The ISL6611A utilizes Intersil’s proprietary Phase Doubler

scheme to modulate two-phase power trains with single

PWM input. It doubles the number of phases that Intersil’s

ISL63xx multiphase controllers can support. At the same

time, the PWM line can be pulled high to disable the

corresponding phase or higher phase(s) when the enable

pin (EN_PH) is pulled low. This simplifies the phase

shedding implementation. For layout simplicity and

improving system performance, the device integrates two 5V

drivers (ISL6609) and current balance function.

The ISL6611A is designed to minimize the number of analog

signals interfacing between the controller and drivers in high

phase count and scalable applications. The common COMP

signal, which is usually seen with conventional cascaded

configuration, is not required; this improves noise immunity

and simplifies the layout. Furthermore, the ISL6611A

provides low part count and a low cost advantage over the

conventional cascaded technique.

The IC is biased by a single low voltage supply (5V),

minimizing driver switching losses in high MOSFET gate

capacitance and high switching frequency applications.

Bootstrapping of the upper gate driver is implemented via an

internal low forward drop 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 ISL6611A features 4A typical sink current for the lower

gate driver, enhancing the lower MOSFET gate hold-down

capability during PHASE node rising edge, preventing power

loss caused by the self turn-on of the lower MOSFET due to

the high dV/dt of the switching node.

The ISL6611A also features an input that recognizes a

high-impedance state, working together with Intersil

multiphase PWM controllers to prevent negative transients

on the controlled output voltage when operation is

suspended. This feature eliminates the need for the Schottky

diode that may be utilized in a power system to protect the

load from negative output voltage damage.

In addition, the ISL6611A’s bootstrap function is designed to

prevent the BOOT capacitor from overcharging, should

excessively large negative swings occur at the transitions of

the PHASE node.

Features

? Proprietary Phase Doubler Scheme with Phase Shedding

Function (Patent Pending)

- Enhanced Light to Full Load Efficiency

? Patented Current Balancing with rDS(ON) Current Sensing

and Adjustable Gain

? Quad MOSFET Drives for Two Synchronous Rectified

Bridge with Single PWM Input

? Channel Synchronization and Interleaving Options

? Adaptive Zero Shoot-Through Protection

? 0.4Ω On-Resistance and 4A Sink Current Capability

? 36V Internal Bootstrap Schottky Diode

? Bootstrap Capacitor Overcharging Prevention (ISL6611A)

? Supports High Switching Frequency (Up to 1MHz)

- Fast Output Rise and Fall

? Tri-State PWM Input for Output Stage Shutdown

? Phase Enable Input and PWM Forced High Output to

Interface with Intersil’s Controller for Phase Shedding

? QFN Package

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

No Leads-Product Outline

- Near Chip-Scale Package Footprint; Improves PCB

Utilization, Thinner Profile

- Pb-Free (RoHS Compliant)

Applications

? High Current Low Voltage DC/DC Converters

? High Frequency and High Efficiency VRM and VRD

? High Phase Count and Phase Shedding Applications