MAX8792 19-0739 Rev 1 2/10 Single Quick-PWM Step-Down Controller with Dynamic REFIN General Description Features Quick-PWM with Fast Transient Response The MAX8792 pulse-width modulation (PWM) controller provides high efficiency, excellent transient response, Supports Any Output Capacitor and high DC-output accuracy needed for stepping No Compensation Required with down high-voltage batteries to generate low-voltage Polymers/Tantalum Stable with Ceramic Output Capacitors Using core or chipset/RAM bias supplies in notebook comput- External Compensation ers. The output voltage can be dynamically controlled using the dynamic REFIN, which supports input volt- Precision 2V 10mV Reference ages between 0 to 2V. The REFIN adjustability com- Dynamically Adjustable Output Voltage bined with a resistive voltage-divider on the feedback (0 to 0.9V Range) IN input allows the MAX8792 to be configured for any out- Feedback Input Regulates to 0 to 2V REFIN put voltage between 0 to 0.9V . IN Voltage 0.5% V Accuracy Over Line and Load OUT Maxims proprietary Quick-PWM quick-response, con- stant-on-time PWM control scheme handles wide 26V Maximum Input Voltage Rating input/output voltage ratios (low-duty-cycle applications) Adjustable Valley Current-Limit Protection with ease and provides 100ns instant-on response to Thermal Compensation with NTC load transients while maintaining a relatively constant Supports Foldback Current Limit switching frequency. Strong drivers allow the MAX8792 Resistively Programmable Switching Frequency to efficiently drive large synchronous-rectifier MOSFETs. Overvoltage Protection The controller senses the current across the synchro- Undervoltage/Thermal Protection nous rectifier to achieve a low-cost and highly efficient Voltage Soft-Start and Soft-Shutdown valley current-limit protection. The adjustable current- limit threshold provides a high degree of flexibility, Monotonic Power-Up with Precharged Output allowing thermally compensated protection using an Power-Good Window Comparator NTC or foldback current-limit protection using a volt- age-divider derived from the output. Ordering Information The MAX8792 includes a voltage-controlled soft-start PKG TOP and soft-shutdown in order to limit the input surge cur- PART PIN-PACKAGE CODE MARK rent, provide a monotonic power-up (even into a MAX8792ETD+T 14 TDFN - E P * 3mm x 3mm T1433-1 ADC precharged output), and provide a predictable power- up time. The controller also includes output fault protec- Note: This device is specified over the -40C to +85C operating temperature range. tionundervoltage and overvoltage protectionas well as thermal-fault protection. +Denotes a lead(Pb)-free/RoHS-compliant package. The MAX8792 is available in a tiny 14-pin, 3mm x 3mm Pin Configuration TDFN package. For space-constrained applications, refer to the MAX17016 single step-down with 10A, 26V internal MOSFETs available in a small 40-pin, 6mm x TOP VIEW 6mm TQFN package. 14 13 12 11 10 9 8 . Applications Notebook Computers I/O and Chipset Supplies GPU Core Supply MAX8792 DDR MemoryVDDQ or VTT Point-of-Load Applications GND Step-Down Power Supply 1243 5 6 7 TDFN (3mm x 3mm) Quick-PWM is a trademark of Maxim Integrated Products, Inc. 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 EN PGOOD V V DD CC DL SKIP LX REF DH REFIN BST ILIM TON FBSingle Quick-PWM Step-Down Controller with Dynamic REFIN ABSOLUTE MAXIMUM RATINGS TON to GND ...........................................................-0.3V to +28V DH to LX....................................................-0.3V to (V + 0.3V) BST V to GND..............................................................-0.3V to +6V REF Short Circuit to GND...........................................Continuous DD V to GND................................................-0.3V to (V + 0.3V) Continuous Power Dissipation (T = +70C) CC DD A EN, SKIP, PGOOD to GND.......................................-0.3V to +6V 14-Pin 3mm x 3mm TDFN REF, REFIN to GND....................................-0.3V to (V + 0.3V) (derated 24.4mW/C above +70C)....................1951mW CC ILIM, FB to GND .........................................-0.3V to (V + 0.3V) Operating Temperature Range (extended).........-40C to +85C CC DL to GND..................................................-0.3V to (V + 0.3V) Junction Temperature......................................................+150C DD BST to GND.................................................(V - 0.3V) to +34V Storage Temperature.........................................-65C to +150C DD BST to LX..................................................................-0.3V to +6V Lead Temperature (soldering, 10s) .................................+300C BST to V .............................................................-0.3V to +28V Soldering Temperature (reflow) .......................................+240C DD 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 = 12V, V = V = V = 5V, REFIN = ILIM = REF, SKIP = GND. T = 0C to +85C, unless otherwise spec- IN DD CC EN A ified. Typical values are at T = +25C.) (Note 1) A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS PWM CONTROLLER Input Voltage Range V 226V IN Quiescent Supply Current (V )I + I FB forced above REFIN 0.7 1.2 mA DD DD CC Shutdown Supply Current (V)I EN = GND, T = +25C 0.1 2 A DD SHDN A V -to-V Resistance R 20 DD CC CC R = 97.5k (600kHz) 118 139 160 TON V = 12V, IN On-Time t V = 1.0V R = 200k (300kHz) 250 278 306 ns ON FB TON (Note 3) R = 302.5k (200kHz) 354 417 480 TON Minimum Off-Time t (Note 3) 200 300 ns OFF(MIN) EN = GND, V = 26V, TON TON Shutdown Supply Current 0.01 1 A V = 0V or 5V, T = +25C CC A REFIN Voltage Range V (Note 2) 0 V V REFIN REF FB Voltage Range V (Note 2) 0 V V FB REF T = +25C 0.495 0.5 0.505 V = 0.5V, REFIN A m easured at FB, V = 2V to 26 V , I N T = 0C to +85C 0.493 0.507 A SKIP = V DD FB Voltage Accuracy V V FB T = +25C 0.995 1.0 1.005 A V = 1.0V REFIN T = 0C to +85C 0.993 1.007 A V = 2.0V T = 0C to +85C 1.990 2.0 2.010 REFIN A FB Input Bias Current I V = 0.5V to 2.0V, T = +25C -0.1 +0.1 A FB FB A Load-Regulation Error I = 0 to 3A, SKIP = V 0.1 % LOAD DD Line-Regulation Error V = 4.5V to 5.5V, V = 4.5V to 26V 0.25 % CC IN Soft-Start/-Stop Slew Rate t Rising/falling edge on EN 1 mV/s SS Dynamic REFIN Slew Rate t Rising edge on REFIN 8 mV/s DYN REFERENCE No load 1.990 2.00 2.010 V = 4.5V CC Reference Voltage V V REF to 5.5V I = -10A to +50A 1.98 2.02 REF 2 MAX8792