LM285DRE4-1-2 Equivalent & Substitute Parts

Part Overview

The LM285DRE4-1-2 is a shunt voltage reference IC manufactured by Texas Instruments, delivering a fixed 1.235V output with ±1% tolerance. This component operates as a precision voltage reference in power management applications, featuring 20 mA output current capability and low noise characteristics (60µVrms across the 10Hz to 10kHz band). The part is classified as obsolete, necessitating identification of active equivalent alternatives that maintain electrical and mechanical compatibility for ongoing production and maintenance applications.

Key Parameters

Parameter	Value
Reference Type	Shunt
Output Type	Fixed
Voltage - Output (Min/Fixed)	1.235V
Current - Output	20 mA
Tolerance	±1%
Noise - 10Hz to 10kHz	60µVrms
Current - Cathode	10 µA
Operating Temperature	-40°C ~ 85°C (TA)
Package / Case	8-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the LM285DRE4-1-2 is determined by the following critical parameters:

Output Voltage: Must be 1.235V fixed
Output Current: Must be 20 mA
Reference Type: Must be Shunt
Package: Must be 8-SOIC (0.154", 3.90mm Width)
Mounting Type: Must be Surface Mount
Noise Specification: Must meet 60µVrms at 10Hz to 10kHz

Secondary parameters that may vary within acceptable ranges include temperature coefficient, cathode current, and operating temperature range. Packaging format (Tube, Tape & Reel, Bulk, Cut Tape) does not affect electrical compatibility but impacts procurement and assembly workflows. Parts with active product status are preferred over obsolete designations for long-term supply chain reliability.

Parameter Comparison

Part Number	Manufacturer	Status	Voltage Output	Current Output	Tolerance	Temp Coeff	Cathode Current	Operating Temp	Packaging
LM285DRE4-1-2	Texas Instruments	Obsolete	1.235V	20 mA	±1%	20ppm/°C	10 µA	-40°C ~ 85°C	Tape & Reel
LM285BXM-1.2/NOPB	National Semiconductor	Active	1.235V	20 mA	±1%	30ppm/°C	10 µA	-40°C ~ 85°C	Bulk
LM285BXMX-1.2/NOPB	Texas Instruments	Active	1.235V	20 mA	±1%	30ppm/°C	10 µA	-40°C ~ 85°C	Tape & Reel
LM285BYM-1.2/NOPB	Texas Instruments	Active	1.235V	20 mA	±1%	50ppm/°C	10 µA	-40°C ~ 85°C	Tube
LM285BYMX-1.2/NOPB	Texas Instruments	Active	1.235V	20 mA	±1%	50ppm/°C	10 µA	-40°C ~ 85°C	Tape & Reel
LM285M-1.2/NOPB	Texas Instruments	Active	1.235V	20 mA	±1%	150ppm/°C	10 µA	-40°C ~ 85°C	Tube
LM285MX-1.2/NOPB	Texas Instruments	Active	1.235V	20 mA	±1%	150ppm/°C	10 µA	-40°C ~ 85°C	Cut Tape & Digi-Reel
LM385BM-1.2/NOPB	Texas Instruments	Active	1.235V	20 mA	±1%	150ppm/°C	15 µA	0°C ~ 70°C	Tube
LM385BMX-1.2/NOPB	Texas Instruments	Active	1.235V	20 mA	±1%	150ppm/°C	15 µA	0°C ~ 70°C	Tape & Reel
LM385M-1.2/NOPB	Texas Instruments	Active	1.235V	20 mA	-2.43%, +2.02%	150ppm/°C	15 µA	0°C ~ 70°C	Tube
LM385MX-1.2/NOPB	Texas Instruments	Active	1.235V	20 mA	-2.43%, +2.02%	150ppm/°C	15 µA	0°C ~ 70°C	Tape & Reel

Engineering Selection Recommendations

Primary Substitutes (Highest Compatibility)

LM285BXMX-1.2/NOPB and LM285BYM-1.2/NOPB are the preferred direct replacements. Both maintain the original -40°C to 85°C operating temperature range, ±1% tolerance specification, and 10 µA cathode current. LM285BXMX-1.2/NOPB is available in Tape & Reel packaging matching the original format. Both parts carry active product status and ROHS3 compliance, ensuring long-term availability and regulatory alignment.

Secondary Substitutes (Extended Temperature Coefficient)

LM285M-1.2/NOPB and LM285MX-1.2/NOPB provide functional equivalence with identical electrical specifications except for temperature coefficient (150ppm/°C versus 20ppm/°C). These parts are suitable for applications where thermal stability is less critical. LM285MX-1.2/NOPB offers Tape & Reel packaging.

Limited Compatibility Substitutes

LM385BM-1.2/NOPB, LM385BMX-1.2/NOPB, LM385M-1.2/NOPB, and LM385MX-1.2/NOPB operate within a narrower temperature range (0°C to 70°C) and exhibit higher cathode current (15 µA). These parts are suitable only for applications operating within the restricted temperature band. LM385M-1.2/NOPB and LM385MX-1.2/NOPB feature asymmetrical tolerance (-2.43%, +2.02%), requiring circuit validation.

Packaging Considerations

For automated assembly workflows requiring Tape & Reel format, select LM285BXMX-1.2/NOPB, LM285BYM-1.2/NOPB, LM285BYMX-1.2/NOPB, LM285MX-1.2/NOPB, LM385BMX-1.2/NOPB, or LM385MX-1.2/NOPB. For manual or low-volume assembly, Tube packaging (LM285BYM-1.2/NOPB, LM285M-1.2/NOPB, LM385BM-1.2/NOPB, LM385M-1.2/NOPB) is acceptable. Bulk packaging (LM285BXM-1.2/NOPB) is suitable for high-volume procurement with internal reel management.

All substitute parts maintain ROHS3 compliance and EAR99 export classification consistent with the original part.

Frequently Asked Questions (FAQ)

Q: Can LM385 series parts directly replace LM285DRE4-1-2?

A: LM385BM-1.2/NOPB and LM385BMX-1.2/NOPB are electrically compatible but operate within a narrower temperature range (0°C to 70°C versus -40°C to 85°C) and exhibit higher cathode current (15 µA versus 10 µA). These differences require circuit validation before deployment in applications requiring the full -40°C to 85°C range or sensitive to cathode current variations.

Q: What is the significance of temperature coefficient differences?

A: Temperature coefficient (ppm/°C) indicates voltage drift per degree Celsius. The original part specifies 20ppm/°C, while most substitutes range from 30ppm/°C to 150ppm/°C. Lower coefficients provide superior thermal stability. Applications requiring minimal voltage variation across temperature extremes should prioritize LM285BXMX-1.2/NOPB (30ppm/°C) or LM285BYM-1.2/NOPB (50ppm/°C).

Q: Are packaging format differences significant for circuit design?

A: Packaging format (Tube, Tape & Reel, Bulk, Cut Tape) does not affect electrical performance or pin configuration. Selection depends on assembly methodology and procurement volume. Tape & Reel format is standard for automated pick-and-place assembly. Tube packaging suits manual assembly or low-volume production.

Q: Does the LM285BXM-1.2/NOPB (Bulk) differ electrically from Tape & Reel versions?

A: No. Bulk and Tape & Reel packaging contain identical die and electrical specifications. The difference is purely logistical—Bulk packaging requires internal reel management during assembly, while Tape & Reel is directly compatible with standard SMT equipment.

Q: Can parts with asymmetrical tolerance (-2.43%, +2.02%) be used in precision applications?

A: LM385M-1.2/NOPB and LM385MX-1.2/NOPB feature asymmetrical tolerance specifications. These parts are suitable only for applications where the asymmetrical tolerance band is acceptable. Circuits designed for ±1% symmetrical tolerance require validation before substitution.

Q: What is the impact of cathode current differences (10 µA versus 15 µA)?

A: Cathode current affects bias network design and power dissipation. Parts with 15 µA cathode current (LM385 series) require slightly higher bias resistor values. This difference is typically accommodated through standard circuit design practices but should be confirmed during circuit validation.

Q: Which substitute offers the best long-term supply chain reliability?

A: LM285BXMX-1.2/NOPB, LM285BYM-1.2/NOPB, and LM285BYMX-1.2/NOPB all carry active product status from Texas Instruments with substantial inventory levels (3600, 3800, and 5200 units respectively). These parts provide the highest confidence for sustained availability.

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