onsemi NCP4561SN28T1

Overview

NCP4561SN28T1 from onsemi is a 2.8 V, 80 mA ultra-low-noise LDO regulator in TSOP-5 package, featuring 40 µV_RMS noise (100 Hz–100 kHz), 90 mV dropout at 30 mA, and 1.0 V ON/OFF control logic - deployed in RF VCO biasing, TDMA burst-mode power rails, and portable audio subsystems.

For engineers reviewing the NCP4561SN28T1 datasheet, pinout, applications, or equivalent options, key selection criteria include output voltage precision (±1.5% @ 25°C), thermal shutdown at 125°C, ripple rejection of −70 dB @ 1 kHz, fast 40 µs wake-up response, and NC pin handling for pin-compatible upgrades.

Technical Context

The NCP4561SN28T1 implements a PNP pass transistor architecture with internal bandgap reference and antisaturation protection, enabling stable regulation without external bypass capacitors. Its load transient improvement circuit actively detects overshoot decay to minimize undershoot during rapid current bursts.

Line regulation remains better than −75 dB static, and its 150 nV/√Hz noise density at 100 Hz supports sensitive analog front-ends. The ON/OFF pin accepts 900 mV logic-high threshold and draws only 0.1 µA in shutdown mode.

Key Specifications

Pinout & Package

TSOP-5 (Case 483) surface-mount package: 2.9 mm × 1.3 mm footprint, 0.95 mm height, lead pitch 0.65 mm - footprint-compatible with SOT-23-5 but with improved thermal resistance (R_JA = 210 °C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1700T-2802E/TT and XC6206P282MR-G, the NCP4561SN28T1 uniquely combines 1.0 V logic-compatible enable, 40 µV_RMS noise, and burst-mode transient hardening - making it the sole option among the three for RF VCO and TDMA burst applications demanding simultaneous low noise, fast wake-up, and low-threshold control.

Availability

NCP4561SN28T1 is available at Aetrix Electronics and suitable for RF VCO power supplies, TDMA burst transceiver bias rails, and portable audio codec biasing requiring stable component supply, full traceability, and lifecycle continuity.

Supply support for NCP4561SN28T1 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 focused on energy-efficient electronics, with leadership in power management, analog, sensing, and connectivity solutions.

The NCP4561SN28T1 belongs to onsemi's ultra-low-noise LDO family designed specifically for noise-sensitive RF, wireless, and portable applications where traditional bypass-capacitor-dependent regulators fail to meet phase-noise or burst-timing requirements.

FAQ

What is the maximum input voltage rating for the NCP4561SN28T1?

The NCP4561SN28T1 supports a maximum input voltage of 12 V on the Vin pin (Pin 5), as specified in the Absolute Maximum Ratings table. Operation above this voltage risks permanent damage. For reliable long-term use at 80 mA output, the input must exceed 2.89 V (2.8 V + 90 mV dropout) and remain within thermal limits - e.g., ≤8.3 V at 25°C ambient per application note calculations.

Does the NCP4561SN28T1 require an external bypass capacitor for noise reduction?

No, the NCP4561SN28T1 does not require an external bypass capacitor. Its proprietary architecture achieves 40 µV_RMS noise (100 Hz–100 kHz) without one - a key differentiator versus conventional LDOs. Adding a bypass capacitor would degrade the 40 µs startup time and is neither recommended nor necessary per the datasheet.

Can Pin 3 (NC) on the NCP4561SN28T1 be connected to ground or left floating?

Pin 3 (NC) on the NCP4561SN28T1 is internally unconnected and must remain floating per the datasheet. The "NC" designation means no internal connection - tying it to ground or any other potential may cause unpredictable behavior or violate layout guidelines. It is retained for mechanical compatibility with pin-to-pin upgrade paths.

What is the guaranteed output voltage tolerance of the NCP4561SN28T1 over temperature?

The NCP4561SN28T1 guarantees output voltage tolerance of ±2.8% over the full operating temperature range (−40°C to +85°C), with typical performance of ±1.5% at 25°C. At −40°C, Vout ranges from 2.716 V to 2.884 V (±3.0% of nominal); at +85°C, the same min/max bounds apply per the Electrical Characteristics table.

How does the NCP4561SN28T1 handle load transients in burst-mode applications?

The NCP4561SN28T1 uses a patented load transient improvement architecture that detects output overshoot decay and forces rapid return to steady-state - minimizing undershoot during subsequent current bursts. This is validated in Figures 13–16, showing <80 mV undershoot when stepping from 0 to 80 mA, critical for TDMA and pulsed RF systems.