onsemi NCP5661MN28T2G

Overview

NCP5661MN28T2G from onsemi is a fixed-output, 2.8 V, 1.0 A ultra-low-dropout linear regulator in a thermally robust DFN6 3×3.3 mm package. It delivers ultra-fast transient response (1–3 µs settling), low ground current (≤3.0 mA at 1.0 A), and 26 µV_rms output noise without bypass capacitor-ideal for post-regulation in high-performance ASIC power supplies and networking equipment.

For engineers reviewing the NCP5661MN28T2G datasheet, pinout, applications, or equivalent options, key selection criteria include dropout voltage ≤1.3 V at 1.0 A, enable functionality with 1.3 V logic-high threshold, error flag output for 2.8 V regulation monitoring, and thermal shutdown at 160°C.

Technical Context

The NCP5661MN28T2G integrates a 0.9 V internal reference and precision error amplifier to regulate 2.8 V output with ±1% accuracy at 25°C and ±2% over −40°C to +150°C. Its architecture maintains low ground current independent of load and achieves >65 dB ripple rejection at 1 kHz.

It features an active-low open-drain Error Flag (Pin 5) triggered when output falls below 88% of nominal (i.e., <2.464 V), requiring a 100 kΩ pull-up to VIN. Enable control (Pin 1) supports system-level power sequencing with 0.3 V logic-low disable threshold and ≤0.5 µA input current.

Key Specifications

Pinout & Package

Package: DFN6 (3.0 × 3.3 mm, 0.95 mm pitch), thermally enhanced with exposed pad (EPAD) connected to GND for optimal heat dissipation (R_θJL = 18°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS7A4700RGWR and ADP1741ACPZ-R7, the NCP5661MN28T2G uniquely combines fixed 2.8 V output, integrated error flag, ultra-low 26 µV_rms noise, and DFN6 footprint-making it optimal for space-constrained, fault-aware, high-integrity power domains.

Availability

NCP5661MN28T2G is available at Aetrix Electronics and suitable for ASIC power supplies, networking equipment, and server memory subsystems requiring stable component supply, long-term lifecycle support, and Pb-free compliance.

Supply support for NCP5661MN28T2G 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 NCP5661 series was designed as a high-current, ultra-fast-response LDO family targeting post-regulation in high-density computing and communications infrastructure-emphasizing thermal robustness, low noise, and system-level fault visibility.

FAQ

What is the maximum input voltage rating for the NCP5661MN28T2G?

The NCP5661MN28T2G has an absolute maximum input voltage (VIN) rating of 18 V. However, its recommended operating input range is 2.0 V to 9.0 V per electrical characteristics. Exceeding 9.0 V may degrade long-term reliability or trigger thermal shutdown under high load, even if within absolute max ratings.

Does the NCP5661MN28T2G require an external bypass capacitor for low-noise operation?

No, the NCP5661MN28T2G achieves 26 µV_rms output noise (10 Hz–100 kHz) without any external bypass capacitor. This is enabled by its internal low-noise architecture and 0.9 V reference design-reducing component count and PCB area versus traditional LDOs requiring 1–10 µF ceramic bypass caps.

How does the Error Flag pin function on the NCP5661MN28T2G?

The Error Flag (Pin 6) is an open-drain output that pulls low when VOUT drops below 88% of nominal (2.464 V for NCP5661MN28T2G). It requires a 100 kΩ pull-up resistor to VIN. The flag remains asserted for ≥50 µs after fault onset, providing noise-immune undervoltage detection for host microcontroller monitoring.

What thermal performance can be expected from the NCP5661MN28T2G in a standard PCB layout?

In a 1 oz copper layout with 1 in² thermal pad area, the NCP5661MN28T2G achieves R_θJA = 82°C/W. At 1.0 A load with 3.8 V input (1.0 V dropout), power dissipation is ~1.0 W-resulting in ~82°C junction rise above ambient. For continuous 1.0 A operation, keep ambient ≤68°C or enhance copper area to meet 150°C max TJ.

Is the NCP5661MN28T2G pin-compatible with other variants in the NCP5661 family?

Yes, all DFN6-packaged NCP5661 variants-including NCP5661MN15T2G (1.5 V), NCP5661MN25T2G (2.5 V), and NCP5661MN33T2G (3.3 V)-share identical pinout, package dimensions, and thermal pad layout. Only the output voltage and marking differ; no PCB redesign is needed when swapping fixed-voltage versions.