MAX767 19-0224 Rev 3 7/00 5V-to-3.3V, Synchronous, Step-Down Power-Supply Controller General Description Features >90% Efficiency The MAX767 is a high-efficiency, synchronous buck controller IC dedicated to converting a fixed 5V supply 700A Quiescent Supply Current into a tightly regulated 3.3V output. Two key features set 120A Standby Supply Current this device apart from similar, low-voltage step-down 4.5V-to-5.5V Input Range switching regulators: high operating frequency and all N-channel construction in the application circuit. The Low-Cost Application Circuit 300kHz operating frequency results in very small, low- All N-Channel Switches cost external surface-mount components. Small External Components The inductor, at 3.3H for 5A, is physically at least five Tiny Shrink-Small-Outline Package (SSOP) times smaller than inductors found in competing solu- Predesigned Applications: tions. All N-channel construction and synchronous rectifi- Standard 5V to 3.3V DC-DC Converters up to 10A cation result in reduced cost and highest efficiency. High-Accuracy Pentium P54C VR-Spec Supply Efficiency exceeds 90% over a wide range of loading, Fixed Output Voltages Available: eliminating the need for heatsinking. Output capacitance 3.3V (Standard) requirements are low, reducing board space and cost. 3.45V (High-Speed Pentium) The MAX767 is a monolithic BiCMOS IC available in 3.6V (PowerPC) 20-pin SSOP packages. For other fixed output voltages Ordering Information and package options, please consult the factory. PIN- REF V OUT Applications PART TEMP. RANGE PACKAGE TOL (V) Local 5V-to-3.3V DC-DC Conversion MAX767CAP 0C to +70C 20 SSOP 1.8% 3.3 Microprocessor Daughterboards MAX767RCAP 0C to +70C 20 SSOP 1.8% 3.45 MAX767SCAP 0C to +70C 20 SSOP 1.8% 3.6 Power Supplies up to 10A or More MAX767TCAP 0C to +70C 20 SSOP 1.2% 3.3 MAX767C/D 0C to +70C Dice* Ordering Information continued at end of data sheet. Typical Application Circuit * Contact factory for dice specifications. INPUT Pin Configuration 4.5V TO 5.5V TOP VIEW V ON CC BST CS FB OUTPUT 1 20 DH 3.3V 3.3 H SS AT 5A 2 DH 19 ON LX 3 18 LX MAX767 GND 4 MAX767 BST 17 DL GND DL 5 16 PGND GND 6 15 V CC GND CS V 7 14 CC REF 8 13 PGND FB REF GND SYNC N.C. 9 12 V GND CC 10 11 SSOP Pentium is a trademark of Intel. PowerPC is a trademark of IBM. Maxim Integrated Products 1 For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com. EVALUATION KIT MANUAL FOLLOWS DATA SHEET5V-to-3.3V, Synchronous, Step-Down Power-Supply Controller ABSOLUTE MAXIMUM RATINGS V to GND.................................................................-0.3V, +7V REF Short to GND.......................................................Momentary CC PGND to GND ........................................................................2V REF Current.........................................................................20mA Continuous Power Dissipation (T = +70C) A BST to GND...............................................................-0.3V, +15V 20-Pin SSOP (derate 8.00mW/C above +70C) ..........640mW LX to BST.....................................................................-7V, +0.3V Operating Temperature Ranges: Inputs/Outputs to GND (ON, REF, SYNC, CS, FB, SS) .....................-0.3V, V + 0.3V MAX767CAP/MAX767 CAP.................................0C to +70C CC DL to PGND .....................................................-0.3V, V + 0.3V MAX767EAP/MAX767 EAP ..............................-40C to +85C CC DH to LX...........................................................-0.3V, BST + 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 (V = ON = 5V, GND = PGND = SYNC = 0V, I = 0mA, T = T to T , unless otherwise noted. Typical values are at T = +25C.) CC REF A MIN MAX A PARAMETER CONDITIONS MIN TYP MAX UNITS V Input Supply Range 4.5 5.5 V CC 0mV < (CS - FB) < 80mV, MAX767, MAX767T 3.17 3.35 3.46 4.5V < V < 5.5V CC Output Voltage (FB) MAX767R 3.32 3.50 3.60 V (includes load and line regulation) MAX767S 3.46 3.65 3.75 Load Regulation (CS - FB) = 0mV to 80mV 2.5 % Line Regulation V = 4.5V to 5.5V 0.1 % CC V Fault Lockout Voltage Falling edge, hysteresis = 1% 3.80 4.20 V CC Current-Limit Voltage CS - FB 80 100 120 mV SS Source Current 2.50 4 6.5 A SS Fault Sink Current 2 mA MAX767, MAX767R, MAX767S 3.24 3.30 3.36 Reference Voltage (REF) V MAX767T 3.26 3.30 3.34 V Standby Current ON = 0V, V = 5.5V 120 200 A CC CC V Quiescent Current FB = CS = 3.5V 0.7 1.0 mA CC SYNC = 3.3V 260 300 340 Oscillator Frequency kHz SYNC = 0V or 5V 200 Oscillator SYNC Range 240 350 kHz SYNC High Pulse Width 200 ns SYNC Low Pulse Width 200 ns SYNC Rise/Fall Time Not tested 200 ns SYNC = 3.3V 89 92 Oscillator Maximum Duty Cycle % SYNC = 0V 95 Input Low Voltage SYNC, ON 0.8 V ON 2.40 Input High Voltage V SYNC V - 0.5 CC Input Current SYNC, ON = 0V or 5V 1 A DL Sink/Source Current DL = 2V 1 A DH Sink/Source Current (BST - LX) = 4.5V, DH = 2V 1 A DL On Resistance High or low 7 DH On Resistance High or low, (BST - LX) = 4.5V 7 2 MAX767