MAX748A/MAX763A 19-0190 Rev 0 9/93 3.3V, Step-Down, Current-Mode PWM DC-DC Converters General Description Features The MAX748A/MAX763A are 3.3V-output CMOS, step- Up to 500mA Load Currents down switching regulators. The MAX748A accepts Guaranteed 159kHz to 219.5kHz Current-Mode inputs from 3.3V to 16V and delivers up to 500mA. The PWM MAX763A accepts inputs between 3.3V and 11V and 85% to 90% Efficiencies delivers up to 500mA. Typical efficiencies are 85% to 90%. Quiescent supply current is 1.4mA (MAX763A), 1.7mA Quiescent Current (MAX748A) and only 0.2A in shutdown. 1.4mA Quiescent Current (MAX763A) Pulse-width-modulation (PWM) current-mode control pro- 0.2A Shutdown Supply Current vides precise output regulation and excellent transient 22H Preselected Inductor Value responses. Output voltage accuracy is guaranteed to be No Component Design Required 5% over line, load, and temperature variations. Fixed-frequency switching allows easy filtering of output Overcurrent, Soft-Start, and Undervoltage ripple and noise, as well as the use of small external Lockout Protection components. A 22H inductor works in most applica- Cycle-by-Cycle Current Limiting tions, so no magnetics design is necessary. 8-Pin DIP/SO Packages (MAX763A) The MAX748A/MAX763A also feature cycle-by-cycle cur- rent limiting, overcurrent limiting, undervoltage lockout, Ordering Information and programmable soft-start protection. The MAX748A is available in 8-pin DIP and 16-pin wide SO packages PART TEMP. RANGE PIN-PACKAGE the MAX763A comes in 8-pin DIP and SO packages. MAX748ACPA 0C to +70C 8 Plastic DIP MAX748ACWE 0C to +70C 16 Wide SO Applications MAX748AC/D 0C to +70C Dice* 5V-to-3.3V Converters MAX748AEPA -40C to +85C 8 Plastic DIP Cellular Phones MAX748AEWE -40C to +85C 16 Wide SO Portable Instruments MAX748AMJA -55C to +125C 8 CERDIP Hand-Held Computers Ordering Information continued on last page. Computer Peripherals * Contact factory for dice specifications. Typical Operating Circuit Pin Configurations INPUT TOP VIEW 3.3V TO 16V OUTPUT 22H V+ 3.3V LX MAX748A SHDN 1 8 V+ REF LX 2 7 ON/OFF SHDN OUT MAX748A SS 3 6 GND MAX763A 100F CC 4 OUT 5 REF CC SS GND DIP Pin Configurations continued on last page. Maxim Integrated Products 1 Call toll free 1-800-998-8800 for free samples or literature.3.3V, Step-Down, Current-Mode PWM DC-DC Converters ABSOLUTE MAXIMUM RATINGS Pin Voltages: 16-Pin Wide SO (derate 9.52mW/C above +70C)....762mW V+ (MAX748A)......................................................+17V, -0.3V 8-Pin CERDIP (derate 8.00mW/C above +70C) .......640mW V+ (MAX763A)......................................................+12V, -0.3V Operating Temperature Ranges: LX (MAX748A) .................................(V+ - 21V) to (V+ + 0.3V) MAX7 AC ....................................................0C to +70C LX (MAX763A) .................................(V+ - 12V) to (V+ + 0.3V) MAX7 AE .................................................-40C to +85C OUT.................................................................................25V MAX7 AMJA ..........................................-55C to +125C SS, CC, SHDN ..........................................-0.3V to (V+ + 0.3V) Junction Temperatures: Peak Switch Current (I ) .....................................................2.0A MAX7 AC/E ..............................................................+150C LX Reference Current (I ) ...................................................2.5mA MAX7 AM .................................................................+175C REF Continuous Power Dissipation (T = +70C) Storage Temperature Range ............................-65C to +160C A 8-Pin Plastic DIP (derate 6.90mW/C above +70C)...552mW Lead Temperature (soldering, 10sec) ............................+300C 8-Pin SO (derate 5.88mW/C above +70C) ...............471mW 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 3, V+ = 5V, I = 0mA, T = T to T , unless otherwise noted.) LOAD A MIN MAX MAX748A MAX763A PARAMETER CONDITIONS UNITS MIN TYP MAX MIN TYP MAX Input Voltage Range 3.3 16.0 3.3 11.0 V C/E temp. ranges, V+ = 4.0V to 16V, 3.135 3.3 3.465 0mA < I < 300mA LOAD M temp. range, V+ = 4.0V to 16V, 3.135 3.3 3.465 0mA < I < 250mA LOAD C/E temp. ranges, V+ = 4.75V to 16V, 3.135 3.3 3.465 0mA < I < 500mA LOAD M temp. range, V+ = 4.75V to 16V, 3.135 3.3 3.465 0mA < I < 400mA LOAD Output Voltage V C/E temp. ranges, V+ = 4.0V to 11V, 3.135 3.3 3.465 0mA < I < 300mA LOAD M temp. range, V+ = 4.0V to 11V, 3.135 3.3 3.465 0mA < I < 250mA LOAD C/E temp. ranges, V+ = 4.75V to 11V, 3.135 3.3 3.465 0mA < I < 500mA LOAD M temp. range, V+ = 4.75V to 11V, 3.135 3.3 3.465 0mA < I < 400mA LOAD Line Regulation 0.13 0.13 %/V Load Regulation I = 0mA to 500mA 0.001 0.001 %/mA LOAD 2 MAX748A/MAX763A