19-3974; Rev 0; 1/06 KIT ATION EVALU E L B AVAILA High-Speed, Dual-Phase Driver with Integrated Boost Diodes The MAX8811 2-phase gate driver controls power MOSFETs in multiphase synchronous step-down converter applications, providing up to 30A output current per phase. The MAX8811 and MAX8810A (multiphase power-supply controller) combine to provide an efficient, low-cost solution for a wide range of multiphase powersupply applications. The MAX8811 handles system input voltages up to 26V. Each MOSFET driver is capable of driving 3000pF capacitive loads with 11ns typical rise and fall times. Adaptive shoot-through protection circuitry is implemented to prevent shoot-through currents for the “highside off to low-side on” transition. A programmable delay is provided for the “low-side off to high-side on” transition. This maximizes overall converter efficiency while supporting operation with a variety of MOSFETs. The MAX8811 provides an easy upgrade path from the MAX8523 dual driver. Integrated bootstrap diodes reduce external component count, while an enable input provides flexibility for power sequencing. The MAX8811 is available in a space-saving, 16-pin QSOP. Features ♦ Dual-Phase Synchronous Buck Driver ♦ Integrated Bootstrap Diodes ♦ Up to 26V System Input Voltage ♦ 6A Peak Gate Drive Current ♦ Capable of 30A per Phase ♦ 0.4Ω/0.9Ω Low-Side, 0.7Ω/1.0Ω High-Side Drivers (typ) ♦ Typical 11ns Rise/Fall Times with 3000pF Load ♦ Adaptive Dead-Time Control ♦ User-Programmable Delay Time ♦ Enable Function with 0.04µA (typ) Quiescent Current in Shutdown ♦ Space-Saving, Lead-Free, 16-Pin QSOP Ordering Information Applications Processor Core Voltage Regulators Multiphase Buck Converters Voltage-Regulator Modules (VRMs) PART TEMP RANGE PINPACKAGE PKG CODE MAX8811EEE+ -40°C to +85°C 16 QSOP E16-4 + = Denotes lead-free package. Switching Power Supplies DC-DC Converter Modules Pin Configuration Typical Operating Circuit GATE-DRIVE SUPPLY 4.5V TO 7V 4 TOP VIEW 13 BST1 1 + POWER INPUT UP TO 26V VL1 VL2 DH1 BST1 16 BST2 DH1 2 15 DH2 LX1 LX1 3 14 LX2 DL1 VL1 4 MAX8811 DL1 5 8 13 VL2 DLY PGND1 2 1 3 OUTPUT 5 + 6 12 DL2 PGND1 6 11 PGND2 EN 7 10 PWM2 MAX8811 ON OFF DLY 8 9 PWM1 DH2 7 9 QSOP PWM CONTROL SIGNALS EN BST2 PWM1 LX2 10 PWM2 DL2 PGND2 15 16 14 12 11 ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX8811 General Description MAX8811 High-Speed, Dual-Phase Driver with Integrated Boost Diodes ABSOLUTE MAXIMUM RATINGS DLY, EN to PGND_, PWM_ to DL_..............-0.3V to (VVL_+ 0.3V) BST_ to PGND_ ............................................-0.3V to (VLX_ + 8V) BST_ to VL_ ...............................................................-1V to +30V LX_ to PGND_............................................................-1V to +28V DH_ to PGND_.........................................-0.3V to (VBST_ + 0.3V) DH_, BST_ to LX_ .....................................................-0.3V to +8V VL_ to PGND_ ..........................................................-0.3V to +8V DH_, DL_ Current ................................................. ±200mA RMS VL_ to BST_ Internal Diode Current .........................±50mA RMS PGND1 to PGND2 .................................................-0.3V to +0.3V Continuous Power Dissipation (TA = +70°C) 16-Pin QSOP (derate 8.3 mW/°C above +70°C)......666.7 mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VDLY = VEN = VBST_ = VVL_ = 6.5V, VPGND_ = VLX_ = VPWM_ = 0V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER CONDITIONS MIN TYP MAX UNITS GENERAL VL_ Input Voltage Range 4.5 LX Operating Range VL_ Undervoltage Lockout (UVLO) Supply Current (per Channel) IBST_ + IVL_ Shutdown Supply Current (per Channel) IBST_ + IVL_ VVL_ rising, 250mV hysteresis (typ) 3.25 7 V 26 V 3.8 V VPWM__= 0V 0.7 1.5 VPWM__ = VDLY = VVL_ 1.4 2 VEN = 0V, VPWM_ = 0V or VVL_ 0.04 1 VPWM_ = 0V or 7.0V, VEN = 0V or 7.0V 0.01 mA µA PWM_ Input Leakage µA Input Voltage High Threshold V Input Voltage Low Threshold 1.2 Input Threshold Hysteresis 3.5 V 20 % 0.01 µA EN Input Leakage Input Voltage High Threshold VPWM_ = 0V or 7.0V, VEN = 0V or 7.0V 0.8 V Input Voltage Low Threshold Input Voltage Hysteresis 2.6 0.5 V V DLY Delay Disable Threshold VVL_ - VDLY 2 0.8 _______________________________________________________________________________________ 1.2 V High-Speed, Dual-Phase Driver with Integrated Boost Diodes (VDLY = VEN = VBST_ = VVL_ = 6.5V, VPGND_ = VLX_ = VPWM_ = 0V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER CONDITIONS MIN TYP MAX UNITS GATE DRIVER SPECIFICATIONS VPWM_ = VVL_, sourcing current VBST_ = 6.5V, IDH_ = -0.1A 1.0 1.6 VPWM_ = 0V, sinking current VBST_ = 6.5V, IDH_ = 0.1A 0.7 1.1 VPWM_ = 0V, sourcing current VVL_ = 6.5V, IDL_= -0.1A 0.9 1.5 VPWM_ = VVL_, sinking current VVL_= 6.5V, IDL_= 0.1A 0.4 0.7 DH_ Driver Resistance Ω DL_ Driver Resistance DH_ Rise Time (trDH) VPWM_ = VVL_ VBST_ = 6.5V, 3000pF load 14 ns DH_ Fall Time (tfDH) VPWM_ = 0V VBST_ = 6.5V, 3000pF load 9 ns DL_ Rise Time (trDL) VPWM_ = 0V VVL_ = 6.5V, 3000pF load 11 ns DL_ Fall Time (tfDL) VPWM_ = VVL_ VVL_ = 6.5V, 3000pF load 8 ns DH_ Propagation Delay VPWM_ falling (tpDHf) VPWM_ = VVL _ , VDL _ falling (tpDHr) DL_ Propagation Delay VPWM_ rising (tpDLf) VPWM_ = GND, LX falling (tpDLr) 20 VBST_ = 6.5V ns 14 12 VBST_ - VLX_ = 6.5V ns 16 INTERNAL BOOST DIODE SPECIFICATIONS On-Resistance IBST_ = 40mA 6 Ω +165 °C THERMAL SHUTDOWN Thermal Shutdown Rising temperature, hysteresis = 15°C (typ) Note 1: Specifications at -40°C guaranteed by design. _______________________________________________________________________________________ 3 MAX8811 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (VVL1 = VVL2 = VEN = VDLY = 6.5V, 3000pF capacitive load, TA = +25°C, unless otherwise noted.) VL_ POWER DISSIPATION vs. LOAD CAPACITANCE 400 300 200 300 250 200 150 25 fSW = 200kHz 0 0 800 1000 3000 fS (kHz) DH RISE/FALL TIME vs. LOAD CAPACITANCE 25 14 TIME (ns) 20 15 DH FALL 3000 5000 7000 RISE AND FALL TIMES vs. TEMPERTURE VL_ SUPPLY CURRENT vs. PER-PHASE SWITCHING FREQUENCY DL RISE 10 DH FALL 8 DL FALL 4 5 1000 LOAD CAPACITANCE (pF) 6 10 fSW = 200kHz 0 DH/DL LOAD CAPACITANCE (pF) DH RISE 12 DH RISE DL 10 7000 16 MAX8811toc04 30 5000 120 VL_ SUPPLY CURRENT (mA) 600 1000 MAX8811toc05 400 DL RISE 15 5 50 200 20 100 100 0 MAX8811toc03 350 RISE/FALL TIME (ns) 500 30 MAX8811toc02 600 400 VL_ POWER DISSIPATION (mW) MAX8811toc01 VL_ POWER DISSIPATION (mW) 700 DL RISE/FALL vs. LOAD CAPACITANCE MAX8811toc06 VL_ POWER DISSIPATION vs. PER-PHASE SWITCHING FREQUENCY RISE/FALL TIME (ns) 100 80 60 40 20 2 3000pF LOAD 0 0 0 0 2000 4000 6000 8000 -40 -15 LOAD CAPACITANCE (pF) 10 35 60 85 200 600 fS (kHz) 120 MAX8811toc11 tpDHf 20 400 PROGRAMMABLE DELAY vs. RDLY MAX8811toc07 25 100 DELAY (ns) tpDLr 15 tpDHr 10 80 60 40 tpDLf 5 20 0 0 -40 -15 10 35 TEMPERATURE (°C) 4 0 TEMPERATURE (°C) PROPAGATION DELAY vs. TEMPERATURE TIME (ns) MAX8811 High-Speed, Dual-Phase Driver with Integrated Boost Diodes 60 85 0 10 20 30 40 50 60 70 80 90 100 RDLY (kΩ) _______________________________________________________________________________________ 800 1000 High-Speed, Dual-Phase Driver with Integrated Boost Diodes MAX8811toc09 MAX8811toc10 VBST_ AND VL_ WAVEFORMS SWITCHING WAVEFORMS VPWM 5V/div VLX 10V/div VL (AC-COUPLED) 500mV/div VBST (AC-COUPLED) 200mV/div VDL 5V/div VDH 5V/div VLX 10div fSW = 250kHz 1μs/div 100ns/div Pin Description PIN NAME FUNCTION 1 BST1 2 DH1 High-Side Gate-Driver Output for Phase 1. DH1 is pulled low during shutdown and UVLO. 3 LX1 Inductor Connection for Phase 1 4 VL1 Gate-Drive Supply for DL1. Connect VL1 to a 4.5V to 7V supply. VL1 must be connected to VL2 externally. Bypass the VL1/VL2 connection with a 2.2µF or larger ceramic capacitor to the power ground plane. 5 DL1 Low-Side Gate-Driver Output for Phase 1. DL1 is pulled low during shutdown and UVLO. 6 PGND1 7 EN Enable Input. Drive EN high for normal operation, or low for shutdown. 8 DLY Delay Time Setting Input. Connect a resistor from DLY to PGND1 to set the dead time between DL falling and DH rising, or connect DLY to VL1 to use the default delay. 9 PWM1 PWM Logic Input for Phase 1. DH1 is high when PWM1 is high; DL1 is high when PWM1 is low. 10 PWM2 PWM Logic Input for Phase 2. DH2 is high when PWM2 is high; DL2 is high when PWM2 is low. 11 PGND2 12 DL2 Low-Side Gate-Driver Output for Phase 2. DL2 is pulled low during shutdown and UVLO. 13 VL2 Gate-Drive Supply for DL2. Connect VL2 to a 4.5V to 7V supply. VL1 must be connected to VL2 externally. Bypass the VL1/VL2 connection with a 2.2µF or larger ceramic capacitor to the power ground plane. 14 LX2 Inductor Connection for Phase 2 15 DH2 High-Side Gate-Driver Output for Phase 2. DH2 is pulled low during shutdown and UVLO. 16 BST2 Boost Capacitor Connection for Phase 2. Connect a 0.22µF ceramic capacitor between BST2 and LX2. Boost Capacitor Connection for Phase 1. Connect a 0.22µF ceramic capacitor between BST1 and LX1. Power Ground for DL1. Connect PGND1 and PGND2 to the power ground plane at the IC. Power Ground for DL2. Connect PGND1 and PGND2 to the power ground plane at the IC. _______________________________________________________________________________________ 5 MAX8811 Typical Operating Characteristics (continued) (VVL1 = VVL2 = VEN = VDLY = 6.5V, 3000pF capacitive load, TA = +25°C, unless otherwise noted.) MAX8811 High-Speed, Dual-Phase Driver with Integrated Boost Diodes DHON DHLO BST1 DH1 LX1 DLON DLLO VL1 DL1 PGND1 PWM1 PHASE 1 EN EN LOGIC VL1 UVLO LX1 LOW DETECT MAX8811 VL2 PHASE 2 PWM2 DHON DHLO BST2 DH2 LX2 DLON DLLO VL2 DL2 PGND2 LX2 LOW DETECT Figure 1. Functional Diagram tpDHf tpDLf PWM DL tfDL tpDHr tpDLr trDL (tDLY)* LX trDH tfDH DH *WHEN RDLY IS USED, tpDHr BECOMES THE USER-PROGRAMMABLE TIME DELAY, tDLY. DRAWING IS NOT TO SCALE. Figure 2. Driver Timing Diagram 6 _______________________________________________________________________________________ High-Speed, Dual-Phase Driver with Integrated Boost Diodes Principles of Operation MOSFET Gate Drivers (DH_, DL_) DH_ is driven high when the PWM_ is high; DL_ is driven high when PWM_ is low. PWM pulsewidths under 20ns (typ) are rejected, and no switching occurs. The low-side drivers (DL_) have typical 0.9µs sourcing resistance and 0.4Ω sinking resistance, and are capable of driving 3000pF capacitive loads with 11µs typical rise and 8µs typical fall times. The high-side drivers (DH_) have typical 1.0Ω sourcing resistance and 0.7Ω sinking resistance, and are capable of driving 3000pF capacitive loads with 14µs typical rise and 9µs typical fall times. This facilitates fast switching, reducing switching losses, and makes the MAX8811 ideal for both high-frequency and high-output current applications. Shoot-Through Protection Adaptive shoot-through protection is incorporated for the switching transition after the high-side MOSFET is turned off and before the low-side MOSFET is turned on. The low-side driver is turned on when the LX voltage falls below 2.5V, or after 135ns typical delay, whichever occurs first. Furthermore, the delay time between the low-side MOSFET turn-off and high-side MOSFET turn-on can be adjusted by selecting the value of R1 (see the Setting the Dead Time section). Table 1. Components for Figure 3, 800kHz, 20A/Phase Typical Application Circuit DESIGNATION Thermal Protection Thermal-overload protection limits total power dissipation in the MAX8811. When the junction temperature exceeds +165°C, all driver outputs are held low. The IC resumes normal operation after the junction temperature cools by 15°C (typ). Boost Capacitor Selection The MAX8811 uses a bootstrap circuit to generate the supply voltages for the high-side drivers (DH_). The selected high-side MOSFET determines the appropriate boost capacitance values, according to the following equation: CBST = QGATE ΔVBST MANUFACTURER C1 AVX C2 2 x 10µF ±20%, X7R 25V capacitor 12103D106MAT2W AVX C3 2.2µF ±20%, 10V X5R capacitor GRM39X5R225K10 Murata C4, C5 0.22µF ±20%, 10V X7R capacitors GRM39X7R224K10 Murata C6–C9 100µF ±20%, 6.3V X5R capacitors C3225X5R0J107M TDK L1, L2 0.2µH, 28A inductors FDV0630R20M,1.9mΩ DCR TOKO Q1, Q3 HAT2168, 8mΩ, 30V MOSFET Renesas Q2 2 x HAT2164H, 3mΩ, 30V, MOSFET Renesas Q4 2 x HAT2164H, 3mΩ, 30V MOSFET Renesas R1 Dead-time delay programming resistor; see TOC TBD — Undervoltage Lockout (UVLO) When the voltage at the VL1/VL2 connection is below the UVLO threshold, all driver outputs are held low. This prevents switching when the supply voltage is too low for proper operation. DESCRIPTION 2 x 10µF ±20%, X7R 25V capacitor 12103D106MAT2W where QGATE is the total gate charge of the high-side MOSFET and ΔVBST is the voltage variation allowed on the high-side MOSFET drive. Choose ΔVBST = 0.1V to 0.2V when determining CBST. Low-ESR ceramic capacitors should be used. VL_ Decoupling VL1 and VL2 provide the supply voltage for the lowside drivers. The decoupling capacitors at VL_ also charge the BST capacitors during the time period when DL_ is high. Therefore, the decoupling capacitor C3 for VL_ should be large enough to minimize the ripple voltage during switching transitions. Choose the VL capacitor approximately 10 times the value of the BST capacitor value. _______________________________________________________________________________________ 7 MAX8811 Detailed Description MAX8811 High-Speed, Dual-Phase Driver with Integrated Boost Diodes Table 2. Components for Figure 4, 300kHz, 30A/Phase Typical Application Circuit DESIGNATION DESCRIPTION MANUFACTURER C1 2 x 10µF ±20%, X7R 25V capacitor 12103D106MAT2W AVX C2 2 x 10µF ±20%, X7R 25V capacitor 12103D106MAT2W AVX C3 2.2µF ±20%, 10V X5R capacitor GRM39X5R225K10 Murata 0.22µF ±20%, 10V X7R capacitors GRM39X7R224K10 Murata C4, C5 C6, C7, C8 2700µF ±20%, 6.3V capacitors MFZ series, 7mΩ max ESR Applications Information Rubycon L1, L2 T50183, 250nH inductors at 35A ±20%, 0.68mΩ DCR Falco Electronics Q1 2 x HAT2168, 8mΩ, 30V MOSFET Renesas Q2 2 x HAT2164H, 3mΩ, 30V MOSFET Renesas Q3 2 x HAT2168, 8mΩ, 30V MOSFET Renesas Q4 2 x HAT2164H, 3mΩ, 30V MOSFET Renesas Power Dissipation Power dissipation in the IC package comes mainly from switching the MOSFETs. Therefore, it is a function of both switching frequency and the total gate charge of the selected MOSFETs. The total power dissipation when both drivers are switching is given by: PIC = 2 × fS × [N × QG _ TOTAL _ HS × RHS + M x QG _ TOTAL _ LS × RHS + (RG _ HS / N) RLS ] × VPV _ + VVCC × IVCC RLS + RG _ LS / M ( Setting the Dead Time Connect DLY to VL_ for the default delay time, typically 14ns. To increase the delay between the low-side MOSFET drive turn-off and the high-side MOSFET turnon, connect a resistor from DLY to PGND1. See the Typical Operating Characteristics section for a plot of the delay time vs. resistor value. The equation for this resistor is: tDLY = 14µs + (1pF) x RDLY Avoiding dV/dt-Induced Low-Side MOSFET Turn-On At high input voltages, fast turn-on of the high-side MOSFET could momentarily turn on the low-side MOSFET due to the high dV/dt appearing at the drain of the low-side MOSFET. The high dV/dt causes a current flow 8 through the Miller capacitance (CRSS) and the input capacitance (CISS) of the low-side MOSFET. Improper selection of the low-side MOSFET that has a high ratio of CRSS/CISS makes the problem more severe. To avoid the problem, give special attention to the ratio of C RSS /C ISS when selecting the low-side MOSFET. Adding a resistor between BST_ and the BST_ capacitor slows the high-side MOSFET turn-on. Adding a capacitor from the gate to the source of the high-side MOSFET has the same effect. However, both methods are at the expense of increasing the switching losses. ) where fS is the switching frequency, QG_TOTAL_HS is the total gate charge of the selected high-side MOSFET, Q G_TOTAL_LS is the total gate charge of the selected low-side MOSFET, N is the total number of the high-side MOSFETs in parallel, M is the total number of the low-side MOSFETs in parallel, VVL is the voltage at VL, RHS is the on-resistance of the high-side MOSFET, and RG_LS is the gate resistance of the selected lowside MOSFETs. PC Board Layout The MAX8811 sources and sinks large currents to drive MOSFETs at high switching speeds. The high di/dt can cause unacceptable ringing if the trace lengths and impedances are not well controlled. The following PC board layout guidelines are recommended when designing with the MAX8811: 1) Place all decoupling capacitors as close to their respective pins as possible. 2) Minimize the high-current loops from the input capacitor, upper switching MOSFET, and low-side MOSFET back to the input capacitor negative terminal. 3) Provide enough copper area at and around the _______________________________________________________________________________________ High-Speed, Dual-Phase Driver with Integrated Boost Diodes MAX8811 GATE-DRIVE SUPPLY 4.5V TO 7V VIN = 12V C1 VL1 DH1 DLY BST1 VL2 LX1 Q1 C4 R1 L1 VOUT C6 C3 DL1 C7 C8 C9 Q2 PGND1 MAX8811 BST2 DH2 ON EN OFF C2 Q3 C5 PWM1 LX2 PWM2 DL2 L2 Q4 PGND2 PWM CONTROL SIGNALS Figure 3. 800kHz, 20A/Phase Typical Application Circuit GATE-DRIVE SUPPLY 4.5V TO 7V VIN = 12V C1 VL1 DH1 DLY BST1 VL2 LX1 Q1 C4 L1 VOUT C3 DL1 C6 Q2 C7 C8 PGND1 MAX8811 ON OFF EN C2 BST2 DH2 Q3 C5 PWM1 LX2 PWM2 DL2 PWM CONTROL SIGNALS L2 Q4 PGND2 Figure 4. 300kHz, 30A/Phase Typical Application Circuit _______________________________________________________________________________________ 9 MAX8811 High-Speed, Dual-Phase Driver with Integrated Boost Diodes switching MOSFETs and inductors to aid in thermal dissipation. gate noise. Adjacent DH_ and LX_ traces should be tightly coupled. 4) Connect PGND1 and PGND2 as close as possible to the source of the low-side MOSFETs. A sample evaluation layout is available in the MAX8811 Evaluation Kit. 5) Keep LX1 and LX2 away from sensitive analog components and nodes. Chip Information 6) Gate drive traces should be at least 20 mils wide, kept as short as possible, and tightly coupled to reduce EMI and ringing induced by high-frequency 10 PROCESS: BiCMOS ______________________________________________________________________________________ High-Speed, Dual-Phase Driver with Integrated Boost Diodes QSOP.EPS PACKAGE OUTLINE, QSOP .150", .025" LEAD PITCH 21-0055 F 1 1 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 11 © 2006 Maxim Integrated Products Boblet Printed USA is a registered trademark of Maxim Integrated Products, Inc. MAX8811 Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)