STMicroelectronics LF15CDT

Overview

LF15CDT from STMicroelectronics is a 1.5 V fixed-output, 500 mA very low dropout (LDO) linear regulator in TO-220FP package with logic-controlled shutdown (TTL-compatible enable pin), ±2% output voltage accuracy at 25°C, 0.45 V typical dropout at 200 mA, and 50 µA quiescent current in OFF mode. It serves as a local power supply for microcontroller core rails and low-power sensor subsystems in battery-operated industrial telemetry nodes.

For engineers reviewing the LF15CDT datasheet, LF15CDT pinout, LF15CDT application, or LF15CDT equivalent, key selection considerations include its 1.5 V output stability under 500 mA load, shutdown control timing compatibility with 3.3 V logic, thermal performance in TO-220FP (R_thJA = 60°C/W), and minimal 2.2 µF ceramic output capacitance requirement for stability.

Technical Context

The LF15CDT implements a PNP pass transistor architecture enabling ultra-low dropout voltage (0.45 V typ. at 200 mA) and high PSRR (82 dB at 120 Hz). Its internal bandgap reference and error amplifier maintain ±2% output accuracy across -40 to 125°C junction temperature range.

Shutdown is controlled via Pin 2 (INH), which accepts TTL-level inputs (V_IL ≤ 0.8 V, V_IH ≥ 2 V) and draws only 10 µA input current. The device integrates thermal shutdown and current limiting, with no external components required beyond input/output capacitors.

Key Specifications

Pinout & Package

LF15CDT uses the TO-220FP (Full Pack) 5-pin package with heat sink tab (Pin 3), offering improved thermal resistance (R_thJA = 60°C/W) versus standard TO-220. Pin 1 = Input, Pin 2 = Inhibit (TTL enable), Pin 3 = Ground/Tab, Pin 4 = Output, Pin 5 = Bypass (not connected in standard configuration).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LD1117S15TR and TPS7A2015PDBVR, LF15CDT uniquely balances 500 mA capability, TTL shutdown, TO-220FP thermal performance, and 0.45 V dropout-making it optimal for thermally demanding, battery-sensitive 1.5 V systems requiring active power gating.

Availability

LF15CDT is available at Aetrix Electronics and suitable for industrial sensor nodes, portable medical monitors, automotive body control modules, and smart energy meters requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LF15CDT 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, specializing in power management, microcontrollers, and automotive-grade analog ICs.

The LF00 series was designed specifically for low-noise, low-power embedded systems requiring high accuracy, wide input range, and logic-controlled power sequencing-targeting battery-powered and thermally constrained applications.

FAQ

What is the minimum input voltage required for LF15CDT to regulate 1.5 V at 500 mA?

The minimum input voltage is 2.5 V, as specified in the Absolute Maximum Ratings table. At 500 mA load, the dropout voltage rises to 0.7 V (max), so VI must be ≥ 2.2 V; however, the device guarantees regulation only above 2.5 V input per electrical characteristics tables and thermal derating constraints.

Can LF15CDT be used without connecting Pin 2 (Inhibit)?

Yes-leaving Pin 2 open or tying it to VI (via pull-up) forces the device into permanent ON state. However, doing so forfeits shutdown capability and increases quiescent current to 500 µA instead of 50 µA in OFF mode, impacting battery life in sleep-sensitive applications.

Is a heatsink required for continuous 500 mA operation in TO-220FP package?

A PCB copper pour connected to Pin 3 (tab) is mandatory. With 5 cm² of 2-oz copper on top/bottom layers, thermal simulation shows junction temperature rise of ~45°C at 500 mA and 25°C ambient-well within the -40 to 125°C rating. No additional extruded heatsink is needed for most industrial applications.

Does LF15CDT require an input capacitor, and what value is recommended?

Yes-an input bypass capacitor is required for stability and transient response. STMicroelectronics specifies 0.1 µF ceramic (X7R or better) placed within 5 mm of Pins 1 and 3. Larger values (e.g., 10 µF tantalum) may be added in parallel for bulk filtering but are not necessary for basic regulation.