MAX8720 19-3319 Rev 2 9/05 Dynamically Adjustable 6-Bit VID Step-Down Controller General Description Features The MAX8720 step-down controller is intended for core Quick-PWM Architecture CPU DC-DC converters in notebook computers. It fea- 1% V Accuracy Over Line and Load OUT tures a dynamically adjustable output, ultra-fast transient 6-Bit On-Board DAC with Input Muxes response, high DC accuracy, and the high efficiency needed for leading-edge CPU core power supplies. Precision-Adjustable V Slew Control OUT Maxims proprietary Quick-PWM quick-response, con- 0.275V to 1.850V Output Adjust Range stant-on-time, PWM control scheme handles wide Remote Feedback and Ground Sense input/output voltage ratios with ease and provides Supports Voltage-Positioned Applications 100ns instant-on response to load transients while maintaining a relatively constant switching frequency. 2V to 28V Battery Input Range The output voltage can be dynamically adjusted through 200kHz/300kHz/550kHz/1000kHz Switching the 6-bit digital-to-analog converter (DAC) over a 0.275V Frequency to 1.850V range in 25mV steps. The MAX8720 has inde- Over/Undervoltage Protection pendent four-level logic inputs for setting the suspend Drives Large Synchronous-Rectifier FETs voltage (S0-S1). Precision slew-rate control provides just-in-time arrival at the new DAC setting, minimizing 800A (typ) I Supply Current CC surge currents to and from the battery. The internal DAC 10A (typ) Shutdown Supply Current of the MAX8720 is synchronized to the slew-rate clock 2V 0.75% Reference Output for improved operation under aggressive power man- agement of newer chipsets and operating systems that PGOOD Blanking During Transition can make incomplete mode transitions. Remote feed- back and ground-sense inputs allow easy compensa- Ordering Information tion for IR drops in PC board traces. Single-stage buck conversion allows these devices to PART TEMP RANGE PIN-PACKAGE directly step down high-voltage batteries for the highest MAX8720EEI -40C to +85C 28 QSOP possible efficiency. Alternatively, two-stage conversion MAX8720ETX -40C to +85C 36 Thin QFN 6mm x 6mm (stepping down the 5V system supply instead of the battery) at a higher switching frequency allows the mini- mum possible physical size. Minimal Operating Circuit The MAX8720 is available in a 28-pin QSOP or 36-pin +5V BIAS 6mm x 6mm thin QFN package. V V CC DD Applications SHDN INPUT (V ) IN V+ 7V TO 28V CPU Core Supply Converters BST ILIM GPU Core Supply Converters DH AGND SKIP Notebook and Subnotebook Computers OUTPUT (V ) OUT LX SUS 0.275V TO 1.850V MAX8720 DL PGOOD PGND VID0 D0 VID1 D1 FB VID2 D2 FBS VID3 D3 GNDS D4 VID4 CC VID5 D5 Quick-PWM is a trademark of Maxim Integrated Products, Inc. REF S0 TIME Pin Configurations appear at end of data sheet. S1 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 AVAILABLEDynamically Adjustable 6-Bit VID Step-Down Controller ABSOLUTE MAXIMUM RATINGS (Note 1) V to AGND............................................................-0.3V to +6V DH to LX .....................................................-0.3V to (BST + 0.3V) CC V to PGND............................................................-0.3V to +6V DL to PGND................................................-0.3V to (V + 0.3V) DD DD AGND to PGND.....................................................-0.3V to +0.3V REF Short Circuit to AGND.........................................Continuous V+ to PGND............................................................-0.3V to +30V Continuous Power Dissipation (T = +70C) A SHDN to AGND ......................................................-0.3V to +16V 28-Pin QSOP (derate 10.8mW/C above +70C)........860mW D0D5, PGOOD, SUS, SKIP to AGND .....................-0.3V to +6V 36-Pin TQFN (derate 26.3mW/C above +70C) .....2105mW FB, FBS, GNDS to AGND...........................-0.3V to (V + 0.3V) Operating Temperature CC CC, ILIM, REF, TIME to AGND ...................-0.3V to (V + 0.3V) Extended Temperature Range .......................-40C to +85C CC S0, S1, TON to AGND ................................-0.3V to (V + 0.3V) Junction Temperature......................................................+150C CC BST to PGND..........................................................-0.3V to +36V Storage Temperature Range .............................-65C to +165C LX to BST..................................................................-6V to +0.3V Lead Temperature (soldering, 10s) .................................+300C Note 1: For the MAX8720EEI, AGND and PGND refer to a single pin designated GND. 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 (Circuit of Figure 1, V+ = 15V, SHDN = SKIP = V = V = +5V, V = 1.25V, T = 0C to +85C, unless otherwise noted. Typical DD CC OUT A values are at T = +25C.) A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS PWM CONTROLLER Battery voltage, V+ 2 28 Input Voltage Range V V , V 4.5 5.5 CC DD DAC codes from -1 +1 % 0.9V to 1.85V V+ = 4.5V to 28V, DAC codes from DC Output Voltage Accuracy includes load -10 +10 0.45V to 0.875V regulation error mV DAC codes from -18 +18 0.275V to 0.425V Line Regulation Error V = 4.5V to 5.5V, V+ = 4.5V to 28V 5 mV CC Remote-Sense Voltage Error FB to FBS or AGND to GNDS = 0 to 25mV 3 mV FBS Input Bias Current FB, FBS -0.2 +0.2 A GNDS Input Bias Current GNDS -1 +1 A FB Input Resistance 115 180 265 k 150kHz, R = 120k -8 +8 TIME TIME Frequency Accuracy 818kHz, R = 22k -12 +12 % TIME 38kHz, R = 470k -12 +12 TIME V+ = 5V, FB = 1.25V, TON = GND 230 260 290 (1000kHz) TON = REF 165 190 215 (550kHz) On-Time (Note 2) t ns ON V+ = 12V, TON = open 320 355 390 FB = 1.25V (300kHz) TON = V CC 465 515 565 (200kHz) 2 MAX8720