Power supply device, method for controlling power supply device by communication, method for testing power supply device, and method for testing multiple power supply devices

Abstract

To provide a power supply device capable of controlling the power supply device by communication without being impacted by a switching power supply nor sacrificing a characteristic, and capable of subsequently outputting a desired voltage quickly.SOLUTION: A power supply device 1 according to an embodiment of the present invention comprises: switching power supply parts 11 to 14 for switching applied power to an external circuit E1; a control part 2 for controlling the switching power supply parts 11 to 14; a communication part 3 for transmitting / receiving a signal between the control part 2 and an external device M; and an input terminal 4 that accepts an input signal for giving instructions to the control part 2. The switching power supply parts 11 to 14 each comprise: an output circuit which is connected to an output terminal and which perform switching on an output current; and a switching control circuit for controlling the output circuit. The control part 2 is constituted so as to stop switching of the output circuit, while keeping causing the switching control circuit to function in response to the input signal to the input terminal 4.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power supply device, a method for reducing noise superimposed on a communication signal in a power supply device, a method for controlling a power supply device by communication, a method for testing a power supply device, and a method for testing a plurality of power supply devices. [Background technology]

[0002] Power supplies that convert input voltages to the desired output voltages are used in many electrical devices. For example, power supplies that include switching power supplies are used to efficiently convert input voltages to the desired voltage. Furthermore, hybrid power supplies, such as those containing multiple switching power supplies or those containing both a switching power supply and a low-dropout (LDO) regulator, are also used in applications requiring multiple power supplies with different specifications, such as mobile devices like smartphones, home appliances, industrial equipment like robots, and transportation equipment like automobiles. These hybrid power supplies are integrated into semiconductor devices with circuits that control the output voltages of each of the multiple power supplies, and are also offered as power management integrated circuits (PMICs).

[0003] In recent years, power supply devices such as PMICs have also been controlled via communications. For example, PMICs equipped with communications interfaces compatible with communications standards such as Inter-Integrated Circuit (I2C) and Serial Peripheral Interface (SPI) are now available.

[0004] On the other hand, in a switching power supply, the power provided from the input side to the output side is adjusted by switching the current at a frequency of, for example, several hundred kHz to several MHz. That is, in a switching power supply, the current is switched between on and off or the current direction is switched at a frequency of, for example, several MHz, and the operation of circuits around the switching power supply may be interfered with by the switching. For example, Patent Document 1 discloses that in a power supply device equipped with a receiver for receiving broadcast waves and switching the voltage from an input power supply at the transmission frequency of a transmission circuit, the transmission frequency is changed when the difference between the harmonics of the transmission frequency and the frequency of the broadcast waves is within a predetermined deviation. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Application No. 2005-130081 Summary of the Invention [Problem to be solved by the invention]

[0006] In a power supply device including a switching power supply controlled by communication, as described above, noise can occur in signals transmitted via digital communication using a communication standard such as the aforementioned SPI due to ground level fluctuations caused by switching of the switching power supply or electromagnetic waves emitted from the switching power supply. If unintended level fluctuations due to noise occur in a signal that should be transmitted according to a specific communication standard, the information contained in the signal sent from the transmitting side may not be accurately received by the receiving side. Furthermore, the transmitted signal may end up being a signal that does not comply with the communication standard and therefore cannot be received by the receiving side. This may result in the power supply device becoming uncontrollable via communication. Furthermore, the noise generated in the communication signal cannot be significantly reduced by slightly shifting the oscillation frequency of the switching power supply from a specific frequency, as disclosed in Patent Document 1. If the oscillation frequency of the switching power supply is around a few kHz, the frequency at which noise occurs in the communication signal is reduced, making it less likely to cause substantial communication problems. However, if the oscillation frequency is low, the desired characteristics of the power supply, such as efficiency, may not be achieved.

[0007] Furthermore, when testing a power supply device, such as a PMIC, that includes a switching power supply controlled by such communication, noise from the switching power supply can prevent proper communication with the PMIC, making it impossible to set or switch the PMIC to the appropriate state (mode) for the test item, or requiring a long time to set it to the appropriate state. This can result in increased PMIC test time or even a defective product being deemed defective, resulting in a reduced apparent yield. While the aforementioned communication problems may not occur if the operational test is performed at a switching frequency of a few kHz, such a test is a substitute for the actual operating state and cannot determine whether the desired characteristics are achieved under the expected operating conditions.

[0008] In view of these problems, an object of the present invention is to provide a power supply device that can be controlled via communication without being affected by a switching power supply and without sacrificing performance, and that can quickly output a desired voltage after control via communication. Another object of the present invention is to provide a method for reducing noise superimposed on communication signals in a power supply device, which allows a power supply device to be controlled via communication without being affected by a switching power supply and enables the power supply device to quickly output a desired voltage after control. Another object of the present invention is to provide a method for controlling a power supply via communication without being affected by a switching power supply, which enables the power supply device to quickly output a desired voltage after control. Another object of the present invention is to provide a power supply testing method that allows a power supply device to be controlled via communication quickly without being affected by a switching power supply during testing, thereby enabling the power supply device to be tested easily and in a short time. [Means for solving the problem]

[0009] One embodiment of the power supply device of the present invention includes one or more switching power supply units that switch power supply to an external circuit, a control unit that controls each of the one or more switching power supply units, a communication unit that transmits and receives signals between the control unit and an external device, and an input terminal that receives an input signal that provides an instruction to the control unit. A power supply device Each of the one or more switching power supply units includes an output circuit connected to an output terminal for switching an output current, and a switching control circuit for controlling the output circuit, and the control unit is configured to stop switching of the output circuit while keeping the switching control circuit functioning in response to an input signal to the input terminal. and when the switching is stopped, a signal indicating that the switching is stopped is transmitted from the communication unit to the external device, and the external device is configured to be controlled by a control signal received by the communication unit while the switching is stopped. are.

[0011] The method for controlling a power supply device by communication of the present invention is a method for controlling a power supply device by communication, which includes one or more switching power supply units and a communication unit that receives signals from an external device, and includes an output circuit that switches an output current and a switching control circuit that controls the output circuit, the switching power supply unit includes an output circuit that switches an output current and a switching control circuit that controls the output circuit, and the method includes stopping switching of the output circuit while allowing the switching control circuit to function, and controlling the power supply device by sending a control signal to the communication unit while the switching is stopped; When the switching is stopped, a signal indicating that the switching is stopped is transmitted from the communication unit to the external device. Includes.

[0012] A test method for a power supply device of the present invention is a test method for a power supply device that includes one or more switching power supply units and is controlled by communication, the test method comprising the steps of: stopping switching of the output circuit while continuing to operate the switching control circuit, of an output circuit that switches an output current and a switching control circuit that controls the output circuit, included in the switching power supply unit; switching the power supply device from a first test mode to a second test mode through the communication while the switching is stopped; The stopped switching is restarted. In the second test mode and measuring at least one characteristic of the power supply. [Effects of the Invention]

[0013] According to the power supply device of the present invention, an input terminal is provided for receiving an input signal that instructs the control unit to stop switching of the output circuit while keeping the switching control circuit of the switching power supply unit functioning, so that the power supply device can be controlled by communication without being affected by the switching power supply and without sacrificing characteristics, and yet can quickly output the desired voltage after control by communication. Also, according to the method for reducing noise superimposed on communication signals in a power supply device of the present invention, the method for controlling a power supply device by communication of the present invention, and the method for testing a power supply device of the present invention, the switching of the output circuit is stopped while keeping the switching control circuit of the switching power supply unit functioning, so that the power supply device can be controlled by communication without being affected by the switching power supply, and yet can quickly output the desired voltage after control, thereby enabling the power supply device to be tested easily and in a short time. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a block diagram showing a schematic configuration of an example of a power supply device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a block diagram showing the internal configuration of a switching power supply unit according to an embodiment of the present invention. [Figure 3] 4A and 4B are diagrams showing noise occurring in a communication signal and an output voltage of a power supply device. [Figure 4] FIG. 1 is a block diagram showing an example of use of a power supply device according to an embodiment of the present invention. [Figure 5] 4 is a flowchart showing an example of a method for testing a power supply device according to an embodiment of the present invention. [Figure 6] 4 is a timing chart showing an example of a procedure of a test method for a power supply device according to an embodiment of the present invention. [Figure 7] 4 is a timing chart showing an example of the procedure of a method for testing a plurality of power supply devices according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] <Power supply configuration> Next, an embodiment of the power supply device of the present invention will be described with reference to the drawings, but the present invention is not limited to this embodiment.

[0016] FIG. 1 shows a power supply device 1, which is an example of a power supply device according to an embodiment. External circuits E1-E4 are connected to the power supply device 1 in FIG. 1, and loads LD1-LD4 are connected to the external circuits E1-E4, respectively. An external device M is also connected to the power supply device 1 in FIG. 1. In the example of FIG. 1, the external device M is a microcomputer, which is a semiconductor integrated circuit device that controls the voltage generation and output functions of the power supply device 1, but the external device connected to the power supply device of this embodiment is not limited to a microcomputer. Furthermore, the loads LD1-LD4 may be any electronic component, combination of electronic components, electrical equipment, or electrical system that is supplied with a constant voltage and consumes the required power.

[0017] As shown in FIG. 1, power supply device 1 of this embodiment includes one or more switching power supply units (four switching power supply units 11-14 in the example of FIG. 1), a control unit 2 that controls each of the one or more switching power supply units, a communication unit 3 that transmits and receives signals between control unit 2 and external device M, and an input terminal (first input terminal) 4. Control unit 2 controls each of switching power supply units 11-14. Each of switching power supply units 11-14 switches the supply of current to external circuits E1-E4 that are connected to loads LD1-LD4, respectively. Each of switching power supply units 11-14 supplies current to or drives each of external circuits E1-E4.

[0018] 1 further includes three LDO regulators 15. Each LDO regulator 15 supplies power at a predetermined voltage to a load (not shown). Note that the power supply device of one embodiment may include any number of power supply units, one or more, including switching power supplies such as switching power supply units 11-14, and any number of power supply units including linear regulators such as LDO regulator 15.

[0019] In the power supply device 1 of Fig. 1, switching power supply units 11 to 14, a control unit 2, a communication unit 3, and three LDO regulators 15 are integrated into a single-chip semiconductor device. In other words, the power supply device 1 is an example in which the power supply device of this embodiment is embodied as a so-called power management IC (PMIC). However, the power supply device of this embodiment does not necessarily have to be integrated into a single-chip semiconductor device, and may be configured by connecting each component that is formed individually.

[0020] The switching power supply units 11 to 14 each include a driver connected to an external circuit E1 to E4, and each driver includes a switching element such as a field effect transistor (FET) that switches between a current conducting state and a current blocking state. The switching power supply unit 11 (first switching power supply unit) includes a high-side pre-driver T1 and a low-side pre-driver T2. The output nodes of the pre-driver T1 and the pre-driver T2 are respectively connected to the output terminal of the power supply device 1. The pre-driver T1 and the pre-driver T2 are configured with a switching element such as a FET.

[0021] The external circuit E1 includes a high-side main driver S1, a low-side main driver S2, a coil L1, and a capacitor C1. In the example of Fig. 1, the main drivers S1 and S2 are made up of FETs. Pre-drivers T1 and T2 of the switching power supply unit 11 are connected to the gates of the main drivers S1 and S2 via output terminals of the power supply device 1, respectively. In the description of this embodiment, a "main driver" is a driver that supplies current to loads LD1 to LD4, and a "pre-driver" is a driver that drives the main driver.

[0022] The source of the main driver S1, the drain of the main driver S2, and one end of the coil L1 are connected, the drain of the main driver S1 is connected to the input power supply (VDD), and the source of the main driver S2 is connected to ground. The connection point between the source of the main driver S1 and the drain of the main driver S2 is connected to a switching power supply unit 11 to monitor the drain-source voltage of the main driver S1. A capacitor C1 is connected between the other end of the coil L1 and ground, and a load LD1 is connected to the connection node between the coil L1 and the capacitor C1. The connection node between the coil L1 and the capacitor C1 is also connected to the switching power supply unit 11 for feedback control (error detection). A step-down switching regulator is formed by the switching power supply unit 11 and an external circuit E1, and its output voltage is provided to the load LD1.

[0023] The switching power supply unit 12 (second switching power supply unit) includes a high-side pre-driver T3 and a main driver T5, and a low-side pre-driver T4 and a main driver T6. In the example of FIG. 1, the main drivers T5 and T6 are configured with FETs. The pre-driver T3 and the pre-driver T4 are configured with switching elements such as FETs. The source of the main driver T5 and the drain of the main driver T6 are connected to the output terminal of the power supply device 1. The main drivers T5 and T6 supply current to an external circuit E2 and further supply current to a load LD2 via the external circuit E2. The pre-drivers T3 and T4 are connected to the gates of the main drivers T5 and T6, respectively, and the main drivers T5 and T6 are driven by the pre-drivers T3 and T4, respectively. The drain of the main driver T5 is connected to the output of the external circuit E1 (the switching power supply output (VDD2) from the switching power supply unit 11), and the source of the main driver T6 is connected to ground.

[0024] The external circuit E2 includes a coil L2 and a capacitor C2. One end of the coil L2 is connected to the main drivers T5 and T6 via the output terminal of the power supply device 1, and the capacitor C2 is connected between the other end of the coil L2 and ground. In addition, the connection node between the coil L2 and the capacitor C2 is connected to the switching power supply unit 12 for feedback control (error detection). The switching power supply unit 12 and the external circuit E2 form a step-down switching regulator, and its output voltage is provided to a load LD2 connected to the coil L2 and the capacitor C2.

[0025] The switching power supply unit 13 (third switching power supply unit) includes a pre-driver T7 (low side). The pre-driver T7 is composed of a switching element such as an FET. The output of the pre-driver T7 is connected to the output terminal of the power supply 1. The external circuit E3 includes a main driver S3 (low side), a coil L3, a capacitor C3, and a diode D1. In the example of FIG. 1, the main driver S3 is composed of an FET. The pre-driver T7 is connected to the gate of the main driver S3 via the output terminal of the power supply 1. One end of the coil L3 and the anode of the diode D1 are connected to the drain of the main driver S3. The other end of the coil L3 is connected to the input power supply (VDD). A capacitor C3 is connected between the cathode of the diode D1 and ground. The connection node between the capacitor C3 and the diode D1 is connected to the switching power supply unit 13 for feedback control (error detection). The switching power supply unit 13 and the external circuit E3 form a step-up switching regulator, and its output voltage is provided to a load LD3 connected to the capacitor C3 and the diode D1.

[0026] The switching power supply unit 14 (fourth switching power supply unit) is configured in the same manner as the switching power supply unit 12. The drain of the main driver on the high side is connected to the output of the external circuit E3 (the output (VDD4) of the switching power supply by the switching power supply unit 13). The external circuit E4 is configured in the same manner as the external circuit E2. The switching power supply unit 14 and the external circuit E4 form a step-up switching regulator, the output voltage of which is provided to the load LD4.

[0027] Each pre-driver and each main driver constituting any one of the switching power supply units 11 to 14 may be configured with a bipolar transistor or a junction-type FET. Each pre-driver may include high-side and low-side switching elements. Furthermore, each pre-driver may have a multi-stage structure that enhances driving capability over two or more stages, for example, by connecting the inputs and outputs of multiple drivers configured with FETs, and driving subsequent drivers by preceding drivers.

[0028] The communication unit 3 receives signals related to the control of the power supply device 1 from the external device M in accordance with a predetermined communication standard such as SPI or I2C, and outputs a signal based on the received signal to the control unit 2. The communication unit 3 may also transmit a signal (e.g., a response signal) to be sent from the power supply device 1 to the external device M. The example in FIG. 1 is an example in which the communication unit 3 and the external device M communicate in accordance with the SPI protocol, and the communication unit 3 is connected to the external device M by three signal lines: a clock line SCK, a data input line SDI, and a data output line SDO.

[0029] The control unit 2 includes a logic control circuit 2a, an input / output circuit 2b, a voltage monitor circuit 2c, and a self-diagnosis circuit 2d. The logic control circuit 2a controls the switching operation of each of the switching power supply units 11-14 based on instructions from the external device M received via the communication unit 3, control signals of a predetermined level received from the input / output circuit 2b, and the contents stored in a built-in ROM (not shown). For example, the logic control unit 2a outputs predetermined signals to each of the switching power supply units 11-14 to control the start and stop of switching in each of the switching power supply units 11-14 and the switching start sequence between the switching power supply units 11-14.

[0030] Control unit 2 may have a thermal shutdown function. For example, it may detect the temperature of power supply device 1 using a temperature detection element (not shown), and when the detected temperature exceeds a predetermined temperature that is appropriately lower than the junction temperature of the semiconductor devices that make up power supply device 1, it may send a shutdown signal to switching power supply units 11-14 to stop switching by switching power supply units 11-14.

[0031] The voltage monitor circuit 2c and the self-diagnosis circuit 2d work together to detect a fault in the power supply device 1. That is, these two circuits detect that the desired voltage is not being supplied from the power supply device 1 to each of the loads LD1-LD4. Therefore, the connection nodes between the loads LD1-LD4 and the external circuits E1-E4 are connected to the voltage monitor circuit 2c via the input terminals of the power supply device 1. The voltage monitor circuit 2c sends a test signal corresponding to the input voltage (the voltage supplied to each load) to the self-diagnosis circuit 2d.

[0032] The self-diagnosis circuit 2d compares the voltage indicated by the signal under test with a failure judgment standard, and if the voltage indicated by the signal under test exceeds the standard for determining normality, it outputs an error signal to the outside via the output terminal of the power supply device 1. In the example of Figure 1, the self-diagnosis circuit 2d is connected to an external device M, which is a microcomputer. When the external device M, which is a microcomputer, receives the error signal, it executes fail-safe processing in the device or system in which the power supply device 1 is used, such as stopping operation or transitioning to a predetermined safe state.

[0033] The input / output circuit 2b accepts the application of a signal or voltage that is input to the power supply device 1 by a method other than communication via the communication unit 3. The input / output circuit 2b outputs the input signal or applied voltage to the logic control circuit 2a either directly or after performing necessary processing. In the example of FIG. 1, one input port of the input / output circuit 2b is connected to the input terminal 4. The input / output circuit 2b may output the signal or predetermined voltage received from the logic control circuit 2a to an external device M or the like.

[0034] The input / output circuit 2b may have a function of generating a signal or voltage corresponding to an input signal or voltage and outputting it to the outside (for example, to an external device M). For example, the input / output circuit 2b may have a function of a watchdog timer that monitors whether the external device M (microcomputer) is operating normally. In this case, the input / output circuit 2b may receive a pulse signal (clear pulse) output from the external device M at regular intervals, and if the clear pulse is not input for a predetermined period or longer, output a reset signal to the external device M from an output terminal (not shown).

[0035] Input terminal 4 is an external terminal provided on power supply device 1 so that a desired signal or voltage of a desired magnitude can be applied from outside power supply device 1. Input terminal 4 is configured to receive an input signal that provides instructions to control unit 2. Therefore, the internal circuitry of power supply device 1 is configured so that information indicated by the signal or voltage input to input terminal 4 is transmitted to control unit 2.

[0036] As described below, a signal for stopping the switching of the switching power supply units 11-14 is input to the input terminal 4. In the example of FIG. 1, the input terminal 4 is connected to the input / output circuit 2b. Therefore, if the input / output circuit 2b has the function of a watchdog timer as described above, the above-mentioned clear pulse from a microcomputer, which is an external device M, may be input to the input terminal 4. That is, the function of the input terminal 4 may be switched in the control unit 2 to accept input of a signal other than the input signal for stopping the switching of the switching power supply units 11-14. Furthermore, the function of the input terminal 4 may be switched in the control unit 2 to output a signal from the power supply device 1. Examples of signals input to the input terminal 4 other than the input signal for stopping the switching of the switching power supply units 11-14 include an input signal that serves as a synchronization signal for the switching power supply device and a write input signal for the built-in ROM. Furthermore, an example of a signal output from the input terminal 4 whose function has been switched to output a signal is an error signal. By configuring the control unit 2 so that the function of the input terminal 4 can be switched, the number of external terminals can be reduced when the power supply device 1 is integrated into a semiconductor integrated circuit device such as a PMIC as in the example of FIG. 1.

[0037] <Configuration of switching power supply section> Next, the switching power supply units 11 to 14 included in the power supply device 1 will be further described using the switching power supply unit 11 in FIG. 1 as an example. FIG. 2 shows the internal configuration of the switching power supply unit 11 together with a simplified control unit 2. As shown in FIG. 2, the switching power supply unit 11 includes an output circuit 11a connected to an output terminal 51 and a switching control circuit 11b. The output circuit 11a includes the pre-driver T1 and pre-driver T2 described with reference to FIG. 1, and switches the current output from the output terminal 51. The switching control circuit 11b controls the switching of the output circuit 11a under the control of the control unit 2. The switching control circuit 11b includes an error amplifier 111, an oscillator 112, a PWM comparator 113, a logic circuit 114, a level shifter 115, and a reference voltage source 119.

[0038] In the switching control circuit 11b, the voltage provided to the load LD1 (the output voltage of the switching power supply constituted by the switching power supply unit 11) is divided by resistors R1 and R2 to form a voltage Ve, which is input to the inverting input terminal of the error amplifier 111. A reference voltage VREF generated by a reference voltage source 119 is applied to the non-inverting input terminal of the error amplifier 111, and the difference voltage between the voltage Ve and the reference voltage VREF is amplified and output from the error amplifier 111. Note that the reference voltage source 119 is provided with a soft start function so that the voltage it generates reaches the voltage VREF in, for example, several milliseconds after power is applied to the power supply device 1, in order to reduce the inrush current when the power supply device 1 starts up.

[0039] The oscillator 112 outputs a triangular wave having a frequency of, for example, several MHz. This triangular wave is compared with the output of the error amplifier 111 by the PWM comparator 113, and a pulse signal having a pulse width corresponding to the difference between the voltage applied to the load LD1 and the desired voltage to be applied to the load LD1 is input to the logic circuit 114. The logic circuit 114 outputs a switching signal having the pulse width of the input pulse signal to the level shifter 115 and also to the low-side pre-driver T2. The level shifter 115 shifts the level of the switching signal received from the logic circuit 114 to a level suitable for driving the high-side pre-driver T1 and outputs the signal to the pre-driver T1. As a result, the pre-drivers T1 and T2 switch the output current passing through the output terminal 51 at intervals suitable for bringing the voltage applied to the load LD1 close to the desired voltage.

[0040] The switching control circuit 11b in the example of FIG. 1 further includes an overheat protection circuit 116, an overvoltage protection circuit 117, and an overcurrent protection circuit 118. The overheat protection circuit 116 detects that the temperature of the switching power supply unit 11 exceeds a predetermined temperature and outputs the detection result to the logic circuit 114. The overvoltage protection circuit 117 detects that the voltage applied to the load LD1 exceeds a predetermined voltage and outputs the detection result to the logic circuit 114. The overcurrent protection circuit 118 detects that the current flowing through the pre-drivers T1 and T2 and the main drivers S1 and S2 exceeds a predetermined current and outputs the detection result to the logic circuit 114. When the logic circuit 114 receives detection results from these protection circuits indicating that overheating, overvoltage, and / or overcurrent has occurred, it stops outputting switching signals, for example.

[0041] The other switching power supply units 12 to 14 shown in Fig. 1 may also be configured in the same manner as the switching power supply unit 11 in Fig. 2. However, in switching power supply unit 12, output circuit 11a includes pre-drivers T3 and T4 and main drivers T5 and T6 (see Fig. 1), in switching power supply unit 13, output circuit 11a includes only pre-driver T7 (see Fig. 1), and in switching power supply unit 14, output circuit 11a includes two pre-drivers and two main drivers, similar to switching power supply unit 12.

[0042] That is, in each of the switching power supply units 11 to 14, the output circuit 11a is composed of at least a driver connected to the output terminal of the power supply device 1. Then, as in the multi-stage structure described above, if there is a preceding driver that drives a driver (subsequent driver) connected to the output terminal, the output circuit 11a can be composed of the subsequent driver and all of the preceding drivers. On the other hand, the switching control circuit 11b is composed of circuits other than the output circuit 11a in each of the switching power supply units 11 to 14.

[0043] The output circuit 11a can also be defined as a circuit block configured with a group of circuit elements that operate at an amplitude that exceeds the amplitude between high and low levels that an internal node of the logic circuit 114 can take. That is, a power supply voltage that is higher than the power supply voltage applied to the logic circuit 114 may be applied to the pre-drivers T1, T2, etc. In this case, the pre-drivers T1, T2, etc. can operate at an amplitude that exceeds the amplitude between high and low levels that the logic circuit 114 can take.

[0044] <Noise interference in communication signals> In a power supply device such as the power supply device 1 shown in Figures 1 and 2 that has a switching power supply and transmits and receives signals via communication with external devices, as mentioned above, the switching of the switching power supply interferes with the communication signal, easily generating noise in the communication signal. Figure 3 shows, as an example, the waveform fv of the output voltage of a switching power supply of a power supply device such as the power supply device 1 and the waveform fc of a communication signal (corresponding to the signal transmitted over the data input line SDI in the power supply device 1 of Figure 1). Note that the waveform fc in Figure 3 is an enlarged view of the timing of the H level of the actual communication signal. In the power supply device in which the waveforms fc and fv in Figure 3 are observed, the switching power supply is operating at a switching frequency of 1 MHz. Both waveforms fv and fc exhibit spike noise with a period (500 nanoseconds) of 1 / (2 × switching frequency), which is synchronized with the switching timing.

[0045] If such noise is superimposed on communication signals, for example, signals sent from external devices may be incorrectly received by the power supply, or may not be received at all, making it impossible to control the power supply via communication. However, stopping the entire power supply's function disables communication itself, and lowering the power supply's switching frequency makes it difficult to achieve the power supply's intended performance. Furthermore, completely stopping the operation of elements that switch the switching power supply unit, such as oscillator 112 and reference voltage source 119 described with reference to Figure 2, will require unnecessary startup time when restarting switching if the power supply is equipped with a soft start function, as mentioned above.

[0046] <Stopping switching of the output circuit of the switching power supply> Therefore, in this embodiment, a power supply device is configured to solve this problem. Referring again to FIGS. 1 and 2, the configuration of the power supply device 1 of this embodiment will be described. The power supply device 1 of this embodiment is configured to be able to stop the switching of the output circuit 11a while keeping the switching control circuit 11b included in each switching power supply unit functioning, without relying on communication. That is, the control unit 2 is configured to stop the switching of the output circuit 11a while keeping the switching control circuit 11b functioning, in response to an input signal to the input terminal 4 of the power supply device 1. When the switching of the output circuit 11a is stopped, the power supply 1 and its surroundings do not rapidly switch between on and off of a relatively large current, or the direction of current flow does not reverse. Therefore, even if oscillation or switching continues within the switching control circuit 11b, noise due to switching is unlikely to be introduced into the communication signal.

[0047] For example, as shown in FIG. 2 , a high-level or low-level signal input to the input terminal 4 may be input as a stop signal Sp to the logic circuit 114 of the switching power supply unit 11 via the control unit 2, as indicated by the dashed line in FIG. 2 . In this case, the waveform of the signal input to the input terminal 4 may be shaped by a buffer 2e in the control unit 2. Alternatively, the control unit 2 may newly generate a stop signal Sp that inverts the level in response to application of a low-level voltage or a high-level voltage to the input terminal 4, and output the generated stop signal to the logic circuit 114. The logic circuit 114 may then stop outputting the switching signal to the level shifter 115 and the output circuit 11a while the stop signal Sp is at a low level or a high level. Furthermore, when the level shifter 115 has an output disable function, the stop signal Sp may be input to the level shifter 115, and the level shifter 115 may stop outputting the switching signal to the output circuit 11a. The level shifter 115 may also be provided between the logic circuit 114 and the pre-driver T2, as appropriate.

[0048] Furthermore, control unit 2 may use the thermal shutdown function described above to stop the switching of output circuit 11a. That is, when a high-level or low-level voltage is applied to input terminal 4, control unit 2 may send a shutdown signal to logic circuit 114 even if the temperature detected by a temperature detection element (not shown) does not exceed a predetermined temperature. At this time, an accompanying signal indicating that the shutdown signal is not due to a temperature rise but is due to the voltage level input to input terminal 4 may be sent along with the shutdown signal. Then, when logic circuit 114 receives the accompanying signal, switching power supply units 11-14 may perform operations different from those in the case of true thermal shutdown, except for stopping the switching of output circuit 11a.

[0049] In this embodiment, "operating the switching control circuit 11b" means operating at least the error amplifier 111, the reference voltage source 119, the oscillator 112, and the PWM comparator 113 in the same manner as when an input signal for stopping the switching of the output circuit 11a is not input to the input terminal 4. Furthermore, "operating the switching control circuit 11b" may also mean operating some or all of the overheat protection circuit 116, the overvoltage protection circuit 117, and the overcurrent protection circuit 118 in the same manner as when an input signal for stopping the switching of the output circuit 11a is not input to the input terminal 4, in addition to operating these elements.

[0050] Furthermore, in this embodiment, "in response to an input signal to the input terminal...stopping the switching of the output circuit" means, when the output circuit 11a includes a driver with a multi-stage structure as described above, stopping the switching of at least the "subsequent-stage driver" connected to the output terminal (such as the output terminal 51) of the power supply device 1, that is, the driver arranged closest to the load (such as the load LD1). Alternatively, when the output circuit 11a includes a driver with a multi-stage structure, "in response to an input signal to the input terminal...stopping the switching of the output circuit" may mean, in addition to the subsequent-stage driver, stopping the switching of the driver among the aforementioned "previous-stage drivers" through which a current of, for example, 100 mA or more, preferably 50 mA or more flows.

[0051] In this embodiment, the control unit 2 is configured to stop the switching of the output circuit 11a in response to an input signal to the input terminal 4. For example, by inputting a signal of a predetermined voltage level, such as a high-level voltage or a low-level voltage, to the input terminal 4, the switching of the output circuit 11a is stopped. Therefore, the power supply device 1 can be appropriately controlled using a communication signal with little noise. Furthermore, in this embodiment, the switching of the output circuit 11a is stopped while the switching control circuit 11b continues to function, so that, for example, after receiving a control signal from the external device M, the switching power supply units 11-14 can be operated quickly. Therefore, according to this embodiment, the power supply device can be controlled by communication without being affected by the switching power supply or sacrificing characteristics, and further, a power supply device can be provided that can output a desired voltage quickly after control by communication.

[0052] Note that a signal of a predetermined voltage level can be applied to the input terminal 4 by any method. For example, as shown by the dashed line in Fig. 1 , the input terminal 4 may be connected to an external device M such as a microcomputer, and a signal may be input from the external device M to the input terminal 4. Then, a control signal may be transmitted from the external device M to the communication unit 3.

[0053] Furthermore, when the control unit 2 stops the switching of the output circuit 11a of the switching power supply units 11-14 in response to the input signal to the input terminal 4, the control unit 2 may cause the communication unit 3 to transmit a confirmation signal indicating that the switching of the output circuit 11a has stopped to the external device M. After receiving this confirmation signal, that is, after confirming that the situation is one in which noise is unlikely to occur, the external device M may transmit a control signal to the power supply device 1. This is thought to ensure more reliable and appropriate communication.

[0054] 1 includes a plurality of switching power supply units 11 to 14. All of the switching power supply units 11 to 14 may be configured by the control unit 2 to stop the switching of the output circuit 11a while keeping the switching control circuit 11b functioning in response to an input signal to the input terminal 4, or only some of the switching power supply units may be configured to stop switching. Even in this case, noise occurring in the communication signal may be reduced.

[0055] Alternatively, the plurality of switching power supply units 11-14 may each have a corresponding input terminal 4, i.e., a plurality of input terminals 4. Then, in response to an input signal to an individual input terminal 4, only the switching of the output circuit 11a of the corresponding switching power supply unit among the plurality of switching power supply units 11-14 may be stopped. Alternatively, the control unit 2 may be configured to stop the switching of the output circuit 11a of each of the plurality of switching power supply units 11-14 simultaneously, while keeping the switching control circuit 11b functioning, in response to an input signal to the only input terminal 4 provided. This is thought to more easily and reliably reduce noise occurring in communication signals.

[0056] <Example of using switching stop> Referring to FIG. 4, an example of how the switching of the output circuit 11a can be stopped without stopping the overall function of the power supply 1 or the function of the switching control circuit of the switching power supply unit will be described. First, by stopping only the switching of the output circuit 11a of the switching power supply unit, it is possible to test whether a failure processing function, such as a fail-safe process, operates normally in the event of a failure in a device or system using the power supply 1. That is, the power supply 1 may be equipped with the voltage monitor circuit 2c and the self-diagnosis circuit 2d as described above. If the self-diagnosis circuit 2d determines that a failure has occurred, it generates an error signal that is sent to an external device M, such as a microcomputer, as shown in FIG. 4. The external device M is programmed with a process for when the power supply 1 fails, and is configured to operate in accordance with that program when a failure occurs. Therefore, by intentionally stopping switching in the power supply 1 to simulate a failure state, it is possible to test whether the external device M and the devices and systems controlled by the external device M that receive the error signal operate appropriately in the event of a failure. The function of the entire power supply device 1 is not stopped, that is, the voltage monitor circuit 2c and the self-diagnosis circuit 2d are functioning, so that it is possible to test the operation in the event of such a failure.

[0057] Furthermore, by configuring the output circuit 11a so that only the low-side switching of the output circuit 11a can be stopped, it is possible to check whether the low-side main driver S2 (and pre-driver, not shown) is functioning normally. Specifically, as shown in FIG. 4, because the FETs constituting the main driver S2 and other components have body diodes, even if the low-side is faulty, the switching power supply may appear to output the intended voltage, making it difficult to detect the fault. A low-side fault increases current consumption, but because the power supply device 1 itself varies in current consumption, it is difficult to detect a low-side fault simply by checking the current consumption. Therefore, by intentionally stopping only the switching of the low-side driver, a low-side fault can be detected by observing the change in current consumption before and after the intentional stopping of switching. Specifically, if the current consumption does not increase by more than a certain value before and after intentionally stopping switching, it can be determined that the low-side driver is faulty.

[0058] Furthermore, by stopping only the switching of the output circuit 11a, it is possible to improve the EMC (Electromagnetic Compatibility) performance of the equipment or system in which the power supply device 1 is used. That is, by stopping only the switching of the output circuit 11a in the power supply device 1 and performing an EMC test on the equipment or system, it is possible to identify the source of EMC noise as the output circuit 11a or the main drivers S1 and S2 beyond it, or to exclude these from the list of suspected sources. Therefore, it is possible to efficiently find countermeasures and improve EMC performance.

[0059] <Test methods for power supply units> Next, a method for testing a power supply device according to an embodiment of the present invention will be described with reference to Figures 1 and 2, taking as an example a case where the power supply device 1 shown in Figures 1 and 2 is tested. Additionally, a method for controlling the power supply device according to an embodiment of the present invention via communication, and a method for reducing noise superimposed on a communication signal in the power supply device according to an embodiment of the present invention will be described.

[0060] The method for testing a power supply device according to this embodiment is a method for testing a power supply device that includes one or more switching power supply units and is controlled by communication. Taking the power supply device 1 shown in FIG. 1 as an example, the method for testing a power supply device according to this embodiment includes stopping the switching of output circuit 11a while keeping switching control circuit 11b functioning, both of which are included in switching power supply units 11-14: output circuit 11a that switches the output current of power supply device 1, and switching control circuit 11b that controls the switching of output circuit 11a. The method for testing power supply device 1 according to this embodiment further includes resuming the switching of output circuit 11a that has been stopped, and measuring at least one characteristic of power supply device 1.

[0061] As described above with reference to FIG. 3, in a power supply device including a switching circuit constituting a switching power supply, such as the switching power supply units 11-14 of the power supply device 1, noise is likely to occur in communication signals between the device and external devices. Therefore, when measuring multiple characteristics of the power supply device by sequentially switching the mode of the power supply device to a state (mode) suitable for measuring each characteristic, it may not be possible to quickly and appropriately set or switch the mode of the power supply device through communication. In such cases, as described above, the test time may increase, or a non-defective product may be judged as defective, resulting in a reduction in apparent yield. Furthermore, if the switching frequency during testing is too low, it may not be possible to test whether the desired characteristics are obtained under the expected operating conditions.

[0062] Therefore, the power supply device testing method of this embodiment, in the case of the power supply device 1 of FIG. 1, includes stopping the switching of the output circuit 11a while keeping the switching control circuit 11b functioning. Then, after restarting the stopped switching of the output circuit 11a, at least one characteristic of the power supply device 1 is measured. Because the switching of the output circuit 11a is stopped, noise occurring in communication signals can be reduced. Therefore, during that time, a control signal can be sent via communication to correctly set or change the test mode of the power supply device 1. Then, when the switching of the output circuit 11a is restarted to perform measurements in that test mode, the switching control circuit 11b continues to function even while the output circuit 11a is stopped, so the switching of the output circuit 11a can be quickly restarted.

[0063] As described above, the power supply device testing method of this embodiment allows the power supply device to be tested easily, appropriately, and in a short time. Note that, in the case of power supply device 1 of Fig. 1, "operating the switching control circuit" means operating at least error amplifier 111, reference voltage source 119, oscillator 112, and PWM comparator 113 shown in Fig. 2 in the same manner as when the switching of output circuit 11a is not stopped.

[0064] The power supply device 1 in FIGS. 1 and 2 includes an input terminal 4 that receives an input signal that stops the switching of the output circuit 11a of the switching power supply units 11-14. Therefore, in the method for testing the power supply device of this embodiment, stopping the switching of the output circuit may include applying a predetermined signal to one input terminal, such as the input terminal 4 included in the power supply device 1, without relying on communication. Because the predetermined signal is applied without relying on communication, even if the output circuit 11a in the power supply device 1 is performing switching, for example, an intended signal can be input to the input terminal 4. By inputting a predetermined signal, such as a low-level voltage or a high-level voltage, to the input terminal 4, the power supply device 1 can stop the switching of the output circuit 11a while keeping the switching control circuit 11b functioning.

[0065] According to the power supply device testing method of this embodiment, the mode of the power supply device can be appropriately set or changed via communication by stopping the switching of the output circuit. Referring to FIGS. 5 and 6 in addition to FIGS. 1 and 2, a testing method for switching the test mode of the power supply device will be described, taking the power supply device 1 of FIGS. 1 and 2 as an example. FIG. 5 shows a flowchart of an example of the power supply device testing method of this embodiment, and FIG. 6 shows a timing chart of the testing method. In FIG. 6, VDD indicates the internal power supply voltage of the power supply device 1. Sw1 to Sw4 indicate the switching states of the output circuits 11a of the switching power supply units 11 to 14, respectively, with switching occurring during intervals indicated by small pulses. Si indicates an input signal to the input terminal 4. In FIG. 6, a low-level voltage input stops the switching of the output circuits 11a in the switching power supply units 11 to 14. Pc is a control pulse in the control signal received by the communication unit 3 that instructs the power supply device 1 to change modes. In FIG. 6, the test mode of the power supply device 1 is switched in the order of test modes M1, M2, M3, M4, . . . each time a control pulse Pc is received.

[0066] When a power supply voltage is applied to the power supply device 1 (step ST1 in FIG. 5), the internal power supply voltage VDD rises, as shown in FIG. 6. However, due to sequence control by the control unit 2 (see FIG. 1), switching does not immediately begin in any of the switching power supply units 11-14. Then, at time t1 in FIG. 6, a control pulse Pc is input. At time t1, switching has not yet begun in any of the switching power supply units 11-14, so the control pulse Pc is correctly transmitted to the control unit 2, and the state of the power supply device 1 is set to the first test mode M1 (step ST2 in FIG. 5). Then, switching begins in each of the switching power supply units 11-14. That is, the switching control circuit 11b (see FIG. 2) of each switching power supply unit functions through the generation of a reference voltage by the reference voltage source 119, the oscillation of the oscillator 112, and the comparison operation of the PWM comparator 113, causing the output circuit 11a to switch. Also, a high-level voltage is input as the input signal Si. Then, in the first test mode M1, the first characteristic of the power supply device 1 is measured (step ST3 in FIG. 5).

[0067] Examples of the first characteristic and the second to fourth characteristics described below include the switching frequency, the duty ratio of the switching pulse, the on-resistance of the FETs constituting the driver, and the output voltage of each switching power supply unit, but the characteristics measured in testing the power supply device 1 are not limited to these. Furthermore, the first test mode M1 and the second to fourth test modes described below are any modes that the power supply device 1 has and are suitable for measuring the first to fourth characteristics.

[0068] Thereafter, at time t2, a low-level voltage is input by the input signal Si, and the control unit 2 stops switching of the output circuit 11a (step ST4 in FIG. 5). In FIG. 6, switching is stopped in all of the switching power supply units 11-14 due to the input of a low-level voltage by the input signal Si to the input terminal 4. While the voltage of the input signal Si is at a low level, switching is continuously stopped in all of the switching power supply units 11-14. Note that although switching of the output circuit 11a has stopped, the switching control circuit 11b continues to function.

[0069] Then, while switching is stopped in each switching power supply unit, a control pulse Pc is sent via communication at time t3. Because switching in output circuit 11a is stopped, the control pulse Pc is properly transmitted to control unit 2, and the test mode of power supply device 1 is set to a second test mode suitable for the next measurement (step ST5 in FIG. 5). Also, at time t4, a high-level potential is input as input signal Si, and switching is resumed in output circuits 11a of switching power supply units 11-14 (step ST6 in FIG. 5). Then, the second characteristic of power supply device 1 is tested in the second test mode (step ST7 in FIG. 5).

[0070] Thereafter, the test mode is switched to a third test mode M3, a fourth test mode M4, etc., and the third characteristic, the fourth characteristic, etc. are measured in sequence. The test ends when all desired characteristics have been measured. In the example of FIG. 6, in the third test mode M3, switching remains stopped in each switching power supply unit. This is because the third test mode M3 measures characteristics that can be measured with the switching of the output circuit 11a stopped, such as the on-resistance of the FETs constituting the output circuit 11a and other DC characteristics. When switching from a test mode in which the switching of the output circuit 11a is stopped to the next test mode, unlike the example of FIG. 6, a signal of a predetermined voltage level does not need to be input to the input terminal 4 to stop the switching of the output circuit 11a.

[0071] As shown in Figures 5 and 6, the testing method for the power supply device of this embodiment may further include, for example, in the case of the power supply device 1 of Figures 1 and 2, measuring a first characteristic of the power supply device 1 in a first test mode before stopping the switching of the output circuit 11a, switching the power supply device 1 from the first test mode M1 to a second test mode M2 ​​by communication while the switching of the output circuit 11a is stopped, and resuming the switching of the stopped output circuit 11a to measure a second characteristic of the power supply device 1 in the second test mode M2.

[0072] Furthermore, in testing a power supply device including multiple switching power supply units as in the example of Figure 6, taking power supply device 1 of Figure 1 as an example, by applying a predetermined signal to one input terminal such as input terminal 4, switching of output circuit 11a may be stopped in each of multiple switching power supply units 11-14 while switching control circuit 11b continues to function. Note that even if the power supply device under test includes multiple switching power supply units, switching may be stopped in only one or some of the switching power supply units, and a control signal for switching the test mode may be sent via communication during that time. This is because noise generated in the communicated signal can also be reduced in this case.

[0073] Note that a plurality of power supply devices may be tested using the power supply device testing method of this embodiment. Figure 7 shows a timing chart similar to Figure 6 for two of the plurality of power supply devices being tested simultaneously. SwA1 to SwA4 indicate the switching states of the four switching power supply units of one of the two power supply devices being tested, and SwB1 to SwB4 indicate the switching states of the four switching power supply units of the other of the two power supply devices being tested. VDD, Si, and Pc are used in the same manner as in Figure 6.

[0074] 7, when a power supply voltage VDD is applied simultaneously to multiple power supply devices, switching begins in each switching power supply unit of each power supply device. Then, at time t2, when a low-level voltage is applied by input signal Si, switching is stopped in all switching power supply units of each of the multiple power supply devices, as shown by SwA1-SwA4 and SwB1-SwB4, which indicate the switching states. Then, after input of control pulse Pc at time t3, when a high-level voltage is applied by input signal Si at time t4, switching resumes in all switching power supply units of each of the multiple power supply devices. Then, a test of the desired characteristics is performed in the test mode switched by input of control pulse Pc.

[0075] In this way, when a plurality of power supply devices, such as the power supply devices 1 illustrated in Fig. 2, are tested using the power supply device testing method of this embodiment, the switching of the output circuits 11a of the plurality of power supply devices 1 may be stopped simultaneously while the switching control circuits 11b of each of the plurality of power supply devices 1 continue to function, allowing many power supply devices to be tested efficiently.

[0076] <Method for controlling power supply units through communication> A method for controlling a power supply device via communication (hereinafter also referred to as "this control method") according to one embodiment of the present invention is a method for controlling a power supply device via communication, such as the power supply device 1 shown in FIG. 1, which includes one or more switching power supply units 11-14 and a communication unit 3 that receives a control signal from an external device. This control method is similar to the communication-based control method for a power supply device in the previously described method for testing a power supply device according to one embodiment. Therefore, using the power supply device 1 shown in FIGS. 1 and 2 as an example, this control method includes stopping the switching of output circuit 11a while keeping switching control circuit 11b functioning, both of which are included in switching power supply units 11-14 and control the switching of output circuit 11a. This control method further includes controlling power supply device 1 by sending a control signal to communication unit 3 while the switching of output circuit 11a is stopped. Therefore, this control method allows the power supply device to be controlled via communication without being affected by the switching power supply, and also allows the power supply device to output a desired voltage promptly after the control.

[0077] In addition, the items that the power supply device 1 controls through communication while switching of the output circuit 11a is stopped include, for example, setting or switching the test mode as mentioned above, changing the output voltage, changing the switching frequency, and thresholds for overheating judgment, overcurrent judgment, and / or overvoltage judgment, but the items that are controlled while switching is stopped are not limited to these.

[0078] Furthermore, as described in the explanation of the power supply device testing method of one embodiment, when the power supply device includes multiple switching power supply units, in this control method, taking the power supply device 1 shown in Figures 1 and 2 as an example, by applying a predetermined signal to one input terminal such as input terminal 4 of power supply device 1, switching of output circuits 11a in each of the multiple switching power supply units 11 to 14 may be stopped all at once while switching control circuit 11b continues to function. This is thought to enable more reliable and efficient control of the power supply device.

[0079] <Method for reducing noise superimposed on communication signals in a power supply device> A method for reducing noise superimposed on a communication signal in a power supply device according to one embodiment of the present invention (hereinafter also referred to as "this noise reduction method") is a method for reducing noise superimposed on a communication signal in a power supply device that includes one or more switching power supply units 11-14 and is controlled by communication, such as the power supply device 1 shown in FIG. 1. This noise reduction method is similar to the noise reduction method in the power supply device testing method described above. Therefore, using the power supply device 1 shown in FIGS. 1 and 2 as an example, this noise reduction method includes applying a power supply voltage to the power supply device 1 to activate a switching control circuit 11b that controls an output circuit 11a included in the switching power supply units 11-14, and stopping the switching of the output circuit 11a while keeping the switching control circuit 11b active. Therefore, this noise reduction method allows the power supply device to be controlled by communication without being affected by the switching power supply, and also allows the power supply device to output the desired voltage promptly after control.

[0080] In this noise reduction method, the switching of the output circuit may be stopped by inputting a predetermined signal to an input terminal such as the input terminal 4 of the power supply device 1 in the example of Figure 1, or by using any other means that can stop the switching of the output circuit while allowing the switching control circuit to continue functioning.

[0081] Although embodiments of a method for reducing noise superimposed on a communication signal in a power supply device, a method for controlling a power supply device by communication, and a method for testing a power supply device have been described using the power supply device 1 of Figures 1 and 2 as an example, each of these methods can be applied to any power supply device that includes a switching power supply unit and is controlled by communication. [Explanation of symbols]

[0082] 1 Power supply 11-14 Switching power supply section 11a Output circuit 11b Switching control circuit 111 Error amplifier 112 Oscillator 113 PWM Comparator 119 Reference Voltage Source 2. Control Unit 3. Communications Department 4 input terminals E1~E4 External circuit LD1~LD4 load M External device M1~M4 test modes Si input signal

Claims

1. one or more switching power supply units that switch the supply of current to an external circuit; a control unit that controls each of the one or more switching power supply units; a communication unit that transmits and receives signals between the control unit and an external device; an input terminal that receives an input signal that gives an instruction to the control unit; A power supply device comprising: each of the one or more switching power supply units includes an output circuit connected to an output terminal for switching an output current, and a switching control circuit for controlling the output circuit; The control unit The switching control circuit is configured to stop switching of the output circuit while allowing the switching control circuit to function in response to an input signal to the input terminal, and When the switching is stopped, a signal indicating that the switching is stopped is transmitted from the communication unit to the external device, A power supply device configured to be controlled by a control signal received by the communication unit while the switching is stopped.

2. 2. The power supply device according to claim 1, wherein the function of the input terminal is switched to accept an input of a signal other than the input signal that stops the switching or to output a signal from the power supply device.

3. the one or more switching power supply units include a plurality of switching power supply units, 3. The power supply device according to claim 1, wherein the control unit is configured to stop the switching of the output circuit in each of the plurality of switching power supply units while keeping the switching control circuit functioning, in response to an input signal to the input terminal.

4. A method for controlling a power supply device via communication, the power supply device including one or more switching power supply units and a communication unit that receives signals from an external device, comprising: an output circuit for switching an output current and a switching control circuit for controlling the output circuit, the output circuit being included in the switching power supply unit, the switching control circuit being included in the switching power supply unit, and stopping the switching of the output circuit while allowing the switching control circuit to function; controlling the power supply device by sending a control signal to the communication unit while the switching is stopped; When the switching is stopped, a signal indicating that the switching is stopped is transmitted from the communication unit to the external device. A method for controlling a power supply device through communication, comprising:

5. the one or more switching power supply units include a plurality of switching power supply units, 5. The method for controlling a power supply device via communication as claimed in claim 4, wherein stopping the switching of the output circuit includes applying a predetermined signal to one input terminal included in the power supply device, thereby stopping the switching of the output circuit in each of the plurality of switching power supply units while keeping the switching control circuit functioning.

6. A test method for a power supply device that includes one or more switching power supply units and is controlled by communication, comprising: an output circuit for switching an output current and a switching control circuit for controlling the output circuit, the output circuit being included in the switching power supply unit, the switching control circuit being included in the switching power supply unit, and stopping the switching of the output circuit while allowing the switching control circuit to function; switching the power supply device from a first test mode to a second test mode through the communication while the switching is stopped; and resuming the stopped switching to measure at least one characteristic of the power supply device in the second test mode.

7. measuring a first characteristic of the power supply device in the first test mode before stopping the switching of the output circuit; 7. The method of testing a power supply device according to claim 6, further comprising measuring a second characteristic of the power supply device in the second test mode.

8. Stopping the switching of the output circuit includes:

8. A method for testing a power supply device according to claim 6, further comprising applying a predetermined signal to one input terminal included in the power supply device without relying on communication, thereby stopping the switching of the output circuit while keeping the switching control circuit functioning.

9. testing a plurality of power supply devices using the power supply device testing method according to any one of claims 6 to 8; A method for testing a plurality of power supply devices, wherein stopping the switching of the output circuit includes simultaneously stopping the switching of the output circuit in the plurality of power supply devices while keeping the switching control circuit of each device functioning.

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