STMicroelectronics LF18ABV

Overview

LF18ABV from STMicroelectronics is a 1.8 V fixed-output, very low dropout (LDO) linear regulator in PENTAWATT-5 package with logic-controlled shutdown, delivering up to 500 mA output current, 0.7 V dropout at 200 mA, ±1% output voltage accuracy at 25°C, and 50 µA quiescent current in OFF mode. It serves as a local power supply for microcontroller core rails in battery-powered portable instrumentation.

For engineers reviewing the LF18ABV datasheet, LF18ABV pinout, LF18ABV application, or LF18ABV equivalent, key selection criteria include dropout voltage under load, shutdown logic compatibility (TTL), thermal resistance (R_thJC = 3°C/W), stability with 2.2 µF ceramic output capacitor, and operation across –40°C to +125°C junction temperature.

Technical Context

The LF18ABV implements a PNP pass transistor architecture enabling ultra-low dropout performance and high PSRR (82 dB at 120 Hz). Its internal circuit integrates thermal shutdown, current limiting, and a dedicated TTL-compatible control input (pin 2) that enables system-level power sequencing and standby mode activation.

It operates with a minimum input voltage of 3.0 V (for 500 mA load) and supports full-rated output current across its –40°C to +125°C operating junction temperature range. The device achieves stable regulation using only a 2.2 µF output capacitor with ESR between 0.1 Ω and 10 Ω-eliminating need for electrolytic or tantalum types.

Key Specifications

Pinout & Package

PENTAWATT-5 (vertical mount, 5-pin) package with exposed tab for thermal dissipation; R_thJC = 3°C/W enables >3 W power handling with minimal heatsinking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LD1117S18TR and TPS7A0518PDQNR, LF18ABV uniquely balances 500 mA capability, 0.7 V dropout, TTL-compatible shutdown, and ±1% accuracy in a thermally robust PENTAWATT-5 package-making it optimal for automotive and industrial LDO applications demanding both performance and ruggedness.

Availability

LF18ABV is available at Aetrix Electronics and suitable for portable medical sensors, automotive body control modules, and industrial IoT edge nodes requiring stable component supply with long-term lifecycle support.

Supply support for LF18ABV 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 ICs with ISO/TS 16949-certified manufacturing.

The LF00 series was designed specifically for low-noise, low-power, battery-critical applications-emphasizing ultra-low dropout, micropower shutdown, and wide-temperature operation in automotive and industrial settings.

FAQ

What is the minimum input voltage required for LF18ABV to deliver 500 mA output?

The LF18ABV requires a minimum input voltage of 3.0 V to sustain 500 mA output current while maintaining regulation, based on its 0.7 V dropout at 200 mA and derated performance at full load. At 500 mA, dropout increases to ≤0.7 V per datasheet Table 5, confirming 3.0 V input is sufficient for 1.8 V output.

Can LF18ABV operate without the BYP (pin 5) capacitor?

No. The 0.1 µF ceramic capacitor on pin 5 (BYP) is mandatory for internal bias stability and transient response. Omitting it causes output oscillation or regulation failure, as confirmed in the "Test circuits" footnote of Table 5 and Figure 2 schematic in the official datasheet.

Is LF18ABV pin-compatible with other LF00-series variants like LF33ABV?

No. While all PENTAWATT-5 LF00 devices share identical pinout (IN, SHDN, GND, OUT, BYP), output voltage is laser-trimmed during production and not interchangeable. LF18ABV delivers 1.8 V; substituting LF33ABV (3.3 V) would overvoltage downstream 1.8 V logic, causing immediate damage.

Does LF18ABV require a heatsink in a typical PCB layout?

Not under typical conditions. With R_thJC = 3°C/W and R_thJA = 50°C/W, the PENTAWATT-5 package dissipates up to ~1.5 W without external heatsink at 25°C ambient. For 500 mA at 3.0 V input (1.2 V drop = 0.6 W), junction temperature rise is ~30°C-well within the 125°C limit. Thermal relief pads and 2+ oz copper on GND layer are recommended for sustained loads.