1
®
FN6601.2
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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ISL6622A
VR11.1 Compatible Synchronous
Rectified Buck MOSFET Drivers
The ISL6622A 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 ISL6622A 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 ISL6622A
detects a PSI
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 ISL6622A drives the upper
gate to 12V while the lower get can be driven from 5V to 12V.
The 10 Ld DFN part allows for more flexibility. The upper gate
can be driven from 5V to 12V using the UVCC pin and the
lower gate can also be driven from 5V to 12V using the LVCC
pin. This provides the flexibility necessary to optimize
applications involving trade-offs between gate charge and
conduction losses.
To further enhance light load efficiency, the ISL6622A
enables diode emulation operation during PSI
mode. This
allows Discontinuous Conduction Mode (DCM) 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
ISL6622A has a 20kΩ integrated high-side gate-to-source
resistor to prevent self turn-on due to high input bus dV/dt.
This driver adds an overvoltage protection feature
operational while VCC is below its 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) become shorted.
Features
• Dual MOSFET Drives for Synchronous Rectified Bridge
• Advanced Adaptive Zero Shoot-Through Protection
• 36V Internal Bootstrap Schottky Diode
• 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
• Advanced PWM Protocol (Patent Pending) to Support PSI
Mode, Diode Emulation, Three-State Operation
• Pre-POR Overvoltage Protection for Start-up and
Shutdown
• 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 (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
Data Sheet March 19, 2009
