STMicroelectronics LF33CV-DG

Overview

LF33CV-DG from STMicroelectronics is a 3.3 V, 500 mA very low-dropout linear regulator with logic-controlled shutdown (TTL-compatible inhibit), ±1% output voltage accuracy at 25 °C, 0.4 V dropout at 500 mA, and operation from −40 to 125 °C. It delivers stable local power in automotive body control modules, industrial PLC I/O stages, and battery-backed sensor nodes where low quiescent current (50 µA in OFF mode) and minimal external capacitance (2.2 µF) are critical.

For engineers reviewing the LF33CV-DG datasheet, LF33CV-DG pinout, LF33CV-DG application, or LF33CV-DG equivalent, key selection criteria include its AEC-Q100 qualified DPAK package, 80 dB supply rejection at 120 Hz, internal thermal/current limiting, and compatibility with low-ESR ceramic output capacitors in space-constrained designs.

Technical Context

The LF33CV-DG implements a PNP-based LDO architecture with integrated bandgap reference, error amplifier, and pass transistor-enabling ultra-low dropout (0.2–0.7 V across load/temperature) and high PSRR without external compensation. Its 5-pin DPAK configuration includes dedicated INH (inhibit) and GND pins, allowing precise system-level power sequencing via TTL-level control signals.

Thermal protection activates at junction temperatures exceeding 160 °C, and current limiting holds output short-circuit current to ~1 A. The device maintains regulation down to VI = VO + Vd, with input voltage range of 4.3–16 V and guaranteed stability using only a 2.2 µF ceramic capacitor (ESR 0.1–10 Ω).

Key Specifications

Pinout & Package

LF33CV-DG uses the DPAK (TO-252-3) surface-mount package with exposed thermal pad electrically connected to GND. Pin 1 = Input (IN), Pin 2 = Ground (GND), Pin 3 = Output (OUT), Pin 4 = Inhibit (INH), Pin 5 = Ground (GND). TAB is internally tied to Pin 2 and Pin 5 for enhanced thermal dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LDL1133PU33R and TPS78033QDRVRQ1, LF33CV-DG uniquely balances AEC-Q100 qualification, 500 mA drive, 0.4 V dropout from 12 V input, and 50 µA shutdown-making it the only choice for thermally demanding, high-current automotive LDO applications requiring full-grade reliability.

Availability

LF33CV-DG is available at Aetrix Electronics and suitable for automotive body electronics, industrial PLC I/O modules, and battery-powered sensor nodes requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LF33CV-DG 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 microcontrollers, power management ICs, sensors, and automotive-grade components.

LF33CV-DG belongs to the LFXX family of very low-dropout regulators engineered specifically for automotive and industrial applications demanding AEC-Q100 compliance, wide temperature operation, and robust transient performance.

FAQ

What is the minimum input voltage required for regulation at full 500 mA load?

The LF33CV-DG requires VI ≥ VO + Vd = 3.3 V + 0.4 V = 3.7 V to maintain regulation at 500 mA. However, per datasheet Table 11, the specified operating input voltage starts at 4.3 V to guarantee all electrical characteristics-including line/load regulation and PSRR-across temperature and process variation.

Can the INH pin be left floating, or does it require a pull-up/down resistor?

The INH pin must not be left floating. It has no internal pull-up or pull-down. To ensure reliable ON operation, tie INH to VIN through a 10–100 kΩ resistor. For automatic shutdown on power-up, connect INH to a controlled GPIO or open-drain driver referenced to GND.

Is the thermal pad on the DPAK package electrically isolated or connected to GND?

The thermal pad on LF33CV-DG's DPAK package is electrically connected to GND (Pins 2 and 5). It must be soldered to a large GND copper pour for thermal performance and electrical integrity-no insulation or isolation is required or recommended.

Does LF33CV-DG support ceramic output capacitors with ESR below 0.1 Ω?

No. The datasheet specifies CO = 2.2 µF with ESR between 0.1 Ω and 10 Ω for guaranteed stability. Ceramic capacitors with ESR < 0.1 Ω (e.g., standard X7R/X5R) may cause oscillation; use ESR-specified ceramics or add a 0.1–1 Ω series resistor if ultra-low-ESR caps are mandatory.