JPH05127765A - Power supply unit for on-vehicle electronic device - Google Patents

Abstract

PURPOSE:To save, specially, a space and improve a heat radiation measure as to the power supply unit for the on-vehicle electronic device which supplies electric power to plural electronic control circuits differing in ground potential. CONSTITUTION:This power unit is equipped with a switching regulator 11 which is supplied with the electric power from a DC power source +B, and circuits 1, 2... constituting the electronic devices are applied with voltages which are proper about the ground potentials of the respective circuits from the switching regulator 11 through series regulators 121, 122.... The voltages from the respective series regulators 121, 122... are fed back to the measuring circuit 114 of the switching regulator 11 and the voltage of the highest potential is detected among them; and a control circuit 113 controls a transistor 111 according to the detected voltage and the switching regulator 11 outputs a voltage corresponding to the highest voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for an on-vehicle electronic device which supplies power of an appropriate voltage to a plurality of electronic control devices mounted on a vehicle and having different ground potentials. Regarding

[0002]

2. Description of the Related Art In a vehicle equipped with an engine, an electronic control unit for controlling fuel injection of the engine,
Various types of electronic devices such as an electronic control device that controls an air conditioner installed in a vehicle are installed. For these electronic devices, a power supply device that generates an appropriate voltage is required for each electronic device, and a DC power supply from a vehicle-mounted battery is connected to these power supply devices. There is.

A voltage of 5 V, for example, is generated by a series regulator for each of these electronic devices. However, in order to save space, reduce the size of the on-vehicle electronic control device, and share the components, it is conceivable to integrate a plurality of power supply devices set corresponding to each electronic device.

However, considering the electronic devices mounted on such a vehicle, these electronic devices operate based on different ground potentials from the engine ground type, the body ground type, and the like. Therefore, the ground potentials of the plurality of electronic devices cannot be the same ground potential.

Further, when the power source of each electronic control unit is constituted by only the series regulator, each series regulator drops the potential (for example, 5 V) required by the corresponding electronic control unit, and therefore each series. A large amount of heat is generated in the regulator, and measures to dissipate the heat become a big problem. In addition, the efficiency of power supply is also reduced.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and makes it possible to ensure the power supply efficiency of a series regulator which is set corresponding to each of a plurality of electronic devices. An object of the present invention is to provide a power supply device for an on-vehicle electronic device that can reduce the amount of heat radiation in each series regulator and can be shared by a plurality of electronic devices.

[0007]

A power supply device for an on-vehicle electronic device according to the present invention comprises a plurality of switching regulators for stepping down a voltage from a DC power supply such as a battery, and a plurality of voltages generated from the switching regulators. A plurality of series regulators set corresponding to each of the electronic device, the switching regulator, the power supply voltage generated in each of the plurality of series regulators, the ground potential of the DC power supply as a reference. And includes a measuring means to detect the highest voltage,
The maximum voltage measured by this measuring means is generated by the switching regulator.

[0008]

In the power supply device configured as described above, the voltage of the highest potential required by each electronic device is generated in the switching regulator with reference to the ground potential of the DC power supply, and this voltage is generated by each switching device. Supplied to the series regulator. Therefore, in each series regulator, an appropriate voltage required by each electronic device is generated by stepping down by the difference between the ground potential of the corresponding electronic device and the ground potential of the DC power supply. Since the amount of heat generated by the regulator can be minimized, the heat dissipation mechanism, etc., can be sufficiently simplified and configured, and a great effect is achieved in saving space, and good power supply efficiency can be secured. become.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In this embodiment, a plurality of circuits 1, 2 ... With different ground potentials exist as electronic devices, and the power supplied to each of these electronic devices is constituted by a single circuit. It shows an example.

FIG. 1 shows the configuration thereof, in which a DC voltage + B from an on-vehicle DC power source such as a battery (not shown) is supplied to the switching regulator 11. The ground potential GND of the switching regulator 11 is matched with the ground potential of the battery. Then, in this switching regulator 11, the DC voltage + B from the battery is stepped down to a voltage Vsw corresponding to the voltage used in the vehicle electronic device with high efficiency.

When the voltage from the battery or the like is stepped down by the switching regulator 11 to the voltage used in each electronic device, the efficiency is higher than that of the series regulator, and accordingly, less heat is generated and a heat radiation measure is taken. It can be simplified and configured.

The voltage of the voltage Vsw generated by the switching regulator 11 is a plurality of series regulators 12
, Which are supplied in parallel to each of the series regulators 121, 122, ..., The output voltage from each of the series regulators 121, 122 ,. To be supplied as power source.

The series regulators 121, 122, ...
In the above, the voltage stepped down by the switching regulator 11 is stepped down to the voltage required by each circuit,
Therefore, the voltage ratio to be stepped down can be reduced as compared with the case where the power supply is configured by only the series regulator. So this each series regulator
Each of the series regulators 121, 122, ...
… The heat radiation measures in each can be simplified.

The output from the switching regulator 11 is inadequate in terms of noise level for a device such as an A / D converter that requires voltage accuracy. Therefore, in this power supply device, the output voltage from the switching regulator 11 is supplied to the plurality of series regulators 121, 122, ...
A stable power supply voltage of, for example, 5 V is supplied to ...

In this way, by configuring the series regulators 121, 122, ... Corresponding to each circuit between the switching regulator 11 and each circuit, each circuit 1, circuit 2 ,. A current limiter can be provided for each. Therefore, each of these circuits 1, 2, ...
Assuming that one of the two is destroyed and an overcurrent flows in that circuit, the effect of this overcurrent will not be exerted on other circuits, and the current limit can be controlled only for that destroyed circuit. Becomes

The output voltage of each switching regulator 121, 122, ... Is switched when the ground potential differs between the circuit 1, circuit 2, ... To which power is supplied from each of the series regulators 121, 122 ,. Feedback to regulator 11.

FIG. 2 shows a specific circuit example of the switching regulator 11. The input voltage of + B is led to the output through the transistor 111 and the rectifier circuit 112 which are switching-controlled. Transistor 111 is the control circuit
On / off control is performed at a predetermined duty based on a command signal from 113, and a DC output voltage Vsw corresponding to this on / off duty can be obtained. Then, the control circuit 113 causes a command to be given from the measuring circuit 114 to which the feedback voltage is supplied from each circuit.

FIG. 3 shows a circuit example of the measuring circuit 114, in which the voltage supplied to each of the circuits 1 to 3 is supplied and the voltage of the highest value is supplied to the control circuit 13. ..

In this case, the ground potentials of the circuits 1 to 3 are different as indicated by GND1, GND2, and GND3, respectively. Therefore, even if each circuit operates at 5V, the DC power supply When the ground potential GND is used as a reference, the voltages output from the series regulators 121, 122, ... Are different. Specifically, the highest output voltage is required in the series regulator 113 that supplies power to the circuit 3 having the highest ground potential β in FIG.

As shown in FIG. 4, when the ground potential is different in each circuit, the series regulator 121
, 122, ... If the output voltage from each of them is not fed back to the switching regulator 11, the voltage Vsw output from the switching regulator 11 becomes the same voltage as seen from the ground potential GND of the DC power source by the battery.

Assuming that the output voltage from the switching regulator 11 is Vsw1 (= 5V + α), if the ground potential GND3 of the circuit 3 is higher than the ground potential GND of the switching regulator 11 by α or more, the series regulator 121, 122, ... Ground potential (GND1
It is not possible to create a 5V voltage for ~ GND3).

In particular, in the series regulator 123 for supplying power to the circuit 3, the ground potential GND of the DC power source and the ground potential GND3 of the circuit 3 are β larger than α, so the switching regulator 11 outputs Voltage V
If sw1 is generated, the power supply voltage of 5V cannot be set for the circuit 3.

However, in the device shown in the embodiment,
Series regulator 121 to circuit 1 to circuit 3 for the measuring circuit 114 of the switching regulator 11
The output voltage from 123 is fed back. And
In the measurement circuit 114, the voltage of the circuit 3, which is the highest voltage among the feedback voltages when viewed from the ground potential GND of the DC power supply in each series regulator 121 to 123, is measured and detected, and this voltage is supplied to the control circuit 113. The switching regulator 11 outputs the voltage Vsw2 corresponding to this measured detection voltage.

That is, this switching regulator
In FIG. 11, the voltage Vsw2 higher than the ground potential GND of the DC power source by the increase β of the ground potential GND3 of the circuit 3 is output. In each of the series regulators 121, 122, ... 2, ... It becomes possible to generate a power supply voltage of 5 V for each ground potential.

In this case, the series regulators 121, 12
2, ... Circuit 1, circuit 2, to which power is supplied from each
When the difference between the ground potentials is small, the output voltage Vsw from the switching regulator 11 is set to “Vsw
By setting “= (5V + α)”, a waste voltage is not generated, and an effect of power saving can be exerted.

FIG. 5 shows the flow of control for executing the above control. In step 201, the feedback voltage which is the output voltage from each of the series regulators 121, 122, ... Is input, and in step 202. For example, it is determined whether the reference voltage “Vsw = (5V + α)” is lower than the feedback voltage. Then, when it is determined that the reference voltage is higher than the feedback voltage, the process returns to step 201. On the contrary, when it is determined that the feedback voltage is higher than the reference voltage, the process proceeds to the next step 203 to make the reference voltage match the feedback voltage.

[0027]

As described above, according to the power supply device for the on-vehicle electronic device of the present invention, by connecting the switching regulator and the series regulator in series,
Electric power can be efficiently supplied to a plurality of circuit systems having different ground potentials. Even if there is a difference in the ground potential in each circuit system, the voltage supplied from the switching regulator to each series regulator is fed back to the switching regulator by feeding back the output from the series regulator corresponding to each circuit system. Is controlled so that a stable and appropriate voltage can be supplied from each series regulator to each circuit system. In this case, since the step-down rate in each series regulator can be made sufficiently small, the problem of heat generation countermeasure can be surely improved, and a great effect can be achieved in saving space.

[Brief description of drawings]

FIG. 1 is a configuration diagram illustrating a power supply device of an in-vehicle electronic device according to an embodiment of the invention.

FIG. 2 is a diagram showing a configuration of a switching regulator of the above embodiment.

FIG. 3 is a circuit diagram showing an example of a measurement circuit that constitutes this switching regulator.

FIG. 4 is a diagram illustrating a relationship between a voltage fed back to the measurement circuit and an output voltage from a switching regulator.

FIG. 5 is a flowchart illustrating a flow of feedback control of a switching regulator.

[Explanation of symbols]

11 ... Switching regulator, 111 ... Transistor,
112 ... Rectifier circuit, 113 ... Control circuit, 114 ... Measuring circuit, 121
, 122,… Series regulator.

Claims (1)

[Claims] 1. A switching regulator to which a direct current voltage is supplied from a direct current power source and an output voltage from this switching regulator are respectively supplied and set corresponding to each of a plurality of electronic devices. A plurality of series regulators that generate a predetermined required voltage based on the ground potential, the switching regulator, in the power supply voltage generated in each of the plurality of series regulators,
It is configured to include a measuring means for detecting the highest voltage with reference to the ground potential of the DC power source, and a DC voltage corresponding to the highest potential measured by the measuring means is supplied to each of the series regulators. A power supply device for an on-vehicle electronic device, comprising: