onsemi FAN2504S28X

Overview

FAN2504S28X from Fairchild Semiconductor is a 2.8 V fixed-output CMOS low-dropout (LDO) voltage regulator in SOT-23-5 package, delivering up to 200 mA with 200 mV dropout at full load, 75 µA ground current, and enable/shutdown control - designed for power management in space-constrained portable electronics.

For engineers reviewing the FAN2504S28X datasheet, pinout, applications, or equivalent options, key selection criteria include fixed 2.8 V output, ultra-low quiescent current, thermal protection, bypass-capacitor–enabled noise reduction, and compatibility with ceramic/tantalum output capacitors across wide ESR ranges.

Technical Context

The FAN2504S28X uses a P-channel MOSFET series pass element with ~1 Ω on-resistance, enabling low dropout performance unattainable with bipolar LDOs. Its CMOS error amplifier features low input bias current and references a 1.3 V bandgap, ensuring stable regulation without external feedback resistors for fixed-voltage operation.

Pin 4 functions as BYP (bypass), accepting a 470 pF capacitor to suppress output noise; loop stability is maintained over 10 mΩ–10 Ω ESR output capacitors, eliminating strict capacitor type dependencies seen in legacy LDOs.

Key Specifications

Pinout & Package

SOT-23-5 surface-mount package (EIAJ SC-74A), 2.9 mm × 1.6 mm footprint, 1.1 mm height, with exposed pad not electrically connected - optimized for compact portable PCB layouts and moderate thermal dissipation via PCB copper area.

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 FAN2504S28X uniquely combines fixed 2.8 V output, integrated BYP pin for <7 µV/√Hz noise, and 200 mV dropout - making it optimal for noise-critical 2.8 V analog/digital mixed-signal rails where capacitor-area-constrained designs demand both low ESR tolerance and bypass-enabled spectral purity.

Availability

FAN2504S28X is available at Aetrix Electronics and suitable for cellular phone baseband, portable camera image sensors, laptop subsystem rails, PDA wireless interfaces, and handheld medical monitors requiring stable component supply with guaranteed long-term sourcing.

Supply support for FAN2504S28X 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

Fairchild Semiconductor was a U.S.-based analog and power IC manufacturer acquired by ON Semiconductor in 2016; its legacy LDO portfolio remains widely deployed in portable electronics.

The FAN2504/FAN2505 family was engineered specifically for GSM/TDMA handsets and portable computing, emphasizing micropower operation, low dropout, and SOT-23-5 miniaturization without sacrificing thermal robustness or noise performance.

FAQ

What is the exact output voltage tolerance of the FAN2504S28X?

The FAN2504S28X provides a nominal 2.8 V output with ±2% initial accuracy across temperature and load, as specified in the Electrical Characteristics table under ∆V_OUT. This tolerance holds over the full operating junction temperature range of –40 °C to +125 °C and output currents from 0.1 mA to 200 mA, ensuring reliable voltage margin for 2.8 V logic and analog circuits.

Does the FAN2504S28X require an external bypass capacitor to function?

No, the FAN2504S28X operates stably without a bypass capacitor on pin 4 (BYP). However, connecting a 470 pF capacitor between BYP and GND reduces broadband output noise to <7 µV/√Hz - a design choice for noise-sensitive applications like image sensors or RF receivers. Omitting it incurs no functional penalty for digital-only loads.

Can the FAN2504S28X be used with ceramic output capacitors?

Yes, the FAN2504S28X is explicitly designed for stability with ceramic output capacitors, including X7R and Y5V dielectrics. Its low sensitivity to ESR (10 mΩ–10 Ω) eliminates the need for minimum ESR requirements common in older LDOs, allowing use of small-case, low-ESR 1 µF X7R ceramics without risk of oscillation.

What is the maximum continuous output current for the FAN2504S28X?

The FAN2504S28X is rated for 200 mA continuous output current under conditions where junction temperature remains ≤125 °C. It supports 300 mA peak current for short durations, but sustained >200 mA loads require careful thermal design - including ≥1 in² PCB copper pour - to avoid triggering the 150 °C thermal shutdown.

How does the enable pin (EN) of the FAN2504S28X behave during power-up?

The FAN2504S28X EN pin is active-high with V_IL ≤ 0.4 V (disable) and V_IH ≥ 2.0 V (enable). During power-up, if EN is tied to VIN, the device enables immediately after VIN exceeds ~2.7 V. Floating EN causes erratic behavior; a pullup to VIN or microcontroller GPIO is required for deterministic startup sequencing.