onsemi FAN25800AUC33X-ON

Overview

FAN25800AUC33X-ON from ON Semiconductor (formerly Fairchild) is a 3.3 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 portable baseband circuits.

For engineers reviewing the FAN25800AUC33X-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, EN-controlled shutdown (<1 µA I_SD), and thermal/UVLO/short-circuit protection.

Technical Context

The FAN25800AUC33X-ON integrates a PMOS pass transistor with controlled soft-start, enabling inrush current limiting during enable transitions. Its internal reference and error amplifier deliver ±1.9% V_OUT accuracy across load (5–500 mA) and input (2.3–5.5 V) variations.

Protection circuitry includes under-voltage lockout (2.1–2.3 V threshold with 150 mV hysteresis), thermal shutdown at 150°C (20°C hysteresis), and short-circuit current limiting (550–800 mA depending on V_OUT). The device operates over –40°C to +85°C ambient and supports junction temperatures up to +125°C.

Key Specifications

Pinout & Package

Package: 4-ball Wafer-Level Chip-Scale Package (WLCSP), 0.65 mm × 0.65 mm footprint, 0.35 mm pitch, 330 µm max thickness, plated solder bumps.

Key Features

Applications

Equivalent & Alternatives

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

Compared with Torex XC6210B332MR-G and Richtek RT9013-33GB, the FAN25800AUC33X-ON offers superior noise performance (8 µV_RMS vs. ≥15 µV_RMS), tighter dropout (<70 mV), and integrated soft-start - making it the preferred choice for RF and battery-constrained applications demanding clean, efficient, and protected regulation.

Availability

FAN25800AUC33X-ON is available at Aetrix Electronics and suitable for WiFi modules, smartphone baseband subsystems, and portable medical sensors requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for FAN25800AUC33X-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, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The FAN25800 series belongs to ON Semiconductor's ultra-low-noise LDO portfolio, engineered specifically for noise-critical RF and portable electronics where PSRR, output noise, and quiescent current are design-defining parameters.

FAQ

What is the maximum output current supported by the FAN25800AUC33X-ON?

The FAN25800AUC33X-ON delivers up to 500 mA of continuous output current when configured for 3.3 V output, as specified in the ordering information and electrical characteristics table. This rating assumes VIN ≥ VOUT + 0.3 V and operation within the recommended ambient temperature range (–40°C to +85°C). At higher loads or elevated temperatures, thermal derating per θ_JA = 180°C/W must be applied to maintain safe junction temperature.

Does the FAN25800AUC33X-ON require external compensation components?

No, the FAN25800AUC33X-ON is internally compensated and designed to be stable with minimal external components: specifically, two 1.5 µF, 0201-size X5R ceramic capacitors (one on VIN, one on VOUT). The datasheet confirms stability across 0.4–15 µF effective output capacitance with ESR between 3–100 mΩ - eliminating need for external resistors or capacitors in the feedback path.

How does the enable (EN) pin function on the FAN25800AUC33X-ON?

The EN pin on the FAN25800AUC33X-ON is an active-high digital control input. When pulled to ≥1.05 V (VIH), the regulator powers up with controlled soft-start; when pulled to ≤0.4 V (VIL), it enters shutdown mode drawing <1 µA. The pin has no internal pull-down, so it must be actively driven - floating or weakly biased states are prohibited. Recommended drive voltage is 1.8 V logic level.

What protection features are integrated into the FAN25800AUC33X-ON?

The FAN25800AUC33X-ON integrates three core protections: input under-voltage lockout (UVLO) with 2.1–2.3 V threshold and 150 mV hysteresis; thermal shutdown at 150°C with 20°C hysteresis; and short-circuit current limiting (550–800 mA depending on VOUT). These functions operate autonomously without external circuitry, ensuring safe operation during fault conditions and abnormal thermal environments.

Can the FAN25800AUC33X-ON be used as a post-regulator after a DC-DC converter?

Yes, the FAN25800AUC33X-ON is explicitly designed for post-DC-DC regulation. Its 85 dB PSRR at 100 Hz and ultra-low 8 µV_RMS output noise effectively filter switching ripple and high-frequency noise from buck converters. The datasheet provides a validated reference design (Figure 17) showing shared input capacitance between the DC-DC stage and the FAN25800AUC33X-ON, simplifying layout and reducing component count.