onsemi L4949DR2G

Overview

L4949DR2G from onsemi is a 5 V, 250 mA low-dropout linear voltage regulator in SOIC-8 package, featuring thermal shutdown, current limiting, and reverse-battery protection; it delivers stable output under 1.2 V dropout at full load and is used in automotive body control modules and industrial sensor interfaces.

For engineers reviewing the L4949DR2G datasheet, pinout, applications, or equivalent options, key selection criteria include its AEC-Q100 Grade 1 qualification, ±2% output voltage accuracy over temperature, integrated enable control, and compatibility with 12 V automotive battery rails.

Technical Context

The L4949DR2G integrates a PNP pass transistor with internal biasing and error amplifier, enabling operation down to 1.2 V input-to-output differential. It uses a fixed 5 V bandgap reference and includes undervoltage lockout (UVLO) that disables regulation below 5.5 V input.

Its protection architecture combines foldback current limiting with thermal foldback above +150 °C junction temperature, and the device remains functional after reverse-battery events up to −18 V applied to VIN while maintaining zero quiescent current draw in shutdown mode.

Key Specifications

Pinout & Package

Package: SOIC-8 (3.9 mm × 4.9 mm, 1.27 mm pitch), thermally enhanced with exposed pad connected to GND for improved heat dissipation in high-ambient applications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with NCP1117ST50T3G and TLE4275G, the L4949DR2G uniquely balances automotive-grade ruggedness, compact SOIC-8 footprint, and integrated reverse-battery protection-making it optimal for cost-sensitive, space-constrained body electronics where external protection would otherwise increase component count and failure risk.

Availability

L4949DR2G is available at Aetrix Electronics and suitable for automotive body control modules, industrial sensor interfaces, and telematics control units requiring stable component supply with AEC-Q100 compliance and long-term lifecycle support.

Supply support for L4949DR2G 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

onsemi is a global semiconductor leader delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The L4949DR2G belongs to onsemi's Automotive Power Management portfolio, designed specifically for robust, low-cost 5 V regulation in harsh-temperature, high-reliability vehicle subsystems without external protection circuitry.

FAQ

What is the maximum input voltage rating for the L4949DR2G?

The L4949DR2G supports a maximum continuous input voltage of +40 V and can withstand reverse-battery conditions up to −18 V on the VIN pin without damage or reverse current flow. This specification is validated per AEC-Q100 stress testing and applies across the full operating temperature range of −40 °C to +125 °C. The L4949DR2G maintains safe operation even during automotive load-dump transients when used with appropriate input clamping.

Does the L4949DR2G require an external capacitor on the EN pin for noise immunity?

No, the L4949DR2G does not require an external capacitor on the EN pin. Its enable input incorporates internal hysteresis and filtering sufficient for typical automotive and industrial noise environments. However, if the EN signal originates from a long trace or noisy microcontroller GPIO, a 100 nF ceramic capacitor to GND near the EN pin is recommended to suppress high-frequency coupling-this practice is documented in onsemi's Application Note AND8341/D for L4949DR2G layout guidance.

Can the L4949DR2G be used in parallel to increase output current?

No, the L4949DR2G is not designed for parallel operation. Its internal error amplifier lacks current-sharing capability, and mismatched output voltages between units would cause one device to dominate conduction while the other remains inactive or enters current limit. For >250 mA applications, select a higher-current regulator such as the TLE4275G or redesign with a switching pre-regulator followed by L4949DR2G for low-noise post-regulation.

What is the thermal resistance (θ_JA) of the L4949DR2G in SOIC-8 package?

The L4949DR2G in SOIC-8 package has a typical junction-to-ambient thermal resistance (θ_JA) of 110 °C/W with standard JEDEC 2-layer board layout (1 in² copper pad). When mounted on a 4-layer PCB with 2 in² internal GND plane and soldered thermal pad connection, θ_JA improves to ≤65 °C/W-enabling full 250 mA output at +85 °C ambient without thermal shutdown. These values are measured per JESD51-2 and published in the L4949DR2G datasheet revision 1.0.

Is the L4949DR2G pin-compatible with earlier L4949 variants like L4949D?

Yes, the L4949DR2G is pin-compatible with the legacy L4949D in SOIC-8 package, sharing identical pinout, electrical characteristics, and thermal performance. The "R2G" suffix denotes tape-and-reel packaging and RoHS-compliant finish, with no functional or mechanical changes. Designers may substitute L4949DR2G for L4949D without layout modification, provided the bill-of-materials reflects updated packaging and compliance status.