onsemi FAN2502S27X

Overview

FAN2502S27X from Fairchild Semiconductor is a 2.7 V fixed-output, CMOS-based low-dropout (LDO) voltage regulator in SOT-23-5 package, delivering up to 150 mA output current with 150 mV dropout at full load, 25 µA ground current at 150 mA, and enable/shutdown control. It serves as a power management IC for portable battery-powered systems requiring stable, low-noise, low-quiescent-power regulation.

For engineers reviewing the FAN2502S27X datasheet, pinout, applications, or equivalent options, key selection criteria include fixed 2.7 V output, bypass-capacitor–enabled noise performance, thermal shutdown protection, SOT-23-5 footprint compatibility, and sub-1 µA shutdown current.

Technical Context

The FAN2502S27X uses a P-channel MOSFET series pass element with ~1 Ω on-resistance, enabling ultra-low dropout operation. Its error amplifier compares V_OUT against an internal 1.32 V bandgap reference and supports stable regulation across wide ESR ranges (10 mΩ to 10 Ω) of external output capacitors.

Pin 4 functions as BYP - a passive node for connecting a 470 pF bypass capacitor to reduce output noise - distinguishing it from adjustable (ADJ) or error-flag (ERR) variants. Thermal protection activates at 150 °C junction temperature, disabling output until die cools.

Key Specifications

Pinout & Package

SOT-23-5 surface-mount package with 1.3 mm × 2.9 mm footprint, 1.45 mm height, and EIAJ SC-74A standard outline. Designed for high-density portable PCB layouts with minimal thermal pad area requirements.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1700T-2702E/TT and TLC7703IPW, the FAN2502S27X uniquely combines 2.7 V regulation, SOT-23-5 footprint, and a dedicated BYP pin for deterministic noise reduction - making it optimal for space-constrained, noise-critical portable applications where capacitor flexibility and thermal robustness are essential.

Availability

FAN2502S27X is available at Aetrix Electronics and suitable for cellular phone baseband, portable camera sensor rail, and laptop subsystem logic requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for FAN2502S27X 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 FAN2502/03 family was designed specifically for GSM/TDMA handsets and portable computing, emphasizing micropower operation, low dropout, and SOT-23-5 integration - targeting battery runtime and board space constraints.

FAQ

What is the maximum input voltage for the FAN2502S27X?

The FAN2502S27X supports an absolute maximum input voltage of 7 V, with recommended operating range from 2.7 V to 6.5 V. Exceeding 7 V risks permanent damage per Absolute Maximum Ratings. For reliable 2.7 V output regulation, minimum input must exceed 2.85 V to accommodate the 150 mV dropout at full 150 mA load. The FAN2502S27X maintains regulation across this full input span while holding output accuracy within ±2%.

Does the FAN2502S27X require an external bypass capacitor?

The FAN2502S27X does not require an external bypass capacitor to operate, but connecting a 470 pF capacitor between Pin 4 (BYP) and GND significantly reduces output noise - especially critical in RF, audio, or high-resolution imaging applications. Without it, broadband noise remains below 7 µV/√Hz (10 Hz–1 kHz); with it, noise is further suppressed. The FAN2502S27X BYP pin is high-impedance, so capacitor leakage must be minimized using X7R or NP0 ceramics.

How does thermal protection work in the FAN2502S27X?

The FAN2502S27X incorporates die-level thermal protection that disables V_OUT when junction temperature reaches 150 °C, then automatically re-enables once temperature falls below the hysteresis threshold. This prevents catastrophic failure during sustained overload or inadequate PCB copper area. During thermal shutdown, the FAN2502S27X draws only I_GND × V_IN power - and users may simultaneously assert EN = 0 V to reduce consumption to <1 µA. The SOT-23-5 package's θ_JA ranges from 130 °C/W (with 4 in² copper) to 235 °C/W (minimum footprint).

Can the FAN2502S27X be used with ceramic output capacitors?

Yes, the FAN2502S27X is explicitly designed for stable operation with ceramic output capacitors ranging from 1 µF to 10 µF and ESR values between 10 mΩ and 10 Ω - unlike many older LDOs requiring precise ESR tuning. X7R or Y5V dielectrics are recommended for optimal temperature coefficient behavior. The FAN2502S27X achieves this via innovative error amplifier compensation, eliminating the need for series resistance or external RC networks typically required with low-ESR ceramics.

What is the enable logic threshold for the FAN2502S27X?

The FAN2502S27X EN pin asserts logic-high enable when voltage exceeds 2.0 V (typical VIH), and logic-low shutdown when voltage drops to ≤0.4 V (typical VIL). If unused, EN must be tied directly to V_IN; floating the pin causes erratic output behavior. In shutdown mode, the FAN2502S27X draws less than 1 µA total supply current - critical for battery-backed systems. Response time from enable assertion to regulated V_OUT is 500 µs maximum.