Articles by Steve Sandler

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A Bode Plot Without Access to the Control Loop

This extreme measurement seems more impossible than difficult.  The traditional stability assessment method for voltage regulators is the Bode plot.  Access to the control loop is required and a small signal is injected into the control loop, usually via a resistor, placed at the top of the voltage sense divider. Without access to this voltage divider, there isn’t a place to inject a signal into the control loop, and therefore the Bode plot is seemingly impossible…


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Selecting a VRM Output Inductor

A consideration that is often neglected is the impact of the self-resonant frequency (SRF) or parallel equivalent capacitance, Cp, which is related to SRF. In this article, Steve Sandler focuses on the impact of the inductor SRF on switching regulator performance.


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The Goldilocks TDR

It pains me to say this, but there is such a thing as turning the TDR up too high and it is also easy not to have enough. If there is a “too high,” and a “not high enough,” there must also be a “just‐right,” or Goldilocks, setting. Using measurements, and a smattering of math, the Goldilocks setting answers
will be clear. Read on to find out how.


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