LM385DG4-1-2 Equivalent & Substitute Parts

Part Overview

The LM385DG4-1-2 is a shunt voltage reference IC manufactured by Texas Instruments, designed for precision voltage reference applications requiring a fixed 1.235V output. This component operates as a fixed output type shunt reference with ±2% tolerance and is packaged in an 8-SOIC surface mount configuration. The part is classified as obsolete, necessitating identification of active equivalent alternatives that maintain electrical and mechanical compatibility for ongoing design support and production requirements.

Key Parameters

Parameter	Value
Reference Type	Shunt
Output Type	Fixed
Voltage - Output (Min/Fixed)	1.235V
Current - Output	20 mA
Tolerance	±2%
Noise - 10Hz to 10kHz	60µVrms
Current - Cathode	15 µA
Operating Temperature	0°C ~ 70°C (TA)
Package / Case	8-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution of the LM385DG4-1-2 is determined by strict adherence to the following electrical and mechanical parameters:

Critical Matching Parameters:

Reference Type: Shunt
Output Type: Fixed
Voltage - Output: 1.235V
Current - Output: 20 mA
Package / Case: 8-SOIC (0.154", 3.90mm Width)
Mounting Type: Surface Mount

Allowable Variation Parameters:

Tolerance: ±2% or better (±1% acceptable)
Temperature Coefficient: May vary (20ppm/°C to 150ppm/°C)
Current - Cathode: 10 µA to 15 µA acceptable
Operating Temperature: Extended range (-40°C ~ 85°C) acceptable for 0°C ~ 70°C requirement
Product Status: Active preferred over obsolete

Substitute parts must maintain identical output voltage, current rating, and package configuration. Improved tolerance specifications and extended temperature ranges represent acceptable enhancements. Packaging format variations (Tube, Bulk, Tape & Reel) are interchangeable based on procurement requirements.

Parameter Comparison

Part Number	Manufacturer	Voltage Output	Tolerance	Temp Coeff	Cathode Current	Operating Temp	Product Status	Packaging
LM385DG4-1-2	Texas Instruments	1.235V	±2%	20ppm/°C	15 µA	0°C ~ 70°C	Obsolete	Tube
LM285BXM-1.2/NOPB	National Semiconductor	1.235V	±1%	30ppm/°C	10 µA	-40°C ~ 85°C	Active	Bulk
LM285BXMX-1.2/NOPB	Texas Instruments	1.235V	±1%	30ppm/°C	10 µA	-40°C ~ 85°C	Active	Tape & Reel (TR)
LM285BYM-1.2/NOPB	Texas Instruments	1.235V	±1%	50ppm/°C	10 µA	-40°C ~ 85°C	Active	Tube
LM285BYMX-1.2/NOPB	Texas Instruments	1.235V	±1%	50ppm/°C	10 µA	-40°C ~ 85°C	Active	Tape & Reel (TR)
LM285M-1.2/NOPB	Texas Instruments	1.235V	±1%	150ppm/°C	10 µA	-40°C ~ 85°C	Active	Tube
LM285MX-1.2/NOPB	Texas Instruments	1.235V	±1%	150ppm/°C	10 µA	-40°C ~ 85°C	Active	Cut Tape (CT) & Digi-Reel®
LM385BM-1.2/NOPB	Texas Instruments	1.235V	±1%	150ppm/°C	15 µA	0°C ~ 70°C	Active	Tube
LM385BMX-1.2/NOPB	Texas Instruments	1.235V	±1%	150ppm/°C	15 µA	0°C ~ 70°C	Active	Tape & Reel (TR)
LM385BXM-1.2/NOPB	National Semiconductor	1.235V	±1%	30ppm/°C	15 µA	0°C ~ 70°C	Active	Bulk
LM385BXMX-1.2/NOPB	National Semiconductor	1.235V	±1%	30ppm/°C	15 µA	0°C ~ 70°C	Active	Bulk

Engineering Selection Recommendations

All listed substitute parts maintain the critical electrical specifications required for direct replacement: 1.235V fixed output, 20 mA output current capability, and 8-SOIC package configuration. Selection among active alternatives depends on specific application requirements and procurement constraints.

For applications requiring identical operating temperature range (0°C ~ 70°C) and cathode current (15 µA):

LM385BM-1.2/NOPB (Tube packaging)
LM385BMX-1.2/NOPB (Tape & Reel packaging)
LM385BXM-1.2/NOPB (Bulk packaging, National Semiconductor)
LM385BXMX-1.2/NOPB (Bulk packaging, National Semiconductor)

These parts offer improved ±1% tolerance compared to the original ±2% specification while maintaining identical temperature operating range and cathode current characteristics.

For applications permitting extended operating temperature range (-40°C ~ 85°C) and reduced cathode current (10 µA):

LM285BXM-1.2/NOPB (Bulk packaging, National Semiconductor)
LM285BXMX-1.2/NOPB (Tape & Reel packaging, Texas Instruments)
LM285BYM-1.2/NOPB (Tube packaging, Texas Instruments)
LM285BYMX-1.2/NOPB (Tape & Reel packaging, Texas Instruments)
LM285M-1.2/NOPB (Tube packaging, Texas Instruments)
LM285MX-1.2/NOPB (Cut Tape & Digi-Reel packaging, Texas Instruments)

All substitute parts carry ROHS3 compliance and REACH unaffected status where specified. Packaging format selection (Tube, Bulk, Tape & Reel, Cut Tape) is determined by procurement and assembly process requirements and does not affect electrical performance.

Frequently Asked Questions (FAQ)

Q: Can LM285 series parts directly replace the LM385DG4-1-2?

A: Yes, LM285 series parts are electrically compatible substitutes. They maintain the identical 1.235V output voltage, 20 mA output current, and 8-SOIC package. The LM285 series operates across an extended temperature range (-40°C ~ 85°C) compared to the original 0°C ~ 70°C specification, making them suitable for applications within the original temperature window. Cathode current is reduced to 10 µA versus the original 15 µA, which is acceptable for most applications.

Q: What is the difference between LM385 and LM285 base product numbers?

A: Both LM385 and LM285 are shunt voltage reference ICs with identical 1.235V output voltage and 20 mA output current specifications. The primary differences are temperature coefficient characteristics and operating temperature ranges. LM385 parts maintain the original 0°C ~ 70°C operating range, while LM285 parts extend to -40°C ~ 85°C. Selection depends on application temperature requirements.

Q: Does packaging format affect electrical performance?

A: No. Tube, Bulk, Tape & Reel, and Cut Tape & Digi-Reel packaging formats contain identical die and electrical specifications. Packaging selection is determined by procurement volume, assembly equipment compatibility, and supply chain requirements. All formats are electrically interchangeable.

Q: Why do some substitutes have ±1% tolerance instead of ±2%?

A: The substitute parts listed offer improved tolerance specifications compared to the original LM385DG4-1-2. A ±1% tolerance represents tighter output voltage accuracy and is a direct improvement over the original ±2% specification. This enhancement does not create compatibility issues; circuits designed for ±2% tolerance operate correctly with ±1% components.

Q: Are National Semiconductor and Texas Instruments parts interchangeable?

A: Yes. National Semiconductor LM385 and LM285 series parts are electrically and mechanically identical to Texas Instruments equivalents with matching part number suffixes. Both manufacturers produce parts with the same output voltage, current ratings, and package configuration. Selection between manufacturers is based on availability and procurement preference.

Q: What does the temperature coefficient specification mean for substitution?

A: Temperature coefficient (ppm/°C) indicates how much the output voltage changes per degree Celsius change in operating temperature. The original part specifies 20ppm/°C, while substitutes range from 30ppm/°C to 150ppm/°C. Higher temperature coefficients indicate greater voltage drift across temperature ranges. For applications operating within narrow temperature windows, this variation may be negligible. Applications requiring precise voltage stability across wide temperature ranges should prioritize lower temperature coefficient values.

Q: Can I use LM385BM-1.2/NOPB as a direct replacement?

A: Yes. LM385BM-1.2/NOPB maintains identical operating temperature range (0°C ~ 70°C) and cathode current (15 µA) as the original LM385DG4-1-2. It offers improved ±1% tolerance and is available in active product status. The only difference is packaging format (Tube versus the original Tube), making it a direct electrical and mechanical equivalent.

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