Texas Instruments LM385BPWE4-2-5

Overview

LM385BPWE4-2-5 from Texas Instruments is a micropower, two-terminal, band-gap shunt voltage reference delivering a precise 2.5 V output with ±1.5% initial tolerance (LM385B grade), 1.5 Ω max reference impedance over full temperature range, and 20 μA to 20 mA operating current. It serves as a stable reference in portable battery-powered instrumentation requiring low quiescent current and high capacitive-load tolerance.

For engineers reviewing the LM385BPWE4-2-5 datasheet, LM385BPWE4-2-5 pinout, LM385BPWE4-2-5 application, or LM385BPWE4-2-5 equivalent, key selection criteria include its 2.5 V nominal output, 20 μA minimum cathode current requirement, ±20 ppm/°C tempco, TSSOP-8 package footprint, and suitability for precision analog circuits where micropower operation and long-term stability are critical.

Technical Context

The LM385BPWE4-2-5 implements a floating shunt architecture using an internal band-gap reference and high-gain amplifier to regulate voltage between cathode and anode. Its design enables stable operation with any capacitive load and supports both positive and negative regulation topologies.

It operates exclusively in a single functional mode: fixed 2.5 V shunt reference. Regulation requires sourcing ≥20 μA into the cathode; no external adjustment or configuration is possible. The device exhibits 120 µV broadband noise (10 Hz–10 kHz) and ±20 ppm/khr long-term drift at 100 μA cathode current.

Key Specifications

Pinout & Package

TSSOP-8 package (3.00 mm × 4.40 mm body, 0.65 mm pitch), 1.2 mm max height, RoHS-compliant NiPdAu lead finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM385PWR-2-5, LM385BPWE4-2-5 offers tighter initial tolerance for uncalibrated systems; compared with REF3025AIDBZR, it trades absolute accuracy for micropower operation and TSSOP compatibility - making it optimal for space-constrained, long-life portable instruments.

Availability

LM385BPWE4-2-5 is available at Aetrix Electronics and suitable for portable test instrumentation, battery-operated panel meters, and current-loop transmitters requiring stable component supply with guaranteed long-term availability.

Supply support for LM385BPWE4-2-5 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 specializing in analog and embedded processing technologies, with leadership in precision analog ICs and industrial-grade components.

The LM385B series was designed specifically for micropower, high-stability shunt voltage references in portable and battery-critical applications - emphasizing low I_MIN, capacitive-load robustness, and long-term reliability.

FAQ

What is the minimum cathode current required for regulation in the LM385BPWE4-2-5?

The LM385BPWE4-2-5 requires a minimum cathode current of 20 μA to maintain regulation at 2.5 V. Below this threshold, the reference voltage collapses and becomes undefined. This value is specified across the full 0°C to 70°C operating range and is critical for designing battery-powered circuits where quiescent current directly impacts runtime. The LM385BPWE4-2-5 datasheet confirms this in Section 6.3 (Recommended Operating Conditions) and Electrical Characteristics Table.

Is the LM385BPWE4-2-5 pin-compatible with other LM385 variants in TSSOP-8?

Yes, the LM385BPWE4-2-5 shares identical pinout and package dimensions with all LM385x-2-5 TSSOP-8 variants (e.g., LM385PWR-2-5), including Anode on Pin 4 and Cathode on Pin 8. However, electrical differences exist: LM385BPWE4-2-5 uses the LM385B grade (±1.5% tolerance), while standard LM385 versions offer ±3%. No PCB redesign is needed for substitution, but system-level accuracy validation is required.

Can the LM385BPWE4-2-5 be used in negative-reference configurations?

Yes, the LM385BPWE4-2-5 supports floating shunt operation and can be configured as a negative reference by reversing its connection: Anode tied to V_CC and Cathode to the regulated negative node. Its two-terminal architecture and internal band-gap design enable bidirectional use without external components. This is explicitly supported in the Functional Description (Section 7.3) and Application Examples (Figure 10) of the LM385BPWE4-2-5 datasheet.

What is the maximum capacitive load the LM385BPWE4-2-5 can drive without oscillation?

The LM385BPWE4-2-5 has no specified maximum capacitive load - its internal frequency compensation ensures stability with unlimited capacitance on the Cathode pin. This eliminates the need for series isolation resistors commonly required with older shunt references. The datasheet states "exceptionally tolerant of capacitive loading" and confirms stable operation in Figure 12 layout examples with 0.1-μF ceramic bypass caps. This feature simplifies noise-sensitive designs like precision ADC references.

Does the LM385BPWE4-2-5 require a heatsink in typical operation?

No, the LM385BPWE4-2-5 does not require a heatsink under normal conditions. With a maximum cathode current of 20 mA and 2.5 V drop, power dissipation remains ≤50 mW. Its TSSOP-8 package has a junction-to-ambient thermal resistance (R_θJA) of 168.3°C/W, resulting in <8.5°C temperature rise above ambient - well within safe limits. Heatsinking is unnecessary unless operating continuously at >20 mA in high-ambient (>70°C) environments.