Patent ID: 6023155
Filing Date: 2000-02-08
Classification: G05F,H02M

Abstract:
A secure data system power supply having an input coupleable to an input voltage line and an output coupleable to a secure data system and providing isolation between the input voltage line and the secure data system, the secure data system power supply comprising:a constant power flyback converter coupled between the input voltage line and the secure data system, the constant power flyback converter taking as an input from the input voltage line a constant power input and providing at a converter output an output signal for use in powering the secure data system, wherein the constant power flyback converter further comprises:a transformer having a primary winding and a secondary winding, a first end of the primary winding being coupled to the input voltage line;a power switching device coupled to a second end of the primary winding and providing a current path for current in the primary winding when the power switching device is conducting; anda constant power peak current controller providing a control signal to the power switching device to control conduction of the power switching device such that information communicated within the secure data system is undetectable from the input voltage line, wherein the constant power peak current controller controls the power switching device such that a constant quantity of power is applied to the primary winding of the transformer and such that a peak magnitude of the current in the primary winding of the transformer maintains a substantially constant value over a range of input voltages on the input voltage line; anda shunt voltage regulator coupled to the converter output and maintaining the output signal at a substantially constant voltage.