General Description

The MAX1836/MAX1837 high-efficiency step-down converters provide a preset 3.3V or 5V output voltage from supply voltages as high as 24V. Using external feedback resistors, the output voltage can be adjusted from 1.25V to VIN. An internal current-limited switching MOSFET delivers load currents up to 125mA (MAX1836) or 250mA (MAX1837).

The unique current-limited control scheme, operating with duty cycles up to 100, minimizes the dropout voltage (120mV at 100mA). Additionally, this control scheme reduces supply current under light loads to 12μA. High switching frequencies allow the use of tiny surface-mount inductors and output capacitors.

The MAX1836/MAX1837 step-down converters with internal switching MOSFETs are available in 6-pin SOT23 and 3mm x 3mm TDFN packages, making them ideal for low-cost, low-power, space-sensitive applications. For increased output drive capability, use the MAX1776 step-down converter that uses an internal 24V switch to deliver up to 500mA. For even higher currents, use the MAX1626/MAX1627 step-down controllers that drive an external P-channel MOSFET to deliver up to 20W.

Features

● 4.5V to 24V Input Voltage Range

● Preset 3.3V or 5V Output

● Adjustable Output from 1.25V to VIN

● Output Currents Up to 125mA (MAX1836) or 250mA (MAX1837)

● Efficiency Over 90

● 12μA Quiescent Current

● 3μA Shutdown Current

● 100 Maximum Duty Cycle for Low Dropout

● Small 6-Pin SOT23 and TDFN Packages

Applications

● 9V Battery Systems

● Notebook Computers

● Distributed Power Systems

● Backup Supplies

● 4mA to 20mA Loop Power Supplies

● Industrial Control Supplies

● Handheld Devices