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Texas Instruments LM385BPW-1-2
- Part No.:
- LM385BPW-1-2
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- 8-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LM385BPW-1-2.pdf
- Description:
- IC VREF SHUNT 1% 8TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,013
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Product details
Overview
LM385BPW-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 0°C to 70°C. It serves as a precision shunt reference in portable test instruments, battery-operated analog front-ends, and current-loop transmitters.
For engineers reviewing the LM385BPW-1-2 datasheet, LM385BPW-1-2 pinout, LM385BPW-1-2 application, or LM385BPW-1-2 equivalent, key selection criteria include initial tolerance (1.223–1.247 V at 25°C), low-noise operation (60 μV broadband, 10 Hz–10 kHz), capacitive load tolerance, long-term stability (±20 ppm/khr), and TSSOP-8 package compatibility with space-constrained PCB layouts.
Technical Context
The LM385BPW-1-2 implements a floating shunt topology with internal band-gap core, high-gain amplifier, and frequency-compensated loop-enabling stable regulation without external compensation even under capacitive loading. Its design supports both positive and negative regulation configurations by referencing cathode-to-anode voltage.
It operates exclusively in fixed-voltage reference mode with no adjustability; regulation initiates only after minimum cathode current (15 μA) is supplied. Thermal performance is characterized by RθJA = 149 °C/W in the TSSOP-8 (PW) package, with ESD ratings of ±2000 V HBM and ±1000 V CDM.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage | 1.235 V nominal at 25°C; tight 1.223–1.247 V range enables <1% initial accuracy in precision ADC biasing and sensor excitation circuits. |
| Tempco | ±20 ppm/°C over full range; ensures ≤2.5 mV drift across 0°C–70°C for stable calibration in portable meters. |
| Ref Impedance | 1.5 Ω max over full temperature range; maintains regulation integrity under dynamic load shifts in battery-powered systems. |
| Operating Current | 15 μA to 20 mA cathode current; supports ultra-low-power sleep modes and high-current transient response in same device. |
| Noise (10 Hz–10 kHz) | 60 μV rms; minimizes error contribution in high-resolution data acquisition and precision DAC references. |
| Long-Term Stability | ±20 ppm/khr at 100 μA; guarantees <0.2% output drift over 10 years in unattended monitoring equipment. |
Pinout & Package
TSSOP-8 (PW) package: 3.00 mm × 4.40 mm body, 1.2 mm max height, RoHS-compliant NiPdAu lead finish, MSL Level-1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (Pin 2) | Shunt current/voltage input | Main regulation node: current sourced into this pin develops reverse bias across internal band-gap cell; must exceed 15 μA for regulation. |
| Anode (Pin 6) | Common reference terminal | Connected to system ground or negative rail; defines 0 V reference point for output voltage measurement. |
| NC (Pins 1, 3, 4, 5, 7, 8) | No internal connection | Unbonded die pads; must remain unconnected on PCB to avoid parasitic coupling or thermal stress. |
Key Features
| Feature | Design Value |
|---|---|
| Floating shunt architecture | Enables bidirectional use-supports both high-side and low-side reference configurations without polarity constraints. |
| Capacitive load immunity | Stable with ≥0.1 μF ceramic bypass on cathode; eliminates need for external compensation in compact layouts. |
| Micropower operation | 15 μA minimum operating current extends battery life in portable instrumentation beyond shelf-life limits. |
| On-chip trimming | Delivers 1% initial tolerance without external calibration-reduces BOM count and production test time. |
| Low thermal resistance | RθJA = 149 °C/W in TSSOP-8 allows >100 mW power dissipation at ambient ≤50°C without heatsinking. |
Applications
| Portable Test Instruments | Battery-Operated Systems |
|---|---|
Use Scenario: Handheld multimeters requiring stable 1.2 V reference for 4½-digit ADC scaling and auto-zero calibration. IC Role / Device Role / Timing Role: Shunt voltage reference establishing precise scale factor for analog-to-digital conversion and offset nulling. Use Value: ±20 ppm/°C tempco and 60 μV noise ensure <0.01% measurement repeatability across field operating temperatures. |
Use Scenario: Wireless sensor nodes powered by coin-cell batteries needing multi-year operational life. IC Role / Device Role / Timing Role: Low-quiescent-current reference for LDO feedback divider and microcontroller ADC reference. Use Value: 15 μA minimum current enables sleep-mode current budgets below 20 μA while maintaining reference integrity. |
| Current-Loop Instrumentation | Panel Meters |
Use Scenario: 4–20 mA transmitter modules converting sensor outputs with galvanically isolated output stages. IC Role / Device Role / Timing Role: Precision shunt reference setting loop current threshold and span in op-amp-based I/V conversion. Use Value: 1.5 Ω max impedance prevents gain error drift during 4–20 mA ramp tests and improves linearity over full range. |
Use Scenario: Industrial panel meters with LED/LCD displays requiring stable reference for analog bar-graph drivers and digit scaling. IC Role / Device Role / Timing Role: Fixed-voltage reference for analog comparator thresholds and display driver bias networks. Use Value: Long-term stability (±20 ppm/khr) ensures calibration validity over 5+ years without field recalibration. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar shunt voltage reference applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM385BDR-1-2 | SOIC-8 package (4.90 mm × 3.91 mm); RθJA = 95 °C/W; identical electrical specs and 0°C–70°C rating. | Better thermal performance in board-space-tolerant designs; requires larger footprint than TSSOP-8. | Select when higher power dissipation (>150 mW) or legacy SOIC layout compatibility is required. |
| REF3012AIDBZR | 1.2 V output, 50 ppm/°C tempco, 3.5 μA quiescent, SOT-23-3; tighter initial tolerance (0.2%), but higher noise (120 μV). | Lower power and smaller size, but reduced temperature stability and higher noise limit use in precision metrology. | Select for ultra-low-power (<5 μA) applications where ±50 ppm/°C drift is acceptable and board area is critical. |
Compared with LM385BDR-1-2, LM385BPW-1-2 trades thermal efficiency for 40% smaller footprint; compared with REF3012AIDBZR, it delivers superior temperature stability and lower noise at the cost of higher minimum operating current.
Availability
LM385BPW-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 availability and consistent parametric performance.
Supply support for LM385BPW-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 specializing in analog and embedded processing technologies, with leadership in precision analog ICs and industrial-grade components.
The LM385B series was designed specifically for micropower, high-stability shunt voltage reference applications in portable, battery-constrained, and industrial measurement systems-emphasizing low drift, load immunity, and long-term reliability.
FAQ
What is the minimum cathode current required for regulation in the LM385BPW-1-2?
The LM385BPW-1-2 requires a minimum cathode current of 15 μA to achieve proper regulation. This value is specified in the Electrical Characteristics table under "Minimum reference current" for the LM385B-1.2 variant. Operating below this threshold results in undefined output voltage and loss of temperature stability. The LM385BPW-1-2 must be biased with a current source or resistor network ensuring ≥15 μA across its full operating temperature range (0°C to 70°C).
Does the LM385BPW-1-2 support adjustable output voltage?
No, the LM385BPW-1-2 is a fixed-output shunt voltage reference with no adjustment capability. Its 1.235 V nominal output is set by internal band-gap and trimming circuitry. The device operates exclusively in one functional mode-as a two-terminal shunt regulator-and does not include pins, external resistors, or control interfaces for voltage programming. Any attempt to modify output via external components violates its specified operating conditions and voids parametric guarantees.
Can the LM385BPW-1-2 be used in negative-reference configurations?
Yes, the LM385BPW-1-2 supports negative-reference configurations due to its floating shunt architecture. When the anode is connected to a negative rail and the cathode to signal ground, it establishes a stable −1.235 V reference relative to ground. This configuration is explicitly supported in TI's Functional Block Diagram and Device Functional Modes section, which confirms utility in both positive and negative regulation topologies-provided cathode current remains within 15 μA to 20 mA and thermal limits are observed.
What is the maximum allowable cathode current for continuous operation of the LM385BPW-1-2?
The absolute maximum reverse current rating for the LM385BPW-1-2 is 30 mA, per Absolute Maximum Ratings. However, for reliable continuous operation, cathode current must be limited to ensure junction temperature stays below 150°C. With RθJA = 149 °C/W and ambient ≤50°C, maximum safe continuous current is ~13.4 mA at 1.235 V (16.5 mW dissipation). Exceeding this risks thermal runaway or accelerated long-term drift; derating is recommended for high-reliability applications.
Is a bypass capacitor required on the cathode pin of the LM385BPW-1-2?
Yes, TI recommends a 0.1 μF low-ESR ceramic capacitor directly between cathode (Pin 2) and ground. This capacitor stabilizes the internal control loop under capacitive loading, suppresses broadband noise (60 μV), and improves transient response-especially critical in battery-operated systems with variable supply impedance. Layout guidelines specify placement within 2 mm of the pin and connection to a solid ground plane to minimize inductance and EMI pickup.
LM385BPW-1-2 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- 8-TSSOP (0.173", 4.40mm Width)
- Series:
- -
- Packaging:
- Tray
- 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-TSSOP
LM385BPW-1-2 FAQ
1.How can I place an order for LM385BPW-1-2 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM385BPW-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 LM385BPW-1-2 reliable?
The price and inventory of LM385BPW-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 LM385BPW-1-2 is usually 5 days.
3.What payment methods are accepted for LM385BPW-1-2?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM385BPW-1-2 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM385BPW-1-2?
LM385BPW-1-2 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM385BPW-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 LM385BPW-1-2?
For technical support, including LM385BPW-1-2 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM385BPW-1-2 requirements.
6.How does Aetrix verify that LM385BPW-1-2 is sourced from the original manufacturer or authorized distributors?
All LM385BPW-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 LM385BPW-1-2 meets industry standards.
7.What is the process for return or replacement of LM385BPW-1-2?
All LM385BPW-1-2 units undergo pre-shipment inspection (PSI). If there is an issue with LM385BPW-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 LM385BPW-1-2 part is unused and in its original packaging.
Return procedure for LM385BPW-1-2:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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