The ISL9440, ISL9440A and ISL9441 are quad-output synchronous buck controllers that integrate 3 PWM controllers and 1 low drop-out linear regulator controller, which are full featured and designed to provide multi-rail power for use in products such as cable and satellite set-top boxes, VoIP gateways, cable modems, and other home connectivity products as well as a variety of industrial and general purpose applications. Each output is adjustable down to 0.8V. The PWMs are synchronized at 180° out of phase thus reducing the RMS input current and ripple voltage. The ISL9440, ISL9440A and ISL9441 offer internal soft-start, independent enable inputs for ease of supply rail sequencing, and integrated UV/OV/OC/OT protections in a space conscious 5mm x 5mm QFN package. The ISL9440 and ISL9440A offers an early warning function to output a logic signal to warn the system to back up data when the input voltage falls below a certain level. The ISL9440, ISL9440A and ISL9441 are utilize internal loop compensation to keep minimum peripheral components for compact design and a low total solution cost. These devices are implemented with current mode control with feed forward to cover various applications even with fixed internal compensations. The table below shows the difference in terms of ISL9440, ISL9440A and ISL9441 features.

ISL9440 YES 300
ISL9440A YES 600
ISL9441 NO 300


  • Three integrated synchronous buck PWM controllers
  • Internal bootstrap diodes
  • Internal compensation
  • Internal soft-start
  • Independent control for each regulator and programmable output voltages; independent enable/shutdown
  • Fixed Switching Frequency: 300kHz (ISL9440, ISL9441); 600kHz (ISL9440A)
  • Adaptive shoot through protection on all synchronous buck controllers
  • Independently programmable voltage outputs
  • Out-of-phase switching to reduce input capacitance (0°/180°/0°)
  • No external current sense resistor
  • Uses lower MOSFET's rDS(ON)
  • Current mode controller with voltage feed forward
  • Complete protection
  • Overcurrent, overvoltage, undervoltage lockout, over-temperature
  • Cycle-by-cycle current limiting
  • Wide input voltage range
  • Input rail powers VIN Pin: 5.6V to 24V
  • Input rail powers VCC_5V Pin (VIN tied to VCC_5V, for 5V input applications): 4.5V to 5.6V
  • Early warning (ISL9440, ISL9440A) on input voltage failure
  • Integrated reset function (ISL9440, ISL9440A)
  • Pb-free (RoHS compliant)


  • Satellite and Cable Set-Top Boxes
  • Cable Modems
  • VoX Gateway Devices
  • NAS/SAN Devices

Design & Development

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Software & Tool Pages

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iSim:PE Offline Simulation TooliSim 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: Simulator Renesas

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