Analog Devices Inc. LT1965ET-1.8#PBF

Overview

LT1965ET-1.8#PBF from Analog Devices (formerly Linear Technology) is a fixed-output, low-noise, low-dropout linear regulator delivering 1.1A at 1.8V with 310mV typical dropout voltage, 40µV_RMS output noise (10Hz–100kHz), and <1µA shutdown quiescent current - designed for powering sensitive RF and DSP circuitry in portable instrumentation and post-regulation of switching supplies.

For engineers reviewing the LT1965ET-1.8#PBF datasheet, LT1965ET-1.8#PBF pinout, LT1965ET-1.8#PBF application, or LT1965ET-1.8#PBF equivalent, this page provides verified package mapping (TO-220, 5-lead), thermal performance data (θ_JA = 50°C/W), reverse-battery protection, stable operation with 10µF ceramic/tantalum output capacitors, and confirmed fixed 1.8V output accuracy (±1.5% over temperature).

Technical Context

The LT1965ET-1.8#PBF employs a PNP pass transistor architecture enabling low dropout and tightly controlled quiescent current that remains stable in dropout - unlike many LDOs where I_Q rises under dropout conditions. Its error amplifier uses the SENSE pin (Pin 5) as the feedback reference input, allowing Kelvin sensing for precision regulation at the load.

Internal protection includes reverse-battery protection (no external diode required), foldback current limiting, thermal shutdown at 150°C, and reverse-current blocking. The device operates across a 2.8V to 20V input range and maintains regulation down to 1.8V output with ≤24mV load regulation (1mA–1.1A) and ≤11.5mV line regulation (2.8V–20V).

Key Specifications

Pinout & Package

LT1965ET-1.8#PBF is housed in a 5-lead plastic TO-220 package (T-package) with exposed tab connected to GND. Thermal resistance is θ_JA = 50°C/W and θ_JC = 3°C/W. The tab must be soldered to PCB copper for optimal thermal performance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-noise LDO regulator applications.

Compared with LT1965ET-1.8#PBF, LT3045EDD#PBF trades 60% lower noise for 55% less current and no reverse-battery capability, while TPS7A4701RGWR offers superior noise and adjustability but requires external protection and has inferior thermal performance in high-ambient environments.

Availability

LT1965ET-1.8#PBF is available at Aetrix Electronics and suitable for portable medical devices, industrial PLCs, RF communication modules, and battery-powered test equipment requiring stable component supply with guaranteed long-term availability and full traceability.

Supply support for LT1965ET-1.8#PBF 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, datasheets, and application engineering for the LT1965 series. Linear was renowned for high-performance analog ICs with rigorous characterization.

The LT1965 series was designed specifically for noise-sensitive power domains in RF, instrumentation, and portable systems - emphasizing ultra-low output noise, robust protection features, and stable operation with modern ceramic capacitors.

FAQ

What is the maximum input voltage rating for the LT1965ET-1.8#PBF?

The LT1965ET-1.8#PBF has an absolute maximum input voltage of ±22V on the IN pin, but its functional operating range is 2.8V to 20V. Exceeding 20V risks violating the input-to-output differential limit (±22V) and may trigger internal protection. For reliable operation, keep VIN ≤20V and maintain VIN – VOUT ≤18.2V per datasheet Note 2.

Does the LT1965ET-1.8#PBF require an external capacitor on the SENSE pin?

No - the LT1965ET-1.8#PBF does not require an external capacitor on the SENSE pin. The SENSE pin (Pin 3) is internally connected to the error amplifier's inverting input and is designed to be tied directly to the OUT pin (standard configuration) or to the remote load point (Kelvin sensing). Adding capacitance here would degrade transient response and is not recommended per the datasheet Applications Information section.

Can the LT1965ET-1.8#PBF be used with a 10µF X5R ceramic capacitor for stability?

Yes - the LT1965ET-1.8#PBF is explicitly characterized and guaranteed stable with 10µF ceramic (X5R/X7R) or tantalum output capacitors, as stated in the Features and Electrical Characteristics sections. Unlike older LDOs, it does not require minimum ESR, making 10µF X5R MLCCs fully compliant and optimal for space-constrained, high-reliability designs.

What is the thermal performance of the LT1965ET-1.8#PBF in TO-220 package at 1.1A load?

In the TO-220 package, the LT1965ET-1.8#PBF has θ_JA = 50°C/W and θ_JC = 3°C/W. At 1.1A and 310mV dropout (0.34W dissipation), junction temperature rise above ambient is ~17°C with proper heatsinking. Without heatsink, ambient must stay ≤85°C to keep T_J ≤125°C - verified by the "Typical Dropout Voltage" and "Quiescent Current vs Temperature" curves in the datasheet.

How does the shutdown function behave on the LT1965ET-1.8#PBF?

The SHDN pin (Pin 5) is active-low: pulling it ≤0.45V disables the output and reduces quiescent current to <1µA; raising it ≥0.85V enables regulation. The pin draws <5.5µA when high and tolerates voltages up to 20V. If unused, tie SHDN to VIN - never leave it floating, as leakage could cause erratic enable/disable behavior in the LT1965ET-1.8#PBF.