Analog Devices AN-1149 Application Note Buck/Boost Regulators

About this manual

This document is an application note titled "How to Apply DC-to-DC Step-Down/Step-Up (Buck/Boost) Regulators" published by Analog Devices. It focuses on the design and application of buck/boost converters, which can generate output voltages less than, greater than, or equal to the input voltage. The text describes the internal topology of these regulators, which contain four switches, two capacitors, and an inductor, and explains how they operate in buck mode, boost mode, and buck/boost mode to maintain regulation across varying input voltages.

What's inside

• Introduction
• Buck/Boost Regulators
• Buck/Boost Regulators Improve System Efficiency
• Buck/Boost Regulator Key Specifications and Definitions
• Output Voltage Range Options
• Ground or Quiescent Current
• Shutdown Current
• Soft Start
• Switching Frequency
• Thermal Shutdown (TSD)

Specifications

Frequently asked questions

What is the primary function of a buck/boost regulator?

It is used to generate an output voltage that is less than, greater than, or equal to the input voltage.

How does a buck/boost regulator improve battery life in portable systems?

It allows the system to operate down to the minimum practical battery voltage (e.g., 3.0 V), utilizing most of the stored energy compared to a low dropout regulator.

What happens if the junction temperature rises above the specified limit?

The thermal shutdown circuit turns the regulator off until the on-chip temperature drops below the preset limit.