Understanding The Data Sheet Key To Effective Circuit Design Focus: IC data sheets often omit data needed by designers or worse yet present erroneous data as illustrated here with examples taken from voltage reference and switching regulator data sheets. For example, a voltage reference data sheet shows output impedance with and without a 1-uF output cap, but does not specify key test conditions such as output current or capacitor dielectric. Even worse, the capacitance value listed is wrong. As the author explains, these mistakes will influence the reference’s stability, noise and PSRR performance. With the switching regulator, the vendor has failed to characterize its spectral output under pulse-skipping conditions, which as the author shows, produces significant content at frequencies well below the switching frequency leading to high levels of output ripple at these frequencies, and potentially excessive input ripple and EMI. The author concludes by advising designers to verify IC performance using vendor-supplied EVMs and by measuring device performance in their prototypes.
What you’ll learn: - How to catch potential IC data sheet errors and omissions when evaluating, voltage references, linear and switching voltage regulators, and class D audio amplifiers
Notes: This article appeared in the July 2012 print edition of Power Electronics Technology.
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Author & Publication: Steve Sandler, Picotest, Power Electronics Technology, Jun 27 2012
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