MAX491ECPD RS422/RS485 Transceiver Equivalent & Substitute Parts

Part Overview

The MAX491ECPD is a 1/1 full-duplex RS422/RS485 transceiver manufactured by Analog Devices Inc./Maxim Integrated in a 14-DIP package. This component is classified as obsolete, which necessitates identification of active equivalent and substitute parts for new designs and ongoing production support. The MAX491ECPD operates at 2.5 Mbps data rate with 70 mV receiver hysteresis and is rated for 0°C to 70°C operating temperature range. Equivalent parts maintain identical electrical and mechanical specifications, while substitute parts may vary in specific parameters within acceptable ranges for RS422/RS485 applications.

Substiute Parts

MAX491ECPD

Analog Devices Inc./Maxim IntegratedIn Stock: 5414MAX491ECPD Datasheet

Current PartRFQ

MAX491CPD+

Analog Devices Inc./Maxim IntegratedIn Stock: 2034MAX491CPD+ Datasheet

Parametric EquivalentRFQ

MAX491ECPD+

Analog Devices Inc./Maxim IntegratedIn Stock: 2591MAX491ECPD+ Datasheet

Parametric EquivalentRFQ

LTC491CN#PBF

Analog Devices Inc.In Stock: 2255LTC491CN#PBF Datasheet

DirectRFQ

LT1791ACN#PBF

Analog Devices Inc.In Stock: 1162LT1791ACN#PBF Datasheet

MFR RecommendedRFQ

LT1791CN#PBF

Analog Devices Inc.In Stock: 2923LT1791CN#PBF Datasheet

MFR RecommendedRFQ

LT1791HN#PBF

Analog Devices Inc.In Stock: 792LT1791HN#PBF Datasheet

MFR RecommendedRFQ

LTC491IN#PBF

Analog Devices Inc.In Stock: 2226LTC491IN#PBF Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for RS422/RS485 transceivers is determined by the following critical parameters:

Primary Substitution Criteria:

• Protocol support (RS422, RS485)
• Number of drivers/receivers (1/1 configuration)
• Duplex mode (Full)
• Package type (14-DIP)
• Supply voltage range (4.75V ~ 5.25V)
• Mounting type (Through Hole)

Secondary Variation Parameters (allowable differences):

• Receiver hysteresis (70 mV vs. 20 mV)
• Data rate (2.5 Mbps vs. 250 kbps)
• Operating temperature range (0°C ~ 70°C vs. -40°C ~ 125°C or -40°C ~ 85°C)
• Product status (Obsolete vs. Active)
• RoHS compliance status

Parts are grouped into three categories:

1. Parametric Equivalents - Identical electrical and mechanical specifications with active product status
2. Direct Manufacturer Equivalents - Same base functionality with minor parameter variations
3. Manufacturer Recommended Substitutes - Functionally compatible with documented parameter differences

Parameter Comparison

Engineering Selection Recommendations

For Direct Replacement (Obsolete to Active): MAX491ECPD+ is the primary selection. This part maintains identical electrical specifications (2.5 Mbps, 70 mV hysteresis, 0°C ~ 70°C) while transitioning from obsolete to active product status and achieving ROHS3 compliance. Pinout and package are identical.

For RoHS3 Compliance Requirement: MAX491CPD+ and MAX491ECPD+ both satisfy ROHS3 compliance with identical performance to the original MAX491ECPD. MAX491ECPD+ is preferred due to higher inventory availability (2500 Pcs vs. 2020 Pcs).

For Extended Temperature Range: LTC491IN#PBF extends operating temperature to -40°C ~ 85°C while maintaining 70 mV receiver hysteresis. Data rate specification is not provided but maintains RS422/RS485 protocol compatibility.

For Industrial Temperature Range (-40°C ~ 125°C): LT1791HN#PBF provides the widest operating temperature range. Note that receiver hysteresis reduces to 20 mV and data rate is specified as 250 kbps, representing a lower-speed variant suitable for noise-sensitive or extended-temperature applications.

For Cost Optimization with Reduced Data Rate: LT1791CN#PBF and LT1791ACN#PBF operate at 250 kbps with 20 mV hysteresis. These are applicable only where maximum data rate requirement does not exceed 250 kbps.

Frequently Asked Questions (FAQ)

Q: Can MAX491ECPD+ directly replace MAX491ECPD without PCB modification? A: Yes. MAX491ECPD+ is a parametric equivalent with identical pinout, package (14-DIP), and electrical specifications. No PCB changes are required.

Q: What is the difference between MAX491ECPD+ and MAX491CPD+? A: Both parts are parametric equivalents with identical electrical performance. MAX491ECPD+ has higher inventory (2500 Pcs) and is the preferred selection for direct replacement.

Q: Can LT1791 series parts replace MAX491ECPD? A: LT1791 series parts are manufacturer-recommended substitutes with compatible RS422/RS485 protocols and identical package. However, they operate at reduced data rate (250 kbps vs. 2.5 Mbps) and lower receiver hysteresis (20 mV vs. 70 mV). Selection depends on application data rate requirements.

Q: What is the significance of receiver hysteresis difference (70 mV vs. 20 mV)? A: Receiver hysteresis affects noise immunity. The 70 mV hysteresis of MAX491ECPD provides greater noise margin. The 20 mV hysteresis of LT1791 series is suitable for cleaner signal environments but may require additional filtering in noisy applications.

Q: Are LTC491 parts suitable for high-speed applications? A: LTC491CN#PBF and LTC491IN#PBF maintain 70 mV receiver hysteresis matching the original MAX491ECPD. Data rate is not specified in available documentation. Verify datasheet specifications for applications requiring confirmed 2.5 Mbps operation.

Q: Which substitute part offers the best compliance profile? A: All active substitute parts (MAX491CPD+, MAX491ECPD+, LTC491CN#PBF, LTC491IN#PBF, LT1791 series) are ROHS3 compliant. The original MAX491ECPD is RoHS non-compliant. For new designs, any active substitute meets current compliance requirements.

Q: Can I use LT1791HN#PBF in a 0°C ~ 70°C application? A: Yes. LT1791HN#PBF is rated for -40°C ~ 125°C, which encompasses the 0°C ~ 70°C range. However, this part operates at 250 kbps maximum data rate, which may not be suitable if 2.5 Mbps operation is required.