Features: Operates Down to 0.7V Input Supply Voltage
87% Efficiency at 200mA
60A Quiescent Current
20A Shutdown Mode with Active Reference and
LBI Detector
500kHz Maximum Switching Frequency
±1.5% Reference Tolerance Over Temperature
Low-Battery Detector (LBI/LBO)
8-Pin DIP and SO PackagesApplication3.3V 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 MetersPinout
SpecificationsSupply Voltage (OUT to GND).......................................-0.3V, +7V
Switch Voltage (LX to GND)..........................................-0.3V, +7V
Auxiliary Pin Voltages (SHDN, LBI, LBO, REF,
3/5, FB to GND)............................................-0.3V, (VOUT + 0.3V)
Reference Current (IREF)....................................................2.5mA
Continuous Power Dissipation (TA = +70°C)
Plastic DIP (derate 9.09mW/°C above +70°C) ..............727mW
SO (derate 5.88mW/°C above +70°C)...........................471mW
Operating Temperature Ranges:
MAX75_C_ _ ........................................................0°C to +70°C
MAX75_E_ _......................................................-40°C to +85°C
Junction Temperature.....................................................+150°C
Storage Temperature Range............................. -65°to +160°C
Lead Temperature (soldering, 10sec)............................ +300°C
DescriptionThe MAX756/MAX757 are CMOS step-up DC-DC switch- ing regulators for small, low input voltage or battery-pow- ered systems. The MAX756 accepts a positive input voltage down to 0.7V and converts it to a higher pin- selectable output voltage of 3.3V or 5V. The MAX757 is an adjustable version that accepts an input voltage down to 0.7V and generates a higher adjustable output voltage in the range from 2.7V to 5.5V. Typical full-load efficiencies for the MAX756/MAX757 are greater than 87%.
The MAX756/MAX757 provide three improvements over previous devices. Physical size is reduced-the high switching frequencies (up to 0.5MHz) made possible by MOSFET power transistors allow for tiny (<5mm diameter) surface-mount magnetics. Efficiency is improved to 87% (10% better than with low-voltage regulators fabricated in bipolar technology). Supply current of MAX756 is reduced to 60A by CMOS construction and a unique constant-off-time pulse-frequency modulation control scheme.
MAX756 Data Sheet
