onsemi LP2951CN

Overview

LP2951CN from onsemi is a micropower, low-dropout linear voltage regulator in an 8-pin PDIP package, delivering up to 100 mA output with ±0.5% initial accuracy at 5.0 V, 75 µA quiescent current, and 350 mV dropout at full load - designed for battery-powered instrumentation requiring precise reset signaling and programmable output.

For engineers reviewing the LP2951CN datasheet, pinout, applications, or equivalent options, key selection criteria include its integrated error flag output for power-on reset generation, logic-level shutdown control, adjustable 1.25–29 V output capability via external resistors, and stability with only a 1.0 µF output capacitor.

Technical Context

The LP2951CN implements a PNP pass transistor architecture with internal 1.235 V bandgap reference, error amplifier, and open-collector error comparator. Its feedback loop accepts direct access at Pin 7 (FB), enabling precise output programming while maintaining tight line regulation (0.04% typical) and load regulation (0.05% typical).

Shutdown is controlled by a TTL/CMOS-compatible input (Pin 3) that reduces regulator output current to ≤10 µA when asserted high; the error output (Pin 5) sinks up to 400 µA when V_OUT drops >5% below nominal, providing reliable undervoltage detection independent of load current.

Key Specifications

Pinout & Package

LP2951CN is housed in an 8-pin plastic dual-in-line package (PDIP-8, Case 626), with 0.3-inch body width and 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 regulator applications.

Compared with LP2951CDR2G and TLV70733PDQNR, the LP2951CN provides unique value in through-hole prototyping and legacy designs where error flag and shutdown integration reduce component count, while maintaining the same precision and dropout performance as its SOIC counterpart.

Availability

LP2951CN is available at Aetrix Electronics and suitable for portable medical devices, industrial I/O modules, smart home hubs, and battery charger reference designs requiring stable component supply, long-term lifecycle support, and RoHS-compliant through-hole packaging.

Supply support for LP2951CN 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 manufacturer specializing in energy-efficient silicon solutions for automotive, industrial, cloud, medical, and IoT applications.

The LP2951CN belongs to onsemi's precision linear regulator product line, engineered for battery-powered and low-noise systems where micropower operation, accurate voltage setting, and integrated supervisory functions are essential.

FAQ

What is the maximum input voltage rating for the LP2951CN?

The LP2951CN has an absolute maximum input voltage rating of 30 V DC under continuous operation, with a peak transient rating of 32 V for durations under 300 ms. Exceeding these limits risks permanent damage. For reliable 5.0 V operation, input should remain between 6.0 V and 30 V per datasheet test conditions - the LP2951CN maintains regulation across this full range with specified line regulation performance.

Can the LP2951CN be used in adjustable-output configurations?

Yes, the LP2951CN supports adjustable output voltages from 1.25 V to 29 V using two external resistors connected to Pins 6 (VO Tap), 7 (Feedback), and 2 (Sense). The output equation is V_OUT = V_REF(1 + R1/R2) + I_FBR1, where V_REF = 1.235 V and I_FB ≤ 40 nA. For 5.0 V fixed output, tie Pin 6 to Pin 7 and Pin 1 to Pin 2 - the LP2951CN then operates identically to its factory-programmed variants.

How does the error output of the LP2951CN function in a microcontroller system?

The LP2951CN error output (Pin 5) is an open-collector comparator that pulls low when V_OUT falls >5% below nominal (e.g., <4.75 V for 5.0 V mode), providing a clean power-on reset signal. It sinks up to 400 µA and requires an external pull-up resistor (100 kΩ to 1 MΩ) to V_OUT or another system rail. In microcontroller systems, this signal connects directly to the RESET pin - the LP2951CN ensures deterministic initialization before firmware execution begins.

What output capacitor is required for stable operation of the LP2951CN?

The LP2951CN requires a minimum 1.0 µF output capacitor for guaranteed stability across all operating conditions, as verified in the datasheet. Aluminum, tantalum, or multilayer ceramic capacitors are acceptable; solid tantalum or appropriate MLCCs are recommended for operation below −25°C. For adjustable configurations below 5.0 V or 100 mA loads, increase to 3.3 µF - the LP2951CN's feedback loop gain reduction at low V_OUT demands higher capacitance to maintain phase margin.

Is the LP2951CN pin-compatible with other regulators in the LP295x family?

The LP2951CN shares identical pinout and functionality with all LP2951 variants in PDIP-8 (e.g., LP2951CD−3.3R2G), differing only in factory-set output voltage or tolerance. It is not pin-compatible with LP2950 (3-pin TO-92/DPAK) or NCV2951 (automotive-grade SOIC/Micro8) due to different package types and marking conventions - the LP2951CN's 8-pin PDIP layout is unique to through-hole LP2951 versions.