2.5A Regulator with Integrated High-side MOSFET for Synchronous Buck or Boost Buck Converter

The ISL85403 is a 40V, 2.5A synchronous buck or boost buck controller with a high-side MOSFET and low-side driver integrated. In buck mode, the ISL85403 supports a wide input range of 3V to 40V. In boost-buck mode, the input range can be extended down to 2.5V and output regulation can be maintained when VIN drops below VOUT, enabling sensitive electronics to remain on in low input voltage conditions.

Features
• Buck mode: input voltage range 3V to 40V (refer to “Input Voltage” on page 15 for more details)
• Boost mode expands operating input voltage lower than 2.5V (refer to “Input Voltage” on page 15 for more details)
• Selectable forced PWM mode or PFM mode
• 300µA IC quiescent current (PFM, no load); 180µA input quiescent current (PFM, no load, VOUT tied to AUXVCC)
• Less than 5µA (MAX) shutdown input current (IC disabled)
• Operational topologies
    - Synchronous buck
    - Non-synchronous buck
    - Two-stage boost buck
    - Non-inverting single inductor buck boost
• Programmable frequency from 200kHz to 2.2MHz and frequency synchronization capability
• ±1% tight voltage regulation accuracy
• Reliable overcurrent protection
    - Temperature compensated current sense
    - Cycle-by-cycle current limiting with frequency foldback
    - Hiccup mode for worst case short condition
• 20 Ld 4x4 QFN package
• Pb-free (RoHS compliant)

Applications
• General purpose
• 24V bus power
• Battery power
• Point-of-load
• Embedded processor and I/O supplies