ISO35TDW RS422/RS485 Digital Isolator Equivalent & Substitute Parts

Part Overview

The ISO35TDW is a RS422/RS485 digital isolator manufactured by Texas Instruments, featuring 2500Vrms isolation voltage, 3 channels, and 1Mbps data rate in a 16-SOIC surface mount package. This device is currently in Last Time Buy status, indicating end-of-life production. Identifying equivalent and substitute parts is necessary to ensure design continuity and maintain supply chain reliability for applications requiring RS422/RS485 isolation functionality.

Substiute Parts

ISO35TDW

Texas InstrumentsIn Stock: 1234ISO35TDW Datasheet

Current PartRFQ

ISO35TDWR

Texas InstrumentsIn Stock: 50246ISO35TDWR Datasheet

MFR RecommendedRFQ

MAX14945EWE+

Analog Devices Inc./Maxim IntegratedIn Stock: 1183MAX14945EWE+ Datasheet

MFR RecommendedRFQ

MAX14945EWE+T

Analog Devices Inc./Maxim IntegratedIn Stock: 1107MAX14945EWE+T Datasheet

MFR RecommendedRFQ

MAX14949EWE+

Analog Devices Inc./Maxim IntegratedIn Stock: 1268MAX14949EWE+ Datasheet

MFR RecommendedRFQ

MAX14949EWE+T

Analog Devices Inc./Maxim IntegratedIn Stock: 3442MAX14949EWE+T Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the ISO35TDW is determined by the following critical parameters:

• Package Type: All substitutes must use 16-SOIC (0.295", 7.50mm Width) surface mount package for PCB compatibility
• Channel Configuration: 3 channels with 2/1 input/output distribution required
• Isolation Technology: Capacitive coupling technology maintained across all substitutes
• Interface Type: RS422/RS485 digital isolator functionality
• Operating Temperature Range: -40°C ~ 85°C minimum requirement
• RoHS Compliance: ROHS3 compliant status required

Substitutes are grouped into two categories based on isolation voltage and data rate capabilities:

Category 1 - Direct Packaging Equivalent: ISO35TDWR (Texas Instruments) - identical electrical specifications with alternative packaging (Cut Tape & Digi-Reel)

Category 2 - Enhanced Isolation Voltage: MAX14945EWE+, MAX14945EWE+T, MAX14949EWE+, MAX14949EWE+T (Analog Devices Inc./Maxim Integrated) - higher isolation voltage ratings with reduced data rate, suitable for applications requiring greater isolation margins

Parameter Comparison

Engineering Selection Recommendations

For Direct Replacement (No Design Changes Required):

ISO35TDWR is the primary substitute, offering identical electrical and functional specifications to the ISO35TDW. Both devices maintain 2500Vrms isolation voltage, 1Mbps data rate, and 3-channel configuration. The difference is packaging format: ISO35TDWR is supplied in Cut Tape & Digi-Reel format versus Tube packaging for the original part. This substitute is recommended for high-volume production requiring continuous supply and is currently in Active product status with significantly higher inventory availability (50,200 pcs).

For Enhanced Isolation Requirements:

MAX14945EWE+ and MAX14945EWE+T provide 2750Vrms isolation voltage with improved CMTI performance (35kV/µs typical) compared to the ISO35TDW (25kV/µs). These parts operate at 500kbps data rate, which is half the ISO35TDW specification. Selection is appropriate for applications where isolation margin enhancement is prioritized over maximum data rate. Both variants are in Active product status with ROHS3 compliance and MSL 1 rating (unlimited shelf life).

For Maximum Isolation Voltage:

MAX14949EWE+ and MAX14949EWE+T deliver 5000Vrms isolation voltage with 35kV/µs CMTI performance. These parts also operate at 500kbps data rate. Selection is appropriate for high-voltage isolation applications where the reduced data rate is acceptable. Both variants are in Active product status with ROHS3 compliance and MSL 1 rating. MAX14949EWE+T has the highest inventory availability (3,400 pcs).

All substitute parts maintain ROHS3 compliance, -40°C ~ 85°C operating temperature range, and 16-SOIC package compatibility required for PCB-level substitution.

Frequently Asked Questions (FAQ)

Q: Can ISO35TDWR be used as a direct drop-in replacement for ISO35TDW?

A: Yes. ISO35TDWR is electrically and functionally identical to ISO35TDW. The only difference is packaging format (Cut Tape & Digi-Reel versus Tube). Both maintain 2500Vrms isolation, 1Mbps data rate, 3 channels, and 16-SOIC package. No circuit design changes are required.

Q: What is the primary difference between ISO35TDWR and the MAX14945/MAX14949 series?

A: ISO35TDWR maintains the original 1Mbps data rate specification. MAX14945 and MAX14949 devices operate at 500kbps data rate. Additionally, MAX14945 provides 2750Vrms isolation and MAX14949 provides 5000Vrms isolation, both exceeding the ISO35TDW specification of 2500Vrms. These higher isolation ratings are suitable for applications requiring greater voltage isolation margins.

Q: Are all substitute parts compatible with the same PCB footprint?

A: Yes. All substitute parts use the 16-SOIC (0.295", 7.50mm Width) package, ensuring identical PCB footprint compatibility with the ISO35TDW. No PCB layout modifications are required for substitution.

Q: What is the impact of reduced data rate when using MAX14945 or MAX14949 substitutes?

A: MAX14945 and MAX14949 devices operate at 500kbps maximum data rate compared to ISO35TDW at 1Mbps. This reduction is relevant only for applications requiring data rates exceeding 500kbps. For applications operating at or below 500kbps, this parameter difference has no functional impact.

Q: Which substitute offers the best supply availability?

A: ISO35TDWR offers the highest inventory availability at 50,200 pcs, making it the optimal choice for high-volume production requirements. MAX14949EWE+T provides the second-highest availability at 3,400 pcs among the Analog Devices alternatives.

Q: Are all substitutes RoHS3 compliant?

A: Yes. All substitute parts listed (ISO35TDWR, MAX14945EWE+, MAX14945EWE+T, MAX14949EWE+, MAX14949EWE+T) are ROHS3 compliant, meeting environmental and regulatory requirements equivalent to the original ISO35TDW.

Q: What is the difference between MAX14945EWE+ and MAX14945EWE+T?

A: Both parts are electrically identical. The difference is packaging format: MAX14945EWE+ is supplied in Tube packaging, while MAX14945EWE+T is supplied in Tape & Reel format. Selection depends on production volume and handling requirements.

Q: Can MAX14949 be used in applications designed for ISO35TDW?

A: MAX14949 can be used as a substitute provided the application data rate requirement does not exceed 500kbps. The higher 5000Vrms isolation voltage is a superset capability and does not create compatibility issues. The 16-SOIC package ensures footprint compatibility.