUARY 1993 PARAMETER MEASUREMENT INFORMATION RL VOD2 2 VID RL 2 VOH VOC +IOL VOL Figure 1. Driver VOD and VOC – IOH Figure 2. Receiver VOH and VOL 3V Input Generator (see Note A) RL = 54 Ω 50 Ω 1.5 V CL = 50 pF (see Note B) 1.5 V 0V tdD tdD Output Output 90% 50% ≈ 2.5 V 50% 10% ≈ – 2.5 V ttD VOLTAGE WAVEFORMS ttD TEST CIRCUIT Figure 3.
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SN75177B, SN75178B DIFFERENTIAL BUS REPEATERS SLLS002C – D2606, JULY 1985 – REVISED FEBRUARY 1993 PARAMETER MEASUREMENT INFORMATION 3V Input Generator (see Note A) 1.5 V Output 50 Ω 1.5 V 0V 1.5 V CL = 15 pF (see Note B) tPHL tPLH VOH Output 1.3 V 1.3 V VOL TEST CIRCUIT VOLTAGE WAVEFORMS Figure 6. Receiver Propagation Delay Times S1 1.5 V Output S2 2 kΩ –1.
PAGE 8
SN75177B, SN75178B DIFFERENTIAL BUS REPEATERS SLLS002C – D2606, JULY 1985 – REVISED FEBRUARY 1993 TYPICAL CHARACTERISTICS DRIVER HIGH-LEVEL OUTPUT VOLTAGE vs HIGH-LEVEL OUTPUT CURRENT DRIVER LOW-LEVEL OUTPUT VOLTAGE vs LOW-LEVEL OUTPUT CURRENT 5 5 VCC = 5 V TA = 25°C 4 3.5 3 2.5 2 ÁÁ ÁÁ ÁÁ 1.5 1 VCC = 5 V TA = 25°C 4.5 VOH – High-Level Output Voltage – V VOH – High-Level Output Voltage – V 4.5 4 3.5 3 2.5 2 ÁÁÁ ÁÁÁ ÁÁÁ 1.5 1 0.5 0.
PAGE 9
SN75177B, SN75178B DIFFERENTIAL BUS REPEATERS SLLS002C – D2606, JULY 1985 – REVISED FEBRUARY 1993 TYPICAL CHARACTERISTICS RECEIVER HIGH-LEVEL OUTPUT VOLTAGE vs HIGH-LEVEL OUTPUT CURRENT RECEIVER HIGH-LEVEL OUTPUT VOLTAGE vs FREE-AIR TEMPERATURE 5 VID = 0.2 V TA = 25°C VOH – High-Level Output Voltage – V VOH – High-Level Output Voltage – V 5 4 3 VCC = 5.25 V 2 ÁÁ ÁÁ ÁÁ VCC = 5 V VCC = 4.
PAGE 10
SN75177B, SN75178B DIFFERENTIAL BUS REPEATERS SLLS002C – D2606, JULY 1985 – REVISED FEBRUARY 1993 APPLICATION INFORMATION 1/2 SN75179B Direction RT RT Control SN75177B 1/2 SN75179B SN75176B SN75176B RT RT RT RT SN75178B SN75176B NOTE: The line should be terminated at both ends in its characteristic impedance. Stub lengths off the main line should be kept as short as possible. Figure 16.
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