MAX8537/MAX8538/MAX8539 19-3141 Rev 1 6/05 Dual-Synchronous Buck Controllers for Point-of- Load, Tracking, and DDR Memory Power Supplies General Description Features MAX8537/MAX8539: Complete DDR Supplies The MAX8537/MAX8539 controllers provide a complete power-management solution for both double-data-rate MAX8538: Dual Nontracking Controller (DDR) and combiner supplies. The MAX8537 and Out-of-Phase (MAX8537/MAX8538) or In-Phase MAX8539 are configured for out-of-phase and in-phase (MAX8539) Operation DDR power-supply operations, respectively, and gener- 4.5V to 23V Wide Input Range (Operate Down to ate three outputs: the main memory voltage (V ), the DDQ 1.8V Input with External 5V Supply) tracking sinking/sourcing termination voltage (V ), and TT Tracking Supply Maintains V = V = 1/2 V TT TTR DDQ the termination reference voltage (V ). The MAX8538 TTR Adjustable Output from 0.8V to 3.6V with 1% is configured as a dual out-of-phase controller for point- Accuracy of-load supplies. Each buck controller can source or sink up to 25A of current, while the termination refer- VTTR Reference Sources and Sinks Up to 15mA ence can supply up to 15mA output. 200kHz to 1.4MHz Adjustable Switching The MAX8537/MAX8538/MAX8539 use constant- Frequency frequency voltage-mode architecture with operating All-Ceramic Design Achievable frequencies of 200kHz to 1.4MHz. An internal high- >90% Efficiency bandwidth (25MHz) operational amplifier is used as an Independent POK and EN error amplifier to regulate the output voltage. This allows fast transient response, reducing the number of Adjustable Soft-Start and Soft-Stop for Each Output output capacitors. An all-N-FET design optimizes effi- ciency and cost. The MAX8537/MAX8538/MAX8539 Lossless Adjustable-Hiccup Current Limit have a 1% accurate reference. The second synchro- Output Overvoltage Protection nous buck controller in the MAX8537/MAX8539 and the 28-Pin QSOP Package VTTR amplifier generate 1/2 V voltage for V and DDQ TT V , and track the V within 1%. TTR DDQ This family of controllers uses a high-side current-sense architecture for current limiting. ILIM pins allow the set- Ordering Information ting of an adjustable, lossless current limit for different combinations of load current and R . Alternately, PIN- DSON PART TEMP RANGE OPERATION PACKAGE more accurate overcurrent limit is achieved by using a sense resistor in series with the high-side FET. Out-of-phase MAX8537EEI -40C to +85C 28 QSOP Overvoltage protection is achieved by latching off the tracking high-side MOSFET and latching on the low-side MOSFET Out-of-phase when the output voltage exceeds 17% of its set output. M AX85 37E E I+ -40C to +85C 28 QSOP tracking Independent enable, power-good, and soft-start features enhance flexibility. Out-of-phase MAX8538EEI -40C to +85C 28 QSOP nontracking Applications Out-of-phase M AX85 38E E I+ -40C to +85C 28 QSOP DDR Memory Power Supplies nontracking Notebooks and Desknotes In-phase MAX8539EEI -40C to +85C 28 QSOP Servers and Storage Systems tracking Broadband Routers In-phase M AX 8539E E I+ -40C to +85C 28 QSOP tracking XDSL Modems and Routers +Denotes lead-free package. Power DSP Core Supplies Power Combiner in Advanced VGA Cards Networking Systems RAMBUS Memory Power Supplies Pin Configurations appear at end of data sheet. 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 AVAILABLEDual-Synchronous Buck Controllers for Point-of- Load, Tracking, and DDR Memory Power Supplies ABSOLUTE MAXIMUM RATINGS V+ to GND..............................................................-0.3V to +25V LX to GND................................................................-2V to +25V AVL, VL to GND........................................................-0.3V to +6V DL to PGND ................................................-0.3V to (VL + 0.3V) PGND to GND .......................................................-0.3V to +0.3V Continuous Power Dissipation (T = +70C) A FB , EN , POK to GND...........................................-0.3V to +6V 28-Pin QSOP (derate 10.8mW/C above +70C)........860mW REFIN, VTTR, FREQ, SS , COMP to GND....-0.3V to (AVL + 0.3V) Operating Temperature Range ...........................-40C to +85C BST , ILIM to GND ...............................................-0.3V to +30V Junction Temperature......................................................+150C DH1 to LX1 ...............................................-0.3V to (BST1 + 0.3V) Storage Temperature Range .............................-65C to +150C DH2 to LX2 ...............................................-0.3V to (BST2 + 0.3V) Lead Temperature (soldering, 10s)..........................+300C 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, EN = VL, BST = 6V, LX = 1V, VL load = 0mA, C = 10F (ceramic), REFIN = 1.25V, PGND = AGND = FB = ILIM = VL 0V, C = 10nF, C = 1F, R = 20k , DH = open, DL = open, POK = open, circuit of Figure 1, T = 0C to +85C, unless SS VTTR FREQ A otherwise noted.) PARAMETER CONDITIONS MIN TYP MAX UNITS GENERAL V+ Operating Range VL regulator drops out below 5.5V (Note 1) 4.5 23.0 V V+/ VL Operating Range VL is externally generated (Note 1) 4.5 5.5 V V+ Operating Supply Current IL(VL) = 0, FB forced 50mV above threshold 3.5 7 mA V+ Standby Supply Current IL(VL) = 0, BST = VL, EN = LX = FB = 0V 350 700 A VL REGULATOR Output Voltage 5.5V < V+ < 23V, 1mA < I < 70mA 4.75 5 5.25 V LOAD VL Undervoltage-Lockout Trip Rising edge, hysteresis = 550mV (typ) (trip level is 4.18 4.3 4.42 V Level typically 85% of VL) This is for gate current of DL /DH drivers, C(VL) = Output Current 70 mA 1F/10mA ceramic capacitor Thermal Shutdown Rising temperature, typical hysteresis = 10C +160 C CURRENT-LIMIT THRESHOLD (all current limits are tested at V+ = VL = 4.5V and 5.5V) ILIM Sink Current ILIM = LX - 200mV, 1.8V < LX < 23V, BST = LX +5V 180 200 220 A SOFT-START Soft-Start Source Current SS = 100mV -7 -5 -3 A Soft-Start Sink Current SS = 0.8 or REFIN 3 5 7 A 0.8 or Soft-Start Full-Scale Voltage V REFIN FREQUENCY Low End of Range R = 100k , V+ = VL = 5V 160 200 240 kHz FREQ Intermediate Range R = 20k , V+ = VL = 5V 800 1000 1200 kHz FREQ High End of Range R = 14.3k , V+ = VL = 5V 1120 1400 1680 kHz FREQ R = 100k 95 FREQ Maximum Duty Cycle R = 20k 80 % FREQ R = 14.3k 72 FREQ 2 MAX8537/MAX8538/MAX8539