onsemi NCP551SN50T1

Overview

NCP551SN50T1 from onsemi is a fixed-output, low-dropout linear voltage regulator delivering 150 mA with ultra-low 4.0 µA quiescent current, ±2.0% output voltage accuracy, and 5.0 V nominal output. It employs a PMOS pass transistor, integrates thermal shutdown and current limit protection, and is optimized for battery-powered portable equipment requiring stable low-power regulation.

For engineers reviewing the NCP551SN50T1 datasheet, pinout, applications, or equivalent options, key selection considerations include dropout voltage at 150 mA load, enable threshold compatibility with system logic, TSOP-5 thermal performance under 12 V max input, and ceramic capacitor stability with ≥0.1 µF output capacitance.

Technical Context

The NCP551SN50T1 uses a PMOS pass element enabling true low-dropout operation-dropout is only 150 mV at 10 mA and remains ≤250 mV across full 150 mA load range for 5.0 V output. Its internal error amplifier and voltage reference achieve ±2.0% initial accuracy and ±100 ppm/°C temperature coefficient, ensuring tight regulation over −40 °C to +85 °C ambient.

Enable functionality is implemented via a dedicated logic-level input (V_TH(on) = 1.3 V, V_TH(off) = 0.3 V) that places the device in standby with <0.1 µA quiescent current when pulled low. The regulator requires no minimum load and remains stable with ceramic capacitors as low as 0.1 µF, eliminating ESR constraints typical of older LDO architectures.

Key Specifications

Pinout & Package

The NCP551SN50T1 is housed in a 5-pin TSOP-5 (SOT-23-5, Case 483) surface-mount package measuring 3.00 × 1.50 × 0.95 mm with 0.95 mm pitch. Thermal resistance is R_JA = 250 °C/W (1 oz Cu, 100 mm² pad), requiring minimal copper area for typical 150 mA operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-quiescent-current LDO regulator applications.

Compared with MCP1700T-5002E/TT and TPS70650DBVR, the NCP551SN50T1 offers identical quiescent current and superior dropout at light loads, retains the N/C pin for layout flexibility, and provides a robust enable threshold (1.3 V turn-on) compatible with 1.8 V/3.3 V logic without level-shifting.

Availability

NCP551SN50T1 is available at Aetrix Electronics and suitable for portable medical sensors, battery-powered data loggers, handheld test instruments, and industrial remote I/O modules requiring stable component supply with long-term lifecycle support.

Supply support for NCP551SN50T1 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 (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power management, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The NCP551 series belongs to onsemi's precision low-dropout linear regulator product line, designed specifically for ultra-low-power portable electronics where battery longevity, small footprint, and ceramic capacitor compatibility are critical.

FAQ

What is the maximum input voltage rating for the NCP551SN50T1?

The NCP551SN50T1 has an absolute maximum input voltage of 12 V. Operation above this level risks permanent damage. For applications with higher source voltages (e.g., 24 V industrial rails), a pre-regulator stage is required before the NCP551SN50T1 input. The device is rated for continuous operation up to 12 V, with recommended design margin maintained at ≤11.5 V for reliability.

Does the NCP551SN50T1 require an external output capacitor, and what value is recommended?

Yes, the NCP551SN50T1 requires an external output capacitor for stability. A minimum of 0.1 µF ceramic capacitor is mandatory and must be placed adjacent to the Vout (Pin 5) and GND (Pin 2) terminals. Larger values (e.g., 1.0–10 µF) improve load transient response and noise rejection. Unlike older LDOs, it imposes no ESR requirement and remains stable with low-ESR ceramics.

How does the enable pin function on the NCP551SN50T1, and what are its voltage thresholds?

The Enable pin (Pin 3) is active-high. The NCP551SN50T1 turns on when the enable voltage rises above 1.3 V (typical) and turns off when it falls below 0.3 V (typical). When disabled, quiescent current drops to <0.1 µA. If unused, Enable must be tied directly to Vin-floating or weakly pulled inputs may cause erratic behavior. No external pull-up resistor is needed when connected to Vin.

What is the dropout voltage of the NCP551SN50T1 at full 150 mA load?

At 150 mA output current and 25 °C, the dropout voltage of the NCP551SN50T1 is ≤250 mV. This means the device maintains 5.0 V regulation as long as Vin ≥ 5.25 V. Dropout increases slightly at higher temperatures and lower input voltages but remains within specification across the full −40 °C to +85 °C operating range per the datasheet's electrical characteristics table.

Is the NCP551SN50T1 RoHS compliant and lead-free?

Yes, the NCP551SN50T1 is RoHS compliant and lead-free. It carries the "G" suffix in its full orderable part number (NCP551SN50T1G) and is packaged in a Pb-free TSOP-5 case (Case 483). The device meets EU RoHS Directive 2011/65/EU and is marked with the Pb-free indicator per onsemi's packaging specifications.