How2Power.com - Building a Power Supply That Works

Building a Power Supply That Works

Focus:

An alternative title could have been, "Building your first dc-dc converter" using a dc-dc converter IC. This 8-page application note provides start-to-finish guidance on designing your first dc-dc converter to help designers avoid the usual fate of first attempts---a converter that does not work. The author, who is not named, brings to bear his or her "success and failureâ€¦on dozens of power-supply designs." The app note discusses selection of the following techniques and components: topology (buck or boost), IC (dc-dc controllers versus dc-dc converters with integrated switches), MOSFETs, control scheme (PWM versus PFM), and switching frequency. The impact of high switching frequencies on inductor and capacitor size is discussed, though there's no mention on the negative effect of higher frequencies on efficiency. App note also discusses where to find design equations and how to use spreadsheets to perform necessary calculations. Additional guidance is given on selection of the inductor, input capacitor, output capacitor, soft-start capacitor, and toff resistor. Adjustment of calculated values to match actual available component values is discussed. Guidance is given on pc-board layout including component layout, grounding, signal routing. Other topics briefly covered include design verification, efficiency , load and line regulation, and temperature sensitivity.

What you’ll learn: