ISL8491IBZ Equivalent & Substitute Parts

Part Overview

The ISL8491IBZ is a 1/1 full-duplex RS422/RS485 transceiver manufactured by Renesas Electronics Corporation in a 14-SOIC surface mount package. This interface IC operates across a 4.5V to 5.5V supply range with a maximum data rate of 5Mbps and receiver hysteresis of 70mV. The device is classified as obsolete, making equivalent and substitute parts necessary for ongoing system support and new design implementations.

Key Parameters

Parameter	ISL8491IBZ
Manufacturer	Renesas Electronics Corporation
Type	Transceiver
Protocol	RS422, RS485
Number of Drivers/Receivers	1/1
Duplex	Full
Receiver Hysteresis	70 mV
Data Rate	5 Mbps
Voltage - Supply	4.5V ~ 5.5V
Operating Temperature	-40°C ~ 85°C
Package / Case	14-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution for the ISL8491IBZ is determined by strict alignment of the following electrical and mechanical parameters:

Primary Substitution Criteria:

Protocol compatibility: RS422/RS485 full-duplex transceiver
Configuration: 1/1 drivers/receivers
Package: 14-SOIC surface mount form factor
Supply voltage range overlap with 4.5V ~ 5.5V
Operating temperature range that encompasses or exceeds -40°C ~ 85°C
RoHS3 compliance and REACH unaffected status

Secondary Compatibility Factors:

Data rate capability (minimum 5 Mbps required)
Receiver hysteresis specification
Moisture sensitivity level
Product status (active preferred for long-term availability)

The substitute parts identified below meet the primary criteria and maintain functional equivalence within the specified electrical and mechanical constraints.

Parameter Comparison

Part Number	Manufacturer	Protocol	Drivers/Receivers	Data Rate	Supply Voltage	Operating Temp	Receiver Hysteresis	Package	Product Status	RoHS Status
ISL8491IBZ	Renesas Electronics	RS422, RS485	1/1	5 Mbps	4.5V ~ 5.5V	-40°C ~ 85°C	70 mV	14-SOIC	Obsolete	ROHS3
LT1791ACS#PBF	Analog Devices Inc.	RS422, RS485	1/1	250 kbps	4.75V ~ 5.25V	0°C ~ 70°C	20 mV	14-SOIC	Active	ROHS3
LT1791AHS#PBF	Analog Devices Inc.	RS422, RS485	1/1	250 kbps	4.75V ~ 5.25V	-40°C ~ 125°C	20 mV	14-SOIC	Active	ROHS3
LT1791AIS#PBF	Analog Devices Inc.	RS422, RS485	1/1	250 kbps	4.75V ~ 5.25V	-40°C ~ 85°C	20 mV	14-SOIC	Active	ROHS3
LT1791AIS#TRPBF	Analog Devices Inc.	RS422, RS485	1/1	250 kbps	4.75V ~ 5.25V	-40°C ~ 85°C	20 mV	14-SOIC	Active	ROHS3
LTC2864CS-1#PBF	Analog Devices Inc.	RS422, RS485	1/1	20 Mbps	3V ~ 5.5V	0°C ~ 70°C	150 mV	14-SOIC	Active	ROHS3
LTC2864CS-1#TRPBF	Analog Devices Inc.	RS422, RS485	1/1	20 Mbps	3V ~ 5.5V	0°C ~ 70°C	150 mV	14-SOIC	Active	ROHS3
LTC2864CS-2#PBF	Analog Devices Inc.	RS422, RS485	1/1	250 kbps	3V ~ 5.5V	0°C ~ 70°C	150 mV	14-SOIC	Active	ROHS3
LTC2864CS-2#TRPBF	Analog Devices Inc.	RS422, RS485	1/1	250 kbps	3V ~ 5.5V	0°C ~ 70°C	150 mV	14-SOIC	Active	ROHS3
LTC2864HS-1#PBF	Analog Devices Inc.	RS422, RS485	1/1	20 Mbps	3V ~ 5.5V	-40°C ~ 125°C	150 mV	14-SOIC	Active	ROHS3
LTC2864HS-1#TRPBF	Analog Devices Inc.	RS422, RS485	1/1	20 Mbps	3V ~ 5.5V	-40°C ~ 125°C	150 mV	14-SOIC	Active	ROHS3

Engineering Selection Recommendations

All identified substitute parts maintain ROHS3 compliance and REACH unaffected status, meeting regulatory requirements equivalent to the ISL8491IBZ.

For applications requiring extended temperature range (-40°C to 125°C): LT1791AHS#PBF and LTC2864HS series (LTC2864HS-1#PBF, LTC2864HS-1#TRPBF) provide the widest operating temperature envelope. The LTC2864HS-1 variants additionally support higher data rates (20 Mbps) and lower supply voltage floor (3V).

For applications with standard industrial temperature range (-40°C to 85°C): LT1791AIS#PBF and LT1791AIS#TRPBF offer active product status with long-term availability. The tape and reel variant (LT1791AIS#TRPBF) is suitable for high-volume production environments.

For applications requiring higher data rate capability (20 Mbps): LTC2864CS-1 and LTC2864HS-1 series support data rates up to 20 Mbps, exceeding the ISL8491IBZ specification. These parts operate across 3V to 5.5V supply range, providing broader voltage compatibility.

For cost-optimized applications with lower data rate requirements (250 kbps): LTC2864CS-2 series and LT1791 variants provide functional equivalence at reduced complexity. The LTC2864CS-2#TRPBF variant offers tape and reel packaging for automated assembly.

All substitute parts are available in active product status, ensuring long-term supply chain stability compared to the obsolete ISL8491IBZ.

Frequently Asked Questions (FAQ)

Q: Can LT1791ACS#PBF directly replace ISL8491IBZ in existing designs?

A: LT1791ACS#PBF meets the core substitution criteria (RS422/RS485 full-duplex, 1/1 configuration, 14-SOIC package, ROHS3 compliance). However, the operating temperature range is limited to 0°C to 70°C, which is narrower than the ISL8491IBZ specification of -40°C to 85°C. This part is suitable only for applications operating within the 0°C to 70°C window.

Q: What is the difference between LT1791AIS#PBF and LT1791AIS#TRPBF?

A: Both parts are electrically identical LT1791AIS devices. The primary difference is packaging format: LT1791AIS#PBF is supplied in tube packaging, while LT1791AIS#TRPBF is supplied in tape and reel format. Tape and reel packaging is optimized for automated pick-and-place assembly in high-volume production.

Q: Why do LTC2864 parts specify a lower supply voltage floor (3V) compared to ISL8491IBZ (4.5V)?

A: The LTC2864 series is designed to operate across a wider supply voltage range (3V to 5.5V). This extended lower voltage capability does not affect compatibility with 4.5V to 5.5V systems; the part functions correctly within the ISL8491IBZ supply range and additionally supports lower voltage applications.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All identified substitute parts carry ROHS3 compliance certification and REACH unaffected status, matching the regulatory compliance profile of the ISL8491IBZ.

Q: Which substitute part offers the best long-term availability?

A: All substitute parts listed carry active product status from Analog Devices Inc., ensuring ongoing manufacturing and supply chain support. The LT1791 and LTC2864 base product families are established industry standards with multi-year availability commitments.

Q: Can I use LTC2864HS-1#PBF in applications requiring -40°C to 85°C operation?

A: Yes. LTC2864HS-1#PBF supports -40°C to 125°C operating temperature range, which encompasses the -40°C to 85°C requirement. This part provides additional temperature margin for demanding industrial environments.

Q: What is the significance of receiver hysteresis differences between ISL8491IBZ (70mV) and substitute parts (20mV or 150mV)?

A: Receiver hysteresis affects noise immunity and switching threshold characteristics. The ISL8491IBZ specifies 70mV hysteresis. Substitute parts with different hysteresis values (LT1791 at 20mV, LTC2864 at 150mV) maintain RS422/RS485 protocol compliance but exhibit different noise rejection characteristics. System-level signal integrity analysis is required to confirm compatibility in noise-sensitive applications.

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