SPX385AS-L-1-2/TR Equivalent & Substitute Parts

Part Overview

The SPX385AS-L-1-2/TR is a shunt voltage reference IC manufactured by MaxLinear, Inc., designed for precision power management applications. This fixed 1.235V reference device delivers 20 mA output current with ±1% tolerance and operates across the industrial temperature range of -40°C to 85°C. The part is housed in an 8-SOIC surface mount package with MSL 1 (Unlimited) moisture sensitivity rating.

The SPX385AS-L-1-2/TR is classified as Obsolete. Identifying functionally equivalent substitute parts is necessary to maintain design continuity, ensure supply chain reliability, and support ongoing production requirements for legacy systems.

Key Parameters

Parameter	Value
Reference Type	Shunt
Output Type	Fixed
Voltage - Output (Min/Fixed)	1.235V
Current - Output	20 mA
Tolerance	±1%
Temperature Coefficient	50ppm/°C
Noise - 10Hz to 10kHz	60µVrms
Current - Cathode	10 µA
Operating Temperature	-40°C ~ 85°C (TA)
Mounting Type	Surface Mount
Package / Case	8-SOIC (0.154", 3.90mm Width)
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution eligibility for the SPX385AS-L-1-2/TR is determined by strict alignment with the following core electrical and mechanical parameters:

Reference Type & Output Type: Must be Shunt reference with Fixed output
Output Voltage: Must be 1.235V (fixed)
Output Current: Must be 20 mA
Tolerance: Must be ±1%
Noise Specification: Must be 60µVrms (10Hz to 10kHz)
Cathode Current: Must be 10 µA or 20 µA (minor variation acceptable)
Operating Temperature Range: Must support -40°C to 85°C
Package: Must be 8-SOIC (0.154", 3.90mm Width)
Mounting Type: Must be Surface Mount

All substitute parts listed below meet these core requirements. Variations in Temperature Coefficient (20ppm/°C to 150ppm/°C) and Product Status do not disqualify substitution, as these parameters remain within acceptable engineering tolerances for shunt reference applications.

Parameter Comparison

Part Number	Manufacturer	Output Voltage	Output Current	Tolerance	Temp Coeff	Cathode Current	Operating Temp	Package	Product Status
SPX385AS-L-1-2/TR	MaxLinear, Inc.	1.235V	20 mA	±1%	50ppm/°C	10 µA	-40°C ~ 85°C	8-SOIC	Obsolete
LM285DR-1-2	Texas Instruments	1.235V	20 mA	±1%	20ppm/°C	10 µA	-40°C ~ 85°C	8-SOIC	Last Time Buy
LM285BXM-1.2/NOPB	National Semiconductor	1.235V	20 mA	±1%	30ppm/°C	10 µA	-40°C ~ 85°C	8-SOIC	Active
LM285BXMX-1.2/NOPB	Texas Instruments	1.235V	20 mA	±1%	30ppm/°C	10 µA	-40°C ~ 85°C	8-SOIC	Active
LM285BYM-1.2/NOPB	Texas Instruments	1.235V	20 mA	±1%	50ppm/°C	10 µA	-40°C ~ 85°C	8-SOIC	Active
LM285D-1-2	Texas Instruments	1.235V	20 mA	±1%	20ppm/°C	10 µA	-40°C ~ 85°C	8-SOIC	Last Time Buy
LM285D-1.2G	onsemi	1.235V	20 mA	±1%	80ppm/°C	20 µA	-40°C ~ 85°C	8-SOIC	Active
LM285D-1.2R2G	onsemi	1.235V	20 mA	±1%	80ppm/°C	20 µA	-40°C ~ 85°C	8-SOIC	Active
LM285DG4-1-2	Texas Instruments	1.235V	20 mA	±1%	20ppm/°C	10 µA	-40°C ~ 85°C	8-SOIC	Obsolete
LM285DRE4-1-2	Texas Instruments	1.235V	20 mA	±1%	20ppm/°C	10 µA	-40°C ~ 85°C	8-SOIC	Obsolete
LM285M-1.2/NOPB	Texas Instruments	1.235V	20 mA	±1%	150ppm/°C	10 µA	-40°C ~ 85°C	8-SOIC	Active

Engineering Selection Recommendations

Primary Recommendation: LM285BXMX-1.2/NOPB (Texas Instruments)

This part is the optimal substitute for the SPX385AS-L-1-2/TR. It maintains identical electrical specifications (1.235V, 20 mA, ±1%, 10 µA cathode current) and is classified as Active with full RoHS3 compliance and REACH Unaffected status. The 30ppm/°C temperature coefficient provides superior stability compared to the original 50ppm/°C specification. Packaging is Tape & Reel (TR), supporting high-volume production environments. Inventory availability is 3,600 units.

Secondary Recommendation: LM285BXM-1.2/NOPB (National Semiconductor)

This Active part offers identical electrical performance with 30ppm/°C temperature coefficient. It is the manufacturer-recommended substitute and provides the most direct functional equivalence. Inventory availability is 1,495 units. Packaging is Bulk.

Alternative Recommendation: LM285D-1.2R2G (onsemi)

This Active part maintains core specifications with 80ppm/°C temperature coefficient and 20 µA cathode current (versus 10 µA in the original). The higher cathode current represents a minor operational difference but remains within acceptable engineering tolerances for shunt reference applications. Tape & Reel packaging supports production requirements. Inventory availability is 21,068 units, the highest among all substitutes.

Consideration: LM285DR-1-2 (Texas Instruments)

This Last Time Buy part offers superior temperature coefficient performance (20ppm/°C) with identical electrical specifications. It is suitable for applications requiring enhanced thermal stability. Inventory availability is 35,300 units. Cut Tape & Digi-Reel packaging is available.

All recommended substitutes are housed in 8-SOIC packages with MSL 1 (Unlimited) ratings, ensuring direct mechanical and thermal compatibility with the original design.

Frequently Asked Questions (FAQ)

Q: Can LM285D-1.2R2G be used as a direct replacement for SPX385AS-L-1-2/TR?

A: Yes. LM285D-1.2R2G meets all core substitution criteria: 1.235V fixed output, 20 mA current, ±1% tolerance, 60µVrms noise, and 8-SOIC package. The cathode current is 20 µA (versus 10 µA in the original), which is a minor variation that does not prevent substitution. The 80ppm/°C temperature coefficient is higher than the original 50ppm/°C but remains acceptable for shunt reference applications.

Q: What is the difference between Tape & Reel and Bulk packaging?

A: Tape & Reel (TR) packaging is used for automated assembly processes and high-volume production. Bulk packaging is used for manual assembly or lower-volume applications. Both packaging formats contain identical die and electrical specifications. Selection depends on manufacturing process requirements, not electrical performance.

Q: Why do some substitutes have different temperature coefficients?

A: Temperature coefficient variation (20ppm/°C to 150ppm/°C) reflects different manufacturing processes and die designs across manufacturers. All listed substitutes remain within acceptable tolerances for shunt reference applications. Lower temperature coefficients (20ppm/°C) provide enhanced thermal stability; higher coefficients (150ppm/°C) are acceptable for less thermally sensitive applications.

Q: Are all substitute parts RoHS3 compliant?

A: Most substitute parts are RoHS3 compliant. LM285BXM-1.2/NOPB (National Semiconductor) does not specify RoHS status in the provided data. All other Active and Last Time Buy parts are confirmed RoHS3 compliant. Verify RoHS compliance with the specific manufacturer if required for your application.

Q: What is the significance of "Last Time Buy" and "Obsolete" product status?

A: Last Time Buy indicates the manufacturer will no longer accept new orders after a specified date but existing inventory remains available. Obsolete indicates production has ended and no new inventory will be manufactured. For the SPX385AS-L-1-2/TR (Obsolete), substitution with Active parts (LM285BXMX-1.2/NOPB, LM285BXM-1.2/NOPB, LM285BYM-1.2/NOPB, LM285D-1.2G, LM285D-1.2R2G, LM285M-1.2/NOPB) ensures long-term supply chain continuity.

Q: Can the SPX385AS-L-1-2/TR be used interchangeably with LM285M-1.2/NOPB?

A: Electrical substitution is possible. Both parts deliver 1.235V, 20 mA, ±1% tolerance, and operate across -40°C to 85°C in 8-SOIC packages. However, LM285M-1.2/NOPB has a 150ppm/°C temperature coefficient, significantly higher than the original 50ppm/°C. This part is suitable only for applications where thermal stability is not critical.

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