onsemi LP2951ACN-3.3G

Overview

LP2951ACN-3.3G from onsemi is a micropower, low-dropout linear voltage regulator in an 8-pin PDIP (Plastic Dual-In-Line) package, delivering a precise 3.3 V ±0.5% output at up to 100 mA. It features an error output for power-on reset or out-of-regulation signaling, logic-level shutdown control, and programmable feedback for adjustable output configurations. It is widely used in battery-powered instrumentation and microcontroller power rails where quiescent current and dropout performance are critical.

For engineers reviewing the LP2951ACN-3.3G datasheet, pinout, applications, or equivalent options, key selection criteria include its 75 µA quiescent current, 350 mV dropout at 100 mA, ±0.5% initial output tolerance, error flag timing behavior, and SOIC-8/PDIP-8 package compatibility with legacy through-hole designs.

Technical Context

The LP2951ACN-3.3G integrates a precision 1.235 V bandgap reference, error amplifier with external feedback access (Pin 7), open-collector error comparator (Pin 5), and CMOS/TTL-compatible shutdown input (Pin 3). Its architecture supports both fixed-output (3.3 V via internal resistor divider) and adjustable modes (1.25–29 V) using external resistors between Pin 7 (FB), Pin 6 (VO Tap), and ground.

Thermal regulation is internally managed with junction temperature limiting, and stability requires ≥1.0 µF output capacitance (aluminum, tantalum, or multilayer ceramic). The device operates across −40°C to +125°C ambient and tolerates input voltages up to 30 V DC with peak transient rating of 32 V for <300 ms.

Key Specifications

Pinout & Package

LP2951ACN-3.3G uses an 8-pin PDIP (Plastic Dual-In-Line) package (Case 626), with leads bent for through-hole mounting. Thermal resistance is 105°C/W (junction-to-ambient), suitable for moderate-power applications without heatsinking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LP2951ACD-3.3R2G and NCV2951ACD-3.3R2G, the LP2951ACN-3.3G offers identical regulation performance and feature set in a legacy PDIP package-ideal for prototyping, repair, or industrial equipment where through-hole reliability and hand-soldering are preferred.

Availability

LP2951ACN-3.3G is available at Aetrix Electronics and suitable for portable medical sensors, industrial PLC I/O modules, automotive body control units, and smart home hub power management requiring stable component supply across long-lifecycle programs.

Supply support for LP2951ACN-3.3G 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 supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The LP2951 series is part of onsemi's precision analog portfolio, designed specifically for ultra-low-quiescent, low-dropout regulation in battery-constrained and thermally sensitive systems where accuracy, reliability, and design flexibility are essential.

FAQ

What is the maximum input voltage rating for the LP2951ACN-3.3G?

The LP2951ACN-3.3G has an absolute maximum input voltage of 30 V DC under continuous operation, with a peak transient rating of 32 V for durations under 300 ms. Exceeding these limits may cause permanent damage. For robust operation in automotive environments, the NCV2951ACD-3.3R2G variant is recommended due to its validated load-dump immunity and AEC-Q100 qualification.

How does the error output of the LP2951ACN-3.3G behave during startup and brown-out conditions?

The LP2951ACN-3.3G error output is an open-collector pin that goes low when the regulated output falls more than ~5% below nominal (i.e., below ~3.135 V for the 3.3 V version), regardless of load. During startup, it remains high until the output reaches regulation; during brown-out, it asserts low before the output collapses fully, providing early warning. An external pull-up resistor (100 kΩ to 1 MΩ) to VOUT is required for proper logic-level signaling.

Can the LP2951ACN-3.3G be used in adjustable-output mode, and what is the minimum output voltage achievable?

Yes, the LP2951ACN-3.3G supports adjustable-output mode via Pins 6 (VO Tap), 7 (Feedback), and 2 (Sense). The minimum output voltage is 1.25 V - set by the internal 1.235 V reference plus feedback network headroom. To achieve 1.25 V, connect Pin 1 (Output) to Pin 2 (Sense), tie Pin 7 to ground through R2, and apply feedback from Pin 6 to Pin 7 through R1. Full range is 1.25 V to 29 V, limited only by input voltage and thermal constraints.

What output capacitor value and type are required for stable operation of the LP2951ACN-3.3G?

The LP2951ACN-3.3G requires a minimum 1.0 µF output capacitor connected between Pin 1 (Output) and Pin 8 (GND) for guaranteed stability. Aluminum electrolytic, solid tantalum, or multilayer ceramic capacitors are acceptable. For operation below −25°C, solid tantalum or appropriate MLCCs are recommended. Capacitor ESR should be <1 Ω; values below 0.33 µF are only stable at loads <10 mA.

Does the LP2951ACN-3.3G include thermal shutdown and current limiting protection?

Yes, the LP2951ACN-3.3G includes internal thermal shutdown and current limiting protection. Thermal shutdown activates when die junction temperature exceeds +150°C, disabling the output until safe temperature is restored. Current limiting engages at approximately 220–300 mA (typical) when the output is shorted to ground, preventing damage during fault conditions. These protections operate independently of external components and require no user configuration.