Texas Instruments LM385BLPE3-2-5

Overview

LM385BLPE3-2-5 from Texas Instruments is a micropower, two-terminal, band-gap shunt voltage reference delivering a precise 2.5 V output with ±0.75% initial tolerance (2.462 V to 2.538 V), 1.5 Ω max reference impedance over full temperature range, and ±20 ppm/°C average temperature coefficient across 0°C to 70°C. It operates from 20 μA to 20 mA cathode current and is used in portable meter references and battery-operated analog signal conditioning circuits.

For engineers reviewing the LM385BLPE3-2-5 datasheet, LM385BLPE3-2-5 pinout, LM385BLPE3-2-5 application, or LM385BLPE3-2-5 equivalent, key selection criteria include minimum cathode current (8–20 μA), low dynamic impedance stability under capacitive loading, long-term drift (±20 ppm/khr), and TO-92 package suitability for space-constrained, low-power designs.

Technical Context

The LM385BLPE3-2-5 implements a floating shunt topology with internal band-gap core and high-gain amplifier driving a shunt pass element. Regulation requires only a minimum cathode current - no anode connection to supply rail - enabling both positive and negative reference configurations.

Its on-chip trimming ensures tight initial voltage accuracy, while internal frequency compensation provides stable operation with up to 0.1 μF ceramic bypass capacitance on the cathode node. The device exhibits low broadband noise (120 µV RMS, 10 Hz–10 kHz) and maintains ≤1.5 Ω reference impedance across its full operating current and temperature range.

Key Specifications

Pinout & Package

LM385BLPE3-2-5 uses the TO-92 (LP) package: 3-pin through-hole plastic case, 4.30 mm × 4.30 mm body, lead spacing 1.27 mm, intended for manual assembly or wave soldering in cost-sensitive, low-volume instrumentation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM385LP-2-5, LM385BLPE3-2-5 delivers tighter initial accuracy and lower drift for metrology-grade applications; versus REF3025AIDBZR, it offers shunt flexibility and lower quiescent current but requires external current-setting components.

Availability

LM385BLPE3-2-5 is available at Aetrix Electronics and suitable for portable test instruments, battery-operated sensor nodes, and current-loop transmitters requiring stable component supply with guaranteed long-term continuity and traceable sourcing.

Supply support for LM385BLPE3-2-5 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 headquartered in Dallas, Texas, designing and manufacturing analog ICs, embedded processors, and connectivity solutions for industrial, automotive, and personal electronics markets.

LM385BLPE3-2-5 belongs to TI's precision voltage reference product line, engineered specifically for low-power, high-stability analog signal chains in portable and battery-constrained instrumentation where size, accuracy, and longevity are critical.

FAQ

What is the minimum cathode current required for regulation in the LM385BLPE3-2-5?

The LM385BLPE3-2-5 requires a minimum cathode current (IZ(MIN)) of 8 μA to 20 μA across its operating temperature range (0°C to 70°C). At 25°C, regulation is guaranteed above 20 μA per Electrical Characteristics table; design margin should maintain ≥25 μA to ensure stability under worst-case conditions. This value directly determines the maximum series resistor value when deriving current from a fixed supply.

Can the LM385BLPE3-2-5 be used in a series reference configuration?

No, the LM385BLPE3-2-5 is a two-terminal shunt reference and cannot operate as a series reference. It must be connected with current sourced into the CATHODE pin while the ANODE pin is tied to a common reference point (typically ground). Attempting series connection violates its internal topology and will prevent proper regulation. For series topology, consider TI's REF3025 or REF5025 families instead.

What is the maximum allowable cathode current for continuous operation of the LM385BLPE3-2-5?

The absolute maximum reverse current (IR) rating for LM385BLPE3-2-5 is 30 mA. However, sustained operation above 20 mA risks exceeding thermal limits in the TO-92 package, especially at elevated ambient temperatures. Derating is required: at 70°C ambient, maximum recommended cathode current is ~12 mA to maintain junction temperature below 150°C. Always verify power dissipation (P = 2.5 V × IZ) and PCB copper area.

Does the LM385BLPE3-2-5 require an external capacitor on the cathode pin?

An external capacitor is optional but recommended: a 0.1 μF ceramic capacitor placed directly at the CATHODE pin significantly improves high-frequency noise rejection and transient response. The LM385BLPE3-2-5's internal compensation ensures stability with this value; larger capacitors (>1 μF) may cause oscillation. No series resistor is needed - direct connection to low-ESR ceramic is optimal for portable meter and sensor node applications.

How does the LM385BLPE3-2-5 differ from the standard LM385-2.5 in performance?

The LM385BLPE3-2-5 is the B-grade variant of the LM385 family, featuring tighter initial voltage tolerance (±0.75% vs. ±1.5% for LM385-2.5), improved reference impedance (≤1.0 Ω typical at 25°C vs. ≤1.0 Ω for LM385-2.5 but same 1.5 Ω max), and identical ±20 ppm/°C tempco. Both share the same TO-92 LP package, 20 μA–20 mA operating range, and pinout - making LM385BLPE3-2-5 a drop-in upgrade where enhanced accuracy is required.