Abstract: A resistor/capacitor identification detection (RCID) circuit may provide system level identification of hardware (e.g. circuit board ID) through a single pin interface, by identifying up to a specified number of more than two quantized RC time constant states by measuring the discharge and charge times of an external RC circuit coupled to the single pin. The RCID circuit may initiate the discharge followed by a charging of the external RC circuit. The signal developed at the signal pin may be provided to the input of a threshold detector, with the threshold set at a specified percentage of a supply voltage used for operating the RCID circuit. The digitized output of the threshold detector may be used to gate a counter, after having been filtered through an input glitch rejection filter. A resolution of the counter may be determined by a high frequency clock used for clocking the counter. The numeric values of the charge and discharge times may be stored in data registers comprised in the RCID circuit.

Abstract: A fan controller may be integrated in silicon and may use an embedded microcontroller to implement a digital fan control algorithm. The microcontroller may continually monitor temperature and sample the speed of the controlled fan. The speed of the fan may be compared to RPM values fitted on a desired curve that is representative of the Temperature-versus-RPM function for the controlled fan. The fan control algorithm may be based on a ramp-rate closed-loop controller (RRCC), which may be operated to drive the fan to the desired speed at different rates, depending on the difference between the desired RPM and the actual RPM of the fan. The fan may also provide a Fan ID feedback signal to the microcontroller, which may use the Fan ID feedback signal upon system start-up to initialize the RRCC range settings and select the appropriate Temperature-versus-RPM function curve based on pre-determined values for the given fan.

Abstract: A system and method for controlling a fan is disclosed. In one embodiment, a fan controller is integrated in silicon and uses an embedded microcontroller to implement a digital fan control algorithm. The microcontroller may continually monitor temperature and sample the speed of the controlled fan. The speed of the fan may be compared to RPM values fitted on a desired curve that is representative of the Temperature-versus-RPM function for the given controlled fan. The fan control algorithm may be based on a PID compensator or a Ramp Rate Closed-loop controller (RRCC), which may be operated to drive the fan to the desired speed. The fan may also provide a Fan ID feedback signal to the microcontroller, which may use the Fan ID feedback signal upon system start-up to initialize the PID compensator gain settings or the RRCC parameter settings, and select the appropriate Temperature-versus-RPM function curve based on pre-determined values for the given fan.