JP2003167636A - Electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the reset of electronic equipment due to a rush current at turning ON a voltage regulator when power is supplied. <P>SOLUTION: At turning ON a voltage regulator REG 3 for supplying a constant voltage V3 to a display circuit 17, the REG 3 is turned ON/OFF in a short cycle, and then normally turned ON under the control of a control circuit 14. Thus, it is possible to reduce the rush current to a capacitor C3 when the power is supplied, and to suppress the deterioration of a power supply voltage VB due to the rush current, and to prevent a reset signal from being outputted from a voltage detecting circuit 15. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device, such as a mobile phone device, which operates with a removable battery as a power source, and more particularly to an electronic device characterized by voltage control when the power is turned on.

[0002]

2. Description of the Related Art A portable telephone device is a typical electronic device that operates using a battery as a power source. This portable telephone device is provided with a removable battery (secondary battery), and this battery voltage is converted into a constant voltage necessary for the operation of each circuit by a voltage regulator and supplied. The circuits include a control circuit including a CPU, a wireless circuit, a display circuit, and the like, and a voltage regulator is prepared for each of these circuits. These voltage regulators are provided with capacitors for oscillation prevention and voltage smoothing.

In addition, the portable telephone device is a battery (secondary battery) mounted in the device body by externally supplying power by connecting an adapter to a charging terminal provided in the device body.
It is possible to charge. Also, at the manufacturing stage, etc.
When writing the OM program, a dedicated device (R
Writing is performed without a battery by external power feeding from a charging terminal using an OM writer). When charging the battery with this external power supply, it is dangerous to charge rapidly with a low voltage, so it is necessary to gradually charge with a low current, and therefore a small voltage regulator with a smaller current capacity than the battery should be used. It is generally equipped for preliminary charging.

[0004]

For example, when a program is written in the ROM at the manufacturing stage, or when a new program is written at a store due to a version upgrade of the program, etc. Power supply. At that time, the power supply to the wireless circuit and the like unnecessary for writing the program is turned off, but the power supply to the display circuit is turned on in order to check the writing result on the screen. In other words, not only the voltage regulator for the control circuit, but
It is also necessary to turn on the voltage regulator for the display circuit.

However, in the case where power is supplied via the small voltage regulator for precharging by external power feeding, when the voltage regulator is turned on to operate the display circuit or the like, the capacitor connected to the voltage regulator. Inrush current flows to. In other words, when the device is off, the voltage supply to the voltage regulator is cut off, while the current flows through the load, the capacitor is discharged and becomes uncharged. Therefore, when the device is turned on in this state,
A large current will flow into the capacitor in a short time. When the inrush current at this time exceeds the supply current of the voltage regulator, the power supply voltage becomes lower than the reference voltage, resetting occurs, and there is a problem that the program writing fails.

The present invention has been made in view of the above points, and it is an object of the present invention to provide an electronic device capable of preventing the occurrence of resetting due to an inrush current when the voltage regulator is turned on when the power is turned on. .

[0007]

An electronic device according to the present invention is an electronic device which operates using a removable battery as a power source.
A voltage regulator capable of ON / OFF control by converting the power supply voltage of the battery into a constant voltage necessary for circuit operation and supplying the voltage regulator, and regularly turning ON / OFF the voltage regulator at a predetermined period when the power is turned on. And a control means for controlling to turn it on.

According to such a configuration, the voltage regulator is not switched from OFF to ON at a time when the power is turned on, but ON / OFF is repeated in a short cycle, and then control is performed so that the voltage regulator is constantly turned ON. As a result, it is possible to prevent the power supply voltage from decreasing due to the rush current and prevent the reset from occurring.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a circuit configuration of a power supply system in a portable telephone device which is a typical electronic device which operates by using a battery as a power supply.

The portable telephone device is provided with a removable battery (secondary battery) 11 in the main body of the device, and the external power supply terminal 1
2 has a structure capable of supplying power from the outside. Further, voltage regulators (hereinafter, referred to as REGs) 1 to 3 are incorporated in each circuit provided in the apparatus main body, and these REGs 1 to 3 convert the power supply voltage VB into a constant voltage necessary for circuit operation. It is configured to be supplied. Each of the REGs 1 to 3 has a control terminal for turning on only when it is necessary to reduce current consumption and turning it off when it is unnecessary.

REG1 receives the power supply voltage VB as an input,
A regulator for supplying the voltage V1 necessary for the operation of the control circuit 14 including the ROM 13 and the CPU, and starts the supply operation when the power switch (indicated by SW in the figure) of the device is turned on. Voltage detection circuit (DET) 15
Monitors the output voltage of REG1 and detects that the voltage has dropped below a preset reference voltage, the control circuit 14
A reset signal is output to urging the device to turn off. The REG2 is a regulator that receives the power supply voltage VB as an input and supplies the voltage V2 necessary for the operation of the radio circuit (RF) 16. The REG3 is a regulator for receiving the power supply voltage VB as an input and supplying a voltage V3 necessary for the operation of the display circuit 17. The REG2 and REG3 are ON / OFF controlled by the control circuit 14, respectively.

In addition, the portable telephone device has the above-mentioned R.
REG4 is provided separately from EG1 to EG3. This R
EG4 is a regulator for precharging the battery 11, and when the battery 11 is not attached, the external power supply terminal 12
It is used when the power supply voltage VB is supplied by the power supply from.

The REG1 for the control circuit 14, the REG2 for the radio circuit 16, the REG3 for the display circuit 17, and the REG4 for precharging the battery 11 have the outputs of REG oscillation prevention and voltage respectively. Capacitors C1 to C4 having a predetermined capacity are provided for smoothing. In the figure, R1 and R2 are resistors, and Di is a diode.

In such a structure, the battery 11 is usually mounted on the apparatus main body, and the power supply voltage V
B is supplied and each of the circuits 14 to 16 operates at a predetermined voltage. In this case, when the power switch (SW) of the device is turned on, REG1 is first turned on and the voltage of V1 is output from REG1. The control circuit 14 operates upon receiving the output of the voltage V1, and then the control circuit 14 causes the REG2 and REG to operate.
By turning on 3, the wireless circuit 16 displays V2 and the display circuit 1
7 is supplied with the voltage of V3. As a result, the wireless operation and the display operation are enabled.

On the other hand, in the manufacturing stage or the like, when the program is written in the ROM 13 by external power feeding without mounting the battery 11, the REG4 from the external power feeding terminal 12 is used.
When the power supply voltage VB is supplied via
Then, the voltage of V1 is output from this REG1 and the control circuit 14 operates. Further, since the wireless circuit 16 is not necessary when writing the program, REG2 is not turned on (OF
REG3 for the display circuit 17 is turned on in order to display the program writing result (success / failure).

Here, the REG 4 also has a function of pre-charging the battery 11, and the battery 11 is operated in a low voltage state.
In order to prevent the battery from being charged rapidly, a battery having a smaller current capacity than the battery 11 is used. On the other hand, as described above, when the power supply of the device is OFF, the capacitor is in an uncharged state, so when the power is turned on (when the device power is turned on), a rush current flows into the capacitor C3 connected to the REG3 all at once, and When the current exceeds the supply current of REG4, the power supply voltage VB temporarily drops.

When the power supply voltage VB drops, R
Since V1 output from EG1 also drops, the control circuit 14 is reset when the V1 falls below the reference voltage of the voltage detection circuit 15. When the voltage of VB is restored, the reset is released, but when REG3 is turned on again, the same phenomenon occurs, and therefore ON and reset are repeated, and it becomes impossible to write the program.

This situation will be described with reference to FIG.

FIG. 4 is a diagram for explaining power-on control according to the conventional method. Vt in the figure indicates the reference voltage set in the voltage detection circuit 15.

In the case where the power supply voltage VB is supplied to the apparatus by external power supply (without battery), the conventional method is
(1) When a voltage is applied to the external power supply terminal, REG1 is automatically turned on via the resistor R1.
When the control circuit 14 operates by receiving the voltage of 1, (2) the control circuit 14 turns on REG3. At this time, REG3
Since the capacitor C3 of is in an uncharged state, an inrush current flows there, and under the influence of this, VB decreases and V
1 decreases. (3) When V1 becomes lower than the reference voltage Vt of the voltage detection circuit 15, the voltage detection circuit 15 outputs a reset signal to the control circuit 14 to turn off the power supply. After that, with the recovery of VB, the above (1)-
(3) is repeated.

As described above, in the conventional method, there is a problem in that the power supply voltage VB is suddenly lowered due to the inrush current flowing to the capacitor C3 when the power is turned on and resetting occurs, so that the program cannot be written. It was happening.

Therefore, in the present invention, in order to solve such a problem, when REG3 is turned on, it is turned on in a short cycle.
After repeating / OFF (for example, ON: 10 μs, O
FF: 90 μs 100 times), control is performed such that it is constantly turned on. By controlling the ON / OFF of REG3 in a short cycle in this manner, it is possible to reduce the inrush current flowing to the capacitor C3, suppress the fluctuation of VB, and prevent resetting.

This situation will be described with reference to FIG.

FIG. 2 is a diagram for explaining the power-on control of the present invention. The control circuit 14 is provided with a function for controlling ON / OFF of the REG 3 in a predetermined cycle in advance. This ON / OFF control function can be realized by hardware using a timer, for example, or can be realized by software using a predetermined algorithm.

As shown in FIG. 2, external power supply (without battery)
When the power supply voltage VB is supplied to this device by
In the system of the present invention, (1) R is turned on by turning on the power switch.
When EG1 is turned on and the control circuit 14 operates by receiving the voltage of V1 from REG1, (2) the control circuit 14 becomes RE
G3 is turned on / off in a short cycle, and (3) REG3 is controlled to be constantly turned on after a predetermined period.

As described above, if the ON / OFF of the REG3 is repeated in a short cycle, the capacitor C3 connected to the REG3 is gradually charged, so that the rush current flowing there can be reduced. As a result, it is possible to prevent the reset from occurring due to the decrease in V1 accompanying the decrease in VB.

The period for turning ON / OFF the REG3 is obtained as follows.

Now, the period in which REG3 is turned ON is Ta, OF
The period of F is Tb, and the current flowing into the capacitor C3 is I
1. Let I2 be the current flowing in the display circuit 17 due to the discharge of the capacitor C3 and C be the capacitance of the capacitor C3.
As shown in, the voltage value ΔV obtained by turning ON / OFF once is calculated by ΔV = ΔVa−ΔVb = {(I1 / 2) × Ta} / C − {(I2 / 2) × Tb} / C To be ΔVa is a voltage corresponding to the amount of charge accumulated in the capacitor C3 during the ON period of REG3, and ΔVb is R
It is a voltage corresponding to the amount of charge discharged from the capacitor C3 during the OFF period of EG3.

Here, the period (number of times) n for turning ON / OFF the REG 3 is approximately obtained by a calculation such as n = Vmax / ΔV, where Vmax is a preset voltage level. Vmax above
For this, a value is used such that V1 does not fall below the reference voltage Vt of the voltage detection circuit 15 within the operating voltage range of the display circuit 17 due to the inrush current to the capacitor C3.

In this way, ON / OFF is repeated in a short cycle until V3 rises to Vmax, and then REG3
When is turned on, the control circuit 14 is not reset, so that the program can be normally written in the ROM 13 when the power is turned on by external power supply, for example, at the manufacturing stage.

Although the above embodiment has been described by taking the portable telephone device as an example, the present invention is not limited to this, and in general electronic equipment driven by a removable battery,
It is applicable when writing a program or performing an operation test without installing a battery.

[0033]

As described above, according to the present invention, for example, when a program is written in the manufacturing stage, the voltage regulator is turned on / off in a short cycle at power-on, and then the voltage regulator is constantly operated. Since the control to turn it on is performed, it is possible to prevent the power supply voltage from dropping due to the inrush current even without the battery, and thus to prevent the reset from occurring and to normally write the program. become.

[Brief description of drawings]

FIG. 1 is a diagram showing a circuit configuration of a power supply system of a general mobile phone device as an electronic device according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining power-on control (battery-less external power feeding operation) according to the present invention.

FIG. 3 is a diagram for explaining an ON / OFF period of the voltage regulator according to the power-on control of the present invention.

FIG. 4 is a diagram for explaining a conventional power-on control (battery-less external power feeding operation).

[Explanation of symbols]

1 to 4 ... REG (voltage regulator) 11 ... Battery (secondary battery) 12 ... External power supply terminal 13 ... ROM 14 ... Control circuit 15 ... Voltage detection circuit 16 ... Wireless circuit 17 ... Display circuit

Claims (2)

[Claims] 1. An electronic device which operates using a removable battery as a power source, and an ON / OFF controllable voltage regulator for converting the power source voltage of the battery into a constant voltage necessary for circuit operation and supplying the voltage, and turning on the power source. An electronic device, comprising: a control unit for controlling the voltage regulator to be constantly turned on after turning on / off the voltage regulator at a predetermined cycle. 2. The electronic device according to claim 1, wherein the control means turns ON / OFF at a predetermined cycle until the output voltage of the voltage regulator rises to a preset voltage level. .