03-05-2011, 12:41 PM
Abstract
Voltage required in the modern electronic systemsare single or multiple regulated voltages such as3.3 V, 5V, 12V, -5V, or –12V, etc. It can be suppliedby using DC/DC converters. The operations ofStep-Down DC/DC converter is introduced in theapplication note. A practical constant voltage,DC/DC step-down converter design based on theAIC1563 is also illustrated to help the readers inthe circuit designs and applications.
Operations of Step-Down DC/DCConverter
The voltage and current waveforms in the circuitare shown in Fig. 2. The control circuit is used todetect the output voltage level and generates adriving signal to turn on or turn off on the powerswitch (SW). The power switch can be controlledby using different methods, such as pulse widthmodulation (PWM), pulse frequency modulation(PFM), or pulse skipping modulation (PSM),depends on the applications. As for the outputvoltage stability, it is maintained by controlling theduty cycle without losing energy. This may beillustrated by examining the energy stored in theinductor.
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