Power control circuit for hard disk drive

A power control circuit for a hard disk drive (HDD) includes a first control circuit, a second control circuit, a first connector connected to a power supply, the first and second control circuits, and a second connector connected to the first control circuit and the HDD. The power supply outputs a first voltage signal and a second voltage signal to the first and second control circuits via the first connector. The first control circuit converts the first and second voltage signals into a form compatible with a timing sequence of the HDD receiving voltage signals, and outputs the first and second voltage signals to the HDD via the second connector. The second control circuit controls the first control circuit.

BACKGROUND

1. Technical Field

The present disclosure relates to control circuits, and in particular, to a power control circuit for a hard disk drive (HDD).

2. Description of Related Art

Generally, an HDD includes a magnetic pickup head, a spindle motor, and a platter including a number of sectors. When the HDD is powered on, the spindle motor rotates the platter quickly to enable the magnetic pickup head to read data from the sectors. Since the HDD can employ a plurality of platters to increase storage volume, the magnetic pickup head must move rapidly and accurately to read data correctly. Accordingly, any vibration of the HDD may cause the magnetic pickup head to read data erroneously under the high-speed rotation of the platters.

DETAILED DESCRIPTION

Referring toFIG. 1, an exemplary embodiment of a power control circuit100for a hard disk drive (HDD)300includes a first connector10, a first control circuit20, a second control circuit30, and a second connector40. The first connector10is connected to the first control circuit20, the second control circuit30and a power supply200. The power supply200supplies power to the first control circuit20and the second control circuit30via the first connector10. The second connector40is connected to the first control circuit20and the HDD300. The first control circuit20supplies power to the HDD300via the second connector40. The second control circuit30is also connected to the first control circuit20to control the first control circuit20. In one embodiment, the power control circuit100is formed on a printed circuit board. The second connector40may be an external serial advanced technology attachment (SATA) power connector. The power supply200may be a computer power supply, such as an advanced technology extended power supply. The HDD300may be a SATA HDD.

Referring toFIG. 2, the first connector10includes a first power input pin1, a second power input pin4, and two ground pins2,3. When the first connector10is connected to the power supply200, the first power input pin1receives a first voltage signal, such as a 12V voltage signal, from the power supply200, and the second power input pin4receives a second voltage signal, such as a 5V voltage signal, from the power supply200, and the ground pins2,3are grounded. A capacitor C1includes a positive terminal connected to the first power input pin1and grounded via a capacitor C2, and a grounded negative terminal. A capacitor C3includes a positive terminal connected to the second power input pin4and grounded via a capacitor C4, and a grounded negative terminal.

The second connector40includes a first power output pin5, a grounded ground pin6, a detection pin7, and a second power output pin8. When the second connector40is connected to the HDD300, the first power output pin5outputs the first voltage signal to the HDD300, the second power output pin8outputs the second voltage signal to the HDD300. A capacitor C5includes a positive terminal connected to the first power output pin5and grounded via a capacitor C6, and a grounded negative terminal. A capacitor C7includes a positive terminal connected to the second power output pin8and grounded via a capacitor C8, and a grounded negative terminal. In one embodiment, the capacitors C1, C3, C5, and C7are electrolytic capacitors, and function as filtering elements to filter noise signals of high frequencies. The capacitors C2, C4, C6, and C8are ceramic capacitors, and function as filtering elements to filter noise signals of low frequencies. In other embodiments, the capacitors C1-C8may be deleted to save costs.

The first control circuit20includes four transistors Q1-Q4functioning as electric switches, and five resistors R1-R5. A first terminal of the transistor Q1is connected to the detection pin7of the second connector40, receiving a detection signal D, and connected to the second power input pin4of the first connector10via the resistor R1. A second terminal of the transistor Q1is connected to the second power input pin4of the first connector10via the resistor R2. A third terminal of the transistor Q1is grounded. A first terminal of the transistor Q2is connected to the second terminal of the transistor Q1, and grounded via the resistor R3. A second terminal of the transistor Q2is connected to the first power input pin1of the first connector10via the resistor R4. A third terminal of the transistor Q2is grounded. A first terminal of the transistor Q3is connected to the second terminal of the transistor Q2. A second terminal of the transistor Q3is connected to the first power output pin5of the second connector40. A third terminal of the transistor Q3is connected to the first power input pin1of the first connector10. A first terminal of the transistor Q4is connected to the second terminal of the transistor Q3via the resistor R5. A second terminal of the transistor Q4is connected to the second power input pin4of the first connector10. A third terminal of the transistor Q4is connected to the second power output pin8of the second connector40.

The second control circuit40includes four transistors Q5-Q8functioning as electric switches, five resistors R6-R10, and a manual switch K. A first terminal of the transistor Q5is connected to the second power input pin4of the first connector10via the resistor R6, and grounded via the manual switch K. A second terminal of the transistor Q5is connected to the second power input pin4of the first connector10via the resistor R7. A third terminal of the transistor Q5is grounded. A first terminal of the transistor Q6is connected to the second terminal of the transistor Q5. A second terminal of the transistor Q6is connected to the second power input pin4of the first connector10via the resistor R8. A third terminal of the transistor Q6is grounded. A first terminal of the transistor Q7is connected to the second terminal of the transistor Q6. A second terminal of the transistor Q7is connected to the second terminal of the transistor Q1of the first control circuit20. A third terminal of the transistor Q7is grounded. A first terminal of the transistor Q8is connected to the third terminal of the transistor Q4of the first control circuit20via the resistor R9, and grounded via the resistor R10. A second terminal of the transistor Q8is connected to the second terminal of the transistor Q6. A third terminal of the transistor Q8is grounded. In one embodiment, the transistors Q1-Q8are metal-oxide-semiconductor field-effect transistors (MOSFETs), and the first, second, and third terminals of each of the transistors Q1-Q8are gates, drains, and sources respectively. In this embodiment, the transistors Q1, Q2, Q4-Q8are N-channel MOSFETs, the transistor Q3is a P-channel MOSFET. The manual switch K includes a button, the manual switch K is closed when the button is press down, and the manual switch K is open when the button is without pressure.

In use, the first connector10is connected to the power supply200and the second connector40is connected to the HDD300, the first power input pin1receives the first voltage signal from the power supply200, and transmits the first voltage signal to the first control circuit20. The second power input pin4receives the second voltage signal from the power supply200, and transmits the second voltage signal to the first control circuit20and the second control circuit30. If a power connector of the HDD300is connected to the second connector40properly, because a pin of the power connector of the HDD300corresponding to the detection pin7is grounded, the detection pin7outputs the detection signal D at a low level to turn off the transistor Q1, the transistors Q2-Q4are turned on. The first voltage signal is transmitted to the first power output pin5via the transistor Q3, and further transmitted to the HDD300via the second connector400. The second voltage signal is transmitted to the second power output pin8via the transistor Q4, and further transmitted to the HDD300via the second connector400. Therefore, the HDD300is power on. In this embodiment, only when the transistor Q3is turn on, the first voltage signal is transmitted to the first terminal of the transistor Q4via the transistor Q3to turn on the transistor Q4, the second voltage signal can be transmitted to the second power output pin8via the transistor Q4. That is, the second connector40receives the second voltage signal after receiving the first voltage signal, and outputs the first voltage signal and the second voltage signal to the HDD300in order to satisfy a timing sequence of the HDD300receiving voltage signals.

When the manual switch K is open, the transistor Q5is turned on, the transistor Q6is turned off, the transistor Q7is turned on. The second terminal of the transistor Q7is at low level to turn off the transistor Q2, the transistors Q3, Q4are turned off. Therefore, the first and second voltage signals cannot be transmitted to the second connector40via the first control circuit20, and the second connector40cannot supply power to the HDD300accordingly.

When the manual switch K is closed, voltage at the first terminal of the transistor Q5is pulled down to a low level to turn off the transistor Q5, the transistor Q6is turned on, the transistor Q7is turned off, the first control circuit20works normally, the first and second voltage signals are transmitted to the second connector40. At this time, the second voltage signal is transmitted to the first terminal of the transistor Q8via the transistor Q4and the resistor R9to turn on the transistor Q8, the transistor Q7maintains a turned off state whether the manual switch K is closed or open. In summary, when the manual switch K is open, the first control circuit20cannot transmit the first and second voltage signals to the second connector40, and once the manual switch K is closed, the first control circuit20works normally.

When the power connector of the HDD300is received in the second connector40, vibration may occur, and some pins may suffer poor connection. If some pins of the HDD300are bad and power is supplied to the HDD300immediately, the HDD300may be damaged. Therefore, the power control circuit100employs the detection pin7, the first control circuit20, and the second control circuit30to protect the HDD300from damage. The detection pin7detects whether the power connector of the HDD300is connected to the second connector40properly, and only when the power connector of the HDD300is connected to the second connector40properly, does the first control circuit20begin operating. The first control circuit20converts the first and second voltage signals into a form to compatible with a timing sequence of the HDD300receiving voltage signals. With activation and deactivation of the manual switch K when the HDD300is connected to the second connector40and is not vibrating, the second control circuit30enables the first control circuit20to work normally. In other embodiments, if the power connector of the HDD300is connected to the second connector40without vibration, the second control circuit30can be deleted to save costs.