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Texas Instruments LM385BD-1-2
- Part No.:
- LM385BD-1-2
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM385BD-1-2.pdf
- Description:
- IC VREF SHUNT 1% 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:783
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Product details
Overview
LM385BD-1-2 from Texas Instruments is a micropower, two-terminal band-gap voltage reference IC operating over 15 μA to 20 mA cathode current, delivering 1.235 V nominal output with ±20 ppm/°C temperature coefficient and 1.5 Ω max reference impedance across full temperature range (0°C to 70°C). It serves as a precision shunt reference in portable test instruments and battery-operated analog signal chains.
For engineers reviewing the LM385BD-1-2 datasheet, LM385BD-1-2 pinout, LM385BD-1-2 application, or LM385BD-1-2 equivalent, key selection criteria include initial tolerance (2%), long-term stability (±20 ppm/khr), low-noise operation (60 μV broadband), capacitive load tolerance, and SOIC-8 packaging for surface-mount reliability in space-constrained designs.
Technical Context
The LM385BD-1-2 implements a floating shunt topology with internal band-gap core, high-gain amplifier, and frequency-compensated loop enabling stable regulation under all capacitor loads. Its design eliminates need for external compensation and supports both positive and negative regulation configurations.
It operates exclusively in fixed-voltage reference mode with no adjustability; regulation initiates only after minimum cathode current (15 μA) is supplied, and its low dynamic impedance (≤1.5 Ω) ensures minimal voltage shift across 15 μA–20 mA operating range and full temperature span.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Nominal Voltage | 1.235 V - precise band-gap reference point at 25°C, used for ADC/DAC biasing and sensor excitation |
| Initial Tolerance | ±2% - ensures reference accuracy without post-manufacture trimming in cost-sensitive applications |
| Temp Coefficient | ±20 ppm/°C - enables stable performance across 0°C to 70°C industrial ambient without calibration |
| Ref Impedance | ≤1.5 Ω - maintains <30 mV output shift over full 15 μA–20 mA current range, critical for current-loop transmitters |
| Broadband Noise | 60 μV - low-noise floor supports high-resolution measurement front-ends without added filtering |
| Min Cathode Current | 15 μA - ultra-low startup threshold extends battery life in always-on portable meters |
| Long-Term Drift | ±20 ppm/khr - guarantees <0.02% output change over 1000 hours, suitable for unattended monitoring systems |
Pinout & Package
LM385BD-1-2 is housed in an 8-pin SOIC package (4.90 mm × 3.91 mm body, 1.75 mm max height) with standard JEDEC MS-012AA outline and RoHS-compliant NiPdAu lead finish. Pin 1 is marked by a beveled corner or notch; pins 3, 5, 6, and 7 are internally unconnected.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (Pin 1) | Shunt current input | Current-sink node where regulated 1.235 V appears relative to anode; must receive ≥15 μA for regulation |
| Anode (Pin 2) | Common reference node | Typically connected to system ground or negative rail; defines reference potential for cathode voltage |
| NC (Pins 3,5,6,7) | No internal connection | Unused terminals; must remain unconnected or tied to ground per layout guidelines to avoid parasitic coupling |
Key Features
| Feature | Design Value |
|---|---|
| Floating shunt architecture | Enables bidirectional use-supports both high-side and low-side reference configurations without external components |
| Capacitive load immunity | Stable operation with any value of bypass capacitor on cathode, eliminating need for series resistance or damping networks |
| Low-power micropower operation | 15 μA minimum current allows integration into sub-100 μA standby circuits, extending shelf-life-equivalent battery runtime |
| On-chip trimmed voltage | Eliminates external calibration; achieves 2% initial accuracy without laser trimming or resistor networks |
| Integrated noise filtering | Internal compensation reduces 10 Hz–10 kHz noise to 60 μV RMS, avoiding external RC filters in precision analog stages |
Applications
| Portable Test Instruments | Battery-Operated Systems |
|---|---|
Use Scenario: Handheld multimeters and calibrators requiring stable, low-drift reference for 4½-digit ADCs. IC Role / Device Role / Timing Role: Shunt voltage reference providing excitation for precision resistive dividers and offset correction in analog front-end. Use Value: ±20 ppm/°C tempco and 60 μV noise enable <0.01% measurement accuracy across 0°C–50°C handheld operating range. | Use Scenario: Remote environmental sensors powered by coin cells or energy harvesters with multi-year deployment goals. IC Role / Device Role / Timing Role: Primary reference for low-power microcontroller ADCs and analog comparators in sleep/wake cycles. Use Value: 15 μA min current and ±20 ppm/khr drift ensure >5-year calibration stability without field recalibration. |
| Current-Loop Instrumentation | Panel Meters |
Use Scenario: 4–20 mA transmitter modules converting sensor outputs for industrial process control. IC Role / Device Role / Timing Role: Precision shunt reference setting current-sense resistor voltage in op-amp-based loop drivers. Use Value: ≤1.5 Ω impedance prevents gain error drift under varying loop supply voltages and cable lengths. | Use Scenario: DIN-rail mounted digital panel meters displaying voltage, current, or temperature with LED/LCD readouts. IC Role / Device Role / Timing Role: Stable reference for internal DACs generating analog meter drive signals and scaling ADC inputs. Use Value: Interchangeability with LM285-1.2 and LM385-1.2 simplifies BOM consolidation across legacy and new meter designs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar shunt voltage reference applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM385D-1-2 | 1% initial tolerance (vs. 2%); same SOIC-8 package, 0°C–70°C rating, and 15 μA–20 mA current range | Suitable where tighter initial accuracy is required without changing PCB layout or thermal design | Select LM385D-1-2 when system-level calibration budget demands <1% reference contribution at power-up |
| TLVH431IDBZR | Adjustable 1.24 V reference (2.5 V max), higher 80 μA min cathode current, 0.2 Ω typical impedance, SOT-23-3 package | Used in programmable references and feedback loops where adjustable output or smaller footprint is prioritized | Choose TLVH431IDBZR only if design requires voltage adjustment capability or board space reduction outweighs fixed-reference simplicity |
Compared with LM385D-1-2, LM385BD-1-2 trades 1% initial accuracy for lower cost and broader availability, while TLVH431IDBZR offers configurability at the expense of higher quiescent current and reduced long-term stability-making LM385BD-1-2 optimal for fixed, ultra-low-power, production-grade instrumentation.
Availability
LM385BD-1-2 is available at Aetrix Electronics and suitable for portable test instruments, battery-operated systems, and current-loop instrumentation requiring stable component supply with guaranteed long-term continuity.
Supply support for LM385BD-1-2 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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.
LM385BD-1-2 belongs to TI's precision voltage reference product line, engineered specifically for micropower, high-stability shunt references in portable and battery-constrained applications where low drift and load immunity are critical.
FAQ
What is the operating temperature range for LM385BD-1-2?
The LM385BD-1-2 is specified for operation from 0°C to 70°C ambient temperature. This industrial-grade range is narrower than the −40°C to 85°C range of the LM285-1.2 variant but aligns with its optimized micropower performance and 2% initial tolerance grade. The device maintains all electrical characteristics-including 1.235 V nominal output, ±20 ppm/°C tempco, and ≤1.5 Ω impedance-within this range. Exceeding 70°C may cause parametric shift beyond datasheet limits.
Does LM385BD-1-2 require external capacitors for stability?
No, LM385BD-1-2 does not require external capacitors for stability. Its internal frequency compensation ensures unconditional stability with any capacitive load on the cathode pin, including 0.1 μF ceramic bypass capacitors commonly used for noise suppression. This eliminates risk of oscillation in high-impedance sensor interfaces or battery-powered systems where layout constraints limit decoupling options. TI recommends placing the 0.1 μF capacitor as close as possible to the cathode pin for optimal noise performance.
What is the minimum cathode current needed for regulation in LM385BD-1-2?
The LM385BD-1-2 requires a minimum cathode current of 15 μA to establish and maintain regulation. Below this threshold, the output voltage deviates significantly from 1.235 V and exhibits increased sensitivity to temperature and load changes. This value is confirmed in the Electrical Characteristics table under "Minimum reference current" for LM385B-1.2 devices at full temperature range. Designers must size current-setting resistors or active sources accordingly-e.g., for a 5 V supply, R ≤ (5 V − 1.235 V) / 15 μA ≈ 250 kΩ.
Can LM385BD-1-2 replace LM285-1.2 in existing designs?
LM385BD-1-2 can replace LM285-1.2 in many designs, but only if the operating temperature stays within 0°C–70°C and initial tolerance of ±2% is acceptable. LM285-1.2 supports −40°C to 85°C and offers 1% tolerance, while LM385BD-1-2 has identical SOIC-8 pinout and electrical behavior above 15 μA. However, substituting it in wide-temperature or high-accuracy applications may require validation of drift, noise, and regulation margin across the extended range. Always verify cathode current compliance under worst-case conditions.
What is the reference impedance specification for LM385BD-1-2 and why does it matter?
LM385BD-1-2 has a maximum reference impedance of 1.5 Ω across its full operating temperature range (0°C–70°C) and current range (15 μA–20 mA). This low dynamic impedance means the output voltage shifts less than 30 mV when cathode current varies across its full range-critical for maintaining accuracy in current-loop transmitters, ratiometric sensor interfaces, and precision ADC references. Higher impedance would introduce gain errors proportional to load current variations, degrading system linearity and repeatability.
LM385BD-1-2 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Series:
- -
- Packaging:
- Tube
- Product Status:
- Obsolete
- Reference Type:
- Shunt
- Output Type:
- Fixed
- Voltage - Output (Min/Fixed):
- 1.235V
- Voltage - Output (Max):
- -
- Current - Output:
- 20 mA
- Tolerance:
- ±1%
- Temperature Coefficient:
- 20ppm/°C Typical
- Noise - 0.1Hz to 10Hz:
- -
- Noise - 10Hz to 10kHz:
- 60µVrms
- Voltage - Input:
- -
- Current - Supply:
- -
- Current - Cathode:
- 15 µA
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
LM385BD-1-2 FAQ
1.How can I place an order for LM385BD-1-2 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM385BD-1-2 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-1-2 reliable?
The price and inventory of LM385BD-1-2 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM385BD-1-2 is usually 5 days.
3.What payment methods are accepted for LM385BD-1-2?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM385BD-1-2 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM385BD-1-2?
LM385BD-1-2 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM385BD-1-2 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-1-2?
For technical support, including LM385BD-1-2 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM385BD-1-2 requirements.
6.How does Aetrix verify that LM385BD-1-2 is sourced from the original manufacturer or authorized distributors?
All LM385BD-1-2 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-1-2 meets industry standards.
7.What is the process for return or replacement of LM385BD-1-2?
All LM385BD-1-2 units undergo pre-shipment inspection (PSI). If there is an issue with LM385BD-1-2, 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-1-2 part is unused and in its original packaging.
Return procedure for LM385BD-1-2:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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