MAX491CSD Equivalent & Substitute Parts

Part Overview

The MAX491CSD is a full-duplex RS422/RS485 transceiver manufactured by Analog Devices Inc./Maxim Integrated, housed in a 14-SOIC surface mount package. This component is classified as obsolete, with 1818 units available in new original stock. The MAX491CSD operates as a 1/1 transceiver (one driver and one receiver pair) and is designed for industrial communication applications requiring reliable serial data transmission over twisted-pair cabling.

Due to its obsolete product status, identifying equivalent and substitute parts is essential for design continuity, system upgrades, and long-term supply chain planning. Equivalent parts maintain identical electrical and mechanical specifications, while substitute parts offer compatible functionality with potential variations in performance characteristics or operating conditions.

Key Parameters

Parameter	MAX491CSD
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	0°C ~ 70°C
Mounting Type	Surface Mount
Package / Case	14-SOIC (0.154", 3.90mm Width)
RoHS Status	RoHS non-compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the MAX491CSD is determined by strict adherence to the following electrical and mechanical parameters:

Critical Parameters for Direct Substitution:

Protocol: RS422/RS485 full-duplex operation
Driver/Receiver Configuration: 1/1 topology
Package Type: 14-SOIC surface mount form factor
Supply Voltage Range: 4.75V to 5.25V compatibility
Operating Temperature Range: 0°C to 70°C minimum
Receiver Hysteresis: 70 mV specification
Data Rate: 2.5 Mbps minimum capability

Grouping Categories:

Group 1 - Parametric Equivalents (Identical Specifications): Parts that maintain all electrical parameters and package specifications of the MAX491CSD while offering improved product status or compliance certifications.

Group 2 - Direct Manufacturer Equivalents (LTC Series): Parts from Analog Devices Inc. with identical electrical specifications but alternative packaging options (Tube vs. Tape & Reel).

Group 3 - MFR Recommended Substitutes (Enhanced Performance): Parts recommended by manufacturers that maintain core RS422/RS485 functionality and 14-SOIC packaging but may offer extended operating temperature ranges, higher data rates, or improved compliance certifications.

Parameter Comparison

Part Number	Manufacturer	Product Status	Protocol	Drivers/Receivers	Data Rate	Supply Voltage	Operating Temp	Receiver Hysteresis	Package	RoHS Status
MAX491CSD	Analog Devices Inc./Maxim	Obsolete	RS422, RS485	1/1	2.5 Mbps	4.75V ~ 5.25V	0°C ~ 70°C	70 mV	14-SOIC	Non-compliant
MAX491CSD+	Analog Devices Inc./Maxim	Active	RS422, RS485	1/1	2.5 Mbps	4.75V ~ 5.25V	0°C ~ 70°C	70 mV	14-SOIC	ROHS3 Compliant
MAX491ECSD+	Analog Devices Inc./Maxim	Active	RS422, RS485	1/1	2.5 Mbps	4.75V ~ 5.25V	0°C ~ 70°C	70 mV	14-SOIC	ROHS3 Compliant
LTC491CS#PBF	Analog Devices Inc.	Active	RS422, RS485	1/1	—	4.75V ~ 5.25V	0°C ~ 70°C	70 mV	14-SOIC	ROHS3 Compliant
LTC491CS#TRPBF	Analog Devices Inc.	Active	RS422, RS485	1/1	—	4.75V ~ 5.25V	0°C ~ 70°C	70 mV	14-SOIC	ROHS3 Compliant
ISL8491EIBZ	Renesas Electronics	Active	RS422, RS485	1/1	10 Mbps	4.5V ~ 5.5V	-40°C ~ 85°C	70 mV	14-SOIC	ROHS3 Compliant
ISL8491EIBZ-T	Renesas Electronics	Active	RS422, RS485	1/1	10 Mbps	4.5V ~ 5.5V	-40°C ~ 85°C	70 mV	14-SOIC	ROHS3 Compliant
LT1791CS#PBF	Analog Devices Inc.	Active	RS422, RS485	1/1	250 kbps	4.75V ~ 5.25V	0°C ~ 70°C	20 mV	14-SOIC	ROHS3 Compliant
LT1791CS#TRPBF	Analog Devices Inc.	Active	RS422, RS485	1/1	250 kbps	4.75V ~ 5.25V	0°C ~ 70°C	20 mV	14-SOIC	ROHS3 Compliant
LTC1687CS#PBF	Analog Devices Inc.	Active	RS422, RS485	1/1	52 Mbps	4.75V ~ 5.25V	0°C ~ 70°C	25 mV	14-SOIC	ROHS3 Compliant
LTC1687CS#TRPBF	Analog Devices Inc.	Active	RS422, RS485	1/1	52 Mbps	4.75V ~ 5.25V	0°C ~ 70°C	25 mV	14-SOIC	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Replacement (Identical Specifications):

MAX491CSD+ and MAX491ECSD+ are the primary direct replacements. Both parts maintain identical electrical specifications (2.5 Mbps data rate, 70 mV receiver hysteresis, 4.75V–5.25V supply voltage, 0°C–70°C operating range) and 14-SOIC packaging. Both are active products with ROHS3 compliance, addressing the obsolescence of the original MAX491CSD. MAX491CSD+ is available in Tube packaging with 15,823 units in stock, while MAX491ECSD+ is also in Tube packaging with 14,523 units in stock.

For Supply Chain Continuity with Enhanced Compliance:

LTC491CS#PBF and LTC491CS#TRPBF (Analog Devices Inc.) maintain identical electrical specifications and 14-SOIC packaging. These parts are active products with ROHS3 compliance. LTC491CS#PBF is available in Tube packaging (1,127 units), while LTC491CS#TRPBF is available in Tape & Reel packaging (2,022 units). Data rate specification is not provided for these parts, but electrical parameters align with the MAX491CSD.

For Extended Operating Range Applications:

ISL8491EIBZ and ISL8491EIBZ-T (Renesas Electronics Corporation) are manufacturer-recommended substitutes offering extended operating temperature range (-40°C to 85°C versus 0°C to 70°C) and higher data rate capability (10 Mbps versus 2.5 Mbps). Supply voltage range is slightly broader (4.5V–5.5V). Both maintain 14-SOIC packaging, 1/1 driver/receiver configuration, and ROHS3 compliance. ISL8491EIBZ is available in Tube packaging (2,651 units), while ISL8491EIBZ-T is available in Cut Tape & Digi-Reel packaging (2,600 units).

For High-Speed Applications:

LTC1687CS#PBF and LTC1687CS#TRPBF (Analog Devices Inc.) support 52 Mbps data rate, significantly exceeding the MAX491CSD specification. These parts maintain 14-SOIC packaging, 1/1 configuration, and ROHS3 compliance. Operating temperature and supply voltage specifications match the original part. LTC1687CS#PBF is available in Tube packaging (2,502 units), while LTC1687CS#TRPBF is available in Tape & Reel packaging (1,498 units).

For Low-Speed, Low-Hysteresis Applications:

LT1791CS#PBF and LT1791CS#TRPBF (Analog Devices Inc.) are suitable for applications where lower receiver hysteresis (20 mV versus 70 mV) is beneficial and data rate requirements are modest (250 kbps). These parts maintain 14-SOIC packaging, 1/1 configuration, and ROHS3 compliance. LT1791CS#PBF is available in Tube packaging (1,136 units), while LT1791CS#TRPBF is available in Tape & Reel packaging (1,364 units).

Frequently Asked Questions (FAQ)

Q: Can MAX491CSD+ be used as a direct drop-in replacement for MAX491CSD?

A: Yes. MAX491CSD+ maintains identical electrical specifications (2.5 Mbps data rate, 70 mV receiver hysteresis, 4.75V–5.25V supply voltage, 0°C–70°C operating temperature) and 14-SOIC packaging. The primary difference is product status (Active versus Obsolete) and RoHS compliance (ROHS3 Compliant versus non-compliant). Pin configuration and functional behavior are identical.

Q: What is the difference between MAX491CSD+ and MAX491ECSD+?

A: Both parts are parametric equivalents with identical electrical specifications and 14-SOIC packaging. The designation difference (CSD+ versus ECSD+) reflects internal manufacturing or qualification variations within Analog Devices Inc./Maxim Integrated product lines. Both are active products with ROHS3 compliance and equivalent inventory availability.

Q: Can LTC491CS parts be substituted for MAX491CSD?

A: Yes, with the caveat that data rate specification is not provided for LTC491CS parts. All other electrical parameters (receiver hysteresis, supply voltage, operating temperature) and mechanical specifications (14-SOIC packaging, 1/1 configuration) are identical. LTC491CS parts are active products with ROHS3 compliance.

Q: What are the advantages of ISL8491EIBZ over MAX491CSD?

A: ISL8491EIBZ offers extended operating temperature range (-40°C to 85°C versus 0°C to 70°C), higher data rate capability (10 Mbps versus 2.5 Mbps), and slightly broader supply voltage tolerance (4.5V–5.5V versus 4.75V–5.25V). These enhancements make ISL8491EIBZ suitable for industrial and automotive applications requiring wider temperature operation. Receiver hysteresis remains at 70 mV, and 14-SOIC packaging is maintained.

Q: When should LTC1687CS be considered instead of MAX491CSD?

A: LTC1687CS is appropriate for applications requiring significantly higher data rates (52 Mbps versus 2.5 Mbps). If your system operates at or near the 2.5 Mbps limit of MAX491CSD and future bandwidth expansion is anticipated, LTC1687CS provides substantial headroom. Operating temperature and supply voltage specifications remain compatible with MAX491CSD. Receiver hysteresis is 25 mV (versus 70 mV), which may affect noise immunity in electrically noisy environments.

Q: What packaging options are available for substitute parts?

A: Most substitute parts are available in multiple packaging formats: Tube (standard reel packaging for manual assembly), Tape & Reel (TR) for automated pick-and-place assembly, and Cut Tape & Digi-Reel for mixed-volume applications. Part number suffixes indicate packaging: #PBF denotes Tube, #TRPBF denotes Tape & Reel, and -T denotes Cut Tape & Digi-Reel. Select packaging based on assembly process requirements and order volume.

Q: Are all substitute parts RoHS compliant?

A: All substitute parts listed are ROHS3 compliant. The original MAX491CSD is RoHS non-compliant. If your application or supply chain requires RoHS compliance, any of the listed substitute parts satisfy this requirement.

Q: Can LT1791CS be used if lower receiver hysteresis is required?

A: Yes. LT1791CS provides 20 mV receiver hysteresis compared to 70 mV for MAX491CSD. Lower hysteresis improves sensitivity to small signal changes but may increase susceptibility to noise in electrically noisy environments. LT1791CS maintains identical supply voltage (4.75V–5.25V), operating temperature (0°C–70°C), and 14-SOIC packaging. Data rate is specified at 250 kbps, which is lower than MAX491CSD's 2.5 Mbps.

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