onsemi FAN2505S30X

Overview

FAN2505S30X from Fairchild Semiconductor is a 3.0 V fixed-output CMOS low-dropout (LDO) voltage regulator in SOT-23-5 package, delivering up to 200 mA output current with 200 mV dropout at full load, 75 µA ground current at 200 mA, and enable/shutdown control - designed for power management in portable battery-powered systems such as cellular handsets and notebook computers.

For engineers reviewing the FAN2505S30X datasheet, pinout, applications, or equivalent options, key selection criteria include its open-drain ERR flag for output fault monitoring, thermal shutdown at 150°C, ±2% output voltage accuracy, PSRR of 43 dB at 120 Hz, and compatibility with low-ESR ceramic, tantalum, or aluminum electrolytic output capacitors from 1 µF to >10 µF.

Technical Context

The FAN2505S30X uses a P-channel MOSFET series pass element with ~1 Ω on-resistance, enabling ultra-low dropout performance compared to bipolar LDOs. Its error amplifier features low-drift bandgap reference (1.3 V nominal) and high loop stability across wide ESR ranges (10 mΩ to 10 Ω), eliminating strict capacitor selection constraints.

Pin 4 functions as an open-drain ERR flag indicating output voltage drop below 95% of nominal (3.0 V), with 3 ms response time and recommended 100 kΩ pull-up. Thermal protection disables output above 150°C junction temperature and re-enables automatically upon cooling.

Key Specifications

Pinout & Package

SOT-23-5 surface-mount package (JEDEC SC-74A, 2.9 × 1.6 × 1.1 mm), thermally enhanced with component-side copper recommended for θ_JA down to ~130°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with FAN2505S30X, MCP1700T-3002E/TT offers lower quiescent current but omits fault reporting, while TLC7733IPK adds reset timing but lacks thermal protection and operates at 3.3 V - making FAN2505S30X uniquely suited for 3.0 V battery-powered systems requiring both precision regulation and real-time output health monitoring.

Availability

FAN2505S30X is available at Aetrix Electronics and suitable for cellular handsets, portable cameras, and notebook subsystems requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for FAN2505S30X 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 semiconductor company specializing in power management, analog, and discrete ICs, acquired by ON Semiconductor in 2016; its legacy LDO portfolio remains widely deployed in portable electronics.

The FAN2504/FAN2505 family was engineered for compact battery-powered devices, emphasizing ultra-low power consumption, low dropout, and robust capacitor compatibility - targeting GSM/TDMA handsets, laptops, and portable imaging equipment.

FAQ

What is the function of pin 4 on the FAN2505S30X?

Pin 4 on the FAN2505S30X is the ERR (Error) terminal - an open-drain output that goes LOW when the regulated output voltage drops below 95% of nominal (i.e., below 2.85 V). It signals fault conditions including input undervoltage, thermal shutdown, or overload. A 100 kΩ pull-up resistor to VIN is recommended for proper logic-level interpretation. This differs from the FAN2504S30X, where pin 4 is BYP for noise reduction.

What is the maximum continuous output current for the FAN2505S30X?

The FAN2505S30X is rated for 200 mA continuous output current under specified thermal conditions (T_J ≤ 125°C). While it can deliver up to 300 mA peak current briefly, sustained operation above 200 mA risks triggering thermal shutdown at 150°C unless PCB copper area and airflow are optimized to reduce θ_JA. The 200 mA rating assumes typical layout with ≥1 in² of component-side copper pour.

Does the FAN2505S30X require an external bypass capacitor?

No - the FAN2505S30X does not use a bypass capacitor. Unlike the FAN2504-XX variants (which use pin 4 as BYP), the FAN2505S30X assigns pin 4 as ERR. Therefore, no bypass capacitor is connected to pin 4. However, a 1 µF or larger ceramic output capacitor between VOUT and GND is mandatory for loop stability, and a 2.2 µF input capacitor is recommended for transient response.

How does the enable function operate on the FAN2505S30X?

The EN pin (pin 3) of the FAN2505S30X is active-high: applying ≥2.0 V enables regulation, while ≤0.4 V disables the output and reduces ground current to <1 µA. Floating the EN pin causes erratic behavior, so it must be tied to VIN (for always-on) or driven by a GPIO. The enable response time is 500 µs, supporting fast power sequencing in multi-rail systems.

What thermal resistance values apply to the FAN2505S30X in SOT-23-5 package?

The FAN2505S30X in SOT-23-5 has θ_JC = 130°C/W (junction-to-case) and θ_JA ≈ 220–235°C/W for minimum footprint, improving to ~130°C/W with 4 in² of component-side copper. These values determine maximum power dissipation: at T_A = 85°C, max P_D ≈ 150 mW for bare footprint, rising to ~540 mW with full copper enhancement - directly impacting safe 200 mA operation across ambient temperatures.