MAX1917 19-2335 Rev 1 6/02 Tracking, Sinking and Sourcing, Synchronous Buck Controller for DDR Memory and Termination Supplies General Description Features The MAX1917 provides a complete power-manage- 25A Sourcing and Sinking Current ment solution for DDR memory. It contains a synchro- Automatically Sets VTT to 1/2V DDR nous buck controller and an amplifier to generate 1/2V voltage for VTT and VTTR. The VTT and VTTR DDR VTT and VTTR Within 1% of 1/2V DDR voltages are maintained within 1% of 1/2V . The DDR Smallest Output Capacitors controller operates in synchronous rectification mode to ensure balanced current sourcing and sinking capabili- 4.5V to 14V (or 28V with Resistor-Divider) Input ty of up to 25A. With a shutdown current of less than Voltage Range 5A, the MAX1917 is the best choice for low-power 1.5V to 3.6V Input DDR Range notebook applications, as well as servers and desktop computers. An all N-FET design optimizes efficiency. 200kHz/300kHz/400kHz/550kHz Preset Switching The MAX1917 can also be used for generating V DDR Frequencies and as a general-purpose step-down controller with variable switching frequency as high as 1MHz with few Variable Switching Frequency of Up to 1MHz additional components. Overcurrent Protection Without Current-Sense The MAX1917 uses Maxims proprietary Quick-PWM Resistor architecture for fast transient response up to 96% effi- Internal Soft-Start ciency, and the smallest external components. Output current monitoring is achieved without sense resistors VTTR Reference Sources and Sinks Up to 25mA by monitoring the bottom FETs drain-to-source voltage. Quick-PWM Control for Fastest Loop Response The current-limit threshold is programmable through an external resistor. The MAX1917 comes in a space-sav- Up to 96% Efficiency ing 16-pin QSOP package. 16-Pin QSOP Package Applications DDR Memory Power Notebook Computers Ordering Information Supply Desktop Computers PART TEMP RANGE PIN-PACKAGE Processor or DSP Core Storage MAX1917EEE -40C to +85C 16 QSOP Supply Networking Systems AGTL Bus Termination Supply Typical Operating Circuit V (2.5V TO 15V) IN Quick-PWM is a trademark of Maxim Integrated Products, Inc. Pin Configuration EN/HSD DH POK POK VL TOP VIEW VDDR V OUT DDR BST MAX1917 EN/HSD 1 16 LX (4.5V TO 14V) V+ LX DDR 2 15 DH POK 3 14 BST REF DL VTT 4 MAX1917EEE 13 PGND ILIM PGND VL ILIM 5 12 DL FSEL VTT FSEL 6 11 VL VTTR REF 7 10 V+ GND VTTR GND 8 9 VTTR QSOP 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.Tracking, Sinking and Sourcing, Synchronous Buck Controller for DDR Memory and Termination Supplies ABSOLUTE MAXIMUM RATINGS V+ to GND..............................................................-0.3V to +15V REF Short Circuit to GND...........................................Continuous EN/HSD to GND .....................................................-0.3V to +16V Continuous Power Dissipation (T = +70C) A VL to GND ................................................................-0.3V to +6V 16-Pin QSOP (derate up to +70C)..............................667mW PGND to GND .......................................................-0.3V to +0.3V 16-Pin QSOP (derating above +70C).....................8.3mW/C VTT, DDR, POK to GND ...........................................-0.3V to +6V Operating Temperature Range REF, VTTR, DL, ILIM, FSEL to GND ................-0.3V to VL + 0.3V Extended .........................................................-40C to +85C LX to PGND ............................................................-0.3V to +30V Junction Temperature......................................................+150C BST to GND............................................................-0.3V to +36V Storage Temperature Range .............................-65C to +150C DH to LX ......................................................-0.3V to V + 0.3V Lead Temperature (soldering 10s.) .................................+300C BST LX to BST..................................................................-6V 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. ELECTRICAL CHARACTERISTICS (V+ = 12V, V = V = 2.5V, C = 4.7F, C = 1F, C = 0.22F, V = 0, ILIM = VL, PGND = LX = POK = GND, EN/HSD DDR VL VTTR REF FSEL BST = VL. Specifications are for T = 0C to +85C. Typical values are at T = +25C, unless otherwise specified.) A A PARAMETER CONDITIONS MIN TYP MAX UNITS 5.5 14.0 V+ Input Voltage Range V VL = V+ 4.5 5.5 EN/HSD Input Voltage Range Enabled 1.5 15.0 V DDR Input Voltage Range 0 3.6 V V+ Supply Current VTT = 2.0V 0.8 1.2 mA DDR Supply Current 115 250 A EN/HSD Supply Current 510 A VL Supply Current VL = V+ = 5.5V, VTT = 2.0V 0.8 1.2 mA V+ Shutdown Supply Current EN/HSD = 0V 3 5 A DDR Shutdown Supply Current EN/HSD = 0V 1 A VL Shutdown Supply Current VL = V+ = 5.5V 3 5 A VL Undervoltage Lockout Rising edge, hysteresis = 40mV 4.05 4.25 4.40 V Threshold VTT VTT Input Bias Current V = 2.5V -0.1 0 A VTT VTT Feedback Voltage Range 0 1.8 V Overload range, V = 1.8V 49.5 50 50.5 VTT Feedback Voltage DDR %V DDR Accuracy Overload range, V = 3.6V 49.5 50 50.5 DDR REFERENCE Reference Output Voltage V+ = VL = 4.5V to 5.5V, I = 0 1.98 2.00 2.02 V REF Reference Load Regulation V+ = VL = 5V, I = 0 to 50A 10 mV REF Reference UVLO V+ = VL = 5V 1.5 1.6 1.7 V VTTR VTTR Output Voltage Range 0 1.8 V I = -5mA to +5mA 49.5 50 50.5 VTTR VTTR Output Accuracy I = -25mA to +25mA, V = 1.8V 49 50 51 %V VTTR DDR DDR I = -25mA to +25mA, V = 3.6V 49.5 50 50.5 VTTR DDR 2 MAX1917