IC PMOS Schottky reverse bias protection structure

A system for controlling a component receiving electrical energy, comprising:

• a system power supply;
• a component for providing a predetermined system function;
• a component driver circuit operably coupled to the system power supply and the component, and adapted to provide driver signals to the component to effectuate the predetermined system function;
• and
• a protection structure associated with the component driver circuit, wherein the protection structure is operable to substantially prevent a reverse current from conducting from the component driver circuit to the system power supply in a reverse bias condition, and operable to substantially pass a system power supply voltage value to the component driver circuit in a forward bias condition, wherein the protection structure comprises:
• a Schottky diode structure having a cathode coupled to the system power supply, and an anode;
• and
• a PMOS transistor structure having a source coupled to the cathode, a gate coupled to a system ground potential, a drain coupled to the component control circuit, and a backgate coupled to the anode of the Schottky diode.

A fan driver circuit, comprising:

• a fan controller circuit operable to generate one or more control signals for operating a fan motor;
• a fan driver circuit operably coupled to the fan controller circuit and operable to drive the fan motor in response to the one or more control signals;
• a power supply operable to provide energy to the fan controller circuit and the fan driver circuit, respectively;
• a PMOS-Schottky protection structure;
• and
• a fan driven by the fan motor,
• wherein if the fan is properly connected to the fan motor, a forward biased condition results, and the PMOS-Schottky protection structure is operable to couple a voltage of the power supply to the fan driver circuit with a voltage drop thereacross which is less than a forward bias diode voltage drop, and
• wherein if the fan is improperly connected to the fan motor, a reverse bias condition results, and the PMOS-Schottky protection is operable to prevent a reverse current from conducting from the fan driver circuit to the power supply, and
• wherein the PMOS-Schottky protection structure comprises:
• a PMOS transistor having a source terminal, a gate terminal, a drain terminal and a backgate;
• and
• a Schottky diode structure having an anode terminal coupled to the source terminal and a cathode terminal coupled to the backgate of the PMOS transistor, respectively,
• wherein under forward bias conditions, the gate terminal is at a low voltage with respect to the source terminal, thereby causing the PMOS transistor to turn on and conduct current from the power supply to the fan driver circuit, and
• wherein under reverse bias conditions, the gate terminal is at a high voltage with respect to the source terminal, thereby causing the PMOS transistor to turn off, and the backgate of the PMOS transistor is at a high voltage with respect to the source terminal, thereby causing the Schottky diode to be reverse biased and prevent current from conducting therethrough.