onsemi LP2951ACNG

Overview

LP2951ACNG from onsemi is a micropower, low-dropout linear voltage regulator in an 8-pin SOIC package, delivering up to 100 mA with ±0.5% initial output voltage accuracy at 25°C, 5.0 V nominal output, and dropout as low as 350 mV at full load - used in battery-powered instrumentation requiring stable low-noise supply and power-on reset signaling.

For engineers reviewing the LP2951ACNG datasheet, pinout, applications, or equivalent options, this page delivers verified technical context, validated pin functions, real-world application cards, and two confirmed alternative parts with documented functional and packaging differences for embedded power design.

Technical Context

The LP2951ACNG integrates a precision 1.235 V bandgap reference, error amplifier with external feedback access (Pin 7), open-collector error comparator (Pin 5), and logic-level shutdown input (Pin 3). Its architecture supports both fixed 5.0 V operation and adjustable outputs from 1.25 V to 29 V via resistor divider networks.

It employs internal current limiting and thermal shutdown, requires only a 1.0 µF output capacitor for stability, and maintains regulation down to 50 mV differential at light load (100 µA) - enabling extended battery life in portable systems where quiescent current (75 µA typ.) and low dropout are critical.

Key Specifications

Pinout & Package

LP2951ACNG uses an 8-pin SOIC-8 (Case 751) surface-mount package with exposed pad thermal enhancement. Pin 1 is Output, Pin 2 is Sense, Pin 3 is Shutdown, Pin 4 is Ground, Pin 5 is Error Output, Pin 6 is VO Tap, Pin 7 is Feedback, and Pin 8 is Input.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LP2951CDR2G, the LP2951ACNG offers tighter initial accuracy for precision analog subsystems; compared with NCV2951ACDR2G, it lacks automotive qualification but provides identical performance at lower cost for industrial or consumer use.

Availability

LP2951ACNG is available at Aetrix Electronics and suitable for battery-powered instrumentation, microcontroller power management, industrial sensor nodes, and automotive body control modules requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for LP2951ACNG 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 (Nasdaq: ON) is a global semiconductor leader delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The LP2951ACNG belongs to onsemi's precision low-dropout linear regulator product line, designed specifically for battery-operated and space-constrained systems demanding ultra-low quiescent current, high accuracy, and integrated power-management features.

FAQ

What is the maximum input voltage rating for the LP2951ACNG?

The LP2951ACNG has an absolute maximum input voltage rating of 30 V DC. It also supports peak transient input up to 32 V for durations under 300 ms. Exceeding these limits risks permanent damage. For continuous operation, keep input within 30 V and ensure sufficient thermal margin based on load current and PCB copper area per Figure 29 in the datasheet.

Can the LP2951ACNG be used in adjustable-output configurations?

Yes, the LP2951ACNG supports adjustable output voltages from 1.25 V to 29 V using external resistors R1 and R2 connected to the Feedback (Pin 7) and GND (Pin 4). The output equation is VOUT = VREF × (1 + R1/R2) + IFB × R1, where VREF = 1.235 V and IFB ≈ −20 nA. For best accuracy, use R2 = 100 kΩ to limit IFB-induced error to ~0.17%.

How does the Error Output pin function in the LP2951ACNG?

The Error Output (Pin 5) is an open-collector comparator output that goes low when the regulated output drops more than ~5.0% below nominal (e.g., <4.75 V for 5.0 V output). It sinks up to 400 µA and requires an external pull-up resistor (100 kΩ to 1 MΩ) - preferably to VOUT - to avoid invalid high state during power-down. This signal serves as a precise power-on reset or brownout indicator.

What is the minimum output capacitance required for stability with the LP2951ACNG?

The LP2951ACNG requires a minimum 1.0 µF ceramic or tantalum output capacitor connected between Pin 1 (Output) and Pin 4 (GND) for guaranteed stability across all loads and temperatures. Using smaller values (e.g., 0.33 µF) is only acceptable at loads <10 mA; for adjustable configurations at low output voltages (<5.0 V), ≥3.3 µF is recommended to maintain phase margin.

Does the LP2951ACNG include thermal and current protection?

Yes, the LP2951ACNG integrates both thermal shutdown and current limiting. Internal thermal protection disables the output if junction temperature exceeds ~150°C, and current limiting activates at ~220–300 mA (typ.) during output short-circuit or overload conditions. These protections are fully internal - no external components are needed, and they automatically reset once fault conditions clear.