onsemi FAN25800AUCF27X-ON

Overview

FAN25800AUCF27X-ON from ON Semiconductor (formerly Fairchild) is a 2.7 V, 500 mA low-noise, low-quiescent-current LDO regulator in a 4-ball WLCSP package. It delivers high PSRR (85 dB at 100 Hz), ultra-low output noise (8 µV_RMS, 10 Hz–100 kHz), and <70 mV dropout at 250 mA - ideal for powering RF sections in WiFi modules and noise-sensitive analog circuitry.

For engineers reviewing the FAN25800AUCF27X-ON datasheet, pinout, applications, or equivalent options, key selection criteria include its 17 µA quiescent current in regulation, stability with dual 1.5 µF 0201 ceramic capacitors, UVLO (2.3 V threshold), and thermal shutdown at 150°C - all critical for battery-powered portable devices requiring long runtime and clean power rails.

Technical Context

The FAN25800AUCF27X-ON implements a PMOS pass transistor architecture enabling low dropout and fast transient response. Its internal bandgap reference and error amplifier deliver ±1.9% output voltage accuracy across load (5–500 mA) and input (2.3–5.5 V) variations.

Control logic integrates enable-driven soft-start (250–500 µs), under-voltage lockout with 150 mV hysteresis, and short-circuit protection limiting output current to 550–800 mA depending on V_OUT. Thermal shutdown disables output until junction temperature falls below 130°C (150°C trip + 20°C hysteresis).

Key Specifications

Pinout & Package

Package: 4-ball Wafer-Level Chip-Scale Package (WLCSP), 0.65 mm × 0.65 mm, 0.35 mm pitch, max height 330 µm. Plated solder bumps enable direct reflow mounting on fine-pitch PCBs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with the FAN25800AUCF27X-ON, the XC6210B272MR-G offers identical V_OUT but reduced current capability and higher dropout, while the RT9080-27GB matches output current and package size but omits UVLO - making the FAN25800AUCF27X-ON uniquely suited for autonomous, battery-critical portable designs requiring integrated protection and minimal quiescent draw.

Availability

FAN25800AUCF27X-ON is available at Aetrix Electronics and suitable for WiFi modules, smartphone RF subsystems, and portable medical sensor hubs requiring stable component supply, consistent parametric performance, and long-term lifecycle support.

Supply support for FAN25800AUCF27X-ON 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

ON Semiconductor is a global semiconductor supplier delivering energy-efficient silicon solutions for automotive, industrial, cloud computing, medical, and IoT applications.

The FAN25800 series was designed specifically for space-constrained, battery-powered portable electronics needing ultra-low-noise, low-I_Q regulation with integrated protection - targeting WiFi, Bluetooth, and cellular RF subsystems.

FAQ

What is the maximum output current supported by the FAN25800AUCF27X-ON at 2.7 V output?

The FAN25800AUCF27X-ON supports up to 500 mA output current when configured for 2.7 V output, as specified in the Ordering Information table and confirmed in the Recommended Operating Conditions section. This rating assumes VIN ≥ VOUT + 0.3 V and ambient temperature between –40°C and +85°C. At higher loads or elevated temperatures, thermal derating per θ_JA = 180°C/W must be applied to avoid exceeding TJ(max) = 125°C.

Does the FAN25800AUCF27X-ON require external compensation components?

No, the FAN25800AUCF27X-ON is internally compensated and stable with two 1.5 µF, 0201-case-size ceramic capacitors on VOUT - as validated in the datasheet's stability testing and Typical Application schematic. No external resistors, capacitors, or feedback networks are needed, simplifying layout and reducing BOM count.

What is the enable pin logic level requirement for the FAN25800AUCF27X-ON?

The EN pin of the FAN25800AUCF27X-ON is active-high with VIH ≥ 1.05 V and VIL ≤ 0.4 V. The datasheet explicitly recommends using a 1.8 V logic driver and warns against tying EN directly to VIN. Since no internal pull-down exists, the pin must be actively driven - floating or weakly biased states may cause unpredictable startup behavior or increased leakage.

Can the FAN25800AUCF27X-ON be used as a post-regulator after a DC-DC converter?

Yes, the FAN25800AUCF27X-ON is explicitly recommended for post-DC-DC regulation in the datasheet's "Typical Application for Post Regulation" section. Its 85 dB PSRR at 100 Hz and low 8 µV_RMS noise make it effective at attenuating switching ripple and high-frequency noise from buck converters, especially in RF and precision analog signal chains powered by the FAN25800AUCF27X-ON.

What package type and dimensions does the FAN25800AUCF27X-ON use?

The FAN25800AUCF27X-ON uses a 4-ball Wafer-Level Chip-Scale Package (WLCSP) measuring 0.65 mm × 0.65 mm with 0.35 mm ball pitch and maximum thickness of 330 µm. Physical dimensions, land pattern recommendations, and solder mask openings are fully documented in the datasheet's "Physical Dimensions" section (Figure 19) and referenced drawing UC004AK.