Texas Instruments LM385M-1.2

Overview

LM385M-1.2 from Texas Instruments is a micropower 2-terminal band-gap voltage reference diode delivering a precise 1.235 V output with ±1% initial tolerance, 1 Ω dynamic impedance, and 150 ppm/°C temperature coefficient across 0°C to 70°C. It operates over a 10 μA to 20 mA current range and is used in battery-powered precision analog circuits such as portable meters and low-power thermometers.

For engineers reviewing the LM385M-1.2 datasheet, LM385M-1.2 pinout, LM385M-1.2 application, or LM385M-1.2 equivalent, key selection considerations include its SOIC-8 package, 1.235 V nominal reference voltage, micropower operation down to 10 μA, low dynamic impedance, and industrial temperature range suitability.

Technical Context

The LM385M-1.2 implements a band-gap reference architecture using on-chip trimmed transistors and resistors to achieve stable voltage output without external components. Its 2-terminal configuration simplifies integration into biasing, calibration, and current-source circuits.

It exhibits exceptional capacitive loading tolerance and maintains regulation across wide supply variations. The device's low noise (60 μV_rms, 10 Hz–10 kHz) and long-term stability (20 ppm/1000 hr) support high-accuracy measurement systems requiring minimal drift.

Key Specifications

Pinout & Package

LM385M-1.2 is housed in an 8-pin SOIC package (Package Drawing D), with pins 1–8 arranged linearly. Pin 1 is the cathode (reference output), and pin 2 is the anode (current input); pins 3–8 are internally connected to the die attach pad and must be tied to pin 2 or left floating per TI design guidance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar voltage reference applications.

Compared with LM385BZ-1.2/NOPB and LM385M3-1.2/NOPB, the LM385M-1.2 offers superior thermal performance (165°C/W θ_JA) and SOIC-8 layout compatibility with standard op-amp footprints, easing integration into mixed-signal signal chains without redesigning routing or thermal pads.

Availability

LM385M-1.2 is available at Aetrix Electronics and suitable for portable instrumentation, battery-powered sensors, precision current sources, and low-power thermometry requiring stable component supply and long-lifecycle support.

Supply support for LM385M-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 leader specializing in analog and embedded processing technologies, with decades of expertise in precision reference design and high-reliability manufacturing.

The LM385 family was engineered for micropower, low-drift voltage referencing in portable and industrial measurement systems-prioritizing accuracy, stability, and ease of use over wide operating current ranges.

FAQ

What is the nominal output voltage of the LM385M-1.2?

The LM385M-1.2 provides a nominal output voltage of 1.235 V at 25°C with ±1% initial tolerance. This value is specified across its full operating current range (10 μA to 20 mA) and remains stable within 150 ppm/°C over 0°C to 70°C. The LM385M-1.2 achieves this using a band-gap reference core with on-chip trimming, making it suitable for precision analog circuits where absolute voltage accuracy is critical.

Can the LM385M-1.2 operate from a 1.5 V battery?

Yes, the LM385M-1.2 can operate from a 1.5 V battery when configured as a shunt reference with appropriate current limiting. Its minimum operating current is 10 μA, and forward voltage drop is negligible in this mode; the device regulates by sinking current to maintain 1.235 V at the cathode. Figure 16 in the TI datasheet explicitly shows this configuration. The LM385M-1.2 remains stable and accurate under these conditions, supporting ultra-low-voltage portable applications.

What is the maximum reverse current rating for the LM385M-1.2?

The absolute maximum reverse current rating for the LM385M-1.2 is 30 mA, as specified in the Absolute Maximum Ratings table. Exceeding this value risks permanent damage. For reliable operation, the recommended reverse current range is 10 μA to 20 mA per Electrical Characteristics. The LM385M-1.2 delivers optimal stability and low dynamic impedance within this range, and its 1 Ω impedance helps maintain regulation even near the upper limit.

Is the LM385M-1.2 RoHS compliant?

Yes, the LM385M-1.2/NOPB variant is RoHS compliant and features green (halogen-free) packaging with Sn lead finish. This is confirmed in TI's Package Option Addendum, which lists "Green (RoHS & no Sb/Br)" under Eco Plan and "SN" under Lead/Ball Finish. The "NOPB" suffix explicitly denotes lead-free compliance, and the device meets JEDEC MSL Level-1 handling requirements for moisture sensitivity.

How does the LM385M-1.2 differ from the LM385-1.2-N in TO-92?

The LM385M-1.2 differs from the TO-92 packaged LM385-1.2-N primarily in package type (SOIC-8 vs. TO-92), thermal performance (θ_JA = 165°C/W vs. 440°C/W), and pin configuration (8-pin with DAP ties vs. 3-pin discrete). Electrically, both share identical reference voltage (1.235 V), tolerance (±1%), temperature range (0°C to 70°C), and core specifications. The LM385M-1.2 is optimized for automated SMT assembly and better thermal dissipation in dense layouts.