JPH08191545A - Toggle-type power switching circuit - Google Patents

Abstract

PURPOSE: To provide a power switching circuit for a portable equipment which prevents a main circuit from being turned off even if there is an instantaneous cut-off of power while the equipment is in a stand-by condition. CONSTITUTION: This is a toggle-type power switch circuit with a resetting function which has a time constant circuit constituted of a diode 10 and a capacitor 9. The toggle-type power switch circuit is connected to a battery power supply for portable electronic equipment and serves for connecting the voltage of the power supply to a main circuit of the portable electronic equipment. A voltage detector 8 detects the voltage of the power line of the toggle- type power switch circuit and then resets a toggle-type power switch. The diode 10 is connected to an input terminal of the voltage detector 8 and delays the delivery of a signal for a short-time fluctuation of the power line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flip-flop type power switch circuit called a toggle type switch, and more particularly to a toggle type power switch circuit used in portable electronic equipment such as a mobile phone.

[0002]

2. Description of the Related Art Recently, in battery-powered portable electronic devices such as mobile phones, which have become popular, battery over-discharging or devices are adjusted according to the discharge end voltage of the battery or the drivable voltage of the circuit in the device. In order to prevent the erroneous operation, the switch circuit for detecting the battery voltage and cutting off the power supply of the main circuit is generally incorporated. In this case, for example, even if the battery is replaced or charged and the battery voltage rises and returns to the normal voltage, the main circuit remains powered off so that no malfunction occurs. Then, the power is not turned on to the main circuit unless the power switch is turned on again.

[0003]

However, in the conventional power switch circuit as described above, the power supply is momentarily cut off (instantaneous disconnection) due to unstable contact of the power supply terminals connecting the battery side and the apparatus main body side. If that happens, the number 1
There is an inconvenience that the main circuit remains powered off due to a momentary interruption of a short time width of 0 μs to several ms. The same applies to general electronic devices, but more specifically, it stands by (waits for reception) especially in mobile phones.
If this phenomenon occurs in the state, there is a problem that the power may be turned off without the user's knowledge, and a problem that an incoming call cannot be made may occur. The above-mentioned contact instability of the power supply terminals is caused by contact bouncing due to vibration or the like or contact failure due to adhesion of foreign matter. It is caused by the current of the circuit.

[0004]

A toggle type power switch circuit according to the present invention has a reset function for connecting to a battery power source of a portable electronic device and connecting the voltage of the power source to a main circuit of the portable electronic device. In a toggle type power switch circuit, a time constant circuit is provided which is connected to an input terminal of a voltage detector that detects a voltage of a power line and resets the toggle type power switch. The time constant circuit of the toggle type power supply switch circuit is preferably a delay circuit including a diode and a capacitor or a delay circuit including a resistor and a capacitor. The time constant circuit described above is preferably applied to, for example, a mobile phone.

[0005]

In the present invention, since a time constant circuit composed of, for example, a diode and a capacitor is provided between the input terminal of the voltage detector for detecting the voltage drop of the power supply line of the power supply switch circuit and the power supply line, a relatively long time is provided. Even if a momentary power failure occurs, the flip-flop element forming the toggle type power switch circuit is not reset, and therefore the main circuit is not turned off. In other words, this configuration
Strong against power interruptions. In other words, it has the function of detecting the voltage drop of the power supply line, but if the speed of the voltage drop is high, such as a momentary power failure, the detection is delayed with a larger time constant so that The circuit is prevented from performing unnecessary OFF operation.

[0006]

【Example】

(First Embodiment) FIG. 1 is a circuit diagram showing an embodiment of a power switch circuit according to the present invention. In FIG. 1, reference numeral 1 denotes a battery (not shown) used as a power source for a mobile phone, for example, which supplies power to the inside of the mobile phone body including a power switch circuit via a battery connection terminal 2. Reference numeral 3 denotes a power switch, one terminal of which is grounded, the other terminal thereof is connected to the Schmitt trigger input inverter 4, and the output thereof is connected to the clock input C of the D type flip-flop 5. The data input D of the D-type flip-flop 5 is connected to its q output, and the Q output is O of the voltage regulator 6.
It is connected to the N / OFF switch terminal SW. Note that the above-mentioned "q output" is a term intentionally used in this specification because it is designated as an unusable character in an electronic application such as the present application, and it is one of the two stable state outputs of the flip-flop element. Means the other inverted output corresponding to the Q output of one output of the above, and generally corresponds to the circuit symbol displayed in the form of the letter Q being overlined with a- (bar). (See note in Figure 1).

On the other hand, the output of the voltage detector 8 is connected to the reset terminal R of the D-type flip-flop 5 via the inverter 7, and its input is connected to the power supply line via the diode 9 together with the capacitor 9. . A series circuit of the capacitor 9 and the diode 10 constitutes a delay circuit (time constant circuit). With the above circuit configuration, the toggle type power supply switch circuit with the reset function according to the present invention is formed.

Here, the operation in the above-described circuit configuration will be described first, and subsequently, the operation in the case of the occurrence of a momentary interruption of the power supply line will be described with reference to the waveform diagram shown in FIG. Here, FIG. 2 is a waveform diagram showing voltage waveforms at the time of operation in each line indicated by reference signs a to g in FIG.

First, when the battery 1 is connected to the battery connection terminal 2, power is supplied to the V _DD terminal (not shown) of the D type flip-flop 5. On the other hand, "H" is input to the reset terminal R of the D-type flip-flop 5 for a certain period of time by the delay circuit formed by the diode 10, the capacitor 9, the voltage detector 8 and the inverter 7, and the D-type flip-flop is The Q output of 5 is set to "L" in the initial state. As a result, ON / O of the voltage regulator 6
"L" is input to the FF switch terminal SW, the output of the voltage regulator 6 is turned off, and the main circuit (not shown) connected thereafter (the arrow at the right end of FIG. 1) remains in the off state. .

In this state, turn off the power switch 3 →
When “ON” → “OFF”, the input of the Schmitt trigger input inverter 4 becomes “H” → “L” → “H”. Therefore, “L” → “H” → “L” is input to the clock terminal C of the D type flip-flop 5, the Q output is changed from “L” to “H”, and the q output / data input D is changed from “H”. "L"
Then, the voltage regulator 6 is turned on, which turns on the main circuit. That is, the mobile phone (not shown) is in an operable or usable state.

When the main circuit is in the ON state, that is, the Q output of the D-type flip-flop 5 is "H", the voltage of the battery 1 changes to the voltage of the voltage detector 8 due to, for example, long-term use of this mobile phone. When the detection voltage V _DET + the forward voltage V _F of the diode 10 is dropped, the output of the voltage detector 8 becomes “H” → “L”, the output of the inverter 7 becomes “L” → “H”, and the D type Flip flop 5
"H" is input to the reset terminal R of and the Q output is "L"
Therefore, the voltage regulator 6 is turned off, which turns off the main circuit. In other words, the step of detecting that the voltage of the battery 1 becomes lower than the specified value and warning that the battery needs to be charged or replaced, for example, is entered.

Here, the main circuit as described above is in the ON state,
That is, the Q output of the D type flip-flop 5 is "H".
In this state, when the battery connection terminal 2 is momentarily cut off, the voltage of the power supply line is equal to the capacitance C _{1 of the} capacitor (not shown) connected to the power supply line and the equivalent resistance R ₁ of the load. It falls due to the time constant τ ₁ due to the product (a waveform in FIG. 2). On the other hand, the input voltage of the voltage detector 8 (see FIG.
(E waveform) is separated from the power supply line by the diode 10, and therefore drops due to the time constant τ ₂ of the capacitance C _{2 of the} capacitor 9 and the input resistance R _{2 (} not shown) of the voltage detector 8. At this time, normally, R ₁ << R ₂
τ ₁ (= C ₁ R ₁ ) << τ ₂ (= C ₂ R ₂ ). Therefore, even if the power supply is interrupted for a relatively long time, the input voltage of the voltage detector 8 does not fall to the detection voltage (waveform f in FIG. 2), and therefore the D type flip-flop 5 is not reset. (G waveform in FIG. 2), the Q output remains "H" and the main circuit latches the ON state. That is, the inconvenience that the power of the main circuit remains disconnected due to the instantaneous power failure as described above is solved.

(Second Embodiment) FIG. 3 is a partial circuit diagram showing another embodiment of the power supply switch circuit according to the present invention. In the embodiment circuit diagram of FIG. 3, a resistor 11 is used instead of the diode 10 employed in the embodiment circuit diagram of FIG.
It has been configured using. Then, only the circuit system portion related to the resistor 11, that is, the voltage detector 8, the inverter 7, the capacitor 9 and the D-type flip-flop 5 are described, and other components are not shown. Therefore, the configuration of the present embodiment is almost the same as the configuration of FIG. 1 except for the above-mentioned changed parts.

Also in this embodiment, as in the case of the first embodiment, when the power supply is interrupted, the voltage of the power supply line is the capacitance C of the capacitor (not shown) connected to the power supply line. _It falls by the time constant τ _{1 which} is the product of ₁ and the equivalent resistance R ₁ of the load. On the other hand, the voltage detector 8
Input voltage of the capacitor C ₂ and the voltage detector 8
It falls by the time constant τ ₃ by the combined resistance R _{3 of the} input resistance R _{2 (} not shown) and the resistance R of the resistance 11. At this time, since R ₁ << R ₃ is normally satisfied, τ ₁ (= C ₁ R
₁ ) << τ ₃ (= C ₂ R ₃ ). Therefore, even if the power supply is interrupted for a relatively long time, the input voltage of the voltage detector 8 does not fall to the detection voltage, and the D type flip-flop 5 is not reset. ", And the main circuit latches the ON state. That is, as in the case of the embodiment of FIG. 1, the inconvenience that the main circuit remains powered off due to a momentary power failure is resolved.

As described above with reference to the first and second embodiments, for example, a diode and a capacitor are provided between the input terminal of the voltage detector for detecting the voltage drop of the power supply line of the power switch circuit and the power supply line. By providing the time constant circuit (first embodiment) composed of or the time constant circuit (second embodiment) composed of a resistor and a capacitor, even if a power interruption occurs for a relatively long time. The flip-flop element that constitutes the toggle-type power switch circuit is not reset, and therefore the main circuit is not turned off. In other words, this configuration makes it resistant to momentary power interruptions. Therefore, the inconvenience that the power supply of the main circuit remains disconnected due to the power supply interruption is solved,
It is possible to obtain an advantageous effect in use, which eliminates the problem that the mobile device is powered off without the user's knowledge and the incoming call cannot be received.

In the first and second embodiments described above, the case where the toggle type power switch circuit according to the present invention is applied to a mobile phone has been described, but the present invention is not limited to this, and it may be, for example, a personal computer, a modem or a video. It is also applicable to portable devices such as cameras, and devices using a toggle-type power switch with a reset function for vehicle-mounted electronic devices such as car phones, car stereos, and radar detectors.

[0017]

As described in detail above, according to the present invention, a time constant circuit having a simple component structure between the input terminal of the voltage detector for detecting the voltage drop of the power supply line of the power supply switch circuit and the power supply line. Since the power supply line of the applicable portable electronic device is interrupted for a relatively long time, the flip-flop element that constitutes the toggle-type power switch circuit is not reset. Do not turn off the main circuit. Therefore, this configuration eliminates the inconvenience that the power supply is tolerant to momentary power interruptions and the main circuit power remains disconnected due to momentary power interruptions. Is turned off, which eliminates the problem that the incoming call cannot be received, which is advantageous in terms of cost and use.

[Brief description of drawings]

FIG. 1 is a partial circuit diagram showing an embodiment of a power switch circuit according to the present invention.

FIG. 2 is a voltage waveform diagram during operation in each line indicated by reference signs a to g in FIG.

FIG. 3 is a partial circuit diagram showing another embodiment of the power switch circuit according to the present invention.

[Explanation of symbols]

 1 Battery 2 Battery Connection Terminal 3 Power Switch 4 Schmitt Trigger Input Inverter 5 D Type Flip Flop 6 Voltage Regulator 7 Inverter 8 Voltage Detector 9 Capacitor 10 Diode 11 Resistor

Claims (4)

[Claims] 1. A toggle-type power switch circuit with a reset function, which is connected to a battery power supply of a portable electronic device and connects the voltage of the power supply to a main circuit of the portable electronic device, detects the voltage of a power supply line. A toggle-type power switch circuit, which is connected to an input terminal of a voltage detector that resets the toggle-type power switch and is provided with a time constant circuit for short-term fluctuations of the power line. 2. The toggle type power switch circuit according to claim 1, wherein the time constant circuit is a delay circuit including a diode and a capacitor. 3. The toggle type power switch circuit according to claim 1, wherein the time constant circuit is a delay circuit including a resistor and a capacitor. 4. The toggle type power switch circuit according to claim 1, wherein the portable electronic device is a mobile phone.