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Texas Instruments LM385BDR-2-5
- Part No.:
- LM385BDR-2-5
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM385BDR-2-5.pdf
- Description:
- IC VREF SHUNT 1.5% 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:148
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Product details
Overview
LM385BDR-2-5 from Texas Instruments is a micropower, two-terminal band-gap voltage reference delivering a precise 2.5 V output with ±0.4% initial tolerance (2.462 V to 2.538 V), 1.5 Ω max reference impedance over full temperature range, and ±20 ppm/°C tempco across 0°C to 70°C. It operates from 20 μA to 20 mA cathode current and serves as a stable reference in portable test instruments and battery-operated analog signal chains.
For engineers reviewing the LM385BDR-2-5 datasheet, LM385BDR-2-5 pinout, LM385BDR-2-5 application, or LM385BDR-2-5 equivalent, this page delivers verified specifications, SOIC-8 package terminal mapping, real-world use cases in thermocouple compensation and current-loop instrumentation, and validated alternative parts for design continuity.
Technical Context
The LM385BDR-2-5 implements a floating shunt topology with internal band-gap core, high-gain amplifier, and shunt pass element - enabling stable 2.5 V regulation without requiring a ground-referenced input. Its fully compensated loop supports stable operation with any capacitive load, including optional 0.1-μF ceramic bypass on the cathode node.
Regulation initiates only when minimum cathode current (8–20 μA) is supplied; below this threshold, the device enters low-current dropout. The reference impedance remains ≤1 Ω at 25°C and ≤1.5 Ω across full operating temperature (0°C to 70°C), ensuring minimal voltage shift under dynamic load conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage | 2.5 V nominal, 2.462–2.538 V (±0.4%) at 20 μA–20 mA; enables precision ADC/DAC biasing and sensor excitation. |
| Initial Tolerance | ±0.4% (LM385B grade); tighter than standard LM385-2.5 (±1.5%), reducing calibration burden in portable meters. |
| Tempco | ±20 ppm/°C over 0°C to 70°C; ensures <±0.35 mV drift across industrial ambient range. |
| Reference Impedance | ≤1 Ω at 25°C, ≤1.5 Ω over full temperature; minimizes load-induced error in ratiometric systems. |
| Operating Current Range | 20 μA to 20 mA; supports ultra-low-power sleep modes and high-accuracy active measurement simultaneously. |
| Noise (10 Hz–10 kHz) | 120 μV broadband; suitable for 12-bit+ precision analog front-ends without external filtering. |
| Long-Term Stability | ±20 ppm/khr at 100 μA; predicts <±0.2% drift over 10-year field life in battery-powered equipment. |
Pinout & Package
LM385BDR-2-5 is housed in an 8-pin SOIC (D) package (4.90 mm × 3.90 mm body, 1.75 mm max height), RoHS-compliant, with moisture sensitivity level (MSL) 1 (260°C peak reflow).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ANODE (Pin 4) | Common terminal | Typically connected to system ground; forms return path for cathode current and defines reference potential. |
| CATHODE (Pin 8) | Shunt current/voltage input | Current-sink node where regulated 2.5 V appears relative to ANODE; connects to supply via series resistor or current source. |
| Pins 1, 2, 3, 5, 6, 7 | No internal connection | Electrically isolated; must remain unconnected or tied to ANODE only if required for mechanical stability - no functional role. |
Key Features
| Feature | Design Value |
|---|---|
| Floating shunt architecture | Enables both high-side and low-side regulation topologies - e.g., generating negative references or sensing current in grounded-load configurations. |
| Capacitive-load immunity | Internally compensated loop eliminates need for external phase compensation, simplifying layout in space-constrained portable designs. |
| Micropower operation | 20 μA minimum operating current extends battery life in devices like handheld multimeters where shelf-life matching is critical. |
| Low dynamic impedance | ≤1.5 Ω over full temperature ensures <±30 mV output shift even with 20 mA step-load transients - vital for stable feedback in LDOs. |
| Band-gap core with trimming | On-die laser trimming achieves ±0.4% initial accuracy without external calibration, reducing BOM count and test time. |
Applications
| Portable Test Instrumentation | Thermocouple Cold-Junction Compensation |
|---|---|
Use Scenario: Handheld digital multimeter measuring DC voltage with 12-bit SAR ADC. IC Role / Device Role / Timing Role: Provides stable 2.5 V reference for ADC internal conversion and display scaling circuitry. Use Value: ±0.4% initial tolerance and ±20 ppm/°C tempco ensure <±0.05% full-scale error across 0–40°C operating range without recalibration. |
Use Scenario: Industrial temperature transmitter using Type K thermocouple with cold-junction sensing. IC Role / Device Role / Timing Role: Supplies precise 2.5 V bias to op-amp-based ice-point compensation network. Use Value: Low 120 μV noise and <1.5 Ω impedance prevent thermal EMF errors and maintain <0.5°C measurement accuracy. |
| Battery-Operated Sensor Nodes | Current-Loop Transmitters (4–20 mA) |
Use Scenario: Wireless environmental sensor node powered by two AA cells (2.4–3.2 V range). IC Role / Device Role / Timing Role: Serves as ratiometric reference for bridge-sensor signal conditioning and microcontroller ADC. Use Value: 20 μA min operating current allows continuous reference operation during deep-sleep cycles, preserving measurement readiness. |
Use Scenario: Loop-powered 4–20 mA transmitter with HART modulation capability. IC Role / Device Role / Timing Role: Sets accurate 2.5 V reference for DAC-controlled current output stage and HART sine-wave generation. Use Value: ≤1.5 Ω impedance prevents loop-current modulation distortion; long-term stability avoids field recalibration every 6 months. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar shunt voltage reference applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM385DR-2-5 | ±1.5% initial tolerance (vs. ±0.4%); same SOIC-8 package, 0°C–70°C range, identical pinout. | Acceptable where calibration is performed post-assembly; not suitable for factory-trimmed zero-calibration systems. | Select when cost sensitivity outweighs absolute accuracy requirements and board layout reuse is prioritized. |
| REF3025AIDBZR | 10 ppm/°C tempco (vs. ±20 ppm/°C); 3.5 μA quiescent current; SOT-23-3 package; different pinout (VOUT, GND, VIN). | Requires PCB redesign; superior for ultra-low-power IoT nodes needing <10 ppm/°C drift but incompatible with existing SOIC footprints. | Choose for next-generation designs targeting >16-bit precision and sub-5 μA standby, accepting layout change. |
Compared with LM385DR-2-5, LM385BDR-2-5 delivers 3.75× tighter initial accuracy at identical footprint and cost bracket; versus REF3025AIDBZR, it trades lower power and better tempco for SOIC-8 compatibility and proven robustness in legacy industrial layouts.
Availability
LM385BDR-2-5 is available at Aetrix Electronics and suitable for portable test instrumentation, battery-operated sensor nodes, and current-loop transmitters requiring stable component supply with guaranteed long-term sourcing.
Supply support for LM385BDR-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 and embedded processing technologies, with over 50 years of innovation in precision analog ICs and power management solutions.
The LM385B series belongs to TI's micropower voltage reference product line, engineered specifically for battery-constrained, high-accuracy analog systems where low drift, low noise, and wide operating current range are mandatory.
FAQ
What is the minimum cathode current required for regulation in the LM385BDR-2-5?
The LM385BDR-2-5 requires a minimum cathode current (IZ(MIN)) of 8 μA to 20 μA across its operating temperature range (0°C to 70°C). Below this threshold, regulation fails and output voltage collapses. At 25°C, typical IZ(MIN) is 10 μA. This value is critical for sizing the series resistor or current source in battery-powered applications - undersizing causes reference dropout during low-power states.
Can the LM385BDR-2-5 be used in negative-voltage reference configurations?
Yes, the LM385BDR-2-5 supports floating shunt operation, allowing it to generate negative references when the ANODE is tied to a positive rail and CATHODE is connected to the system ground or a negative supply node. Its two-terminal architecture enables bidirectional current flow - essential for cold-junction compensation circuits and dual-supply op-amp biasing where conventional ground-referenced references fail.
How does the LM385BDR-2-5 compare to the LM385-2.5 in terms of accuracy and stability?
The LM385BDR-2-5 offers ±0.4% initial voltage tolerance (2.462–2.538 V), whereas the standard LM385-2.5 specifies ±1.5% (2.425–2.575 V). Both share identical ±20 ppm/°C tempco and 1.5 Ω max reference impedance, but the LM385BDR-2-5's tighter tolerance reduces system-level calibration overhead - especially valuable in portable meters and uncalibrated field instruments where factory trim is omitted.
Is a bypass capacitor required on the CATHODE pin of the LM385BDR-2-5?
A 0.1-μF ceramic bypass capacitor on the CATHODE pin is optional but recommended for noise-sensitive applications such as high-resolution ADC references or precision current sources. The LM385BDR-2-5's internally compensated loop remains stable without it, but the capacitor suppresses high-frequency supply noise and improves PSRR above 10 kHz - particularly beneficial in mixed-signal PCBs with switching regulators nearby.
What is the maximum cathode current rating for continuous operation of the LM385BDR-2-5?
The LM385BDR-2-5 supports up to 20 mA of continuous cathode current per its Recommended Operating Conditions. Absolute Maximum Ratings allow 30 mA transiently, but sustained operation above 20 mA risks exceeding the SOIC-8 package's thermal limits - especially at elevated ambient temperatures. For 20 mA loads, ensure adequate PCB copper area and airflow to maintain junction temperature below 150°C.
LM385BDR-2-5 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- 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
LM385BDR-2-5 FAQ
1.How can I place an order for LM385BDR-2-5 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM385BDR-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 LM385BDR-2-5 reliable?
The price and inventory of LM385BDR-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 LM385BDR-2-5 is usually 5 days.
3.What payment methods are accepted for LM385BDR-2-5?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM385BDR-2-5 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM385BDR-2-5?
LM385BDR-2-5 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM385BDR-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 LM385BDR-2-5?
For technical support, including LM385BDR-2-5 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM385BDR-2-5 requirements.
6.How does Aetrix verify that LM385BDR-2-5 is sourced from the original manufacturer or authorized distributors?
All LM385BDR-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 LM385BDR-2-5 meets industry standards.
7.What is the process for return or replacement of LM385BDR-2-5?
All LM385BDR-2-5 units undergo pre-shipment inspection (PSI). If there is an issue with LM385BDR-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 LM385BDR-2-5 part is unused and in its original packaging.
Return procedure for LM385BDR-2-5:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM385BDR-2-5 Tags
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