MAX491EESD-T Equivalent & Substitute Parts

Part Overview

The MAX491EESD-T is a full-duplex RS422/RS485 transceiver IC manufactured by Analog Devices Inc./Maxim Integrated in a 14-SOIC surface mount package. This part is classified as obsolete, with 1003 units currently in stock. Due to its obsolete status, identifying equivalent and substitute parts is necessary for design continuity, long-term supply chain planning, and new production runs. Substitute parts must maintain functional compatibility across RS422/RS485 protocol support, electrical performance parameters, and mechanical packaging requirements.

Key Parameters

Parameter	MAX491EESD-T
Manufacturer	Analog Devices Inc./Maxim Integrated
Type	Transceiver
Protocol	RS422, RS485
Number of Drivers/Receivers	1/1
Duplex	Full
Receiver Hysteresis	70 mV
Data Rate	2.5 Mbps
Voltage - Supply	4.75V ~ 5.25V
Operating Temperature	-40°C ~ 85°C
Mounting Type	Surface Mount
Package / Case	14-SOIC (0.154", 3.90mm Width)
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)
REACH Status	REACH Unaffected

Substitute Part Grouping Explanation

Substitute parts for the MAX491EESD-T are grouped based on strict adherence to the following critical parameters:

Primary Substitution Criteria:

Protocol support: RS422 and RS485
Driver/Receiver configuration: 1/1 (single driver, single receiver)
Duplex mode: Full-duplex operation
Package type: 14-SOIC surface mount
Supply voltage range: Compatible with 4.75V ~ 5.25V or broader ranges
Operating temperature range: -40°C ~ 85°C minimum
RoHS3 compliance and MSL 1 rating

Secondary Compatibility Factors:

Receiver hysteresis: 70 mV (primary specification); alternatives with different hysteresis values (20 mV, 25 mV, 150 mV) are listed as substitutes with noted parameter differences
Data rate: 2.5 Mbps (primary); higher data rates (20 Mbps, 52 Mbps) and lower rates (250 kbps) are acceptable for backward compatibility
Product status: Active parts are preferred over obsolete or "Not For New Designs" classifications

Substitutes are organized into two categories: parametric equivalents (identical electrical specifications with different packaging) and manufacturer-recommended alternatives (functionally compatible with minor parameter variations).

Parameter Comparison

Part Number	Manufacturer	Product Status	Protocol	Drivers/Receivers	Data Rate	Receiver Hysteresis	Supply Voltage	Operating Temp	Package	RoHS Status
MAX491EESD-T	Analog Devices Inc./Maxim Integrated	Obsolete	RS422, RS485	1/1	2.5 Mbps	70 mV	4.75V ~ 5.25V	-40°C ~ 85°C	14-SOIC	ROHS3 Compliant
MAX491EESD+T	Analog Devices Inc./Maxim Integrated	Active	RS422, RS485	1/1	2.5 Mbps	70 mV	4.75V ~ 5.25V	-40°C ~ 85°C	14-SOIC	ROHS3 Compliant
MAX491ESD+T	Analog Devices Inc./Maxim Integrated	Active	RS422, RS485	1/1	2.5 Mbps	70 mV	4.75V ~ 5.25V	-40°C ~ 85°C	14-SOIC	ROHS3 Compliant
ADM489ARZ-REEL	Analog Devices Inc.	Not For New Designs	RS422, RS485	1/1	250 kbps	70 mV	4.5V ~ 5.5V	-40°C ~ 85°C	14-SOIC	ROHS3 Compliant
ADM489ARZ-REEL7	Analog Devices Inc.	Active	RS422, RS485	1/1	250 kbps	70 mV	4.5V ~ 5.5V	-40°C ~ 85°C	14-SOIC	ROHS3 Compliant
LT1791IS#PBF	Analog Devices Inc.	Active	RS422, RS485	1/1	250 kbps	20 mV	4.75V ~ 5.25V	-40°C ~ 85°C	14-SOIC	ROHS3 Compliant
LT1791IS#TRPBF	Analog Devices Inc.	Active	RS422, RS485	1/1	250 kbps	20 mV	4.75V ~ 5.25V	-40°C ~ 85°C	14-SOIC	ROHS3 Compliant
LTC1687IS#PBF	Analog Devices Inc.	Active	RS422, RS485	1/1	52 Mbps	25 mV	4.75V ~ 5.25V	-40°C ~ 85°C	14-SOIC	ROHS3 Compliant
LTC1687IS#TRPBF	Analog Devices Inc.	Active	RS422, RS485	1/1	52 Mbps	25 mV	4.75V ~ 5.25V	-40°C ~ 85°C	14-SOIC	ROHS3 Compliant
LTC2864CS-1#PBF	Analog Devices Inc.	Active	RS422, RS485	1/1	20 Mbps	150 mV	3V ~ 5.5V	0°C ~ 70°C	14-SOIC	ROHS3 Compliant
LTC2864CS-1#TRPBF	Analog Devices Inc.	Active	RS422, RS485	1/1	20 Mbps	150 mV	3V ~ 5.5V	0°C ~ 70°C	14-SOIC	ROHS3 Compliant

Engineering Selection Recommendations

Preferred Substitutes (Parametric Equivalents):

MAX491EESD+T and MAX491ESD+T are direct parametric equivalents with identical electrical specifications and active product status. These parts are the primary recommendation for replacing the obsolete MAX491EESD-T in new designs and production runs. Both maintain the 2.5 Mbps data rate, 70 mV receiver hysteresis, and 4.75V ~ 5.25V supply voltage range. Inventory availability is significantly higher (3800 and 12600 units respectively), supporting long-term supply chain requirements.

Secondary Substitutes (Manufacturer-Recommended Alternatives):

ADM489ARZ-REEL7 is an active manufacturer-recommended alternative with identical receiver hysteresis (70 mV) and operating temperature range. The slightly broader supply voltage range (4.5V ~ 5.5V) provides additional design flexibility. The reduced data rate (250 kbps) is acceptable for applications not requiring 2.5 Mbps performance.

LT1791IS#PBF and LT1791IS#TRPBF are active alternatives with tighter receiver hysteresis (20 mV) and identical supply voltage specifications. These parts support lower data rates (250 kbps) and are suitable for noise-sensitive applications where reduced hysteresis improves signal integrity.

LTC1687IS#PBF and LTC1687IS#TRPBF offer significantly higher data rate capability (52 Mbps) with tighter receiver hysteresis (25 mV). These parts are appropriate for high-speed applications requiring enhanced performance margins beyond the original 2.5 Mbps specification.

Conditional Substitutes:

LTC2864CS-1#PBF and LTC2864CS-1#TRPBF support lower operating temperatures (0°C minimum vs. -40°C) and narrower supply voltage range (3V ~ 5.5V). These parts are suitable only for applications within the 0°C ~ 70°C operating window and are not recommended for designs requiring the full -40°C ~ 85°C temperature range of the original part.

All substitute parts maintain ROHS3 compliance and MSL 1 rating, ensuring regulatory and environmental compatibility with the original MAX491EESD-T.

Frequently Asked Questions (FAQ)

Q: Can MAX491EESD+T and MAX491ESD+T be used as direct replacements for MAX491EESD-T?

A: Yes. Both parts are parametric equivalents with identical electrical specifications, protocol support (RS422/RS485), driver/receiver configuration (1/1), duplex mode (full), package type (14-SOIC), supply voltage range (4.75V ~ 5.25V), operating temperature range (-40°C ~ 85°C), and receiver hysteresis (70 mV). The primary difference is product status: MAX491EESD+T and MAX491ESD+T are active, while MAX491EESD-T is obsolete. Both are suitable for new designs and production applications.

Q: What is the difference between the various LTC and ADM substitute parts?

A: Substitute parts differ in data rate capability, receiver hysteresis, and product status. ADM489ARZ-REEL7 maintains the 70 mV hysteresis specification with a lower 250 kbps data rate and active status. LT1791 series parts offer tighter hysteresis (20 mV) at 250 kbps, suitable for noise-sensitive applications. LTC1687 series parts provide the highest data rate (52 Mbps) with 25 mV hysteresis for high-speed designs. LTC2864 series parts operate at 20 Mbps with 150 mV hysteresis but have a narrower temperature range (0°C ~ 70°C).

Q: Are packaging differences between substitute parts significant?

A: All substitute parts use the 14-SOIC surface mount package, ensuring mechanical and electrical compatibility with PCB layouts designed for MAX491EESD-T. Packaging variants (tube, cut tape, tape & reel) affect handling and supply chain logistics but do not impact electrical performance or board-level integration. Select packaging based on production volume and assembly requirements.

Q: Can LTC2864 series parts replace MAX491EESD-T in all applications?

A: No. LTC2864 series parts have a narrower operating temperature range (0°C ~ 70°C vs. -40°C ~ 85°C) and higher receiver hysteresis (150 mV vs. 70 mV). These parts are suitable only for applications operating within 0°C ~ 70°C and where the increased hysteresis does not compromise signal integrity. Applications requiring the full -40°C ~ 85°C temperature range must use MAX491EESD+T, MAX491ESD+T, or ADM489ARZ-REEL7.

Q: What is receiver hysteresis and why does it matter for substitution?

A: Receiver hysteresis is the voltage difference between the rising and falling threshold levels of the input comparator. Lower hysteresis (20 mV, 25 mV) provides tighter noise margins and improved signal integrity in clean environments. Higher hysteresis (70 mV, 150 mV) provides greater noise immunity in electrically noisy environments. Substitution is acceptable when the application environment matches the hysteresis specification of the selected part.

Q: Which substitute part should I select for new designs?

A: For new designs requiring identical performance to MAX491EESD-T, select MAX491ESD+T (12600 units in stock) or MAX491EESD+T (3800 units in stock). Both are active, parametrically equivalent, and have superior inventory availability. For applications requiring higher data rates, select LTC1687IS#PBF or LTC1687IS#TRPBF (52 Mbps capability). For noise-sensitive applications, select LT1791IS#PBF or LT1791IS#TRPBF (20 mV hysteresis).

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