JP2009011065A - Electronic apparatus, and switching power supply - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic apparatus which can set output voltage low without falling below a minimum driving voltage, and to provide a switching power supply to be used for an electronic apparatus. <P>SOLUTION: The electronic apparatus detects an output voltage output to a load 2 from the switching power supply which outputs output voltage on the basis of a set reference voltage via an output voltage detecting means. When the detected output voltage becomes lower than a specified voltage, a voltage higher than the reference voltage set by a control means is set as the reference voltage. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electronic device, and more particularly to an electronic device that uses a switching power supply as its power source.

The conventional switching power supply rectifies and smoothes the alternating current power supply voltage input from the input terminal into a direct current voltage, and switches the obtained direct current voltage to the alternating current voltage with a pulse width controlled at a high frequency. Convert. After the AC voltage is converted into a voltage by a high frequency transformer, the output voltage is supplied to the load terminal by rectifying and smoothing the DC voltage. At this time, a reference voltage serving as a reference is set, and the switching element is controlled so that the reference voltage matches the output voltage. The configuration of such a switching power supply is described in JP-A-9-47023.
Japanese Patent Laid-Open No. 9-47023

  However, in the conventional switching power supply, only a single output voltage is generated, and the output voltage cannot be changed according to the load condition. For this reason, it is necessary to set a higher output voltage with a sufficient margin than the minimum drive voltage so that the load does not fall below the minimum drive voltage even if load fluctuations occur in the electronic device, and power consumption cannot be reduced sufficiently. .

  Accordingly, the present invention has been made to solve such a problem, and an object of the present invention is to provide an electronic device capable of setting the output voltage low without falling below the minimum driving voltage, and a switching power supply used for the electronic device. Is to provide.

  The electronic device of the present invention is an electronic device having a switching power supply that outputs an output voltage with reference to a set reference voltage, and that detects an output voltage output from the switching power supply to a load of the electronic device. A voltage detection unit; and a control unit configured to set a voltage higher than a set reference voltage as a reference voltage when the output voltage detected by the output voltage detection unit is equal to or lower than a predetermined voltage. Yes.

  According to the present invention, it is possible to reduce the power consumption by setting the output voltage low without falling below the minimum drive voltage.

(First embodiment)
FIG. 1 is a block diagram illustrating the configuration of a digital camera according to the first embodiment of the present invention. As shown in FIG. 1, the digital camera of this embodiment includes a battery 1 that supplies power to a power supply unit 3, a load 2 such as a sensor, and a power supply unit 3 that supplies voltage to the load 2. Furthermore, it has CPU7 which performs system control and image processing, and the operation part 8 which receives the power ON / OFF operation, operation mode switching operation, etc. from a user.

  The power supply unit 3 includes a controller IC 4 for controlling output of a stable voltage, a power inductor 5, and a smoothing capacitor 6.

  The controller IC 4 includes a logic control unit 9, a feedback control unit 10, a communication interface 11, an input A / D converter 12, and a determination unit 13. The logic control unit 9 controls the operation of the entire controller IC 4 according to the IC control signal. The feedback control unit 10 controls the output voltage so as to output the output voltage constant. The communication interface 11 receives information from the CPU 7, and the input A / D converter 12 converts the input voltage input from the battery 1 into digital data. The logic control unit 9 incorporates various protection functions. For example, a low voltage protection function (UVLO) is built in that the control operation is stopped in a predetermined order when the voltage is low using the input voltage information obtained from the input A / D converter 12. Further, a short-circuit protection function (SCP) for monitoring whether or not the load is short-circuited based on output voltage data from an output A / D 14 converter, which will be described later, and stopping the switching operation of the main switch 20 when it is determined that the load is short-circuited. Also built-in. In addition, a soft start function that controls the rise of voltage to reduce inrush current and a sequence function that controls the order of multiple outputs are also included.

The feedback control unit 10 includes an output A / D converter 14, a reference data register 15, an output data comparison unit 16, a setting data recording unit 17, a PWM signal generation unit 18, a main switch driver 19, and a main switch 20. The output A / D converter 14 converts the output voltage output to the load 2 into digital data (hereinafter referred to as output voltage data _VAD ). Since the output voltage output to the load 2 is converted, the voltage of the load 2 can be accurately detected even when a voltage drop due to load fluctuation occurs. The reference data register 15 temporarily stores reference voltage data serving as a reference for the output voltage. This reference voltage data is digital data representing the reference voltage and can be easily changed. The output data comparison unit 16 compares the output voltage data V _AD and the reference voltage data. The setting data recording unit 17 holds reference voltage data and later-described determination voltage data (hereinafter referred to as _Vth ) when the power is turned off. The PWM signal generation unit 18 generates a digital PWM signal from the output of the output data comparison unit 16. The main switch driver 19 generates a control signal to the main switch 20 according to the output of the PWM signal generation unit 18. The main switch 20 performs an on / off operation of a current flowing through the power inductor 5 in accordance with a control signal of the main switch driver 19.

The determination unit 13 includes a determination data register 21, a determination data comparison unit 22, a reference data switching unit 23, and a timer 25. The determination data register 21 temporarily stores determination voltage data _Vth for determining whether to change the reference voltage data. The determination voltage data is digital data representing a determination voltage for determining whether or not to change the reference voltage, and can be easily changed. Determining data comparison unit 22 compares the determined voltage data _{V th} output voltage data _{V AD.} The reference data switching unit 23 outputs a reference voltage flag (hereinafter referred to as F) based on the comparison result of the determination data comparison unit 22. The timer 25 measures the time after changing the setting of the reference voltage.

The communication interface 11 receives information from the CPU 7 and transmits various operation mode information set by the operation unit 8 to the logic control unit 9. Further, under the control from the CPU 7, the reference voltage data and the determination voltage data _Vth for each operation mode recorded in the setting data recording unit 17 are rewritten.

As described above, the setting data recording unit 17 stores the reference voltage data and the determination voltage data, but in this embodiment, two types of reference voltage data are stored for each operation mode. The first reference voltage data (hereinafter referred to as _VL ) is reference voltage data representing the first reference voltage, and the first reference voltage is a lower reference voltage value for low power consumption. The second reference voltage data (hereinafter referred to as V _H ) is reference voltage data representing the second reference voltage, and the second reference voltage is a higher reference in order to prevent malfunction due to a voltage drop caused by load fluctuation. It is a voltage value. The first reference voltage is set to a voltage smaller than the second reference voltage. These two types of reference voltage data are stored in different memory addresses for each operation mode, such as V _L1 / V _H1 when the operation mode is the reproduction mode and V _L2 / V _H2 when the operation mode is the shooting mode. Has been. Operation mode information and a reference voltage flag are transmitted from the logic control unit 9 to the setting data recording unit 17. For example, when the reference voltage flag is F = 0 in the reproduction mode, the first reference voltage data V _L1 is used. When the reference voltage flag is F = 1 in the shooting mode, the second reference voltage data V _H2 is used as the reference data register. Expanded to On the other hand, the determination voltage data V _th is one for each operation mode, and the determination voltage data for the reproduction mode is V _th1 and the determination voltage data for the shooting mode is V _th2. Has been. Similar to the reference voltage data, the determination voltage data _Vth corresponding to the operation mode information transmitted from the logic control unit 9 is developed in the determination data register 21.

When the power source of the digital camera is turned on and an activation control signal is received from the operation unit 8, the logic control unit 9 transmits a development control signal of reference voltage data and determination voltage data _Vth to the setting data recording unit 17. Receiving it, the setting data recording unit 17 develops each data in the reference data register 15 and the determination data register 21. Until the CPU is activated and the operation mode information can be acquired, the mode data set as default is expanded. In the present embodiment, the default mode is a shooting mode. The reference voltage data and the output voltage data V _AD converted into digital data by the output A / D converter 14 are compared by the output data comparison unit 16, and based on the result, the PWM signal generation unit 18 performs the digital PWM signal. Is generated. In accordance with the digital PWM signal, the main switch 20 is controlled to be turned on / off via the main switch driver 19 to keep the output voltage constant. When the CPU 7 is activated to establish communication and the operation mode information is transmitted to the logic control unit 9 via the communication interface 11, the logic control unit 9 sends the operation mode information and the data development control signal to the setting data recording unit 17. introduce. Based on the information, the setting data recording unit 17 develops the corresponding reference voltage data and determination voltage data _Vth in the reference data register 15 and the determination data register 21 again. Similarly, when the operation mode is switched by the user during the operation, the data corresponding to the operation mode is developed again.

Next, the flow of output voltage control when the operation mode is set to the reproduction mode in the present embodiment will be described with reference to the flowchart of FIG. The determination voltage data in the reproduction mode is V _th1 .

In ST201, the setting data recording unit 17 develops the determination voltage data _Vth1 corresponding to the reproduction mode in the determination data register 21, and proceeds to ST202. In ST202, the reference data switching unit 23 sets the reference voltage flag to F = 0, so that the setting data recording unit 17 develops the first reference voltage data V _L1 corresponding to the reproduction mode in the reference data register 15. Further, the timer 25 resets the count number (hereinafter referred to as C) to 0, and proceeds to ST203. In ST 203, converts the output voltage data _{V AD} the output voltage by the output A / D converter 14 proceeds to ST 204. In ST 204, and compares the determined voltage data _{V th1} of the reproduction mode and converted output voltage data _{V AD} in ST203 in the determination data comparison unit 22. If the output voltage data V _AD is lower than the determination voltage data V _th1 , the process _proceeds to ST205, otherwise, the process returns to ST203 and the output voltage data V _AD is converted. In ST205, the reference data switching unit 23 sets the reference voltage flag to F = 1, so that the setting data recording unit 17 develops the second reference voltage data _VH1 in the reference data register 15 to increase the output voltage. Move on to ST206. In ST 206, the process proceeds to count C to start the counting of the timer 25 When switched to the second reference voltage data _{V H1} to count up to ST207 with ST205. In ST207, the number of counts to a predetermined back to ST206 does not reach the (hereinafter referred to as _{C 0),} the flow returns to ST202 reached. ST206 and ST207, after which was a lapse of a predetermined time while set high output voltage by being switched to the second reference voltage data V _H1, an operation for returning the output voltage to the previous setting. As a result, the output voltage is automatically set so that the power consumption is lowered after the operation based on the second reference voltage data V _H1 has elapsed for a predetermined time without maintaining the state of high power consumption more than necessary. Therefore, power consumption can be reduced.

According to the present embodiment, when the output voltage data V _AD does not fall below the determination voltage data V _th , power consumption can be reduced by setting a low reference voltage. Further, when the output voltage data V _AD is lower than the determination voltage data V _th , malfunction of a connected load can be prevented by setting a high reference voltage. In other words, when the output voltage is higher than the judgment voltage, the power consumption is reduced by setting it to a low reference voltage, and when the output voltage is lower than the judgment voltage, the connected load malfunctions by setting it to a higher reference voltage. Prevent such as. In addition, by setting again to a low reference voltage after a predetermined time after setting to a high reference voltage, it is possible to maintain a high power consumption state to prevent load malfunctions more than necessary. Power consumption can be reduced.

  In the present embodiment, the flow of output voltage control when the operation mode is set to the reproduction mode has been described. However, even when the operation mode is set to an operation mode other than the reproduction mode, the first and second reference voltage data and It goes without saying that the same control is performed only by different judgment voltage data.

Further, the reference voltage data is switched depending on whether the output voltage data V _AD is lower than the determination voltage data V _th , but the reference voltage data is switched depending on whether the output voltage data V _AD is equal to or lower than the determination voltage data V _th. You may do it. That is, when the output voltage is higher than the determination voltage, the reference voltage may be set to a low reference voltage, and when the output voltage is equal to or lower than the determination voltage, the reference voltage may be set to a high reference voltage.

(Second Embodiment)
FIG. 3 is a block diagram illustrating the configuration of a digital camera embodying the present invention. In FIG. 3, the same parts as those of the first embodiment shown in FIG. The difference from the first embodiment shown in FIG. 1 is that the set voltage switching unit 23 is a reference data correction unit 24. The reference data correction unit 24 subtracts the determination voltage data (hereinafter referred to as _Vth ) from the output voltage data (hereinafter referred to as _VAD ) obtained by the output A / D converter 14 (hereinafter referred to as ΔV). The reference voltage data (hereinafter referred to as V _ref ) is corrected according to the Since the reference voltage data V _ref during operation is calculated and determined by the reference data correction unit 24, the setting data recording unit 17 stores initial reference voltage data (hereinafter referred to as V0) at the time of start-up and determination voltage data V _th. Is stored. In addition, the upper reference voltage within the range that can be set as the reference voltage is set so that the output voltage is not set so high that the load breaks or breaks due to the correction, or the output voltage is not realizable with respect to the input voltage. The maximum reference voltage data (hereinafter, referred to as V1) representing is also stored. Further, a correction coefficient (hereinafter referred to as K: K> 1) applied when a difference ΔV obtained by subtracting the determination voltage data _Vth from the output voltage data V _AD obtained by the output A / D converter 14 is lower than a threshold value. ) And its threshold value (hereinafter referred to as V2: V2 <0). The initial reference voltage data V0, the maximum reference voltage data V1, the threshold value V2, and the correction coefficient K are set to be the same regardless of each operation mode such as the reproduction mode and the photographing mode. The determination voltage data _Vth is set for each operation mode as in the first embodiment. As described above, the content of data recorded in the setting data recording unit 17 is different from that of the first embodiment.

Next, the flow of output voltage control when the operation mode is set to the reproduction mode in the present embodiment will be described with reference to the flowchart of FIG. The determination voltage data in the reproduction mode is V _th1 .

In ST 401, configuration data recording unit 17, to expand the determination voltage data _{V th1} in the reproduction mode determination data register 21, the process proceeds to ST 402. In ST 402, the timer 25 the counter number (hereinafter referred to as C) reset resets the zero, the value of the difference ΔV which reference data correcting section 24 by subtracting the determined voltage data _{V th1} from the output voltage data _{V AD} 0 To do. Further, the setting data recording unit 17 develops the initial reference voltage data V0 in the reference data register 15 as the reference voltage data _Vref , and proceeds to ST403. In ST 403, converts the output voltage data _{V AD} the output voltage by the output A / D converter 14 proceeds to ST 404. In ST 404, it calculates the difference ΔV by subtracting the determined voltage data _{V th1} from the output voltage data _{V AD} by determining data comparison unit 22 in the reproducing mode proceeds to ST 405. In ST405, it is determined whether the difference ΔV calculated in ST404 by the reference data correction unit 24 is negative, that is, whether the output voltage data V _{A / D} is smaller than the determination voltage data V _th1 in the reproduction mode. If the difference ΔV is negative, the process proceeds to ST406, and if the difference ΔV is not negative, the process proceeds to ST414. In ST406, the reference data correction unit 24 determines whether the difference ΔV is smaller than the threshold value V2. If difference ΔV is smaller than threshold value V2, the process proceeds to ST409, and if difference ΔV is greater than or equal to threshold value V2, the process proceeds to ST407. In ST407, the logic controller 9 compares the value obtained by adding the absolute value of the difference ΔV to the reference voltage data _Vref and the maximum reference voltage data V1. If the value obtained by adding the absolute value of the difference ΔV to the reference voltage data V _ref is larger than the maximum reference voltage data V1, the process proceeds to ST411, otherwise the process proceeds to ST408. In ST 408, the value obtained by adding the absolute value of the reference voltage data _{V ref} to the difference [Delta] V, setting data recording unit 17 shifts to ST403 developed in the reference data register 15 as the next reference voltage data _{V ref.} At this time, the timer 25 resets the counter number C to zero. In ST409, when it is determined in ST406 that the difference ΔV is smaller than the threshold value V2, the logic control unit 9 adds a value obtained by multiplying the absolute value of the difference ΔV by the correction coefficient K to the reference voltage data _Vref. Comparison with the maximum reference voltage data V1 is performed. If the value obtained by adding the correction coefficient K to the absolute value of the difference ΔV to the reference voltage data _Vref is greater than the maximum reference voltage data V1, the process proceeds to ST407, otherwise the process proceeds to ST410. When comparing ST407 and ST409, the method of correcting the reference voltage data _Vref is changed according to the determination result of ST406. And when the difference ΔV is greater than or equal to the threshold value V2, that is when the voltage drops is small until then acquires the output voltage data V _AD after obtaining the output voltage data V _AD. In this case, a voltage enough lower than the minimum driving voltage during a period from correcting the reference voltage data V _ref until corrected again reference voltage data V _ref is unlikely to be reduced. In ST407, therefore, the reference voltage data V _ref is corrected so that the output voltage is increased by the absolute value of the difference ΔV without performing a correction that significantly increases the output voltage in order to keep power consumption low. On the other hand, a case where the difference ΔV is smaller than the threshold value V2, that is when the voltage drops is large until then acquires the output voltage data V _AD after obtaining the output voltage data V _AD. In this case, a voltage enough lower than the minimum driving voltage during a period from correcting the reference voltage data V _ref until corrected again reference voltage data V _ref is also possible to decrease. Therefore, in ST409, the reference voltage is set so that the output voltage is sufficiently high so that the absolute value of the difference ΔV is multiplied by the correction coefficient K, that is, the output voltage is not lower than the minimum drive voltage until the next correction. The data V _ref is corrected. In ST 410, the value obtained by adding a value obtained by multiplying the correction coefficient K to the absolute value of the difference ΔV to the reference voltage data _{V ref,} the setting data storage unit 17 to expand in the reference data register 15 as the next reference voltage data _{V ref} ST 403 Migrate to At this time, the timer 25 resets the counter number C to zero. In ST411, the setting data recording unit 17 develops the maximum reference voltage data V1 as the next reference voltage data _Vref in the reference data register 15 and proceeds to ST412. At this time, the timer 25 resets the counter number C to zero. In ST412, the timer 25 starts counting, the count number C is incremented, and the process proceeds to ST413. In ST413, if it has not reached to count the number of _{C 0} the timer 25 is predetermined to return to the ST412, return to ST402 reached. ST412 and ST413 are operations for returning the output voltage to the initial setting after a predetermined time has elapsed with the output voltage set high. This is the same as ST206 and ST207 in the first embodiment. As a result, the output voltage is automatically set so that the power consumption is reduced after the operation based on the maximum reference voltage data V1 has elapsed for a predetermined time without maintaining a high power consumption state more than necessary. Can be reduced. In ST414, when it is determined in ST405 that the difference ΔV is not negative, it is determined whether the reference voltage data V _ref set by the logic control unit 9 is the initial reference voltage data V0. If the set reference voltage data V _ref is the initial reference voltage data V0, the process proceeds to ST403, and if not, the process proceeds to ST415. Whether the reference voltage data V _ref is the initial reference voltage data V0 is determined to determine whether the reference voltage data V _ref is corrected. When the reference voltage data V _ref is corrected, the output voltage is set higher than when the reference voltage data V _ref is the initial reference voltage data V 0, and therefore the same control as ST 412 and ST 413 can be performed. desirable. Therefore, similarly to ST412 and ST413, the time measurement after changing the setting of the reference voltage data _Vref is performed in ST415 and ST416. In ST415, the timer 25 starts counting, the count number C is incremented, and the process proceeds to ST416. In ST416, if it has not reached to count the number of _{C 0} the timer 25 is predetermined to return to the ST403, return to ST402 reached.

Next, changes in output voltage data when the above output voltage control is performed will be described with reference to FIGS. 5 and 6. FIG. For simplicity of explanation, the maximum reference voltage data V1 and the threshold value V2 are not provided. FIG. 5 shows output voltage data from before the voltage drop due to load fluctuation until the voltage drop ends. The output voltage data when the reference voltage data V _ref is not corrected at the time of voltage drop is V _AD, and the output voltage data when it is corrected is V ′ _AD . ΔV _a , ΔV _b , ΔV _c and ΔV _d are differences ΔV obtained by subtracting the determination voltage data _Vth from the output voltage data V ′ _AD . FIG. 6 is an enlarged view of a portion where the change in the output voltage data V ′ _AD is large in FIG. 5. t1 to t8 represent timing for sampling the output voltage data. The output voltage decreases due to the load variation, and the output voltage data V _AD becomes smaller than the determination voltage data V _{th at} t3. The difference obtained by subtracting the determination voltage data V _th from the output voltage data V ′ _{AD at} this time is ΔV _a , and a value obtained by adding the absolute value of ΔV _a to the reference voltage data V _ref to increase the output voltage is _a new value. Set as reference voltage data V _ref . At t4, output voltage data V ′ _AD that is larger than the output voltage data V _AD when not corrected by the absolute value of ΔV _a is detected. However, since the output voltage data V _AD is smaller than the determination voltage data V _th even at t4, the value obtained by adding the absolute value of the difference ΔV _{b at} this time to the reference voltage data V _ref is set as a new reference, similarly to t3. Set as voltage data V _ref . At t5, output voltage data V ′ _AD that is larger than the output voltage data V _AD that is not corrected by the sum of the absolute value of ΔV _{a and} the absolute value of ΔV _b is detected. The difference at this time is ΔV _c , and the reference voltage data V _ref is newly set in the same manner as t3 and t4. In t6, to detect the absolute value and the [Delta] V absolute value [Delta] V absolute only value amount obtained by adding a large output voltage data V _'AD of _c and _b of the [Delta] V _a than the output voltage data V _AD when no corrected. Difference at this time is [Delta] V _d, newly setting the reference voltage data _{V ref} in the same way as t3, t4 and t5. At t7, the output voltage data V ′ that is larger than the output voltage data V _AD without correction by the sum of the absolute value of ΔV _a , the absolute value of ΔV _b , the absolute value of ΔV _c , and the absolute value of ΔV _d. Detect _AD . At this time, since the output voltage data V ′ _AD is larger than the determination voltage data V _th , the setting of the reference voltage data V _ref is not changed. As shown in FIG. 5, t7 after the output voltage data V _'AD is greater condition persists than the set voltage data V _th. If the output voltage data V ′ _AD is larger than the set voltage data V _{th for a} certain period of time, it is determined that the output voltage is not likely to fall below the minimum drive voltage, and the reference voltage data V _ref is set to the initial value before correction. Change to a value.

As described above, according to the present embodiment, when the output voltage data V _AD does not fall below the determination voltage data V _th , power consumption can be reduced by setting a low reference voltage. Furthermore, if the output voltage data V _AD falls below the determination voltage data V _th is a load connected by setting a high reference voltage in response to the difference ΔV by subtracting the determined voltage data V _th from the output voltage data V _AD Malfunctions can be prevented. In addition, by setting it to a low voltage again after a predetermined time after setting it to a high reference voltage, the power consumption to prevent malfunction of the load is maintained without maintaining more than necessary. Electric power can be reduced.

  Further, by providing maximum reference voltage data V1 that serves as a limiter so that an output voltage that is high enough to cause a failure or destruction of the load by correction or an output voltage that cannot be realized with respect to the input voltage is set. The correction can prevent the output voltage from becoming too high.

  In this embodiment, the flow of output voltage control when the operation mode is set to the reproduction mode has been described. However, even when the operation mode is set to a mode other than the reproduction mode, the same control is performed only by the determination voltage data being different. Needless to say.

Further, the control flow is changed depending on whether or not the difference ΔV obtained by subtracting the determination voltage data _Vth from the output voltage data V _AD is smaller than the negative threshold value V2, but is the absolute value of the difference ΔV equal to or greater than a predetermined value? The flow of control may be changed depending on how. In addition, instead of comparing the difference ΔV with the threshold value, second determination voltage data lower than the determination voltage data is provided, and whether or not the output voltage data V _AD is lower than the second determination voltage data is compared. May be.

  In the above-described two embodiments, the configuration used for the switching power supply of the digital camera has been described.

  In addition, the output voltage is controlled using a digital signal, but may be configured using an analog signal.

  In addition, data related to output voltage control such as reference voltage data and determination voltage data is held inside the power supply. However, a means for holding these data is provided outside the power supply unit and used when controlling the output voltage. You may do it.

  Further, although the step-down configuration is taken up in the configuration diagram, the present invention is not limited to the step-down configuration, and can be applied to any power supply topology.

Moreover, it is good also as a structure which combined two above-mentioned embodiment. For example, by providing a plurality of pre-reference voltage data _{V ref,} if the output voltage data _{V AD} determination voltage data _{V th} smaller, depending on the magnitude of the difference ΔV by subtracting the determined voltage data _{V th} from the output voltage data _{V AD} The reference voltage data V _ref to be set is changed. When the absolute value of the difference ΔV is less than or equal to a predetermined value, the amount of change in voltage due to load fluctuation is expected to be small, and therefore the reference voltage is switched to a slightly higher reference voltage before load fluctuation. On the other hand, when the absolute value of the difference ΔV is larger than the predetermined value, the amount of change in the voltage due to the load fluctuation is expected to be large. . By switching the reference voltage in this way, the power consumption can be further reduced without switching to a higher reference voltage than necessary when switching.

Configuration diagram of the first embodiment The figure which shows the flow of control of 1st Embodiment. Configuration diagram of second embodiment The figure which shows the flow of control of 2nd Embodiment. Figure showing output voltage data at the time of voltage drop Enlarged view showing output voltage data at voltage drop

Explanation of symbols

1 Battery 2 Load 3 Power supply 4 Controller IC
5 Power inductor 6 Smoothing capacitor 7 CPU
DESCRIPTION OF SYMBOLS 8 Operation part 9 Logic control part 10 Feedback control part 11 Communication interface 12 Input A / D converter 13 Judgment part 14 Output A / D converter 15 Reference data register 16 Output data comparison part 17 Setting data recording part 18 PWM signal generation part 19 main switch driver 20 main switch 21 determination data register 22 determination data comparison unit 23 reference data switching unit 24 reference data correction unit 25 timer

Claims (18)

An electronic device having a switching power supply that outputs an output voltage based on a set reference voltage,
Output voltage detection means for detecting an output voltage output from the switching power supply to a load of the electronic device;
When the output voltage detected by the output voltage detection means is equal to or lower than a predetermined voltage, control means for setting a reference voltage higher than the set reference voltage;
An electronic device comprising:   The control means has a plurality of reference voltages, and switches the setting to a reference voltage higher than a reference voltage set from the plurality of reference voltages when the output voltage becomes a predetermined voltage or less. The electronic device according to claim 1. A calculation means for calculating a difference between the output voltage and the predetermined voltage;
The electronic apparatus according to claim 1, wherein the control unit sets a reference voltage according to a difference calculated by the calculation unit when the output voltage becomes equal to or lower than a predetermined voltage.   The control means sets a voltage obtained by adding the absolute value of the difference calculated by the calculation means to a reference voltage that is set when the output voltage becomes equal to or lower than a predetermined voltage. The electronic device according to claim 3.   When the output voltage is equal to or lower than a predetermined voltage and the absolute value of the difference is equal to or higher than a predetermined value, the control means uses a voltage obtained by adding a value larger than the absolute value of the difference as a reference voltage. The electronic device according to claim 4, wherein the electronic device is set.   The said control means has an upper limit reference voltage which can be set to the said reference voltage, and sets a reference voltage in the range which does not exceed the said upper limit reference voltage, The any one of Claim 3 thru | or 5 characterized by the above-mentioned. The electronic device described.   The control means has a plurality of reference voltages, and switches the reference voltage to be set according to the difference calculated by the comparison means when the output voltage becomes a predetermined voltage or less. 3. The electronic device according to 3. Having time measuring means for measuring the time since the setting of the reference voltage is changed to be high,
The control means sets a reference voltage lower than a set reference voltage when a predetermined time has elapsed after the time measurement means starts measuring time. Item 8. The electronic device according to any one of Items 7.   The electronic apparatus according to claim 1, wherein the control unit sets the reference voltage with digital data. A switching power supply that outputs an output voltage based on a set reference voltage,
Output voltage detecting means for detecting the output voltage;
When the output voltage detected by the output voltage detection means is equal to or lower than a predetermined voltage, control means for setting a reference voltage higher than the set reference voltage;
A switching power supply comprising:   The control means has a plurality of reference voltages, and switches the setting to a reference voltage higher than a reference voltage set from the plurality of reference voltages when the output voltage becomes a predetermined voltage or less. The switching power supply according to claim 10. A calculation means for calculating a difference between the output voltage and the predetermined voltage;
The switching power supply according to claim 11, wherein the control unit sets a reference voltage according to a difference calculated by the calculation unit when the output voltage becomes equal to or lower than a predetermined voltage.   13. The control unit according to claim 12, wherein when the output voltage becomes equal to or lower than a predetermined voltage, the control unit sets a voltage obtained by adding the absolute value of the difference to a set reference voltage as a reference voltage. Switching power supply.   When the output voltage is equal to or lower than a predetermined voltage and the absolute value of the difference is equal to or higher than a predetermined value, the control means uses a voltage obtained by adding a value larger than the absolute value of the difference as a reference voltage. The switching power supply according to claim 13, wherein the switching power supply is set.   15. The control unit according to claim 12, wherein the control unit has an upper limit reference voltage that can be set as the reference voltage, and sets the reference voltage in a range not exceeding the upper limit reference voltage. The switching power supply described.   The control means is provided with a plurality of reference voltages, and switches a reference voltage to be set according to a difference result calculated by the comparison means when the output voltage becomes a predetermined voltage or less. Item 13. The switching power supply according to Item 12. Having time measuring means for measuring the time since the setting of the reference voltage is changed to be high,
The control means sets a voltage lower than a set reference voltage as a reference voltage when a predetermined time has elapsed since the time measurement means started measuring time. Item 17. The switching power supply according to any one of Items 16 above.   The switching power supply according to any one of claims 10 to 17, wherein an output voltage is output with reference to reference voltage data in which the reference voltage is expressed in digital data.

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