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The ISL6545, ISL6545A makes simple work out of implementing a complete control and protection scheme for a DC/DC stepdown converter driving N-Channel MOSFETs in a synchronous buck topology. Since it can work with either 5V or 12V supplies, this one IC can be used in a wide variety of applications within a system. The ISL6545, ISL6545A (hereafter referred to as "ISL6545x", except as needed) integrates the control, gate drivers, output adjustment, monitoring and protection functions into a single 8 Ld SOIC or 10 Ld DFN package.

The ISL6545x provides single feedback loop, voltage-mode control with fast transient response. The output voltage can be precisely regulated to as low as 0.6V, with a maximum tolerance of ±1.0% over-temperature and line voltage variations. A selectable fixed frequency oscillator (ISL6545 for 300kHz; ISL6545A for 600kHz) reduces design complexity, while balancing typical application cost and efficiency.

The error amplifier features a 20MHz gain-bandwidth product and 9V/µs slew rate which enables high converter bandwidth for fast transient performance. The resulting PWM duty cycles range from 0% to 100%.

Protection from overcurrent conditions is provided by monitoring the r_DS(ON) of the lower MOSFET to inhibit PWM operation appropriately. This approach simplifies the implementation and improves efficiency by eliminating the need for a current sense resistor.

Key Features

• Operates from +5V or +12V Supply Voltage (for bias)
  • 1.0V to 12V VIN Input Range (up to 20V possible with restrictions; see Input Voltage Considerations)
  • 0.6V to VIN Output Range
  • Integrated Gate Drivers use VCC (5V to 12V)
  • 0.6V Internal Reference; ±1.0% tolerance
• Simple Single-Loop Control Design
  • Voltage-Mode PWM Control
  • Drives N-Channel MOSFETs
  • Traditional Dual Edge Modulator
• Fast Transient Response
  • High-Bandwidth Error Amplifier
  • Full 0% to 100% Duty Cycle
• Lossless, Programmable Overcurrent Protection
  • Uses Lower MOSFET's rDS(ON)
• Small Converter Size in 8 Ld SOIC or 10 Ld DFN
  • 300kHz or 600kHz Fixed Frequency Oscillator
  • Fixed Internal Soft-Start, Capable into a Pre-biased Load
  • Integrated Boot Diode
  • Enable/Shutdown Function on COMP/SD Pin
  • Output Current Sourcing and Sinking
• Pb-Free (RoHS Compliant)

Applications

• Power Supplies for Microprocessors or Peripherals
  • PCs, Embedded Controllers, Memory Supplies
  • DSP and Core Communications Processor Supplies
• Subsystem Power Supplies
  • PCI, AGP; Graphics Cards; Digital TV
  • SSTL-2 and DDR/DDR2/DDR3 SDRAM Bus Termination Supply
• Cable Modems, Set Top Boxes, and DSL Modems
• Industrial Power Supplies; General Purpose Supplies
• 5V or 12V-Input DC/DC Regulators
• Low-Voltage Distributed Power Supplies