JP4341156B2 - Vehicle power supply - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicular power supply apparatus that supplies power to a load control circuit from a power supply line connected to an in-vehicle battery, in particular, when the output voltage of the in-vehicle battery temporarily decreases, The present invention relates to a vehicle power supply device that is backed up by a charge.
[0002]
[Problems to be solved by the invention]
In recent vehicles, many load control circuits are mounted for controlling various loads, and such load control circuits are generally composed mainly of computers. In this case, the power of the load control circuit is supplied from the in-vehicle battery through the power supply line, but the output voltage of the in-vehicle battery is temporarily lowered for a relatively long time, such as when the engine starter is operating. For this reason, there is a possibility that a load control circuit mainly composed of a computer malfunctions due to a temporary decrease in power supply voltage.
[0003]
Therefore, in the conventional vehicle power supply device, a capacitor is connected to the power supply line, and the output voltage of the power supply line is backed up by the charge of the capacitor when the output voltage of the in-vehicle battery temporarily decreases. And that is done. In this case, when the output voltage of the power supply line becomes lower than a preset reference voltage, the current consumption is suppressed by switching the load control circuit from the normal operation mode to the low power consumption mode. However, even in this case, it is difficult to sufficiently reduce the current consumption at the time of power backup by the capacitor. Therefore, the current consumption is reduced by increasing the circuit impedance. However, when the circuit impedance is increased in this way, it is easily affected by external noise, and the operation of the load control circuit may become unstable. This is an unsolved problem. .
[0004]
The present invention has been made in view of the above circumstances, and an object of the present invention is to sufficiently reduce the current consumption at the time of power backup by a capacitor and to eliminate the possibility of unstable operation of a load control circuit to be supplied with power. The object is to provide a vehicle power supply device.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the means described in claim 1 can be employed. According to this means, when the output voltage of the power supply line connected to the in-vehicle battery temporarily decreases, the output voltage of the power supply line is backed up by the capacitor. During this backup operation, the charge of the capacitor is charged. As the battery discharges, the output voltage of the power supply line gradually decreases. In response to such a voltage drop, when the detection voltage by the resistance voltage dividing circuit becomes lower than a preset reference voltage, the backup control circuit switches the load control circuit from the normal operation mode to the low power consumption mode. Become. Further, during the period when the load control circuit is switched to the low power consumption mode in this way, the operation control means turns on and off the switching circuit intermittently. Then, when the switching circuit is in the on state, the output voltage of the power supply line is supplied to the resistance voltage dividing circuit, and when the switching circuit is in the off state, the voltage supply is cut off . That is, since the current is intermittently supplied to the resistance voltage dividing circuit, the average current consumption in the resistance voltage dividing circuit is suppressed as a result.
[0006]
Thereafter, when the detection voltage of the resistance voltage dividing circuit becomes equal to or higher than the reference voltage in the period in which the switching circuit is in the on state, that is, in the period in which the output voltage of the power supply line is supplied to the resistance voltage dividing circuit, The backup control circuit controls the load control circuit to return to the normal operation mode, and the operation control means holds the switching circuit in the ON state, thereby temporarily reducing the output voltage of the power supply line. It will come back to the previous state.
[0007]
As described above, when the power supply is backed up by the capacitor, the load control circuit is switched to the low power consumption mode and the current consumption in the resistance voltage dividing circuit is suppressed. The current can be sufficiently reduced, and as a result, there is no need to increase the circuit impedance as in the conventional configuration, and there is no possibility that the operation of the load control circuit becomes unstable due to the influence of external noise. .
[0008]
In this case, the means described in claim 2 can be employed. According to this means, when the power supply backup state by the capacitor is entered, when the detection voltage by the resistance voltage dividing circuit becomes lower than the reference voltage, that is, when the load control circuit is switched to the low power consumption mode, the backup control circuit However, since the switching element is turned off and the main power supply of the load control circuit is cut off, only the control power supply is supplied from the constant voltage power supply circuit to the load control circuit. As a result, the effect of suppressing current consumption in the load control circuit can be enhanced. At this time, the backup control circuit instructs the load control circuit to interrupt the normal operation mode and store the data necessary for returning to the normal operation mode in the storage means. Therefore, the operation of the load control circuit after the output voltage of the power supply line returns to the normal state is guaranteed.
[0009]
According to the third aspect of the present invention, when the power supply backup state by the capacitor, that is, when the switching circuit is intermittently turned on / off, the resistance voltage dividing circuit and the reference voltage are generated in the off period. Since the voltage supply to the voltage generation circuit is cut off at the same time, it is possible to sufficiently exhibit the current consumption suppression effect associated with the intermittent on / off of the switching circuit.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In FIG. 1 showing the overall circuit configuration, the vehicle control circuit unit 1 has a power terminal + V connected to a plus power terminal of the in-vehicle battery 2 and a ground terminal GND grounded. The negative source terminal of the in-vehicle battery 2 is also grounded. The control circuit unit 1 is incorporated, for example, in an in-vehicle information processing apparatus (such as a car navigation apparatus), and has the following configuration.
[0011]
That is, in the control circuit unit 1, the power supply terminal + V forwards the diode 3 for the reverse connection countermeasure (for the circuit element protection countermeasure when the control circuit unit 1 is erroneously connected to the in-vehicle battery 2 in the reverse polarity state). Is connected to the power supply line 4. The power supply line 4 is connected to the input side of a stabilized power supply IC 5 (corresponding to a constant voltage power supply circuit in the present invention), and a voltage output at a constant level is supplied from the power supply IC 5 to the auxiliary power supply line 6. It has become.
[0012]
A computer main circuit 7 (corresponding to a load control circuit) for controlling the operation of the in-vehicle information processing apparatus is configured to include a CPU, a ROM, a RAM, etc. (none of which are shown). Power is supplied from the auxiliary power line 6 and main power for driving the load to be controlled is supplied from the power line 4 via a gate control type switching element 8 (for example, MOSFET). Yes.
[0013]
A power backup capacitor 9 is connected between the power line 4 and the ground terminal GND. When the output voltage of the in-vehicle battery 2 temporarily decreases according to the operation of the engine starter or the like, The output voltage is backed up by the charge of the capacitor 9.
[0014]
When the output voltage of the power supply line 4 drops below a predetermined level, the voltage detection circuit 10 shuts off the main power supply of the computer main circuit 7 and switches the computer main circuit 7 to the low power consumption mode. When the output voltage of the power supply line 4 returns to a steady state, the main power supply of the computer main circuit 7 is provided and the operation for releasing the low power consumption mode is performed. 10 will be described.
[0015]
That is, in the voltage detection circuit 10, the first voltage dividing circuit 11 (corresponding to a resistance voltage dividing circuit) is composed of a series circuit of resistors 11 a and 11 b, and one end of the first voltage dividing circuit 11 is connected between the emitter and collector of the pnp transistor 13. The other end side is connected to the ground terminal GND. Thereby, in the first voltage dividing circuit 11, the detection voltage V1 corresponding to the output voltage level of the power supply line 4 is output from the common connection point of the resistors 11a and 11b in the ON state of the transistor 13.
[0016]
The second voltage dividing circuit 12 (corresponding to a voltage generating circuit) is composed of a series circuit of resistors 12a and 12b, and one end of the second voltage dividing circuit 12 is connected to the auxiliary power line 6 via the emitter and collector of the pnp transistor 14. The other end side is connected to the ground terminal GND. Thereby, in the second voltage dividing circuit 12, the reference voltage V2 of a preset level is output from the common connection point of the resistors 12a and 12b in the ON state of the transistor 14.
[0017]
In this case, the detection voltage V1 and the reference voltage V2 have a relationship of V1 ≧ V2 when the output voltage of the power supply line 4 is higher than a preset threshold voltage Vth, and the output voltage of the power supply line 4 has the threshold. Adjustment is made so as to exhibit the relationship of V1 <V2 when the value voltage is equal to or lower than Vth.
[0018]
The transistors 13 and 14 together with the npn transistor 15 form a switching circuit 16 referred to in the present invention. In the switching circuit 16, the bases of the transistors 13 and 14 are individually connected to the collector of the transistor 15 via the resistors 13a and 14a, and the emitter of the transistor 15 is connected to the ground terminal GND. Is connected to the output terminal of the OR circuit 17 through a resistor 15a.
[0019]
The comparison circuit 18 provided so as to be fed from the auxiliary power supply line 6 receives the detection voltage V1 from the first voltage dividing circuit 11 at its non-inverting input terminal (+), and the inverting input terminal (−). Are connected to receive the reference voltage V2 from the second voltage dividing circuit 12. The output terminal of the comparison circuit 18 is connected to a data terminal D of a latch circuit 19 made of, for example, a level trigger type D flip-flop.
[0020]
The latch circuit 19 is provided so that power is supplied from the auxiliary power supply line 6. When the enable terminal G is at "H" level, the input signal of the data terminal D is directly output from the output terminal Q, and the enable terminal G When G becomes “L” level, a known operation is performed to latch the output from the output terminal Q at that time. The latch circuit 19 has an enable terminal G connected to the output terminal of the OR circuit 17 and an output terminal Q connected to the signal input terminal P 1 of the backup control circuit 20.
[0021]
The backup control circuit 20 is provided so as to be supplied with power from the auxiliary power line 6 and outputs a gate signal from the output terminal Q1 when the input signal level of the signal input terminal P1 is “H”. The switching element 8 is held in the ON state, and the “H” level signal is output from the output terminals Q2 and Q3. A signal from the output terminal Q2 is applied to one input terminal of the OR circuit 17, and a signal from the output terminal Q3 is applied to the computer main circuit 7. Further, when the level of the input signal at the signal input terminal P1 is inverted to “L”, the backup control circuit 20 inverts the output signals from the output terminals Q2 and Q3 to “L” level, and in this state, the input terminal When a power-off command signal is input from the computer main circuit 7 to P2, the output of the gate signal from the output terminal Q1 is stopped and the switching element 8 is turned off. The “L” level signal output from the output terminal Q3 corresponds to the backup operation command in the present invention.
[0022]
In this case, the computer main circuit 7 has a normal operation mode in which an active state is exhibited and a normal control operation is executed during a period in which the “H” level signal is applied from the output terminal Q3 of the backup control circuit 20. Is held, but when the signal is inverted to "L" level (when a backup operation command is output), the normal operation mode is interrupted and the data necessary for returning to the normal operation mode Is stored in the RAM, and when the backup operation is completed, the power-off command signal is supplied to the input terminal P2 of the backup control circuit 20.
[0023]
As described above, the OR circuit 17 receives a signal from the output terminal Q2 of the backup control circuit 20 at one input terminal, while the other input terminal receives an oscillation circuit 21 (corresponding to an operation control means). ) Is received. For example, as shown in FIG. 2, the pulse signal Sp has a pulse width τ of, for example, about 100 milliseconds and a period T of, for example, 1 to several seconds (or 1 to several tens of seconds). Although the connection relationship is not shown, power for the OR circuit 17 and the oscillation circuit 21 is supplied from the auxiliary power line 6.
[0024]
Next, the operation of the circuit configuration described above will be described with reference to the timing chart of FIG. 2 showing the voltage waveforms and states of each part.
Now, in a steady state where an “H” level signal is output from the output terminal Q of the latch circuit 19, the backup control circuit 20 that has received the “H” level signal at the input terminal P 1 holds the switching element 8 in the ON state. Therefore, the main power supply of the computer main circuit 7 is supplied from the power supply line 4 via the switching element 8. At this time, since the “H” level signal is output from the output terminals Q 2 and Q 3 of the backup control circuit 20, the computer main circuit 7 receives the “H” level signal from the output terminal Q 3 of the backup control circuit 20. Thus, an active state, that is, a normal operation mode for executing a normal control operation is held.
[0025]
Further, since the “H” level signal from the output terminal Q2 of the backup control circuit 20 is given to the enable terminal G of the latch circuit 19 via the OR circuit 17, the latch circuit 19 receives the input signal of the data terminal D. In this state, the signal is output from the output terminal Q as it is, and since the “H” level signal is applied to the base of the transistor 15 via the OR circuit 17 and the resistor 15a, the transistor 15 is turned on. Transistors 13 and 14 corresponding to the first voltage dividing circuit 11 and the second voltage dividing circuit 12 are turned on. In response to such ON, the detection voltage V1 and the reference voltage V2 are output from the first voltage dividing circuit 11 and the second voltage dividing circuit 12, respectively.
[0026]
In this case, when the output voltage of the power supply line 4 is at a steady level (a level equal to or higher than the aforementioned threshold voltage Vth), the detection voltage V1 from the first voltage dividing circuit 11 and the voltage from the second voltage dividing circuit 12 are output. Since the reference voltage V2 exhibits a relationship of V1 ≧ V2, the “H” level signal is output from the comparison circuit 18, and the steady state described above is maintained accordingly. In this steady state, the capacitor 9 is charged to a voltage level corresponding to the output voltage of the in-vehicle battery 2.
[0027]
From such a steady state, when the output voltage of the in-vehicle battery 2 temporarily decreases in accordance with the operation of the engine starter or the like, the output voltage of the power supply line 4 is backed up by the charge of the capacitor 9, but the discharge As the process proceeds, the output voltage of the power supply line 4 gradually decreases. Accordingly, when the output voltage of the power supply line 4 becomes lower than a preset threshold voltage Vth, the detection voltage V1 and the reference voltage V2 have a relationship of V1 <V2, and therefore the output of the comparison circuit 18 is “L”. Invert to level. Then, since the latch circuit 19 receiving the “L” level signal at the data terminal D outputs the “L” level signal as it is from the output terminal Q, the backup control circuit 20 receiving this at the input terminal P1 The output signals from the output terminals Q2 and Q3 are inverted to the “L” level.
[0028]
In this case, the computer main circuit 7 that has received the "L" level signal from the output terminal Q3 interrupts the normal control operation and stores data necessary for resuming the control operation in the RAM. When the operation is performed and the backup operation is completed, the power cut command signal is given to the input terminal P2 of the backup control circuit 20, and then the mode is shifted to the low power consumption mode (sleep state). Thus, since the backup control circuit 20 which has received the power-off command signal to the input terminal P2 is, turns off the switching elements 8 to stop the output of the gate signal from the output terminal Q 1, computer main circuit 7 is mainly The power supply is cut off and the state is switched to the state where only the control power supply is supplied.
[0029]
Further, since the output from the output terminal Q2 of the backup control circuit 20 is inverted to the “L” level, the pulse signal Sp from the oscillation circuit 21 is activated, and the pulse signal Sp passes through the OR circuit 17. And is intermittently applied to the enable terminal G of the latch circuit 19 and to the base of the transistor 15 via the OR circuit 17 and the resistor 15a.
[0030]
Therefore, in the latch circuit 19, the comparison output from the comparison circuit 18 is output from the output terminal Q during the period when the pulse signal Sp rises, and at the falling timing during the period when the pulse signal Sp falls. The output will be latched. Further, since the transistor 15 is intermittently turned on at intervals corresponding to the output period of the pulse signal Sp, each transistor 13 corresponding to the first voltage divider circuit 11 and the second voltage divider circuit 12 is turned on. And 14 are intermittently turned on, and the detection voltage V1 and the reference voltage V2 from the voltage dividing circuits 11 and 12 are output only during the rising period of the pulse signal Sp. As a result, the comparison operation by the comparison circuit 18 and the comparison result output operation of giving the comparison result to the backup control circuit 20 are relatively short time (100 m) corresponding to the pulse width τ of the pulse signal Sp as shown in FIG. It is in a valid state only for about 2 seconds), and is invalidated for other periods.
[0031]
Thereafter, when the state in which the output voltage of the in-vehicle battery 2 temporarily decreases is resolved, the detection voltage V1 and the reference voltage V2 return to the relationship of V1 ≧ V2 during the ON period of the transistor 15, and therefore the comparison circuit 18 Since the “H” level signal is output from the comparator circuit 18 and the “H” level signal is applied to the enable terminal of the latch circuit 19 during the ON period of the transistor 15. The “H” level signal is output as it is from the output terminal Q of the latch circuit 19. Then, the backup control circuit 20 receiving the “H” level signal returns the switching element 8 to the ON state and returns to the state where the “H” level signal is output from the output terminals Q2 and Q3. As a result, the computer main circuit 7 is returned to the normal operation mode (active state) supplied with the main power.
[0032]
In short, according to the configuration of the present embodiment described above, when the output voltage of the power supply line 4 temporarily decreases, the output voltage of the power supply line 4 is backed up by the charge of the capacitor 9, and in this backup state, the computer The switching element 8 for supplying the main power to the main circuit 7 is forcibly turned off, and the computer main circuit 7 in the normal operation mode is on standby with data necessary for resuming the control operation being stored in the RAM. The mode is switched to the power consumption mode, thereby suppressing the entire current consumption and extending the power backup time by the charge of the capacitor 9.
[0033]
In this case, the power consumption of the resistors 11a, 11b and 12a and 12b in the first voltage dividing circuit 11 and the second voltage dividing circuit 12 is relatively large, and therefore the resistors 11a, 11b and 12a 12b, it is difficult to suppress the current consumption of the entire circuit to about 1 mA or less at the time of power backup. On the other hand, in this embodiment, in the power backup state by the capacitor 9, the transistors 13 and 14 corresponding to the first voltage dividing circuit 11 and the second voltage dividing circuit 12 are turned on intermittently, Since the average current consumption in the resistors 11a, 11b and 12a, 12b is suppressed, the current consumption of the entire circuit can be reduced to less than 1 mA. As a result, the capacitor 9 is charged. It will be possible to further extend the power backup time due to electric charges. In addition, since it is possible to reduce the overall current consumption in the power backup state without changing the circuit impedance of the control circuit unit 1, it is not necessary to increase the circuit impedance as in the conventional configuration, and the computer main circuit 7 This eliminates the possibility of the operation becoming unstable due to the influence of external noise. In this case, the current consumption in the resistors 11a, 11b and 12a, 12b is determined by the duty ratio of the pulse signal Sp from the oscillation circuit 21, but the duty ratio may be reduced as much as possible. Instead, the pulse width τ and the period T of the pulse signal Sp that determines the duty ratio are set within a range in which the comparison operation in the comparison circuit 18 is reliably performed.
[0034]
Further, the backup control circuit 20 gives a backup operation command for instructing the computer main circuit 7 to interrupt the normal operation mode and store the data necessary for returning to the normal operation mode in the RAM. As a result, the operation of the computer main circuit 7 after the output voltage of the power supply line 4 returns to a normal state is guaranteed. Further, when the power source is backed up by the capacitor 9, that is, when the switching circuit 16 is intermittently turned on / off, voltage supply to the first voltage dividing circuit 11 and the second voltage dividing circuit 12 is performed during the off period. Are interrupted at the same time, so that the effect of suppressing current consumption associated with intermittent on / off of the switching circuit 16 can be sufficiently exhibited.
[0035]
The present invention is not limited to the above-described embodiment, and the following modifications or expansions are possible.
As the switching element 8, not only a MOSFET but also a bipolar transistor or IGBT can be used. The oscillation circuit 21 can be formed by a CMOS circuit element, and its power consumption can be made extremely small. Therefore, the oscillation circuit 21 may be always operated. For example, the output terminal Q2 of the backup control circuit 20 may be used. It is also possible to operate only during a period in which the output from is inverted to the “L” level.
[Brief description of the drawings]
FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention. FIG. 2 is a timing chart for explaining an operation.
1 is a control circuit unit, 2 is an in-vehicle battery, 4 is a power supply line, 5 is a stabilized power supply IC (constant voltage power supply circuit), 6 is an auxiliary power supply line, 7 is a computer main circuit (load control circuit), 8 is a switching element , 9 is a capacitor, 10 is a voltage detection circuit, 11 is a first voltage dividing circuit (resistance voltage dividing circuit), 12 is a second voltage dividing circuit (voltage generating circuit), 16 is a switching circuit, 18 is a comparison circuit, Reference numeral 19 denotes a latch circuit, 20 denotes a backup control circuit, and 21 denotes an oscillation circuit (operation control means).

Claims (3)

Power is supplied to the load control circuit from the power line connected to the in-vehicle battery, and the output voltage of the power line is backed up by the charge of the capacitor when the output voltage of the in-vehicle battery temporarily decreases,
A resistance voltage dividing circuit for detecting an output voltage of the power supply line, and when the detection voltage by the resistance voltage dividing circuit becomes lower than a preset reference voltage, the load control circuit is changed from a normal operation mode to a low power consumption mode. In a vehicle power supply device comprising a backup control circuit for switching to
A switching circuit that supplies an output voltage of the power supply line to the resistance voltage dividing circuit in an on state and cuts off the voltage supply in an off state;
Wherein with load control circuit holds the switching circuit in a period in the normal operation mode to the ON state, the by the load control circuit to intermittently turned on and off the switching circuit switched period to the low power consumption mode An operation control means for intermittently energizing the resistance voltage dividing circuit ,
The backup control circuit performs control to return the load control circuit to a normal operation mode when a detection voltage of the resistance voltage dividing circuit becomes equal to or higher than the reference voltage during a period in which the switching circuit is in an ON state. A vehicle power supply device. A switching element for supplying a main power source for driving the load to be controlled to the load control circuit from the power line to the load control circuit;
A constant voltage power supply circuit for supplying a control power supply for the load control circuit from the power supply line to the load control circuit;
A voltage generation circuit for generating the reference voltage based on the output voltage of the constant voltage power supply circuit,
The backup control circuit turns off the switching element to switch the load control circuit when the load control circuit is switched to a low power consumption mode as the detection voltage of the resistance voltage dividing circuit becomes lower than the reference voltage. The circuit is switched to a state where only the control power is supplied to the circuit, and the load control circuit is instructed to interrupt the normal operation mode and store data necessary for returning to the normal operation mode in the storage means. The vehicle power supply device according to claim 1, wherein the vehicle power supply device is configured to give a backup operation command for performing the operation. The vehicle power supply device according to claim 2,
The switching circuit supplies an output voltage of the power supply line and an output voltage of the constant voltage power supply circuit to the resistance voltage dividing circuit and the voltage generation circuit when the switching circuit is in an on state, respectively. A power supply device for a vehicle, characterized in that the voltage supply to the generating circuit is simultaneously cut off.

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