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Texas Instruments LM385BD-2-5
- Part No.:
- LM385BD-2-5
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM385BD-2-5.pdf
- Description:
- IC VREF SHUNT 1.5% 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:789
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Product details
Overview
LM385BD-2-5 from Texas Instruments is a micropower, two-terminal band-gap voltage reference delivering a precise 2.5 V output with ±1.5% initial tolerance, 1.5 Ω max reference impedance over full temperature range (0°C to 70°C), and operation from 20 μA to 20 mA cathode current - used in portable test instruments, battery-operated systems, and current-loop instrumentation.
For engineers reviewing the LM385BD-2-5 datasheet, LM385BD-2-5 pinout, LM385BD-2-5 application, or LM385BD-2-5 equivalent, key selection criteria include its shunt topology, SOIC-8 package compatibility, low 20 μA minimum operating current, ±20 ppm/°C tempco, and tolerance-critical use in precision analog metering and sensor signal conditioning.
Technical Context
The LM385BD-2-5 implements a floating shunt architecture with internal band-gap core and high-gain amplifier driving a shunt pass element, enabling stable 2.5 V regulation across capacitive loads without external compensation. Its design supports both positive and negative regulation configurations via cathode/anode terminal assignment.
Regulation requires sourcing ≥20 μA into the cathode pin while maintaining reverse bias; the anode serves as common ground reference. Internal trimming ensures tight initial voltage accuracy, and the device exhibits low broadband noise (120 µV, 10 Hz–10 kHz) and long-term stability (±20 ppm/khr).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage | 2.462 V to 2.538 V at 25°C - defines absolute accuracy window for precision analog circuits requiring ≤1.5% error budget. |
| Initial Tolerance | ±1.5% - achieved via on-chip laser trimming; enables direct replacement of older 3% references without recalibration. |
| Tempco (αVZ) | ±20 ppm/°C over 0°C to 70°C - ensures <0.35 mV drift across full operating range, critical for battery-powered metering. |
| Reference Impedance | ≤1.5 Ω over full temperature - maintains regulation stability under varying load currents and minimizes output voltage sag. |
| Operating Current Range | 20 μA to 20 mA - supports ultra-low-power sleep modes and higher-current precision DAC/ADC biasing in same design. |
| Long-Term Drift | ±20 ppm/khr at 100 μA - guarantees <50 ppm (0.0125 mV) shift over 2.5 years, suitable for field-deployed instrumentation. |
| Noise (10 Hz–10 kHz) | 120 µV RMS - low enough to avoid degrading 16-bit ADC performance when used as reference source. |
Pinout & Package
LM385BD-2-5 is housed in an 8-pin SOIC (D) package (4.90 mm × 3.90 mm, 1.75 mm max height), with pins 1–3 and 5–7 internally unconnected (NC). Only pins 4 (ANODE) and 8 (CATHODE) are functional terminals.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ANODE (Pin 4) | Common reference node | Typically connected to system ground; serves as return path for cathode current and establishes reference potential for shunt regulation. |
| CATHODE (Pin 8) | Shunt current/voltage input | Current must be sourced into this pin to enable regulation; voltage at this node is maintained at 2.5 V above ANODE potential. |
| Pins 1, 2, 3, 5, 6, 7 | No internal connection | Electrically isolated; no routing or termination required - simplifies PCB layout and avoids parasitic coupling paths. |
Key Features
| Feature | Design Value |
|---|---|
| Band-gap core with on-chip trimming | Delivers ±1.5% initial accuracy without external calibration - reduces BOM count and production test time. |
| Floating shunt topology | Enables use in high-side or low-side configurations, including negative supply rails and current-sense feedback loops. |
| Capacitive-load tolerance | Stable with >1 µF bypass capacitance on cathode - eliminates need for series isolation resistors in noisy environments. |
| Micropower operation | 20 μA minimum cathode current allows multi-year battery life in portable meters and remote sensors. |
| Low dynamic impedance | ≤1.5 Ω over 0°C–70°C ensures minimal load-induced voltage shift during transient events in precision analog stages. |
Applications
| Portable Meter References | Current-Loop Instrumentation |
|---|---|
Use Scenario: Handheld digital multimeters and panel-mounted voltage/current displays powered by single AA/AAA cells. IC Role / Device Role / Timing Role: Shunt voltage reference providing stable 2.5 V reference for ADC conversion and display scaling. Use Value: Enables ±0.1% measurement accuracy over battery discharge (0.9 V–1.5 V per cell) due to low 20 μA operating current and flat regulation curve. |
Use Scenario: 4–20 mA transmitter modules in industrial process control, where loop power is derived from remote 24 V supply. IC Role / Device Role / Timing Role: Precision shunt reference setting current-sense threshold and DAC reference in loop-powered transmitters. Use Value: Maintains loop accuracy within ±0.2% over temperature (0°C–70°C) and line voltage variation, meeting IEC 61000-4-5 surge immunity requirements. |
| Battery-Operated Systems | Thermocouple Cold-Junction Compensation |
Use Scenario: Wireless sensor nodes and IoT edge devices using coin-cell or Li-SOCl₂ batteries with 5–10 year lifetime targets. IC Role / Device Role / Timing Role: Low-quiescent reference for op-amp biasing, sensor excitation, and ADC reference in energy-harvesting subsystems. Use Value: Draws only 20 μA minimum, extending shelf-life-limited battery runtime by >30% compared to 100 μA references. |
Use Scenario: Industrial temperature measurement systems using Type K thermocouples requiring accurate 0°C cold-junction emulation. IC Role / Device Role / Timing Role: Fixed 2.5 V reference feeding precision resistor network that generates temperature-proportional voltage matching thermocouple output. Use Value: Achieves ±0.5°C cold-junction accuracy over 0°C–70°C due to matched tempco and low thermal EMF package construction. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar shunt voltage reference applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM385BLP-2-5 | Same electrical specs but TO-92 (3-pin) package; no NC pins; smaller footprint (4.3 mm × 4.3 mm) and lower thermal resistance (157°C/W). | Better suited for space-constrained, low-cost PCBs where SOIC reflow is impractical; limited to ≤1 W dissipation vs SOIC's 0.8 W. | Select for cost-sensitive, through-hole assembly or legacy board upgrades where SOIC footprint is unavailable. |
| LM385BPWR-2-5 | Identical specs in TSSOP-8 (3.0 mm × 4.4 mm); same pinout as SOIC but thinner profile (1.2 mm max) and wettable flanks for automated optical inspection. | Optimized for high-density SMT layouts and automated AOI; thermal resistance higher (168.3°C/W) than SOIC, limiting max power. | Select for compact, high-volume consumer electronics where board area and assembly yield outweigh thermal margin needs. |
Compared with LM385BLP-2-5 and LM385BPWR-2-5, the LM385BD-2-5 offers superior thermal performance (112°C/W) and mechanical robustness for industrial-grade PCBs, while retaining identical voltage accuracy, tempco, and micropower behavior - making it preferred for mission-critical analog signal chains.
Availability
LM385BD-2-5 is available at Aetrix Electronics and suitable for portable test instruments, battery-operated systems, and current-loop instrumentation requiring stable component supply across extended product lifecycles.
Supply support for LM385BD-2-5 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and connectivity technologies, with over 50 years of innovation in precision analog ICs.
The LM385B series was designed specifically for micropower, high-accuracy voltage referencing in portable and battery-constrained applications - emphasizing low drift, wide current range, and ease of use in shunt configurations.
FAQ
What is the minimum cathode current required for regulation in the LM385BD-2-5?
The LM385BD-2-5 requires a minimum cathode current (IZ(MIN)) of 20 μA across its full operating temperature range (0°C to 70°C) to maintain regulation. Below this threshold, the reference voltage drops out of specification. This value is guaranteed in the Electrical Characteristics table and verified across production lots.
Can the LM385BD-2-5 be used in a negative voltage reference configuration?
Yes, the LM385BD-2-5 supports negative reference configurations because it uses a floating shunt topology. When the anode is tied to a negative rail and current is sourced into the cathode, the cathode voltage remains 2.5 V above the anode - enabling generation of stable -2.5 V references in dual-supply systems.
What is the maximum power dissipation capability of the LM385BD-2-5 in SOIC-8 package?
The LM385BD-2-5 in SOIC-8 has a junction-to-ambient thermal resistance (RθJA) of 112°C/W. At 70°C ambient and 150°C max junction temperature, the maximum allowable power dissipation is 0.714 W. Derating is required above 25°C ambient per the thermal characteristics table.
Does the LM385BD-2-5 require an external capacitor for stability?
No, the LM385BD-2-5 features internal frequency compensation and is stable with any capacitive load up to at least 1 µF on the cathode node. A 0.1 µF ceramic bypass capacitor is optional and recommended only for high-noise environments to suppress RF pickup.
How does the LM385BD-2-5 differ from the standard LM385-2.5 in terms of voltage tolerance?
The LM385BD-2-5 belongs to the LM385B-2.5 family and carries ±1.5% initial voltage tolerance (2.462 V to 2.538 V), whereas the base LM385-2.5 has ±3% tolerance (2.425 V to 2.575 V). Both share identical tempco, noise, and impedance specs, but the 'B' grade enables tighter system-level accuracy without trimming.
LM385BD-2-5 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Series:
- -
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Reference Type:
- Shunt
- Output Type:
- Fixed
- Voltage - Output (Min/Fixed):
- 2.5V
- Voltage - Output (Max):
- -
- Current - Output:
- 20 mA
- Tolerance:
- ±1.5%
- Temperature Coefficient:
- 20ppm/°C Typical
- Noise - 0.1Hz to 10Hz:
- -
- Noise - 10Hz to 10kHz:
- 120µVrms
- Voltage - Input:
- -
- Current - Supply:
- -
- Current - Cathode:
- 20 µA
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
LM385BD-2-5 FAQ
1.How can I place an order for LM385BD-2-5 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM385BD-2-5 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LM385BD-2-5 reliable?
The price and inventory of LM385BD-2-5 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM385BD-2-5 is usually 5 days.
3.What payment methods are accepted for LM385BD-2-5?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM385BD-2-5 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM385BD-2-5?
LM385BD-2-5 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM385BD-2-5 order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LM385BD-2-5?
For technical support, including LM385BD-2-5 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM385BD-2-5 requirements.
6.How does Aetrix verify that LM385BD-2-5 is sourced from the original manufacturer or authorized distributors?
All LM385BD-2-5 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LM385BD-2-5 meets industry standards.
7.What is the process for return or replacement of LM385BD-2-5?
All LM385BD-2-5 units undergo pre-shipment inspection (PSI). If there is an issue with LM385BD-2-5, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LM385BD-2-5 part is unused and in its original packaging.
Return procedure for LM385BD-2-5:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM385BD-2-5 Tags
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TL431AIDBZR
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TL431BQDBZR
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LM4040CYM3-4.1-TR
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AZ431LBNTR-G1
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LM4041DIM3-ADJ/NOPB
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LM4040DIM3X-2.5/NOPB
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LM4040DIM3-2.5/NOPB
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AZ431LANTR-G1
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