| US 7,525,823 B2 | ||
| Switch mode power supply systems | ||
| Johan Piper, Cambridgeshire (United Kingdom); and David M. Garner, London (United Kingdom) | ||
| Assigned to Cambridge Semiconductor Limited, (United Kingdom) | ||
| Filed on Jul. 21, 2006, as Appl. No. 11/490,877. | ||
| Claims priority of application No. 06134936 (GB), filed on Jul. 07, 2006. | ||
| Prior Publication US 2008/0007982 A1, Jan. 10, 2008 | ||
| This patent is subject to a terminal disclaimer. | ||
| Int. Cl. H02M 3/335 (2006.01) | ||
| U.S. Cl. 363—21.16 [363/21.11; 363/21.18] | 36 Claims |
| 1. A system for estimating the output current of a Switch Mode Power Supply (SMPS), the SMPS including a transformer with
at least a primary winding coupled to an input of the SMPS and a secondary winding coupled to an output of the SMPS and having
a power switching device to switch power to the primary winding of the transformer, the system comprising:
a primary current sense input to sense a primary current in the primary winding of the transformer;
a charge signal input to sense a charge signal dependent on a charging time of the transformer;
a discharge signal input to sense a discharge signal dependent on a discharging time of the transformer;
at least one averager; and
a calculator;
wherein the primary current is averaged by the averager over at least a switching cycle of the SMPS; and
wherein the calculator estimates the output current of the SMPS using the averaged primary current, the charge signal and
the discharge signal.
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