MAX1945R/MAX1945S 19-2640 Rev 1 7/04 1MHz, 1% Accurate, 6A Internal Switch Step-Down Regulators General Description Features The MAX1945R/MAX1945S high-efficiency pulse-width 6A PWM Step-Down Regulator with 95% modulation (PWM) switching regulators deliver up to 6A Efficiency of output current. The devices operate from an input 1MHz/500kHz Switching for Small External supply range of 2.6V to 5.5V and provide selectable output voltages of 1.8V, 2.5V, and adjustable output Components voltages from 0.8V to 85% of the supply voltage. With 2 0.76in Complete 6A Regulator Footprint V at 3.3V/5V, the input voltage can be as low as CC External Components Height <3mm 2.25V. The MAX1945R/MAX1945S are ideal for on- board post-regulation applications. Total output voltage 1% Output Accuracy over Load, Line, and error is less than 1% over load, line, and temperature. Temperature The MAX1945R/MAX1945S operate at a selectable Operate from 2.6V to 5.5V Supply fixed frequency (500kHz or 1MHz) or can be synchro- nized to an external clock (400kHz to 1.2MHz). The Operate from 2.5V Input with V at 3.3V/5V CC high operating frequency minimizes the size of external Preset Output Voltage of 1.8V or 2.5V components. The high bandwidth of the internal error amplifier provides excellent transient response. The Adjustable Output from 0.8V to 85% of Input MAX1945R/MAX1945S have internal dual N-channel Voltage Margining: 4% (MAX1945R) or 9% MOSFETs to lower heat dissipation at heavy loads. Two (MAX1945S) MAX1945R/MAX1945Ss can operate 180 degrees out- of-phase of each other to minimize input capacitance. Synchronize to External Clock The devices provide output voltage margining for SYNCOUT Provides 180-Degree Out-of-Phase board-level testing. The MAX1945R provides a 4% voltage margining. The MAX1945S provides a 9% Clock Output voltage margining. All-Ceramic or Electrolytic Capacitor Designs The MAX1945R/MAX1945S are available in 28-pin Ordering Information TSSOP-EP packages and are specified over the -40C to +85C industrial temperature range. An evaluation kit PART TEMP RANGE PIN-PACKAGE is available to speed designs. MAX1945REUI -40C to +85C 28 TSSOP-EP* MAX1945SEUI -40C to +85C 28 TSSOP-EP* *EP = Exposed pad. Applications Low-Voltage, High-Density Distributed Power Typical Operating Circuit Supplies ASIC, CPU, and DSP Core Voltages RAM Power Supply BST OUTPUT Base Station, Telecom, and Networking INPUT LX IN 0.8V TO 2.6V TO 5.5V 0.85 x V , IN Equipment Power Supplies V DD 6A Server and Notebook Power Supplies V CC MAX1945R MAX1945S CTL1 VOLTAGE PGND MARGINING CTL2 ON/OFF SYNC FB SYNCHRONIZATION SYNCOUT COMP CLOCK 180 OUT-OF-PHASE Pin Configuration appears at end of data sheet. FBSEL REF GND Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com. EVALUATION KIT AVAILABLE1MHz, 1% Accurate, 6A Internal Switch Step-Down Regulators ABSOLUTE MAXIMUM RATINGS CTL1, CTL2, IN, SYNC, V , V to GND...............-0.3V to +6V Continuous Power Dissipation (T = +85C) CC DD A SYNCOUT, COMP, FB, FBSEL, (derate 23.8mW/C above +70C).............................1191mW REF to GND............................................-0.3V to (V + 0.3V) Operating Temperature Range ...........................-40C to +85C CC LX Current (Note 1).....................................................-9A to +9A Storage Temperature Range .............................-65C to +150C BST to LX..................................................................-0.3V to +6V Lead Temperature (soldering, 10s) .................................+300C PGND to GND .......................................................-0.3V to +0.3V 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. 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. ELECTRICAL CHARACTERISTICS (V = V = V = V = V = 3.3V, SYNC = GND, FBSEL = High-Z, V = 0.7V, C = 0.22F, T = 0C to +85C, unless IN CC CTL1 CTL2 DD FB REF A otherwise noted. Typical values are at +25C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS IN/V CC Input Voltage V 2.6 5.5 V IN V = 3.3V 12 20 SYNC = V (1MHz), IN CC IN Supply Current I mA IN no load V = 5.5V 48 IN V = 3.3V 2 3 CC V Supply Current I SYNC = V (1MHz) mA CC CC CC V = 5.5V 3 CC V = 3.3V 5 8 DD V Supply Current I SYNC = V (1MHz) mA DD DD CC V = 5.5V 10 DD Total Shutdown Current from IN, V = V = V = V - V = 5.5V, IN CC DD BST LX I 500 A TOTAL V , and V CTL1 = CTL2 = GND CC DD V rising 2.40 2.55 V Undervoltage Lockout When LX starts/stops CC CC V V UVLO Threshold switching V falling 2.20 2.35 CC V DD V = V = V = 5.5V, V = 5.5V or 0, IN DD BST LX V Shutdown Supply Current 10 A DD CTL1 = CTL2 = GND BST V = V = V = 5.5V, V = 5.5V or 0, IN DD BST LX BST Shutdown Supply Current I 10 A BST CTL1 = CTL2 = GND REF REF Voltage V I = 0, V = 2.6V to 5.5V 1.97 2.00 2.04 V REF REF IN REF Shutdown Resistance From REF to GND, CTL1 = CTL2 = GND 10 100 COMP FBSEL = High-Z 30 55 85 From FB to COMP, COMP Transconductance FBSEL = GND 13.3 24.4 37.8 S V = 1.25V COMP FBSEL = V 9.6 17.6 27.2 CC V LOW COMP Clamp Voltage Low V = 2.6V to 5.5V, V = 0.9V 0.5 0.8 1.1 V IN FB CLAMP V HIGH COMP Clamp Voltage High V = 2.6V to 5.5V, V = 0.7V 1.90 2.15 2.40 V IN FB CLAMP COMP Shutdown Resistance From COMP to GND, CTL1 = CTL2 = GND 10 100 2 MAX1945R/MAX1945S