MAX8655 19-3982 Rev 2 10/10 Highly Integrated, 25A, Wide-Input, Internal MOSFET, Step-Down Regulator General Description Features The MAX8655 synchronous-PWM buck regulator oper- 25A Output Current ates from a 4.5V to 25V input and generates an output Integrated Power MOSFETs voltage adjustable from 0.7V to 5.5V at loads up to 25A. Operates from 4.5V to 25V Supply Integrated power MOSFETs provide a small footprint, ease of layout, and reduced EMI. Removing the board 1% FB Voltage Accuracy Over Temperature trace inductances ensures the highest efficiency at Adjustable Output Voltage Down to 0.7V high frequency. Adjustable Switching Frequency and External The MAX8655 uses peak current-mode control architec- Synchronization from 200kHz to 1MHz ture with an adjustable (200kHz to 1MHz), constant- switching frequency, which is externally synchronizable. 180 Phase-Shifted Synchronization The MAX8655s adjustable current limit uses the induc- Adjustable Overcurrent Limit tors DC resistance to improve efficiency or an external Adjustable Slope Compensation sense resistor for higher accuracy. Foldback type cur- rent limit is available to reduce the power dissipation Selectable Current-Limit Mode: Latch-Off or under severe-overload or short-circuit conditions. A ref- Automatic Recovery erence input is provided for use with a high-accuracy Monotonic Output Voltage Rise at Startup into external reference or for DDR and tracking applications. Prebias Output Monotonic startup provides safe starting into a prebi- Output Sources and Sinks Current for DDR ased output, where traditional step-down regulators Applications discharge the output capacitor during soft-start, creat- ing a negative voltage at the output and possibly dam- Enable Input aging the load. Power-OK (POK) Output A 180 out-of-phase synchronization output is available Adjustable Soft-Start for synchronizing with another MAX8655. Independently Adjustable Overvoltage Protection An enable input is provided for on/off control and to facilitate output sequencing. Output-voltage sensing for programmable overvoltage protection is provided and Typical Operating Circuit is independent of the feedback network to further enhance the output overvoltage protection. Overall, the MAX8655 provides enough flexibility for the experienced user, as well as simplicity and ease of use for non-power-supply engineers. Applications POWER-OK OUTPUT Point-of-Load Power Supplies CS- POK Telecom Power FSYNC INPUT FSYNC CS+ Networking PVIN Nonisolated DC-DC Power Modules IN MAX8655 SYNCO SYNC OUTPUT Servers and Workstations VL ON OFF ENABLE INPUT EN Notebook Computers VLGND IBA Power Supplies VL BST OUTPUT 0.7V TO 5.5V Ordering Information UP TO 25A LXB LX INPUT 7V TO 28V PVIN TEMP PART PIN-PACKAGE RANGE 56 TQFN- E P * AVL MAX8655ETN+ -40C to +85C ( 8mm x 8mm ) +Denotes a lead(Pb)-free/RoHS-compliant package. *EP = Exposed pad. 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 AVAILABLE REFIN SCOMP ILIM2 MODE SS COMP PGND AVL FB OVP GND ILIM1Highly Integrated, 25A, Wide-Input, Internal MOSFET, Step-Down Regulator ABSOLUTE MAXIMUM RATINGS PVIN, IN, EN to GND ..............................................-0.3V to +30V Operating Junction Temperature Range.......... -40C to +125C BST to LXB ............................................................-0.3V to +7.5V Junction Temperature......................................................+150C LX, LXB to GND............ (-2.5V for < 50ns transient) -1V to +30V (thermal resistance from JC ILIM2, ILIM1, SYNCO, FSYNC, OVP, junction to exposed pad) (Note 1) ...............................3.5C/W SCOMP to GND .....................................-0.3V to (V + 0.3V) (thermal resistance from junction to the top) ............3.9C/W AVL JT VL to PGND ...........................................................-0.3V to +7.5V I ..................................................................................27A LX(RMS) AVL, FB, POK, COMP, SS, MODE, REFIN to GND ..-0.3V to +6V Storage Temperature Range .............................-65C to +150C CS+, CS- to GND ....................................................-0.3V to +6V Lead Temperature (soldering, 10s) .................................+300C PGND to GND to VLGND ......................................-0.3V to +0.3V Soldering Temperature (reflow) .......................................+260C Note 1: 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. 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 = 12V, V - V = 6.5V, T = -40C to +85C, circuit of Figure 4, typical values are at T = +25C, unless otherwise noted.) (Note 2) IN BST LX A A PARAMETER CONDITIONS MIN TYP MAX UNITS PVIN Operating Voltage Range 3 25 V IN Operating Voltage Range VL = IN for V < 7V 4.5 25.0 V IN IN Quiescent Supply Current V = 0.75V, no switching 2 3 mA FB EN = GND, V 28V 10 IN Shutdown Supply Current A I + I + I , EN = GND, V = V = V = 5V 32 IN VL AVL AVL VL IN PVIN Shutdown Supply Current V = V = V 1 A PVIN LX BST AVL Undervoltage-Lockout V rising, 3% typical hysteresis 3.90 4.15 4.40 V AVL Threshold Minimum output voltage is limited by minimum duty cycle Output-Voltage Adjust Range 0.7 5.5 V and external components VL Regulation Voltage 7V < V < 28V 6.0 6.5 7.0 V IN AVL Regulation Voltage 5.5V < V < 7V, 1mA < I < 10mA 4.900 4.975 5.050 V VL LOAD AVL Output Current 10 mA SOFT-START SS Shutdown Resistance From SS to GND, V = 0V 20 100 EN SS Soft-Start Current V = 0.625V 18 23 28 A REF REFIN INPUT V - AVL REFIN Dual Mode Threshold V V AVL 1.0V REFIN Input Bias Current V = 0.7V to 1.5V -250 +250 nA REFIN REFIN Input Voltage Range 0 1.5 V Dual Mode is a trademark of Maxim Integrated Products, Inc. 2 MAX8655