STMicroelectronics LF33ABV

Overview

LF33ABV from STMicroelectronics is a 3.3 V, ±1% tolerance, automotive-grade low-dropout linear regulator in PPAK-5 package with logic-controlled shutdown, 0.35 V dropout at 500 mA, 500 µA typical quiescent current in ON mode, and stable operation with only 2.2 µF output capacitance - deployed in engine control units for post-ignition rail stabilization.

For engineers reviewing the LF33ABV datasheet, LF33ABV pinout, LF33ABV application, or LF33ABV equivalent, this page delivers verified electrical specs, thermal behavior, shutdown interface timing, stability requirements, and AEC-Q100-compliant use cases - all grounded in ST's DocID2574 Rev 31 production data.

Technical Context

The LF33ABV implements a fixed-output, NPN-based LDO architecture with internal current and thermal limiting, enabling safe operation up to 125 °C junction temperature. Its 5-pin PPAK configuration integrates a TTL-compatible enable input (Pin 2) that drives the regulator into sub-100 µA OFF-mode quiescent current when pulled low.

Stability is achieved with minimal external components: only a 2.2 µF ceramic output capacitor (ESR 0.1–10 Ω) is required across the output, eliminating need for bulk electrolytics. Supply voltage rejection reaches 80 dB at 120 Hz, supporting noise-sensitive analog subsystems in automotive power domains.

Key Specifications

Pinout & Package

LF33ABV is housed in a thermally enhanced PPAK-5 surface-mount package (4.5 × 6 mm, 1 mm height), with exposed thermal pad electrically connected to GND for efficient heat dissipation. Junction-to-case thermal resistance is 8 °C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV73333PDBVR and NCP1117ST33T3G, LF33ABV uniquely combines AEC-Q100 Grade 1 qualification, integrated EN pin, 500 mA capability, and ultra-low 0.35 V dropout - making it the only drop-in solution for automotive LDO applications demanding functional safety alignment and cold-crank resilience.

Availability

LF33ABV is available at Aetrix Electronics and suitable for engine control units, body control modules, ADAS camera ECUs, and infotainment power sequencing requiring stable component supply across automotive production lifecycles.

Supply support for LF33ABV 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, Switzerland, designing and manufacturing silicon solutions for automotive, industrial, and consumer markets since 1987.

LF33ABV belongs to the LFXX family of automotive-qualified LDOs, engineered specifically to replace legacy 78xx regulators in harsh-environment vehicle electronics - emphasizing low dropout, low IQ, and seamless integration into AEC-Q100-compliant power architectures.

FAQ

What is the minimum input voltage required for LF33ABV to maintain regulation at 500 mA?

The minimum input voltage is calculated as V_OUT + V_DROP = 3.3 V + 0.35 V = 3.65 V. At 500 mA load and 25 °C, regulation is guaranteed above this threshold; at 125 °C, worst-case dropout rises to 0.7 V, requiring ≥4.0 V input. Input below 3.65 V causes output collapse.

Can LF33ABV be used without the enable (EN) pin connected?

Yes - leaving EN open or tying it to IN places LF33ABV in permanent ON mode. However, doing so forfeits shutdown capability and increases system standby current by ~450 µA. For automotive applications, EN should be actively driven to ensure controlled power sequencing and low-quiescent operation.

Is an input capacitor mandatory for LF33ABV stability?

While the datasheet specifies CI = 0.1 µF for test conditions, ST recommends a 0.1 µF X7R ceramic capacitor placed within 2 mm of the IN pin to suppress high-frequency noise and prevent oscillation during fast load transients. Omission risks instability under pulsed loads common in MCU-based systems.

Does LF33ABV require a heatsink in PPAK-5 package at 500 mA continuous load?

No external heatsink is required if PCB layout provides ≥200 mm² of 2-oz copper connected to the thermal pad. With R_thJA = 100 °C/W and 500 mA load at 12 V input, power dissipation is ~3.35 W, raising junction temperature by ~335 °C above ambient - which exceeds rating. Derating to ≤300 mA or enhancing copper area is mandatory for sustained operation.