MAX857ESA+

The MAX856–MAX859 are high - efficiency, CMOS, stepup, DC - DC switching regulators for small, low input voltage or battery - powered systems. The MAX856/MAX858 accept a positive input voltage between 0.8V and VOUT and convert it to a higher, pin - selectable output voltage of 3.3V or 5V. The MAX857/MAX859 adjustable versions accept 0.8V to 6.0V input voltages and generate higher adjustable output voltages in the 2.7V to 6.0V range. Typical efficiencies are greater than 85%. Typical quiescent supply current is 25μA (1μA in shutdown). The MAX856–MAX859 combine a switch - mode regulator, N - channel power MOSFET, precision voltage reference, and power - fail detector in a single monolithic device. The MOSFET is a “sense - FET” type for best efficiency, and has a very low gate threshold voltage to ensure start - up with low battery voltages (0.8V typ).

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

Key features

• The MAX856–MAX859 are high - efficiency, CMOS, stepup, DC - DC switching regulators for small, low input voltage or battery - powered systems
• Combine ultra - low quiescent supply current and high efficiency to give maximum battery life
• An internal MOSFET power transistor permits high switching frequencies
• Internally set peak inductor current limits, permits the use of small, low - cost inductors
• The MAX856/MAX857 have a 500mA peak inductor current limit
• The MAX858/MAX859 have a 125mA peak inductor current limit
• 0.8V to 6.0V Input Supply Voltage
• 0.8V Typ Start - Up Supply Voltage
• 85% Efficiency at 100mA
• 25μA Quiescent Current
• 1μA Shutdown Mode
• 125mA and 500mA Switch - Current Limits Permit Use of Low - Cost Inductors
• Up to 500kHz Switching Frequency
• ±1.5% Reference Tolerance Over Temperature
• Low - Battery Detector (LBI/LBO)
• 8 - Pin SO and μMAX Packages