ISL8120

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 rDS(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 ISL8120s 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.