MAX8744/MAX8745 19-3796 Rev 0 4/06 High-Efficiency, Quad-Output, Main Power- Supply Controllers for Notebook Computers General Description Features Fixed-Frequency, Current-Mode Control The MAX8744/MAX8745 are dual step-down, switch- mode, power-supply (SMPS) controllers with synchro- 40/60 Optimal Interleaving nous rectification, intended for main 5V/3.3V power Internal BST Switches generation in battery-powered systems. Fixed-frequen- Internal 5V, 100mA Linear Regulator cy operation with optimal interleaving minimizes input Auxiliary Linear-Regulator Driver (12V or ripple current from the lowest input voltages up to the Adjustable Down to 1V) 26V maximum input. Optimal 40/60 interleaving allows Dual Mode Feedback3.3V/5V Fixed or the input voltage to go down to 8.3V before duty-cycle Adjustable Output Voltages overlap occurs, compared to 180 out-of-phase regula- 200kHz/300kHz/500kHz Switching Frequency tors where the duty-cycle overlap occurs when the input drops below 10V. Undervoltage and Thermal-Fault Protection Overvoltage-Fault Protection (MAX8744 Only) Output current sensing provides peak current-limit pro- tection, using either an accurate sense resistor or using 6V to 26V Input Range lossless inductor DCR current sensing. A low-noise 2V 0.75% Reference Output mode maintains high light-load efficiency while keeping Independent Enable Inputs and Power-Good the switching frequency out of the audible range. Outputs An internal, fixed 5V, 100mA linear regulator powers up Soft-Start and Soft-Shutdown (Voltage Ramp) the MAX8744/MAX8745 and their gate drivers, as well 8A (typ) Shutdown Current as external keep-alive loads. When the main PWM reg- ulator is in regulation, an automatic bootstrap switch Ordering Information bypasses the internal linear regulator, providing current PIN- PKG up to 200mA. An additional adjustable linear-regulator PART TEMP RANGE PACKAGE CODE driver with an external pnp transistor may be used with 32 Thin QFN a secondary winding to provide a 12V supply, or pow- MAX8744ETJ+ -40C to +85C T3255-4 (5mm x 5mm) ered directly from the main outputs to generate low- voltage outputs as low as 1V. 32 Thin QFN MAX8745ETJ+ -40C to +85C T3255-4 (5mm x 5mm) Independent enable controls and power-good signals allow flexible power sequencing. Voltage soft-start +Denotes lead-free package. gradually ramps up the output voltage and reduces Pin Configuration inrush current, while soft-shutdown gradually ramps the output voltage down, preventing negative voltage dips. The MAX8744/MAX8745 feature output undervoltage TOP VIEW and thermal-fault protection. The MAX8744 also includes output overvoltage-fault protection. 24 23 22 21 20 19 18 17 The MAX8744/MAX8745 are available in a 32-pin, 5mm DH3 25 16 DH5 x 5mm, thin QFN package. The exposed backside pad improves thermal characteristics for demanding linear 15 BST5 BST3 26 keep-alive applications. 27 14 PGOOD5 PGOOD3 Applications 28 13 CSL5 CSL3 MAX8744 29 12 Main Power Supplies CSH3 CSH5 MAX8745 FB3 30 11 FB5 2 to 4 Li+ Cell Battery-Powered Devices FBA 31 10 SKIP Notebook and Subnotebook Computers + 32 9 OUTA FSEL PDAs and Mobile Communicators 12 3 45 6 7 8 Dual Mode is a trademark of Maxim Integrated Products, Inc. THIN QFN 5mm x 5mm 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 ONA LX3 DRVA DL3 ILIM PGOODA SHDN IN LDO5 ON3 ON5 PGND DL5 REF GND LX5High-Efficiency, Quad-Output, Main Power- Supply Controllers for Notebook Computers ABSOLUTE MAXIMUM RATINGS IN, SHDN, DRVA, OUTA to GND............................-0.3V to +28V BST3, BST5 LDO5.................................................-0.3V to +0.3V LDO Short Circuit to GND ..........................................Momentary LDO5, ON3, ON5, ONA to GND ..............................-0.3V to +6V PGOODA, PGOOD3, PGOOD5 to GND...................-0.3V to +6V REF Short Circuit to GND ...........................................Momentary DRVA Current (Sinking) ......................................................30mA CSL3, CSH3, CSL5, CSH5 to GND ..........................-0.3V to +6V OUTA Shunt Current ...........................................................30mA REF, FB3, FB5, FBA to GND...................-0.3V to (V + 0.3V) LDO5 SKIP, FSEL, ILIM to GND........................-0.3V to (V + 0.3V) Continuous Power Dissipation (T = +70C) LDO5 A Multilayer PCB DL3, DL5 to PGND..................................-0.3V to (V + 0.3V) LDO5 BST3, BST5 to PGND .............................................-0.3V to +34V 32-Pin, 5mm x 5mm TQFN (derated 34.5mW/C above +70C) .........................2459mW BST3 to LX3..............................................................-0.3V to +6V Operating Temperature Range ...........................-40C to +85C DH3 to LX3 ..............................................-0.3V to (V + 0.3V) BST3 BST5 to LX5..............................................................-0.3V to +6V Junction Temperature......................................................+150C Storage Temperature Range .............................-65C to +150C DH5 to LX5 ..............................................-0.3V to (V + 0.3V) BST5 GND to PGND .......................................................-0.3V to +0.3V Lead Temperature (soldering, 10s) ................................+300C 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, both SMPS enabled, FSEL = REF, SKIP = GND, ILIM = LDO5, FBA = LDO5, I = I = I = IN REF LDO5 OUTA no load, T = 0C to +85C, unless otherwise noted. Typical values are at T = +25C.) A A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS INPUT SUPPLIES (Note 1) LDO5 in regulation 5.4 26.0 V Input Voltage Range V V IN IN IN = LDO5, V < 4.4V 4.5 5.5 CSL5 LDO5 switched over to CSL5, either V Operating Supply Current I 20 36 A IN IN SMPS on V = 6V to 26V, both SMPS off, includes IN V Standby Supply Current I 65 120 A IN IN(STBY) I SHDN V Shutdown Supply Current I V = 6V to 26V 8 20 A IN IN(SHDN) IN Both SM P S on, FB3 = FB 5 = LDO5 , SKIP = GND , V = 3.5V, V = 5.3V, C S L 3 C S L 5 Quiescent Power Consumption P 3.5 4.5 mW Q V = 15V, OUT A P + P + P + P IN C S L 3 C S L 5 OUT A MAIN SMPS CONTROLLERS 3.3V Output Voltage in Fixed V = 6V to 26V, SKIP = FB3 = LDO5, IN V 3.265 3.315 3.365 V OUT3 Mode 0 < V - V < 50mV (Note 2) CSH3 CSL3 V = 6V to 26V, SKIP = FB5 = LDO5, IN 5V Output Voltage in Fixed Mode V 4.94 5.015 5.09 V OUT5 0 < V - V < 50mV (Note 2) CSH5 CSL5 V = 6V to 26V, FB3 or FB5 IN 1.980 2.010 2.040 duty factor = 20% to 80% Feedback Voltage in Adjustable V V FB Mode (Note 2) V = 6V to 26V, FB3 or FB5 IN 1.990 2.010 2.030 duty factor = 50% 2 MAX8744/MAX8745