Texas Instruments LM385BZ/NOPB

Overview

LM385BZ/NOPB 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 30 ppm/°C max average temperature coefficient over 0°C to 70°C. It serves as a precision shunt reference in battery-powered meters, low-power regulators, and analog signal conditioning circuits.

For engineers reviewing the LM385BZ/NOPB datasheet, LM385BZ/NOPB pinout, LM385BZ/NOPB application, or LM385BZ/NOPB equivalent, key selection criteria include its TO-92 package compatibility, 10 μA minimum operating current, capacitive-load tolerance, and tight initial voltage accuracy for stable low-power reference design.

Technical Context

The LM385BZ/NOPB implements a band-gap reference architecture using only transistors and resistors-no MOS gates-enabling low noise (50 μV_RMS at V_REF, 10 Hz–10 kHz), excellent long-term stability (20 ppm typical drift over 1000 hours), and robustness against capacitive loading. Its feedback current is limited to 25 nA (max) at 25°C, minimizing error in high-impedance divider networks.

Designed for operation across 0°C to 70°C ambient, it features on-chip trimming for 1% initial voltage tolerance and achieves 10 mV max reference voltage change over full current range (100 μA to 20 mA). Thermal resistance θ_JA is 440°C/W in TO-92, supporting thermal-aware PCB layout in space-constrained applications.

Key Specifications

Pinout & Package

LM385BZ/NOPB uses a TO-92 package (JEDEC TO-226, variation AA), 5.34 mm max height, with straight or formed leads. Pin 1 = Anode, Pin 2 = Cathode, Pin 3 = Adjust (V_REF tap).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLVH431ACDBVR and LM4040CIM3-ADJ, LM385BZ/NOPB uniquely supports 1.24–5.30 V adjustment with 10 μA operation and through-hole TO-92 mounting-making it optimal for legacy designs, prototyping, and ultra-low-quiescent applications where flexibility and power efficiency are jointly critical.

Availability

LM385BZ/NOPB is available at Aetrix Electronics and suitable for portable instrumentation, battery-powered sensor nodes, low-cost industrial regulators, and programmable threshold detectors requiring stable component supply across production lifecycles.

Supply support for LM385BZ/NOPB 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 power management solutions.

The LM385 series belongs to TI's micropower voltage reference product line, engineered for high-accuracy, low-drift shunt references in battery-operated and space-constrained systems where long-term stability and minimal quiescent current are essential.

FAQ

What is the maximum operating temperature for LM385BZ/NOPB?

The LM385BZ/NOPB is rated for operation from 0°C to 70°C ambient temperature. Its maximum junction temperature is 100°C, and thermal resistance θ_JA is 440°C/W in the TO-92 package. Derating is required above 70°C ambient; sustained operation beyond this range may compromise initial tolerance and long-term stability. Always verify board-level thermal performance when deploying LM385BZ/NOPB in enclosed or high-ambient environments.

Can LM385BZ/NOPB be used as a 2.5 V reference?

Yes, LM385BZ/NOPB can be configured as a precise 2.5 V reference using an external resistor divider between cathode (Pin 2) and adjust (Pin 3), per the formula V_OUT = V_REF(1 + R1/R2). With its 1.24 V nominal reference voltage and 1% initial tolerance, achieving 2.5 V ±0.5% is straightforward. The device's low 25 nA feedback current ensures minimal loading error on the divider, preserving accuracy without buffer amplification.

Does LM385BZ/NOPB require an output capacitor for stability?

No, LM385BZ/NOPB is explicitly designed to be capacitive-load tolerant and remains stable with output capacitance up to at least 1 μF-no series isolation resistor or minimum ESR requirement. This simplifies layout in noise-sensitive applications like precision ADC references. However, a 0.1 μF ceramic capacitor is still recommended near the cathode pin to suppress high-frequency PCB noise, especially in mixed-signal systems sharing ground planes.

What is the minimum current needed to maintain regulation in LM385BZ/NOPB?

The LM385BZ/NOPB requires a minimum operating current of 10 μA to maintain regulation, as specified in the Electrical Characteristics table. Below this, the reference voltage collapses and becomes undefined. In practice, design the bias network to deliver ≥15 μA under worst-case conditions (e.g., lowest input voltage, highest temperature) to ensure margin. At 10 μA, dynamic impedance rises slightly, but voltage accuracy remains within datasheet limits.

How does LM385BZ/NOPB compare to LM385BXZ/NOPB?

LM385BZ/NOPB and LM385BXZ/NOPB share identical TO-92 packaging, 0°C to 70°C temperature range, and 1% initial tolerance-but differ in voltage grade: LM385BZ/NOPB is the "B" grade (1.240–1.270 V nominal reference), while LM385BXZ/NOPB is the "X" grade (1.215–1.245 V). Both offer same dynamic impedance (1 Ω), noise (50 μV_RMS), and operating current range. Select LM385BZ/NOPB when tighter mid-range reference voltage is preferred for 2.5 V or 5.0 V designs.