MAX8529 19-2696 Rev 1 4/07 1.5MHz Dual 180 Out-of-Phase PWM Step-Down Controller with POR General Description Features The MAX8529 dual, synchronized, step-down controller Low Output Noise in DSL Band generates two outputs from input supplies ranging from Ceramic Input/Output Capacitors 4.75V to 23V. Each output is adjustable from sub-1V to 18V. Input voltage ripple and total RMS input ripple Step-Down or Step-Up/Step-Down Operation current are reduced by synchronized 180-degree out-of- Four Output, 90-Degree Out-of-Phase Operation phase operation. (Using Two MAX8529s) The switching frequency is adjustable from 600kHz to 1.5MHz with an external resistor. Alternatively, the con- Foldback Current Limit troller can be synchronized to an external clock gener- 4.75V to 23V Input Supply Range ated to another MAX8529 or a system clock. One MAX8529 can be set to generate an in-phase, or 90- 0 to 18V Output Voltage Range (Up to 6A) degree out-of-phase, clock signal for synchronization > 90% Efficiency with additional controllers. This allows two controllers to operate either as an interleaved two- or four-phase sys- Fixed-Frequency PWM Operation tem with each output shifted by 90 degrees. These Adjustable 600kHz to 1.5MHz Switching devices also feature soft-start and soft-stop. Frequency The MAX8529 eliminates the need for current-sense External SYNC Input resistors by utilizing the low-side MOSFETs on-resis- tance as a current-sense element. This protects the Clock Output for Master/Slave Synchronization DC-to-DC components from damage during output overload conditions or when output short circuit faults Soft-Start and Soft-Stop without requiring a current-sense resistor. Adjustable RST Output with 140ms Minimum Delay foldback current limit reduces power dissipation during short-circuit conditions. The MAX8529 includes a Lossless Current Limit (No Sense Resistor) power-on reset output to signal the system when both Ordering Information outputs reach regulation. PART TEMP RANGE PIN-PACKAGE The MAX8529 is available in a 24-pin QSOP package. An evaluation kit is available to speed designs. MAX8529EEG -40C to +85C 24 QSOP Pin Configuration Applications xDSL Modems and Routers TOP VIEW DSP, ASIC, and FPGA Power Supplies COMP2 1 24 EN Set-Top Boxes FB2 2 23 DH2 Broadband Routers ILIM2 3 22 LX2 OSC 4 21 BST2 V+ 5 20 DL2 REF 6 MAX8529 19 V L GND 7 18 PGND CKO 8 17 DL1 SYNC 9 16 BST1 ILIM1 10 15 LX1 FB1 11 14 DH1 COMP1 12 13 RST QSOP 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 AVAILABLE1.5MHz Dual 180 Out-of-Phase PWM Step-Down Controller with POR ABSOLUTE MAXIMUM RATINGS V+ to GND..............................................................-0.3V to +25V FB1, FB2, RST, SYNC, EN to GND...........................-0.3V to +6V PGND to GND .......................................................-0.3V to +0.3V V to GND Short Circuit..............................................Continuous L V to GND ..................-0.3V to the lower of +6V and (V+ + 0.3V) REF to GND Short Circuit...........................................Continuous L BST1, BST2 to GND ...............................................-0.3V to +30V Continuous Power Dissipation (T = +70C) A LX1 to BST1..............................................................-6V to +0.3V 24-Pin QSOP (derate 9.4mW/C above +70C)...........762mW LX2 to BST2..............................................................-6V to +0.3V Operating Temperature Range ...........................-40C to +85C DH1 to LX1 ..............................................-0.3V to (V + 0.3V) BST1 Junction Temperature......................................................+150C DH2 to LX2 ..............................................-0.3V to (V + 0.3V) Storage Temperature Range .............................-65C to +150C BST2 DL1, DL2 to PGND........................................-0.3V to (V + 0.3V) Lead Temperature (soldering, 10s) .................................+300C L CKO, REF, OSC, ILIM1, ILIM2, COMP1, COMP2 to GND ..........................-0.3V to (V + 0.3V) L 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 = ILIM = V , SYNC = GND, I = 0mA, PGND = GND, C = 0.22F, C = 4.7F (ceramic), R = 10k, L VL REF VL OSC compensation components for COMP are from Figure 1, T = -40C to +85C (Note 1), unless otherwise noted.) A PARAMETER CONDITIONS MIN TYP MAX UNITS GENERAL (Note 2) 4.75 23.00 V+ Operating Range V V = V+ (Note 2) 4.75 5.50 L V+ Operating Supply Current V unloaded, no MOSFETs connected 4.0 4.8 7.0 mA L V+ Standby Supply Current EN = LX = FB = 0V R = 10k 0.50 0.65 1.00 mA OSC Thermal Shutdown Rising temperature, typical hysteresis = 10C 160 C ILIM = V 75 100 125 L Current-Limit Threshold PGND - LX mV R = 100k 32 50 62 ILIM R = 600k 225 300 375 ILIM V REGULATOR L Output Voltage 5.5V < V+ < 23V, 1mA < I < 50mA 4.75 5 5.25 V LOAD V Undervoltage Lockout L 4.4 4.55 4.7 V Trip Level REFERENCE Output Voltage I = 0A 1.98 2.00 2.02 V REF Reference Load Regulation 0A < I < 50A 0 4 10 mV REF SOFT-START DC-to- Internal 6-bit DAC for one converter to ramp from 0V to Digital Ramp Period 1024 DC full scale (Note 3) Clocks Soft-Start Steps 64 Steps FREQUENCY Low End of Range R = 10k 540 600 600 kHz OSC High End of Range R = 5k 1020 1200 1380 kHz OSC DH Minimum Off-Time R = 5k 110 160 ns OSC 2 MAX8529