The ISL6545 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 integrates the control, gate drivers, output

adjustment, monitoring and protection functions into a single

8 Ld SOIC or 10 Ld DFN package.

The ISL6545 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 rDS(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.

特性 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