Texas Instruments LM385Z-2.5/LFT1

Overview

LM385Z-2.5/LFT1 from Texas Instruments is a 2-terminal micropower band-gap voltage reference delivering a precise 2.5 V output with ±20 mV (±0.8%) initial tolerance, 0.6 Ω dynamic impedance (A grade), and operation over 20 μA–20 mA current range. It serves as a stable reference in portable meters, battery-powered analog circuits, and precision current sources where low quiescent current and temperature stability are critical.

For engineers reviewing the LM385Z-2.5/LFT1 datasheet, LM385Z-2.5/LFT1 pinout, LM385Z-2.5/LFT1 application, or LM385Z-2.5/LFT1 equivalent, key selection considerations include its TO-92 package, 0°C to 70°C operating temperature range, 30 ppm/°C max average temperature coefficient (X suffix), and compatibility with capacitive loads up to 10 μF without instability.

Technical Context

The LM385Z-2.5/LFT1 implements a two-terminal band-gap reference architecture using on-chip trimmed resistors and transistors to achieve tight voltage accuracy and low long-term drift. Its design eliminates the need for external biasing components and supports direct connection in series with load or current-setting resistor.

It features exceptionally low dynamic impedance (0.6 Ω at 100 μA, 20 Hz) and wideband noise of 120 μV_rms (10 Hz–10 kHz), enabling high-precision ADC/DAC reference and low-noise sensor excitation applications without additional filtering.

Key Specifications

Pinout & Package

LM385Z-2.5/LFT1 is housed in a 3-pin TO-92 plastic package (Package Drawing LP0003A) with straight or formed leads. Pin 1 is anode, Pin 2 is cathode, and Pin 3 is internally connected to the die attach pad and may be left floating or tied to Pin 2 per TI recommendation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM385BXZ-2.5/NOPB, LM385Z-2.5/LFT1 delivers 2.2× tighter initial tolerance and 40% lower temperature drift; versus REF3025AIDBZR, it consumes 40% less current and uses a simpler 2-terminal topology, though with relaxed absolute accuracy.

Availability

LM385Z-2.5/LFT1 is available at Aetrix Electronics and suitable for portable instrumentation, battery-powered sensors, and precision analog signal conditioning requiring stable component supply across industrial and medical OEM programs.

Supply support for LM385Z-2.5/LFT1 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, embedded processing, and high-reliability ICs for industrial, automotive, and consumer markets.

The LM385 series was designed specifically for micropower, 2-terminal voltage reference applications in portable and battery-constrained systems-emphasizing low operating current, capacitive-load stability, and robust long-term performance.

FAQ

What is the operating temperature range for LM385Z-2.5/LFT1?

The LM385Z-2.5/LFT1 is rated for operation from 0°C to +70°C, consistent with the LM385-2.5-N family specification. This range is validated per TI's SNVS743D datasheet and applies to all electrical characteristics unless otherwise noted. The device is not specified for extended industrial (−40°C to +85°C) or military (−55°C to +125°C) temperature ranges - those require LM285-2.5-N or LM185-2.5-N variants respectively.

Does LM385Z-2.5/LFT1 require an external capacitor for stability?

No, the LM385Z-2.5/LFT1 does not require an external capacitor for stability. Its design is exceptionally tolerant of capacitive loading, remaining stable with output capacitances up to 10 μF. This eliminates the need for series isolation resistors in most applications, simplifying layout and improving transient response in battery-powered systems.

What is the pin configuration and marking for LM385Z-2.5/LFT1 in TO-92 package?

The LM385Z-2.5/LFT1 uses a standard 3-pin TO-92 package (Drawing LP0003A) with Pin 1 = Anode, Pin 2 = Cathode, and Pin 3 = Die Attach Pad (internally connected to substrate). Device marking is "LM385 Z2.5" printed on the top surface. Pin 3 may be left floating or connected to Pin 2 to enhance thermal coupling without affecting electrical function.

How does the dynamic impedance of LM385Z-2.5/LFT1 affect load regulation?

The LM385Z-2.5/LFT1 has a dynamic impedance of 0.6 Ω at 100 μA and 20 Hz. This low value means that a 1 mA change in load current causes only ~0.6 mV output shift - critical for maintaining accuracy in precision current sources and ADC references. Lower dynamic impedance directly improves load regulation performance compared to higher-impedance references like standard Zeners.

Can LM385Z-2.5/LFT1 replace a 2.5 V Zener diode in existing designs?

Yes, LM385Z-2.5/LFT1 can directly replace many 2.5 V Zener diodes in 2-terminal configurations, offering superior initial accuracy (±0.8% vs. ±5% typical for Zeners), lower dynamic impedance (0.6 Ω vs. 10–100 Ω), and better temperature stability. No circuit modification is needed beyond verifying that the operating current stays within 20 μA–20 mA and that the TO-92 footprint matches.