ISL6622B Datasheet, PDF (1/11 Pages) Intersil Corporation – VR11.1 Compatible Synchronous Rectified Buck MOSFET Drivers

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Data Sheet
March 19, 2009
ISL6622B
FN6602.1
VR11.1 Compatible Synchronous
Rectified Buck MOSFET Drivers
The ISL6622B is a high frequency MOSFET driver designed
to drive upper and lower power N-Channel MOSFETs in a
synchronous rectified buck converter topology. The advanced
PWM protocol of ISL6622B is specifically designed to work
with Intersil VR11.1 controllers and combined with
N-Channel MOSFETs, form a complete core-voltage regulator
solution for advanced microprocessors. When ISL6622B
detects a PSI PWM protocol sent by an Intersil VR11.1
controller, it activates Diode Emulation (DE) operation;
otherwise, it operates in normal Continuous Conduction
Mode (CCM) PWM mode.
In the 8 Ld SOIC package, the ISL6622B drives the upper
gate to 12V while the lower drive voltage is fixed at 5.75V. The
10 Ld DFN part offers more flexibility: the upper gate can be
driven from 5V to 12V via the UVCC pin, while the lower gate
has a resistor-selectable drive voltage of 5.75V, 6.75V, and
7.75V (typically). This provides the flexibility necessary to
optimize applications involving trade-offs between gate
charge and conduction losses.
To further enhance light load efficiency, the ISL6622B
enables diode emulation operation during PSI mode. This
allows for Discontinuous Conduction Mode (DCM) operation
by detecting when the inductor current reaches zero and
subsequently turning off the low side MOSFET to prevent it
from sinking current.
An advanced adaptive shoot-through protection is integrated
to prevent both the upper and lower MOSFETs from
conducting simultaneously and to minimize dead time. The
ISL6622B has a 20kΩ integrated high-side MOSFET
gate-to-source resistor to prevent self turn-on due to high
input bus dV/dt. This driver also has an overvoltage
protection feature operational while VCC is below the POR
threshold: the PHASE node is connected to the gate of the
low side MOSFET (LGATE) via a 10kΩ resistor, limiting the
output voltage of the converter close to the gate threshold of
the low side MOSFET, dependent on the current being
shunted, which provides some protection to the load should
the upper MOSFET(s) be shorted prior to start-up.
Features
• Dual MOSFET Drives for Synchronous Rectified Bridge
• Advanced Adaptive Zero Shoot-Through Protection
• Integrated LDO with Selectable Lower Gate Drive Voltage
for Light Load Efficiency Optimization
• 36V Internal Bootstrap Diode
• Advanced PWM Protocol (Patent Pending) to Support PSI
Operation
• Diode Emulation for Enhanced Light Load Efficiency
• Bootstrap Capacitor Overcharging Prevention
• Supports High Switching Frequency
- 3A Sinking Current Capability
- Fast Rise/Fall Times and Low Propagation Delays
• Integrated UGATE-to-PHASE Resistor for Increased
Upper MOSFET Input Bus High dV/dt Immunity
• Pre-POR Overvoltage Protection at Start-Up and
Shutdown
• Dual Flat No-Lead (DFN) Package
- Near Chip-Scale Package Footprint; Improves PCB
Efficiency and Thinner in Profile
- Bottom Copper Pad for Enhanced Heat Sinking
• Pb-Free (RoHS Compliant)
Applications
• High Light-Load Efficiency Voltage Regulators
• Core Regulators for Advanced 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 “Designing Stable Compensation
Networks for Single Phase Voltage Mode Buck
Regulators” for Power Train Design, Layout Guidelines,
and Feedback Compensation Design
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CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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