EVALUATION KIT AVAILABLE MAX756/MAX757 3.3V/5V/Adjustable-Output, Step-Up DC-DC Converters General Description Features The MAX756/MAX757 are CMOS step-up DC-DC switch- Operates Down to 0.7V Input Supply Voltage ing regulators for small, low input voltage or battery-pow- 87% Efficiency at 200mA ered systems. The MAX756 accepts a positive input voltage down to 0.7V and converts it to a higher pin- 60A Quiescent Current selectable output voltage of 3.3V or 5V. The MAX757 is 20A Shutdown Mode with Active Reference and an adjustable version that accepts an input voltage down LBI Detector to 0.7V and generates a higher adjustable output voltage in the range from 2.7V to 5.5V. Typical full-load efficiencies 500kHz Maximum Switching Frequency for the MAX756/MAX757 are greater than 87%. 1.5% Reference Tolerance Over Temperature The MAX756/MAX757 provide three improvements over previous devices. Physical size is reducedthe high Low-Battery Detector (LBI/LBO) switching frequencies (up to 0.5MHz) made possible by 8-Pin DIP and SO Packages MOSFET power transistors allow for tiny (<5mm diameter) surface-mount magnetics. Efficiency is improved to 87% Ordering Information (10% better than with low-voltage regulators fabricated in bipolar technology). Supply current is reduced to 60A PART TEMP. RANGE PIN-PACKAGE by CMOS construction and a unique constant-off-time MAX756CPA 0C to +70C 8 Plastic DIP pulse-frequency modulation control scheme. MAX756CSA 0C to +70C 8 SO Applications MAX756C/D 0C to +70C Dice* 3.3V to 5V Step-Up Conversion MAX756EPA -40C to +85C 8 Plastic DIP Palmtop Computers MAX756ESA -40C to +85C 8 SO MAX757CPA Portable Data-Collection Equipment 0C to +70C 8 Plastic DIP MAX757CSA 0C to +70C 8 SO Personal Data Communicators/Computers MAX757C/D 0C to +70C Dice* Medical Instrumentation MAX757EPA -40C to +85C 8 Plastic DIP 2-Cell & 3-Cell Battery-Operated Equipment MAX757ESA -40C to +85C 8 SO Glucose Meters * Dice are tested at T = +25C only. A Functional Diagrams Pin Configurations Typical Operating Circuit INPUT TOP VIEW 2V to V OUT 1 SHDN 8 LX 2 7 3/5 GND 150F OUTPUT MAX756 3 22H 6 5V at 200mA REF OUT 5 or LBI 4 5 LBI 1N5817 LBO 8 3.3V at 300mA 1 SHDN LX DIP/SO 100F MAX756 2 6 3/5 OUT 1 SHDN 8 LX 2 7 FB GND MAX757 3 4 3 LOW-BATTERY 6 OUT REF REF LBO DETECTOR OUTPUT 4 5 LBI LBO GND Pin Configurations appear at end of data sheet.0.1F 7 Functional Diagrams continued at end of data sheet. DIP/SO UCSP is a trademark of Maxim Integrated Products, Inc. For pricing, delivery, and ordering information, please contact Maxim Direct 19-0113 Rev. 2 1/95 at 1-888-629-4642, or visit Maxims website at www.maxim integrated.com. 3.3V/5V/Adjustable-Output, Step-Up DC-DC Converters General Description Features The MAX756/MAX757 are CMOS step-up DC-DC switch- Operates Down to 0.7V Input Supply Voltage ing regulators for small, low input voltage or battery-pow- 87% Efficiency at 200mA ered systems. The MAX756 accepts a positive input voltage down to 0.7V and converts it to a higher pin- 60A Quiescent Current selectable output voltage of 3.3V or 5V. The MAX757 is 20A Shutdown Mode with Active Reference and an adjustable version that accepts an input voltage down LBI Detector to 0.7V and generates a higher adjustable output voltage in the range from 2.7V to 5.5V. Typical full-load efficiencies 500kHz Maximum Switching Frequency for the MAX756/MAX757 are greater than 87%. 1.5% Reference Tolerance Over Temperature The MAX756/MAX757 provide three improvements over previous devices. Physical size is reducedthe high Low-Battery Detector (LBI/LBO) switching frequencies (up to 0.5MHz) made possible by 8-Pin DIP and SO Packages MOSFET power transistors allow for tiny (<5mm diameter) surface-mount magnetics. Efficiency is improved to 87% Ordering Information (10% better than with low-voltage regulators fabricated in bipolar technology). Supply current is reduced to 60A by CMOS construction and a unique constant-off-time pulse-frequency modulation control scheme. Applications 3.3V to 5V Step-Up Conversion Palmtop Computers Portable Data-Collection Equipment Personal Data Communicators/Computers Medical Instrumentation 2-Cell & 3-Cell Battery-Operated Equipment Glucose Meters * Dice are tested at T = +25C only. A AVAILABLEMAX756/MAX757 3.3V/5V/Adjustable-Output, Step-Up DC-DC Converters ABSOLUTE MAXIMUM RATINGS Supply Voltage (OUT to GND) ....................................-0.3V, +7V Operating Temperature Ranges: Switch Voltage (LX to GND) ........................................-0.3V, +7V MAX75 C ........................................................0C to +70C Auxiliary Pin Voltages (SHDN, LBI, LBO, REF, MAX75 E ......................................................-40C to +85C 3/5, FB to GND) ........................................-0.3V, (V + 0.3V) Junction Temperature......................................................+150C OUT Reference Current (I ) ....................................................2.5mA Storage Temperature Range............................... -65to +160C REF Continuous Power Dissipation (T = +70C) Lead Temperature (soldering, 10sec) ........................... +300C A Plastic DIP (derate 9.09mW/C above +70C) .............727mW SO (derate 5.88mW/C above +70C)..........................471mW Stresses beyond those listed under Absolute Maximum Rating 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 (Circuits of Figure 1 and Typical Operating Circuit, V = 2.5V, I = 0mA, T = T to T , unless otherwise noted.) IN LOAD A MIN MAX PARAMETER CONDITIONS MIN TYP MAX UNITS MAX756, 3/5 = 0V, 0mA < I < 200mA 4.8 5.0 5.2 LOAD 2V < V < 3V MAX756, 3/5 = 3V, 0mA < I < 300mA Output Voltage IN 3.17 3.30 3.43 V LOAD MAX757, V = 5V, 0mA < I < 200mA OUT LOAD 4.8 5.0 5.2 I = 10mA Minimum Start-Up Supply Voltage 1.1 1.8 V LOAD Minimum Operating Supply I = 20mA LOAD 0.7 V Voltage (once started) Quiescent Supply Current in I = 0mA, 3/5 = 3V, LBI = 1.25V, V = 3.47V, LOAD OUT 60 A 3.3V Mode (Note 1) FB = 1.3V (MAX757 only) Battery Quiescent Current Output set for 3.3V 60 A Measured at V in Figure 1 IN Shutdown Quiescent Current SHDN = 0V, LBI = 1.25V, 3/5 = 3V, V = 3.47V, OUT 20 40 A (Note 1) FB = 1.3V (MAX757 only) Reference Voltage No REF load, C = 0.1F 1.23 1.25 1.27 V REF 3/5 = 3V, -20A < REF load < 250A, C = 0.22F Reference-Voltage Regulation 0.8 2.0 % REF LBI Input Threshold With falling edge 1.22 1.25 1.28 V LBI Input Hysteresis 25 mV I = 2mA LBO Output Voltage Low 0.4 V SINK LBO Output Leakage Current LBO = 5V 1 A SHDN, 3/5 Input Voltage Low 0.4 V SHDN, 3/5 Input Voltage High 1.6 V LBI = 1.25V, FB = 1.25V, SHDN = 0V or 3V, SHDN, 3/5, FB, LBI Input Current 100 nA 3/5 = 0V or 3V FB Voltage MAX757 1.22 1.25 1.28 V Output Voltage Range MAX757, I = 0mA (Note 2) 2.7 5.5 V LOAD Note 1: Supply current from the 3.3V output is measured with an ammeter between the 3.3V output and OUT pin. This current correlates directly with actual battery supply current, but is reduced in value according to the step-up ratio and efficiency. Note 2: Minimum value is production tested. Maximum value is guaranteed by design and is not production tested. 2 Maxim Integrated