STMicroelectronics L4949EP-E

Overview

L4949EP-E from STMicroelectronics is an AEC-Q100 qualified automotive 5 V very low dropout linear voltage regulator with integrated power-on reset, input voltage sense comparator, and preregulator output (VZ). It delivers up to 100 mA output current with dropout voltage < 0.5 V at 100 mA, quiescent current ≤ 300 µA, and standby output accuracy of 5 V ±1%, designed for microcontroller power supply in engine control units and body electronics.

For engineers reviewing the L4949EP-E datasheet, L4949EP-E pinout, L4949EP-E application, or L4949EP-E equivalent, key selection criteria include its 40 V transient tolerance, programmable reset delay via external capacitor, sense comparator with 1.23 V threshold, and SO-20W package thermal resistance of 50 °C/W - critical for under-hood reliability and ECU power sequencing.

Technical Context

The L4949EP-E integrates a PNP-based low-dropout regulator core with three auxiliary functional blocks: a voltage-sense comparator referenced to 1.23 V (±100 mV hysteresis), a reset circuit triggered at VO ≤ 4.5 V with externally adjustable delay (55–180 ms for CT = 100 nF), and a 5 V preregulator output (VZ) capable of sourcing ≤10 µA for internal bias stabilization.

Its SO-20W (12+4+4) package provides dedicated ground pins (pins 4,5,6,7,14,15,16,17) and isolated sense/reset outputs (SI, RES, SO), enabling robust noise immunity in automotive 12 V/24 V systems where supply transients exceed 100 V/µs above 8 V input - while maintaining regulated 5 V output down to VS = 3 V in dropout mode.

Key Specifications

Pinout & Package

The L4949EP-E is housed in a SO-20W (12+4+4) thermally enhanced surface-mount package with 20 leads, featuring 8 dedicated GND pins for low-impedance return paths and separate power/signal routing zones to minimize noise coupling.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV73350PDBVR and MAX16910ATA+, the L4949EP-E uniquely combines AEC-Q100 Grade 0 operation, SO-20W thermal performance, and three integrated supervisory functions (reset, sense, preregulator) - making it the only choice for high-reliability ECU power domains requiring coordinated fault detection and thermal resilience.

Availability

L4949EP-E 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 L4949EP-E 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, specializing in automotive, industrial, and power management ICs with broad manufacturing and quality certification coverage.

The L4949EP-E belongs to ST's automotive-grade linear regulator product line, engineered specifically for microcontroller power supply in harsh-temperature, high-transient automotive environments - emphasizing functional safety readiness, long-term supply stability, and integrated system-level supervision.

FAQ

What is the maximum allowable input voltage for continuous operation?

The L4949EP-E supports continuous DC input voltage from 5 V to 28 V. Its absolute maximum rating allows transient exposure up to 40 V for durations under 1 second, complying with ISO 7637-2 load-dump test requirements. Operation above 28 V beyond 1 s risks permanent damage due to exceeding junction temperature limits or internal overstress.

Can the VZ pin be used as a secondary 5 V output?

No - the VZ pin is a preregulator output intended solely for internal bias stabilization and transient immunity enhancement. It is rated for ≤10 µA load current and lacks output regulation or protection circuitry. Using it as a power source may cause instability, inaccurate reset timing, or premature thermal shutdown under load.

How does the sense comparator interface with a microcontroller?

The SO pin is an open-collector output that pulls low when the SI voltage falls below 1.16 V. It requires an external pull-up resistor (typically 10 kΩ) to VOUT. The MCU monitors SO as an interrupt or GPIO input to detect input undervoltage conditions - e.g., battery sag below 9 V using a 2:1 resistor divider on SI.

Is the SO-20W package footprint compatible with SO-8 layouts?

No - the SO-20W (12+4+4) package has 20 leads, 13.0 mm × 7.5 mm body size, and 1.27 mm pitch, whereas SO-8 measures 4.9 mm × 6.0 mm with 1.27 mm pitch and only 8 leads. They are mechanically and electrically incompatible; PCB redesign is required to migrate from L4949ED-E (SO-8) to L4949EP-E (SO-20W).