TW541778B - Power supply control device for electronic device equipped with multiple batteries - Google Patents

Abstract

A power supply control device for electronic device equipped with multiple batteries is disclosed, which is formed of transistors, a reference voltage circuit and a voltage comparison circuit. The transistors are connected to the battery and electronic devices respectively. The reference voltage circuit is connected to the electronic devices and voltage comparison circuit, so as to output the regulated load voltage, whose value is the load voltage minus the reference voltage to eliminate the output instability resulted from the offset voltage of the voltage comparison circuit. The voltage comparison circuit is connected to the reference voltage circuit, battery and transistors respectively. When the power supply voltage is larger than the regulated load voltage, it controls the transistors to turn on. Otherwise, it controls the transistor to turn off. The purpose is to make a diode close to the ideal one, and which is connected between the battery and the electronic devices in series.

Description

541778 V. Description of the Invention (1) [Field of the Invention] The present invention relates to a power supply control device, and more particularly to a power supply control device for an electronic device equipped with multiple batteries. [Background of the Invention] The development of science and technology is changing with each passing day. The advent of digital electronic products has brought more convenient life to people. And various portable devices, such as · mobile phones, laptops or personal digital assistants (Persona 1 Di g i t a 1

Assistance, PDA) ... and other rapid developments have greatly improved the convenience of human life and the efficiency of work.

The portable device can completely rely on its equipped battery as a power source without external power supply, providing the required power. The working time of a portable device without an external power source depends on the length of time that the battery can supply power continuously and steadily. At present, multiple battery groups are generally used to supply power at the same time or in turns to extend the working time of portable devices without external power supply. In this way, a power supply control device is needed to control the power supply status of each battery pack.

Please refer to Figure 1, which shows a circuit block diagram of a power supply control device used in a conventional portable device with dual batteries. The conventional method uses two diodes D1 and D2 to control the power supply status of the first battery 102 and the second battery 104. The diodes D1 and D2 are respectively coupled to the first battery 102 and the second battery 104, and are coupled to the node a together with the load 106. The load 106 may be any portable device that requires a battery to provide power. This is equivalent to connecting the first battery 102 and the second battery 104 in parallel. If the power supply voltage VB1 of the first battery 102 is greater than the power supply voltage VB2 of the second battery 104, the two poles

Page 4 541778 V. Description of the invention (2) The body D1 is turned on and the diode D2 is turned off. The power required for the load 106 is completely supplied by the first battery 102. Conversely, if the power supply voltage VB1 of the first battery 102 is smaller than the power supply voltage VB2 of the second battery 104, the diode D2 is turned on and the diode D1 is turned off, and the power required by the load 10 6 is completely supplied by the second battery 10 4 supply. In other words, the device determines the on and off of the diodes D1, D2 by comparing the magnitudes of the supply voltages VB1 and VB2 of the first battery 102 and the second battery 104, and then controls who needs to supply the load 106 electric power.

The above power supply control device has the disadvantage that when the diode is turned on, the two poles of the diode will have a voltage drop of about 0.35 to 0.7 volts. In other words, the supply voltage of the battery must be 0.3 to 5 · 7 volts higher than the load voltage for the diode to turn on. In this way, the power stored in the battery cannot be completely supplied to the load, thereby reducing the power supply capacity and time of the battery. Especially when the voltage of the battery is not high, the loss of the power supply capacity of the battery caused by the above method will become quite serious.

Please refer to Fig. 2, which shows a circuit block diagram of another power supply control device used in a conventional portable device with dual batteries. Different from the above method, this method uses two transistors M1 and M2 to replace the diodes D1 and D2 in the above method to control the power supply status of the first battery 202 and the second battery 204. Among them, the on and off of the transistors M 1 and M 2 are controlled by a micro control unit (MCU) 208. The micro control unit 208 can detect the presence of the first battery 202, the second battery 204, and the power supply voltage of the first battery 202 and the second battery 204 to output control signals to the transistors M1 and M2. Control the on and off of the transistors M1 and M2. When transistor M1 is on and transistor M2 is off, the power required by the load 2 0 6

Page 5 541778 V. Description of the invention (3) It is completely supplied by the first battery 202. Conversely, when the power transistor M2 is turned on and the power transistor M1 is turned off, the power required by the load 2 06 is completely supplied by the second battery 204. In other words, the power supply control device controls the on and off of the electric crystals M1 and M2 to control the power required by the first battery 202 or the second battery 204 to supply the load 206.

Although the above-mentioned power supply control device can solve the problem of voltage drop of the two poles when the diode is turned on, the power supply capacity and time of the battery can be improved. However, the disadvantage is that a micro-control unit is needed to detect and control the power supply of the battery, which increases the complexity of the control circuit and control method, and the manufacturing cost of the control circuit. In addition, it takes a reaction time for the micro-control unit to perform the measurement and control the battery operation. If the power supply battery is suddenly removed, or the power supply is suddenly unable to work normally for other reasons, it will take some time for the micro-control unit to detect this situation. During this time, although the transistor coupled to the other battery is turned off, the power supply voltage of the other battery will forcibly turn on the body diode of the transistor. Output power to the load until the transistor is turned on. When the diode is turned on, the two poles have a forward voltage with a size of about 0.7 volts. For the load, when the battery that is supplying power suddenly fails to supply power normally, the supply voltage of the input load will drop by about 0.7 volts in an instant. This instantaneous voltage drop of about 0.7 volts has a great impact on the working conditions of the load, especially the load with a low operating voltage. In addition, if the power supply voltage of the battery is not high at that time, the above method may cause the load to mistakenly believe that the battery power is insufficient, or even forcibly shut down, resulting in the loss of user data and inconvenience in use. Also, if a new battery is added as the negative

Page 6 541778 V. Description of the invention (4) If a new power source is loaded, it is necessary to use a software program to reset the operation of the microcontroller, which is difficult. [Objective and Summary of the Invention] In view of this, the object of the present invention is to provide a power supply control device for an electronic device equipped with multiple batteries, which can achieve the following objectives: 1. To reduce the pressure difference between the battery and the load. 2. Reduce circuit complexity and manufacturing costs. 3. You can increase or decrease the number of batteries configured.

4. The battery can be inserted and removed freely during the operation of the electronic device.

According to the purpose of the present invention, a power supply control device for an electronic device equipped with multiple batteries is provided to control the power supply status of the batteries. Each battery is coupled to the electronic device through an independent power supply control device. The battery has a power supply voltage and the load has a load voltage. Each power supply control device is composed of a transistor, a reference voltage circuit, and a voltage comparison circuit. Among them, the drain of the transistor is connected to the battery, and the source is connected to the electronic device. The reference voltage circuit is respectively coupled to the electronic device and the voltage comparison circuit, and the load voltage is adjusted according to the load voltage output, and the value is the difference between the load voltage and the reference voltage. The voltage comparison device has a first signal input terminal connected to a reference voltage circuit, a second signal input terminal coupled to a battery, and a signal output terminal coupled to a gate of a transistor, and outputs according to a supply voltage and an adjustment of a load voltage. Compare signals to control the on and off of the transistor. When the supply voltage is greater than the adjusted load voltage, the transistor is turned on and the battery is electrically coupled to the electronic device. When the supply voltage is less than the adjusted load voltage, the transistor is

Page 7 541778 V. Description of the invention (5) Closed, the battery and the electronic device are not electrically coupled. In order to make the above-mentioned objects, features, and advantages of the present invention more comprehensible, a preferred embodiment is exemplified below and described in detail with reference to the accompanying drawings. [Preferred Embodiment] The feature of the present invention is to use a hardware circuit to control and switch the power supply status of the battery to avoid the problem of voltage drop caused by the use of a diode. In addition, the present invention does not use a micro control unit to reduce the complexity of the circuit and the manufacturing cost. The power supply control device proposed by the present invention is equipped with an independent power supply control device for each battery to control the power supply condition of the battery. Instead of using a Micro Control Unit (MCU) to control the power supply status of all batteries, as is conventionally done. In this way, when the load needs to add a new battery as a new power source, it is only necessary to couple a new power supply control device with the new battery and the load, instead of using a software program to reset the operation of the micro control unit. More simple. Please refer to FIG. 3, which shows a circuit block diagram of a power supply control device for a portable device equipped with a dual battery according to the present invention. In the following, the power supply control device 300 (1) coupled to the first battery 300 is used as an example to describe the coupling relationship and working principle of the components of the power supply control device. The power supply control device 3 0 0 (1) is composed of a transistor M1, a reference voltage circuit 310 (1), and a voltage comparator 3 8 (1). In this embodiment, the transistor M 1 is a power metal-oxide semiconductor field-effect transistor of the P-channel (P-c hanne 1).

541778 V. Description of Invention (6)

Oxide Semiconductor Field Effect Transistor (Power MOSFET). The drain is coupled to the first battery 302, and the source is coupled to the load 306. The function of the transistor M 1 is equivalent to a switch 'for controlling the electrical connection between the load 3 06 and the first battery 3 02. The positive input terminal (+) of the voltage comparator 308 (1) is coupled to the reference voltage circuit 310 (1), the negative input terminal (-) is coupled to the battery 302, and the output terminal is connected to the gate of the transistor M1 ( gate), as shown in Figure 3. It should be noted that the load in FIG. 3 may be any portable device that requires a battery to provide power, such as a mobile phone, a notebook computer, or a Personal Digital Assistance (PDA). The positive terminal (0) of the reference voltage circuit 3 10 (1) is coupled to the load 306, and the negative terminal (-) thereof is coupled to the voltage comparator 3008 (1). The reference voltage circuit 310 (1) has a reference The voltage vcau, its voltage value is much smaller than the supply voltage L and the load voltage VL, which is about 10 millivolts (mV). The negative terminal (-) of the reference voltage circuit 31 (1) will output an adjusted reference voltage Vl, and its value Is the difference between the load voltage ^ and the reference voltage VCAL1. The purpose of the reference voltage circuit 3 10 (1) is to eliminate the offset voltage (0ffset) caused by the difference in the physical characteristics of the voltage comparator 3 〇 8 (丨). voltage) (usually its value is + -5mV) 'caused by the uncertainty of the output of the voltage comparator 308 (1) to ensure that when the power supply voltage Vbi is equal to the load voltage \, the transistor ^ must be turned on. Voltage comparator 3 0 8 (1) compares the power supply voltage Vbi of the first battery 3 0 2 and adjusts the load voltage Vl ′, and outputs a control signal to control the operation of the transistor M1. Among them, the input voltage comparator 3 08 (1) The positive load adjusts the load voltage VL ', which is the load voltage VL minus the reference voltage. VCAU

541778

Bad. In this embodiment, when the power supply voltage vB1 is greater than or equal to the adjusted load voltage VL ', the voltage comparator 308 (1) will output a low-level control, the voltage VCL to the gate of the transistor M 1. Since the transistor M 1 of this embodiment is a transistor of the P channel, the low-level control signal vCL can turn the transistor M 丨 on. Conversely, when the power supply voltage VB1 is less than the adjusted load voltage vL, the comparator 308 (1) will output a high-level control voltage vCH to the transistor ^ gate, and turn off the transistor M 1. Because the reference voltage vCAu is added, when the value of the supply voltage VB1 and the load voltage VL are equal, the reference voltage ^ is adjusted to be less than the supply voltage VM of the battery 302. Therefore, the transistor M1-constant conduction-this voltage comparison The device 3 0 8 (1) will only turn off the transistor M1 when the supply voltage vB1 is less than the load lightning. 'vl 0f The following describes the working principle of the power supply device 300 (1) coupled to the first battery 3 〇2 and the power supply control device 1 300 (2) coupled to the second battery 304 in the third figure. And circuit operation. Suppose the load 306 is only equipped with the first battery 302. Regarding the power supply control device 300 (1), regardless of whether the transistor M1 is turned on, the power supply voltage ^ must be greater than or equal to the load voltage vL. Therefore, the input voltage of the positive input 螭 (+) of the input voltage comparator 308 (1) must be less than the supply voltage V Bi of the negative input terminal (_). Therefore, the voltage comparator 3 0 (1) outputs a low-level control voltage 1 to the gate electrode of the body M 1 to turn on the transistor M 1. As for the power supply control device 300 (2), the transistor M2 will maintain the last state, which may be on or off. It is assumed that the second battery 304 is switched to the transistor ^ {2 and the negative input terminal of the voltage comparator 308 (2)) at this time. At this time, when the power of the second battery 304 is supplied,

Page 10 541778 V. Description of the invention (8) When the voltage VB2 is greater than the supply voltage VB1 of the first battery 3 0 2, the voltage comparator 3 0 8 (2) is because the supply voltage VB2 of the second battery 30 4 is greater than the load voltage. The low-level control voltage Vu is output to the gate of the transistor M2, and the transistor M2 is turned on. At this time, since the transistors M1 and M2 are both on and the power supply voltage VB2 of the second battery 3 04 is greater than the power supply voltage VM of the first battery 3 02 at this time, the transistor M1 is in a reverse phase bias. Reverse bias state. At this time, a reverse current flowing from the source to the drain charges the first battery 3 02. The transistor M 1 is affected by the reverse current, and a voltage drop is generated between the source and the drain. When referring to the voltage VCAU, the input voltage of the positive input terminal (+) of the voltage comparator 308 (1) must be greater than the input voltage of the negative input terminal (-). Therefore, the voltage comparator 3 0 (1) will output the control voltage VCH to turn off the transistor M1. At this time, the second battery 3 0 4 completely supplies the power required by the load 3 06. It should be noted that the first battery 302 and the second battery 304, as described above, switch their power supply conditions, and the load 306, which switches their power source, is completely implemented by hardware circuits. It is not executed by a micro control unit controlled by a software program. Compared with the micro-control unit controlled by the software program, the hardware circuit starts and switches faster and requires a shorter response time. In this way, when two batteries are switched, the transient voltage shortage caused by the too long response time of the micro-control unit will not occur. Assume that the second battery 3 0 4 is unplugged at this time, and the load voltage of the load 3 6 decreases to the load voltage minus the reference voltage VCAU is smaller than the supply voltage VB1 of the first battery 3 0 2, and the voltage comparator 3 0 8 (1 ) Will turn on the transistor M1. At this time, instead, the first battery 3 2 completely supplies the power required by the load 3 06. Therefore, the power supply control devices 3 0 0 (1) and 3 0 0 (2) have approximately equivalent circuit characteristics of an ideal two

Page 11 541778 V. Description of the invention (9) The polar body is turned on by the transistor in the forward direction, and a reverse current is detected in the reverse direction to turn the transistor off. Therefore, when two batteries supply power to the load, the high-voltage battery will supply power first, and when the two batteries are equal in voltage, the two batteries will supply power in parallel together. It should be noted that the control power supply device of the present invention can add or remove any battery without warning, regardless of whether the battery was the power source of the load 306 at that time, without causing the load voltage to drop. There will be no power outages or crashes. [Effects of the Invention] The power supply control device for an electronic device equipped with multiple batteries disclosed in the above embodiments of the present invention uses a hardware circuit to control and switch the power supply status of the battery. The hardware circuit has a fast operation speed and a short response time. , The phenomenon of transient instability does not occur when switching the power supply of the battery. The control power supply device of the present invention uses a field effect transistor, so the problem of voltage drop can be reduced. In addition, the present invention does not use a micro control unit to reduce the complexity of the circuit and the manufacturing cost. In addition, the present invention uses an independent power supply control device for each battery to control the power supply status of the battery, and does not need to communicate with other battery-powered control devices. Therefore, it can increase or decrease the portability without restriction. The number of batteries that the device is equipped with. In addition, when the battery is inserted or removed, there will be no drop in the instantaneous load voltage. At this time, there will be no power outage and crashes. In summary, although the present invention has been disclosed as above with a preferred embodiment, it is not intended to limit the present invention. Anyone skilled in the art will not depart from it.

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541778 Schematic illustration, [Simplified description of the drawing] Figure 1 shows a circuit block diagram of a power supply control device used in a conventional portable device equipped with dual batteries. Fig. 2 is a circuit block diagram of another power supply control device used in a conventional portable device equipped with dual batteries. FIG. 3 is a circuit block diagram of a power supply control device for a portable device equipped with a dual battery according to the present invention. [Schematic label description]

1 02, 202, 302: First battery 1 04, 204, 30 4: Second battery 1 0 6, 2 6, 3 0 6: Load 2 0 8: Micro control unit 3 0 8 (1), 3 0 8 (2): Voltage comparator 3 10 (1), 310 (2): Reference voltage circuit Ml 'M2: Transistor

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Claims (1)

541778 VI. Scope of patent application 1. A power supply control device for an electronic device equipped with multiple batteries = to control the power supply status of a plurality of batteries, wherein the electronic voltage and the battery have-power supply · 'The power supply control —Electric crystal 'is connected to the battery and the electronic equipment respectively; A voltage comparison circuit is shown with a first-generation product tt, connected to a second signal input: the terminal is connected to the electric circuit, and the voltage comparison circuit is Basis; supply two = i:; :: voltage output-comparison signal to control the sonde of the transistor. 接: each: the battery is independent of the power supply control device and the electricity at or equal to the load voltage, The small voltage and the electrical performance of the electronic device are turned off when the power supply is not connected to the male transistor, and the battery and the electronic device are connected to the electronic device. The power supply control device described above, in which the city j device further includes a reference voltage circuit, which is divided into two and the first signal input terminal of the voltage comparison circuit; u voltage circuit has _ reference electric a, Xiao according to the reference as The load voltage minus the reference voltage : The value is based on the turn-on and turn-off of both the power supply voltage and the adjusted load voltage. When the power supply voltage is greater than the adjusted negative value, the :: crystal turns on the δ11 transistor, when the power supply voltage is less than Adjust the load power: 'Η page 15 541778 VI. When applying for a patent scope / beijing' j Turn off the transistor. 3. The power supply control device as described in item 2 of the scope of patent application, wherein the reference voltage is greater than an offset voltage of the voltage comparison circuit. 4. The power supply control device according to item 1 of the scope of the patent application, wherein the voltage comparison circuit is a comparator (c0parat 〇r), and the first signal input terminal of the voltage comparison circuit is the comparator Positive input terminal, and the second signal input terminal of the voltage comparison circuit is a negative input terminal of the comparator. 5. The power supply control device according to item 1 of the scope of the patent application, wherein the transistor system is a power metal oxide semiconductor field effect transistor (power MOSFET). 6. The power supply control device as described in item 5 of the scope of patent application, wherein the power metal-oxide semiconductor field-effect transistor system is a P-channel power metal-oxide semiconductor field-effect transistor, and its drain Drain is coupled to the battery, its source is lightly connected to the electronic device, and its gate is coupled to the signal output terminal of the voltage comparison circuit. 7 · The power supply control device as described in item 4 and item 6 of the patent application scope, wherein when the power supply voltage is greater than or equal to the load voltage, the comparator outputs a low-potential control signal to make the P channel power metallox The semi-conducting field-effect transistor is turned on. When the power supply voltage is less than the load voltage, the comparator outputs a high-potential control signal to turn off the P-channel power MOSFET. Page 16 541778 T \ V0658 (030509) CRF.ptc Page 18