Texas Instruments LM334SMX/NOPB

Overview

LM334SMX/NOPB from Texas Instruments is a 3-terminal adjustable current source optimized for 0°C to +70°C operation, delivering programmable output from 1 μA to 10 mA with ±3% initial accuracy, 0.02%/V current regulation, and true 2-terminal operation. It serves as a precision bias generator, temperature sensor, or LED driver in low-power analog circuits requiring stable current over wide voltage (1–40 V) and temperature ranges.

For engineers reviewing the LM334SMX/NOPB datasheet, LM334SMX/NOPB pinout, LM334SMX/NOPB application, or LM334SMX/NOPB equivalent, key selection considerations include its 67.7 mV reference voltage at 25°C, +0.336%/°C temperature coefficient, SOIC-8 package thermal resistance (θ_JA = 165°C/W), and compatibility with remote temperature sensing via Kelvin-proportional current output.

Technical Context

The LM334SMX/NOPB operates as a floating two-terminal current source where output current I_SET is set by an external resistor R_SET using the relationship I_SET = 67.7 mV / R_SET at 25°C, with inherent +0.336%/°C drift due to absolute temperature dependence. Its internal architecture eliminates need for separate power rails and supports reverse voltage tolerance up to 20 V.

It achieves zero-drift operation when augmented with one diode and resistor to cancel temperature coefficient, and exhibits 15 pF shunt capacitance that impacts AC output impedance-addressable via FET buffering. Minimum operating voltage ranges from 0.8 V (at 2 μA) to 1.0 V (at 5 mA), enabling micropower applications.

Key Specifications

Pinout & Package

LM334SMX/NOPB is housed in an SOIC-8 plastic package (Package Drawing D), 3.91 mm × 4.90 mm × 1.75 mm, with standard JEDEC MS-012AA footprint and RoHS-compliant Sn lead finish. Thermal resistance θ_JA = 165°C/W enables operation up to +70°C ambient without heatsinking under typical loads.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar adjustable current source applications.

Compared with LM334Z/NOPB, LM334SMX/NOPB offers better thermal dissipation in SOIC-8 and tighter layout control; compared with REF200AU, it trades fixed-accuracy stability for full 1 μA–10 mA programmability and lower unit cost in single-source applications.

Availability

LM334SMX/NOPB is available at Aetrix Electronics and suitable for industrial sensor interfaces, LED lighting controls, and precision analog biasing requiring stable component supply across extended production lifecycles.

Supply support for LM334SMX/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 leader specializing in analog and embedded processing technologies, with decades of leadership in precision analog ICs and industrial-grade reliability.

The LM334 family was designed specifically for applications demanding stable, temperature-aware current sources - including remote sensing, micropower references, and programmable bias networks in harsh or space-constrained environments.

FAQ

What is the reference voltage used by LM334SMX/NOPB to set output current?

The LM334SMX/NOPB uses a 67.7 mV reference voltage at 25°C across its V+ and V− terminals to establish output current. This voltage appears across the external R_SET resistor connected between V− and the R pin, yielding I_SET = 67.7 mV / R_SET. The value increases linearly with absolute temperature (°K), maintaining proportionality across the 0°C to +70°C operating range of the LM334SMX/NOPB.

Can LM334SMX/NOPB operate as a true 2-terminal device?

Yes, LM334SMX/NOPB supports true 2-terminal operation: connect V+ to the positive supply and V− to the load return, with R pin tied to V−. In this configuration, it functions as a floating current source drawing current from the supply and delivering it through the load - no ground reference or additional supply connections required. This mode is explicitly validated in TI's Figure 21 (Basic 2-Terminal Current Source) for LM334SMX/NOPB.

What is the maximum operating temperature for LM334SMX/NOPB?

The LM334SMX/NOPB is rated for operation from 0°C to +70°C ambient temperature. Its junction temperature limit is 100°C, and with θ_JA = 165°C/W in SOIC-8, it can safely dissipate up to ~60 mW at +70°C ambient. For example, at 5 mA output and 10 V across the device (50 mW), junction temperature rises ~8.25°C above ambient - well within safe margin for LM334SMX/NOPB.

How does LM334SMX/NOPB enable remote temperature measurement?

LM334SMX/NOPB outputs current directly proportional to absolute temperature (I_SET ∝ T in °K), making it ideal for 2-wire remote sensing. Since current - not voltage - is transmitted, lead resistance has no effect on accuracy. At 25°C (298.15 K), LM334SMX/NOPB delivers ≈298 μA with appropriate R_SET; scaling is linear, so 0°C yields 0 μA (theoretical) and 70°C yields ≈343 μA - enabling direct Kelvin readout with minimal signal conditioning.

Is LM334SMX/NOPB RoHS compliant and lead-free?

Yes, LM334SMX/NOPB is RoHS compliant and features a lead-free Sn (tin) lead finish, as confirmed in TI's PACKAGE OPTION ADDENDUM. It carries the "/NOPB" suffix denoting lead-free packaging, meets JEDEC MSL Level-1 moisture sensitivity requirements, and is qualified for reflow soldering at 260°C peak per JEDEC J-STD-020. All LM334SMX/NOPB units shipped by Aetrix Electronics meet current RoHS Directive 2011/65/EU standards.