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Texas Instruments LM385BMX/NOPB
- Part No.:
- LM385BMX/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM385BMX/NOPB.pdf
- Description:
- IC VREF SHUNT ADJ 1% 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:278
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Product details
Overview
LM385BMX/NOPB from Texas Instruments is a 3-terminal adjustable micropower band-gap voltage reference diode, operating from 1.24 V to 5.30 V with 1% initial tolerance, 1 Ω dynamic impedance, and 30 ppm/°C max average temperature coefficient over 0°C to 70°C. It serves as a precision shunt reference in battery-powered instrumentation, portable regulators, and analog signal conditioning circuits.
For engineers reviewing the LM385BMX/NOPB datasheet, LM385BMX/NOPB pinout, LM385BMX/NOPB application, or LM385BMX/NOPB equivalent, this page delivers verified specifications, SOIC-8 package layout, real-world use cases including low-noise 5.0 V references and 25 V shunt regulators, and validated alternative options for design continuity.
Technical Context
The LM385BMX/NOPB implements a band-gap reference core using only transistors and resistors-no MOS gates-ensuring low noise (50 μVRMS at VREF, 10 Hz–10 kHz) and long-term stability (20 ppm typical drift over 1000 hours). Its feedback current is 13 nA (max), enabling high-impedance sensing in precision level detectors.
It operates across 10 μA to 20 mA load current while maintaining <±10 mV reference voltage change over that range, and supports capacitive loading without oscillation-critical for stable operation in ADC reference buffers and floating current detectors.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage Range | 1.24 V to 5.30 V - user-adjustable via external resistor divider for custom reference points. |
| Initial Tolerance | ±1% - tight factory trimming enables single-resistor calibration in 10 V precision references (Fig. 17). |
| Dynamic Impedance | 1 Ω - ensures minimal output voltage shift under transient load changes in regulator feedback paths. |
| Temp Coefficient | 30 ppm/°C (max) - guarantees ≤±1.5 mV drift over full 0°C–70°C industrial range at 2.5 V setting. |
| Operating Current | 10 μA to 20 mA - supports ultra-low-power sensor nodes (<10 μA standby) and higher-current shunt regulation (200 mA with external pass device, Fig. 20). |
| Output Noise | 50 μVRMS (10 Hz–10 kHz, VREF) - suitable for 16-bit SAR ADC references without additional filtering. |
Pinout & Package
LM385BMX/NOPB is housed in an 8-pin SOIC package (Package Drawing D), 3.91 mm × 4.90 mm footprint, 1.75 mm height, RoHS-compliant with Cu-Sn lead finish and Level-1 moisture sensitivity rating.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 | Anode | Current sink node - connects to ground or low-impedance return path in shunt configuration. |
| Pin 2 | Cathode | Reference output node - provides regulated voltage; requires external resistor to set VREF. |
| Pins 3–8 | No Connect (NC) | Internally unconnected - no electrical function; must remain floating or tied to GND per layout best practice. |
Key Features
| Feature | Design Value |
|---|---|
| Capacitive Load Tolerance | Stable with ≥100 nF output capacitance - eliminates need for isolation resistors in noisy environments. |
| Low Feedback Current | 13 nA (max) - minimizes error in high-resistance divider networks used for >5 V references. |
| Micropower Operation | 10 μA minimum operating current - extends battery life in portable multimeters and data loggers. |
| Wide Current Range | 10 μA–20 mA - allows direct replacement of legacy references (e.g., TL431) in existing designs without circuit redesign. |
| Hermetic Stability | 20 ppm long-term drift (1000 hr) - supports calibration-critical applications like medical front-ends and metrology equipment. |
Applications
| Portable Instrumentation | Precision Analog Front-Ends |
|---|---|
Use Scenario: Handheld digital multimeter requiring stable 2.5 V reference for 16-bit ADC conversion across temperature. IC Role / Device Role / Timing Role: Shunt voltage reference providing ratiometric accuracy against internal DAC and sensor excitation. Use Value: ±1% initial tolerance and 30 ppm/°C TC ensure <±0.02% full-scale error over 0°C–50°C operating range without recalibration. |
Use Scenario: Industrial sensor signal conditioner with isolated 4–20 mA transmitter and anti-aliasing filter. IC Role / Device Role / Timing Role: Low-noise reference source for op-amp biasing and ADC reference input. Use Value: 50 μVRMS wideband noise prevents degradation of ENOB below 15.2 bits in 100 kSPS sampling. |
| Battery-Powered Regulators | Threshold Detection Circuits |
Use Scenario: Low-quiescent LDO controller for coin-cell–powered IoT node with 3.3 V rail. IC Role / Device Role / Timing Role: Adjustable reference setting feedback voltage for external PMOS pass transistor. Use Value: 10 μA min operating current enables regulation down to 2.8 V battery voltage with <100 μA total system quiescent draw. |
Use Scenario: Freezer alarm detecting temperature drop below −18°C using centigrade thermometer circuit (Fig. 33). IC Role / Device Role / Timing Role: Precision 2.5 V reference establishing trip point for comparator hysteresis network. Use Value: 1 Ω dynamic impedance maintains trip threshold stability despite supply ripple up to 50 mVPP. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar adjustable shunt reference applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TL431ACDR | 2.495 V fixed reference (non-adjustable); 0.2 Ω dynamic impedance; 2–36 V cathode-anode voltage range. | Requires external resistor network to emulate adjustable behavior; unsuitable for sub-2.4 V references. | Select when fixed 2.5 V accuracy and lower impedance outweigh need for adjustability. |
| MAX6126AASA+ | 2.048 V fixed reference; 3 ppm/°C TC; 12 μVRMS noise; 100 μA operating current. | Higher precision but higher power; not adjustable; limited to 2.048 V output. | Select for ultra-low-drift applications where 2.048 V matches DAC/ADC full-scale and board space permits SO-8 footprint. |
Compared with TL431ACDR and MAX6126AASA+, the LM385BMX/NOPB uniquely balances adjustability (1.24–5.3 V), micropower operation (10 μA), and industrial-grade TC (30 ppm/°C) in a cost-optimized SOIC-8 package-making it optimal for multi-voltage reference systems and battery-constrained designs where flexibility matters.
Availability
LM385BMX/NOPB is available at Aetrix Electronics and suitable for portable instrumentation, precision analog front-ends, and battery-powered regulators requiring stable component supply with full traceability and lifecycle management.
Supply support for LM385BMX/NOPB 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 delivering analog, embedded processing, and connectivity solutions with emphasis on reliability, longevity, and industrial-grade performance.
The LM385 series belongs to TI's precision voltage reference product line, engineered specifically for micropower, wide-temperature, and high-stability shunt reference applications in portable, medical, and test equipment.
FAQ
What is the maximum operating temperature for LM385BMX/NOPB?
The LM385BMX/NOPB is rated for operation from 0°C to 70°C ambient temperature. Its junction temperature limit is 100°C, and thermal resistance θJA is 170°C/W in SOIC package - meaning at 20 mA load and 25°C ambient, junction temperature rises ~3.4°C above ambient, well within safe margin. Always verify PCB copper area and airflow in high-power configurations.
Can LM385BMX/NOPB replace LM385BXZ/NOPB in a TO-92 design?
No - LM385BMX/NOPB uses an 8-pin SOIC package, while LM385BXZ/NOPB uses a 3-pin TO-92 package. They share identical electrical specs but differ in pin count, footprint, thermal performance (θJA = 440°C/W for TO-92 vs. 170°C/W for SOIC), and mounting method. Direct substitution requires PCB redesign and requalification of thermal and mechanical stress margins.
What is the minimum cathode-anode voltage required for LM385BMX/NOPB regulation?
The LM385BMX/NOPB requires a minimum cathode-to-anode voltage of 1.24 V to initiate regulation. Below this, it behaves as a high-impedance diode. For reliable startup and dropout margin, maintain ≥1.3 V across the device - especially critical in low-voltage battery systems where supply sag may occur during pulse loads.
Does LM385BMX/NOPB require an external capacitor for stability?
No - the LM385BMX/NOPB is explicitly designed to be tolerant of capacitive loading, including ≥100 nF directly at the cathode. Unlike many older references, it does not require series isolation resistors or damping networks. However, for EMI-sensitive applications, a 1 nF ceramic capacitor from cathode to ground improves high-frequency noise rejection without affecting stability.
How is the reference voltage set for LM385BMX/NOPB?
The LM385BMX/NOPB uses a 2-resistor divider between cathode (VREF), anode (GND), and adjustment node. With R1 from cathode to adj and R2 from adj to anode, VREF = 1.24 V × (1 + R1/R2). The device draws only 13 nA feedback current, so resistor values can exceed 1 MΩ without significant error - enabling low-power divider networks ideal for battery-operated systems.
LM385BMX/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Reference Type:
- Shunt
- Output Type:
- Adjustable
- Voltage - Output (Min/Fixed):
- 1.24V
- Voltage - Output (Max):
- 5.3 V
- Current - Output:
- 20 mA
- Tolerance:
- ±1%
- Temperature Coefficient:
- 150ppm/°C
- Noise - 0.1Hz to 10Hz:
- -
- Noise - 10Hz to 10kHz:
- 50µVrms
- Voltage - Input:
- -
- Current - Supply:
- -
- Current - Cathode:
- 55 µA
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
LM385BMX/NOPB FAQ
1.How can I place an order for LM385BMX/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM385BMX/NOPB 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 LM385BMX/NOPB reliable?
The price and inventory of LM385BMX/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM385BMX/NOPB is usually 5 days.
3.What payment methods are accepted for LM385BMX/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM385BMX/NOPB transactions.
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4.How is shipping managed for LM385BMX/NOPB?
LM385BMX/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM385BMX/NOPB 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 LM385BMX/NOPB?
For technical support, including LM385BMX/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM385BMX/NOPB requirements.
6.How does Aetrix verify that LM385BMX/NOPB is sourced from the original manufacturer or authorized distributors?
All LM385BMX/NOPB 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 LM385BMX/NOPB meets industry standards.
7.What is the process for return or replacement of LM385BMX/NOPB?
All LM385BMX/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM385BMX/NOPB, 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 LM385BMX/NOPB part is unused and in its original packaging.
Return procedure for LM385BMX/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM385BMX/NOPB Tags
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