Dual/n-Phase Buck PWM Controller with Integrated Drivers ISL8126 Features The ISL8126 integrates two voltage-mode PWM leading-edge Wide V Range Operation: 3V to 26.5V IN modulation control with input feed-forward synchronous buck - VCC Operation from 3V to 5.60V PWM controllers to control dual independent voltage Excellent Output Voltage Regulation: 0.6V Internal regulators or a 2-phase single output regulator. It also Reference integrates current sharing control for the power module to operate in parallel, which offers high system flexibility. Frequency Synchronization with Programmable Phase Delay up to 12-Phase Applications The ISL8126 integrates an internal linear regulator, which Fault Spreading Capability for High System Reliability generates ICs bias voltages for applications with only one single supply rail. The internal oscillator is adjustable from Digital Soft-Start with Pre-Charged Output Start-up 150kHz to 1.5MHz, and is able to synchronize to an external Capability clock signal for frequency synchronization and phase Dual Independent Channel Enable Inputs with Precision paralleling applications. Its PLL circuit can output a Voltage Monitor and Voltage Feed-forward Capability phase-shift-programmable clock signal for the system to be - Programmable Input Voltage POR and its Hysteresis with expanded to 3-, 4-, 6-, 12- phases with desired interleaving a Resistor Divider at EN Input phase shift. Extensive Circuit Protection Functions: Output Overvoltage, The ISL8126s Fault Spreading feature protects any channel Undervoltage, Overcurrent Protection, Over-temperature and from overloading/stressing due to system faults or phase Pre-Power-On-Reset Overvoltage Protection Option failure. The undervoltage fault protection features are also designed to prevent a negative transient on the output voltage Applications during falling down. This eliminates the Schottky diode that is used in some systems for protecting the load device from Power Supply for Datacom/Telecom and POL reversed output voltage damage. Paralleling Power Module Table 1 summarizes the differences between ISL8126 and Wide and Narrow Input Voltage Range Buck Regulators ISL8126A. TABLE 1. Related Literature REFERENCE VOLTAGE VSEN1+ to VSEN1- INPUT Technical Brief TB389 PCB Land Pattern Design and DEVICES (V) IMPEDANCE Surface Mount Guidelines for QFN Packages ISL8126 0.6 500k ISL8126A 0.7 >2M August 16, 2012 CAUTION: These devices are sensitive to electrostatic discharge follow proper IC Handling Procedures. 1 1-888-INTERSIL or 1-888-468-3774 Copyright Intersil Americas Inc. 2011, 2012. All Rights Reserved FN7892.1 Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries. All other trademarks mentioned are the property of their respective owners.ISL8126 Pin Configuration ISL8126 (32 LD QFN) TOP VIEW 32 31 30 29 28 27 26 25 COMP1 1 24 UGATE1 ISET PHASE1 2 23 ISHARE 3 22 LGATE1 PVCC EN/VFF1 4 21 33 GND FSYNC 5 20 LGATE2 EN/VFF2 6 19 PHASE2 CLKOUT/REFIN UGATE2 7 18 PGOOD BOOT2 8 17 9 1011 12 13 1415 16 Functional Pin Descriptions PIN NUMBER SYMBOL DESCRIPTION 1, 9 COMP1, COMP2 These pins are the error amplifier outputs. They should be connected to FB1, FB2 pins through desired compensation networks when both channels are operating independently. When VSEN1-, VSEN2- are pulled within 400mV of VCC, the corresponding error amplifier is disabled and its output (COMP pin) is high impedance. Thus, in multiphase operations, all other SLAVE phases COMP pins can tie to the MASTER phases COMP1 pin (1st phase), which modulates each phases PWM pulse with a single voltage feedback loop. While the error amplifier is not disabled, an independent compensation network is required for each cascaded IC. 2 ISET This pin along with ISHARE pin are used for multiple ISL8126 current sharing purposes. When in 2-phase mode (VSEN2- pulled within 400mV of VCC), this pin sources a current which is a combination of 15A constant offset current, current correction current (more details on Current Share Control in Multiphase Single Output with Shared COMP Voltage on page 31), and the average of both sensed channel currents. When in Dual-output mode, this pin sources a current, which is a combination of 15A constant offset current, current correction current, and Channel 1s sensed current. The current sourced out from this pin and an external resistor (RISET) set the voltage at this pin (VISET). The RISET is recommended to be 10k. A noise decoupling capacitor less than 100pF can be added in parallel with the 10k RISET. In the single IC configuration (both 2-phase mode and dual-output mode), this pin can be tied to the ISHARE pin. 3 ISHARE This pin is used for current sharing purposes and is configured to the current share bus representing all modules average current. When in 2-phase mode (VSEN2- pulled within 400mV of VCC), this pin sources a current which is a combination of 15A constant offset current and the average of both sensed channel currents. When in Dual-output mode, this pin sources a current, which is a combination of 15A constant offset current and Channel 1s sensed current. The share bus (ISHARE pins connected together) voltage (VISHARE) set by an external resistor (RISHARE) represents the average current level of all ISL8126 controller connected to the current share bus. The share bus impedance RISHARE should be set as RISET/NCTRL (RISET divided by number of ISL8126 in current sharing controllers). There is a 1.2V threshold for average overcurrent protection on this pin. VISHARE is compared with a 1.2V threshold for average overcurrent protections. When the fault condition on Channel 1 is detected or EN/VFF1 is pulled below its POR, ISHARE is internally pulled to VCC. FN7892.1 2 August 16, 2012 COMP2 FB1 FB2 VMON1 VMON2 VSEN1- VSEN2- VSEN1+ VSEN2+ ISEN1B ISEN2B ISEN1A ISEN2A VCC VIN BOOT1