DIGITAL CONTROL UNIT HAVING A TRANSIENT DETECTOR FOR CONTROLLING A SWITCHED MODE POWER SUPPLY

摘要

A switched mode power supply (SMPS) comprising a feedback unit, voltage feed forward (VFF) compensation signal generator (1211) and a transient detector (701) is disclosed. A VFF compensation signal is only applied to the output of the feedback unit when a transient is detected by the transient detector (701) on the input voltage of the SMPS, thereby a saving power and computation time. The transient detector (701) comprises a first comparator (402) to detect that a positive transient has occurred if a difference signal is greater than a positive threshold level Cb1Q); a second comparator (403) to determine if the difference signal is within a predetermined range of positive values and output a result that indicates if the difference signal is within the predetermined range of positive values; and a first calculator (405) to detect that a positive transient has occurred if, out of a first predetermined number (N1) of consecutive results of the output of the second comparator (403), there is at least a second predetermined number (X1) of results indicating that the difference signal is within the predetermined range of positive values. The transient detector comprises further features for similarly detecting a negative transient. The transient detector (701) is particularly good at dealing with measurement noise and light load induced noise.