Patent ID: 7545132

Claim:
A method of controlling inductor current levels during a second time interval (N+1) having a beginning and a duty-cycle, the second time interval (N+1) following a first time interval (N), the method comprising: sampling a first inductor current level (I(n)) at or substantially at the beginning of the first time interval (N); and controlling the duty-cycle in the second time interval (N+1) so that a peak inductor current level, (I p (n+1)), during said second time interval (N+1) does not exceed a predetermined maximum current level, (I LIMIT ), wherein controlling the duty-cycle includes calculating a maximum allowable duty-cycle using the equation: D MAX ⁡ ( n ) = ( I LIMIT - I ⁡ ( n ) ) ⁢ L · f s V i ⁡ ( n ) + V o ⁡ ( n ) V i ⁡ ( n ) ⁢ ( 1 - D ⁡ ( n - 1 ) ) - 1 where: I(n) is current at or near the beginning of the first time interval (N); L is inductance; f s is frequency; V i (n) is one or more input voltages; V o (n) is one or more output voltages; and D(n−1) is a duty-cycle for the first time interval (N) that was calculated during time interval (N−1) sequentially before the first time interval (N).