FAN53611AUC11X: Advanced 6MHz Synchronous Buck Regulator for Space-Constrained Designs

The FAN53611AUC11X from onsemi represents the next generation of high-performance step-down DC-DC switching regulators, combining industry-leading power density with exceptional efficiency. This comprehensive guide explores every aspect of this innovative power management IC to help engineers optimize their designs.

In-Depth Technical Specifications

Power Conversion Characteristics

• Input Voltage Range: 2.3V to 5.5V (ideal for Li-Ion battery and USB-powered applications)
• Fixed Output Voltage: 1.1V 1.5% accuracy
• Maximum Output Current: 1A continuous (with 1.5A peak capability)
• Switching Frequency: 6MHz (enables tiny external components)

Efficiency Performance

The FAN53611AUC11X achieves outstanding efficiency across its operating range:

• 92% efficiency at 3.6V input, 1.1V/600mA output
• 90% efficiency at 2.7V input, 1.1V/300mA output
• Integrated synchronous rectification eliminates Schottky diode losses

Package and Board Layout Considerations

Ultra-Compact Packaging

• Package Type: 6-ball Wafer Level Chip Scale Package (WLCSP)
• Dimensions: 1.23mm 0.88mm 0.6mm (industry-leading footprint)
• Ball Pitch: 0.4mm (requires careful PCB layout)

Thermal Management

Despite its tiny size, the FAN53611AUC11X features excellent thermal characteristics:

• Junction-to-ambient thermal resistance: 110 C/W
• Automatic thermal shutdown at 150 C
• Recommended PCB thermal vias under exposed pad

Design Implementation Guide

External Component Selection

For optimal performance with the FAN53611AUC11X:

• Inductor: 1 H (XAL6060-102ME or equivalent)
• Input Capacitor: 4.7 F X5R ceramic (0805 size recommended)
• Output Capacitor: 10 F X5R ceramic (0603 or 0805 size)

Layout Best Practices

• Minimize loop area for SW node to reduce EMI
• Place input capacitor within 1mm of VIN pin
• Use ground plane for thermal dissipation

Comparative Advantages

When benchmarked against competing solutions, the FAN53611AUC11X offers:

Feature	FAN53611AUC11X	Typical Competitor
Switching Frequency	6MHz	2-3MHz
Footprint	1.08mm	4-9mm
Quiescent Current	22 A	30-50 A
Load Step Response	<50 s	100-200 s

Application Circuits

Standard Implementation

The typical application circuit requires only 4 external components, making it ideal for space-constrained designs. The high 6MHz switching frequency allows for extremely compact inductor and capacitor selection.

Battery-Powered Systems

For portable applications, the FAN53611AUC11X's 2.3V minimum input voltage enables operation from nearly discharged single-cell Li-Ion batteries, while its 22 A quiescent current maximizes battery life.

Reliability and Compliance

• 100% production tested for key parameters
• ESD protection: 2kV HBM
• RoHS compliant and halogen-free
• Manufactured in IATF 16949 certified facilities

Purchasing Information

As this device is currently in Last Time Buy status, we recommend:

• Immediate orders for production quantities
• Evaluation of drop-in alternatives if needed
• Consideration of the FAN53620 series for new designs

For engineers requiring a high-efficiency, ultra-compact power solution, the FAN53611AUC11X delivers unmatched performance in its class. Its combination of 6MHz operation, 1A output capability, and WLCSP packaging makes it the ideal choice for smartphones, wearables, IoT devices, and other space-constrained applications.