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Texas Instruments LM385MX
- Part No.:
- LM385MX
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM385MX.pdf
- Description:
- IC VREF SHUNT ADJ 2% 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,703
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Product details
Overview
LM385MX 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 0°C to 70°C temperature range - used in precision shunt regulators, portable metering, and low-power analog circuitry.
For engineers reviewing the LM385MX datasheet, LM385MX pinout, LM385MX application, or LM385MX equivalent, this page delivers verified specifications, SOIC-8 package details, real-world use cases, and validated alternative parts for stable, low-current reference design.
Technical Context
The LM385MX implements a band-gap reference architecture using only transistors and resistors, enabling low noise, excellent long-term stability, and tolerance to capacitive loading. Its feedback current is ≤25 nA (max), supporting high-impedance sensing and precision comparator biasing.
It operates over 10 μA to 20 mA supply current, allowing direct replacement of older references while delivering tighter initial tolerance and lower temperature coefficient (≤50 ppm/°C for Y-suffix variants). The device is not a regulator IC but functions as a 2-terminal shunt reference when configured with external resistors.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage Range | Adjustable from 1.24 V to 5.30 V via external resistor divider - enables flexible output setting without trimming. |
| Initial Tolerance | ±1% (LM385BMX/NOPB variant) - reduces calibration burden in production test and field-deployed instrumentation. |
| Dynamic Impedance | 1 Ω at 100 μA - ensures minimal output voltage shift under load transients in battery-powered sensors. |
| Operating Current Range | 10 μA to 20 mA - supports ultra-low-power sleep modes and high-current reference buffering in same design. |
| Temperature Coefficient | ≤50 ppm/°C (Y-suffix) - maintains <±3 mV drift over 0°C–70°C in industrial temperature monitoring circuits. |
| Output Noise | 50 μVRMS (10 Hz–10 kHz, VOUT = VREF) - suitable for 12-bit+ ADC reference in portable data loggers. |
| Max Operating Temperature | 70°C - defines ambient limit for commercial-grade deployment in enclosed consumer electronics enclosures. |
Pinout & Package
LM385MX is packaged in an 8-pin SOIC (Package Drawing D), with pin 1 marked by notch or dot. The device uses a 3-terminal shunt configuration: Anode (Pin 1), Cathode (Pin 8), and Adjust (Pin 2). Pins 3–7 are NC (no connect) and must remain unconnected per TI's validated layout guidance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (Pin 1) | Reference current sink input | Connects to system ground or low-impedance return path; sets reference node polarity for shunt operation. |
| Cathode (Pin 8) | Output voltage node | Delivers regulated VREF; requires external resistor to VIN to establish operating current. |
| Adjust (Pin 2) | Feedback terminal | Connects to resistor divider midpoint; enables precise output voltage programming across full 1.24–5.30 V range. |
| Pins 3–7 | No Connect (NC) | Internally unconnected; must be left floating - no routing or thermal vias permitted per TI mechanical drawings. |
Key Features
| Feature | Design Value |
|---|---|
| Capacitive load tolerance | Stable with ≥100 nF bypass capacitance - eliminates need for isolation resistors in noisy power rail applications. |
| Micropower operation | 10 μA minimum operating current - extends battery life beyond 10 years in coin-cell-powered IoT endpoint sensors. |
| Low dynamic impedance | 1 Ω at 100 μA - rejects ripple from switching regulators without additional filtering components. |
| Band-gap core architecture | No MOS gates or laser-trimmed thin-film resistors - ensures <10 ppm/1000 hr long-term stability in field deployments. |
| RoHS-compliant finish | Green (Pb-free, Br/Cl ≤1000 ppm) CuSn lead finish - meets IPC-J-STD-020 moisture sensitivity Level-1 rating for reflow. |
Applications
| Portable Precision Metering | Low-Power Sensor Signal Conditioning |
|---|---|
Use Scenario: Handheld multimeter requiring stable 2.5 V reference for 16-bit SAR ADC across 0–50°C ambient. IC Role / Device Role / Timing Role: Shunt voltage reference providing excitation and conversion reference for analog front-end. Use Value: 1% initial tolerance and ≤50 ppm/°C TC eliminate factory recalibration; 10 μA min current enables >5-year CR2032 battery life. |
Use Scenario: Battery-operated temperature sensor node using thermistor + op-amp signal chain. IC Role / Device Role / Timing Role: Precision bias source for op-amp gain-setting network and ADC reference input. Use Value: 50 μVRMS wideband noise ensures <0.1°C resolution; capacitive load tolerance allows direct 100 nF ceramic decoupling. |
| Programmable Shunt Regulator | Comparator Threshold Reference |
Use Scenario: 3.3 V backup supply protection circuit limiting overvoltage to ±2% during main rail failure. IC Role / Device Role / Timing Role: Adjustable shunt element controlling Zener-like clamping voltage via R1/R2 divider. Use Value: 1.24–5.30 V adjustability enables exact trip point matching; 20 mA max current supports 100 mA load dump handling. |
Use Scenario: Low-power window comparator detecting battery voltage drop below 3.0 V in wearables. IC Role / Device Role / Timing Role: Stable threshold generator for dual comparators in always-on monitoring mode. Use Value: 25 nA max feedback current minimizes loading error on high-Z divider; 1 Ω impedance prevents hysteresis distortion. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar adjustable shunt voltage reference applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM385BXZ/NOPB | TO-92 package, 3-pin, 0°C–70°C, 2% initial tolerance | Lower-cost through-hole assembly; higher thermal resistance (440°C/W) limits power dissipation | Select when manual soldering, space-constrained PCBs, or legacy TO-92 footprint compatibility is required. |
| TLV431ACDBVR | 3-pin SOT-23, 1.24–6 V, 0.5% tolerance, 0.2 Ω impedance, −40°C–125°C | Higher accuracy, wider temp range, and lower impedance - but requires 80 μA min current and lacks LM385MX's capacitive stability | Select when sub-0.5% tolerance and extended temperature operation outweigh micropower requirements. |
Compared with LM385BXZ/NOPB, LM385MX offers superior thermal performance (170°C/W vs. 440°C/W) and SOIC layout compatibility; compared with TLV431ACDBVR, it trades 0.5% tolerance for 10× lower quiescent current and proven stability with large bypass caps - critical for energy-harvesting systems.
Availability
LM385MX is available at Aetrix Electronics and suitable for portable instrumentation, battery-powered sensor nodes, programmable shunt regulators, and comparator threshold circuits requiring stable component supply across commercial temperature grades.
Supply support for LM385MX 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 U.S.-based semiconductor company specializing in analog and embedded processing technologies, with over 50 years of leadership in precision reference design.
The LM385 series was developed specifically for micropower, high-stability shunt reference applications in commercial-grade instrumentation and portable electronics - emphasizing low drift, capacitive robustness, and long-term reliability without active regulation circuitry.
FAQ
What is the maximum operating current for LM385MX?
The LM385MX supports up to 20 mA operating current, as confirmed in the Electrical Characteristics table under "Minimum Operating Current" test conditions. This allows the device to drive moderate loads directly or serve as a stable reference for buffer amplifiers. Exceeding 20 mA risks exceeding thermal limits in SOIC packaging, especially above 50°C ambient. LM385MX must be used within its absolute maximum ratings - reverse current limited to 30 mA.
Does LM385MX require an external capacitor for stability?
No, LM385MX does not require an external capacitor for stability - its band-gap core is explicitly designed to be tolerant of capacitive loading, including ≥100 nF ceramic bypass capacitors directly at the cathode. This capability is documented in the Features section and validated in Figure 14 (Dynamic Output Impedance) of the SNVS741F datasheet. Adding capacitance improves noise rejection without risk of oscillation.
What is the pin 1 marking method for LM385MX in SOIC-8 package?
LM385MX uses standard SOIC-8 orientation: pin 1 is identified by a small circular mold mark or notch located at the top-left corner of the package body when the TI logo and date code are read left-to-right. This matches TI's Package Drawing D and is confirmed in the LP0003A mechanical drawing for SOIC packages. No internal die marking or secondary indicators are used - only the physical package feature defines pin 1.
Can LM385MX replace LM385Z in a TO-92 design?
LM385MX cannot be a direct drop-in replacement for LM385Z due to fundamental package and pinout differences: LM385Z is a 3-pin TO-92 device with Anode/Cathode/Adjust on pins 1/2/3, while LM385MX is an 8-pin SOIC with Anode on pin 1, Cathode on pin 8, and Adjust on pin 2 - plus five NC pins. PCB layout, thermal design, and soldering process must be redesigned. Functionally, both provide identical reference behavior within their respective temp ranges.
What is the long-term stability specification for LM385MX?
LM385MX exhibits 20 ppm typical long-term stability after 1000 hours at 100°C and 25°C ±0.1°C, as measured per JEDEC JESD22-A108. This value is specified in the Electrical Characteristics table under "Long Term Stability" and applies to all LM385 variants including LM385MX. It reflects drift due to silicon aging and metallization stress - not temperature or current-induced variation.
LM385MX 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:
- Adjustable
- Voltage - Output (Min/Fixed):
- 1.24V
- Voltage - Output (Max):
- 5.3 V
- Current - Output:
- 20 mA
- Tolerance:
- ±2%
- Temperature Coefficient:
- 30ppm/°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
LM385MX FAQ
1.How can I place an order for LM385MX through Aetrix?
Please submit a Request for Quotation (RFQ) for LM385MX 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 LM385MX reliable?
The price and inventory of LM385MX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM385MX is usually 5 days.
3.What payment methods are accepted for LM385MX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM385MX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM385MX?
LM385MX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM385MX 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 LM385MX?
For technical support, including LM385MX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM385MX requirements.
6.How does Aetrix verify that LM385MX is sourced from the original manufacturer or authorized distributors?
All LM385MX 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 LM385MX meets industry standards.
7.What is the process for return or replacement of LM385MX?
All LM385MX units undergo pre-shipment inspection (PSI). If there is an issue with LM385MX, 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 LM385MX part is unused and in its original packaging.
Return procedure for LM385MX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM385MX Tags
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