Patent ID: 7538453
Filing Date: 2009-05-26
Classification: H02J

Abstract:
1. A fan power supply system, comprising: a pair of voltage supplies, one of the pair of voltage supplies producing a higher voltage than the other one of the pair of voltage supplies; a switch for selecting one of the pair of the voltage supplies in response to a control signal; a DC/DC converter connected to the selected one of the pair of voltages supplies for producing a current greater than current fed to the DC/DC converter by the selected one of the pair of voltage supplies; a fan fed by the current produced by the DC/DC converter, such fan producing a train of pulses representative of the rotational speed of the fan; a microcontroller for encoding the train of pulses produced by the fan as a function of whether the selected one of the pair of voltages has the higher voltage or the lower voltage; a decoder for producing the control signal in accordance with the encoding by the microcontroller.