JP2009005524A - Power supply device, and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply device that is excellent in responsiveness to current changes of a load circuit. <P>SOLUTION: Information for equipment operation is received from a system control part of equipment connected to a power supply device so as to set it in a voltage setting part as setting information. A voltage set by the voltage setting part is controlled according to the operating state of the connected equipment. Consequently, it is possible to provide a power supply device capable of supplying a stable output DC voltage. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power supply apparatus that switches an input voltage and outputs it to a connected device and an electronic device that can output an operation state.

  Conventionally, for example, a voltage drop circuit composed of a transistor as a voltage control element is provided between an input terminal to which an input DC voltage is applied and a load circuit of the device, and the voltage drop amount in the voltage drop circuit is controlled. A series control type power supply circuit that obtains a desired output DC voltage is known.

  On the other hand, the input DC voltage is controlled to ON / OFF, the input DC voltage is pulsed, the time width of the pulsed input DC voltage is controlled, and the obtained pulse voltage waveform is smoothed to obtain the desired output. A switching power supply circuit that obtains a DC voltage is also known. (For example, see Patent Document 1)

  2. Description of the Related Art In recent years, an imaging device such as a digital camera that records and reproduces still images and moving images captured by a solid-state imaging device such as a CCD sensor using a memory card having a solid-state semiconductor memory device as a recording medium has become widespread.

  Along with this, there is an increasing need for downsizing of imaging devices including power supply circuits. These imaging devices usually require a power supply circuit having a plurality of output DC voltages. From the viewpoint of miniaturization of the imaging device, a stabilized power circuit composed of a series control type power circuit that can be easily miniaturized by integration (IC) has been mainly used.

  However, in recent years, the voltage (operating voltage) applied to CPUs and DSPs (Digital Signal Processors) mounted on these image pickup devices tends to be lower. In the above-described conventional method, a low operating voltage is generated and supplied by a series control type, that is, a voltage drop type stabilized power supply circuit.

However, in this case, the power loss in the voltage control element increases due to the relationship with the output DC voltage of the battery as the voltage source, the power efficiency is significantly reduced, and the amount of heat generated in the integrated circuit including the power supply circuit increases. For this reason, instead of the series control type power supply circuit, an efficient switching type power supply circuit tends to be frequently used.
Japanese Patent Laid-Open No. 9-47023

  However, in these switching type power supply circuits, generally, an input DC voltage or an output DC voltage is detected, and control to make the output DC voltage constant is performed. However, the response is insufficient because the follow-up is after detecting a change in the voltage of the load circuit due to a change in the input DC voltage or a change in the current in the load circuit. In particular, fluctuations in the output DC voltage that occur when a sudden increase in the current of the load circuit occurs can be a problem.

  For example, in the case of a digital camera, when attention is paid to a horizontal transfer pulse signal driving circuit necessary for reading signal charges of a CCD sensor as a load circuit, reading and non-reading of signal charges are performed in the HD pulse signal cycle which is a horizontal synchronization signal. (Blanking) is repeated.

  A sudden change in the current as the load circuit in the pulse signal drive circuit here causes a sag in the output DC voltage, and this influence may cause a sag in the horizontal direction in the image signal output from the imaging device. is there. In order to prevent this, using a large capacitor at the output stage of the power supply circuit is contrary to the desired direction of downsizing the power supply circuit.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a power supply device that has good followability to a change in current of a load circuit and is suitable for downsizing.

In order to achieve the above object, a power supply device according to an embodiment of the present application is a power supply device that switches an input voltage and outputs it to a connected device, and detects the input voltage and responds to the detected result. A voltage detection means for outputting the first signal, a communication control means for communicating with the connected device and acquiring information related to the operating state of the connected device, and an output voltage based on the operating state of the electronic device. Voltage setting means for outputting a second signal related to the set output voltage, control signal generating means for outputting a third signal based on the first and second signals,
Switching means for switching the input voltage based on the third signal.

  In order to achieve the above object, an electronic device according to another embodiment of the present application is an electronic device that can output an operation state, detects an input voltage, and outputs a first signal corresponding to the detected result. Based on the first and second signals, voltage detection means for outputting, voltage setting means for setting an output voltage based on the operating state of the electronic device, and outputting a second signal related to the set output voltage Control signal generating means for outputting a third signal, and switching means for switching the input voltage based on the third signal.

  According to the present invention, it is possible to provide a power supply device that has good followability to a change in current of a load circuit and is suitable for downsizing.

<Embodiment 1>
FIG. 1 is a block diagram showing a configuration of a main part of the power supply device according to the first embodiment of the present invention. In the figure, the power supply apparatus 100 includes a voltage detection unit 110, a voltage setting unit 120, a control signal generation unit 130, a switching unit 140, a smoothing unit 150, and a communication control unit 160.

  As will be described later, a DC power source such as a battery is connected to the input terminals T1 and T2 of the power supply apparatus 100, and an input DC voltage Vin is applied thereto. Further, an output DC voltage Vout is obtained at the output terminals T3 and T4 of the smoothing unit 150, and a load circuit composed of, for example, an analog circuit or a digital circuit of a digital camera is connected thereto.

  The voltage detection unit 110 detects the input DC voltage Vin applied to the input terminals T1 and T2 (for example, the output DC voltage of a storage battery such as a lithium ion mounted on the power supply device 100). Input to the / D converter 111.

  The A / D converter 111 generates a predetermined signal according to the input DC voltage Vin input and the reference voltage Vr from the reference voltage generator 112, and a signal representative of the input DC voltage Vin is the first. A signal is output to the control signal generator 130.

  The voltage setting unit 120 includes a setting unit 121 and a storage unit 122 for setting an output voltage value of the power supply device 100 in order to output a desired output DC voltage from the output terminals T3 and T4 of the power supply device 100. A second signal is generated.

  In addition, the control signal generation unit 130 has a duty ratio corresponding to the second signal corresponding to the value of the output DC voltage set by the voltage setting unit 120 and the first signal from the voltage detection unit 110. Is generated. This is a control pulse signal and is output to the switching unit 140 as a third signal.

  The switching unit 140 includes switching elements 141 and 142 such as field effect transistors (FETs), for example. Then, the switching elements 141 and 142 are driven by the control pulse signal which is the third signal from the control signal generator 130, and the input DC voltage Vin applied between the terminals P1 and P2 is switched.

  The signal after switching is input to the smoothing unit 150 and smoothed by the smoothing coil (output inductor) 151 and the output capacitor 152. The voltage obtained by smoothing is stably supplied as an output DC voltage from the output terminals T3 and T4 to a load circuit (not shown).

  The communication control unit 160 is, for example, a device (not shown) to which the power supply apparatus 100 is connected. In this example, the communication control unit 160 is a digital camera, but the operation information from the system control unit that knows the fluctuation timing of the load circuit of the digital camera The setting unit 120 is always supplied.

  Hereinafter, operations of the power supply apparatus 100 according to the embodiment of the present invention including the above-described components will be described.

  The voltage detection unit 110 includes the A / D conversion unit 111 and the reference voltage generation unit 112 as described above. Here, when the input DC voltage applied between the input terminals T1 and T2 is Vin, the voltage detection unit 110 outputs the first signal as a digital signal having a value representative of the input DC voltage Vin. . A specific circuit configuration for that purpose will be described later.

  Thus, the voltage detection unit 110 converts the input analog input DC voltage Vin into a digital signal by the A / D conversion unit 111. Furthermore, a predetermined constant is stored in the memory built therein as information, and an operation for multiplying the digitally converted signal by the constant value as described above is performed to obtain an AA value that is the value of the first signal. Output.

Therefore, the voltage detection unit 110 includes an A / D conversion unit 111 and a reference voltage generation unit 112 as illustrated in FIG. That is, the A / D conversion unit 111 calculates the input DC voltage Vin and the reference voltage Vr generated by the reference voltage generation unit 112 from
AA = FF × (Vin / Vr) (1)
A digital signal which is the first signal indicated by is output. Here, FF is a constant value, and can take a maximum value represented by 256 bits, for example. The first signal having the AA value is then input to the control signal generator 130.

  On the other hand, when the output DC voltage of the power supply apparatus 100 is Vout, the output DC voltage Vout is set based on operation information from the communication control unit 160. The setting of the output DC voltage Vout is set by the setting unit 121 of the voltage setting unit 120 including the setting unit 121 and the storage unit 122. The set value of the output DC voltage Vout set by the setting unit 121 is stored in the form of updating the storage unit 122.

  The storage unit 122 stores the updated setting value as digital data. And although the memory | storage part 122 has memorize | stored the standard value regarding the operation | movement of the power supply device 100 from the first, digital data which is the setting value updated and memorize | stored as a 2nd signal which has XX value as The data is output to the control signal generator 130 at a predetermined clock rate.

From the first signal that is the AA value from the voltage detection unit 110 and the second signal that is the XX value from the voltage setting unit 120, the control signal generation unit 130, for example,
Dt = XX / AA (2)
A third signal, which is a control pulse signal having a pulse train (PWM modulated) waveform with a duty ratio represented by Here, the duty ratio Dt of the third signal, which is the control pulse signal, is the first signal having the AA value and the second signal having the XX value,
Dt = Vout / Vin (3)
It has been adjusted to be in the relationship. For this purpose, the XX value of the second signal is not more than the AA value of the first signal, and
XX = AA × Vout / Vin
It is necessary to satisfy the conditions.

According to the power supply apparatus 100 shown in FIG. 1, the average value of the PWM waveform from the switching unit 140 is smoothed to the output DC voltage Vout at the output of the smoothing unit 150. Therefore, from the above equations (2) and (3),
Vout = Vin × Dt = Vin × (XX / AA) (4)
When the above equation (1) is substituted into the equation (4), the output DC voltage Vout is
Vout = XX × Vr / FF (5)
It is represented by

  According to the equation (5) thus obtained, the output DC voltage Vout is stored in the storage unit 122 related to the reference voltages Vr and FF which are constants and the set voltage based on the operation information regarding the operation. It becomes a constant value determined only by the value, that is, the XX value as the second signal. That is, it is understood that the output DC voltage Vout of the power supply device 100 can be a stable output DC voltage Vout regardless of the input DC voltage Vin.

  FIG. 2 is a block diagram illustrating an example of a detailed circuit configuration of the power supply apparatus 100 according to the embodiment of the present invention. The part corresponding to FIG. 1 is shown schematically. FIG. 3 is a timing chart showing signal waveforms in main parts of the detailed circuit configuration of the power supply apparatus 100 shown in FIG. Since the basic operation has been described with reference to FIG. 1, circuit portions having the same functions are denoted by the same reference numerals, and the description of the configuration of FIG. 2 is simplified.

  An input DC voltage (for example, the output DC voltage of the battery 201) Vin is applied to the terminal Vin of the A / D converter 111 shown in FIG. 2, and at the same time, the reference voltage input terminal Vref is connected to the reference voltage generator 112. The generated reference voltage Vr is applied.

  The A / D conversion unit 111 constantly detects the input DC voltage Vin with respect to the reference voltage Vr, converts a value corresponding to the result into 8-bit digital signals B1 to B8, and outputs the digital signals. This signal is input to the input terminals A to H of the counter (CNT1) 202 at the next stage as the AA value that is the value of the first signal.

  On the other hand, the setting data set by the setting unit 121 according to the set value of the output DC voltage Vout based on the operation information from the communication control unit 160 is input to the input terminals A to H of the register of the storage unit 122. This data is setting data for obtaining a desired output DC voltage Vout from the power supply device 100. As the XX value that is the value of the second signal described above, the following data is output from the register output terminals Q1 to Q8 of the storage unit 122. Input to the input terminals A to H of the stage counter (CNT2) 203.

  The counter (CNT1) 202 and the counter (CNT2) 203 are presettable down counters. The counter 202 receives the AA value output from the A / D conversion unit 111, and the counter 203 receives the XX value set data from the storage unit 122 in synchronization with the timeout of the counter 202. Preset.

  That is, in FIG. 3, as indicated by the waveform CNT1, the count value of the counter (CNT1) 202 becomes zero. Along with this, when the waveform B, which is the output of the flip-flop (FF1) 204, becomes logic 0, the Q output of the FF2 (205) becomes logic 0 in synchronization with the rising of the waveform CLK of the next clock (at this time) The inverted output of Q is of course a logic one). Therefore, the output of the AND circuit 206 having the clock waveform CLK input to one terminal and the inverted output from the FF2 received at the other terminal changes from logic 0 to logic 1 as shown by the waveform D in FIG. To do.

  The output terminal of the AND circuit 206 is connected to the load terminals of the counter (CNT1) 202 and the counter (CNT2) 203. Therefore, in these counters 202 and 203, the AA value and the XX value are preset in synchronization with the rise of the output pulse of the AND circuit 206 described above (see waveforms CNT1 and CNT2 in FIG. 3).

  After the above presetting, both the counter (CNT1) 202 and the counter (CNT2) 203 are down-counted for each set value (preset value) according to the input clock. When the count value becomes 0, the outputs of the 8-input NOR circuits 207 and 208 connected to the output terminals (B1 to B8) of the respective counters 202 and 203 become logic 1.

  As described above, when the outputs of the NOR circuits 207 and 208 become logic 1, the FFs 204 and 209 are reset, and the counting operations in the counters 202 and 203 are also stopped. Usually, since the above-described duty ratio Dt is Dt <1, XX <AA in the normal operation state from the above equation (2). Therefore, as shown in FIG. 3, the counter (CNT2) 203 stops counting earlier than the counter (CNT1) 202.

  As described above, in the power supply apparatus 100, the counter (CNT1) 202 and the counter (CNT2) 203 are preset in synchronization with the timeout of the counter (CNT1) 202. When the count value becomes 0, the preset operation is repeated again at the next clock. Therefore, the count cycle in the counter (CNT1) 202 has a length proportional to the AA value, and the count cycle in the counter (CNT2) 203 has a length proportional to the XX value.

  Here, focusing on the waveform at point E in FIG. 2 (see waveform E in FIG. 3), during the period when the counter (CNT2) 203 counts down the set XX value, the waveform at point E is logical 1 It has become. Then, after the countdown is finished, the logic becomes 0, and again becomes the logic 1 in synchronization with the rise of the output pulse of the AND circuit 206 described above. That is, the waveform at point E has its repetition period determined by the AA value, and its duty ratio determined by XX / AA.

  Therefore, in the power supply apparatus 100, the waveform at the point E is guided to the switching elements 141 and 142 via the buffer 210 as a PWM waveform, that is, a control pulse signal as a third signal, and the switching elements 141 and 142 are controlled. Used as a drive signal.

  The switching elements 141 and 142 are two MOS-FETs (field effect transistors) having different channel types. For example, the switching element 141 is a p-channel MOS and the switching element 142 is an n-channel MOS.

  As shown in FIG. 2, the switching elements 141 and 142 have their gates connected to each other, and a control pulse signal for driving is supplied from the buffer 210 to the connection point. Further, the source of the switching element 141 is directly connected to the + terminal of the battery 201 as a power supply source, and the source side of the switching element 142 is connected to the ground side of the power supply apparatus (the minus terminal of the battery 201). ing. A connection point between the drains of the switching elements 141 and 142 of the switching unit 140 is connected to the output inductor 151 of the smoothing unit 150.

  FIG. 4 shows a driving waveform (a waveform applied to the gate) supplied to the two switching elements 141 and 142 via the buffer 210 and a waveform of a current flowing through the switching elements 141 and 142. FIG. 4A schematically shows a signal waveform of a pulse train of a third signal that is a control pulse signal applied to the gates of the switching elements 141 and 142, and the duty ratio XX / AA described above, It has a waveform that repeats ON / OFF. When one of the switching elements 141 and 142 is in the ON state, the other is in the OFF state.

  That is, when a logic 1 pulse is applied to the gate, the switching element 142 is turned on and the switching element 141 is turned off. When the gate voltage is logic 0, the opposite is true. 4B shows a current i1 flowing through the switching element 141, and a current i2 shown in FIG. 4C flows through the switching element 142. FIG.

  In this way, the two switching elements 141 and 142 perform a switching operation. Thus, the input DC voltage Vin applied between the input terminals T1 and T2 is input to the smoothing unit 150 as a pulse waveform voltage having a duty ratio of a pulse train output from the control signal generation unit 130. The smoothing unit 150 includes an output inductor 151 and an output capacitor 152, and the switching element 142 functions to release energy accumulated in the output inductor 151 when the switching element 141 is OFF.

  A control method of the power supply apparatus 100 according to the present invention configured as described above will be described with reference to FIGS. Also in FIG. 5, the same reference numerals are given to portions showing the same functions.

  As shown in FIG. 5, the DC power supply 201 connected to the input terminals T1 and T2 of the power supply apparatus 100 is equivalently represented by a circuit in which a DC voltage source 502 and an output resistance (internal resistance) 503 are connected in series. be able to. Assume that the load circuit 510 that is a digital camera connected to the output terminals T3 and T4 of the power supply apparatus 100 is, for example, a horizontal transfer pulse signal drive circuit. In this case, an abrupt change occurs in the driving current between signal charge reading and non-reading (blanking) in the HD pulse signal cycle which is a horizontal synchronizing signal.

  In this case, it is assumed that the load circuit current Iout suddenly changes from Io1 to Io2 at time T1, as shown in FIG. FIG. 6A shows an HD pulse signal (HD) and a blanking signal (PBLK). On the DC power supply 201 side, the output current Iin increases to follow the current change, and accordingly, a voltage drop due to the internal resistance (internal resistance) 503 of the DC power supply 201 occurs.

  The state at that time is shown in FIG. That is, as the current of the load circuit 510 changes from Io1 to Io2, the input DC voltage Vin drops from Vi1 to Vi2. Thereby, the output AA value of the voltage detection unit 110 described in the above formulas (1) to (5) is lowered in advance from AA1 to AA2, for example. It is assumed that this is known in advance.

  In such a case, in order to make the output DC voltage Vout constant before this fluctuation, it is understood that the XX value of the second signal that is the output of the voltage setting unit 120 needs to be increased from XX1 to XX2, for example. .

  Here, the system control unit 520 of the digital camera knows the generation timing of the load circuit 510 change that occurs in the cycle of the HD pulse signal that is the horizontal synchronization signal. The power supply apparatus 100 that can receive the information can change the XX value that is the output of the voltage setting unit 120 from, for example, XX1 to XX2 at the occurrence timing of the change of the load circuit 510.

  As described above, based on the operation information of the system control unit 520 that knows the fluctuation timing of the load circuit 510 of the device connected to the power supply apparatus 100, the setting value related to the output DC voltage Vout is set to the occurrence of the change of the load circuit 510. Change at the timing. Thereby, the output DC voltage Vout can be set to a stable value with good responsiveness to a sudden change in the output current. This eliminates the need for a large-capacitance capacitor to cope with a sudden change in output current, and as a result, the power supply device can be easily downsized.

  Note that, for example, data of XX1 and XX2, which are output XX values of the voltage setting unit 120, are acquired in advance and held by the system control unit 520, and at the occurrence timing of the load circuit 510 change, The data is transmitted to the communication control unit 160. The first signal output from the voltage detection unit 110 is transmitted to the system control unit 520 via the communication control unit 160. Thereby, for example, the data in the storage unit 122 can be acquired and updated when the device is activated or during operation.

  Further, if the storage unit 122 of the power supply apparatus 100 is further provided with a part for storing, for example, XX1 value and XX2 value, the complicated communication control unit 160 becomes unnecessary. In this case, it is only necessary to receive only the change timing signal of the load circuit 510 from the system control unit 520 as the setting information by simple communication. Also in this case, the first signal output from the voltage detection unit 110 and the second signal stored in the storage unit 122 can be acquired and updated, for example, when the device is activated or in operation. It becomes.

  Furthermore, in this embodiment, the case where the setting value related to the power supply operation is a setting value related to the output DC voltage has been described. However, as the information related to the power supply operation, the setting value related to the responsiveness of the load circuit is used. It may be. Specifically, by changing the transfer function at the timing of occurrence of a change in the load circuit, it is possible to obtain a stable value with good response to a sudden change in output current.

  According to the present invention described above, it is possible to provide a power supply apparatus that can always supply a stable output DC voltage by controlling according to the operating state of the load circuit.

  The present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the present invention. For example, in the above embodiment, a digital counter circuit is used for a control logic circuit or the like that processes an input digital signal. However, instead of these, a predetermined calculation is executed using a microprocessor, a digital signal processor (DSP) or the like, and a pulse waveform (switching waveform) with a duty ratio XX / AA is equivalently generated. Good.

  The present invention can also be implemented by supplying a storage medium storing software program codes for realizing the functions of the above-described embodiments to a system or apparatus. That is, the object of the present invention can also be achieved by reading and executing a program code stored in a storage medium by a computer (or CPU or MPU) of the system or apparatus.

  In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. As a storage medium for supplying the program code, for example, a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

  Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an OS or the like running on the computer performs actual processing based on an instruction of the program code. Some or all may be done. Thus, the present invention includes a case where the functions of the above-described embodiments are realized by the processing.

  Furthermore, in the present invention, the program code read from the storage medium can be written in a memory provided in a function expansion board inserted in the computer or a function expansion unit connected to the computer. Therefore, the function of the above-described embodiment is realized by performing part or all of the actual processing by the CPU provided in the function expansion board or function expansion unit based on the written program code instruction. Is also included.

It is a block diagram which shows schematic structure of the principal part of the power supply device which concerns on embodiment of this invention. It is an example block diagram which shows the detailed circuit structure of the power supply device which concerns on embodiment of this invention. FIG. 3 is a timing chart showing signal waveforms for explaining operations in main parts of a detailed circuit configuration of the power supply device shown in FIG. 2. It is a figure which shows the drive waveform and current waveform which are supplied to the switching element used with the detailed circuit structure of the power supply device shown in FIG. It is a figure for demonstrating operation | movement of the power supply device which concerns on embodiment of this invention. 6 is a timing chart showing signal waveforms for explaining the operation of the power supply device according to the embodiment of the present invention shown in FIG. 5.

Explanation of symbols

110 voltage detection unit 111 A / D conversion unit 112 reference voltage generation unit 120 voltage setting unit 121 setting unit 122 storage unit 130 control signal generation unit 140 switching units 141 and 142 switching element 150 smoothing unit 151 smoothing coil 152 output capacitor 160 communication control Unit 201 DC power supply 210 Buffer 502 DC voltage source 503 Output resistance (internal resistance)
510 Load circuit 520 System control unit

Claims (6)

A power supply device that switches input voltage and outputs it to connected devices,
Voltage detecting means for detecting the input voltage and outputting a first signal corresponding to the detected result;
Communication control means for communicating with a connected device and acquiring information related to the operating state of the connected device;
Voltage setting means for setting an output voltage based on an operating state of the electronic device and outputting a second signal related to the set output voltage;
Control signal generating means for outputting a third signal based on the first and second signals;
And a switching means for switching the input voltage based on the third signal.   The power supply apparatus according to claim 1, wherein the communication control unit acquires information related to an operation state of a device connected when the connected device is activated.   The power supply apparatus according to claim 1, wherein the communication control unit acquires information related to an operation state of a connected device during operation of the connected device.   4. The power supply device according to claim 1, wherein the voltage setting unit includes a storage unit that stores a second signal related to the set output voltage. 5. An electronic device capable of outputting an operating state,
Voltage detecting means for detecting an input voltage and outputting a first signal according to the detected result;
Voltage setting means for setting an output voltage based on an operating state of the electronic device and outputting a second signal related to the set output voltage;
Control signal generating means for outputting a third signal based on the first and second signals;
An electronic apparatus comprising: switching means for switching the input voltage based on the third signal.   The electronic apparatus according to claim 5, wherein the voltage setting unit includes a storage unit that stores a second signal related to the set output voltage.

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