JPH0543787U - Electronic equipment power supply - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a power supply device for an electronic device that supplies a stable voltage to a load in a power supply device that switches connection of a plurality of DC / DC converters according to a battery voltage. A step-down DC / DC converter that converts a battery voltage into a predetermined voltage and supplies the load to a load, and a step-up DC / DC converter are connected in a power supply device according to the battery voltage. After the second control signal for instructing the connection with the up-system DC / DC converter is output once, the first control signal for instructing the connection between the battery and the step-down system DC / DC converter is provided only after the battery replacement. Enable output.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a battery-powered portable computer or a power supply device for electronic equipment such as an information terminal device.

[0002]

[Prior Art]

 Conventionally, a dry battery (1.5 volt or a voltage that is an integral multiple of this) is used as the main power source of a notebook computer or an information terminal device that is often carried and used. The DC converter steps up (steps up) or steps down (steps down) to supply the DC 5V voltage required for driving the microprocessor and memory.

Therefore, in order to extend the life of the dry battery, which is the main power source, a step-up type and step-down type DC / DC converter is used, and when the dry battery voltage is in the initial state, it is connected to the step-down type DC / DC converter. When the battery voltage dropped, the DC / DC converter was switched to the step-up method to extend the battery drive time.

[0004]

[Problems to be solved by the device]

 However, according to the above-mentioned conventional method, since the connection between the step-up DC / DC converter and the step-down DC / DC converter is switched by the detected dry battery voltage, the dry battery voltage is near the connection switching voltage. If the power switch of the power supply device is turned on at this time, a chattering phenomenon occurs between the DC / DC converters of both due to fluctuations in the battery voltage, fluctuations in the supply voltage to the load, and superimposition of noise on the supply voltage. Occurred, which adversely affected the load on the microprocessor and memory.

The present invention has been made in view of the above problems, and it is an object of the present invention to supply a stable voltage to a load in a power supply device that switches connection of a plurality of DC / DC converters according to a battery voltage. To aim.

[0006]

[Means for Solving the Problems]

 The present invention relates to a battery for operating an electronic device, a step-down DC / DC converter selectively connected to the battery, converting a battery voltage into a predetermined voltage and supplying the load, and a step-up DC / DC converter. And a battery voltage detection circuit for detecting the battery voltage, and when the detected voltage by the battery voltage output circuit is in an initial state, commands the connection between the battery and the step-down DC / DC converter. A control signal is output, and when the detected voltage is in a second state in which the voltage is lower than the initial state, a second control signal for instructing connection between the battery and the step-up DC / DC converter is output. Further, after the output of the second control signal, the state circuit is capable of outputting the first control signal only after the battery is replaced.

[0007]

[Action]

 According to the present invention, after the second control signal for instructing the connection between the battery and the step-up DC / DC converter is output once, the connection between the battery and the step-down DC / DC converter is instructed. Since the first control signal can be output only after the battery is replaced, the chattering phenomenon does not occur between the two DC / DC converters due to the fluctuation of the battery voltage.

[0008]

【Example】

 The present invention will be described below with reference to the drawings showing an embodiment thereof.

FIG. 1 is a schematic configuration diagram of a power supply device of the present invention. In the figure, reference numeral 1 denotes a battery for driving an electronic device such as a portable computer or a terminal device, and usually a plurality of 1.5 V dry batteries are used together in many cases. In this embodiment, four (6 V rated) dry batteries connected in series are used. A battery voltage detection circuit 2 is connected to the high voltage side of the battery 1 and detects the voltage of the battery 1, and is composed of a comparator. This comparator 2 judges whether or not the voltage of the battery 1 is 5.5 V or less, and if it is 5.5 V or less, it outputs a Low signal to the state circuit 3 described later.

The state circuit 3 is composed of a flip-flop 4, a resistor 5 and a capacitor 6. A resistor 5 and a capacitor 6 connected in series are connected in parallel to the battery 1 and are connected to the set terminal of the flip-flop 4. The voltage output of the capacitor 6 is input, and the output of the comparator 2 is input to the reset terminal. It should be noted that both the set terminal and the reset terminal become active by inputting a Low signal.

The comparator 2 and the flip-flop 4 are operated by a voltage supply of 2.5 V or more, and the operating voltage is directly supplied from the battery 1.

When a Low signal is input to the set terminal or the reset terminal of the flip-flop 4, a Hi signal (control signal) from the Q terminal or the inverted Q terminal is output to the step-down DC / DC converter 7 or to the step-up type. It is input to the DC / DC converter 8.

Reference numeral 9 denotes a power switch of the power supply device. When the power switch 9 is turned on, the DC voltage of the battery 1 is input to the step-down DC / DC converter 7 and the step-up DC / DC converter 8.

The step-down DC / DC converter 7 is connected to the high voltage side of the battery 1 in accordance with the input of the Hi signal (first control signal) from the Q terminal of the flip-flop 4, and the direct current obtained from the battery 1 is obtained. The DC / DC converter 8 for step-up converts the 5.5 to 6.0 V voltage into a stable DC 5 V voltage and supplies it to the load 10. The step-up DC / DC converter 8 has an inverted Q terminal of the flip-flop 4. Is connected to the high voltage side of the battery 1 according to the input of the Hi signal (second control signal), the DC 3.6 to 5.5V voltage obtained from the battery 1 is converted into a stable DC 5V voltage and supplied to the load 10. It is a stabilized DC power supply circuit.

Next, the operation of the above embodiment will be described.

In the above embodiment, when a new dry battery (rated 6V) is set in the battery 1, the operating voltage is supplied to the comparator 2 and the flip-flop 4. Since the voltage output of the capacitor 6 is initially 0V, the Low signal is input to the set terminal of the flip-flop 4, and the Hi signal is output from the Q terminal to the step-down DC / DC converter 7. Then, according to the input of the first control signal to the step-down type DC / DC converter 7, the step-down type DC / DC converter 7 is brought into an operable state by being connected to the high voltage side of the battery 1.

Next, by turning on the power switch 9, the 5V output voltage of the step-down DC / DC converter 7 is supplied to the load 10. While the output voltage of the battery 1 is 5.5 V or more, the Low signal is not output from the comparator 2 and the Hi signal is still output from the Q terminal of the flip-flop 4, so this state is maintained. ..

After that, when the output voltage of the battery 1 drops to 5.5 V or lower (second state), the Low signal is output from the comparator 2 and is input to the reset terminal of the flip-flop 4. By this input, the Q terminal of the flip-flop 4 becomes a Low signal, and the Hi signal is output from the inverted Q terminal to the step-up DC / DC converter 8. Then, according to the input of the Low signal to the step-down DC / DC converter 7, the connection with the high voltage side of the battery 1 is released, and conversely, according to the input of the Hi signal to the step-up DC / DC converter 8, the battery is 1 is connected to the high voltage side, and the step-up type DC / DC converter 8 becomes operable. Then, this state is held until the Low signal is input to the set terminal of the flip-flop 4.

Therefore, except when the battery 1 is replaced, the step-up DC / DC converter 8 is connected and held on the high-voltage side of the battery 1 regardless of the fluctuation of the output voltage of the battery 1.

Then, the output voltage of 5V is supplied from the step-up DC / DC converter 8 to the load 10 until the output voltage of the battery 1 drops to 3.6V.

In the above embodiment, the case where the comparator 2 is used as the battery voltage detection circuit to detect whether the output voltage of the battery 1 is 5.5 V or lower and the connection of the DC / DC converter is switched is described. As described above, another battery may be used to detect whether or not the battery 1 has dropped to the minimum usable voltage of 3.6 V and cause the apparatus body to display the battery replacement.

Further, the case where the state circuit 3 is constituted by the flip-flop 4, the resistor 5, and the capacitor 6 has been described, but a CPU or the like is used, and a step-up type DC / DC circuit is used based on the output of the battery voltage detection circuit. The control signal may be output to the DC converter 7 and the step-down DC / DC converter 8.

[0023]

[Effect of the device]

 As described above, according to the present invention, a power supply for switching connection of a step-down DC / DC converter and a step-up DC / DC converter, which converts a battery voltage into a predetermined voltage and supplies the load, according to the battery voltage. In the device, after the second control signal for instructing the connection between the battery and the step-up type DC / DC converter is output once, the second command for instructing the connection between the battery and the step-down type DC / DC converter is issued. Since the 1 control signal can be output only after the battery is exchanged, even if the battery voltage is near the voltage for connection switching, the chattering phenomenon may occur between the DC / DC converters of both due to the fluctuation of the battery voltage. There is no.

Therefore, according to the power supply device of the present invention, it is possible to always supply a stable predetermined voltage to the load.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a power supply device according to an embodiment of the present invention.

[Explanation of symbols]

 1 Battery 2 Comparator (Battery Voltage Detection Circuit) 3 State Circuit 4 Flip-Flop 5 Resistor 6 Capacitor 7 Step-up DC / DC Converter 8 Step-down DC / DC Converter 9 Power Switch 10 Load

Claims (1)

[Scope of utility model registration request] 1. A battery for operating an electronic device, a step-down DC / DC converter which is selectively connected to the battery, converts a battery voltage into a predetermined voltage and supplies the load, and a step-up DC / DC. A converter, a battery voltage detection circuit for detecting the battery voltage, and the battery and the step-down DC / DC when the detected voltage by the battery voltage output circuit is in an initial state.
Outputs a first control signal for instructing connection with the converter,
When the detected voltage is in the second state in which the detected voltage is lower than the initial state, the battery and the step-up method D are used.
A state circuit which outputs a second control signal for instructing connection with a C / DC converter, and which, after the output of the second control signal, enables the output of the first control signal only after the battery is replaced. A power supply device for electronic equipment, characterized in that