MAX8855/MAX8855A 19-0726 Rev 4 10/11 Dual, 5A, 2MHz Step-Down Regulators General Description Features 27m On-Resistance Internal MOSFETs The MAX8855/MAX8855A high-efficiency, dual step-down regulators are capable of delivering up to 5A at each out- Dual, 5A, PWM Step-Down Regulators put. The devices operate from a 2.25V to 3.6V supply, and Fully Protected Against Overcurrent, provide output voltages from 0.6V to 0.9 x V , making them Short Circuit, and Overtemperature IN ideal for on-board point-of-load applications. Total output 1% Output Accuracy Over Load, Line, error is less than 1% over load, line, and temperature. and Temperature Operates from 2.25V to 3.6V Supply The MAX8855/MAX8855A operate in PWM mode with a switching frequency ranging from 0.5MHz to 2MHz, set REFIN on One Channel for Tracking or External Reference by an external resistor. It can also be synchronized to an external clock in the same frequency range. Two Integrated Boost Diodes internal switching regulators operate 180 out-of-phase Adjustable Output from 0.6V to 0.9 x V IN to reduce the input ripple current, and consequently Soft-Start Reduces Inrush Supply Current reduce the required input capacitance. The high 0.5MHz to 2MHz Adjustable Switching, operating frequency minimizes the size of external or FSYNC Input components. High efficiency, internal dual-nMOS All-Ceramic-Capacitor Design design keeps the board cool under heavy loads. The 180 Out-of-Phase Operation Reduces Input voltage-mode control architecture and the high-band- Ripple Current width (> 15MHz typ) voltage-error amplifier allow a type Individual Enable Inputs and PWRGD Outputs III compensation scheme to be utilized to achieve fast Safe-Start into Prebiased Output response under both line and load transients, and also allow for ceramic output capacitors. Available in 5mm x 5mm Thin QFN Package Sink/Source Current in DDR Applications Programmable soft-start reduces input inrush current. Two enable inputs allow the turning on/off of each out- Ordering Information put individually, resulting in great flexibility for system- level designs. A reference input is provided to facilitate PART TEMP RANGE PIN-PACKAGE output-voltage tracking applications. The MAX8855/ MAX8855ETJ+ -40C to +85C 32 TQFN-EP* MAX8855A are available in a 32-pin TQFN (5mm x 5mm) MAX8855AETJ+ -40C to +85C 32 TQFN-EP* package with 0.8mm max height. +Denotes a lead(Pb)-free/RoHS-compliant package. Applications *EP = Exposed pad. ASIC/CPU/DSP Power Supplies Typical Operating Circuit DDR Power Supplies INPUT2 INPUT1 Set-Top Box Power Supplies 2.25V TO 3.6V 2.25V TO 3.6V Printer Power Supplies IN1 IN2 BST1 BST2 Network Power Supplies OUTPUT1 OUTPUT2 1.2V / 5A 1.5V / 5A LX1 LX2 PGND1 PGND2 MAX8855/ MAX8855A FB2 FB1 COMP1 COMP2 TYPE III TYPE III COMPENSATION COMPENSATION PWRGD1 PWRGD2 ON ON EN1 EN2 GND OFF OFF Pin Configuration appears at end of data sheet. Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com. EVALUATION KIT AVAILABLEDual, 5A, 2MHz Step-Down Regulators ABSOLUTE MAXIMUM RATINGS IN , LX , V , VDL, PWRGD to GND..................-0.3V to +4.5V Continuous Power Dissipation (T = +70C) DD A V , VDL to IN .....................................................-0.3V to +4.5V 32-Pin TQFN (5mm x 5mm) DD EN , SS , COMP , FB , REFIN, FSYNC to GND ......-0.3V to the (derate 34.5mW/C above +70C)..........................2758.6mW lower of (V + 0.3V) and (V + 0.3V) Operating Ambient Temperature Range .............-40C to +85C VDD VDL Continuous LX Current (Note 1) ...................................5.5A Operating Junction Temperature Range...........-40C to +125C RMS BST to LX ...........................................................-0.3V to +4.5V Storage Temperature Range .............................-65C to +150C PGND to GND......................................................-0.3V to +0.3V Lead Temperature (soldering, 10s) .................................+300C Soldering Temperature (reflow) .......................................+260C Note 1: LX have internal clamp diodes to PGND and IN . Applications that forward bias these diodes should take care not to exceed the ICs package power-dissipation limits. 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. PACKAGE THERMAL CHARACTERISTICS (Note 2) TQFN Junction-to-Ambient Thermal Resistance ( ) ...........29C/W JA Junction-to-Case Thermal Resistance ( ) ...............1.7C/W JC Note 2: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four- layer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial. ELECTRICAL CHARACTERISTICS (V = V = V = 3.3V, V = 0.5V, V = V = 600mV, PGND = GND, R = 10k, L = 0.47H, C = 0.1F, IN VDD VDL FB SS REFIN FSYNC BST C = 0.022F, PWRGD not connected T = -40C to +85C, typical values are at T = +25C, unless otherwise noted.) (Note 2) SS A A PARAMETER CONDITIONS MIN TYP MAX UNITS IN1, IN2, VDL, VDD MAX8855 2.35 3.60 IN , VDL, and V Voltage Range (Note 3) V DD MAX8855A 2.25 3.60 V = 2.5V 1.9 3.5 IN IN Supply Current 1MHz switching, no load mA V = 3.3V 2.8 5 IN V = 2.5V 7.2 VDD V + VDL Supply Current 1MHz switching, V = VDL mA DD DD V = 3.3V 10 15 VDD T = +25C 11 Shutdown Supply Current = V = V = V - A V IN VDD VDL B S T A (I + I + I + I ) V = 3.6V , V = 0V IN1 IN2 VDD VDL L X E N T = +85C 0.3 A Rising 2.0 2.2 IN , V Undervoltage Lockout Threshold DD V UVLO Monitors V , IN1, and IN2 DD Falling 1.8 1.9 IN , V Undervoltage Lockout Deglitch 2 s DD BST1, BST2 T = +25C 2 V = V = V = V = A IN VDD VDL BST Shutdown BST Current A 3.6V, V = 0V, V = 0 or 3.6V EN LX T = +85C 0.02 A COMP1, COMP2 COMP Clamp Voltage, High V = V = 2.25V to 3.6V, V = 0.7V 1.80 2.00 2.25 V VDD IN FB COMP Slew Rate 1.40 V/s COMP Shutdown Resistance From COMP to GND, V = 0V 7 25 EN 2 MAX8855/MAX8855A