CN1185780C - DC-DC transfer circuit, power selection circuit and equipment - Google Patents

Abstract

The present invention relates to a DC-DC conversion circuit and the like for converting a DC voltage into a lower DC voltage, and improves conversion efficiency. Equipped with a power supply selection unit (110), which has a plurality of input terminals (IN1, IN2), and a plurality of DC power sources (Vin1, Vin2) are input from these input terminals. Select the DC power supply of the lowest voltage; the step-down regulator unit (10), having an output terminal (OUT), converts the voltage of the DC power supply selected in the power supply selection unit into a prescribed voltage lower than the voltage ( Vout) is output from the output terminal.

Description

DC-DC conversion circuit, power selection circuit and device

technical field

The present invention relates to a DC-DC conversion circuit equipped with a DC voltage to another DC voltage, a power source selection circuit for selecting one of a plurality of power sources, and an apparatus equipped with a DC-DC conversion circuit.

Background technique

Many portable electronic devices such as notebook computers are configured so that, in addition to operating on electric power obtained from commercial power, a battery can be installed and operated using the battery.

In such a constructed device, generally, a circuit for switching between power from a commercial power supply and power from a battery is incorporated for the operation of the device (for example, refer to Japanese Patent Laid-Open Publication No. 9-182288, Japanese Patent Laid-Open Publication No. 9-308102 bulletin). Among the known circuits is a circuit that preferentially uses power from a commercial power supply to the device when it is supplied, and switches to battery power when the power supply from the commercial power supply is detected to be stopped. In addition, there is known a power supply switching circuit configured to receive power from the highest voltage among a plurality of electric power sources, taking advantage of the fact that the electric power from a commercial power supply is generally higher than the battery voltage.

However, since the voltage of a battery generally decreases slowly as it is discharged, a DC-DC conversion circuit is always provided in the equipment to maintain the voltage of the electric power used inside.

FIG. 7 is a circuit diagram showing a first example of the linear regulator. A linear regulator is a type of DC-DC conversion circuit and is generally widely used.

This linear regulator unit 10 is mounted on one LSI, and is configured such that the electric power of the input voltage Vin from the input terminal IN thereof is converted in the linear regulator unit 10 to an output voltage Vout ( Vin>Vout), the power of the output voltage Vout is output from the output terminal OUT.

Between the input terminal IN and the output terminal OUT, an NPN transistor 11 for adjusting the output voltage is arranged, and a constant current source 12 is arranged between the input terminal IN and the base of the NPN transistor 11, and the current output from the constant current source 12 is In addition to flowing as the base current of the NPN transistor 11 , it also flows as the collector current of the other NPN transistor 13 . The emitter of this NPN transistor 13 is connected to the ground terminal GND, and the ground terminal GND is grounded. The voltage Vout of the output terminal OUT is input to the positive input terminal of the differential amplifier 16 in the form of voltage division by two resistors 14 and 15, and the reference voltage generated by the reference voltage source 17 is input to the negative input terminal of the differential amplifier 16. Voltage. The output terminal of the differential amplifier 16 is connected to the base of the NPN transistor 13 .

Here, if the voltage Vout of the output terminal OUT deviates to be higher than a certain reference output voltage set in advance, the output voltage of the differential amplifier 16 increases, and the collector current flowing through the NPN transistor 13 increases. The portion of the current flowing out of 12 used as the collector current of the NPN transistor 13 increases, and as a result, the base current of the NPN transistor 11 for output voltage adjustment decreases, and the voltage Vout of the output terminal OUT drops.

On the other hand, on the contrary, if the voltage Vout of the output terminal OUT deviates to a voltage lower than a predetermined reference output, the output voltage of the differential amplifier 16 decreases, and the collector current flowing through the NPN transistor 13 decreases. , this part of the current increases the current of the transistor 11, and the voltage Vout of the output terminal OUT increases.

Through such control, electric power of a constant output voltage Vout can be output from the output terminal.

FIG. 8 is a circuit diagram showing a second example of the linear regulator. Differences from the first example shown in FIG. 7 will be described.

In the linear regulator unit 10' shown in FIG. 8, instead of the NPN transistor 11 for output voltage adjustment in the linear regulator unit 10 shown in FIG. The voltage Vout of the output terminal OUT divided by the two resistors 14 and 15 is input to the negative input terminal of the differential amplifier 16 , and the reference voltage source 17 is connected to the positive input terminal of the differential amplifier 16 .

Here, if the voltage Vout of the output terminal OUT deviates to a voltage higher than the preset reference output voltage, the output voltage of the differential amplifier 16 drops, and the collector current flowing through the NPN transistor decreases because the current from the constant current source Since the current flowing out of the PNP transistor 18 is constant, the base current of the PNP transistor 18 decreases in the part where the collector current decreases, and the voltage Vout of the output terminal OUT decreases with the decrease of the base current of the PNP transistor 18 .

On the other hand, on the contrary, if the voltage Vout of the output terminal OUT deviates to a voltage lower than the preset reference output voltage, the output voltage of the differential amplifier 16 rises, and the collector current flowing through the NPN transistor increases. Since the current flowing from the constant current source is constant, the base current of the PNP transistor 18 in which the collector current increases increases, and the voltage Vout of the output terminal OUT increases with the increase in the base current of the PNP transistor 18 .

In the linear regulator unit 10' shown in FIG. 8, by such control, electric power of a constant voltage Vout can be output from the output terminal OUT.

FIG. 9 is a circuit diagram showing a third example of the linear regulator.

The difference from the second example shown in FIG. 8 is that a P-channel MOS transistor 19 is arranged instead of the PNP transistor 18 for adjusting the output voltage shown in FIG. 8 . Since the circuit operation is the same as that of the second example shown in FIG. 8, repeated description is omitted.

FIG. 10 is a circuit diagram showing an example of a switching regulator. The switching regulator is also a kind of DC-DC conversion circuit, which is generally widely used.

The power of the voltage Vin is input from the input terminal IN of the switching regulator, and the output voltage Vout is output from the second output terminal OUT2 of the first and second output terminals OUT1 and OUT2 (here, the step-down type is targeted, so Vin>Vout ) of electricity. An external coil 31 is connected between the two output terminals OUT1 and OUT2, and an external capacitor 32 is connected between the second output terminal OUT2 and the ground.

A portion of the switching regulator 20 excluding the external coil 31 and capacitor 32 is fabricated on one LSI.

A P-channel MOS transistor 21 is arranged between the input terminal IN and the first output terminal OUT1, and the output of the PWM comparator 26 is connected to the gate thereof. The output of the differential amplifier 24 and the output of the triangular wave oscillator 27 are input to the PWM comparator 26 . The role of the PWM comparator 26 will be described later.

On the positive input terminal of the differential amplifier 24, the voltage Vout of the second output terminal OUT2 is input in the form of voltage division by two resistors 22 and 23, and on the negative input terminal of the differential amplifier 24, the voltage Vout of the reference voltage source 25 is input. The reference voltage generated in . In addition, a diode is connected between the first output terminal OUT1 and the ground terminal GND, and the cathode of the diode is connected to the first output terminal OUT side, and the anode of the diode is connected to the ground terminal GND side. The ground terminal GND is grounded.

Here, the PWM comparator 26 compares the output voltage of the differential amplifier 24 with the triangular wave signal output from the triangular wave oscillator 27, and generates an 'H' level pulse signal when the output voltage of the differential amplifier 24 is lower than the triangular wave voltage. , when the output voltage of the differential amplifier 24 is higher than the triangular wave voltage, a pulse signal of 'L' level is generated, and the pulse signal is input to the gate of the MOS transistor 21, and the MOS transistor 21 is based on the 'H' of the pulse signal Level, 'L' level changes, respectively become cut-off, conduction. That is, the MOS transistor 21 switches the input voltage Vin at the same repetition frequency as that of the triangular wave.

The diode 28, the coil 31, and the capacitor 32 function to generate Vout from the input voltage Vin after smoothing the switching.

If the output voltage Vout rises slightly compared to the set voltage, the output voltage of the differential amplifier 24 decreases, and the pulse width of the pulse signal generated in the PWM comparator 26 (pulse width of 'L' low level) Narrows slightly, and the output voltage Vout decreases. Conversely, when the output voltage Vout decreases, the output voltage of the differential amplifier 24 increases, the pulse width of the pulse signal generated by the PWM comparator 26 (pulse width of 'L' level) increases, and the output voltage Vout increases. . In this switching regulator 20, it is controlled so that electric power of a certain voltage Vout is output.

Here, for example, in electronic equipment such as a personal computer, there are many circuit units that operate at a plurality of different DC voltages, and such equipment is equipped with a plurality of DC-DC converters that output power at various voltages. circuit. The DC-DC conversion circuit consumes a considerable amount of reactive power during the conversion of the DC voltage, which leads to an increase in power consumption, premature consumption of the battery, and an increase in the temperature of the equipment. For example, in the case of the DC-DC conversion circuit of the linear regulator type shown in FIGS. 7 to 9, in order to convert the input voltage of 16V to the output voltage of 3.3V, the conversion efficiency is 20%, and the remaining 80% is all Power loss. In particular, in a device that uses a plurality of different DC voltages internally and requires a plurality of DC-DC conversion circuits to generate the different DC voltages, there is a problem of how to improve the conversion efficiency in the DC-DC conversion circuit.

Contents of the invention

In view of the above problems, the present invention provides a DC-DC conversion circuit with high conversion efficiency, a power supply selection circuit for voltage conversion with high conversion efficiency using the existing DC-DC conversion circuit, and a built-in DC converter with high conversion efficiency. -The purpose of the equipment device of the DC conversion circuit.

In order to achieve the above object, the first DC-DC conversion circuit in the DC-DC conversion circuit of the present invention is characterized in that it includes: a power supply selection unit, which has a plurality of input terminals, and a plurality of DCs are respectively input from each of these input terminals. Power supply, among these DC power supplies, the DC power supply with the lowest voltage is selected on the condition that the voltage is above the specified voltage; a step-down regulator, which has an output terminal, converts the DC power supply voltage selected in the power supply selection unit into A predetermined voltage lower than this voltage is output from the output terminal.

As mentioned above, in the case of a DC-DC conversion circuit of the linear regulator type, the conversion efficiency for converting 16V to 3.3V is 20%, and in the case of a 5V power supply, the conversion efficiency is 3.3V using the 5V power supply. The conversion efficiency at V becomes 66%. In this way, the conversion efficiency can be greatly improved by obtaining the output voltage from an input voltage as close as possible to the output voltage. The improvement in conversion efficiency by using an input voltage as low as possible is the same not only in the linear regulator system but also in the switching regulator system.

The first DC-DC conversion circuit of the present invention utilizes this principle.

That is, the power supply selection unit selects the DC power supply with the lowest voltage among the plurality of input DC power supplies and sends it to the regulator. However, even if it is the lowest voltage, in order to prevent the unconnected power supply or the connected power supply from being detected as the lowest voltage at 0V, which has no function, the condition is that it is higher than the specified voltage. In the regulator unit, the voltage of the DC power source selected in this way is changed to a DC voltage lower than the voltage and output. This makes it possible to efficiently convert the voltage of the optimal power supply selected according to the power supply situation at that time.

In addition, the second DC-DC conversion circuit in the DC-DC conversion circuit of the present invention is characterized by comprising: a power supply selection unit having a first input terminal for inputting a prescribed first DC power supply, an input ratio of the first DC power supply The second input terminal of the second DC power supply whose voltage is still lower, when the voltage of the second DC power supply input from the second input terminal is greater than or equal to a predetermined voltage, selects the second DC power supply input from the second input terminal. power supply, and when the voltage of the second DC power supply input from the second input terminal is less than a specified voltage, select the first DC power supply input from the first input terminal; the step-down regulator unit is placed in the above-mentioned power supply selection unit The voltage of the selected DC power supply is converted to a predetermined voltage lower than the voltage and output from the output terminal.

When it is determined that the second DC power supply voltage input from the second input terminal is a low-voltage DC power supply compared with the first DC power supply input from the first input terminal, or when it is configured to be connected, the above-mentioned present invention is followed. Considering the first DC-DC conversion circuit, the power supply selection unit can be simplified as described above.

Here, the above-mentioned regulator unit may be composed of a linear regulator regardless of which of the first and second DC-DC conversion circuits of the present invention. In this case, it is preferable to form a regulator unit comprising a power supply selection unit and a linear regulator in a monolithic integrated circuit. Or, in the case where the transistor for adjusting the output voltage is mounted externally, it is preferable to form the part of the transistor for adjusting the output voltage installed externally in the adjustment device that excludes the power supply selection unit and the linear regulator. inside the integrated circuit.

In addition, regardless of which of the first and second DC-DC conversion circuits of the present invention, the above-mentioned regulator unit may be composed of a switching regulator. In this case, it is preferable to form the part except the voltage smoothing circuit part installed externally in the regulator unit constituted by the power supply selection unit and the switching regulator, in a monolithic integrated circuit.

By forming it in a monolithic integrated circuit, more stable operation, cost reduction, and space saving can be realized.

In addition, the first power supply selection circuit in the power supply selection circuit of the present invention to achieve the above object is characterized in that it includes: a plurality of input terminals for inputting a plurality of DC power supplies; a power supply selection unit connected to these input terminals Among the plurality of DC power sources, the DC power source with the lowest voltage is selected on the condition that the voltage is higher than a predetermined voltage; the output terminal outputs the DC power source selected in the power source selection unit.

In addition, the second power supply selection circuit in the power supply selection circuit of the present invention is characterized by including: first and second input terminals for inputting a predetermined first DC power supply and a first DC power supply lower than the voltage of the first DC power supply, respectively. The second DC power supply of two voltages; the power supply selection unit, when the voltage of the second DC power input from the second input terminal is greater than or equal to the specified voltage, selects the second DC power input from the second input terminal, and in When the voltage of the second DC power input from the second input terminal is lower than a predetermined voltage, the first DC power input from the first input terminal is selected; the output terminal outputs the DC power selected in the power selection unit.

The first and second power supply selection circuits of the present invention are respectively equivalent to the power supply selection units of the first and second DC-DC conversion circuits of the present invention, and in the latter stages of these first and second power supply selection circuits, corresponding According to the DC-DC conversion circuit of the regulator unit of the first and second DC-DC conversion circuits of the present invention, high-efficiency DC-DC conversion can be performed in the DC-DC conversion circuit.

In addition, the facility device of the present invention that achieves the above object is characterized in that the facility device that operates after receiving the supply of electric power includes:

a step-down first DC-DC converter, which converts the first DC voltage of the prescribed first DC power supply into a prescribed second DC voltage lower than the first DC voltage and outputs it;

a first operating circuit which operates by receiving the power supply of the second DC voltage obtained in the first DC-DC converter;

The second DC-DC converter has a step-down regulator unit, which receives the input DC voltage and converts it into a specified third DC voltage lower than the DC voltage and then outputs it; a power supply selection unit, which inputs the above-mentioned Both the first DC power supply and the output of the first DC-DC converter transmit the output of the first DC-DC converter to the above-mentioned a regulator unit, and when the output of the first DC-DC converter is less than a specified voltage, the first DC power is delivered to the regulator unit;

The second operation circuit operates by receiving the power supply of the third DC voltage obtained in the second DC-DC converter.

The equipment device of the present invention is equipped with two DC-DC converters, the first DC-DC converter and the second DC-DC converter, by using the second DC-DC converter that outputs a lower DC voltage as The configuration of the first or second DC-DC conversion circuit of the present invention can perform DC-DC conversion with high efficiency as a whole, reduce power consumption, and suppress temperature rise of equipment.

Here, the power supply system and the like are generally pre-wired inside the equipment. Therefore, the second DC-DC conversion circuit of the present invention can generally be used as the above-mentioned second DC-DC converter, but the first DC-DC conversion circuit of the present invention can also be used. DC-DC conversion circuit. At this time, the power supply selection part of the second DC-DC converter cuts off the first DC power supply when the output of the first DC-DC converter does not reach the specified voltage and the first DC power supply does not reach the specified voltage. The output of a DC-DC converter is delivered to both the pathway on the regulator unit and the pathway delivering the first DC power to the regulator unit.

FIG. 1 is a circuit diagram of Embodiment 1 of a DC-DC conversion circuit of the present invention including Embodiment 1 of a power supply selection circuit of the present invention.

2 is a circuit diagram of Embodiment 2 of the DC-DC conversion circuit of the present invention including Embodiment 2 of the power supply selection circuit of the present invention.

Fig. 3 is a circuit diagram of Embodiment 3 of the DC-DC conversion circuit of the present invention.

Fig. 4 is a circuit diagram of Embodiment 4 of the DC-DC conversion circuit of the present invention.

Fig. 5 is a circuit diagram of Embodiment 5 of the DC-DC conversion circuit of the present invention.

Fig. 6 is a block diagram showing an embodiment of the apparatus device of the present invention.

FIG. 7 is a circuit diagram of a first example of a linear regulator.

FIG. 8 is a circuit diagram of a second example of the linear regulator.

FIG. 9 is a circuit diagram of a third example of the linear regulator.

FIG. 10 is a circuit diagram of an example of a switching regulator.

Embodiments of the present invention will be described below.

FIG. 1 is a circuit diagram of Embodiment 1 of a DC-DC conversion circuit of the present invention including Embodiment 1 of a power supply selection circuit of the present invention.

The DC-DC conversion circuit 100 shown in FIG. 1 is composed of an input selection circuit 110 and a linear regulator unit 10 . Here, the entire DC-DC conversion circuit 100 is produced in one LSI chip 190 . The input selection circuit 110 is also an embodiment of the power supply selection circuit of the present invention.

This input selection circuit 110 is provided with two input terminals IN1 and IN2 respectively connected to DC power sources, and here, it is assumed that input voltages Vin1 and Vin2 are input from the respective input terminals IN1 and IN2.

Each of the input terminals IN1, IN2, and the node TML for transmitting and receiving signals from the input selection circuit 110 to the linear regulator unit 10 (when the input selection circuit 110 is configured as a circuit separated from the linear regulator unit 10 (for example, only When the input selection circuit 110 is mounted on one LSI), the node TML becomes the output terminal of the input selection circuit 110), and the diodes 111 and 112 with anodes connected to the input terminals IN1 and IN2, and the P-channel MOS transistors 113, 114. In addition, the input sides of the P-channel MOS transistors 113 and 114 are connected to their respective gates through resistors 115 and 116, respectively. Also, N-channel MOS transistors 117 and 118 are disposed between the gates of the P-channel MOS transistors 113 and 114 and the ground terminal GND, respectively. The ground terminal GND is grounded.

In addition, in this input selection circuit, first, second and third comparators 121, 122, 123 and one reference voltage source 124 are provided, and a diode is connected to the positive input terminal of the first comparator 121. The cathode of 111 is connected to the reference voltage source 124 on its negative input terminal. On the second comparator 122, the cathode of diode 112 is connected on the positive input terminal 5, and the cathode of diode 111 is connected on the negative input terminal. The reference voltage source 124 is connected to the positive input terminal of the comparator 123, and the cathode of the diode 112 is connected to the negative input terminal.

The outputs of the three comparators 121, 122, 123 are delivered to the N-channel MOS transistor 117 through the first logic circuit 133 composed of the AND gate 131 and the OR gate 132, and in addition, through the first logic circuit 133 composed of the OR gate 134 and the NAND gate 135. The second logic circuit 136 passes to the gate of another N-channel MOS transistor 118 .

Here, the first comparator 121 compares the voltage Vin1 of the first input terminal IN1 with the voltage of the reference voltage source 124 to determine whether the voltage Vin1 of the first input terminal IN1 is higher than the voltage of the reference voltage source 124 . In other words, it is determined whether or not a power supply is being connected to the first input terminal IN1.

Similarly, the third comparator 123 compares the voltage Vin2 of the second input terminal IN2 with the voltage of the reference voltage source 124 to determine whether the voltage Vin2 of the second input terminal IN2 is higher than the voltage of the reference voltage source 124 . It is also determined whether or not a power supply is being connected to the second input terminal IN2.

The second comparator 122 is different from the first comparator 121 and the third comparator 123 in that the respective voltages Vin1 and Vin2 of the two input terminals IN1 and IN2 are compared with each other.

When the voltage Vin1 of the input terminal IN1 is a voltage above the reference voltage, and Vin1<Vin2, a signal of 'H' level is output from the first logic circuit 133, the NMOS transistor 117 is turned on, and the gate of the PMOS transistor 113 When the potential is lowered to the ground side, the PMOS transistor 113 is turned on, and the voltage Vin1 of the first input terminal IN1 is transmitted to the linear regulator unit 10 through the node TML. At this time, the output of the second logic circuit 136 (the gate of the NMOS transistor 118) becomes 'L' level, the NMOS transistor 118 is turned off, the PMOS transistor 114 is also turned off, and the voltage of the second input terminal IN2 Vin2 cannot be delivered to the linear regulator unit 10 .

Here, as an example, assuming that Vin1=5.0V and Vin2=16.0V, when the linear regulator unit 10 outputs a voltage of 3.3V, in the input selection circuit 110, since Vin1=5.0V is selected, the linear regulator The efficiency of unit 10 becomes 66%.

In contrast, when Vin2<Vin1, the output of the first logic circuit 133 becomes 'L' level and the output of the second logic circuit 136 becomes 'H' on the condition that the voltage of Vin2 is equal to or higher than the reference voltage. level. As a result, NMOS transistor 117 and PMOS transistor 113 are turned off, NMOS transistor 118 and PMOS transistor 114 are turned on while preventing Vin1 from being transmitted to linear regulator unit 10 , and Vin2 is transmitted to linear regulator unit 10 . In this case, as an example, if it is assumed that Vin1=16.0V, Vin2=5.0V, and the linear regulator unit 10 outputs a voltage of 3.3V, since Vin2=5.0V is selected in the input selection circuit 110, the linear regulator unit The efficiency becomes 66%.

In addition, when Vin1 is above the reference voltage, but Vin2 is less than the reference voltage (typically, the input terminal IN2 is powered off), the first comparator 121 outputs a 'H' level signal, and the second comparator 122 outputs an 'L' level signal. Level signal, the third comparator 123 outputs 'H' level signal, as a result, the 'H' level signal is output from the first logic circuit 133, the 'L' level signal is output from the second logic circuit 136, and the NMOS transistor 117 is turned on, the PMOS transistor 113 is also turned on, while the NMOS transistor 118 is turned off, and the PMOS transistor 114 is also turned off. Therefore, in this case, the voltage Vin1 input from the first input terminal IN1 is delivered to the linear regulator unit 10 . When the linear regulator unit 10 outputs a voltage of 3.3V, the efficiency of the linear regulator unit 10 is 66% when Vin1=5.0V, and 20% when Vin1=16.0V.

On the other hand, on the contrary, when Vin1 is less than the reference voltage (typically, the input terminal IN1 is powered off), and Vin2 is above the reference voltage, the first comparator 121 outputs a 'L' level signal, and the second comparator The 'H' level signal is output from the comparator 122, the 'L' level signal is output from the third comparator 123, as a result, the 'L' level signal is output from the first logic circuit 133, and the 'L' level signal is output from the second logic circuit 136 'H' level signal. Therefore, the NMOS transistor 117 is turned off, and the PMOS transistor 113 is also turned off. On the other hand, the NMOS transistor 118 is turned on, and the PMOS transistor 114 is also turned on. Thus, the voltage Vin2 input from the second input terminal IN2 is delivered to the linear regulator unit 10 . In the case where the linear regulator unit 10 outputs a voltage of 3.3V, when Vin2=5.0V, the efficiency of the linear regulator unit 10 is 66%, and when Vin2=16.0V, the efficiency of the linear regulator unit 10 becomes 20%. .

The linear regulator unit 10 has the same configuration as the linear regulator shown in FIG. 7 , and generates a stable output voltage Vout lower than the respective voltages Vin1 and Vin2 of the two input terminals IN1 and IN2 based on the principle described with reference to FIG. 7 . (Vout<Vin1, Vin2), for example, Vout=3.3V is generated and output from the output terminal OUT.

In this way, in the case of the DC-DC changing circuit 100 shown in FIG. 1, it is because, among the two input voltages Vin1 and Vin2, the smaller voltage is transmitted to the linear regulator unit on the condition that it is equal to or higher than the reference voltage. 10 is used to generate the output voltage Vout, so DC-DC conversion with high conversion efficiency can be performed.

2 is a circuit diagram of Embodiment 2 of the DC-DC conversion circuit of the present invention including Embodiment 2 of the power supply selection circuit of the present invention.

The DC-DC conversion circuit 200 shown in FIG. 2 is equipped with an input selection circuit 210 simpler than the input selection circuit 110 of Embodiment 1 shown in FIG. 1 , and a linear regulator unit similar to that of Embodiment 1 shown in FIG. 1 10 constitute the same linear regulator unit 10 . Here, as in the first embodiment shown in FIG. 1 , the entire DC-DC conversion circuit 200 is produced in one LSI chip 290 .

The DC-DC conversion circuit 200 shown in FIG. 2 is a circuit in which the respective input voltages Vin1 and Vin2 input from the respective input terminals IN1 and IN2 are guaranteed to be in the state of Vin1>Vin2 in advance. Assuring that Vin1>Vin2 can be realized, for example, by changing the form of the connection terminal, or by pre-fixed wiring inside the equipment, or the like.

When the first input terminal IN1 among the two input terminals IN1 and IN2, and the node TML connecting the input selection circuit 210 and the linear regulator unit 10 (when the input selection circuit (the power supply selection in the present invention) One example of the circuit) When it is provided as a circuit separate from the linear regulator unit 10 (for example, only the input selection circuit 210 is produced on one LSI chip), the node TML becomes the output terminal of the input selection circuit 210), A diode 211 and a PMOS transistor 213 having an anode connected to the input terminal IN1 side are provided. The diode 211 side of the PMOS transistor 213 is connected to its gate through a resistor 215 . Also, an NMOS transistor 217 is arranged between the gate of the PMOS transistor 213 and the ground terminal GND. The ground terminal GND is grounded.

In addition, a diode 212 having an anode connected to the input terminal 2 side is disposed between the other input terminal IN2 and the node TML, and a cathode of the diode 212 is also connected to the negative input terminal of the comparator 221 . Also provided therein is a reference voltage source 224 connected to the positive input terminal of the comparator 221 . The output of the comparator 221 is connected to the gate of the NMOS transistor 217 .

Here, in the comparator 221 , the voltage Vin2 of the second input terminal IN2 is compared with the reference voltage obtained from the reference voltage source 224 . Thereby, it is determined whether or not the power supply is being connected to the second input terminal IN2.

When Vin2 is higher than the reference voltage, the output of the comparator 221 becomes 'L' level, and the NMOS transistor 217 is turned off, so the PMOS transistor 212 is also turned off, preventing the voltage Vin1 of the first input terminal IN1 from The voltage Vin2 of the second input terminal IN2 is transmitted to the linear regulator unit 10 . On the other hand, the voltage of the second input terminal IN2 is a voltage lower than the reference voltage (typically 0V), the output of the comparator 221 becomes 'H' level, and the NMOS transistor 217 becomes a conduction state, therefore, the PMOS transistor 213 also becomes a conduction state, and the voltage Vin1 of the first input terminal IN1 is transmitted to the linear regulator device unit 10.

In this way, the input selection circuit 210 of FIG. 2 is a circuit that is effective under the condition that Vin1>Vin2 is guaranteed. When Vin2 is valid, Vin2 is passed to the linear regulator unit 10. When Vin2 is invalid (0V, etc.), Vin1 is passed to Linear Regulator Unit 10.

The linear regulator unit 10 has the same configuration as the linear regulator shown in FIG. 1 , generates a stable output voltage Vout lower than each voltage Vin1, Vin2, and outputs it from an output terminal OUT.

In this way, in the case of the DC-DC conversion circuit 200 shown in FIG. 2, also among the two input voltages Vin1 and Vin2 (Vin1>Vin2), Vin2 is delivered to the linear regulator unit 10 for output when Vin2 is valid. Generation of the voltage Vout enables DC-DC conversion with high conversion efficiency.

Fig. 3 is a circuit diagram of Embodiment 3 of the DC-DC conversion circuit of the present invention. Differences from Embodiment 2 shown in FIG. 2 will be described.

The difference between the DC-DC conversion circuit 300 shown in FIG. 3 and the second embodiment shown in FIG. 2 is that the portion excluding the NPN transistor 11 constituting the output voltage adjustment unit of the linear regulator unit 10 is fabricated on one LSI chip. 390, the NPN transistor 11 is installed externally. Therefore, the LSI chip 390 needs to be provided with two output terminals OUT1 and OUT2 other than the output terminal OUT3 corresponding to the output terminal OUT of the second embodiment in FIG. 2 .

In terms of circuit operation, since it is the same as Embodiment 2 in FIG. 2 , repeated description is omitted, and the reason why the transistor 11 is mounted externally is because the DC-DC conversion circuit 300 can consume a considerable amount of power in the secondary (at the output terminal). The power is in a state of high current, and it is necessary to use a device that can withstand the level of this state as the transistor 11, so the transistor 11 is a large transistor, and in addition, for example, it needs to install a heat sink to dissipate heat, so it is not suitable for built-in Because of the transistors in the LSI chip.

In this way, in the DC-DC conversion circuit of the linear regulator type, the transistor for adjusting the output voltage is also mounted externally.

Fig. 4 is a circuit diagram of Embodiment 4 of the DC-DC conversion circuit of the present invention.

The DC-DC conversion circuit 400 shown in FIG. 4 consists of the input selection circuit 110 as the embodiment 1 of the power supply selection circuit of the present invention shown in FIG. 1 , and the same switching regulator unit as the switching regulator shown in FIG. 10 20 compositions. Since the circuit operations of the input selection circuit 110 and the switching regulator unit 20 have already been described, the description thereof will be omitted here. The DC-DC conversion circuit shown in FIG. 4 is fabricated on one LSI chip 490 except for the coil 31 and the capacitor 32 constituting the switching regulator unit 20 . This is because the coil 31 and the capacitor 32 are too large to be fabricated in an LSI chip.

In the input selection circuit 110, two input voltages Vin1 and Vin2 are input from two input terminals IN1 and IN2 (both of Vin1 and Vin2 may be low voltages), and among these two input voltages Vin1 and Vin2, the voltage above the reference voltage The voltage on the lower voltage side is input to the switching regulator unit 20 as a condition. Since the switching regulator unit 20 is a step-down type that generates an output voltage Vout lower than both Vin1 and Vin2, the conversion efficiency of the side that generates the output voltage Vout based on a lower input voltage (of course higher than the output voltage Vout) high. In this way, also in the embodiment shown in FIG. 4 , the output voltage Vout is generated by inputting the voltage of the lower voltage of Vin1 and Vin2 to realize efficient DC-DC conversion.

Fig. 5 is a circuit diagram of Embodiment 5 of the DC-DC conversion circuit of the present invention.

The DC-DC conversion circuit 500 shown in FIG. 5 consists of the input selection circuit 210 of Embodiment 2 of the power supply selection circuit of the present invention shown in FIG. 2 and the same switching regulator as the switching regulator unit 20 shown in FIG. 4 Unit 20 is composed. Since the circuit operations of the input selection circuit 210 and the switching regulator unit 20 have been described, the description is omitted here. The DC-DC conversion circuit shown in FIG. 5 is fabricated on one LSI chip 590, except for the coil 31 and the capacitor 32 constituting the switching regulator unit 20, as in the fourth embodiment shown in FIG.

In the input selection circuit 110, when the power supply is connected to both input terminals IN1 and IN2, it is necessary to ensure that Vin1>Vin2 is satisfied. Vin2 is delivered to the switching regulator unit 20, and Vin1 is delivered to the switching regulator unit 20 when Vin2 is a voltage below the reference voltage. Therefore, in the switching regulator unit 20, all high-efficiency DC-DC conversions are performed.

Fig. 6 is a block diagram showing an embodiment of the apparatus device of the present invention.

The device 600 is, for example, a notebook computer. The DC power of 16.0 V generated from a commercial power supply in an external AC outlet (not shown) and the DC power of 12 to 9 V from the built-in battery 611 are respectively transmitted through each Diode 612, 613 input. One of the DC power from the AC outlet is 16.0V, which is higher than the battery voltage (12-9V), so when DC power is input from the AC outlet, no power is output from the battery due to the action of the diode 613 . When the power input from the AC outlet is interrupted and the device operates, power is supplied from the battery 611 . The power from the AC outlet or the power from the battery 611 is input to the DC-DC converter 614 (an example of the first DC-DC converter in the present invention) and the regulator 615 (the second DC-DC converter in the present invention). - an example of a DC converter).

The DC-DC converter 614 generates 5.0V power based on the input power and supplies it to the first operation circuit 616 . The first operating circuit 616 is driven and operated by the power of 5.0 V generated by the DC-DC converter 614 . In the DC-DC converter 614, a control signal (on/off signal) for turning on/off the action of the DC-DC converter is input, and when the first action circuit 616 is not required to operate, in order to save power, the DC-DC The operation of inverter 614 itself also stops.

To the regulator 615, in addition to the power from the AC outlet or the battery 611, the power of 5.0 V generated by the DC-DC converter 614 is input, and the voltage of the two powers input to the regulator 615 is lower. Based on the power of one side, generate 3.3V power. The 3.3V power generated by the regulator 615 is supplied to the second operation circuit 617 , and the second operation circuit 617 operates with the 3.3V power supplied from the regulator 615 . The second operation circuit 617 is composed of a circuit that requires continuous operation without power interruption, and the like.

In the regulator 615, although one of the various embodiments of the DC-DC conversion circuit of the present invention described above can be used, because it is pre-wired for installation in the equipment, for example, typically, the circuit shown in FIG. 2 can be used. The DC-DC converter circuit diagram.

When the DC-DC converter 614 operates and 5.0V power from the DC-DC converter 614 is input to the regulator 615, the regulator 615 generates 3.3V power based on the 5.0V power. If DC- When the operation of the DC converter 614 stops, the regulator 615 generates 3.3V power based on the 12V to 9V power from the battery 611 when the 16.0V power from the AC outlet is not connected or when the AC outlet is not connected.

In this way, since the regulator 615 is configured to generate 3.3V power from the 5.0V power generated here when the DC-DC converter 614 operates, in the regulator 615, regardless of the DC-DC converter Power saving is realized compared to the case of using the power from the AC outlet or the battery regardless of the operation.

Furthermore, as the regulator 615, for example, a DC-DC conversion circuit shown in FIG. 1 may be used. In this case, the input and output of the DC-DC converter 614 can be connected to either of the two input terminals during wiring, the wiring operation becomes easy, and it is possible to thoroughly prevent the two wirings from being mistaken. wiring errors.

As described above, according to the present invention, high-efficiency DC-DC conversion can be performed.

Claims (10)

1. a DC-DC translation circuit is characterized in that, is equipped with: the power supply selected cell, and it imports a plurality of DC power supplys from a plurality of input terminals, is the DC power supply that condition is selected minimum voltage more than assigned voltage with voltage; The voltage-dropping type conditioner unit, it is the DC power source voltage of selecting in above-mentioned power supply selected cell, and the voltage that is transformed to the regulation also lower than this voltage is exported from lead-out terminal.

2. DC-DC translation circuit, it is characterized in that, be equipped with: the power supply selected cell, first input end with DC power supply of input regulation, import second input terminal of the 2nd DC power supply of the voltage also lower than a DC supply voltage, from the 2nd DC power source voltage of this second input terminal input during more than or equal to assigned voltage, selection is from the 2nd DC power supply of above-mentioned second input terminal input, and, selecting from a DC power supply of first input end input during less than assigned voltage from the 2nd DC power source voltage of this second input terminal input; The voltage-dropping type conditioner unit, the voltage that the DC power source voltage of selecting is transformed to the regulation also lower than this voltage in above-mentioned power supply selected cell is exported from lead-out terminal.

3. as claim 1 or 2 described DC-DC translation circuits, it is characterized in that: above-mentioned conditioner unit is made up of linear regulator.

4. DC-DC translation circuit as claimed in claim 3 is characterized in that: the above-mentioned conditioner unit that is made of above-mentioned power supply selected cell and linear regulator is formed in the monolithic integrated circuit.

5. DC-DC translation circuit as claimed in claim 3, it is characterized in that: remove with above-mentioned power supply selected cell, and the output voltage adjustment that is installed in the outside in the above-mentioned conditioner unit of linear regulator formation is formed in the monolithic integrated circuit with the other parts outside the transistor.

6. as claim 1 or 2 described DC-DC translation circuits, it is characterized in that: above-mentioned conditioner unit is made of switching regulaor.

7. DC-DC translation circuit as claimed in claim 6, it is characterized in that: remove with above-mentioned power supply selected cell, and the other parts outside the voltage smoothing circuit part that is installed in the outside in the above-mentioned conditioner unit of switching regulaor formation, be formed in the monolithic integrated circuit.

8. a power selection circuit is characterized in that being equipped with: a plurality of input terminals that are used for importing a plurality of DC power supplys; The power supply selected cell in a plurality of DC power supplys on being connected above-mentioned a plurality of input terminal, is the DC power supply that condition is selected minimum voltage more than assigned voltage with voltage; Lead-out terminal, the DC power supply that output is selected in above-mentioned power supply selected cell.

9. a power selection circuit is characterized in that being equipped with: first and second input terminal, the 2nd DC power supply of a DC power supply of input regulation respectively and second voltage also lower than a DC power source voltage; The power supply selected cell, from the 2nd DC power source voltage of this second input terminal input during more than or equal to assigned voltage, selection is from the 2nd DC power supply of above-mentioned second input terminal input, and, selecting from a DC power supply of first input end input during less than assigned voltage from the 2nd DC power source voltage of this second input terminal input; Lead-out terminal, the DC power supply that output is selected in above-mentioned power supply selected cell.

10. receive electric power and supply with the apparatus that moves, comprising:

The one DC-DC converter of voltage-dropping type, it is transformed to second dc voltage and the output of the regulation also lower than this first dc voltage to first dc voltage of a DC power supply of regulation;

First actuating circuit, the electric power that it is received in above-mentioned second dc voltage that obtains in the above-mentioned DC-DC converter is supplied with and is moved;

The 2nd DC-DC converter has the voltage-dropping type conditioner unit, and its is exported after receiving the dc voltage of input and it being transformed to the 3rd dc voltage of the regulation also lower than this dc voltage; The power supply selected cell, it imports the both sides of the output of an above-mentioned DC power supply and an above-mentioned DC-DC converter, in the output of a DC-DC converter during more than or equal to assigned voltage, the output of an above-mentioned DC-DC converter is delivered to above-mentioned conditioner unit, and during less than assigned voltage, an above-mentioned DC power supply is delivered to above-mentioned conditioner unit in the output of a DC-DC converter;

Second actuating circuit, the electric power that it is received in above-mentioned the 3rd dc voltage that obtains in above-mentioned the 2nd DC-DC converter is supplied with and is moved.

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