ISL8120 ® Data Sheet April 7, 2009 Dual/n-Phase Buck PWM Controller with Integrated Drivers 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 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. FN6641.1 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, rDS(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) 1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc. Copyright Intersil Americas Inc. 2008, 2009. All Rights Reserved All other trademarks mentioned are the property of their respective owners. ISL8120 Applications Pinout ISL8120 (32 LD QFN) TOP VIEW • Power Supply for Datacom/Telecom and POL FB1 VMON1 VSEN1- VSEN1+ ISEN1B ISEN1A VCC BOOT1 • Paralleling Power Module 32 31 30 29 28 27 26 25 • Wide and Narrow Input Voltage Range Buck Regulators • DDR I and II Applications • High Current Density Power Supplies • Multiple Outputs VRM and VRD Related Literature • Technical Brief TB389 “PCB Land Pattern Design and Surface Mount Guidelines for QFN (MLFP) Packages” Ordering Information ISET 2 23 PHASE1 ISHARE 3 22 LGATE1 EN/VFF1 4 ISL8120 IRZ -40 to +85 32 Ld QFN L32.5x5B ISL8120IRZ-T* ISL8120 IRZ -40 to +85 32 Ld QFN L32.5x5B * Please refer to TB347 for details on reel specifications. 17 BOOT2 9 10 11 12 13 14 15 16 VIN ISL8120IRZ PGOOD 8 ISEN2A L32.5x5B 18 UGATE2 ISEN2B L32.5x5B 32 Ld QFN CLKOUT/REFIN 7 VSEN2+ 32 Ld QFN 0 to +70 19 PHASE2 VSEN2- 0 to +70 EN/VFF2 6 VMON2 ISL8120 CRZ ISL8120CRZ-T* ISL8120 CRZ 20 LGATE2 FB2 PACKAGE (Pb-free) 21 PVCC 33 GND COMP2 PKG. DWG. # TEMP. RANGE (°C) ISL8120CRZ 24 UGATE1 FSYNC 5 PART MARKING PART NUMBER (Note) COMP1 1 NOTE: These Intersil Pb-free plastic packaged products employ special Pb-free material sets; molding compounds/die attach materials and 100% matte tin plate PLUS ANNEAL - e3 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations. Intersil Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020. 2 March 20, 2009 FN6641.0 Block Diagram EN/FF1 VCC PVCC VIN INTERNAL LINEAR REGULATOR POWER-ON RESET (POR) 5.4V OTP 3 OVER-TEMPERATURE PROTECTION (OTP) CHANNEL 1 REFERENCE VREF = 0.6V BOOT1 SOFT-START AND FAULT LOGIC UGATE1 VCC VREF 700mV SAW1 AVG_OCP PHASE1 FB1 GATE CONTROL ∑ E/A1 PWM1 7-CYCLE DELAY COMP1 ISL8120 + - PVCC OV/UV COMP1 CURRENT CORRECTION CHANNEL1 OCP AVERAGE OCP 1.2V VSEN1+ UNITY GAIN DIFF AMP1 PGOOD COMP1 PGOOD IAVG_CS CHANNEL 1 M/D Control CURRENT CORRECTION LGATE1 ICS1 ISHARE 108µA VSEN1- ICSH_ERR ISEN1A CURRENT SAMPLING ISEN1B ICSH_ERR (BOTTOM PAD) GND VMON1 PGOOD FIGURE 1. CHANNEL/PHASE 1 (VDDQ) April 7, 2009 Block Diagram (Continued) EN/FF2 ISHARE CLKOUT/REFIN FSYNC ICSH_ERR RELATIVE PHASE CONTROL IAVG_CS+15µA CURRENT SHARE BLOCK SAW1 IAVG_CS+15µA ISET IAVG_CS OTP POR 4 k*VDDQ VREF CHANNEL 2 VCC + ICS1 MASTER CLOCK OSCILLATOR GENERATOR ICS2 AVERAGE M/D CONTROL CURRENT + IAVG SOFT-START AND FAULT LOGIC BOOT2 PVCC VREF2 700mV E/A2 7-CYCLE DELAY COMP2 + PWM2 ∑ - CURRENT VREF OV/UV COMP2 PHASE2 GATE CONTROL ISL8120 AVG_OCP FB2 UGATE2 SAW2 M/D CONTROL CORRECTION PVCC - LGATE2 + CHANNEL2 OCP ICS2 GND CHANNEL 2 108µA VSEN2+ ISEN2A CURRENT SAMPLING ISEN2B VSEN2PGOOD COMP2 UNITY GAIN DIFF AMP2 PGOOD M/D = 1: multiphase VMON2 M/D = 0: DUAL OUTPUT OPERATION IAVG_CS = IAVG or ICS1 IAVG = (ICS1 + ICS2) / 2 ICSH_ERR = (VISARE - VISET)/GCS April 7, 2009 0.6V = k*VDDQ FIGURE 2. CHANNEL/PHASE 2 (VTT) ISL8120 Typical Application I (Dual Regulators with DCR Sensing and Remote Sense) VIN VIN_F +3.3 TO +22V RCC CF2 LIN CHFIN CBIN CF1 VCC PVCC BOOT1 CBOOT1 UGATE1 VIN Q1 LOUT1 PHASE1 CF3 VOUT1 COUT1 LGATE1 2kΩ Q2 ISEN1A COMP1 ISL8120 10Ω RISEN1 ISEN1B 10Ω ZCOMP1 FB1 CLKOUT/REFIN ZFB1 VCC VMON1 VSENSE1+ RFB1 VSEN1+ ROS1 VSEN1- PGOOD CSEN1 VSENSE1- VIN_F BOOT2 CBOOT2 RFS UGATE2 FSYNC Q3 LOUT2 PHASE2 VOUT2 Q4 LGATE2 COUT2 2kΩ ISEN2A 10Ω ISEN2B COMP2 EN2/FF2 RISEN2 10Ω ZCOMP2 FB2 EN1/FF1 ZFB2 RSET VMON2 ISET RFB2 VSEN2+ ISHARE VSEN2- ROS2 CSEN2 VSENSE2+ VSENSE2- GND 5 March 20, 2009 FN6641.0 ISL8120 Typical Application II (Double Data Rate I or II) VIN VIN_F +3.3 TO +22V RCC CF2 LIN CHFIN CBIN CF1 VCC PVCC BOOT1 CBOOT1 UGATE1 VIN 2.5V 1.8V LOUT1 PHASE1 CF3 RFS Q1 (DDR I) (DDR II) VDDQ COUT1 LGATE1 FSYNC 2kΩ Q2 ISEN1A COMP1 ISL8120 10Ω RISEN1 ISEN1B 10Ω ZCOMP1 FB1 ZFB1 VMON1 VSENSE1+ RFB1 VSEN1+ VDDQ ROS1 VSEN1- CSEN1 VSENSE1- R*(VTT/0.6-1) (See notes below) CLKOUT/REFIN R 1nF VDDQ Or VIN_F BOOT2 CBOOT2 UGATE2 (Or tie REFIN pin to VMON1 pin) Q3 1.25V (DDR I) 0.9V (DDR II) LOUT2 PHASE2 VTT LGATE2 COUT2 Q4 ( VDDQ/2) 2kΩ ISEN2A 10Ω ISEN2B COMP2 RISEN2 10Ω ZCOMP1 FB2 PGOOD ZFB1 VMON2 RSET ISET RFB2 VSEN2+ ISHARE ROS2 GND VSEN2- CSEN2 VSENSE2+ VSENSE2- Note 1: Set the upper resistor to be a little higher than R*(VDDQ/0.6 - 1) will set the final REFIN voltage (stead state voltage after soft-start) derived from the VDDQ to be a little higher than internal 0.6V reference. In this way, the VTT final voltage will use the internal 0.6V reference after soft-start. The other way is to add more delay at EN/FF1 pin to have Channel 2 tracking VDDQ (check the DDR section for more details). Note 2: Another way to set REFIN voltage is to connect VMON1 directly to REFIN pin. 6 March 20, 2009 FN6641.0 ISL8120 Typical Application III (2-Phase Operation with rDS(ON) Sensing and Voltage Trimming) VIN +3V TO +22V LIN CHFIN CF1 RCC VCC CBIN CF2 PVCC BOOT1 CBOOT1 UGATE1 VIN Q1 LOUT1 VOUT1 PHASE1 CF3 EN/FF1, 2 COUT1 Q2 LGATE1 ISEN1A 10Ω RISEN1 ISEN1B ISL8120 COMP1/2 10Ω VSENSE1+ VSENSE1- ZCOMP1 FB1 RSET ISET DNP VMON1/2 ISHARE RFB1 VSEN1+ ROS1 VSEN1- 0Ω CSEN1 PULLED TO VSENSE1TRIM UP TRIM DOWN PGOOD PULLED TO VSENSE1+ VIN_F BOOT2 CBOOT2 RFS UGATE2 FSYNC Q3 LOUT2 PHASE2 Q4 LGATE2 ISEN2A CLKOUT/REFIN RISEN2 ISEN2B VCC GND FB2 VSEN2- VSEN2+ GND 7 March 20, 2009 FN6641.0 ISL8120 Typical Application IV (3-Phase Regulator with Precision Resistor Sensing) VIN LIN +3V TO +22V CIN CF2 RCC VCC VIN_F PVCC CF1 BOOT1 CBOOT2 VIN CF3 UGATE1 LOUT2 VOUT PHASE1 ISL8120 EN/FF1 Q1 LGATE1 PHASE 2 COUT Q2 ISEN1A CLKOUT/REFIN PGOOD RISEN2 ISEN1B 10Ω COMP1 FB1 BOOT2 10Ω VMON1 UGATE2 PHASE2 VSEN1+ LGATE2 VSEN1- ISEN2A VSENSE1+ VCC VSENSE1- GND ISEN2B EN/FF2 GND FSYNC FB2 VMON2 ISHARE VSEN2+ ISET R RCC VCC CF1 VIN FSYNC EN/FF1, 2 BOOT2 Q1 CBOOT1 LOUT1 PHASE1 EN/FF1,2 PGOOD LGATE1 Q2 ISL8120 PHASE 1 AND 3 ISEN1A RISEN1 ISEN1B CBOOT3 Q3 VIN_F UGATE1 RFS LOUT3 CF2 PVCC BOOT1 CF3 VIN_F R VSEN2- VCC UGATE2 COMP1/2 PHASE2 ZCOMP1 FB1 Q4 ZFB1 VMON1/2 LGATE2 RFB1 VSEN1+ ISEN2A VSEN1- ROS1 CSEN1 ISEN2B RISEN3 VCC GND VCC ISHARE FB2 VSEN2+ R VSEN2- CLKOUT/REFIN GND ISET R 8 March 20, 2009 FN6641.0 ISL8120 Typical Application V (4 Phase Operation with DCR Sensing) VIN LIN +3V TO +22V VIN_F CIN VCC RCC CF2 PVCC CF1 BOOT1 CBOOT2 VIN CF3 UGATE1 CLKOUT/REFIN Q1 LGATE1 EN/FF1, 2 VCC VCC VCC FB2 ISL8120 ISEN1A PHASE 2 AND 4 ISEN1B VSEN1,2- 10Ω RISEN2 COMP1/2 VIN_F BOOT2 Q3 Q4 10Ω FB1 CBOOT4 LOUT4 VOUT1 COUT Q2 PGOOD VSEN1, 2+ LOUT2 PHASE1 UGATE2 VMON1/2 PHASE2 ISET ISEN2A COS ROS1 R GND LGATE2 RFB1 2ND DIVIDER TO AVOID SINGLE POINT FAILURE VSENSE1+ VSENSE1- FSYNC ISEN2B ISHARE RISEN4 R VCC RCC CF1 CF2 PVCC VIN_F BOOT1 VIN FSYNC CF3 UGATE1 Q1 CBOOT1 LOUT1 PHASE1 RFS LGATE1 EN/FF1, 2 Q2 PGOOD VIN_F BOOT2 CBOOT3 LOUT3 ISL8120 ISEN1A PHASE 1 AND 3 ISEN1B UGATE2 Q3 COMP1/2 PHASE2 RISEN1 ZCOMP1 ZFB1 FB1 VMON1/2 Q4 LGATE2 RFB1 VSEN1+ ISEN2A RISEN3 VSEN1- ROS1 CSEN1 ISEN2B ISHARE FB2 VCC VSEN2+ VCC R VSEN2- VCC CLKOUT/REFIN GND ISET R 9 March 20, 2009 FN6641.0 ISL8120 Typical Application VI (3-Phase Regulator with Resistor Sensing and 1 Phase Regulator) VIN LIN +3V to +22V VCC RCC VIN_F CIN CF2 PVCC CF1 BOOT1 CBOOT2 VIN CF3 UGATE1 PHASE 2 LOUT2 VOUT1 PHASE1 EN/FF2 LGATE1 EN/FF1 PGOOD VCC Q1 COUT1 Q2 ISEN1A CLKOUT/REFIN VIN_F RISEN2 ISEN1B COMP1 BOOT2 10Ω CBOOT4 LOUT4 VOUT2 Q3 UGATE2 FB1 PHASE2 VMON1 COUT2 ISL8120 10Ω VSEN1+ LGATE2 Q4 VSEN1ISEN2A VSENSE1+ VCC ISET 10Ω VSENSE1- ISEN2B R 10Ω ZFB2 RISEN4 ZCOMP2 FSYNC FB2 ISHARE VMON2 VSEN2+ VSENSE2+ VSEN2- GND R PHASE 2 VSENSE2- VCC RCC CF1 BOOT1 VIN FSYNC CF3 UGATE1 LGATE1 PGOOD EN/FF1, 2 BOOT2 ISL8120 Q3 Q2 ISEN1A RISEN1 ISEN1B CBOOT3 LOUT3 CBOOT1 LOUT1 Q1 PHASE1 RFS VIN_F CF2 VIN_F PVCC UGATE2 COMP1/2 PHASE2 ZCOMP1 FB1 Q4 ZFB1 VMON1/2 LGATE2 RFB1 VSEN1+ ISEN2A VSEN1- ROS1 CSEN1 ISEN2B VCC RISEN3 GND VCC ISHARE FB2 VSEN2+ PHASE 1 AND 3 R ISET VSEN2+ 10 CLKOUT/REFIN VSEN2GND R March 20, 2009 FN6641.0 ISL8120 Typical Application VIII (Multiple Power Modules in Parallel with Current Sharing Control) VIN +3V to +22V LIN CIN VCC RCC2 CF4 CF5 PVCC BOOT1 CBOOT3 VIN CF6 UGATE1 PGOOD PHASE1 CLKOUT/REFIN LGATE1 Q5 LOUT3 COUT2 Q6 2kΩ EN/FF1, 2 ISEN1A VIN BOOT2 ISEN1B CBOOT4 LOUT4 VOUT2 PHASE2 10Ω COMP1/2 ISL8120 Q8 LGATE2 ZCOMP2 ZFB2 FB1 VMON1/2 2kΩ RFB2 VSEN1+ ISEN2A RISEN4 GND VCC 2-PHASE MODULE #1 ROS2 RCSR2 VSEN1- ISEN2B VSEN2+ FB2 10Ω RISEN3 UGATE2 Q7 CSEN2 VSENSE2+ VSENSE2VLOAD FSYNC ISHARE VSEN2- GND ISET R R VCC RCC1 CF1 CF2 PVCC VIN_F BOOT1 VIN FSYNC CF3 UGATE1 Q1 CBOOT1 LOUT1 VOUT1 PHASE1 RFS LGATE1 EN/FF1, 2 COUT1 Q2 2kΩ PGOOD ISEN1A VIN BOOT2 RISEN1 ISEN1B CBOOT2 LOUT2 UGATE2 Q3 COMP1/2 PHASE2 ZFB1 FB1 ISL8120 Q4 10Ω ZCOMP1 LGATE2 ISEN2A RISEN2 RFB1 VSEN1+ 2kΩ 10Ω VMON1/2 VSEN1- RCSR1 ROS1 CSEN1 VSENSE1+ VSENSE1- ISEN2B ISHARE VSEN2+ GND VCC FB2 2-PHASE MODULE #2 R CLKOUT/REFIN VSEN2GND ISET R 11 March 20, 2009 FN6641.0 ISL8120 Typical Application VII (6 Phase Operation with DCR Sensing) +3V TO +22V VIN LIN RCC VCC CF1 VIN CLKOUT/REFIN CF3 EN/FF1, 2 PVCC BOOT1 VIN_F CIN CF2 UGATE1 PHASE1 Q1 LGATE1 Q2 CBOOT3 LOUT3 PGOOD GND VCC VIN_F CBOOT6 LOUT6 FB2 VSEN2+ VSEN2BOOT2 Q3 Q4 ISL8120 PHASE 3 AND 6 UGATE2 PHASE2 LGATE2 ISEN1A ISEN1B COMP1/2 FB1 VMON1/2 VSEN1+ VSEN1ISET RISEN3 VCC R ISEN2A FSYNC ISEN2B ISHARE GND RISEN6 R VCC CF1 RCC VIN CF3 EN/FF1,2 PGOOD VIN_F CBOOT5 LOUT5 Q4 RISEN5 GND VCC VIN_F CF2 UGATE1 PHASE1 Q1 LGATE1 Q2 UGATE2 PHASE2 ISL8120 LGATE2 RISEN2 COMP1/2 FB1 VMON1/2 VSEN1+ VSEN1- ISEN2A VCC CLKOUT/REFIN ISEN2B FSYNC FB2 VSEN2+ VSEN2- CBOOT2 LOUT2 ISEN1A ISEN1B BOOT2 Q3 PVCC BOOT1 PHASE 2 AND 5 GND ISHARE ISET R R VIN_F VCC CF1 CF3 FSYNC RCC VIN EN/FF1, 2 PGOOD VIN_F CBOOT4 LOUT4 UGATE2 PHASE2 ISL8120 Q4 LGATE2 RISEN4 GND VCC FB2 VSEN2+ VSEN2- LGATE1 Q2 PHASE 1 AND 4 CBOOT1 LOUT1 VOUT1 COUT1 RISEN1 10Ω ZFB1 10Ω ZCOMP1 VMON2 ROS1 VSEN1ISHARE GND 12 Q1 VSEN1+ ISEN2A ISEN2B CF2 UGATE1 PHASE1 ISEN1A ISEN1B VMON1 FB1 COMP1/2 BOOT2 Q3 PVCC BOOT1 CLKOUT/REFIN ISET RFB1 ROS1 RFB1 CSEN1 VSENSE1+ VSENSE1- R R March 20, 2009 FN6641.0 ISL8120 Typical Application VIIII (4 Outputs Operation with DCR Sensing) VIN LIN +3V TO +22V CF3 VSENSE4+ EN/FF2 VSEN2+ RFB4 VSENSE4ZFB3 2Ω PVCC BOOT1 VIN CLKOUT/REFIN CSEN4 ROS4 2Ω RCC VCC CF1 VIN_F COUT4 CBOOT6 LOUT6 VOUT4 VSEN2VMON2 FB2 ZCOMP4 COMP2 PGOOD BOOT2 Q4 Q1 LGATE1 Q2 CBOOT3 LOUT3 VOUT3 COUT3 (PHASE 3 and 6) 2Ω RISEN3 2Ω ZFB3 RFB3 VSEN1+ ROS3 VSEN1ISHARE/ISET EN/FF1 R FSYNC VSENSE3+ CSEN3 VSENSE3- ISEN2A OUTPUT 3 AND 4 GND ISEN2B RCC VCC CF1 PVCC BOOT1 VIN CF3 EN/FF1, 2 PGOOD VIN_F LOUT5 UGATE1 PHASE1 COMP1 FB1 VMON1 ISL8120 LGATE2 RISEN6 CBOOT2 CF2 ISEN1A ISEN1B UGATE2 PHASE2 Q3 VIN_F CIN Q4 UGATE2 PHASE2 ISL8120 LGATE2 (PHASE 2 and 5) VCC LGATE1 Q2 CBOOT1 LOUT2 VOUT2 COUT2 RISEN2 2Ω 2Ω RFB2 CSEN2 ROS2 VSEN1CLKOUT/REFIN FSYNC ISEN2B GND Q1 COMP1/2 ZCOMP2 FB1 ZFB2 VMON1/2 VSEN1+ ISEN2A RISEN5 UGATE1 PHASE1 ISEN1A ISEN1B BOOT2 Q3 VIN_F CF2 VSENSE2+ VSENSE2- ISHARE/ISET FB2 VSEN2+ VSEN2- OUTPUT 2 GND R VIN_F VCC CF1 FSYNC CF3 RCC VIN EN/FF1, 2 PGOOD VIN_F CBOOT4 LOUT4 BOOT2 Q3 Q4 UGATE2 PHASE2 LGATE2 ISL8120 (PHASE 1 and 4) GND VCC 13 FB2 VSEN2+ VSEN2- OUTPUT 1 CF2 UGATE1 PHASE1 Q1 LGATE1 Q2 ISEN1A ISEN1B VMON1 FB1 COMP1/2 CBOOT1 LOUT1 VOUT1 COUT1 RISEN1 2Ω ZFB1 2Ω ZCOMP1 VMON2 VSEN1+ ISEN2A ISEN2B RISEN4 PVCC BOOT1 ROS1 VSEN1ISHARE/ISET CLKOUT/REFIN RFB1 ROS1 RFB1 CSEN1 VSENSE1+ VSENSE1- R GND March 20, 2009 FN6641.0 ISL8120 Absolute Maximum Ratings Thermal Information Input Voltage, VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to +27V Driver Bias Voltage, PVCC . . . . . . . . . . . . . . . . . . . . -0.3V to +6.5V Signal Bias Voltage, VCC . . . . . . . . . . . . . . . . . . . . . -0.3V to +6.5V BOOT/UGATE Voltage, VBOOT . . . . . . . . . . . . . . . . . . -0.3V to +36V Phase Voltage, VPHASE . . . . . . . . . . VBOOT - 7V to VBOOT + 0.3V BOOT to PHASE Voltage, VBOOT - VPHASE . . -0.3V to VCC +0.3V Input, Output or I/O Voltage . . . . . . . . . . . . . . . . -0.3V to VCC +0.3V Thermal Resistance (Typical Notes 1, 2) θJA(°C/W) θJC(°C/W) 32 Ld QFN Package . . . . . . . . . . . . . . 32 3.5 Maximum Junction Temperature . . . . . . . . . . . . . . .-55°C to +150°C Maximum Storage Temperature Range . . . . . . . . . .-65°C to +150°C Pb-Free Reflow Profile. . . . . . . . . . . . . . . . . . . . . . . . .see link below http://www.intersil.com/pbfree/Pb-FreeReflow.asp Recommended Operating Conditions Input Voltage, VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3V to 22V Driver Bias Voltage, PVCC . . . . . . . . . . . . . . . . . . . . . . . 3V to 5.6V Signal Bias Voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . 3V to 5.6V Boot to Phase Voltage (Overcharged), VBOOT - VPHASE . . . . . .<6V Commercial Ambient Temperature Range. . . . . . . . . . 0°C to +70°C Industrial Ambient Temperature Range . . . . . . . . . . .-40°C to +85°C Maximum Junction Temperature Range . . . . . . . . . . . . . . . . +125°C CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact product reliability and result in failures not covered by warranty. NOTES: 1. θJA is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach” features. 2. For θJC, the “case temp” location is the center of the exposed metal pad on the package underside. Electrical Specifications Recommended Operating Conditions, Unless Otherwise Noted. PARAMETER SYMBOL TEST CONDITIONS MIN (Note 4) TYP MAX (Note 4) UNITS VCC SUPPLY CURRENT Nominal Supply VIN Current IQ_VIN VIN = 20V; VCC = PVCC; No Load; FSW = 500kHz 11 15 20 mA Nominal Supply VIN Current IQ_VIN VIN = 3.3V;VCC = PVCC; No Load; FSW = 500kHz 8 12 14 mA Shutdown Supply PVCC Current IPVCC EN = 0V, PVCC = 5V 0.5 1 1.4 mA 7 10 12 mA Shutdown Supply VCC Current IVCC EN = 0V, VCC = 3V IPVCC PVCC = 4V TO 5.6V 250 mA PVCC = 3V TO 4V 150 mA 1 Ω INTERNAL LINEAR REGULATOR Maximum Current (Note 3) Saturated Equivalent Impedance (Note 3) RLDO P-Channel MOSFET (VIN = 5V) PVCC Voltage Level PVCC IPVCC = 0mA to 250mA 5.1 5.4 5.6 V Rising VCC Threshold 2.85 2.97 V Falling VCC Threshold 2.65 2.75 V ISL8120CRZ 2.85 2.97 V ISL8120IRZ 2.85 3.05 2.65 2.75 POWER-ON RESET Rising PVCC Threshold Falling PVCC Threshold System Soft-start Delay (Note 3) tSS_DLY After PLL, VCC, and PVCC PORs, and EN(s) above their thresholds 384 V Cycles ENABLE Turn-On Threshold Voltage Hysteresis Sink Current IEN_HYS 14 0.75 0.8 0.86 V 25 30 35 µA March 20, 2009 FN6641.0 ISL8120 Electrical Specifications Recommended Operating Conditions, Unless Otherwise Noted. (Continued) PARAMETER SYMBOL Undervoltage Lockout Hysteresis (Note 3) VEN_HYS TEST CONDITIONS MIN (Note 4) VEN_RTH = 10.6V; VEN_FTH = 9V IEN_SINK Sink Impedance REN_SINK MAX (Note 4) 1.5 RUP = 53.6kΩ, RDOWN = 5.23kΩ Sink Current TYP IEN_SINK = 5mA UNITS V 15 mA 65 Ω 1500 kHz 406 kHz +9 % OSCILLATOR Oscillator Frequency Range 150 Oscillator Frequency RFS = 100k, Figure 21 Total Variation VCC = 5V; -40°C < TA <+85°C 344 377 -9 Peak-to-Peak Ramp Amplitude ΔVRAMP VCC = 5V, VEN = 0.8V 1 Linear Gain of Ramp Over VEN GRAMP GRAMP = ΔVRAMP/VEN 1.25 Ramp Peak Voltage VRAMP_PEAK VEN = VCC Peak-to-Peak Ramp Amplitude ΔVRAMP VEN = VCC = 5.4V, RUP = 2k Peak-to-Peak Ramp Amplitude ΔVRAMP VEN = VCC = 3V; RUP = 2k Ramp Amplitude Upon Disable ΔVRAMP VEN = 0V; VCC = 3.5V to 5.5V Ramp Amplitude Upon Disable ΔVRAMP VEN = 0V; VCC < 3.4V Ramp DC Offset VRAMP_OS VP-P VCC - 1.4 V 3 VP-P 0.6 VP-P 1 VP-P VCC - 2.4 VP-P 1 V FREQUENCY SYNCHRONIZATION AND PHASE LOCK LOOP Synchronization Frequency VCC = 5.4V (2.97V) PLL Locking Time VCC = 5.4V (2.97V); FSW = 400kHz; Input Signal Duty Cycle Range (Note 3) 150 1500 105 10 kHz µs 90 % 410 ns PWM Minimum PWM OFF Time tMIN_OFF Current Sampling Blanking Time (Note 3) 310 tBLANKING 345 175 ns 0.6 V REFERENCE Channel 1 Reference Voltage (Include Error and Differential Amplifiers’ Offsets) VREF1 ISL8120CRZ -0.6 ISL8120IRZ 0.6 0.6 -0.7 Channel 2 Reference Voltage (Include Error and Differential Amplifiers’ Offsets) VREF2 % ISL8120CRZ V 0.7 % 0.6 -0.75 ISL8120IRZ V 0.75 0.6 -0.75 % V 0.95 % ERROR AMPLIFIER DC Gain (Note 3) Unity Gain-Bandwidth (Note 3) UGBW_EA RL = 10k, CL = 100pF, at COMP Pin 98 dB RL = 10k, CL = 100pF, at COMP Pin 80 MHz Input Common Mode Range (Note 3) Output Voltage Swing VCC = 5V Slew Rate (Note 3) SR_EA Input Current (Note 3) IFB 15 -0.2 VCC - 1.8 V 0.85 VCC - 1.0 V RL = 10k, CL = 100pF, at COMP Pin 20 V/µs Positive Direction Into the FB pin 100 nA March 20, 2009 FN6641.0 ISL8120 Electrical Specifications Recommended Operating Conditions, Unless Otherwise Noted. (Continued) PARAMETER SYMBOL TEST CONDITIONS MIN (Note 4) TYP MAX (Note 4) UNITS Output Sink Current ICOMP 3 mA Output Source Current ICOMP 6 mA Disable Threshold (Note 3) VVSEN- VCC - 0.4 V 0 dB UGBW_DA 5 MHz Negative Input Source Current (Note 3) IVSEN- 100 nA Maximum Source Current for Current Sharing (Typical Application VIII) (Note 3) IVSEN1- 350 µA 1 MΩ DIFFERENTIAL AMPLIFIER DC Gain (Note 3) UG_DA Unity Gain Bandwidth (Note 3) Unity Gain Amplifier VSEN1- Source Current for Current Sharing when parallel multiple modules each of which has its own voltage loop RVSEN+_to _VSEN- Input Impedance Output Voltage Swing (Note 3) Input Common Mode Range (Note 3) Disable Threshold (Note 3) 0 VCC - 1.8 V -0.2 VCC - 1.8 V VVSEN- VMON1, 2 = Tri-State VCC - 0.4 V Upper Drive Source Resistance RUGATE 45mA Source Current 1.0 Ω Upper Drive Sink Resistance RUGATE 45mA Sink Current 1.0 Ω Lower Drive Source Resistance RLGATE 45mA Source Current 1.0 Ω Lower Drive Sink Resistance RLGATE 45mA Sink Current 0.4 Ω Channel Overcurrent Limit (Note 3) ISOURCE VCC = 2.97V to 5.6V 108 µA Channel Overcurrent Limit ISOURCE VCC = 5V; ISL8120CRZ 94 108 122 µA VCC = 5V; ISL8120IRZ 89 108 122 µA 1.16 1.20 1.22 V GATE DRIVERS OVERCURRENT PROTECTION Share Pin OC Threshold VOC_SET Share Pin OC Hysteresis (Note 3) VCC = 2.97V to 5.6V (comparator offset included) VOC_SET_HYS VCC = 2.97V to 5.6V (comparator offset included) 50 mV CURRENT SHARE Internal Balance Accuracy (Note 3) VCC = 2.97V and 3.6V, 1% Resistor Sense, 10mV Signal ±5 % Internal Balance Accuracy (Note 3) VCC = 4.5V and 5.6V, 1% Resistor Sense, 10mV Signal ±5 % External Current Share Accuracy (Note 3) VCC = 2.97V and 5.6V, 1% Resistor Sense, 10mV Signal ±5 % POWER GOOD MONITOR Undervoltage Falling Trip Point VUVF Undervoltage Rising Hysteresis VUVR_HYS Overvoltage Rising Trip Point VOVR Overvoltage Falling Hysteresis VOVF_HYS Percentage Below Reference Point -15 Percentage Above UV Trip Point Percentage Above Reference Point Percentage below OV Trip Point -13 -11 % 4 11 13 % 15 % 4 % PGOOD Low Output Voltage IPGOOD = 2mA 0.35 V Sinking Impedance IPGOOD = 2mA 70 Ω 16 March 20, 2009 FN6641.0 ISL8120 Electrical Specifications Recommended Operating Conditions, Unless Otherwise Noted. (Continued) PARAMETER SYMBOL Maximum Sinking Current (Note 3) TEST CONDITIONS MIN (Note 4) VPGOOD <0.8V TYP MAX (Note 4) 10 UNITS mA OVERVOLTAGE PROTECTION OV Latching Up Trip Point EN/FF= UGATE = LATCH Low, LGATE = High 118 120 122 % OV Non-Latching Up Trip Point (Note 3) EN/FF = Low, UGATE = Low, LGATE = High 113 % LGATE Release Trip Point EN/FF = Low/HIGH, UGATE = Low, LGATE = Low 87 % Over-Temperature Trip (Note 3) 150 °C Over-Temperature Release Threshold (Note 3) 125 °C OVER-TEMPERATURE PROTECTION NOTES: 3. Limits should be considered typical and are not production tested 4. Parameters with MIN and/or MAX limits are 100% tested at +25°C, unless otherwise specified. Temperature limits established by characterization and are not production tested. 17 March 20, 2009 FN6641.0 ISL8120 Functional Pin Descriptions GND (Pin 33) The bottom pad is the signal and power ground plane. All voltage levels are referenced to this pad. This pad provides a return path for the low-side MOSFET drives and internal power circuitries as well as all analog signals. Connect this pad to the circuit ground with the shortest possible path (more than 5 to 6 vias to the internal ground plane, placed on the soldering pad are recommended). VIN (Pin 16) This pin is the input of the internal linear regulator. It should be tied directly to the input rail. When used with an external 5V supply, this pin should be tied directly to PVCC. The internal linear device is protected against reverse bias generated by the remaining charge of the decoupling capacitor at PVCC when losing the input rail. VCC (Pin 26) This pin provides bias power for the analog circuitry. An RC filter is recommended between the connection of this pin to a 3V to 5.6V bias (typically PVCC). R is suggested to be a 5Ω resistor. And in 3.3V applications, the R could be shorted to allow the low end input in concerns of the VCC falling threshold. The VCC decoupling capacitor C is strongly recommended to be as large as a 10µF ceramic capacitor. This pin can be powered either by the internal linear regulator or by an external voltage source. BOOT1, 2 (Pins 25, 17) This pin provides the bootstrap bias for the high-side driver. Internal bootstrap diodes connected to the PVCC pin provide the necessary bootstrap charge. Its typical operational voltage range is 2.5V to 5.6V. UGATE1, UGATE2 (Pin 24, 18) These pins provide the drive for the high-side devices and should be connected to the MOSFETs’ gates. PHASE1, PHASE2 (Pins 23,19) Connect these pins to the source of the high-side MOSFETs and the drain of the low-side MOSFETs. These pins represent the return path for the high-side gate drives. PVCC (Pin 21) This pin is the output of the internal series linear regulator. It provides the bias for both low-side and high-side drives. Its operational voltage range is 3V to 5.6V. The decoupling ceramic capacitor in the PVCC pin is 10µF. will lock to an external frequency source if this pin is connected to a switching square pulse waveform, typically the CLKOUT input signal from another ISL8120 or an external clock. The internal oscillator synchronizes with the leading edge of the input signal. EN/FF1, EN/FF2 (Pins 4, 6) These pins have triple functions. The voltage on EN/FF_ pin is compared with a precision 0.8V threshold for system enable to initiate soft-start. With a voltage lower than the threshold, the corresponding channel can be disabled independently. By connecting these pins to the input rail through a voltage resistor divider, the input voltage can be monitored for UVLO (undervoltage lockout ) function. The undervoltage lockout and its hysteresis levels can be programmed by these resistor dividers. The voltages on these pins are also fed into the controller to adjust the sawtooth amplitude of each channel independently to realize the feed-forward function. Furthermore, during fault (such as overvoltage, overcurrent, and over-temperature) conditions, these pins (EN/FF_) are pulled low to communicate the information to other cascaded ICs. PGOOD (Pin 8) Provides an open drain Power-Good signal when both channels are within 9% of the nominal output regulation point with 4% hysteresis (13%/9%) and soft-start complete. PGOOD monitors the outputs (VMON1/2) of the internal differential amplifiers. ISEN1A, ISEN2A (Pins 27, 15) These pins are the non-inverting (+) inputs of the current sensing amplifiers to provide rDS(ON), DCR, or precision resistor current sensing together with the ISEN1B, ISEN2B pins. ISEN1B, ISEN2B (Pins 28, 14) These pins are the inverting (-) inputs of the current sensing amplifiers to provide rDS(ON), DCR, or precision resistor current sensing together with the ISEN1A, ISEN2A pins. Refer to “Typical Application III (2-Phase Operation with rDS(ON) Sensing and Voltage Trimming)” on page 7 for rDS(ON) sensing set up and “Typical Application V (4 Phase Operation with DCR Sensing)” on page 9 for DCR sensing set up. ISET (Pin 2) These pins provide the drive for the low-side devices and should be connected to the MOSFETs’ gates. This pin sources a 15µA offset current plus the average current of both channels in multiphase mode or only Channel 1’s current in independent mode. The voltage (VISET) set by an external resistor (RISET) represents the average current level of the local active channel(s). FSYNC (Pin 5) ISHARE (Pin 3) The oscillator switching frequency is adjusted by placing a resistor (RFS) from this pin to GND. The internal oscillator This pin is used for current sharing purposes and is configured to current share bus representing all modules’ LGATE1, LGATE2 (Pins 22, 20) 18 March 20, 2009 FN6641.0 ISL8120 average current. It sources 15µA offset current plus the average current of both channels in multiphase mode or Channel 1’s current in independent mode. The share bus (ISHARE pins connected together) voltage (VISHARE) set by an external resistor (RISHARE) represents the average current level of all active channel(s). The ISHARE bus voltage compares with each reference voltage set by each RISET and generates current share error signal for current correction block of each cascaded controller. The share bus impedance RISHARE should be set as RISET/NCTRL (RISET divided by number of active 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. For full-scale current, RISHARE should be 1.2V/123µA = ~10kΩ. Typically 10kΩ is used for RSHARE and RSET. CLKOUT/REFIN (Pin 7) This pin has a dual function depending on the mode in which the chip is operating. It provides a clock signal to synchronize with other ISL8120(s) with its VSEN2- pulled within 700mV of VCC for multiphase (3-, 4-, 6-, 8-, 10-, or 12-phase) operation. When the VSEN2- pin is not within 700mV of VCC, ISL8120 is in dual mode (dual independent PWM output). The clockout signal of this pin is not available in this mode, but the ISL8120 can be synchronized to external clock. In dual mode, this pin works as the following two functions: 1. An external reference (0.6V target only) can be in place of the Channel 2’s internal reference through this pin for DDR/tracking applications (see “Internal Reference and System Accuracy” on page 33). 2. The ISL8120 operates as a dual-PWM controller for two independent regulators with selectable phase degree shift, which is programmed by the voltage level on REFIN (see “DDR and Dual Mode Operation” on page 32). FB1, FB2 (Pins 32, 10) These pins are the inverting inputs of the error amplifiers. These pins should be connected to VMON1, 2 with the compensation feedback network. No direct connection between FB and VMON pins is allowed. With VSEN2- pulled within 700mV of VCC, the corresponding error amplifier is disabled and the amplifier’s output is high impedance. FB2 is one of the two pins to determine the relative phase relationship between the internal clock of both channels and the CLKOUT signal. See “DDR and Dual Mode Operation” on page 32. COMP1, COMP2 (Pins 1, 9) 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 700mV of VCC, the corresponding error amplifier is disabled and its output (COMP pin) is high impedance. Thus, in multiphase 19 operations, all other SLAVE phases’ COMP pins can tie to the MASTER phase’s COMP1 pin (1st phase), which modulates each phase’s 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. VSEN1+, VSEN2+ (Pins 29, 13) These pins are the positive inputs of the standard unity gain operational amplifier for differential remote sense for the corresponding channel (Channels 1 and 2), and should be connected to the positive rail of the load/processor. These pins can also provide precision output voltage trimming capability by pulling a resistor from this pin to the positive rail of the load (trimming down) or the return (typical VSEN1-, VSEN2- pins) of the load (trimming up). The typical input impedance of VSEN+ with respect to VSEN- is 500kΩ. By setting the resistor divider connected from the output voltage to the input of the differential amplifier, the desired output voltage can be programmed. To minimize the system accuracy error introduced by the input impedance of the differential amplifier, a resistor below 1k is recommended to be used for the lower leg (ROS) of the feedback resistor divider. With VSEN2- pulled within 700mV of VCC, the corresponding error amplifier is disabled and VSEN2+ is one of the two pins to determine the relative phase relationship between the internal clock of both channels and the CLKOUT signal. See “DDR and Dual Mode Operation” on page 32 for details. VSEN1-, VSEN2- (Pins 30, 12) These pins are the negative inputs of standard unity gain operational amplifier for differential remote sense for the corresponding regulator (Channels 1and 2), and should be connected to the negative rail of the load/processor. When VSEN1-, VSEN2- are pulled within 700mV of VCC, the corresponding error amplifier and differential amplifier are disabled and their outputs are high impedance. Both VSEN2+ and FB2 input signal levels determine the relative phases between the internal controllers as well as the CLKOUT signal. See “DDR and Dual Mode Operation” on page 32 for details. When configured as multiple power modules (each module with independent voltage loop) operating in parallel, in order to implement the current sharing control, a resistor (100Ω typ) needs to be inserted between the VSEN1- pin and the output voltage negative sense point (between VSEN1- and lower voltage sense resistor), as shown in the “Typical Application VIII (Multiple Power Modules in Parallel with Current Sharing Control)” on page 11. This introduces a correction voltage for the modules with lower load current to keep the current distribution balanced among modules. The module with the highest load current will automatically become the master module. The recommended value for the March 20, 2009 FN6641.0 ISL8120 VSEN1- resistor is 100Ω and it should not be large in order to keep the unit gain amplifier input impedance compatibility. VMON1, VMON2 (Pins 31, 11) These pins are outputs of the unity gain amplifiers. They are connected internally to the OV/UV/PGOOD comparators. These pins should be connected to the FB1, FB2 pins by a standard feedback network when both channels are operating independently. When VSEN1-, VSEN2- are pulled within 700mV of VCC, the corresponding differential amplifier is disabled and its output (VMON pin) is high impedance. In such an event, the VMON pin can be used as an additional monitor of the output voltage with a resistor divider to protect the system against single point of failure, which occurs in the system using the same resistor divider for both of the UV/OV comparator and output voltage feedback. Modes of Operation There are 9 typical operation modes depending upon the signal levels on EN1/FF1, EN2/FF2, VSEN2+, VSEN2-, FB2, and CLKOUT/REFIN. MODE 1: The IC is completely disabled when EN1/FF1 and EN2/FF2 are pulled below 0.8V. MODE 2: With EN1/FF1 pulled low and EN2/FF2 pulled high (Mode 2A), or EN1/FF1 pulled high and EN2/FF2 pulled low (Mode 2B), the ISL8120 operates as a single phase regulator. The current sourcing out from the ISHARE pin represents the first channel current plus 15µA offset current. MODE 3: When VSEN2- is used as a negative sense line, both channels’ phase shift depends upon the voltage level of CLKOUT/REFIN. When the CLKOUT/REFIN pin is within 29% to 45% of VCC, Channel 2 delays 0° over Channel 1 (Mode 3A); when within 45% to 62% of VCC, 90°delay (Mode 3B); when greater than 62% to VCC, 180° delay (Mode 3C). Refer to the “DDR and Dual Mode Operation” on page 32. MODE 4: When VSEN2- is used as a negative remote sense line, and CLKOUT/REFIN is connected to an external voltage ramp lower than the internal soft-start ramp and lower than 0.6V, the external ramp signal will replace Channel 2’s internal soft-start ramp to be tracked at start-up, controller operating in DDR mode. The controller will use the lowest voltage among the internal 0.6V reference, the external voltage in CLKOUT/REFIN pin and the soft-start ramp signal. Channel 1 is delayed 60° behind Channel 2. Refer to the “DDR and Dual Mode Operation” on page 32. 20 MODE 5: With VSEN2- pulled within 700mV of VCC and FB2 pulled to ground, the internal channels are 180° out-of-phase and operate in 2-phase single output mode (5A). The CLKOUT/REFIN pin (rising edge) also signals out clock with 60° phase shift relative to the Channel 1’s clock signal (falling edge of PWM) for 6-phase operation with two other ISL8120s (5B). When the share pins are not connected to each other for the three ICs in sync, two of which can operate in Mode 5A (3 independent outputs can be generated (Mode 5D)) and Modes 3 and 4 (to generate 4 independent outputs (Mode 5C)) respectively. MODE 6: With VSEN2- pulled within 700mV of VCC, FB2 pulled high and VSEN2+ pulled low, the internal channels (as 1st and 3rd Phase, respectively) are 240° out-of-phase and operate in 3-phase single output mode, combined with another ISL8120 at MODE 2B. The CLKOUT/REFIN pin signals out 120° relative phases to the falling edge of Channel 1’s clock signal to synchronize with the second ISL8120’s Channel 1 (as 2nd Phase). MODE 7: With VSEN2- pulled within 700mV of VCC and FB2 and VSEN2+ pulled high, the internal channel is 180° out-of-phase. The CLKOUT/REFIN pin (rising edge) signals out 90° relative phase to the Channel 1’s clock signal (falling edge of PWM) to synchronize with another ISL8120, which can operate at Mode 3, 4, 5A, or 7A. A 4-phase single output converter can be constructed with two ISL8120s operating in Mode 5A or 7A (Mode 7A). If the share bus is not connected between ICs, each IC could generate an independent output (Mode 7B). When the second ISL8120 operates as two independent regulators (Mode 3) or in DDR mode (Mode 4), then a three independent output system is generated (Mode 7C). Both ICs can also be constructed as a 3-phase converter (0°, 90°, and 180°, not a equal phase shift for 3-phase) with a single phase regulator (270°). MODE 8: The output CLKOUT signal allows expansion for 12-phase operation with the cascaded sequencing, as shown in Table 1. No external clock is required in this mode for the desired phase shift. MODE 9: With an external clock, the part can be expanded for 5, 7, 8, 9 10 and 11 phase single output operation with the desired phase shift. March 20, 2009 FN6641.0 ISL8120 TABLE 1. 1ST IC (I = INPUT; O = OUTPUT; I/O = INPUT AND OUTPUT, Bi-DIRECTION) EN1/ EN2/ FF1 FF2 VSEN2(I) (I) FB2 (I) (I) MODE - - ISHARE (I/O) REPRESENTS WHICH CHANNEL(S) CURRENT MODES OF OPERATION VSEN2 + (I) CLKOUT/REFIN WRT 1ST (I or O) - - - - - - DISABLED - N/A VMON1 = VMON2 to Keep PGOOD Valid - - SINGLE PHASE - 1ST CHANNEL VMON1 = VMON2 to Keep PGOOD Valid - - SINGLE PHASE 2ND CHANNEL WRT 1ST (O)* OPERATION OPERATION OUTPUT (See MODE MODE Description of 3RD IC of 2ND IC for Details) 1 0 0 2A 0 1 2B 1 0 3A - - <VCC - ACTIVE ACTIVE 29% to 45% of 0.7V VCC (I) 1ST CHANNEL 0° - - DUAL REGULATOR 3B - - <VCC - ACTIVE ACTIVE 45% to 62% of 0.7V VCC (I) 1ST CHANNEL 90° - - DUAL REGULATOR 3C - - <VCC - ACTIVE ACTIVE > 62% of VCC (I) 0.7V 1ST CHANNEL 180° - - DUAL REGULATOR 4 - - <VCC0.7V 1ST CHANNEL -60° - - DDR MODE 5A - - VCC GND - 60° BOTH CHANNELS 180° - - 2-PHASE ACTIVE ACTIVE ACTIVE - - - ACTIVE ACTIVE < 29% of VCC (I) 5B - - VCC GND - 60° BOTH CHANNELS 180° 5A 5A or 7A 6-PHASE 5C - - VCC GND - 60° BOTH CHANNELS 180° 5A 5A or 7A 3 OUTPUTs 5D - - VCC GND - 60° BOTH CHANNELS 180° 5A 3 or 4 4 OUTPUTs 6 - - VCC VCC GND 120° BOTH CHANNELS 240° 2B - 3-PHASE 7A - - VCC VCC VCC 90° BOTH CHANNELS 180° 5A or 7A - 4-PHASE 7B - - VCC VCC VCC 90° BOTH CHANNELS 180° 5A or 7A - 2 OUTPUTs (1st IC in Mode 7A) 7C - - VCC VCC VCC 90° BOTH CHANNELS 180° 3, 4 - 3 OUTPUTs (1st IC in Mode 7A) 8 Cascaded IC Operation MODEs 5A+5A+7A+5A+5A+5A/7A, No External Clock Required 12-PHASE 9 External Clock or External Logic Circuits Required for Equal Phase Interval 5, 7, 8, 9, 10, 11, or (PHASE >12) NOTE: “2ND CHANNEL WRT 1ST” is referred to as “channel 2 lag channel 1 by the degrees specified by the number in the corresponding table cells”. For example, 90° with 2ND CHANNEL WRT 1ST means channel 2 lags channel 1 by 90 degree; -60° with 2ND CHANNEL WRT 1ST means channel 2 leads channel 1 by 60 degree. 21 March 20, 2009 FN6641.0 ISL8120 CH1 UG (1ST IC) D 1-D 180° CH2 UG (1ST IC) D 90° 50% CLKOUT (1ST IC) 90° D CH1 UG (2ND IC) 180° CH2 UG (2ND IC) D 4 PHASE TIMING DIAGRAM (MODE 7A) CH1 UG (1ST IC) D 1-D 240° D CH2 UG (1ST IC) 120° CLKOUT (1ST IC) 50% 120° CH1 UG (2ND IC) 1-D D CH2 UG(2ND IC, OFF, EN2/FF2 = 0) 3-PHASE TIMING DIAGRAM (MODE 6) VCC VSEN2- VSEN2+ FB2 VMON2 CLKOUT/REFIN COMP2 700mV DIFF AMP2 UV/OV COMP2 ERROR AMP2 VREF2 = VREF CLOCK GENERATOR AND RELATIVE PHASES CONTROL CHANNEL 1 PWM CONTROL BLOCK CHANNEL 2 PWM CONTROL BLOCK FIGURE 3. SIMPLIFIED RELATIVE PHASES CONTROL 22 March 20, 2009 FN6641.0 ISL8120 Functional Description Voltage Feed-forward Other than used as a voltage monitor described in the previous section, the voltages applied to the EN/FF pins are also fed to adjust the amplitude of each channel’s individual sawtooth. The amplitude of each channel’s sawtooth is set to 1.25 times the corresponding EN/FF voltage upon its enable (above 0.8V). This helps to maintain a constant gain ( G M = VIN ⋅ D MAX ⁄ ΔV RAMP ) contributed by the modulator and the input voltage to achieve optimum loop response over a wide input voltage range. The sawtooth ramp offset voltage is 1V (equal to 0.8V*1.25), and the peak of the sawtooth is limited to VCC - 1.4V. With VCC = 5.4V, the ramp has a maximum peak-to-peak amplitude of VCC - 2.4V (equal to 3V); so the feed-forward voltage effective range is typically 3x as the ramp amplitude ranges from 1V to 3V. Initialization Initially, the ISL8120 Power-On Reset (POR) circuits continually monitor the bias voltages (PVCC and VCC) and the voltage at the EN pin. The POR function initiates soft-start operation 384 clock cycles after the EN pin voltage is pulled to be above 0.8V, all input supplies exceed their POR thresholds and the PLL locking time expires, as shown in Figure 4. The enable pin can be used as a voltage monitor and to set desired hysteresis with an internal 30µA sinking current going through an external resistor divider. The sinking current is disengaged after the system is enabled. This feature is especially designed for applications that require higher input rail POR for better undervoltage protection. For example, in 12V applications, RUP = 53.6k and RDOWN = 5.23k will set the turn-on threshold (VEN_RTH) to 10.6V and turn-off threshold (VEN_FTH) to 9V, with 1.6V hysteresis (VEN_HYS). A 384 cycle delay is added after the system reaches its rising POR and prior to the soft-start. The RC timing at the EN/FF pin should be sufficiently small to ensure that the input bus reaches its static state and the internal ramp circuitry stabilizes before soft-start. A large RC could cause the internal ramp amplitude not to synchronize with the input bus voltage during output start-up or when recovering from faults. It is recommended to use open drain or open collector to gate this pin for any system delay, as shown in Figure 5. During shutdown or fault conditions, the soft-start is reset quickly while UGATE and LGATE change states immediately (<100ns) upon the input drop below falling POR. HIGH = ABOVE POR; LOW = BELOW POR VCC POR PVCC POR EN1/FF1 POR 384 Cycles AND SOFT-START OF CHANNEL 1 The multiphase system can immediately turn off all ICs under fault conditions of one or more phases by pulling all EN/FF pins low. Thus, no bouncing occurs among channels at fault and no single phase could carry all current and be over stressed. PLL LOCKING VCC POR PVCC POR 384 Cycles AND SOFT-START OF CHANNEL 2 EN2/FF2 POR FIGURE 4. SOFT-START INITIALIZATION LOGIC V EN_HYS R UP = ----------------------------I EN_HYS R •V UP EN_REF R DOWN = --------------------------------------------------------------V EN_FTH – V EN_REF VCC GRAMP = 1.25 V EN_FTH = V EN_RTH – V EN_HYS VCC - 1.4V ΔV RAMP = LIMIT(V CC_FF × G RAMP , VCC - 1.4V - V RAMP_OFFSET ) ∑ 0.8V VCC_FF UPPER LIMIT LIMITER SAWTOOTH AMPLITUDE (ΔVRAMP) VIN VRAMP_OFFSET = 1.0V LOWER LIMIT (RAMP OFFSET) 0.8V RUP SYSTEM DELAY RDOWN EN/FF 384 Clock Cycles SOFT-START IEN_HYS = 30µA OV, OT, OC, AND PLL LOCKING FAULTS (ONLY FOR EN/FF1) FIGURE 5. SIMPLIFIED ENABLE AND VOLTAGE FEEDFORWARD CIRCUIT 23 March 20, 2009 FN6641.0 ISL8120 VIN ISL8120 R VOUT ISL8120 RUP 2-PHASE SS Settling at VREF + 100mV FIRST PWM PULSE 2-PHASE EN/FF1 EN/FF1 EN/FF2 EN/FF2 0.0V 1280 t SS = ------------F SW -100mV RDOWN V EN_HYS = ---------------------------------------------------------UP I ⋅N EN_HYS PHASE 384 t SS_DLY ≈ -----------F SW FIGURE 6. TYPICAL 4-PHASE WITH FAULT HANDSHAKE FIGURE 7. SOFT-START WITH VOUT = 0V While EN/FF is pulled to ground, a constant voltage (0.8V) is fed into the ramp generator to maintain a minimum peak-to-peak ramp. FIRST PWM PULSE SS Settling at VREF + 100mV VOUT UV Since the EN/FF pins are pulled down under fault conditions, the pull-up resistor (RUP) should be scaled to sink no more than 5mA current from EN/FF pin. Essentially, the EN/FF pins cannot be directly connected to VCC. -100mV FIGURE 8. SOFT-START WITH VOUT = UV Soft-start The ISL8120 has two independent digital soft-start circuitry with fixed 1280 switching cycles. The soft-start time is inversely proportional to the switching frequency and is determined by the 1280-cycle digital counter. Refer to Figure 7. The full soft-start time from 0V to 0.6V can be estimated using Equation 1. 1280 t SS = ------------f SW (EQ. 1) The ISL8120 has the ability to work under a pre-charged output (see Figure 8). The output voltage would not be yanked down during pre-charged start-up. If the pre-charged output voltage is greater than the final target level but prior to 113% setpoint, the switching will not start until the output voltage reduces to the target voltage and the first PWM pulse is generated (see Figure 9). The maximum allowable pre-charged level is 113%. If the pre-charged level is above 113% but below 120%, the output will hiccup between 113% (LGATE turns on) and 87% (LGATE turns off) while EN/FF is pulled low. If the pre-charged load voltage is above 120% of the targeted output voltage, then the controller will be latched off and not be able to power-up. OV = 113% FIRST PWM PULSE VOUT TARGET VOLTAGE FIGURE 9. SOFT-START WITH VOUT BELOW OV BUT ABOVE FINAL TARGET VOLTAGE Power-Good CHANNEL 1 UV/OV CHANNEL 2 UV/OV END OF SS1 END OF SS2 SS1_PERIOD PGOOD AND OR AND SS2_PERIOD +20% +13% VMON1, 2 For above-target level pre-charged start-up, the output voltage would not change until the end of the soft-start. If the initial dip is below the UV level, the LGATE could be turned off. In such an event, the body-diode drop of the low-side FET will be sensed and could potentiality cause an OCP event for rDS(ON) current sensing applications. +9% VREF -9% -13% PGOOD PGOOD latch off after 120% OV FIGURE 10. POWER-GOOD THRESHOLD WINDOW 24 March 20, 2009 FN6641.0 ISL8120 FORCE LGATE1 HIGH conditions of EN/FF = LOW and the output voltage above 113% (all VMON pins and EN pins are tied together) and turns off after the output drops below 87%. Thus, in a high phase count application (Multiphase Mode), all cascaded ICs can latch off simultaneously via the EN pins (EN pins are tied together in multiphase mode), and each IC shares the same sink current to reduce the stress and eliminate the bouncing among phases. FORCE LGATE2 HIGH The UV functionality is not enabled until the end of soft-start. In a UV event, if the output drops below -13% of the target level due to some reason (cases when EN/FF is not pulled low) other than OV, OC, OT, and PLL faults, the lower MOSFETs will turn off to avoid any negative voltage ringing. VMON1 113% 87% OR AND EN/FF1 VMON1>120% OR AND multiphase MODE = HIGH VMON2 113% 87% AND OR EN/FF2 VMON2 > 120% 120% FIGURE 11. FORCE LGATE HIGH LOGIC Both channels share the same PGOOD output. Either of the channels indicating out-of-regulation will pull-down the PGOOD pin. The Power-Good comparators monitor the voltage on the VMON pins. The trip points are shown in Figure 10. PGOOD will not be asserted until after the completion of the soft-start cycle of both channels. If Channels 1 or 2 are not used, the Power-Good can stay in operation by connecting 2 channels’ VMON pins together. The PGOOD pulls low upon both EN/FF’s disabling it if one of the VMON pins’ voltage is out of the threshold window. PGOOD will not pull low until the fault presents for three consecutive clock cycles. In Dual/DDR application, if the turn-off channel pre-charges its VMON within the PGOOD threshold window, it could indicate Power-Good, however, the PGOOD signal can pull low with an external PNP or PMOS transistor via the EN/FF of the corresponding off channel. Overvoltage and Undervoltage Protection The Overvoltage (OV) and Undervoltage (UV) protection circuitry monitor the voltage on the VMON pins. OV protection is active from the beginning of soft-start. An OV condition (>120%) would latch IC off (the high-side MOSFET to latch off permanently; the low-side MOSFET turns on immediately at the time of OV trip and then turns off permanently after the output voltage drops below 87%). The EN/FF and PGOOD are also latched low at OV event. The latch condition can be reset only by recycling VCC. In Dual/DDR mode, each channel is responsible for its own OV event with the corresponding VMON as the monitor. In multiphase mode, both channels respond simultaneously when either triggers an OV event. There is another non-latch OV protection (113% of target level). At the condition of EN/FF low and the output over 113% OV, the lower side MOSFET will turn on until the output drops below 87%. This is to protect the overall power trains in case of only one channel of a multiphase system detecting OV. The low-side MOSFET always turns on at the 25 VOUT 3 CYCLES PGOOD 3 CYCLES UV OV LATCH UGATE AND EN/FF LATCH LOW FIGURE 12. PGOOD TIMING UNDER UV AND OV PRE-POR Overvoltage Protection (PRE-POR-OVP) When both the VCC and PVCC are below PORs (not including EN POR), the UGATE is low and LGATE is floating (high impedance). EN/FF has no control on LGATE when below PORs. When above PORs, the LGATE would not be floating but toggling with its PWM pulses. An internal 10kΩ resistor, connected in between PHASE and LGATE nodes, implements the PRE-POR-OVP circuit. The output of the converter that is equal to phase node voltage via output inductors is then effectively clamped to the low-side MOSFET’s gate threshold voltage, which provides some protection to the microprocessor if the upper MOSFET(s) is shorted during start-up, shutdown, or normal operations. For complete protection, the low-side MOSFET should have a gate threshold that is much smaller than the maximum voltage rating of the load. The PRE-POR-OVP works against pre-biased start-up when pre-charged output voltage is higher than the threshold of the low-side MOSFET, however, it can be disabled by placing a 2k resistor from LGATE to ground. Over-Temperature Protection (OTP) When the junction temperature of the IC is greater than +150°C (typically), both EN/FF pins pull low to inform other cascaded channels via their EN/FF pins. All connected EN/FFs stay low and release after the IC’s junction temperature drops below +125°C (typically), with a +25°C hysteresis (typical). March 20, 2009 FN6641.0 ISL8120 Current Loop where IL is the inductor DC current, DCR is its DC resistance, and tMIN_OFF is 350ns. When the ISL8120 operates in 2-phase mode, the current control loop keeps the channel’s current in balance. After 175ns blanking period with respect to the falling edge of the PWM pulse of each channel, the voltage developed across the DCR of the inductor, rDS(ON) of the low-side MOSFETs, or a precision resistor, is filtered and sampled for 175ns. The current (ICS1/ICS2) is scaled by the RISEN resistor and provides feedback proportional to the average output current of each channel. For low-side MOSFET rDS(ON) sensing, the ICS can be derived from Equation 3: V OUT ⎛ ⎞ 1–D ⎜ IL + ---------------- • ⎛⎝ ---------------- – t MIN_OFF⎞⎠ ⎟ • r DS ( ON ) L 2F ⎝ ⎠ SW ICS = -------------------------------------------------------------------------------------------------------------------------RISEN In multiphase mode (VSEN2- pulled high), the scaled output currents from both active channels are combined to create an average current reference (IAVG) which represents average current of both channel outputs as calculated in Equation 4. For DCR sensing, the sampling current ICS can be derived from Equation 2: V OUT ⎛ ⎞ 1–D ⎜ IL + ---------------- • ⎛⎝ ---------------- – t MIN_OFF⎞⎠ ⎟ • DCR L 2F SW ⎝ ⎠ ICS = ----------------------------------------------------------------------------------------------------------------RISEN ICS1 + ICS2 IAVG = ----------------------------------2 (EQ. 2) DCR SENSING IOUT1 IOUT1 L1 C IOUT2 PHASE1 L1 DCR1 (EQ. 4) rDS(ON) SENSING VOUT PHASE1 VOUT (EQ. 3) VOUT PHASE2 DCR2 DCR1 R R L2 C RISEN1 RISEN2 RISEN1 ISEN1B ISEN1A ISEN2A ISEN1A ISEN1B VCC ISEN2B DCR2 AMP DCR1 AMP ICS2 ICS1 700mV VSEN2- CHANNEL 1 PWM CONTROL BLOCK VSEN2+ E/A - IAVG_CS +15µA ISHARE CHANNEL 1 CURRENT CORRECTION BLOCK + + - ∑ ∑ 2 + IAVG + - ICSH_ERR CURRENT SHARE BLOCK CHANNEL 2 CURRENT CORRECTION BLOCK CHANNEL 2 PWM CONTROL BLOCK IAVG_CS ISET CHANNEL 1 IAVG_CS +15µA RISET 1.2V AVG_OC COMP ITRIP=108μA SOFT-START & FAULT LOGIC 7 CYCLES DELAY CHANNEL 2 SOFT-START & FAULT LOGIC OC2 COMP VISHARE 7 CYCLES DELAY IAVG = (ICS1 + ICS2) / 2 ITRIP=108µA OC1 COMP IAVG_CS = IAVG or ICS1 ICSH_ERR = (VISARE - VISET)/GCS FIGURE 13. SIMPLIFIED CURRENT SAMPLING AND OVERCURRENT PROTECTION 26 March 20, 2009 FN6641.0 ISL8120 The signal IAVG is then subtracted from the individual channel’s scaled current (ICS1 or ICS2) to produce a current correction signal for each channel. The current correction signal keeps each channel’s output current contribution balanced relative to the other active channel. undershoot/overshoot during load transient and start-up. C is typically set to 0.1µF or higher, while R is calculated with Equation 5. For multiphase operation, the share bus (VISHARE) represents the average current of all active channels and compares with each IC’s average current (IAVG_CS equals to IAVG or ICS1 depending upon the configuration, represented by VISET) to generate current share error signal (ICS_ERR) for each individual channel. Each current correction signal is then subtracted from the error amplifier output and fed to the individual channel PWM circuits. Figure 13 shows a simple and flexible configuration for both rDS(ON) and DCR sensing. L R = -----------------------C • DCR (EQ. 5) Current Share Control in Multiphase Single Output The IAVG_CS is the average current of both channels (IAVG, 2-phase mode) or only Channel 1 (ICS1, any other modes). ISHARE and ISET pins source a copy of IAVG_CS with 15µA offset, for example, the full-scale will be 123µA. If one single external resistor is used as RISHARE connecting the ISHARE bus to ground for all the ICs in parallel, RISHARE should be set equal to RISET/NCTRL (where NCNTL is the number of the ISL8120 controllers in parallel or multiphase operations), and the share bus voltage (VISHARE) set by the RISHARE represents the average current of all active channels. Another way to set RISHARE is to put one resistor in each IC’ s ISHARE pin and use the same value with RISET ( RISHARE = RISET), in which case the total equivalent resistance value is also RISET/NCTRL. The voltage (VISET) set by RISET represents the average current of the corresponding device and compared with the share bus (VISHARE). The current share error signal (ICSH_ERR) is then fed into the current correction block to adjust each channel’s PWM pulse accordingly. When both channels operate independently, the average function is disabled and generates zero average current (IAVG = 0), and the current correction block of Channel 2 is also disabled. The IAVG_CS is the Channel 1 current ICS1. The Channel 1 makes any necessary current correction by comparing its channel current (represented by VISET) with the share bus (VISHARE). When the share bus does not connect to other ICs, the ISET and ISHARE pins can be shorted together and grounded via a single resistor to ensure zero share error. Note that the common mode input voltage range of the current sense amplifiers is VCC - 1.8V. Therefore, the rDS(ON) sensing should be used for applications with output voltage greater than VCC - 1.8V. For example, an application of 3.3V output is suggested to use rDS(ON) sensing. The current share function provides at least 10% overall accuracy between ICs, 5% within the IC when using a 1% resistor to sense a 10mV signal. The current share bus works for up to 12-phase. In addition, the R-C network components (for DCR sensing) are selected such that the RC time constant matches the inductor L/DCR time constant. Otherwise, it could cause ERROR AMP 1 ERROR AMP 2 ICS1 IAVG_CS CURRENT MIRROR BLOCK SHARE BUS ISHARE RISHARE - ∑ - + + - ∑ VERROR1 ICS2 IAVG_CS ICSH_ERR CURRENT MIRROR BLOCK ∑ + - + - ∑ VERROR2 ICSH_ERR VCC 700mV IAVG = (ICS1 + ICS2) / 2 IAVG_CS = IAVG or ICS1 ISET VSEN2- IDROOP + 15µA = IAVG_CS + 15µA = ISET = ISHARE RISET RISHARE=RISET/NCTRL FIGURE 14. SIMPLIFIED CURRENT SHARE AND INTERNAL BALANCE IMPLEMENTATION 27 March 20, 2009 FN6641.0 ISL8120 For multiphase implementation, one single error amplifier should be used for the voltage loop. Therefore, all other channels’ error amplifiers should be disabled with their corresponding VSEN- pulled to VCC, as shown in Figure 16. is combined with RCSR to determine the current sharing regulation range. The generated correction voltage on RCSR is suggested to be within 5% of VREF (0.6V) to avoid fault triggering of UV/OV and PGOOD during dynamic events. Current Share Control Loop in Multi-Module with Independent Voltage Loop There are basically two options for the configuration of the communication wires between the modules. Each of option has its own unique features. The power module controlled by ISL8120 with its own voltage loop can be paralleled to supply one common output load with its integrated Master-Slave current sharing control, as shown in “Typical Application VIII (Multiple Power Modules in Parallel with Current Sharing Control)” on page 11. A resistor RCSR needs to be inserted between VSEN1- pin and the lower resistor of the voltage sense resistor divider for each module. With this resistor, the correction current sourcing from VSEN1- pin will create a voltage offset to maintain even current sharing among modules. The recommended value for the VSEN1- resistor RCSR is 100Ω and it should not be large in order to keep the unity gain amplifier input pin impedance compatibility. The maximum source current from VSEN1- pin is 350µA, which One option is to synchronize all the modules where the system has 3 analog signal communication wires (CLKOUTSYNC, ISHARE, EN/FF). In this option, all the modules are synchronized and the phase shift can also be configured to optimal to reduce the input current ripple by interleaving effects. The connections of these three wires allows the system to be started at the same time and achieve good current balance in start-up without overcurrent trip. To have different phase shift, each module has different circuitry configuration to program the phase shift, thus to make only one standard module is difficult. ISHARE VCC ISL8120 R1 1k COMP GND R4 10k R3 10k Q2 Q1 Q3 R2 3.3k ISHARE BUS GND VOUT MODULE 1 GND ISHARE VCC ISL8120 R1 1k COMP R4 10k R3 10k Q1 Q2 Q3 R2 3.3k ISHARE BUS GND GND MODULE 2 Q1: MMBT3904 Q2: MMBT3904 Q3: 2N7002 FIGURE 15. SINGLE COMMUNICATION WIRE CONNECTION 28 March 20, 2009 FN6641.0 ISL8120 VCC VSEN1/2- COM1/2 VSEN2- ISET ISET ISL81201 VSEN1/2- COM1/2 COM1/2 VSEN1+ ISL81202 ISET ISL81203 VSEN1RISET1 ISHARE ISHARE ISHARE RISET2 RISHARE1 RISHARE2 RISET3 RISHARE3 SHARE BUS RISHARE_ = RISET_ FIGURE 16. SIMPLIFIED 6-PHASE SINGLE OUTPUT IMPLEMENTATION The second option for multi-module parallel system is to have only one signal (ISHARE) wire connection. The signal wire connection scheme is targeted for a N+1 system, where each module is a standard one that can be paralleled to build up power systems with different capacity, and each module can start-up at different time, and each module can be shut down and removed without the system shutdown. Figure 15 shows some extra circuits needed for such a parallel module system (each module with independant voltage feedback loop where only one analog signal (ISHARE) wire is connected between the module) besides the circuits shown in “Typical Application VIIII (4 Outputs Operation with DCR Sensing)” on page 13. The circuitry shown in Figure 15 is to ensure the successful start-up of the system with the individual module starting up at different time. With this circuitry, each module’s local ISHARE signal is connected to the system share bus only when it starts switching (finishing of pre-biased start-up). In addition, when the module is shut off, its ISHARE signal will be removed from the ISHARE bus. The validated signal transistors shown in Figure 15 are: MMBT3904 for Q1 and Q2; 2N7002 for Q3. With the circuits of Figure 15 implemented, the system can also be further implemented with the CLKOUT-SYNC connection to have the modules synchornized and phaseshifted, which is the third option of system configuration. However, the lose of CLKOUT signal will cause the shutdown of the other module receiving the signal. Compared with the second option (single wire (ISHARE) connection), this option has one more wire connection, but all the modules are synchronized and phase-shifted. In summary, the communication wire connection in parallel systems offers flexibility. Each configuration option has its own unique features. The selection of the connections of the conmmunication wire should be based upon evaluation of the priorities of system requirements and features, such as reliability, number of wire connections, synchronizations and fault tolerance, etc. 29 In dual mode, the current sharing block for current sharing of modules with independant voltage loop is disabled. Overcurrent Protection The OCP function is enabled at start-up. When both channels operate independently, the average function is disabled and generates zero average current (IAVG = 0). The Channel 2 current (ICS2) is compared with ITRIP (108µA) as its own independent overcurrent protection and the 7 clock cycles delay is bypassed. The Channel 1’s current (ICS1) plus 15µA offset forms a voltage (VISHARE) with an external resistor RISHARE and compares with a precision 1.2V threshold for OCP; while the 108µA OCP comparator with 7-cycle delay is also activated. In multiphase operation, the VISHARE represents the average current of all active channels and compares with the ISHARE pin precision 1.2V threshold to determine the overcurrent condition. At the same time, each channel has additional overcurrent trip point at 108µA with 7-cycle delay for phase overcurrent protection. This scheme helps protect against loss of channel(s) in multi-phase mode so that no single channel could carry more than 108µA in such event. See Figure 13. Note that it is not necessary for the RISHARE to be scaled to trip at the same level as the 108µA OCP comparator if the application allows. Typically the ISHARE pin average current protection level should be higher than the phase current protection level. For instance, when Channel 1 operates independently, the OC trip set by 1.2V comparator can be lower than 108µA trip point as shown in Equation 6. ⎛ I OC V OUT ⎛ 1 – D ⎞ ⎜ ---------- + ---------------- • ⎝ ---------------- – t MIN_OFF⎞⎠ ⎟ • DCR L 2F SW ⎝ N ⎠ R ISEN1 = ---------------------------------------------------------------------------------------------------------------------I TRIP 1.2V R ISHARE = --------------I TRIP (EQ. 6) R ISET = R ISHARE ⋅ N CNTL where N is the number of phases; NCNTL is the number of the ISL8120 controllers in parallel or multiphase operations; March 20, 2009 FN6641.0 ISL8120 ITRIP = 108µA; IOC is the load overcurrent trip point; tMIN_OFF is the minimum Ugate turn off time that is 350ns; RISHARE in Equation 6 represents the total equivalent resistance in ISHARE pin bus of all ICs in multiphase or module parallel operation. 2.65V TO 5.6V 2Ω VIN Z1 Z2 5V FIGURE 17. INTERNAL REGULATOR IMPLEMENTATION The LDO is capable of supplying 250mA with regulated 5.4V output. In 3.3V input applications, when the VIN pin voltage is 3V, the LDO can still supply 150mA while maintaining LDO output voltage higher than VCC falling threshold to keep IC operating. Figure 18 shows the LDO voltage drop under different load current. However, its thermal capability should not be exceeded. The power dissipation inside the IC could be estimated with Equation 7. 6.0 5.5 5.0 PVCC (V) Internal Series Linear and Power Dissipation 30 PVCC VCC When OCP is triggered, the controller pulls EN/FF low immediately to turn off UGATE and LGATE. The VIN pin is connected to PVCC with an internal series linear regulator. The PVCC and VIN pins should have the recommended bypass ceramic capacitors (10µF) connected to GND for proper operation. The internal linear regulator’s input (VIN) can range between 3V to 22V. PVCC pin is the output of the internal linear regulator and it provides power for both the internal MOSFET drivers through the PVCC pin. VCC pin is the bias input for the IC small signal analog circuitry. By connecting PVCC to VCC pin, the internal linear regulator supplies bias power to VCC. The VCC pin should be connected to the PVCC pin with an RC filter to prevent high frequency driver switching noise from the analog circuitry. When VIN drops below 5.0V, the pass element will saturate; PVCC will track VIN with a dropout of the linear regulator. When used with an external 5V supply, the VIN pin is recommended to be tied directly to PVCC. 10µF 1µF For the RISEN chosen for OCP setting, the final value is usually higher than the number calculated from Equation 6. The reason of which is practical especially for low DCR applications since the PCB and inductor pad soldering resistance would have large effects in total impedance, affecting the DCR voltage to be sensed. For overload and hard short condition, the overcurrent protection reduces the regulator RMS output current much less than full load by putting the controller into hiccup mode. A delay time, equal to 3 soft-start intervals, is inserted to allow the disturbance to be cleared out. After the delay time, the controller then initiates a soft-start interval. If the output voltage comes up and returns to the regulation, PGOOD transitions high. If the OC trip is exceeded during the soft-start interval, the controller pulls EN/VFF low again. The PGOOD signal will remain low and the soft-start interval will be allowed to expire. Another soft-start interval will be initiated after the delay interval. If an overcurrent trip occurs again, this same cycle repeats until the fault is removed. 3V TO 26.4V PVCC @ 250mA + Iq PVCC @ 100mA + Iq 4.5 4.0 PVCC @ 140mA + Iq 3.5 3.0 2.5 2.0 2.5 Iq IS AROUND 15mA 3.0 3.5 4.0 4.5 5.0 5.5 VIN PIN VOLTAGE (V) 6.0 6.5 7.0 FIGURE 18. PVCC vs VIN VOLTAGE P IC = ( VIN – PVCC ) ⋅ I VIN + P DR (EQ. 7) ⎛ Q G1 • N Q1 Q G2 • N Q2⎞ I VIN = ⎜ ------------------------------ + ------------------------------⎟ • PVCC • F SW + I Q_VIN V GS2 ⎠ ⎝ V GS1 March 20, 2009 FN6641.0 ISL8120 (EQ. 8) P DR = P DR_UP + P DR_LOW R HI1 R LO1 ⎛ ⎞ P Qg_Q1 P DR_UP = ⎜ -------------------------------------- + ----------------------------------------⎟ • --------------------R + R R + R 2 ⎝ HI1 EXT1 LO1 EXT1⎠ R HI2 R LO2 ⎛ ⎞ P Qg_Q2 P DR_LOW = ⎜ -------------------------------------- + ----------------------------------------⎟ • --------------------R + R R + R 2 ⎝ HI2 EXT2 LO2 EXT2⎠ Q G1 • PVCC 2 P Qg_Q1 = --------------------------------------- • F SW • N Q1 V GS1 R GI2 R EXT2 = R G2 + ------------N Q2 where the gate charge (QG1 and QG2) is defined at a particular gate to source voltage (VGS1and VGS2) in the corresponding MOSFET datasheet; IQ_VIN is the driver’s total quiescent current with no load at drive outputs; NQ1 and NQ2 are number of upper and lower MOSFETs, respectively. To keep the IC within its operating temperature range, an external power resistor could be used in series with VIN pin to bring the heat out of the IC, or and external LDO could be used when necessary. BOOT D CGD RHI1 RLO1 G UGATE RG1 CDS RGI1 CGS Q1 S PHASE FIGURE 19. TYPICAL UPPER-GATE DRIVE TURN-ON PATH PVCC D CGD RHI2 LGATE RLO2 G RG2 CDS RGI2 CGS Q2 S GND FIGURE 20. TYPICAL LOWER-GATE DRIVE TURN-ON PATH 31 SWITCHING FREQUENCY (kHz) Q G2 P Qg_Q2 = --------------------------------------- • F SW • N Q2 V GS2 PVCC The Oscillator is a sawtooth waveform, providing for leading edge modulation with 350ns minimum dead time. The oscillator (Sawtooth) waveform has a DC offset of 1.0V. Each channel’s peak-to-peak of the ramp amplitude is set proportional the voltage applied to its corresponding EN/FF pin. See “Voltage Feed-forward” on page 23. 1,600 • PVCC 2 R GI1 R EXT2 = R G1 + ------------N Q1 Oscillator 1,400 1,200 1,000 800 600 400 200 0 20 40 60 80 100 120 140 160 180 200 220 240 260 R_FS (kΩ ) FIGURE 21. RFS vs SWITCHING FREQUENCY Frequency Synchronization and Phase Lock Loop The FSYNC pin has two primary capabilities: fixed frequency operation and synchronized frequency operation. By tying a resistor (RFSYNC) to GND from the FSYNC pin, the switching frequency can be set at any frequency between 150kHz and 1.5MHz. The frequency setting curve shown in Figure 21 is provided to assist in selecting the correct value for RFSYNC. By connecting the FSYNC pin to an external square pulse waveform (such as the CLOCK signal, typically 50% duty cycle from another ISL8120), the ISL8120 will synchronize its switching frequency to the fundamental frequency of the input waveform. The maximum voltage to the FSYNC pin is VCC + 0.3V. The Frequency Synchronization feature will synchronize the leading edge of CLKOUT signal with the falling edge of Channel 1’s PWM clock signal. The CLKOUT is not available until the PLL locks. The locking time is typically 130µs for FSW = 500kHz. EN/VFF1 is released for a soft-start cycle until the FSYNC stabilized and the PLL is in locking. The PLL circuits control only EN/FF1, and control Channel 2’s soft-start instead of EN/FF2. Therefore, it is recommended to connect all EN/FF pins together in multiphase configuration. The loss of a synchronization signal for 13 clock cycles causes the IC to be disabled until the PLL returns locking, at which point a soft-start cycle is initiated and normal operation resumes. Holding FSYNC low will disable the IC. March 20, 2009 FN6641.0 ISL8120 Differential Amplifier for Remote Sense As some applications will not need the differential remote sense, the output of the remote sense buffer can be disabled and be placed in high impedance by pulling VSEN- within 700mV of VCC. In such an event, the VMON pin can be used as an additional monitor of the output voltage with a resistor divider to protect the system against single point of failure, which occurs in the system using the same resistor divider for the UV/OV comparator and the output regulation. The resistor divider ratio should be the same as the one for the output regulation so that the correct voltage information is provided to the OV/UV comparator. Figure 23 shows the differential sense amplifier can be directly used as a monitor without pulling VSEN- high. VSEN+ 20k RDIF = 500k 20k VSEN- 20k 20k FIGURE 22. EQUIVALENT DIFFERENTIAL AMPLIFER The differential remote sense buffer has a precision unity gain resistor matching network, which has a ultra low offset of 1mV. This true remote sensing scheme helps compensate the droop due to load on the positive and negative rails and maintain the high system accuracy of ±0.6%. DDR and Dual Mode Operation If the CLKOUT/REFIN is less than 800mV, an external soft-start ramp (0.6V) can be in parallel with the Channel 2’s internal soft-start ramp for DDR/tracking applications (DDR Mode). The output of the remote sense buffer is connected directly to the internal OV/UV comparator. As a result, a resistor divider should be placed on the input of the buffer for proper regulation, as shown in Figure 24. The VMON pin should be connected to the FB pin by a standard feedback network. The output voltage (typical VTT output) of Channel 2 tracks with the input voltage (typical VDDQ*(1+k) from Channel 1) at the CLKOUT/REFIN pin. As for the external input signal and internal reference signal (ramp and 0.6V), the one with the lowest voltage will be the one to be used as the reference comparing with FB signal. So in DDR configuration, VTT channel should start-up later after its internal soft-start ramp in which way the VTT will track the voltage on REFIN pin derived from VDDQ. This can be achieved by adding more filtering at EN//FF1 compared with EN/FF2. Since the input impedance of VSEN+ pin in respect to VSEN- pin is about 500kΩ, it is highly recommended to include this impedance into calculation and use 100Ω or less for the lower leg (ROS) of the feedback resistor divider to optimize system accuracy. Note that any RC filter at the inputs of the differential amplifier will contribute as a pole to the overall loop compensation. VOUT RFB RFB ROS ROS ZCOMP VSEN+ VCC GND VSEN- PGOOD VMON FB COMP 700mV GAIN=1 VREF OV/UV COMP ERROR AMP PGOOD FIGURE 23. DUAL OUTPUT VOLTAGE SENSE FOR SINGLE POINT OF FAILURE PROTECTION 32 March 20, 2009 FN6641.0 ISL8120 VSENSE- (REMOTE) 10Ω VOUT (LOCAL) VSENSE+ (REMOTE) CSEN GND (LOCAL) 10Ω RFB ROS ZCOMP ZFB VSEN- VCC VSEN+ PGOOD VMON FB COMP 700mV GAIN=1 VREF OV/UV COMP ERROR AMP PGOOD FIGURE 24. SIMPLIFIED REMOTE SENSING IMPLEMENTATION Since the UV/OV comparator uses the same internal reference 0.6V, to guarantee UV/OV and Pre-charged start-up functions of Channel 2, the target voltage derived from Channel 1 (VDDQ) should be scaled close to 0.6V, and it is suggested to be slightly above (+2%) 0.6V with an external resistor divider, which will have Channel 2 use the internal 0.6V reference after soft-start. Any capacitive load at REFIN pin should not slow down the ramping of this input 150mV lower than the Channel 2’ internal ramp. Otherwise, the UV protection could be fault triggered prior to the end of the soft-start. The start-up of Channel 2 can be delayed to avoid such situation happening, if high capacitive load presents at REFIN pin for noise decoupling. During shutdown, Channel 2 will follow Channel 1 until both channels drops below 87%, at which point both channels enter UV protection zone. Depending on the loading, Channel 1 might drop faster than Channel 2. To solve this race condition, Channel 2 can either power up from Channel 1 or bridge the Channel 1 with a high current Schottky diode. If the system requires to shutdown both channels when either has a fault, tying EN/FF1 and EN/FF2 will do the job. In DDR mode, Channel 1 delays 60° over Channel 2. In Dual mode, depending upon the resistor divider level of REFIN from VCC, the ISL8120 operates as a dual-PWM controller for two independent regulators with a phase shift, as shown in Table 2. The phase shift is latched as VCC raises above POR and cannot be changed on the fly. TABLE 2. MODE DECODING REFIN RANGE PHASE for CHANNEL REQUIRED 2 WRT CHANNEL 1 REFIN DDR <29% of VCC -60° 0.6V Dual 29% to 45% of VCC 0° 37% VCC Dual 45% to 62% of VCC 90° 53% VCC Dual 62% to VCC 180° VCC 33 VCC VDDQ VSEN2- PHASE-SHIFTED CLOCK ISL8120 STATE MACHINE k*R CLKOUT/REFIN 700mV R VTT k = ------------ – 1 0.6V Internal SS 0.6V FB2 E/A2 FIGURE 25. SIMPLIFIED DDR IMPLEMENTAION Internal Reference and System Accuracy The internal reference is set to 0.6V. Including bandgap variation and offset of differential and error amplifiers, it has an accuracy of ±0.6% over commercial temperature range, and 0.9% over industrial temperature range. While the remote sense is not used, its offset (VOS_DA) should be included in the tolerance calculation. Equations 9 and 10 show the worst case of system accuracy calculation. VOS_DA should set to zero when the differential amplifier is in the loop, the differential amplifier’s input impedance (RDIF) is typically 500kΩ with a tolerance of 20% (RDIF%) and can be neglected when ROS is less than 100Ω. To set a precision setpoint, ROS can be scaled by two paralleled resistors. Figure 26 shows the tolerance of various output voltage regulation for 1%, 0.5%, and 0.1% feedback resistor March 20, 2009 FN6641.0 ISL8120 dividers. Note that the farther the output voltage setpoint away from the internal reference voltage, the larger the tolerance; the lower the resistor tolerance (R%), the tighter the regulation. (EQ. 9) 1 R OSMAX = ----------------------------------------------------------------------------------------------------1 1 ---------------------------------------- + --------------------------------------------------R OS ⋅ ( 1 + R% ) R DIF ⋅ ( 1 + R DIF % ) R FB ⋅ ( 1 – R% )⎞ ⎛ %max = ( Vref ⋅ ( 1 – Ref% ) – V OS_DA ) ⋅ ⎜ 1 + ----------------------------------------⎟ R OSMIN ⎠ ⎝ (EQ. 10) 1 R OSMIN = ----------------------------------------------------------------------------------------------1 1 --------------------------------------- + ------------------------------------------------R OS ⋅ ( 1 – R % ) R DIF ⋅ ( 1 – R DIF % ) R% = 1% 2.0 1.5 OUTPUT REGULATION (%) R FB ⋅ ( 1 – R% )⎞ ⎛ %min = ( Vref ⋅ ( 1 – Ref% ) – V OS_DA ) ⋅ ⎜ 1 + ----------------------------------------⎟ R OSMAX ⎠ ⎝ 2.5 0.5% 1.0 0.1% 0.5 0.0 -0.5 0.1% -1.0 0.5% -1.5 -2.0 1% -2.5 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 OUTPUT VOLTAGE (V) FIGURE 26. OUTPUT REGULATION WITH DIFFERENT RESISTOR TOLERANCE FOR Ref% = ±0.6% All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems. Intersil Corporation’s quality certifications can be viewed at www.intersil.com/design/quality Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries. For information regarding Intersil Corporation and its products, see www.intersil.com 34 April 7, 2009 ISL8120 Package Outline Drawing L32.5x5B 32 LEAD QUAD FLAT NO-LEAD PLASTIC PACKAGE Rev 2, 11/07 4X 3.5 5.00 28X 0.50 A B 6 PIN 1 INDEX AREA 6 PIN #1 INDEX AREA 32 25 1 5.00 24 3 .30 ± 0 . 15 17 (4X) 8 0.15 9 16 TOP VIEW 0.10 M C A B + 0.07 32X 0.40 ± 0.10 4 32X 0.23 - 0.05 BOTTOM VIEW SEE DETAIL "X" 0.10 C 0 . 90 ± 0.1 C BASE PLANE SEATING PLANE 0.08 C ( 4. 80 TYP ) ( ( 28X 0 . 5 ) SIDE VIEW 3. 30 ) (32X 0 . 23 ) C 0 . 2 REF 5 ( 32X 0 . 60) 0 . 00 MIN. 0 . 05 MAX. DETAIL "X" TYPICAL RECOMMENDED LAND PATTERN NOTES: 1. Dimensions are in millimeters. Dimensions in ( ) for Reference Only. 2. Dimensioning and tolerancing conform to AMSE Y14.5m-1994. 3. Unless otherwise specified, tolerance : Decimal ± 0.05 4. Dimension b applies to the metallized terminal and is measured between 0.15mm and 0.30mm from the terminal tip. 5. Tiebar shown (if present) is a non-functional feature. 6. The configuration of the pin #1 identifier is optional, but must be located within the zone indicated. The pin #1 identifier may be either a mold or mark feature. 35 March 20, 2009 FN6641.0