Analog Devices Inc. LT3092IST

Overview

LT3092IST from Analog Devices (formerly Linear Technology) is a 2-terminal programmable current source IC in SOT-223 package, delivering 0.5mA–200mA output with ±1% initial SET pin current accuracy, <0.001%/V line regulation, and 1.2V–40V input voltage range. It operates without input/output capacitors and is used in intrinsic safety circuits, remote sensor excitation, and precision current limiting.

For engineers reviewing the LT3092IST datasheet, LT3092IST pinout, LT3092IST application, or LT3092IST equivalent, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, confirmed application use cases, and two rigorously cross-checked alternative parts for current-source designs requiring high DC/AC impedance and reverse-voltage protection.

Technical Context

The LT3092IST implements a precision 10µA reference current source feeding the noninverting input of a power operational amplifier, enabling Kelvin-sensed current regulation with <10ppm/V compliance over 1.5V–40V input-to-output differential. Its architecture eliminates need for bypass capacitors by achieving high DC impedance (>1GΩ) and AC impedance (>10MΩ at 100kHz).

Internal protection includes reverse-battery protection (±40V IN-to-SET/OUT), reverse-current blocking, thermal shutdown with hysteresis, and current limiting up to 300mA. The device maintains regulation down to 0.5mA load and supports floating or ground-referred configurations via its 2-terminal topology.

Key Specifications

Pinout & Package

LT3092IST uses the 3-lead plastic SOT-223 package (ST package), where the tab is internally connected to OUT and must be soldered to the PCB's OUT net for thermal and electrical integrity. Pin 1 = SET, Pin 2 = OUT, Pin 3 = IN.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 2-terminal current source applications.

Compared with LT3092IST, LT3092ETS8#TRPBF trades thermal capability for footprint reduction, while LT3092EDD#TRPBF delivers superior thermal management at the cost of larger PCB area and assembly complexity-both retain identical electrical behavior and pin-compatible functionality within their respective packages.

Availability

LT3092IST is available at Aetrix Electronics and suitable for loop-powered transmitters, remote sensor excitation, precision current limiting, and intrinsically safe barrier circuits requiring stable component supply across industrial, oil & gas, and process automation programs.

Supply support for LT3092IST 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

Analog Devices acquired Linear Technology in 2017 and maintains full product support, manufacturing, and documentation for the LT® family of precision analog ICs.

The LT3092IST belongs to Linear Technology's precision current source product line, engineered specifically for applications demanding capacitor-free stability, reverse-protection, and intrinsic safety compliance in harsh industrial environments.

FAQ

What is the minimum load current required for LT3092IST to regulate properly?

The LT3092IST requires a minimum load current of 0.5mA to maintain regulation. Below this threshold, the internal error amplifier cannot sustain closed-loop control, causing output current to collapse. This value is specified in the Electrical Characteristics table under "Minimum Load Current" and is independent of input voltage across the 1.2V–40V range. Designers must ensure the connected load or parallel leakage paths draw at least 0.5mA under all operating conditions.

Can LT3092IST operate without any external capacitors?

Yes, the LT3092IST is explicitly designed to operate stably without input or output capacitors, a key feature enabling intrinsic safety compliance. Its high DC and AC output impedance eliminates phase-shift risks associated with capacitive loading. However, adding a capacitor across R_SET reduces noise but introduces a pole requiring external compensation (e.g., series RC network) to maintain stability-details are in the Applications Information section of the LT3092IST datasheet.

How does the SET pin current accuracy affect LT3092IST output current precision?

The LT3092IST's SET pin delivers a nominal 10µA current with ±1% initial accuracy at 25°C. Since output current is calculated as I_OUT = 10µA × R_SET/R_OUT, this tolerance directly propagates to the programmed current. For example, a 1% error in SET current yields a 1% error in I_OUT, assuming ideal resistors. Temperature drift adds ±0.003%/°C typical, so over –40°C to 125°C, total error remains within ±2.5% for most applications.

What is the purpose of the exposed tab on the LT3092IST SOT-223 package?

The exposed tab on the LT3092IST SOT-223 package is electrically and thermally connected to the OUT pin. It must be soldered directly to the PCB's OUT net to provide low-thermal-resistance heat dissipation (θ_JA = 24°C/W) and ensure proper current return path. Leaving it unconnected degrades thermal performance by >40°C/W and may cause thermal shutdown under 100mA loads. The tab is not a separate ground or heatsink terminal-it is OUT.

Does LT3092IST support paralleling for higher output current?

Yes, the LT3092IST supports paralleling to achieve output currents beyond 200mA. Two recommended methods exist: (1) Tie IN and OUT pins together across devices (simple but less current sharing), or (2) tie SET and IN pins together while using matched PCB trace ballast resistors (e.g., 40mΩ) on each OUT path for >80% current sharing at 200mA per device. Both methods preserve the 2-terminal architecture and require no additional control logic.