JP2003263246A - Power supply circuit for electronic equipment - Google Patents

Abstract

(57) Abstract: A power supply for an electronic device that can control on / off of each DC-DC converter at an appropriate timing while preventing a rush current even when connecting a power supply having two or more types of different impedances. Provide a circuit. A power supply circuit for an electronic device according to the present invention includes an electronic circuit that requires a plurality of voltage levels to operate the electronic device body, and a plurality of DC-DC converters that supply power to the electronic circuit. A power supply terminal 16 for supplying power to each of the DC-DC converters 11 to 13;
An on / off control circuit 15 for on / off control of each of the DC-DC converters 11 to 13; two or more types of power sources can be connected; 18 is connected, and the on / off control circuit 15 controls each DC-DC converter 11 according to the detection result of the impedance detection means 18.
The on-time interval Δt at which .about.13 are sequentially turned on is changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply circuit for an electronic device that is driven by using power from a power supply having two or more different impedances.

[0002]

2. Description of the Related Art Conventionally, in portable electronic equipment such as a notebook computer, a battery is used as a power source when going out, and an AC adapter connected to a commercial power source is used as a power source indoors. It is being appreciated.

In a power supply circuit of an electronic device using two or more kinds of power supplies of this kind, as shown in FIG.
-DC converter 1, DC-DC converter 2, DC
-Connect the DC converter 3 and the electronic circuit 4 to the DC-D
The on / off control of the C converters 1 to 3 is performed by the on / off control circuit 5, and the DC-DC converters 1 to 3 are
Is used to generate a plurality of voltage levels necessary for the electronic circuit 4 from the voltages of the AC adapter and DC battery connected to the power supply terminal 6.

In this type of electronic device, when the power of the electronic device is turned on, the output terminals 7 of the DC-DC converters 1 to 3 are turned on.
When the capacitor connected to the side is charged, D
Inrush current is generated toward the C-DC converters 1 to 3,
There is a problem that a voltage drop occurs in the power supply terminal 6 of the electronic device, peripheral circuits including the electronic circuit 4 malfunction, and power consumption increases.

Therefore, conventionally, as shown in FIG.
On / off control signal F output from the off control circuit 5
By sequentially shifting the falling times t1, t2, and t3 of F1, F2, and F3, and shifting the timing at which each of the DC-DC converters 1 to 3 is turned on (that is, the output terminal 7
Of the voltages V1, V2, and V3 of (3) are temporally shifted) to slowly rise the rush current Δt.
Is prevented from flowing all at once from the power supply terminal 6 to the DC-DC converters 1 to 3, so that the voltage drop ΔV at the power supply terminal 6 is prevented as much as possible.

[0006]

However, each of the DC-DC converters 1 to 3 is controlled so that the voltage drop ΔV when the power source having a small output impedance, for example, the AC adapter is connected to the power source terminal 6 becomes a predetermined value or less. If the on-time is shifted, a power source with a large output impedance, for example, a power source with a low output impedance is connected to the power source terminal 6 as indicated by a broken line in the voltage drop ΔV ′ when a DC battery is connected to the power source terminal 6. There is an inconvenience that the voltage drop becomes larger than the voltage drop ΔV.

Therefore, it is conceivable to shift the timing at which each of the DC-DC converters 1 to 3 is turned on in correspondence with the power supply having a large output impedance, but each DC-DC converter 1 is made to correspond to the power supply having a large output impedance. If the timing to turn on 3 to 3 is determined, it takes time for the electronic device to stabilize after turning on the power of the electronic device, and it takes too long for the electronic device to become usable after the power is turned on. There is a problem. In particular, even when a power supply with a small output impedance is connected, if the timing at which the DC-DC converters 1 to 3 are turned on in correspondence with the power supply with a large output impedance, the power supply is actually used after being turned on. There is a problem that useless waiting time occurs before it can be done.

The present invention has been made in view of the above circumstances. Even when two or more types of power sources having different impedances are connected, each DC-DC converter is prevented at an appropriate timing while preventing an inrush current. It is an object of the present invention to provide a power supply circuit for an electronic device that can be on / off controlled.

[0009]

According to a first aspect of the present invention, there is provided a power supply circuit for an electronic device, wherein the electronic device requires a plurality of voltage levels to operate the electronic device main body, and power is supplied to the electronic circuit. Multiple DC-DC converters and each DC
-A power supply terminal for supplying power to the DC converter and each DC
In an electronic device that includes an on / off control circuit for performing on / off control of a DC converter and is capable of connecting two or more types of power sources, impedance detection means for detecting impedance of the power source is connected to the power source terminal. ,
The on / off control circuit is characterized by changing an on-time interval in which each DC-DC converter is sequentially turned on according to a detection result of the impedance detecting means.

According to another aspect of the present invention, there is provided a power supply circuit for an electronic device,
One of the two or more types of power supplies is an AC adapter, the other is a DC battery, and the AC adapter is connected to the power supply terminal at an ON time interval when the DC battery is connected to the power supply terminal. It is characterized in that it is made larger than the on-time interval when it is turned on.

According to another aspect of the present invention, there is provided a power supply circuit for an electronic device,
Of the two types of power supplies, the ON time interval when a battery with a large output impedance is connected to the power supply terminal is
It is characterized in that the battery having a small output impedance is made larger than the ON time interval when the battery is connected to the power supply terminal.

According to another aspect of the present invention, there is provided a power supply circuit for an electronic device,
One of the two types of power supplies is an alkaline manganese battery, the other is a NiCd / NiMH battery, and the on-time interval when the alkaline manganese battery is connected to the power supply terminal is the NiCd / NiMH battery. It is characterized by making it larger than the on-time interval when it is connected to the terminal.

According to another aspect of the present invention, there is provided a power supply circuit for an electronic device,
One of the two types of power sources is an alkaline manganese battery, the other is a lithium ion primary battery or a lithium ion secondary battery, and the on-time interval when the alkaline manganese battery is connected to the power supply terminal is It is characterized in that the ON time interval when the ion primary battery or the lithium ion secondary battery is connected to the power supply terminal is made larger.

According to a sixth aspect of the present invention, there is provided a power supply circuit for an electronic device,
One of the two types of power supplies is a near-empty battery with almost no remaining battery power, and the other is a nearly full battery with sufficient remaining battery power, and the near-empty battery is connected to the power supply terminal. It is characterized in that the on-time interval when the battery is turned on is made larger than the on-time interval when the battery, which is almost full, is connected.

A power supply circuit for an electronic apparatus according to a seventh aspect is
One of the two types of power sources is a battery whose temperature is lower than the temperature of the other battery, and the on-time interval when the low temperature battery is connected to the power supply terminal is the high temperature battery is connected to the power supply terminal. It is characterized in that it is made larger than the on-time interval when it is turned on.

According to the invention described in claims 1 to 7, each DC-DC converter is turned on / off at an appropriate timing while preventing an inrush current even when connecting two or more kinds of power sources having different impedances. Can be controlled.

That is, when a power source with high impedance is connected to the power supply terminal, the on-time interval of each DC-DC converter is increased, so that it is possible to prevent the rush current from flowing all at once to the power supply terminal. Therefore, it is possible to avoid the problems that the power supply does not turn on due to a large voltage drop, the electronic device malfunctions, and the power consumption increases, and the power supply is turned on when a low impedance power supply is connected to the power supply terminal. It is possible to avoid the problem that a wasteful waiting time occurs before the actual use. Further, it is possible to avoid shortening the battery life as much as possible when a battery with high impedance is connected.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 shows a power supply circuit for an electronic device according to the present invention. In FIG. 3, 11 to 13 are DC
-DC converter, 14 electronic circuits, 15 each DC-D
An on / off control circuit for turning on / off the C converters 11 to 13, 16 is a power supply terminal, and 17 is an output terminal.

Impedance detecting means 18 is connected to the power supply terminal 16. The impedance detecting means 18 has a function of detecting the impedance of the power supply 19 connected to the power supply terminal 16. The detection output of the impedance detecting means is input to the on / off control circuit 15. The on / off control circuit 15 functions as a timing changing unit that changes the on / off timings of the DC-DC converters 11 to 13 according to the detection result of the impedance detecting unit 18, and the DC-DC converters 11 to 13. It has a function as an on / off means for turning on / off. The on / off control circuit 15 is, for example,
It consists of a microcomputer, and the microcomputer is provided with a software timer, for example,
When a battery with high impedance is connected as the power source 19, as shown in FIG. 4, the DC-DC converter 1
ON / OFF control signal F1 for turning on 1 is turned off at time t1 ′ and then turned on / off control signal F2 for turning on DC-DC converter 12 at time t2 ′ and turned on / off control signal for turning on DC-DC converter 12 F2 is made to fall at time t2 ', and then the on / off control signal F2 for turning on the DC-DC converter 12 is made to fall at time t3'. As a result, each DC-DC converter 12 is sequentially turned on at each ON time interval Δt. That is, the voltage V of the output terminal 17
1, V2, and V3 are temporally shifted and gradually rise.

On the other hand, the power source 19 having a lower impedance than the DC battery, for example, the power source 19 is, for example, A
When the C adapter is connected to the power supply terminal 16, the on / off control unit 15 causes the on / off control signal F1 to fall at time t1 ″, as shown in FIG.
Time t after the time interval Δt ′ shorter than the on-time interval Δt
2 ″, the on / off control signal F2 is made to fall, and this on / off control signal o is made to fall at time t2 ″, and then a time interval Δt ′ shorter than the on time interval Δt.
At a later time t3 ″, the on / off control signal F3 is caused to fall. As a result, each DC-DC converter 12
Are sequentially turned on every time interval Δt ′ shorter than the on time interval Δt.

Therefore, when a power source with a high impedance is connected to the power supply terminal 16, the on-time interval Δt of each DC-DC converter 11 to 13 is an on-time interval when a power source with a low impedance is connected to the power supply terminal 16. As compared with Δt ′, as shown in FIG. 4, the inrush current ΔI to the power supply terminal 16 sequentially flows at every ON time interval Δt, and the voltage drop ΔV caused by the inrush current ΔI flowing at one time. Can be prevented from increasing.

On the other hand, when a power source with low impedance is connected to the power supply terminal 16, the ON time interval Δt 'of each DC-DC converter 11 to 13 is turned on when a power source with high impedance is connected to the power supply terminal 16. As shown in FIG. 5, the inrush current ΔI is smaller than the ON time interval Δt (2Δt ′).
It flows concentratedly within <Δt) at a time, but even if the inrush current ΔI flows at a time, the voltage drop ΔV is still at the power supply terminal 1
It is small because the impedance of the power supply connected to 6 is small. As a result, when a power source with a small impedance is connected, it is possible to prevent a useless waiting time from turning on the power source to actually being used.

Although the embodiment of the invention has been described above, the invention is not limited to this, but includes the following. (1) The two types of power sources are both DC batteries, and the ON time interval Δt when a DC battery with high impedance is connected to the power supply terminal is the ON time interval Δt ′ when a DC battery with low impedance is connected. Can be larger than. (2) One of the two types of power sources is an alkaline manganese battery, the other is a NiCd / NiMH battery, and the on-time interval Δt when the alkaline manganese battery is connected to the power supply terminal is calculated by the NiCd / NiMH battery. It can also be made larger than the on-time interval Δt ′ when connected to the power supply terminal. (3) One of the two types of power sources is an alkaline manganese battery, the other is a lithium ion primary battery or a lithium ion secondary battery, and the on-time interval Δt when the alkaline manganese battery is connected to the power supply terminal is It is also possible to make it larger than the on-time interval Δt ′ when the lithium ion primary battery or the lithium ion secondary battery is connected to the power supply terminal. (4) One of the two types of power supplies is a near-empty battery with almost no remaining battery, the other is a full battery with sufficient remaining battery, and the near-empty battery is connected to the power supply terminal. The on-time interval Δt when the battery is turned on can be made larger than the on-time interval Δt ′ when the battery, which is nearly full, is connected to the power supply terminal.

In this case, the ON time interval may be changed by using the battery remaining amount detecting circuit as the impedance detecting means. (5) One of the two types of power supply is a battery whose temperature is lower than the temperature of the other battery, and the high temperature battery is connected to the power supply terminal as the on-time interval when the low temperature battery is connected to the power supply terminal. It is also possible to make it larger than the on-time interval Δt when it is turned on.

In this case, a temperature sensor as impedance detecting means may be provided in the electronic device, and the on-time interval may be changed when the temperature of the temperature detecting sensor is below a predetermined temperature.

[0026]

According to the inventions of claims 1 to 7, each D is detected according to the detection result of the impedance detecting means for detecting the impedance of the power source connected to the power source terminal.
Since it is decided to change the on-time interval in which the C-DC converter is sequentially turned on, each DC-DC converter is prevented at an appropriate timing while preventing an inrush current even when connecting power sources having two or more types of different impedances. Can be controlled on and off.

That is, when a power source having a high impedance is connected to the power source terminal, the on-time interval of each DC-DC converter is increased, so that the voltage drop increases and the power source does not turn on, and the electronic device malfunctions. The problem of increased power consumption can be avoided, and when a power supply with low impedance is connected to the power supply terminal, the on-time interval of each DC-DC converter is made small, so after turning on the power supply, the actual It is possible to avoid the problem that useless waiting time occurs before it can be used.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a power supply circuit of a conventional electronic device.

FIG. 2 is a timing chart for explaining the relationship between inrush current and voltage drop.

FIG. 3 is a block diagram showing an example of a power supply circuit of an electronic device of the present invention.

FIG. 4 is a timing chart for explaining a relationship between an inrush current and a voltage drop when a power source with high impedance is connected to a power source terminal.

FIG. 5 is a timing chart for explaining a relationship between an inrush current and a voltage drop when a power source having a low impedance is connected to a power source terminal.

[Explanation of symbols]

11-13 DC-DC converter 143 Electronic circuit 15 ON / OFF control section 16 power terminals 18 Impedance detection means 19 power supply

Claims (7)

[Claims] 1. An electronic circuit that requires a plurality of voltage levels to operate an electronic device body, a plurality of DC-DC converters that supply electric power to the electronic circuit, and each DC-
A power supply terminal for supplying power to the DC converter and each DC-
An electronic device comprising an on / off control circuit for performing on / off control of a DC converter and capable of connecting two or more types of power sources, wherein an impedance detection means for detecting impedance of the power source is connected to the power source terminal, The on / off control circuit determines each D according to the detection result of the impedance detection means.
A power supply circuit for an electronic device, wherein an on-time interval in which a C-DC converter is sequentially turned on is changed. 2. One of the two or more types of power supplies is A
C adapter, the other is a DC battery, the ON time interval when the DC battery is connected to the power supply terminal,
The power supply circuit for an electronic device according to claim 1, wherein the power supply circuit is made larger than an ON time interval when the AC adapter is connected to the power supply terminal. 3. An on-time interval when a battery having a large output impedance is connected to the power supply terminal among the two types of power supplies, and an on-time interval when a battery having a small output impedance is connected to the power supply terminal. The power supply circuit for an electronic device according to claim 1, wherein the power supply circuit is larger than the above. 4. One of the two types of power sources is an alkaline manganese battery, the other is a NiCd / NiMH battery, and the ON time interval when the alkaline manganese battery is connected to the power source terminal is NiCd / The power supply circuit for an electronic device according to claim 1, wherein the NiMH battery has a larger ON time interval when connected to the power supply terminal. 5. One of the two types of power sources is an alkaline manganese battery, the other is a lithium ion primary battery or a lithium ion secondary battery, and is turned on when the alkaline manganese battery is connected to the power source terminal. The power supply circuit of the electronic device according to claim 1, wherein the time interval is set to be larger than an on-time interval when a lithium ion primary battery or a lithium ion secondary battery is connected to the power supply terminal. 6. One of the two types of power sources is a near-empty battery with almost no remaining battery power, and the other is a nearly full battery with a sufficient remaining battery power. 2. The power supply circuit for an electronic device according to claim 1, wherein an on-time interval when connected to the power supply terminal is set to be larger than an on-time interval when a nearly full battery is connected. 7. One of the two types of power supplies is a battery having a temperature lower than the temperature of the other battery, and the on-time interval when the battery having a low temperature is connected to the power supply terminal is The power supply circuit for an electronic device according to claim 1, wherein the power supply circuit is made larger than an on-time interval when connected to the power supply terminal.