Patent Application
20130003428
1. Technical Field
The disclosure generally relates to a power supply system, and an electrical device such as a consumer electrical device using the power supply system.
2. Description of Related Art
Power supply systems are widely used in modern electrical devices, such as video players, mobile phones, and digital versatile disc (DVD) players, for example. These electrical devices generally include a plurality of function circuits to carry out corresponding operations. For example, a typical DVD player includes a video process circuit configured for processing video data, an audio process circuit configured for processing audio signals, and a driving circuit for driving a cassette mechanism of the DVD player. The power supply system of the DVD player is configured to convert an alternating current (AC) voltage to a plurality of direct current (DC) voltages, and output the DC voltages to the function circuits to power on the function circuits and enable them to operate. In normal use, the function circuits are not required to all start working at the same time. Therefore, a power supply system that can provide operation voltages to the function circuits at desired starting times of the function circuits is desired.
The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of the application. The drawings illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure.
Reference will now be made in detail to the present preferred embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.
In the present disclosure, the electrical device can for example be a DVD player, a tablet computer, a notebook, or a mobile phone. Each such electrical device includes a plurality of function circuits that are capable of being enabled to work when receiving required DC operation voltages, and thereby are able to carry out corresponding functions. In the following description, the electrical device is a DVD player, as an example.
Referring to
The power supply system 100 includes a power supply circuit 110 and a control unit 130. The power supply circuit 110 is configured to generate one or more required DC operation voltages either by rectifying an external AC voltage and then processing a DC-DC conversion, or by directly receiving a DC voltage from a battery and processing a DC-DC conversion. After processing the DC-DC conversion, the power supply circuit 110 outputs the DC operation voltages to the control unit 130. In the illustrated embodiment, the power supply circuit 110 supplies only one required DC operation voltage to the control unit 130.
The control unit 130 includes N control sub circuits 131, where N is the same number as the number N of function circuits 200. Each control sub circuit 131 includes an input terminal 1311 connected to the power supply circuit 110 for receiving a corresponding operation voltage, and a voltage output terminal 1313 connected to a respective one of the function circuits 200 to enable the corresponding function circuit 200. The control sub circuit 131 is also configured to control a starting time that the corresponding function circuit 200 receives the operation voltage. The starting time is set by controlling (i.e., selecting) a charging characteristic (i.e., rate) of a first capacitor C1 (see
Referring to
The timing circuit 133 is connected between the input terminal 1311 and ground, and includes a first resistor R1 and the first capacitor C1. The first resistor R1 and the first capacitor C1 are connected in series between the input terminal 1311 and ground. A node P1 between the first resistor R1 and the first capacitor C1 serves as a control signal output terminal 1331. When the operation voltage is input to the input terminal 1311, the first capacitor C1 is gradually charged by the operation voltage until a voltage of the first capacitor C1 has increased to a predetermined threshold value. Thereupon, the timing circuit 133 generates a control signal, and transmits the control signal to the testing circuit 135 via the control signal output terminal 1331. On the other hand, when the first capacitor C1 gradually discharges electricity until the voltage of the first capacitor C1 has decreased below the predetermined threshold value, the timing circuit 133 stops generating the control signal. In a case that the function circuit 200 requires a different starting time, a capacitance value of the first capacitor C1 and a resistance value of the first resistor R1 can be properly set accordingly.
The testing circuit 135 tests whether it is receiving the control signal by testing the voltage of the first capacitor C1. When the testing circuit 135 receives the control signal, the testing circuit 135 produces a switching-on signal and transmits the switching-on signal to the switch circuit 137. The testing circuit 135 includes a testing terminal 1351 connected to the control signal output terminal 1331, a signal input terminal 1352 connected to a ground terminal, and a signal output terminal 1353 outputting the switching-on signal to the switch circuit 137. In the embodiment, the testing circuit 135 is an n type transistor T1 which provides a low level signal (e.g. a ground signal) as the switching-on signal. Gate, emitting and base electrodes of the transistor T1 respectively serve as the testing terminal 1351, the signal input terminal 1352 and the signal output terminal 1353. The ground terminal connected to the signal input terminal 1352 functions as a signal generator, and is used to generate a ground signal which is subsequently output by the signal output terminal 1353 as the low level switching-on signal.
The switch circuit 137 is connected between the input terminal 1311 and the voltage output terminal 1313, and is configured to control whether the operation voltage is applied to the corresponding function circuit 200. In detail, when the switch circuit 137 is turned on under control of the switching-on signal, the operation voltage is transmitted to the function circuit 200 via the switch circuit 137, thereby enabling the function circuit 200 to work. Otherwise, the switch circuit 137 is turned off and the operation voltage is not transmitted to the function circuit 200. The switch circuit 137 can be for example a transistor Q1, or another suitable switch element, and has a control electrode 1371 connected to the signal output terminal 1353. In the embodiment, the switch circuit 137 is a transistor Q1. More particularly, the transistor Q1 is a p type transistor. Even more particularly, the p type transistor is a metal oxide semiconductor (MOS) transistor, that is, a P channel metal oxide semiconductor (PMOS) transistor. A gate electrode of the transistor Q1 serves as the control electrode 1371, a source electrode of the transistor Q1 is connected to the input terminal 1311, and a drain electrode of the transistor Q1 is connected to the voltage output terminal 1313.
Alternatively, the transistor Q1 is an n type transistor. More particularly, the n type transistor is a metal oxide semiconductor (MOS) transistor, that is, an N channel metal oxide semiconductor (NMOS) transistor. In such case, a signal generator (not shown) is used to generate a high level signal as the switching-on signal. The signal generator is connected to the signal input terminal 1352 of the testing circuit 135 (instead of the signal input terminal 1352 being connected to ground). The high level signal generated by the signal generator is input to the signal input terminal 1352, and is subsequently output by the signal output terminal 1353 of the testing circuit 135 to the switch circuit 137.
The protection circuit 140 acts as an overvoltage protector or an overcurrent protector, to protect the testing circuit 135 and the switch circuit 137. In the embodiment, the protection circuit 140 includes third, fourth and fifth resistors R3, R4 and R5 connected in series between the input terminal 1311 and the signal output terminal 1353 of the testing circuit 135.
During a time period after the input terminal 1311 stops receiving the operation voltage and before the voltage of the first capacitor C1 has decreased below the predetermined threshold value due to electricity discharge, the testing circuit 135 continues to output the switching-on signal and thereby maintains the switch circuit 137 in the switched-on state. Therefore, any residual electrical charges of the function circuit 200 can be discharged to ground via the switch circuit 137, the protection circuit 140 and the testing circuit 135. That is, the protection circuit 140 cooperates with the switched-on switch circuit 137 and the testing circuit 135 to form a first discharging circuit.
In this embodiment, the control sub circuit 131 can further include a second discharging circuit 138 connected between the voltage output terminal 1313 and ground. After the power supply circuit 110 stops working, any residual electrical charges of the function circuit 200 can also be discharged to ground via the second discharging circuit 138, thereby assisting the first discharging circuit to more quickly discharge the residual electrical charges of the function circuit 200. In the embodiment, the second discharging circuit 138 can be for example a second resistor R2.
In the embodiment, a second timing circuit 136 is provided in the control sub circuit 131. The second timing circuit 136 is connected between the input terminal 1311 and the signal output terminal 1353 of the testing circuit 135, and is configured to control an ending time for the supply of the operation voltage to the function circuit 200. The second timing circuit 136 includes a second capacitor C2, one end of which is connected to the input terminal 1311, and the other end of which is connected to the signal output terminal 1353 via the fifth resistor R5. The ending time can be set by controlling (i.e., selecting) a discharging characteristic (i.e., rate) of the second capacitor C2. Preferably, a time period of the discharging of the first capacitor C1 is greater than a time period of the discharging of the second capacitor C2.
In detail, when the operation voltage is applied to the input terminal 1131 and the testing circuit 135 is switched on, the second capacitor C2 is charged by the received operation voltage. During a time period after the input terminal 1311 stops receiving the operation voltage and the switch circuit 137 remains turned on, the second capacitor C2 discharges electricity to power the function circuit 200 via the switched-on switch circuit 137. A capacitance value of the second capacitor C2 and resistance values of the third and fourth resistors R3 and R4 can be properly set to achieve a desired time period of discharging of the second capacitor C2. Therefore, a desired ending time for the supply of the operation voltage to the function circuit 200 can be set easily.
Operation principles of the control sub circuit 131 are briefly described below:
When the control sub circuit 131 receives the operation voltage via the input terminal 1311, the operation voltage charges the first capacitor C1 to raise the voltage of the first capacitor C1, so that eventually the control signal output terminal 1331 of the timing circuit 133 outputs the control signal to the testing circuit 135. When the testing circuit 135 receives the control signal, the testing circuit 135 produces the switching-on signal to turn on the switch circuit 137. The function circuit 200 accordingly starts to receive the operation voltage via the switched-on switch circuit 137. The starting time that the function circuit 200 starts to receive the operation voltage can be set by properly choosing the capacitance value of the first capacitor C1 and the resistance value of the first resistor R1. At the same time, the second capacitor C2 is also charged by the received operation voltage.
When the input terminal 1311 stops receiving the operation voltage, the first capacitor C1 starts to discharge electricity to maintain the output of the control signal. Thus, the testing circuit 135 continues to output the switching-on signal to keep the switch circuit 137 turned on. At the same time, the second capacitor C2 discharges electricity to maintain the supply of power (i.e., the operation voltage) to the function circuit 200 via the switched-on switch circuit 137. The ending time for the supply of the operation voltage to the function circuit 200 can be set by properly choosing the capacitance value of the second capacitor C2 and the resistance values of the third and fourth resistors R3 and R4. After finishing the discharging of the second capacitor C2, any residual electrical charges of the function circuit 200 are able to not only be discharged to ground via the second discharging circuit 138, but also be discharged to ground via the first discharging circuit formed by the switched-on switch circuit 137, the protection circuit 140 and the testing circuit 135.
According to the above, each control sub circuit 131 in the control unit 130 can have a particular starting time of powering on the corresponding function circuit 200 set, by controlling the charging characteristic of the first capacitor C1. Therefore, the N function circuits 200 can have desired different starting times. Furthermore, a particular ending time of powering off each function circuit 200 can be set by controlling the discharging characteristic of the second capacitor C2 of the corresponding control sub circuit 131. The power supply system 100 is capable of not only providing the required operation voltage(s) to the corresponding function circuits 200, but also providing timing control to control the powering on and powering off of the function circuits 200 individually, as required.
It is to be understood, however, that even though numerous characteristics and advantages of the present embodiments have been set out in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only; and that changes may be made in detail, especially in matters of size and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201110176625.X | Jun 2011 | CN | national |
