STMicroelectronics L4949EPTR-E

Overview

L4949EPTR-E from STMicroelectronics is an AEC-Q100-qualified automotive multifunction 5 V very low-dropout linear voltage regulator in SO-20W package, delivering up to 100 mA output current with dropout voltage < 0.5 V at 100 mA, ±1% standby output voltage accuracy, and integrated power-on reset with programmable delay via external capacitor. It supplies microcontroller subsystems in engine control units and body electronics where transient immunity to 40 V/1 s and quiescent current < 300 µA are critical.

For engineers reviewing the L4949EPTR-E datasheet, L4949EPTR-E pinout, L4949EPTR-E application, or L4949EPTR-E equivalent, key selection criteria include its dual-supervision capability (output reset + input sense comparator), preregulator output (VZ) for enhanced transient immunity below 8 V, thermal shutdown, short-circuit protection, and SO-20W footprint compatibility with automotive ECU layout constraints.

Technical Context

The device integrates a PNP-based LDO regulator core with a dedicated reset circuit that monitors VOUT against a 4.5 V threshold (VRT = VO − 0.5 V) and generates a programmable delay (55–180 ms with 100 nF CT) before asserting open-drain RES. Its sense comparator references a 1.23 V internal bandgap and accepts externally divided VS on SI pin to enable flexible undervoltage warning logic.

A separate preregulator stage stabilizes internal bias rails at ~5 V on VZ pin (max 10 µA sink/source), improving noise rejection and transient response-especially under sub-8 V supply conditions-while requiring no external load if unused. All protection functions (thermal shutdown at 165 °C, foldback current limiting, short-circuit foldback) operate autonomously without host intervention.

Key Specifications

Pinout & Package

SO-20W (12+4+4) thermally enhanced surface-mount package with exposed thermal pad; 20-pin layout optimized for automotive PCB thermal management and EMI robustness.

Key Features

Applications

Equivalent & Alternatives

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

Compared with NCP1117ST50T3G and TLE42754G, the L4949EPTR-E uniquely combines 100 mA output, dual supervision (reset + sense), and SO-20W thermal performance in a single AEC-Q100 qualified device-making it optimal for space-constrained, function-integrated automotive modules requiring layered fault detection.

Availability

L4949EPTR-E is available at Aetrix Electronics and suitable for engine control units, body control modules, transmission control units, and ADAS camera ECUs requiring stable component supply with automotive-grade reliability and traceable sourcing.

Supply support for L4949EPTR-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, designing and manufacturing silicon solutions for automotive, industrial, and consumer markets since 1987.

The L4949EPTR-E belongs to ST's automotive power management portfolio, engineered specifically to replace discrete reset + LDO + supervisor combinations in microcontroller-based systems while meeting stringent AEC-Q100 and ISO 16750 requirements.

FAQ

What is the maximum allowable input voltage for continuous operation?

The L4949EPTR-E supports continuous DC input voltage from 5 V to 28 V. It tolerates transient overvoltage up to 40 V for durations ≤1 second without damage or functional interruption, as specified in Table 3 of DS6614 Rev 4. Operation outside this range risks permanent damage to internal PNP pass transistor and protection circuits.

How does the sense comparator function, and what external components are required?

The SI pin connects to a resistor divider from VS to GND, scaling input voltage to match the internal 1.23 V reference. When SI falls below 1.16–1.35 V, the open-collector SO pin pulls low. No external active components are needed-only two resistors defining the division ratio and a pull-up resistor from SO to VOUT per Figure 3.

Can the VZ pin be used as a secondary regulated output?

No-VZ is a preregulator output intended solely for internal bias stabilization. Its output current capability is limited to ≤10 µA (Table 8), and loading it degrades transient immunity and may cause regulation failure. ST explicitly states in Section 3.4 that VZ "should not be used as an output" and must be left open unless adding a 100 nF–1 µF capacitor for noise reduction.

What is the minimum recommended output capacitance, and why is ESR important?

The datasheet mandates CO ≥ 4.7 µF with ESR < 10 Ω at 10 kHz (Figure 3 note). Lower ESR improves transient response and prevents oscillation; ceramic capacitors meeting this spec (e.g., 10 µF X7R, 0805) are preferred. Using higher-ESR electrolytics or undersized CO risks instability, overshoot, and failure to maintain regulation during load steps.