Self-Starting Can Be Hard To Do–Understanding Power-On-Reset Requirements In Regulators And Bandgaps

Focus:

Many integrated circuits require special handling at power-up. Analog and digital circuits may need to be placed in predictable conditions at start-up. To do that, we use circuits that are commonly called power-on-reset (POR) circuits. POR makes sure that there is an orderly and predictable sequence of events during power-up. This article discusses start-up problems afflicting voltage regulators, voltage references, and bandgap references, explaining why these problems occur and what circuit techniques can be used to prevent or fix these problems. The article also introduces a tool that aids in the design and analysis of Brokaw bandgap reference circuits. The role of POR circuits in ensuring startup is discussed and three example parts with the POR circuit (a bandgap reference, a DAC, and a digital potentiometer) are discussed.

What you’ll learn:

• How to prevent or fix common startup problems experienced by voltage references and regulators
• How to understand the role of power-on reset circuits

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Author & Publication:

Bill Laumeister, Maxim Integrated Products, Sunnyvale, Calif., How2Power Today, Nov 30 2011

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