STMicroelectronics LF18CV

Overview

LF18CV from STMicroelectronics is a very low dropout (LDO) linear voltage regulator delivering 1.8 V at up to 500 mA output current, with 0.7 V dropout at 200 mA, ±2% output voltage accuracy (C grade), and logic-controlled shutdown (TTL-compatible enable pin). It operates from 3 V to 16 V input, supports -40°C to +125°C junction temperature, and requires only a 2.2 µF ceramic output capacitor for stability - making it suitable for space-constrained, battery-powered microcontroller core supplies.

For engineers reviewing the LF18CV datasheet, LF18CV pinout, LF18CV application, or LF18CV equivalent, key selection considerations include its 0.7 V dropout at 200 mA, 50 µA quiescent current in OFF mode, ±2% output tolerance over temperature, shutdown control interface, and thermal performance in TO-220FP package.

Technical Context

The LF18CV implements a PNP pass transistor architecture enabling ultra-low dropout operation and high PSRR (82 dB at 120 Hz). Its internal current and thermal limiting protect against fault conditions without external components.

It features a dedicated TTL-compatible enable input (pin 2 in 5-pin configurations) that places the regulator in ultra-low-current shutdown (50 µA typ.) when pulled low, allowing system-level power sequencing and standby mode control in portable electronics.

Key Specifications

Pinout & Package

LF18CV is packaged in TO-220FP (5-pin, vertical mount, isolated tab), with pin 1 = Input, pin 2 = Enable (TTL-compatible), pin 3 = Ground, pin 4 = Output, pin 5 = Tab (Ground).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LD1117S18TR and TPS7A0518PDBVR, LF18CV uniquely balances 500 mA output, 0.7 V dropout, integrated enable, and TO-220FP thermal performance - making it optimal for medium-power, thermally demanding, and system-controlled LDO applications.

Availability

LF18CV is available at Aetrix Electronics and suitable for industrial PLC I/O modules, automotive body control units, portable medical sensor nodes, and Wi-Fi 6 IoT gateway baseband designs requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LF18CV 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, designing and manufacturing analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The LF00 series was developed specifically for low-noise, low-power, battery-sensitive applications requiring high accuracy, ultra-low dropout, and logic-controlled shutdown - targeting portable electronics, automotive subsystems, and industrial edge devices.

FAQ

What is the minimum input voltage required for stable 1.8 V output at 500 mA?

The LF18CV requires a minimum input voltage of 2.5 V to maintain regulation at 500 mA load, based on its maximum dropout specification of 0.7 V at 200 mA and typical behavior scaling to ~0.8 V at full load. For guaranteed 1.8 V output under all conditions including temperature and tolerance extremes, 3.0 V input is recommended per datasheet test conditions.

Can LF18CV be used without the enable pin connected?

Yes - the enable pin (pin 2) is active-high and internally pulled up in most implementations; leaving it open or connecting it to VIN ensures continuous operation. However, ST's official recommendation is to tie it directly to VIN or use an external pull-up to avoid noise-induced shutdown. Floating is not advised in noisy environments.

Is a heatsink required for 500 mA operation at 125°C ambient?

Yes - with R_thJA = 60°C/W (TO-220FP), dissipating 0.8 V × 0.5 A = 0.4 W raises junction temperature by 24°C above ambient. At 125°C ambient, T_J reaches 149°C, exceeding the 125°C absolute maximum. A small heatsink (≤10°C/W) or ≥5 cm² copper pour is required to maintain safe operation.

Does LF18CV support ceramic output capacitors with ESR below 0.1 Ω?

No - the datasheet specifies stable operation only with output capacitors having ESR between 0.1 Ω and 10 Ω. Ultra-low-ESR ceramics (<0.05 Ω) may cause oscillation due to insufficient phase margin; a 1–5 Ω damping resistor in series with the capacitor restores stability if low-ESR types must be used.