JP6423772B2 - Electronic devices with high resistance to power supply voltage fluctuations - Google Patents

Description

  The present invention relates to an electronic device that operates by receiving power supply from an external power supply device, and more particularly, to an electronic device that is less susceptible to fluctuations in output voltage of the power supply device.

  2. Description of the Related Art Conventionally, in a control device that includes a booster circuit that boosts the voltage of a power supply device, for example, voltage fluctuation of the power supply that occurs due to fluctuations in load current to a motor connected to the power supply device gives the operation of the control device. In order to reduce the influence, the output of the booster circuit is connected to a power supply line from the power supply device via a Zener diode, or between another power supply circuit and a control CPU operated by the power supply circuit. There is known a “fuel injection device for an internal combustion engine” that is connected via a Zener diode (Patent Document 1).

  In this device, when the supply voltage from the power supply device is lower than the value obtained by subtracting the breakdown voltage of the Zener diode from the output voltage value of the booster circuit, the output capacitor of the booster circuit is passed through the Zener diode. By causing a current to flow to the power supply line or the output line of the other power supply circuit, the amount of voltage drop in the power supply line or the output line of the other power supply circuit is reduced.

  However, the amount of charge stored in the output capacitor of the booster circuit is limited, and the current that can be replenished from the output capacitor to other power supply lines is limited. There are limits. In particular, in a configuration in which the output line of the booster circuit is connected to a power supply line from an external power supply device, a large and / or large current load can be connected to the power supply line. As the amount increases, the boosted voltage that is the output of the booster circuit (the voltage across the output capacitor of the booster circuit) also decreases, which may affect the operation of other circuits that use the boosted voltage. .

  In the configuration in which the output line of the booster circuit is connected between another power supply circuit and the CPU via a Zener diode, for example, depending on the components used, the voltage is supplied to the CPU due to the temperature variation of the breakdown voltage of the Zener diode. It is conceivable that the voltage value greatly fluctuates and the operation of the CPU is affected.

JP 2014-9627 A

  From the above background, in an electronic device that operates by receiving power supply from an external power supply device, it is desired to further reduce the influence of output voltage fluctuations of the power supply device and realize more stable operation.

One embodiment of the present invention is an electronic device, wherein a power supply voltage supplied from a power supply device is converted into a first voltage and output, and a power supply voltage supplied from the power supply device is obtained. A second power supply circuit that converts and outputs the second voltage; and at least one third power supply circuit that operates in response to the supply of the second voltage output from the second power supply circuit; The output of the first power supply circuit is connected to the output line of the second power supply circuit from the second power supply circuit to the third power supply circuit via a constant voltage diode.
According to another aspect of the present invention, the image processing apparatus further includes a processing device, the processing device operates by receiving an operating voltage from at least one third power supply circuit, and the first power supply circuit includes the processing device. Supply the operating voltage of the device operating under the control of
According to another aspect of the invention, the first power supply circuit is a booster circuit and the device is a solenoid valve that regulates the fuel supply of an internal combustion engine of a vehicle.
According to another aspect of the present invention, the processing device monitors a power supply voltage output from the power supply device and a first voltage output from the first power supply circuit, and the power supply voltage drops below a predetermined value. Or when the power supply voltage drops below a predetermined value and the first voltage drops below a predetermined value, the load current of the third power supply circuit is limited.
According to another aspect of the present invention, the limitation of the load current of the third power supply circuit is that the processing device stops the operation of a part of the device to which the operating voltage is supplied by the third power supply circuit. And / or by setting the operation mode of the processing apparatus to a low power consumption mode.

It is a circuit diagram which shows the structure of the electronic device which concerns on one Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. The electronic device according to the present embodiment is an electronic control unit (ECU, Electronic Control Unit) that is mounted on a vehicle and controls the operation of an internal combustion engine of the vehicle, for example. However, the present invention is not limited to this, and can be widely applied to general electronic devices having an arbitrary function.

FIG. 1 is a circuit diagram of an electronic device according to an embodiment of the present invention.
The electronic device 10 operates by receiving power from an external power supply device 150 that supplies a power supply voltage V _BAT .

The electronic device 10 includes a CPU (Central Processing Unit) 100 that is a processing device, and outputs a predetermined boosted voltage higher than the power supply voltage V _BAT supplied from the power supply device 150, and under the control of the CPU 100. And a solenoid valve drive circuit 104 that drives a solenoid valve (not shown) such as a fuel injection valve in response to a boosted voltage supplied from the booster circuit 102. In FIG. 1, for easy understanding by omitting the description of the ancillary portion, the solenoid valve driven by the solenoid valve drive circuit 104 and the connection between the solenoid valve and the solenoid valve drive circuit 104 are not shown. The illustration is omitted.

The booster circuit 102 includes, for example, a coil L106 having one end connected to the power supply line of the voltage V _BAT , and a transistor Tr108 that is provided between the other end of the coil L106 and the ground line and turns on and off the coil L106. A diode D110 having an anode connected to the other end of the coil L106, an output capacitor C112 that is charged with a current flowing out from the coil L106 via the diode D110 and outputs a predetermined boosted voltage, and TR108 are turned on / off to boost the operation. And a step-up control circuit 114 for controlling.

  The control circuit 10 also includes a relay RL 116 connected to the power supply line of the power supply device 150. When the coil of the relay RL 116 is turned on / off by a switch 118 controlled by the CPU 100, the internal combustion engine of the vehicle is started. The operation of the starter motor 152 is controlled.

In particular, in the electronic device 10 of the present embodiment, the operation voltage of the CPU 100 that requires a stable operation voltage supply is supplied by a power supply circuit that is connected in cascade and has a two-stage configuration. The first stage is a step-down switching regulator (buck SW regulator) 120 for outputting a voltage lower than the power supply voltage V _BAT by receiving the power supply voltage V _BAT from an external power supply device 150, the second stage is a step-down Power supply circuits 122, 124, and 126 convert the output voltage of the SW regulator 120 to 5V, 3.3V, and 1.2V, which are other voltages necessary for the operation of the CPU 100, respectively.

  The power supply circuits 122, 124, and 126 are, for example, low drop out (LDO) regulators. The 5V and 3.3V voltages output from the power supply circuits 122 and 124 are used, for example, as a logic circuit and clock power supply inside the CPU 100, and the 1.2V voltage output from the power supply circuit 126 is the core of the CPU 100, for example. Used as voltage.

The step-down SW regulator 120 includes, for example, a coil L128, a transistor Tr130 that turns on / off the power supply between the power supply line of the voltage V _BAT and one end of the coil L128, and a shot connected between the other end of the coil L128 and the ground. It has a key barrier diode D132, an output capacitor C134 that is charged by a current flowing out from the coil L128 and outputs a predetermined step-down voltage, and a step-down control circuit 136 that controls the step-down operation by turning on and off TR130.

  In the electronic apparatus 10, the output of the booster circuit 102 is connected to the output line of the step-down SW regulator 120 via a Zener diode D138 and a diode D140. The breakdown voltage of the Zener diode D138 is, for example, a value (for example, 40V) of a predetermined output voltage (step-up voltage) of the booster circuit 102 and a value (for example, 7V) of a predetermined output voltage (step-down voltage) of the step-down SW regulator 120. (For example, 33V (= 40V-7V)).

As a result, in the electronic device 10, for example, the CPU 100 turns on the relay RL 116 to cause a current to flow from the power supply device 150 to the starter motor 152 that is a large current load. Voltage) Even when V _BAT decreases and the output voltage of the step-down SW regulator 120 decreases, charge flows from the output capacitor C112 of the step-up circuit 102 to the output capacitor C134 of the step-down SW regulator 120 via the Zener diode D138, and The step-down voltage is ensured. For this reason, the CPU 100 can stably continue the control process to be performed when the starter motor 152 is driven without being affected by fluctuations in the power supply voltage V _BAT of the power supply device 150.

  In particular, in the present electronic device 10, the power supply circuit that generates the operating voltage for the CPU 100 from the power supply device 150 has a two-stage configuration as described above, and the output line of the booster circuit 102 is connected to an external power supply device (for example, Rather than being directly connected to the power supply line from the vehicle battery), it is connected to the output line of the step-down SW regulator 120 which is the first stage power supply circuit.

  Therefore, in the electronic device 10, the charge of the output capacitor C112 of the booster circuit 102 flows only to the output capacitor C134 connected to the output line of the step-down SW regulator 120 and the second-stage power supply circuits 122 to 126, and the like. No load (for example, the starter motor 152) flows. For this reason, in the present electronic device 10, the amount of charge flowing out from the output capacitor of the booster circuit to the other power supply line is increased as in the conventional case, and the output voltage (boost voltage) of the booster circuit is greatly reduced. Therefore, the operation of the device driven by the boosted voltage (for example, the above-described solenoid valve (not shown) driven by the solenoid valve drive circuit 104) is kept stable.

  In the electronic apparatus 10, the output line of the booster circuit 102 is not connected between another power supply circuit and a load (for example, CPU) of the power supply circuit, as in the prior art. Is connected to the output line of the step-down SW regulator 120, which is the power circuit of the first stage, and the operating voltage to the CPU 100 is stably secured by the power circuits 122, 124, 126 of the second stage. For this reason, in this electronic device 10, even if there is a temperature variation in the breakdown voltage of the Zener diode D138, the operating voltage supplied to the CPU 100 is stably maintained, and the stable operation of the CPU 100 is ensured. The diode D140 is provided to prevent the charge of the output capacitor C134 of the step-down SW regulator 120 from being discharged to the output line of the booster circuit 102.

Furthermore, the electronic device 10 includes a first monitor voltage V _MON1 resistors constituting the voltage dividing circuit for inputting generated by the CPU100 of R142, R144 proportional to the output voltage of the booster circuit 102, power supply 150 Resistors R146 and R148 constituting a voltage dividing circuit for generating and inputting a second monitor voltage _VMON2 proportional to the output voltage (power supply voltage) V _BAT of the second monitor voltage _VMON2 .

As a result, the CPU 100 monitors fluctuations in the boosted voltage of the booster circuit 102 and fluctuations in the power supply voltage of the power supply device 150 using the first and second monitor voltages V _MON1 and V _MON2 , and the power supply voltage becomes a predetermined value or less. When the power supply voltage is lowered to a predetermined value or lower and the boosted voltage is also lowered to a predetermined value or lower, the power consumption on the output line side of the power supply circuits 122, 124, 126 is reduced and the booster circuit 102 is reduced. The amount of charge flowing from the output line to the output line of the step-down SW regulator 120 is reduced.

For example, when the output voltage V _BAT of the power supply device 150 is caused by driving of the starter motor 152 when starting the internal combustion engine, the reduction of the power consumption of the power supply circuits 122, 124, 126 is performed by the internal combustion engine. Stop control of devices other than devices required for starting (starter motor 152, solenoid valve (not shown), etc.) to reduce power consumption of 5V power supply (power supply circuit 122) and / or 3.3V power supply (power supply circuit 124) Alternatively, the CPU core (not shown) of the CPU 100 can be set to the low power consumption mode to reduce the power consumption of the 1.5V power supply (power supply circuit 126).

  As described above, in the electronic apparatus 10 according to the present embodiment, the operation voltage supplied to a device (for example, the CPU 100) that needs to supply a stable operation voltage is a two-stage operation using the step-down SW regulator 120 as the first stage. The output line of the booster circuit 102 that boosts and outputs the voltage supplied from the external power supply device 150 and supplied from the power supply circuit having the configuration is a step-down SW that is the first-stage power supply circuit via the Zener diode D138. It is connected to the output line of the regulator 120.

  As a result, the electronic device 10 can reduce or avoid fluctuations in the boost voltage by limiting the amount of charge flowing out from the boost circuit 102 to another power supply circuit, and can also influence the influence of temperature fluctuations in the breakdown voltage of the Zener diode. A constant operating voltage can be supplied to the CPU 100 without receiving it and the operation can be kept stable.

In the present embodiment, the power supply circuit of the first stage is the step-down SW regulator 120. However, the present invention is not limited to this, and other SW regulators (for example, a step-up / step-down switching regulator or other types of power supply circuits) can be used. The same effect can be obtained. Further, the second stage power supply circuits 122, 124, 126 all supply the operating voltage to the CPU 100. However, the present invention is not limited to this, and the number of power supply circuits included in the second stage may be one. In addition to the power supply circuits 122, 124, and 126, a power supply circuit that supplies an operating voltage to a device other than the CPU 100 can be included. In the latter case, CPU 100, when the power supply voltage by V _MON1, V _MON2 is judged to have decreased below a predetermined value, or a power supply voltage is judged to have decreased and the boosted voltage below a predetermined value drops below a predetermined value In this case, the operation of the devices other than the CPU 100 is stopped to reduce the power consumption of the entire second stage power supply circuit, and the amount of charge flowing from the output line of the booster circuit to the output line of the step-down SW regulator 120 (or Current) can be limited.

  DESCRIPTION OF SYMBOLS 10 ... Electronic device, 100 ... CPU, 102 ... Booster circuit, 104 ... Solenoid valve drive circuit, L106, L128 ... Coil, Tr108, Tr130 ... Transistor, D110, D132, D140 ... Diode, D138 ... Zener diode, C112, C134 ... Output capacitor, 114 ... Boost control circuit, RL116 ... Relay, 118 ... Switch circuit, 120 ... Step-down SW regulator, 122, 124, 126 ... power supply circuit, 136 ... step-down control circuit, R142, R144, R146, R148 ... resistor, 150 ... power supply device, 152 ... starter motor.

Claims (5)

A first power supply circuit that converts a power supply voltage supplied from a power supply device into a first voltage and outputs the first voltage;
A second power supply circuit that converts a power supply voltage supplied from the power supply device into a second voltage and outputs the second voltage;
At least one third power supply circuit that operates in response to the supply of the second voltage output from the second power supply circuit;
With
An output of the first power supply circuit is connected to an output line of the second power supply circuit from the second power supply circuit to the third power supply circuit via a constant voltage diode;
Electronic equipment. Further comprising a processing device;
The processing device operates by receiving an operating voltage from at least one third power supply circuit,
The first power supply circuit supplies an operating voltage of a device operating under the control of the processing apparatus;
The electronic device according to claim 1. The first power supply circuit is a booster circuit;
The device is a solenoid valve that regulates the fuel supply of an internal combustion engine of a vehicle.
The electronic device according to claim 2. The processing device monitors a power supply voltage output from the power supply device and a first voltage output from the first power supply circuit, and when the power supply voltage drops below a predetermined value or when the power supply voltage is predetermined. Operates to limit the load current of the third power circuit when the first voltage drops below a predetermined value
The electronic device according to claim 2. The limitation of the load current of the third power supply circuit is that the processing device stops the operation of a part of the device to which the operating voltage is supplied by the third power supply circuit and / or the processing device operates itself. Done by setting the mode to low power consumption mode,
The electronic device according to claim 4.

Images