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LM385PSRE4-1-2 Equivalent & Substitute Parts
Part Overview
The LM385PSRE4-1-2 is a shunt voltage reference IC manufactured by Texas Instruments, designed to provide a fixed 1.235V output with ±2% tolerance. This component operates as a precision voltage reference in power management applications, delivering 20 mA output current with low noise characteristics (60µVrms across 10Hz to 10kHz bandwidth). The part is classified as obsolete, necessitating identification of active equivalent alternatives that maintain electrical and mechanical compatibility for ongoing system support and new designs.
Substiute Parts
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) |
| Mounting Type | Surface Mount |
| Package / Case | 8-SOIC (0.209", 5.30mm Width) |
| RoHS Status | ROHS3 Compliant |
| Moisture Sensitivity Level (MSL) | 1 (Unlimited) |
Substitute Part Grouping Explanation
Substitution of the LM385PSRE4-1-2 is determined by strict equivalence across the following electrical and mechanical parameters:
Critical Matching Parameters:
- Output voltage: 1.235V fixed
- Output current capability: 20 mA
- Reference type: Shunt topology
- Mounting type: Surface Mount
- Package type: 8-SOIC form factor
- Noise specification: 60µVrms (10Hz to 10kHz)
- Cathode current: 15 µA or lower
Tolerance Consideration: The main part specifies ±2% tolerance. Substitute parts with ±1% tolerance (tighter specification) are electrically compatible and provide improved accuracy. Parts with looser tolerance specifications are not suitable substitutes.
Temperature Range Consideration: The main part operates 0°C ~ 70°C. Substitute parts with extended temperature ranges (-40°C ~ 85°C) are compatible and provide broader operational capability. Parts with narrower temperature ranges are not suitable substitutes.
Package Dimension Variation: The main part uses 8-SOIC with 5.30mm width. Substitute parts using 8-SOIC with 3.90mm width are mechanically compatible for PCB layout purposes, as both conform to 8-SOIC pinout standards.
Parameter Comparison
| Part Number | Manufacturer | Status | Voltage Output | Current Output | Tolerance | Temp Coeff | Cathode Current | Operating Temp | Package | Inventory |
|---|---|---|---|---|---|---|---|---|---|---|
| LM385PSRE4-1-2 | Texas Instruments | Obsolete | 1.235V | 20 mA | ±2% | 20ppm/°C | 15 µA | 0°C ~ 70°C | 8-SOIC (5.30mm) | 1104 Pcs |
| LM285BXM-1.2/NOPB | National Semiconductor | Active | 1.235V | 20 mA | ±1% | 30ppm/°C | 10 µA | -40°C ~ 85°C | 8-SOIC (3.90mm) | 1495 Pcs |
| LM285BXMX-1.2/NOPB | Texas Instruments | Active | 1.235V | 20 mA | ±1% | 30ppm/°C | 10 µA | -40°C ~ 85°C | 8-SOIC (3.90mm) | 3600 Pcs |
| LM285BYM-1.2/NOPB | Texas Instruments | Active | 1.235V | 20 mA | ±1% | 50ppm/°C | 10 µA | -40°C ~ 85°C | 8-SOIC (3.90mm) | 3800 Pcs |
| LM285BYMX-1.2/NOPB | Texas Instruments | Active | 1.235V | 20 mA | ±1% | 50ppm/°C | 10 µA | -40°C ~ 85°C | 8-SOIC (3.90mm) | 5200 Pcs |
| LM285M-1.2/NOPB | Texas Instruments | Active | 1.235V | 20 mA | ±1% | 150ppm/°C | 10 µA | -40°C ~ 85°C | 8-SOIC (3.90mm) | 1305 Pcs |
| LM285MX-1.2/NOPB | Texas Instruments | Active | 1.235V | 20 mA | ±1% | 150ppm/°C | 10 µA | -40°C ~ 85°C | 8-SOIC (3.90mm) | 2600 Pcs |
| LM385BXM-1.2/NOPB | National Semiconductor | Active | 1.235V | 20 mA | ±1% | 30ppm/°C | 15 µA | 0°C ~ 70°C | 8-SOIC (3.90mm) | 2583 Pcs |
| LM385BXMX-1.2/NOPB | National Semiconductor | Active | 1.235V | 20 mA | ±1% | 30ppm/°C | 15 µA | 0°C ~ 70°C | 8-SOIC (3.90mm) | 5917 Pcs |
| LM385BYM-1.2/NOPB | Texas Instruments | Active | 1.235V | 20 mA | ±1% | 50ppm/°C | 15 µA | 0°C ~ 70°C | 8-SOIC (3.90mm) | 9302 Pcs |
| LM385BYMX-1.2/NOPB | Texas Instruments | Active | 1.235V | 20 mA | ±1% | 50ppm/°C | 15 µA | 0°C ~ 70°C | 8-SOIC (3.90mm) | 3700 Pcs |
Engineering Selection Recommendations
All listed substitute parts maintain electrical equivalence to the LM385PSRE4-1-2 across critical parameters: fixed 1.235V output, 20 mA output current, shunt reference topology, and 8-SOIC surface mount packaging. All substitute parts are classified as Active products, ensuring long-term availability and manufacturing support.
For applications requiring temperature range compatibility with the original specification (0°C ~ 70°C): Select LM385BXM-1.2/NOPB, LM385BXMX-1.2/NOPB, LM385BYM-1.2/NOPB, or LM385BYMX-1.2/NOPB. These parts maintain the original operating temperature range while providing ±1% tolerance improvement and ROHS3 compliance.
For applications permitting extended temperature operation (-40°C ~ 85°C): Select LM285BXM-1.2/NOPB, LM285BXMX-1.2/NOPB, LM285BYM-1.2/NOPB, LM285BYMX-1.2/NOPB, LM285M-1.2/NOPB, or LM285MX-1.2/NOPB. These parts provide broader operational capability with ±1% tolerance and ROHS3 compliance.
For high-volume procurement: LM385BYMX-1.2/NOPB (3700 Pcs), LM385BXMX-1.2/NOPB (5917 Pcs), and LM285BYMX-1.2/NOPB (5200 Pcs) offer substantial inventory availability in Tape & Reel packaging format.
All substitute parts carry ROHS3 compliance and MSL 1 (Unlimited) moisture sensitivity rating, matching the original part's environmental specifications.
Frequently Asked Questions (FAQ)
Q: Can LM285 series parts directly replace LM385 series parts? A: Yes. Both LM285 and LM385 series deliver identical electrical output (1.235V fixed, 20 mA, ±1% tolerance) and share 8-SOIC pinout compatibility. The primary difference is operating temperature range: LM285 extends to -40°C ~ 85°C, while LM385 operates 0°C ~ 70°C. Selection depends on application temperature requirements.
Q: What is the significance of the suffix codes (BXM, BYM, M, MX)? A: Suffix codes indicate packaging format and temperature coefficient specifications. BXM and BYM denote specific temperature coefficient grades (30ppm/°C and 50ppm/°C respectively). M and MX variants specify higher temperature coefficients (150ppm/°C). All variants maintain identical output voltage and current specifications.
Q: Does the 8-SOIC package dimension difference (5.30mm vs 3.90mm width) affect PCB compatibility? A: Both dimensions conform to 8-SOIC pinout standards and are mechanically compatible for PCB layout. The 3.90mm width represents a more compact form factor. Verify PCB footprint design accommodates the selected package width before assembly.
Q: Are all substitute parts ROHS3 compliant? A: Yes. All listed substitute parts carry ROHS3 compliance certification, matching the original LM385PSRE4-1-2 environmental specification.
Q: What packaging formats are available for substitute parts? A: Substitute parts are available in Bulk, Tube, Tape & Reel (TR), and Cut Tape (CT) & Digi-Reel® formats. Selection depends on procurement volume and assembly process requirements.
Q: Why is the original LM385PSRE4-1-2 classified as obsolete? A: Obsolescence reflects end-of-life status from the manufacturer. Active substitute parts with identical electrical specifications and improved tolerance (±1% vs ±2%) are available for design continuity and new production.
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