1

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FN6462.0

PX3511A, PX3511B

Advanced Synchronous Rectified Buck

MOSFET Drivers with Protection Features

The PX3511A and PX3511B are high frequency MOSFET

drivers specifically designed to drive upper and lower power

N-Channel MOSFETs in a synchronous rectified buck

converter topology. These drivers combined with the

ISL6595 Digital Multi-Phase Buck PWM controller and

N-Channel MOSFETs form a complete core-voltage

regulator solution for advanced microprocessors.

The PX3511A drives the upper gate to 12V, while the lower

gate can be independently driven over a range from 5V to

12V. The PX3511B drives both upper and lower gates over a

range of 5V to 12V. This drive-voltage provides the flexibility

necessary to optimize applications involving trade-offs

between gate charge and conduction losses.

An adaptive zero shoot-through protection is integrated to

prevent both the upper and lower MOSFETs from conducting

simultaneously and to minimize the dead time. These

products add an overvoltage protection feature operational

before VCC exceeds its turn-on threshold, at which the

PHASE node is connected to the gate of the low side

MOSFET (LGATE). The output voltage of the converter is

then limited by the threshold of the low side MOSFET, which

provides some protection to the microprocessor if the upper

MOSFET(s) is shorted during initial start-up.

These drivers also feature a three-state PWM input which,

working together with Intersil’s multi-phase PWM controllers,

prevents a negative transient on the output voltage when the

output is shut down. This feature eliminates the Schottky

diode that is used in some systems for protecting the load

from reversed output voltage events.

Features

• Dual MOSFET Drives for Synchronous Rectified Bridge

• Adjustable Gate Voltage (5V to 12V) for Optimal Efficiency

• 36V Internal Bootstrap Schottky Diode

• Bootstrap Capacitor Overcharging Prevention

• Supports High Switching Frequency (up to 2MHz)

- 3A Sinking Current Capability

- Fast Rise/Fall Times and Low Propagation Delays

• Three-State PWM Input for Output Stage Shutdown

• Three-State PWM Input Hysteresis for Applications With

Power Sequencing Requirement

• Pre-POR Overvoltage Protection

• VCC Undervoltage Protection

• Expandable Bottom Copper Pad for Enhanced Heat

Sinking

• Dual Flat No-Lead (DFN) Package

- Near Chip-Scale Package Footprint; Improves PCB

Efficiency and Thinner in Profile

• Pb-Free Plus Anneal Available (RoHS Compliant)

Applications

• Core Regulators for Intel® and AMD® Microprocessors

• High Current DC/DC Converters

• High Frequency and High Efficiency VRM and VRD

Related Literature

• Technical Brief TB363 “Guidelines for Handling and

Processing Moisture Sensitive Surface Mount Devices

(SMDs)”

• Technical Brief TB417 for Power Train Design, Layout

Guidelines, and Feedback Compensation Design

Data Sheet

February 26, 2007

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. 2006. All Rights Reserved

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