Switching-Regulator Insights: Achieving Longer Battery Life in DSP Systems

Focus:

A new stepdown switching regulator architecture provides good regulation, high efficiency, and fast response in DSP-based, battery-powered applications. The regulator employs a constant on-time, valley-current-mode control scheme (also known as leading-edge modulation) which offers advantages versus constant-frequency peak-current control. With that as background, the article discusses the use of dynamic voltage adjustment of a DSP's core voltage as a means of saving power and conserving battery life. The article explains the benefits of using an external regulator to perform dynamic voltage adjustment and presents two methods for doing so using a synchronous buck converter. The regulator used to explain these methods, the ADP2102, employs the new regulator architecture described in the article.

What you’ll learn:

• How to dynamically adjust the core voltage of a digital signal processor (DSP) to save power at reduced clock speeds
• How to under the operation and benefits of a constant on-time, valley-current-mode control scheme (also known as leading-edge modulation)
• How to overcome limitations such as minimum on-time, poor transient response, and instability at duty cycles greater than 50%, which are associated with constant-frequency peak-current control

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Author & Publication:

Sridhar Gurram, Oliver Brennan, Tim Wilkerson, Analog Devices, San Jose, Calif., How2Power Today, Sep 17 2009

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