JPH0591660A - Power supply switching circuit - Google Patents

Abstract

(57) [Abstract] [Object] The present invention selects a power source having the highest efficiency according to the power consumption from among a plurality of power sources and uses the power source to increase power efficiency, and the output voltage decreases due to overload, resulting in system down. It is an object of the present invention to provide a power supply switching circuit that does not have such a problem. A circuit according to the present invention is a power supply switching circuit located between a main power supply and a load, the power detection unit 1 being connected to the main power supply and detecting the power consumption of the main power supply; and the power detection unit 1.
A power source unit 2 having a plurality of N sub-power sources connected to each other and a power source switch for connecting each of the sub-power sources to the load;
The power source switching circuit includes a power source switching control unit 3 that controls switching of the power source switching switch in response to the output signal of the power detection unit 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply switching circuit for selecting one of a plurality of power supplies having the highest efficiency in accordance with power consumption and switching to the power supply, and more particularly to a portable personal computer such as a notebook computer. The present invention relates to a power supply switching circuit used for the purpose of extending the battery life in electronic circuit devices such as.

[0002]

2. Description of the Related Art Conventionally, in a power supply circuit used for a notebook computer or the like, a power supply device for a DC / DC converter 21 and a series regulator 22 is provided as shown in FIG. 7, and the power consumption is large according to the power consumption. DC /
The DC converter 21 is used, and when the power consumption is small, the power source is switched so as to use the series regulator 22 to increase the power efficiency and to extend the life of the battery as the power source as long as possible.

Usually, the DC / DC converter has a high efficiency (about 80%) when the power consumption is large (50-100%) and a low efficiency (about 15-%) when the power consumption is small (10-20%). 20%). On the other hand, the series regulator has low efficiency when the power consumption is large, and high efficiency (about 50-60%) when the power consumption is small. Because the DC / DC converter requires the power consumed by its constituent circuit to be uniform regardless of the magnitude of the load current, the power consumption of the series regulator is output from the input of the series regulator. This is because the voltage drop to the Joule heat is consumed by the Joule heat, and when the load current is small, the Joule heat, that is, the power consumption in the series regulator is small.

However, in the actual use of a notebook computer, the load current is 1.3 A when the power consumption is large, and the load current is 10 mA when the power consumption is small. Therefore, in the notebook computer, when the power consumption is large, the DC / DC converter 21 is used, and when the power consumption is small, the series regulator 22 is used to improve the power efficiency to maximize the life of the battery as the power source. Can be lengthened.

The structure of a conventional power supply switching circuit will be described with reference to the block diagram of FIG. In FIG. 7, a power source unit 20 is a DC / DC converter 2 which is a power source.
1 and series regulator 22 and power supply selector switch (PWS) to turn on / off the output of series regulator 22
23 and. Reference numeral 50 denotes an operation mode switch (SW1), which is turned on to increase power consumption and turned off to decrease power consumption. Reference numeral 130 is a power supply switching control unit (P
WC) and turns on / off the DC / DC converter 21 and the series regulator 22 according to the operation mode changeover switch (SW1) 50, and further turns on / off all loads described later.

Next, the operation of the conventional power supply switching circuit will be described step by step with reference to the operation time chart of FIG. Step 1 ... When the operation mode switch (SW1) 50 is turned on, that is, when the power consumption increase signal is input to the power supply switching control unit (PWC) 130, the on / off signal (CONT1) of the series regulator 22 is immediately output. The signal is turned off, and the on / off signal (CO
NT2) turns on.

Step 2 ... As a result, the output of the series regulator 22 is turned off, and the DC / DC converter 21 is turned off.
The output of is turned on, the power consumption increases, and the state is changed to the state in which the power can be supplied. Step 3 ... Immediately after this, a full load on / off signal (CONT) that puts all the load circuits into a used state, that is, a state of large power consumption.
Turn on 3).

Step 4 ... Next, when the operation mode changeover switch (SW1) 50 is turned off, that is, the power consumption reduction signal is input to the power supply changeover control unit (PWC) 130, this time the full load on / off signal ( CONT3) is turned off and the load circuit is set to the low power consumption state, and it is predicted that the power consumption has decreased, and the on / off signal (CONT1) of the series regulator 22 is turned on and the DC / DC converter 21 is turned on / off. The signal (CONT2) turns off.

Step 5: As a result, the output of the series regulator 22 is turned on and the DC / DC converter 21 is turned on.
The output of is turned off and large power consumption cannot be supplied. From the above, for example, when power consumption is high in a notebook computer, that is, when a load such as LSI, IC, floppy disk, hard disk is connected as a load, a DC / DC converter is used, and when power consumption is low, the load is As RAM memory and RTC (clock) are connected as a power source, the power source is switched to use a series regulator, and the power source with higher efficiency is selected and used according to the power consumption to improve power efficiency. You can

However, after the normal load is switched from the large load to the small load, the DC / DC converter 21 is switched to the series regulator 22 when the power consumption is switched from the large power to the small load by the predictive control. As shown in the figure, when the power consumption is switched from the high power consumption to the low power consumption, when the power consumption is switched from the high power consumption to the low power consumption later than the power source is switched from the DC / DC converter 21 to the series regulator 22, the output voltage is lowered and the system is down. However, there is a problem that inconvenience occurs such that the contents of the memory are erased.

[0011]

Therefore, in order to solve such a problem, the present invention provides a means for detecting the magnitude of power consumption, and inserts a series regulator immediately before switching from high power consumption to low power consumption. It is an object of the present invention to provide a power supply switching circuit in which the output voltage does not drop and the system does not go down by confirming that the power consumption has decreased from high to low and turning off the DC / DC converter. ..

[0012]

A power supply switching circuit of the present invention for achieving the above object is a power supply switching circuit located between a main power supply and a load as shown in FIG. 1, and is connected to the main power supply. A power detection unit 1 for detecting power consumption of the power supply; a power supply unit 2 having a plurality of N sub power supplies connected to the power detection unit 1 and a power supply switch for connecting each of the sub power supplies to the load; And a power supply switching control unit 3 for switching and controlling the power supply changeover switch in response to the output signal of the power detection unit 1.

[0013]

According to the power supply device switching circuit of the present invention, when a load switching command is transmitted to the power supply switching control unit 3 by the operation mode switching switch (SW1), a load corresponding to the load switching command is connected to the output of the power supply unit 2. As a result, the load current changes, the power consumption is detected by the power detection unit 1, the detection signal is input to the power supply switching control unit 3, and the most efficient power supply unit responds to the detected power consumption. It is possible to provide an efficient power supply switching circuit in which the output voltage of the sub-power supply does not drop and the system does not go down by selecting the sub-power supply in 2 and switching and connecting it to the load.

[0014]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The configuration of an embodiment of the power supply switching circuit according to the present invention will be described with reference to the configuration diagram of FIG. In the figure, the same reference numerals as those used in the configuration diagram of the conventional power supply switching circuit are the same, and the description thereof will be omitted. Reference numeral 10 in the figure is a power detection unit, and when the current flowing to the load changes, the power detection unit 10
The voltage drop across the current sense resistor RS in the differential amplifier A
It is transmitted to MP1, amplified by several tens of times by the inverting amplifier AMP2, input to the A / D converter in the power supply switching control unit (PWC) 30, and the power consumption is detected. Reference numeral 30 denotes a power supply switching control unit (PWC), which is different from the conventional power supply switching control unit (PWC) 130 in that an A / D converter for converting an analog input from the current sensor unit 10 into a digital output is incorporated. And the operation of the switching control unit is different as described later.

Next, the output circuit diagram connected to the output of the power supply unit 2 shown in FIG. 3 will be described. The output circuit is composed of a load selector switch 45 and loads 40 (41, 42, 43) (L
D0, 1, 2, 3) and load changeover switch 45
Comprises output switch open / close drive circuits DR1,2,3 and respective output switches LSW1,2,3 for respective loads 41,42,43. On the other hand, the load 40 is a RAM memory or RTC (real time clock), the load 41 is an LSI or an IC, the load 42 is a floppy disk, and the load 43 is a hard disk.

First, referring to the operation time chart of FIG. 4 and the operation flow chart for shifting from the small power mode to the large power mode of FIG. 5, the operation of the power supply switching circuit according to the present invention will be described in the order of numbers 0 to 7 in FIG. It will be explained step by step.
In FIG. 5, reference numerals S0 to S6 indicate steps 0 to 6. A current constantly flows through the load 40 (LD0).

Step 0 ... First, the operation mode changeover switch (SW1) 50 is turned on in the small power mode. Step 1 ... The operation mode changeover switch (SW1) 50 is turned on, that is, the power consumption increase signal is transmitted to the power supply changeover control unit (P
When input to the WC) 30, the on / off signal (CONT2) of the DC / DC converter 21 is immediately turned on.

Step 2 ... As a result, the output of the DC / DC converter 21 is turned on, and even if the power consumption increases, the state where the power can be supplied is entered. Step 3 ... Next, the signal (CONT3) for instructing the increase / decrease of the load current is turned on after a lapse of a certain period of time after the output of the DC / DC converter 21 is turned on for several msec or more, or 10 msec in this embodiment.

Step 4 ... As a result, all the output switch opening / closing drive circuits DR1, 2, 3 in the load changeover switch 45 are turned on, and the output switch L in the load changeover switch 45 is turned on.
SW1, 2, 3 are all turned on and loads 41, 42, 43
A current flows through all of (LD1, 2, 3). When the load current increases, the current sense resistor R in the current sensor unit 10
The voltage drop across S is transmitted to the differential amplifier AMP1, amplified several tens of times by the inverting amplifier AMP2, and analog-inputted to the A / D converter in the power supply switching control unit (PWC) 30.

Step 5 ... This power supply switching control unit (PW
C) The current sensor information signal digitally converted by the A / D converter in 30 is the power supply switching control unit (PWC) 30.
It is input to the internal switching control unit to notify that the current consumption has increased. Step 6: The switching control unit turns off the signal (CONT1) for disconnecting the series regulator output according to this instruction.

Step 7: As a result, the output of the series regulator 22 is turned off. Next, referring to the operation time chart of FIG. 4 and the operation flow chart for shifting from the high power mode to the low power mode of FIG. 6, the operation of the power supply switching circuit according to the present invention is stepwise performed in the order of numbers 10 to 17 in FIG. Explained. Step 10 ... Next, operation mode switch (SW1)
50 turns off.

Step 11: When the operation mode changeover switch (SW1) 50 is turned off, that is, when the power consumption reduction signal is input to the power supply changeover control unit (PWC) 30, a signal (for immediately disconnecting the output of the series regulator 22) C
ONT1) is turned on. Step 12 ... Thereby, the output of the series regulator 22 is turned on. Step 13 ... Next, the signal (CONT3) for instructing the increase / decrease of the load current is turned off after a lapse of a fixed time and a few msec after the output of the series regulator 22 is turned on.

Step 14 ... As a result, all the output switch open / close drive circuits DR1, 2, 3 in the load changeover switch 45 are turned off and all the output switches (LSW1, 2, 3) are turned off, and the loads 41, 42, 43 (LD1, LD1, 2, 3)
The output current stops flowing in all of. Step 15 ... This reduces the load current. When the current decreases, the voltage drop across the current sense resistor RS in the power detection unit 10 is transmitted to the very small operation amplifier AMP1 and is amplified several tens of times by the inverting amplifier AMP2, and the A / D in the power supply switching control unit (PWC) 30. Analog input to the converter.

Step 16 ... This power supply switching control unit (PW
C) The current sense information signal digitally converted by the A / D converter in 30 is the power supply switching control unit (PWC) 30.
It is input to the internal switching control unit to notify that the current consumption has decreased. The switching control unit turns off the on / off signal (CONT2) of the DC / DC converter 21 according to this instruction.

Step 17 ... As a result, the output of the DC / DC converter 21 is turned off. By the above operation, the operation mode changeover switch (SW1) 50 is turned from ON to OFF, that is, the power consumption reduction signal is transmitted to the power supply changeover control unit (PWC).
When input to 30, the series regulator 22 immediately
Is turned on, and the information signal of the power detection unit 10 is input to the switching control unit in the power supply switching control unit (PWC) 30 to notify that the current consumption has sufficiently decreased, and as a result, DC /
Since the output of the DC converter 21 is turned off, it is possible to provide a power supply switching circuit in which the output voltage does not drop and the system does not go down without applying a heavy load only to the series regulator 22.

In this embodiment, the power detector 10 uses a circuit for detecting power consumption based on a change in current. However, power consumption may be detected based on a change in voltage. Further, the power detection unit 10, which is a circuit for detecting power consumption, can also be used for the purpose of displaying the life of the battery (indicating how many minutes the battery life is remaining).

As described above, according to the embodiment of the present invention, a means for detecting the magnitude of power consumption is added to the power supply switching circuit according to the prior art, and immediately before switching from high power consumption to low power consumption, With a series regulator,
Make sure that the power consumption has changed from high to low
By turning off the / DC converter, it is possible to provide a power supply switching circuit in which the output voltage does not drop and the system does not go down.

[0028]

According to the present invention, in a high-reliability computer such as a non-stop type computer in which system down is not allowed, two power supplies are provided and only one power supply is constantly used, while the other power supply is on standby. As soon as the power supply becomes abnormal, the power supply is switched and used for redundant operation (redundant operation system), but the power supply abnormal signal is caught as the current detection abnormal signal of the current sensor and the power supply in use occurs. It is conceivable to enable redundant operation by switching to the standby power supply when doing so.

Further, according to the present invention, since the most efficient power source is selected and used depending on the power consumption, the battery used as a power source for a notebook computer or the like can be extended in life. There is.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of a power supply switching circuit of the present invention.

FIG. 2 is a configuration diagram of a power supply switching circuit according to an embodiment of the present invention.

FIG. 3 is an output circuit diagram of the power supply switching circuit according to the embodiment of the present invention.

FIG. 4 is a time chart showing the operation of the power supply switching circuit according to the embodiment of the present invention.

FIG. 5 is an operation flowchart of the power supply switching circuit of the embodiment of the present invention for shifting from the low power mode to the high power mode.

FIG. 6 is an operation flowchart of the power supply switching circuit of the embodiment of the present invention shifting from the high power mode to the low power mode.

FIG. 7 is a configuration diagram of a conventional power supply switching circuit.

FIG. 8 is a time chart showing the operation of the conventional power supply switching circuit shown in FIG.

[Explanation of Codes] 1, 10 ... Power detection unit 2, 20 ... Power supply unit 3, 30, 130 ... Power supply switching control unit 21 ... DC / DC converter 22 ... Series regulator 40, 41, 42, 43 ... Load 45 ... Load Changeover switch 50 ... Operation mode changeover switch

Claims (3)

[Claims] 1. A power supply switching circuit in the middle of a main power supply and a load, comprising a power detection unit (1) connected to the main power supply for detecting power consumption of the main power supply, and the power detection unit (1). A power supply unit (2) having a plurality of N sub power supplies connected thereto and a power supply changeover switch connecting each of the sub power supplies to the load, and the power supply unit in response to an output signal of the power detection unit (1). A power supply switching circuit comprising a power supply switching control section (3) for switching control of the changeover switch. 2. The power source switching control unit (3) switches and connects the most efficient sub power source in the power source unit (2) to the load in accordance with the power consumption of the main power source. Power supply switching circuit. 3. The power supply switching control unit (3) switches and connects another sub power supply in the power supply unit (2) to the load when the sub power supply connected to the load is abnormal. Power supply switching circuit.