DC converter with independently controlled outputs
A DC converter comprises a single primary circuit which is coupled to each of a plurality of output circuits in respective time periods, the coupling being provided by switching in the output circuits. Each output circuit produces a respective output voltage and a respective feedback signal which is coupled as a control signal to the primary circuit during the respective time periods, so that each output voltage is regulated substantially independently of each other output voltage. The time periods for the different output circuits can be equal or different, and can be dynamically changed depending on error voltages of the output circuits.
1. Apparatus for producing N output voltages, where N is an integer greater than one, comprising:
means for coupling a single primary circuit of a DC converter to each of N output circuits of the DC converter in respective time periods, the output circuits each producing a respective one of the N output voltages; and
means for coupling a respective feedback signal of each of the output circuits as a feedback control signal to the primary circuit of the DC converter during the respective time periods for regulating each output voltage substantially independently of each other output voltage.
2. Apparatus as claimed in claim 1 wherein the DC converter is operated in discontinuous current mode for producing each of the N output voltages.
3. Apparatus as claimed in claim 1 wherein the DC converter is a forward converter.
4. Apparatus as claimed in claim 1 wherein the DC converter is a flyback converter.
5. Apparatus as claimed in claim 1 wherein the means for coupling the primary circuit to each of the N output circuits in respective time periods comprises means for selectively switching each of at least N-1 of the output circuits to couple it to a secondary winding of a transformer of the DC converter.
6. Apparatus as claimed in claim 1 and comprising means for producing the respective time periods sequentially and cyclically for the N output circuits.
7. Apparatus as claimed in claim 6 and including means for producing the respective time periods equally for the N output circuits.
8. Apparatus as claimed in claim 6 and including means for producing the respective time periods with different durations for different ones of the N output circuits.
9. Apparatus as claimed in claim 6 and including means for producing the respective time periods with durations dependent upon error voltages of the output circuits.