ISL6608 Datasheet, PDF (1/11 Pages) Intersil Corporation – Synchronous Rectified MOSFET Driver

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Data Sheet
March 2004
ISL6608
FN9140.1
Synchronous Rectified MOSFET Driver
with Pre-Biased Load Startup Capability
The ISL6608 is a high frequency, MOSFET driver optimized
to drive two N-Channel power MOSFETs in a synchronous-
rectified buck converter topology. This driver combined with
an Intersil HIP63xx or ISL65xx Multi-Phase Buck PWM
controller forms a complete single-stage core-voltage
regulator solution with high efficiency performance at high
switching frequency for advanced microprocessors.
The IC is biased by a single low voltage supply (5V) and
minimizes gate drive losses due to MOSFET gate charge at
high switching frequency applications. Each driver is capable
of driving a 3000pF load with a low propagation delay and
less than 10ns transition time. This product implements
bootstrapping on the upper gate with an internal bootstrap
Schottky diode, reducing implementation cost, complexity,
and allowing the use of higher performance, cost effective
N-Channel MOSFETs. Adaptive shoot-through protection is
integrated to prevent both MOSFETs from conducting
simultaneously.
The ISL6608 features 4A sink current for the lower gate
driver, which is capable of holding the lower MOSFET gate
during the Phase node rising edge to prevent shoot-through
power loss caused by the high dv/dt of the Phase node.
The ISL6608 also features a Three-State PWM input which,
working together with Intersil multi-phase PWM controllers,
will prevent a negative transient on the output voltage when
the output is shut down. This feature eliminates the Schottky
diode that is usually seen in a microprocessor power system
for protecting the microprocessor from reversed output
voltage events.
A diode emulation feature is integrated in the ISL6608 to
enhance converter efficiency at light load conditions. Diode
emulation also prevents a negative transient when starting
up with a pre-biased voltage on the output. When diode
emulation is enabled, the driver allows discontinuous
conduction mode by detecting when the inductor current
reaches zero and subsequently turns off the low side
MOSFET, which prevents the output from sinking current
and producing a negative transient on a pre-biased output
(see Figures 6 and 7 on page 7).
Features
• Dual MOSFET Drives for Synchronous Rectified Bridge
• Adaptive Shoot-Through Protection
• 0.5Ω On-Resistance and 4A Sink Current Capability
• Supports High Switching Frequency up to 2MHz
- Fast Output Rise/Fall Time and Low Propagation Delay
• Three-State PWM Input for Power Stage Shutdown
• Internal Bootstrap Schottky Diode
• Low Bias Supply Current (5V, 80µA)
• Diode Emulation for Enhanced Light Load Efficiency and
Pre-Biased Startup Applications
• VCC POR (Power-On-Reset) Feature Integrated
• Low Three-State Shutdown Holdoff Time (Typically 160ns)
• Pin-to-Pin Compatible with ISL6605
• 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 Available as an Option
Applications
• Core Voltage Supplies for FPGAs and PowerPC
Microprocessors
• Point-Of-Load Modules with Pre-Biased Start-Up
Requirements
• High Frequency and High Current DC-DC Converters
Related Literature
• Technical Brief TB363 “Guidelines for Handling and
Processing Moisture Sensitive Surface Mount Devices”
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CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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