MAX8654 19-0588 Rev 3 6/11 12V, 8A 1.2MHz Step-Down Regulator General Description Features The MAX8654 high-efficiency switching regulator delivers Internal 26m R MOSFETs DS(ON) up to 8A of load current at output voltages from 0.6V to Guaranteed 8A Output Current 0.85 x V . The IC operates from 4.5V to 14V, making it IN Adjustable Overcurrent Protection ideal for on-board point-of-load and postregulation appli- 1% Output Accuracy Over Temperature cations, with total output error less than 1% over load, Operates from 4.5V to 14V Supply line, and temperature ranges. Adjustable Output from 0.6V to 0.85 x V IN The MAX8654 is a fixed-frequency PWM mode regulator Soft-Start Reduces Inrush Supply Current with a switching frequency range of 250kHz to 1.2MHz 250kHz to 1.2MHz Adjustable Switching or SYNC set by an external resistor or SYNC input. High-frequency Input operation allows for an all-ceramic-capacitor solution. A SYNCOUT output is provided to synchronize a second Compatible with Ceramic, Polymer, and regulator switching 180 out-of-phase with the first to Electrolytic Output Capacitors reduce the input ripple current and consequently reduce SYNCOUT Synchronizes 2nd Regulator 180 the required input capacitance. The high operating fre- Out-of-Phase quency minimizes the size of external components. 36-Pin, Lead-Free, 6mm x 6mm TQFN Package The on-board low R dual-nMOS design keeps DS(ON) the board cooler at heavy loads while minimizing the critical inductances, making the layout a much simpler Ordering Information task with respect to the discrete solutions. PIN- PART TEMP RANGE The MAX8654 comes with a high-bandwidth (20MHz) PACKAGE voltage-error amplifier. The voltage-mode control archi- MAX8654ETX+ -40C to +85C 36 TQFN-EP* tecture and the op-amp voltage-error amplifier permit a type 3 compensation scheme to be utilized to achieve +Denotes a lead(Pb)-free/RoHS-compliant package. maximum loop bandwidth, up to 20% of the switching *EP = Exposed pad. frequency. High loop bandwidth achieves fast transient response resulting in less output capacitance required. The MAX8654 offers programmable soft-start to accom- Typical Operating Circuit modate different types of output capacitors and reduce input inrush current. The MAX8654 is available in a 36- INPUT lead TQFN package. 4.5V TO 14V IN BST OUTPUT Applications VP UP TO 8A LX POL Power Supplies VL Servers VL PGND DDR Memory VDL RAID Power Supplies MAX8654 FB Network Power Supplies FREQ Graphic Cards ILIM COMP REFIN SS SYNC VL SYNCOUT IN PWRGD EN GND 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 AVAILABLE12V, 8A 1.2MHz Step-Down Regulator ABSOLUTE MAXIMUM RATINGS SYNC, VL, PWRGD to GND...................................-0.3V to +4.5V PGND to GND .......................................................-0.3V to +0.3V SYNCOUT, COMP, SS, FB, Continuous Power Dissipation (T = +70C) A REFIN, ILIM, FREQ to GND.....................-0.3V to (V + 0.3V) 36-Pin TQFN (derate 35.7mW/C above +70C) .........2857.1mW VL VDL to PGND............................................................-0.3V to +6V Operating Temperature Range ...........................-40C to +85C VP, IN, EN to GND..................................................-0.3V to +16V Junction Temperature .......+150C LX Current (Note 1: -12A to +12A) Storage Temperature Range .............................-65C to +150C BST to LX.-0.3V to +6V Thermal Resistance Junction to Exposed Pad (EP)...........3C/W BST to GND..-0.3V to (V + 6V) Lead Temperature (soldering, 10s) .................................+300C IN EN to VP and IN-0.3V to (V + 0.3V) Soldering Temperature (reflow) .......................................+260C IN Note 1: LX has 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. ELECTRICAL CHARACTERISTICS (V = V = V = 12V, V = 5V, V = 3.3V, V = 0V, V = 0.5V, T = -40C to +85C, typical values are at T = +25C, IN EN VP VDL VL SYNC FB A A unless otherwise noted.) PARAMETER CONDITIONS MIN TYP MAX UNITS IN/VP IN and VP Voltage Range 4.5 14 V VDL Voltage Range VP = VDL 4.5 5.5 V VL Output Voltage I = 5mA 3.3 V VL VDL Output Voltage I = 50mA 5 V VDL Not switching, no load 2.7 IN + VP Supply Current V = 12V 45 mA f = 500kHz, no load, IN S L = 1.5H V = 4.5V 28 IN VL Supply Current f = 500kHz, V = 3.8V from separate supply 1.6 mA S VL VDL Supply Current f = 500kHz, V = 5.5V from separate supply 25 mA S VDL IN + VP Shutdown Current V = V = 13.2V, V = V = V = unconnected 10 20 A P IN EN VDL VL V rising 3 3.1 VL VL Undervoltage Lockout LX starts/stops switching, V Threshold 2s rising/falling edge deglitch V falling 2.8 2.9 VL V rising 4.4 VDL and IN Undervoltage LX starts/stops switching, IN V Lockout Threshold 3s rising/falling edge deglitch V falling 3.8 IN BST BST Shutdown Supply Current V = 0V, V = V = V = V = 5V 10 A EN IN VP BST VDL PWM COMPARATOR PWM Comparator Propagation 5mV overdrive 16 ns Delay COMP COMP Clamp Voltage, High 1.8 V COMP Slew Rate 7 V/s COMP Shutdown Resistance From COMP to GND, V = 0V 7 EN 2 MAX8654