JP3711893B2 - Power circuit equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power supply circuit device that generates a stabilization voltage based on a power supply voltage and is formed based on a design standard having a breakdown voltage lower than the power supply voltage.
[0002]
[Prior art]
For example, when a power supply circuit that generates a power supply Vcc to be supplied to an electrical component such as an ECU (Electronic Control Unit) from a battery power supply of a vehicle is configured as an IC, a bipolar process is conventionally considered in consideration of a withstand voltage against the battery power supply voltage Vbatt It was common to form. However, since the microcomputer forming the center of the ECU is often formed by a CMOS process, there is an advantage in the manufacturing process if the power supply circuit can be formed by the same process.
[0003]
Therefore, an attempt has been made to form the power supply circuit device 1 as a CMOS process IC as shown in FIG. A power supply Vbatt of the battery 2 is applied to the power supply input terminal 1a of the power supply circuit device 1 via a current limiting resistor (resistance value r1) 3 so that an operating voltage Vclp is supplied. The power supply circuit device 1 includes a reference voltage generation circuit unit 4, a clamp circuit unit 5, and a regulator circuit unit 6. The reference voltage generation circuit unit 4 is, for example, a bandgap reference, receives the operation voltage Vclp, generates a reference voltage Vref (about 1.24 V), and supplies it to the clamp circuit unit 5 and the regulator circuit unit 6. Yes.
[0004]
In the clamp circuit unit 5, an operational amplifier 7 and an N-channel MOSFET 8 are connected between the power source Vclp and the ground, and a series circuit of voltage dividing resistors 9 and 10 is connected. A reference voltage Vref is applied to the inverting input terminal of the operational amplifier 7, and the non-inverting input terminal is connected to a common connection point of the voltage dividing resistors 9 and 10 (resistance values r2 and r3). The output terminal of the operational amplifier 7 is connected to the gate of the FET 8.
[0005]
In the regulator circuit unit 6, the operational amplifier 11 is operated by the power source Vclp together with the operational amplifier 7, and a reference voltage Vref is applied to a non-inverting input terminal. A series circuit of voltage dividing resistors 12 and 13 (resistance values r4 and r5) is connected between the stabilization voltage Vcc reference terminal 1b and the ground, and the common connection point between them is the inverting input terminal of the operational amplifier 11. It is connected to the. The output terminal of the operational amplifier 11 is connected to the base of the NPN transistor 14 disposed outside via the terminal 1 c of the power supply circuit device 1.
[0006]
The emitter of the transistor 14 is connected to the ground, and the collector is connected to the base of the PNP transistor 15. The emitter of the transistor 15 is connected to the battery 2, and the collector outputs a stabilized voltage Vcc (for example, 5V).
[0007]
The reference voltage generation circuit unit 4 generates a reference voltage Vref of 1.24V when the operating voltage Vclp reaches about 2V in the process of increasing the voltage Vbatt. The rated value of the reference voltage Vref is the clamp circuit unit. 5 or the regulator circuit unit 6 only needs to be determined before it steadily operates.
[0008]
In the power supply circuit device 1 configured as described above, the operational amplifier 11 of the regulator circuit unit 6 outputs a current supplied to the base of the external transistor 14 based on the difference between the divided potential of the power supply Vcc and the reference voltage Vref. To do. When the transistor 14 is turned on, the transistor 15 is also turned on, so that a current is supplied from the battery 2 and the potential of the power source Vcc is adjusted to be constant (Vcc = (r4 + r5) × Vref / r5). That is, since the power supply voltage Vbatt of the battery 2 fluctuates between 6V and 18V, for example, it is stabilized to generate a constant voltage Vcc, and the stabilized voltage Vcc is supplied as a power source to each unit (not shown).
[0009]
The operational amplifier 7 of the clamp circuit unit 5 controls the voltage applied to the gate of the FET 8 based on the difference between the divided potential of the power source Vclp and the reference voltage Vref. That is, the power supply circuit device 1 is formed by a CMOS process whose breakdown voltage is set lower than the voltage Vbatt of the battery 2 (for example, 5.5 V). For this reason, the clamp circuit unit 5 prevents the voltage Vclp from exceeding its breakdown voltage (Vclp = (r2 + r3) × Vref / r3, for example, 5.2 V), and if the voltage Vbatt is equal to or higher than the voltage Vrs, the FET 8 Adjustments are made by bypassing the current. By disposing such a clamp circuit unit 5, the power supply circuit device 1 can be formed by a CMOS process.
[0010]
FIG. 5 shows the relationship between the power supply voltage Vbatt of the battery 2 and the voltages Vclp and Vcc. As the level of the voltage Vbatt is higher, the current i1 flowing into the clamp circuit unit 5 through the current limiting resistor 3 increases, and thus the voltage Vclp also increases. If the voltage Vclp is equal to or higher than the level at which the operational amplifier 11 can operate, current is supplied to the base of the transistor 14 and the voltage Vcc is output.
[0011]
[Problems to be solved by the invention]
Here, the voltage Vbatt when Vcc reaches (r4 + r5) × Vref / r5 is defined as the minimum starting voltage Vl, and the resistance of the current limiting resistor 3 when the voltage Vbatt of the battery 2 is in a steady state (for example, 12 V) FIG. 6 shows the relationship between the value r1, the consumption current of the battery 2, and the voltage Vl. That is, if the resistance value r1 is decreased, the current i1 increases, so that the voltage Vclp when the battery 2 is connected reaches a sufficient level. As a result, even when the voltage Vbatt of the battery 2 is at a low level, it is possible to supply a predetermined level of the stabilized voltage Vcc, and the minimum starting voltage Vl is lowered. However, on the other hand, even when the voltage Vbatt is low, the FET 8 that bypasses the current operates in order to suppress the increase in the voltage Vclp, resulting in an increase in current consumption. On the contrary, when the resistance value r1 is set large, the current i1 decreases, so that the minimum starting voltage Vl increases but the current consumption can be suppressed.
[0012]
In the in-vehicle power supply circuit device 1, the resistance value r <b> 1 is generally set to a large value in order to suppress the consumption of the battery 2. For this reason, the minimum starting voltage Vl in the device 1 is set high, and there is a problem that the stabilization voltage Vcc cannot be maintained at a predetermined level in a region where the voltage Vbatt of the battery 2 is low.
[0013]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power supply circuit device capable of generating a necessary level of stabilization voltage even when the power supply voltage is low without increasing current consumption. is there.
[0014]
[Means for Solving the Problems]
According to the power supply circuit device of the first aspect, the clamp circuit unit generates the operation voltage clamped to be less than the withstand voltage by stepping down the output voltage of the power supply through the resistor, and the regulator circuit unit includes: In order to stabilize the output voltage of the power supply, a voltage drop element arranged outside is controlled to generate a stabilized voltage. The comparator compares the stabilization voltage with the operation voltage, and when the former exceeds the latter by a predetermined level or more, the switching element in which the stabilization voltage and the operation voltage are respectively applied to the two output side terminals. Turn it on.
[0015]
That is, when the power supply is connected to the power supply circuit device, when the above condition is satisfied and the comparator turns on the switching element, current is supplied from the stabilization voltage side to the operation voltage side. It rises momentarily. Therefore, even when the resistance value of the resistor is set to be large in order to suppress power consumption, the operation of the regulator circuit unit can be started by promoting the increase of the operating voltage by the action of the comparator and the switching element. As a result, since the minimum starting voltage can be made lower than that of the conventional configuration, a stabilization voltage of a predetermined level can be generated even when the power supply voltage is at a low level.
[0016]
Since the power supply circuit device according to claim 2 is configured as a semiconductor integrated circuit device formed by a CMOS process, for example, when applied to a power supply circuit that supplies a stabilization voltage to an element such as the microcomputer described above. The two can be formed integrally on the same semiconductor substrate, and the whole can be miniaturized.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to a power supply circuit device mounted on a vehicle will be described with reference to FIGS. The same parts as those in FIG. 4 are denoted by the same reference numerals, and the description thereof is omitted. Only different parts will be described below.
[0018]
In FIG. 1 showing an electrical configuration, a power supply circuit device 21 of the present embodiment is configured by adding a comparator 22 and a P-channel MOSFET (switching element) 23 to the power supply circuit device 1. The non-inverting input terminal of the comparator 22 is connected to the non-inverting input terminal of the operational amplifier 7, and the inverting input terminal is connected to the inverting input terminal of the operational amplifier 11. The output terminal of the comparator 22 is connected to the gate of the FET 23. The source (output side terminal) of the FET 23 is connected to the power input terminal 21a, and the drain (output side terminal) is connected to the terminal 21b for referring to the stabilization voltage Vcc.
[0019]
The comparator 22 has an internal threshold value set so that the output signal level is switched from high to low when the potential of the inverting input terminal is higher by 0.1 V than the potential of the non-inverting input terminal. Other configurations are the same as those in FIG.
[0020]
Next, the operation of this embodiment will be described with reference to FIGS. FIG. 2 is a view corresponding to FIG. As in FIG. 5, the voltage Vclp rises according to the level of the voltage Vbatt, and when the operational amplifier 11 has reached a level at which it can operate, the voltage Vcc is also output. The rising lines of the voltage Vclp and the voltage Vcc, which have different slopes as the voltage Vbatt rises, intersect, but when the voltage Vcc exceeds the voltage Vclp by 0.1 V (Vcc ≧ Vclp + 0) .1) The output level of the comparator 22 is switched from high to low, and the FET 23 is turned on. Then, since the current i2 (see FIG. 1) is supplied from the drain side (voltage Vcc side) to the source side (voltage Vclp side) of the FET 23, the level of the voltage Vclp rises instantaneously. In FIG. 2, the level increase of the voltage Vclp is exaggerated, but in reality, it increases to the same level as the voltage Vcc.
[0021]
That is, the change locus of the voltage Vclp according to the level of the voltage Vbatt becomes nonlinear due to the action of the comparator 22 and the FET 23. Therefore, assuming that the voltage Vbatt rises transiently within a very short time when the battery 2 is first connected to the power supply circuit device 21, the voltage Vclp rises by changing nonlinearly. Thus, the minimum starting voltage Vl increases.
[0022]
If the voltage Vcc reaches (r4 + r5) × Vref / r5, the voltage Vcc is stabilized by the operation of the regulator circuit section 6 as in the prior art, and is controlled to maintain that level. Further, when the voltage Vclp reaches (r2 + r3) × Vref / r3, the clamp circuit unit 5 is controlled so as to maintain the level. In a steady state where the voltage Vcc is stabilized at a predetermined level, the FET 23 is not turned on.
[0023]
Therefore, as shown in FIG. 3, even when the resistance value r1 of the current limiting resistor 3 is set to be large as in the conventional case and the operation start voltage Vrs of the regulator circuit unit 6 is set in the same manner, the minimum starting voltage Vl is higher than that in the conventional configuration. Therefore, the stabilized voltage Vcc can be generated even when the level of the voltage Vbatt when the battery 2 is relatively exhausted is lower. Since the FET 23 is turned on only while the battery 2 is first connected to the power supply circuit device 21 and reaches the steady state, the current consumption of only about several tens of μA flowing through the comparator 22 is increased in the steady state.
[0024]
As described above, according to the present embodiment, the clamp circuit unit 5 of the power supply circuit device 21 generates the operation voltage Vclp clamped by stepping down the output voltage Vbatt of the battery 2 through the current limiting resistor 3. The regulator circuit unit 6 controls the transistors (voltage drop elements) 14 and 15 arranged outside in order to stabilize the voltage Vbatt, and generates the stabilized voltage Vcc. The comparator 22 compares the stabilization voltage Vcc with the operating voltage Vclp, and when the former exceeds the latter by 0.1 V or more, the FET 23 is turned on to increase the operating voltage Vclp.
[0025]
Therefore, even when the resistance value of the current limiting resistor 3 is set large in order to suppress power consumption, the operation of the regulator circuit unit 6 is started by promoting the increase of the operating voltage Vclp by the action of the comparator 22 and the FET 23. Is possible. As a result, since the minimum starting voltage Vl can be made lower than that in the conventional configuration, it is possible to generate the stabilization voltage Vcc at a predetermined level even when the voltage Vbatt of the battery 2 is at a low level.
[0026]
In addition, since the power supply circuit device 21 is configured as a semiconductor integrated circuit device, if the power supply circuit device 21 is applied to a power supply circuit that supplies a voltage Vcc to an element configured by a CMOS process, such as a microcomputer, both are formed on the same semiconductor substrate. Thus, it can be configured integrally, and the whole can be miniaturized.
[0027]
The present invention is not limited to the embodiments described above and illustrated in the drawings, and the following modifications or expansions are possible.
The predetermined level is not limited to 0.1 V, and may be set as appropriate according to individual settings.
The voltage drop element is not limited to a transistor, and an IGBT, a power MOSFET, or the like may be used.
The reference voltage generation circuit unit 4 is not limited to a configuration using a band gap reference, and a Zener diode or the like may be used.
The switching element is not limited to the P-channel MOSFET 23, and an N-channel MOSFET may be used with the connection of the input terminal of the comparator 22 reversed. The power supply circuit device may be configured as an independent IC. Alternatively, they may be formed integrally on the same semiconductor substrate as the microcomputer formed by the same CMOS process and supplied with the stabilized power supply Vcc as the operation power supply.
Further, the power supply circuit device is not limited to being configured as an IC by a CMOS process, but may be configured by a discrete element, and even if it is formed by a bipolar process, it is formed with a withstand voltage reference lower than the voltage of the battery 2. Any power supply circuit device can be applied.
Moreover, it is not restricted to what is applied to the electrical component etc. of a vehicle.
[Brief description of the drawings]
FIG. 1 is a diagram showing an electrical configuration according to an embodiment in which the present invention is applied to a power supply circuit device mounted on a vehicle. FIG. 2 shows a power supply voltage Vbatt, an operating voltage Vclp, and a stabilization voltage Vcc. FIG. 3 is a diagram showing the relationship between the resistance value r1 of the current limiting resistor, the battery consumption current, and the minimum starting voltage Vl when the voltage Vbatt is in a steady state. Fig. 1 equivalent diagram [Fig. 5] Fig. 2 equivalent diagram [Fig. 6] Fig. 3 equivalent diagram [Explanation of symbols]
2 is a battery (power source), 3 is a current limiting resistor (resistor), 5 is a clamp circuit unit, 6 is a regulator circuit unit, 14 and 15 are transistors (voltage drop elements), 21 is a power circuit device, 22 is a comparator, Reference numeral 23 denotes a P-channel MOSFET (switching element).

Claims (2)

In a power supply circuit device that generates a stabilized voltage by stabilizing a power supply voltage and is formed according to a design standard having a withstand voltage lower than the power supply voltage,
A clamp circuit unit that generates an operation voltage clamped to be less than the withstand voltage by stepping down the power supply voltage through a resistor;
A regulator circuit unit configured to generate the stabilization voltage by controlling driving of a voltage drop element arranged outside to stabilize the power supply voltage;
A switching element to which the stabilization voltage and the operating voltage are applied to two output-side terminals,
A power supply circuit device comprising: a comparator that compares the stabilization voltage with the operating voltage and controls the switching element to be turned on when the former exceeds the latter by a predetermined level or more. 2. The power supply circuit device according to claim 1, wherein the power supply circuit device is configured as a semiconductor integrated circuit device formed by a CMOS process.

Images