1

®

FN9066.5

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

1-888-INTERSIL or 1-888-468-3774

Copyright © Intersil Americas Inc. 2003-2006. All Rights Reserved.

All other trademarks mentioned are the property of their respective owners.

ISL6551

ZVS Full Bridge PWM Controller

The ISL6551 is a zero voltage switching (ZVS) full-bridge

PWM controller designed for isolated power systems. This

part implements a unique control algorithm for fixed-

frequency ZVS current mode control, yielding high efficiency

with low EMI. The two lower drivers are PWM-controlled on

the trailing edge and employ resonant delay while the two

upper drivers are driven at a fixed 50% duty cycle.

28-lead SOIC packages to yield a complete and

sophisticated power supply solution. Control features include

programmable soft-start for controlled start-up,

programmable resonant delay for zero voltage switching,

programmable leading edge blanking to prevent false

triggering of the PWM comparator due to the leading edge

spike of the current ramp, adjustable ramp for slope

compensation, drive signals for implementing synchronous

rectification in high output current, ultra high efficiency

applications, and current share support for paralleling up to

10 units, which helps achieve higher reliability and

availability as well as better thermal management. Protective

features include adjustable cycle-by-cycle peak current

limiting for overcurrent protection, fast short-circuit protection

(in hiccup mode), a latching shutdown input to turn off the IC

completely on output overvoltage conditions or other

extreme and undesirable faults, a non-latching enable input

to accept an enable command when monitoring the input

voltage and thermal condition of a converter, and VDD under

voltage lockout with hysteresis. Additionally, the ISL6551

includes high current high-side and low-side totem-pole

drivers to avoid additional external drivers for moderate gate

capacitance (up to 1.6nF at 1MHz) applications, an

uncommitted high bandwidth (10MHz) error amplifier for

feedback loop compensation, a precision bandgap reference

with ±1.5% (ISL6551AB) or ±1% (ISL6551IB) tolerance over

recommended operating conditions, and a ±5% “in

regulation” monitor.

In addition to the ISL6551, other external elements such as

transformers, pulse transformers, capacitors, inductors and

Schottky or synchronous rectifiers are required for a

complete power supply solution. A detailed 200W telecom

power supply reference design using the ISL6551 with

companion Intersil ICs, Supervisor And Monitor ISL6550 and

Half-bridge Driver HIP2100, is presented in Application Note

AN1002.

In addition, the ISL6551 can also be designed in push-pull

converters using all of the features except the two upper

drivers and adjustable resonant delay features.

Features

• High Speed PWM (up to 1MHz) for ZVS Full Bridge

Control

• Current Mode Control Compatible

• High Current High-Side and Low-Side Totem-Pole Drivers

• Adjustable Resonant Delay for ZVS

• 10MHz Error Amplifier Bandwidth

• Programmable Soft-Start

• Precision Bandgap Reference

• Latching Shutdown Input

• Non-latching Enable Input

• Adjustable Leading Edge Blanking

• Adjustable Dead Time Control

• Adjustable Ramp for Slope Compensation

• Fast Short-Circuit Protection (Hiccup Mode)

• Adjustable Cycle-by-Cycle Peak Current Limiting

• Drive Signals to Implement Synchronous Rectification

• VDD Under-voltage Lockout

• Current Share Support

• ±5% “In Regulation” Indication

• QFN Package:

- Compliant to JEDEC PUB95 MO-220 QFN - Quad Flat

No Leads - Package Outline

- Near Chip Scale Package footprint, which improves

PCB efficiency and has a thinner profile

• Pb-Free Plus Anneal Available (RoHS Compliant)

Applications

• Full-Bridge and Push-Pull Converters

• Power Supplies for Off-line and Telecom/Datacom

• Power Supplies for High End Microprocessors and

Servers

Data Sheet

January 3, 2006