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DS485TM RS422/RS485 Half-Duplex Transceiver Equivalent & Substitute Parts
Part Overview
The DS485TM is a half-duplex RS422/RS485 transceiver manufactured by Texas Instruments in an 8-SOIC surface mount package. This part is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production support. The DS485TM operates within a 4.75V to 5.25V supply range with a 2.5 Mbps data rate and supports industrial temperature ranges from -40°C to 85°C. Identifying compatible substitutes ensures design continuity and supply chain flexibility.
Substiute Parts
Key Parameters
| Parameter | DS485TM Value |
|---|---|
| Manufacturer | Texas Instruments |
| Protocol | RS422, RS485 |
| Type | Transceiver Half-Duplex |
| Number of Drivers/Receivers | 1/1 |
| 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 | 8-SOIC (0.154", 3.90mm Width) |
| Product Status | Obsolete |
| RoHS Status | RoHS non-compliant |
Substitute Part Grouping Explanation
Substitution of the DS485TM is determined by strict alignment of the following electrical and mechanical parameters:
Critical Matching Parameters:
- Protocol: RS422/RS485 half-duplex operation
- Number of Drivers/Receivers: 1/1 configuration
- Package Type: 8-SOIC or equivalent 8-pin surface mount
- Voltage Supply Range: Minimum 4.75V to 5.25V compatibility
- Operating Temperature: Support for -40°C to 85°C range
- Mounting Type: Surface mount only
Acceptable Variation Parameters:
- Receiver Hysteresis: 30 mV to 70 mV (within functional tolerance)
- Data Rate: 2.5 Mbps or higher (backward compatible)
- RoHS Compliance: Modern substitutes are RoHS3 compliant; original is non-compliant
Substitute parts are grouped into two categories: direct manufacturer-recommended alternatives and functionally equivalent parts from alternative manufacturers. All listed substitutes maintain the same pinout compatibility and electrical interface characteristics required for drop-in replacement.
Parameter Comparison
| Part Number | Manufacturer | Protocol | Drivers/Receivers | Receiver Hysteresis | Data Rate | Supply Voltage | Operating Temp | Package | Product Status | RoHS Status |
|---|---|---|---|---|---|---|---|---|---|---|
| DS485TM | Texas Instruments | RS422, RS485 | 1/1 | 70 mV | 2.5 Mbps | 4.75V ~ 5.25V | -40°C ~ 85°C | 8-SOIC | Obsolete | Non-compliant |
| SN65HVD485ED | Texas Instruments | RS422, RS485 | 1/1 | 30 mV | 10 Mbps | 4.5V ~ 5.5V | -40°C ~ 85°C | 8-SOIC | Last Time Buy | ROHS3 Compliant |
| LTC485IS8#PBF | Analog Devices Inc. | RS422, RS485 | 1/1 | 70 mV | — | 4.75V ~ 5.25V | -40°C ~ 85°C | 8-SOIC | Active | ROHS3 Compliant |
| LTC485IS8#TRPBF | Analog Devices Inc. | RS422, RS485 | 1/1 | 70 mV | — | 4.75V ~ 5.25V | -40°C ~ 85°C | 8-SOIC | Active | ROHS3 Compliant |
| MAX481ESA+T | Analog Devices Inc./Maxim Integrated | RS422, RS485 | 1/1 | 70 mV | 2.5 Mbps | 4.75V ~ 5.25V | -40°C ~ 85°C | 8-SOIC | Active | ROHS3 Compliant |
| MAX485ESA+T | Analog Devices Inc./Maxim Integrated | RS422, RS485 | 1/1 | 70 mV | 2.5 Mbps | 4.75V ~ 5.25V | -40°C ~ 85°C | 8-SOIC | Active | ROHS3 Compliant |
| ST485BDR | STMicroelectronics | RS422, RS485 | 1/1 | 70 mV | 2.5 Mbps | 4.75V ~ 5.25V | -40°C ~ 85°C | 8-SOIC | Active | ROHS3 Compliant |
| ADM485ARZ | UMW | RS422, RS485 | 1/1 | 70 mV | 2.5 Mbps | 4.75V ~ 5.25V | 0°C ~ 70°C | 8-SOIC | Active | — |
| ADM485ARZ-REEL | Analog Devices Inc. | RS422, RS485 | 1/1 | 70 mV | 5 Mbps | 4.75V ~ 5.25V | -40°C ~ 85°C | 8-SOIC | Active | ROHS3 Compliant |
| ADM485EARZ-REEL7 | Analog Devices Inc. | RS422, RS485 | 1/1 | 70 mV | 2.5 Mbps | 4.75V ~ 5.25V | -40°C ~ 85°C | 8-SOIC | Active | ROHS3 Compliant |
| ADM485JRZ | Analog Devices Inc. | RS422, RS485 | 1/1 | 70 mV | 5 Mbps | 4.75V ~ 5.25V | 0°C ~ 70°C | 8-SOIC | Active | ROHS3 Compliant |
Engineering Selection Recommendations
Primary Recommendation: MAX485ESA+T or MAX481ESA+T
The MAX485ESA+T and MAX481ESA+T from Analog Devices Inc./Maxim Integrated are the preferred substitutes. Both maintain identical electrical specifications to the DS485TM (70 mV receiver hysteresis, 2.5 Mbps data rate, 4.75V to 5.25V supply, -40°C to 85°C operating range) while offering active product status and full RoHS3 compliance. These parts are widely available with high inventory levels and are suitable for new designs requiring modern compliance certifications.
Secondary Recommendation: ST485BDR
The ST485BDR from STMicroelectronics provides an alternative from a different manufacturer with identical electrical and thermal specifications. This part is active, RoHS3 compliant, and maintains full compatibility with the DS485TM pinout and functionality.
Alternative for Extended Data Rate: ADM485ARZ-REEL
For applications requiring higher data rate capability, the ADM485ARZ-REEL from Analog Devices Inc. supports 5 Mbps operation while maintaining all other DS485TM specifications. This part is active and RoHS3 compliant.
Temperature-Constrained Applications: ADM485ARZ or ADM485JRZ
The ADM485ARZ and ADM485JRZ variants operate within a 0°C to 70°C temperature range and are suitable only for applications that do not require the full -40°C to 85°C industrial range of the original DS485TM.
Not Recommended: SN65HVD485ED
While the SN65HVD485ED is a Texas Instruments product with Last Time Buy status, it features a reduced receiver hysteresis of 30 mV and an extended supply voltage range (4.5V to 5.5V). These differences may introduce compatibility issues in systems designed specifically for the DS485TM's 70 mV hysteresis specification.
Frequently Asked Questions (FAQ)
Q: Can I use MAX485ESA+T as a direct replacement for DS485TM?
A: Yes. The MAX485ESA+T maintains identical pinout, electrical specifications (70 mV receiver hysteresis, 2.5 Mbps data rate, 4.75V to 5.25V supply), and operating temperature range (-40°C to 85°C). It is a direct drop-in substitute with improved product status and RoHS3 compliance.
Q: What is the difference between LTC485IS8#PBF and LTC485IS8#TRPBF?
A: Both parts are electrically identical. The primary difference is packaging: LTC485IS8#PBF is supplied in Tube packaging, while LTC485IS8#TRPBF is supplied in Cut Tape (CT) & Digi-Reel format. Select based on your procurement and assembly requirements.
Q: Why does SN65HVD485ED have different receiver hysteresis?
A: The SN65HVD485ED is a higher-performance variant with 30 mV hysteresis compared to the DS485TM's 70 mV. This reduced hysteresis provides tighter noise margins but may not be compatible with systems calibrated for the original 70 mV specification. Use only if your application supports this parameter change.
Q: Are all substitute parts RoHS3 compliant?
A: Most substitutes are RoHS3 compliant. The ADM485ARZ (UMW variant) does not specify RoHS status in the provided data. For new designs, prioritize parts with explicit RoHS3 compliance certification.
Q: Can I use ADM485ARZ for industrial temperature applications?
A: No. The ADM485ARZ operates only within 0°C to 70°C, which does not cover the full -40°C to 85°C industrial range of the DS485TM. Use ADM485ARZ-REEL or ADM485EARZ-REEL7 for full temperature range support.
Q: What is the advantage of ADM485ARZ-REEL over MAX485ESA+T?
A: The ADM485ARZ-REEL supports a higher data rate of 5 Mbps compared to the MAX485ESA+T's 2.5 Mbps. Both maintain identical supply voltage and temperature ranges. Select ADM485ARZ-REEL if your application requires higher bandwidth; otherwise, MAX485ESA+T is the standard choice.
Q: Are there any supply voltage compatibility concerns?
A: The DS485TM requires 4.75V to 5.25V. Most substitutes maintain this range. The SN65HVD485ED extends to 4.5V to 5.5V, which is broader but may introduce compatibility issues if your system is calibrated for the narrower original range. Verify your power supply specifications before substitution.
Q: Can I mix different substitute parts in the same design?
A: Yes, provided all parts meet your application's electrical and thermal requirements. However, for consistency and supply chain simplification, standardizing on a single substitute part (such as MAX485ESA+T) is recommended for production designs.
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