ISL8120
Dual/n-Phase Buck PWM Controller with Integrated Drivers

Key Features

• Wide VIN Range Operation: 3V to 22V
• VCC Operation from 3V to 5.60V
• Fast Transient Response
• 80MHz Bandwidth Error Amplifier
• Voltage-Mode PWM Leading-edge Modulation Control
• Voltage Feed-forward
• Dual Channel 5V High Speed 4A MOSFET Gate Drivers
• Internal Bootstrap Diodes
• Internal Linear Regulator Provides a 5.4V Bias from VIN
• External Soft-Start Ramp Reference Input for DDR/Tracking Applications
• Excellent Output Voltage Regulation
• 0.6V ±0.6%/±0.9% Internal Reference Over Commercial/Industrial Temperature
• True Differential Remote Voltage Sensing
• Oscillator Programmable from 150kHz to 1.5MHz
• Frequency Synchronization
• Scale for 1-, 2-, 3-, 4-, 6-, up to 12- Phase with Single Output
• Excellent Phase Current Balancing
• Programmable Phase Shift Between the 2 Phases Controlled by the ISL8120 and Programmable Phase Shift for Clockout Signal
• Interleaving Operation Results in Minimum Input RMS Current and Minimum Output Ripple Current
• Fault Hand Shake Capability for High System Reliability
• Overcurrent Protection
• DCR, r_DS(ON), or Precision Resistor Current Sensing
• Independent and Average Phase Current OCP
• Output Overvoltage and Undervoltage Protections
• Programmable Phase Shift in Dual Mode Operation
• Digital Soft-Start with Pre-Charged Output Start-up Capability
• Power-Good Indication
• Dual Independent Channel Enable Inputs with Precision Voltage Monitor and Voltage Feed-forward Capability
• Programmable Input Voltage POR and its Hysteresis with a Resistor Divider at EN Input
• Over-Temperature Protection
• Pre-Power-On-Reset Overvoltage Protection Option
• 32 Ld 5x5 QFN Package - Near Chip-Scale Footprint
• Enhanced Thermal Performance for MHz Applications
• Pb-free (RoHS compliant)

Description

The ISL8120 integrates two voltage-mode synchronous buck PWM controllers to control a dual independent voltage regulator or a 2-phase single output regulator. It has PLL circuits and can output a phase-shift-programmable clock signal for the system to be expanded to 3-, 4-, 6-, 12- phases with desired interleaving phase shift. It also integrates current sharing control for the power module to operate in parallel, which offers high system flexibility.

It has voltage feed forward compensation to maintain a constant loop gain for optimal transient response, especially for applications with a wide input voltage range. Its integrated high speed MOSFET drivers and multi-feature functions provide complete control and protection for a 2/n-phase synchronous buck converter, dual independent regulators, or DDR tracking applications (VDDQ and VTT outputs).

The output voltage of a ISL8120-based converter can be precisely regulated to as low as the internal reference voltage 0.6V, with a system accuracy of ±0.6% over commercial temperature and line load variations. Channel 2 can track an external ramp signal for DDR/tracking applications.

The ISL8120 integrates an internal linear regulator, which generates VCC from input rail for applications with only one single supply rail. The internal oscillator is adjustable from 150kHz to 1.5MHz, and is able to track an external clock signal for frequency synchronization and phase paralleling applications. The integrated Pre-Biased Digital Soft-Start, Differential Remote Sensing Amplifier, and Programmable Input Voltage POR features enhance the value of ISL8120.

The ISL8120 protects against overcurrent conditions by inhibiting the PWM operation while monitoring the current with r_DS(ON) of the lower MOSFET, DCR of the output inductor, or a precision resistor. It also has a PRE-POR Overvoltage Protection option, which provides some protection to the load device if the upper MOSFET(s) is shorted. See "PRE-POR Overvoltage Protection (PRE-POROVP)" on page 25 for details.

The ISL8120's Fault Hand Shake feature protects any channel from overloading/stressing due to system faults or phase failure. The undervoltage fault protection features are also designed to prevent a negative transient on the output voltage during falling down. This eliminates the Schottky diode that is used in some systems for protecting the load device from reversed output voltage damage.

Applications

• Power Supply for Datacom/Telecom and POL
• Paralleling Power Module
• Wide and Narrow Input Voltage Range Buck Regulators
• DDR I and II Applications
• High Current Density Power Supplies
• Multiple Outputs VRM and VRD