Systems and methods for reducing power dissipation in a disk drive including a fixed output voltage regulator
View Patent ↗A disk drive system includes a fixed output voltage regulator including an output terminal that provides a substantially fixed output voltage. A pluralities of loads are connected in parallel. A resistor is connected in series between the output terminal of the voltage regulator and the plurality of loads. The resistor causes a voltage provided to the plurality of loads to sag, as compared to the substantially fixed output voltage, when current is pulled, by one or more of the loads, through the resistor.
1. A disk drive system, comprising:
a fixed output voltage regulator including an output terminal that provides a substantially fixed output voltage;
a plurality of loads, each including a voltage supply terminal; and
an amplifier circuit configured to receive the substantially fixed output voltage of said voltage regulator and to provide a further voltage, to said voltage supply terminals of said loads, that is less than said substantially fixed output voltage of said fixed output voltage regulator, yet greater than a highest minimum operating voltage of said plurality of loads;
wherein said amplifier circuit includes:
an operational amplifier including a first input, a second input and an output, said first input connected to said output terminal of said fixed output voltage regulator, said output of said amplifier connected to said voltage supply terminals of said plurality of loads;
a first resistor connected between said output of said amplifier and said second input of said amplifier; and
a second resistor connected between the said second input of said amplifier and a low rail voltage;
wherein said first and second resistors are selected such that a voltage at said voltage supply terminals of said plurality of loads is less than said substantially fixed output voltage of said fixed output voltage regulator, yet greater than a highest minimum operating voltage associated with said loads.
2. A disk drive system, comprising:
a fixed output voltage regulator including an output terminal that provides a substantially fixed output voltage;
a plurality of loads, each including a voltage supply terminal;
a transistor including a source, a drain and a gate, said source connected to said output terminal of said fixed output voltage regulator, said drain connected to said voltage supply terminals of said plurality of loads; and
a resistor divider network to produce a bias voltage that is provided to said gate of said transistor, said bias voltage being selected such that a voltage at said drain is less than said substantially fixed output voltage of said fixed output voltage regulator, yet greater than a highest minimum operating voltage of said plurality of loads.
3. The system of claim 2 , wherein said transistor comprises a p-channel field effect transistor.
4. The system of claim 2 , wherein said transistor acts as a voltage controlled resistor, said bias voltage specifying a resistance thereof.
5. The system of claim 4 , wherein the resistor network includes:
a first resistor connected between said gate and said output terminal of said voltage regulator; and
a second resistor connected between said gate and a low rail voltage.
6. The system of claim 5 , wherein said amplifier circuit is configured to have a gain of less than one.