MAX8743EEI+TG51

19-3318; Rev 1; 8/05 Dual, High-Efficiency, Step-Down Controller with High Impedance in Shutdown The on-demand PWM controllers are free running, constant on-time with input feed-forward. This configuration provides ultra-fast transient response, wide input-output differential range, low supply current, and tight load-regulation characteristics. The MAX8743 is simple and easy to compensate. Single-stage buck conversion allows the MAX8743 to directly step down high-voltage batteries for the highest possible efficiency. Alternatively, two-stage conversion (stepping down the 5V system supply instead of the battery at a higher switching frequency) allows the minimum possible physical size. The MAX8743 is intended for generating chipset, DRAM, CPU I/O, or other low-voltage supplies down to 1V. The MAX8743 is available in 28-pin QSOP and 36-pin thin QFN packages. Features ♦ Ultra-High Efficiency ♦ Accurate Current-Limit Option ♦ Quick-PWM™ with 100ns Load-Step Response ♦ 1% VOUT Accuracy over Line and Load ♦ High Output Impedance in Shutdown ♦ Dual Mode™ Fixed 1.8V/1.5V/Adj or 2.5V/Adj Outputs ♦ Adjustable 1V to 5.5V Output Range ♦ 2V to 28V Battery Input Range ♦ 200kHz/300kHz/420kHz/540kHz Nominal Switching Frequency ♦ Adjustable Overvoltage Protection ♦ 1.7ms Digital Soft-Start ♦ Drives Large Synchronous-Rectifier FETs ♦ Power-Good Window Comparator ♦ 2V ±1% Reference Output Ordering Information TEMP RANGE PIN-PACKAGE MAX8743EEI PART -40°C to +85°C 28 QSOP MAX8743EEI+ -40°C to +85°C 28 QSOP +Denotes lead-free package. Ordering Information continued at end of data sheet. Minimal Operating Circuit Applications Notebook Computers 5V INPUT CPU Core Supplies Chipset/RAM Supplies as Low as 1V 1.8V and 2.5V I/O Supplies OUTPUT1 1.8V BATTERY 4.5V TO 28V VDD V+ VCC UVP ILIM1 ILIM2 ON1 ON2 OVP BST1 BST2 DH1 DH2 LX1 LX2 DL1 DL2 MAX8743EEI OUTPUT2 2.5V CS2 TON CS1 OUT1 PGOOD OUT2 REF SKIP Pin Configurations appear at end of data sheet. FB2 FB1 GND Quick-PWM and Dual Mode are trademarks of Maxim Integrated Products, Inc. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX8743 General Description The MAX8743 is a dual pulse-width modulation (PWM) controller configured for step-down (buck) topologies that provides the high efficiency, excellent transient response, and high DC output accuracy necessary for stepping down high-voltage batteries to generate lowvoltage chipset and RAM power supplies in notebook computers. The CS_ inputs can be used with low-side sense resistors to provide accurate current limits or can be connected to LX_, using low-side MOSFETs as current-sense elements. High output impedance in shutdown eliminates negative output voltages, saving the cost of a Schottky diode at the output. MAX8743 Dual, High-Efficiency, Step-Down Controller with High Impedance in Shutdown ABSOLUTE MAXIMUM RATINGS (Note 1) LX_ to BST_ ..............................................................-6V to +0.3V DH2 to LX2 ..............................................-0.3V to (VBST2 + 0.3V) REF Short Circuit to GND ...........................................Continuous Continuous Power Dissipation (TA = +70°C) 28-Pin QSOP (derate 10.8mW/°C above +70°C)........860mW 36-Pin 6mm ✕ 6mm Thin QFN (derate 26.3mW/°C above +70°C) .............................2105mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C V+ to AGND..............................................................-0.3 to +30V VCC to AGND............................................................-0.3V to +6V VDD to PGND............................................................-0.3V to +6V AGND to PGND .....................................................-0.3V to +0.3V PGOOD, OUT_ to AGND..........................................-0.3V to +6V OVP, UVP, ILIM_, FB_, REF, SKIP, TON, ON_ to AGND......................-0.3V to (VCC + 0.3V) DL_ to PGND ..............................................-0.3V to (VDD + 0.3V) BST_ to AGND........................................................-0.3V to +36V CS_ to AGND.............................................................-6V to +30V DH1 to LX1 ..............................................-0.3V to (VBST1 + 0.3V) Note 1: For the MAX8743EEI, 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, VDD = VCC = 5V, SKIP = AGND, V+ = 15V, TA = 0°C to +85°C, typical values are at +25°C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS PWM CONTROLLERS Input Voltage Range DC Output Voltage OUT1 (Note 2) DC Output Voltage OUT2 (Note 2) V+ VCC/VDD Battery voltage, V+ VCC, VDD V+ = 2V to 28V, ILOAD = 0 to 8A, SKIP = VCC, +25°C to +85°C VOUT1 V+ = 2V to 28V, ILOAD = 0 to 8A, SKIP = VCC, 0°C to +85°C V+ = 4.5V to 28V, ILOAD = 0 to 4A, SKIP = VCC, +25°C to +85°C VOUT2 V+ = 4.5V to 28V, ILOAD = 0 to 4A, SKIP = VCC, 0°C to +85°C 2 28 4.5 5.5 FB1 to AGND 1.782 1.8 1.818 1.515 FB1 to VCC 1.485 1.5 FB1 to OUT1 0.99 1 1.01 FB1 to AGND 1.773 1.8 1.827 FB1 to VCC 1.477 1.5 1.523 0.985 1 1.015 FB2 to AGND 2.475 2.5 2.525 FB2 to OUT2 0.99 1 1.01 FB2 to AGND 2.463 2.5 2.537 FB2 to OUT2 0.985 1 1.015 5.5 V 0.1 0.15 V VCC 0.4 V V OUT1, OUT2 Dual-Mode Threshold, Low OVP, FB_ 0.05 OVP, ILIM_ VCC 1.5 FB1 OUT_ Input Resistance FB_ Input-Bias Current Soft-Start Ramp Time 2 1 1.9 ROUT1 VOUT1 = 1.5V 75 ROUT2 VOUT2 = 2.5V 100 IFB 2.0 2.1 kΩ -0.1 Zero to full ILIM V FB1 to OUT1 Output Voltage Adjust Range Dual-Mode Threshold, High V +0.1 1700 _______________________________________________________________________________________ µA µs Dual, High-Efficiency, Step-Down Controller with High Impedance in Shutdown (Circuit of Figure 1, VDD = VCC = 5V, SKIP = AGND, V+ = 15V, TA = 0°C to +85°C, typical values are at +25°C, unless otherwise noted.) PARAMETER On-Time, Side 1 SYMBOL tON1 On-Time, Side 2 tON2 On-Time Tracking CONDITIONS V+ = 24V, VOUT1 = 2V (Note 3) MIN TYP MAX TON = AGND 120 137 153 TON = REF 153 174 195 TON = float 222 247 272 TON = VCC 316 353 390 TON = AGND 160 182 204 V+ = 24V, VOUT2 = 2V (Note 3) TON = REF 205 234 263 TON = float 301 336 371 TON = VCC 432 483 534 On-time 2 with respect to ontime 1 (Note 3) TON = AGND 125 135 145 TON = REF 125 135 145 TON = float 125 135 145 TON = VCC 125 135 145 UNITS ns ns % Minimum Off-Time tOFF (Note 3) 400 500 ns Quiescent Supply Current (VCC) ICC FB_ forced above the regulation point 1100 1500 µA Quiescent Supply Current (VDD) IDD FB_ forced above the regulation point