Compact Switching Step-Down Converter By MAX639

Posted on Feb 6, 2014

Switch-mode power supplies are used in electronic circuits to increase (step up) or reduce (step down) voltage levels in the most efficient manner possible. Compared to linear voltage regulators, switch-mode supplies convert relatively little energy into heat. Their efficiency is thus high. This is a major advantage with compact power supplies in

Compact Switching Step-Down Converter By MAX639
Click here to download the full size of the above Circuit.

particular, since it sometimes makes forced-air cooling unnecessary. Building a switch-mode supply is considerably easier if you use components that have been specially developed for this application. One example of such an integrated step-down converter is the Maxim MAX639. This is designed for axed output voltage of +5V, with an input voltage ranging between +5. 5 and +11. 5V. Although this IC is primarily designed for axed output voltage, the output voltage can be tailored using a simple feedback network. With the given component values, resistors R3 and R4 determine the output voltage, with R3 = R4 [(Vout / 1. 28) 1] The value of R4 may lie between 10k and 10M, but a value of 100 k is a good choice for most applications. The maximum output current is 100mA. If desired, a different type of Schottky diode with similar specifications can be used in place of D1 (a 1N5817). Inductor L1 must be suitable for a maximum current of 500mA.

Leave Comment

characters left:

Related Circuits

  • New Circuits



    Popular Circuits

    The "BEAM Stepper" drive circuit
    Power Buffer Boosts Reference Current
    pcb fabrication Feasibility Question and Advice on CAD software
    Square Wave Oscillator
    Advanced Laser Diagnostics Laboratory
    Digital Radar Speedometer
    555 automatic power-protection circuit diagram