DS485N RS422/RS485 Half-Duplex Transceiver Equivalent & Substitute Parts

Part Overview

The DS485N is a half-duplex RS422/RS485 transceiver manufactured by Texas Instruments, housed in an 8-PDIP package. This interface IC operates at 2.5 Mbps data rate with a 70 mV receiver hysteresis and supports supply voltages from 4.75V to 5.25V. The DS485N is classified as obsolete, making equivalent and substitute parts necessary for ongoing system maintenance, redesigns, and new production runs. Active alternatives from Analog Devices Inc. and Maxim Integrated provide compatible functionality with improved product status and compliance certifications.

Key Parameters

Parameter	DS485N Value
Manufacturer	Texas Instruments
Product Status	Obsolete
Type	Transceiver
Protocol	RS422, RS485
Number of Drivers/Receivers	1/1
Duplex	Half
Receiver Hysteresis	70 mV
Data Rate	2.5 Mbps
Voltage - Supply	4.75V ~ 5.25V
Operating Temperature	0°C ~ 70°C
Mounting Type	Through Hole
Package / Case	8-DIP (0.300", 7.62mm)
RoHS Status	RoHS non-compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the DS485N is determined by strict adherence to the following electrical and mechanical parameters:

Primary Compatibility Criteria:

Protocol: RS422/RS485 half-duplex operation
Number of Drivers/Receivers: 1/1 configuration
Package: 8-DIP (0.300", 7.62mm) through-hole mounting
Supply Voltage Range: 4.75V ~ 5.25V (must encompass or match the original range)
Receiver Hysteresis: 70 mV (preferred for direct substitution)
Data Rate: 2.5 Mbps minimum (original specification)

Grouping Logic:

Group 1 - Direct Electrical Equivalents (Preferred): Parts matching all primary criteria including 70 mV hysteresis and 2.5 Mbps data rate with active product status and RoHS3 compliance.

Group 2 - Enhanced Performance Alternatives: Parts with superior data rate (5 Mbps) or extended temperature range (-40°C ~ 85°C) while maintaining core electrical parameters and package compatibility.

Group 3 - Specialized Alternatives: Parts with different receiver hysteresis (20 mV or 45 mV) or reduced data rate (250 kbps) for specific application requirements, maintaining package and voltage compatibility.

Parameter Comparison

Part Number	Manufacturer	Product Status	Protocol	Drivers/Receivers	Duplex	Hysteresis (mV)	Data Rate	Supply Voltage	Temp Range	Package	RoHS Status
DS485N	Texas Instruments	Obsolete	RS422, RS485	1/1	Half	70	2.5 Mbps	4.75V ~ 5.25V	0°C ~ 70°C	8-DIP	Non-compliant
MAX481EPA+	Analog Devices Inc./Maxim Integrated	Active	RS422, RS485	1/1	Half	70	2.5 Mbps	4.75V ~ 5.25V	-40°C ~ 85°C	8-DIP	ROHS3 Compliant
MAX485EPA+	Analog Devices Inc./Maxim Integrated	Active	RS422, RS485	1/1	Half	70	2.5 Mbps	4.75V ~ 5.25V	-40°C ~ 85°C	8-DIP	ROHS3 Compliant
ADM485ANZ	Analog Devices Inc.	Active	RS422, RS485	1/1	Half	70	5 Mbps	4.75V ~ 5.25V	-40°C ~ 85°C	8-DIP	ROHS3 Compliant
ADM485JNZ	Analog Devices Inc.	Active	RS422, RS485	1/1	Half	70	5 Mbps	4.75V ~ 5.25V	0°C ~ 70°C	8-DIP	ROHS3 Compliant
LT1785AIN8#PBF	Analog Devices Inc.	Active	RS422, RS485	1/1	Half	20	250 kbps	4.75V ~ 5.25V	-40°C ~ 85°C	8-DIP	ROHS3 Compliant
LT1785IN8#PBF	Analog Devices Inc.	Active	RS422, RS485	1/1	Half	20	250 kbps	4.75V ~ 5.25V	-40°C ~ 85°C	8-DIP	ROHS3 Compliant
LTC1481CN8#PBF	Analog Devices Inc.	Active	RS422, RS485	1/1	Half	45	2.5 Mbps	4.75V ~ 5.25V	0°C ~ 70°C	8-DIP	ROHS3 Compliant
LTC485CN8#PBF	Analog Devices Inc.	Active	RS422, RS485	1/1	Half	70	Not specified	4.75V ~ 5.25V	0°C ~ 70°C	8-DIP	ROHS3 Compliant
LTC485IN8#PBF	Analog Devices Inc.	Active	RS422, RS485	1/1	Half	70	Not specified	4.75V ~ 5.25V	-40°C ~ 85°C	8-DIP	ROHS3 Compliant
MAX1487EPA+	Analog Devices Inc./Maxim Integrated	Active	RS422, RS485	1/1	Half	70	2.5 Mbps	4.75V ~ 5.25V	-40°C ~ 85°C	8-DIP	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Replacement (Identical Electrical Performance): MAX481EPA+, MAX485EPA+, and MAX1487EPA+ are active, RoHS3-compliant alternatives that maintain the DS485N's 70 mV hysteresis and 2.5 Mbps data rate. These parts are suitable for applications requiring exact electrical equivalence with improved product lifecycle status and regulatory compliance.

For Enhanced Temperature Range Applications: ADM485ANZ and MAX481EPA+ extend the operating temperature range to -40°C ~ 85°C while maintaining 70 mV hysteresis. ADM485ANZ additionally provides 5 Mbps data rate capability. These are appropriate for industrial and extended-temperature environments.

For Matched Temperature Range (0°C ~ 70°C): ADM485JNZ and LTC1481CN8#PBF maintain the original DS485N operating temperature range. ADM485JNZ offers 5 Mbps performance; LTC1481CN8#PBF provides 45 mV hysteresis for applications requiring tighter noise margins.

For Low-Speed, Low-Hysteresis Applications: LT1785AIN8#PBF and LT1785IN8#PBF feature 20 mV receiver hysteresis and 250 kbps data rate, suitable for noise-sensitive, low-speed RS485 networks. These parts are not direct replacements but serve specialized low-speed applications.

For Compliance-Critical Designs: All substitute parts listed carry RoHS3 compliance, addressing regulatory requirements that the obsolete DS485N cannot meet. Selection should prioritize active product status and compliance certifications for new designs and long-term production sustainability.

Frequently Asked Questions (FAQ)

Q: Can MAX485EPA+ directly replace DS485N in existing designs? A: Yes. MAX485EPA+ matches the DS485N's electrical specifications (70 mV hysteresis, 2.5 Mbps data rate, 1/1 driver/receiver configuration) and 8-DIP package. The extended temperature range (-40°C ~ 85°C versus 0°C ~ 70°C) and RoHS3 compliance are improvements. Pin-for-pin compatibility and functional equivalence are confirmed.

Q: What is the difference between MAX481EPA+ and MAX485EPA+? A: Both parts are electrically identical in the parameters provided (70 mV hysteresis, 2.5 Mbps, 1/1 configuration, 8-DIP package, -40°C ~ 85°C range, RoHS3 compliant). Selection between them depends on design preference and inventory availability. Consult manufacturer datasheets for any undocumented functional differences.

Q: Why do some substitute parts show different receiver hysteresis values? A: Receiver hysteresis affects noise immunity and signal detection sensitivity. The DS485N specifies 70 mV. Parts with 20 mV (LT1785 series) or 45 mV (LTC1481CN8#PBF) hysteresis are not direct electrical equivalents and are suitable only for applications where lower hysteresis is acceptable or beneficial. Higher hysteresis provides greater noise immunity; lower hysteresis provides faster signal detection.

Q: Are LT1785 parts suitable replacements for DS485N? A: No. LT1785AIN8#PBF and LT1785IN8#PBF differ significantly: 20 mV hysteresis (versus 70 mV) and 250 kbps data rate (versus 2.5 Mbps). These are specialized low-speed alternatives for applications requiring different electrical characteristics, not direct substitutes.

Q: What does "Data Rate: Not specified" mean for LTC485 parts? A: The data rate specification is not provided in the available technical parameters for LTC485CN8#PBF and LTC485IN8#PBF. These parts maintain 70 mV hysteresis and 8-DIP package compatibility with the DS485N. Consult manufacturer datasheets to confirm data rate capability before selection.

Q: Is the 8-DIP package identical across all listed parts? A: Yes. All parts use 8-DIP (0.300", 7.62mm) through-hole packaging, ensuring mechanical and pin-level compatibility. PCB layout and footprints designed for DS485N are compatible with all listed substitutes.

Q: Why is RoHS compliance important for DS485N replacement? A: The DS485N is RoHS non-compliant. All active substitute parts are RoHS3 compliant, meeting current regulatory requirements for electronics manufacturing and distribution. New designs and production runs should prioritize RoHS-compliant alternatives to ensure market access and regulatory compliance.

Q: Can ADM485ANZ replace DS485N in temperature-sensitive applications? A: ADM485ANZ is suitable for applications requiring extended temperature operation (-40°C ~ 85°C). It maintains 70 mV hysteresis and 8-DIP package compatibility but offers enhanced 5 Mbps data rate. For applications limited to 0°C ~ 70°C, ADM485JNZ provides the same temperature range as DS485N with 5 Mbps capability.

Q: What is the supply voltage compatibility across all parts? A: All listed parts operate within the 4.75V ~ 5.25V supply range, matching the DS485N specification. This ensures direct voltage compatibility in existing power supply designs.

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