Measuring output current in a buck SMPS

A sample and hold circuit takes a sample of the current flowing through an inductor of a buck switched-mode power supply (SMPS) at substantially the middle of the low side portion (50 percent point during low side switch ON) of the pulse width modulation (PWM) period. This sample of the current thro...

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Bibliographische Detailangaben
Hauptverfasser:	Ellison Cliff, Dearborn Scott
Format:	Patent
Sprache:	eng
Schlagworte:	APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC,OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWERSUPPLY SYSTEMS CONTROL OR REGULATION THEREOF CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUTPOWER CONVERSION OR DISTRIBUTION OF ELECTRIC POWER ELECTRICITY GENERATION MEASURING MEASURING ELECTRIC VARIABLES MEASURING MAGNETIC VARIABLES PHYSICS TESTING
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Beschreibung
Zusammenfassung:	A sample and hold circuit takes a sample of the current flowing through an inductor of a buck switched-mode power supply (SMPS) at substantially the middle of the low side portion (50 percent point during low side switch ON) of the pulse width modulation (PWM) period. This sample of the current through the SMPS inductor during the low side ON 50% point may be considered as the "average" or "DC output" current of the SMPS, and taken every time at precisely the same low side ON 50%. A constant current source and sink are used to charge and discharge a timing capacitor whose voltage charge is monitored by a high speed voltage comparator to provide precise sample timing.