アプリケーションノート3844

Making a Voltage Inverter from a Buck (Step-Down) DC-DC Converter

筆者: Len Sherman

Abstract: Any step-down DC-DC converter can be used as an inverter with no changes to the operating schematic. This application note shows how to relabel the connector points to do this.

Any step-down DC-DC converter can be used as an inverter with no changes to the operating schematic. The only difference between the normal step-down application and inverting operation is the labels of the connection points. The step-down DC-DC converter's VOUT node is GND in the inverter. The step-down DC-DC converter's GND node is -VOUT in the inverter. Input power, VIN, is the same node in both circuits.

When using a step-down DC-DC converter as an inverter, there are some limitations. The voltage difference between the input and the negative output must be less than the step-down DC-DC converter's maximum operating input voltage. In essence, a step-down DC-DC converter with maximum input of 12V can be used to convert 5V to -7V, but not more.

In addition, the minimum input voltage of the inverting circuit must be greater than the minimum operating voltage of the step-down IC, minus one diode drop. That is because on start-up, there is initially no negative output voltage. Consequently, the step-down IC is biased only by the input voltage, less a diode forward drop.

Figure 1. Block diagram shows a generic step-down DC-DC converter as both a normal step-down (Figure 1a) and connected as a negative-output voltage inverter (Figure 1b).
Figure 1. Block diagram shows a generic step-down DC-DC converter as both a normal step-down (Figure 1a) and connected as a negative-output voltage inverter (Figure 1b).



次のステップ
EE-Mail EE-Mail配信の登録申し込みをして、興味のある分野の最新ドキュメントに関する自動通知を受け取る。
ダウンロード ダウンロード、PDFフォーマット (29kB)  

© May 23, 2006, Maxim Integrated Products, Inc.
このウェブサイトのコンテンツは米国および各国の著作権法によって保護されています。コンテンツの複製を希望される場合は、お問い合わせください

APP 3844: May 23, 2006
アプリケーションノート3844, AN3844, AN 3844, APP3844, Appnote3844, Appnote 3844