Overview

The ISL85403 is a 40V, 2. 5A synchronous buck or boost-buck controller with an integrated high-side MOSFET and low-side driver. 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. The ISL85403 has a flexible selection of Forced PWM mode and PFM mode. In PFM mode, the quiescent input current is as low as 180µA (AUXVCC connected to VOUT). The load boundary between PFM and PWM can be programmed to cover wide applications. The low-side driver can either be used to drive an external low-side MOSFET for a synchronous buck or left unused for a standard non-synchronous buck. The low-side driver can also be used to drive a boost converter as a preregulator followed by a buck controlled by the same IC, which greatly expands the operating input voltage range down to 2. 5V or lower. ISL85403 offers robust current protection. It uses peak current mode control with cycle-by-cycle current limiting. It is implemented with frequency foldback under current limit condition; also, the hiccup overcurrent mode ensures reliable operations under harsh short conditions. The ISL85403 has comprehensive protections against various faults including overvoltage and over-temperature protection.

ISL85403 Functional Diagram
ISL85403 Functional Diagram
  • Buck mode: input voltage range 3V to 40V
  • Boost mode expands operating input voltage lower than 2.5V
  • 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

Documentation

Design & Development

Software & Tools
iSim:PE Offline Simulation Tool
iSim Personal Edition (iSim:PE) speeds the design cycle and reduces risk early in any project, identifying parts that can be used in current as well as next-generation designs.
Downloads
ISL85403 Buck Regulator iSim:PE ModelISL85403 Boost-Buck Regulator iSim:PE ModelISL85403 Buck-Boost Regulator iSim:PE Model
 Simulator Renesas
1 item
ISL85403DEMO1Z Regulator with Integrated MOSFET Demo Board

ISL85403DEMO1Z

Demonstration
Learn More

Synchronous Buck Demo Board with 7V to 40V Input Range, 5V 2.5A Output

The ISL85403DEMO1Z demonstration board allows for quick evaluation of the ISL85403 synchronous buck or boost-buck controller in the synchronous buck configuration. It...

Featured Documents:
ISL85403DEMO1Z User Guide
ISL85403EVAL2Z Regulator with Integrated MOSFET Eval Board

ISL85403EVAL2Z

Evaluation
Learn More

Buck-Boost EVB with 8V to 40V Input Range, 12V 1A Output

The ISL85403EVAL2Z board allows for quick evaluation of the ISL85403 synchronous buck or boost-buck controller in the non-inverting buck-boost configuration. It is a...

Featured Documents:
ISL85403EVAL2Z User Guide
Buck-Boost Last Gasp Power Supply for Energy Meters Reference Design Board

CN274-BBGASPPOCZ

Reference Designs
Learn More

Buck-Boost Last Gasp Power Supply for Energy Meter Reference Design

In this Reference Design, a supercapacitor is used as a backup power supply. The board allows for quick evaluation of the ISL85403 buck/boost controller in the...

Featured Documents:
Buck-Boost Last Gasp Power Supply for Energy Meter Design Files
CN274-BBGASPPOCZ Power Supply with Supercapacitor User's Manual
Available on Lab on the Cloud
Use our PC-based GUI to instantly start configuring and testing designs in our virtual lab, no physical board needed.
Launch Lab on the Cloud

ECAD Models

Schematic symbols, PCB footprints, and 3D CAD models from SamacSys can be found by clicking on products in the Product Options table. If a symbol or model isn't available, it can be requested directly from the website.

Explore ECAD Models
Diagram of ECAD Models

Product Options

    Processing table
    PLP
    Pkg. Type
    Carrier Type
    Moisture Sensitivity Level (MSL)
    Price (USD) | 1ku
    Buy / Sample
    Part Number
    ISL85403FRZ
    circleActive
    memory
    spa
    view_in_ar
    Samples Available
    		 2033 Dec QFN Tray 3 Get Samples,
    ISL85403FRZ-T
    circleActive
    memory
    spa
    view_in_ar
    		2033 Dec QFN Reel 3
    ISL85403FRZ-TK
    circleActive
    memory
    spa
    view_in_ar
    		2033 Dec QFN Reel 3 2.325
    Parametric Table tips

    Tips for Using This Parametric Table:

    • Hide Filters button in header: Collapse or expands filters
    • Column sort buttons in header: Sort Column alphabetically / numerically descending or ascending
    • Reset button in header: Reset all filters to the page default
    • Full Screen button in header: Expand the table to full screen view (user must close out of full screen before they can interact with rest of page)
    • Export button in header: Export the filtered results of the table to an Excel document
    • Filter parts search bar in header: Type to filter table results by part number
    • Hide column button in column headers: Select to hide columns in table
    • AND / OR toggle switches in header: Toggles the logic of this particular filter to be “AND” or “OR” logic for filtering results
    • Multiselect checkboxes at beginning of each row in table: Select these checkboxes to compare products against each other
    • Document icon next to product name in row: View the featured document for this product
    • Chip icon next to the right of the document icon in row: View the block diagram for this product
    • Cart icon to the right of the chip icon: Indicates that samples are available for this product