KR19990001738A - Battery charge control device of portable terminal - Google Patents

Abstract

end. The technical field to which the invention described in the claims belongs

The present invention relates to a device for controlling charging of a battery used in a portable terminal.

I. The technical problem that the invention is trying to solve

Increase the efficiency by reducing the output port of the MPU of the terminal allocated for charging to one, and make the terminal more compact by moving the charging circuit in the terminal to the charger, and uniformity in brightness of the light emitting diode against component errors in the charger. It is to provide a battery charging control device of a portable terminal to give.

All. Summary of Solution of the Invention

In a device for controlling charging of the battery in a portable terminal using a constant voltage supplied from a charger as a main power source, the device is detected, and the voltage of the battery is detected and compared with a preset full charge voltage, and according to the comparison result It characterized in that it has a microprocessor unit for generating a control signal for switching the charging current of the battery to a rapid or trickle charging current through the output port of the transfer to the charger. The charger may include a diode connected to a charging terminal and configured to generate a predetermined voltage drop when the terminal is mounted, and a charging display to emit light in response to the voltage drop.

la. Important uses of the invention

Used to charge the battery of a portable terminal.

Description

Battery charge control device of portable terminal

The present invention relates to a battery charge control apparatus of a portable terminal.

Typically, cordless telephones use fast and quick trickle charging circuits, which control the charging is the microprocessor unit (hereinafter referred to as MPU) of the terminal.

1 illustrates a configuration of a conventional portable terminal and a charger, and is divided into a charger 200 and a part related to charging (hereinafter, referred to as a terminal for convenience) 300. The charger 200 includes an AC / DC adapter 100, a constant voltage source 20, a charging terminal (+,-), and a charging display unit. The charging display unit includes a diode D1, a resistor R1 for adjusting LED brightness, a transistor QLED, and a light emitting diode LED1.

The configuration of the terminal 300 is as follows. The charging terminal 40 is connected to the charging terminal 30 of the charger. The resistor Roff is a current adjusting resistor for fine charging with the battery BT when the terminal 300 is powered off. The MPU 50 has an input port rb for sensing battery voltage and two output ports P1 and P2 for controlling charging current. The first and second switches SW1 and SW2 are transistor switches, which are turned on or off by the fast charge control signal QCC and the trickle charge control signal TCC output from the MPU 50, respectively. For this control, the voltage at full charge is preset in the MPU 50. That is, the MPU 50 stops rapid charging and switches to trickle charging when the set value and the battery voltage read through the input terminal rb coincide with the quick charge control signal QCC and trickle charging in a predetermined state through the output ports P1 and P2. The first and second switches SW1 and SW2 are controlled by outputting the control signal TCC. Diode D2 prevents reverse discharge in case of shorting of charge terminals (+,-) 30.

As shown, the power is supplied from the AC / DC adapter 100 of the charger 200 and charged with the battery BT through the constant voltage source 20 and the charging terminal 40 of the terminal. At this time, the charging current is controlled by the first and second switches turned on or off by the quick charge control signal QCC and the trickle charge control signal TCC output from the MPU 50 of the terminal 300, respectively. In addition, this charging method is a constant voltage method through the constant voltage of the charger, the voltage is higher than the full voltage of the battery.

The current I flowing from the charger 200 to the light emitting diode LED1 may be represented by the following equation (1).

[Equation 1]

I = (Vd1-Vbe) / R1

Where Vd1 is the drop voltage of diode D1 and Vbe is the voltage difference between the base-emitter of transistor QLED. The resistance value R1 at this time is several tens Ω. In fact, the diode drop voltage has about 10% error in the reference specification and the voltage difference Vbe between the base and emitter of the transistor QLED also occurs. This will cause a large error in the current. When such an error occurs, the brightness of the light emitting diode visually confirmed while the light emitting diode is driven is not uniform for each set to be manufactured.

As a specific example, assume that there is no error, assuming that the resistance R1 is 10Ω, the diode drop voltage is 0.8V Q0.1V, and the voltage difference Vbe between the base-emitter of the transistor QLED is 0.6 Q0.1V. ,-If the maximum error has a current Iled corresponding to each can be represented as Equation 2 and 3.

[Equation 2]

Iled = (0.8-0.6) / 10 = 20 mA

[Equation 3]

Iled = (0.9-0.5) / 10 = 40 mA

In this way, if the current supply to the light emitting diode is about 2 times, a significant difference can be seen in visual confirmation, as well as a cause of failure in manufacturing the set. In addition, since the charging method is a constant voltage charging method, the life of the battery is shorter than that of the constant current charging method. In addition, it is contrary to the trend of miniaturization of mobile terminals, in which a charging circuit is embedded in the terminal, and the output port of the MPU is used one by one for rapid charging and trickle charging.

Therefore, an object of the present invention is to increase the efficiency by reducing the output port of the MPU of the terminal allocated for charging to one, and to make the terminal more compact by moving the charging circuit in the terminal to the charger, and to emit light on component errors in the charger. The present invention provides a battery charging control device for a portable terminal that gives uniformity to the brightness of an electrode.

1 is a block diagram of a conventional portable terminal and a charger

2 is a block diagram of a portable terminal and a charger according to an embodiment of the present invention

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals have the same reference numerals as much as possible even if displayed on different drawings. Also, in the following description, many specific details such as components of specific circuits are shown, which are provided to help a more general understanding of the present invention, and the present invention may be practiced without these specific details. It is self-evident to those of ordinary knowledge in Esau. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

2 is a block diagram of a portable terminal and a charger according to an exemplary embodiment of the present invention, and includes an AC / DC adapter 100, a charger 200, and a terminal 300.

First, the configuration of the charger 200 will be described. The light emitting diode LED emits light under predetermined control to indicate charging. The transistor QLED turns on when the terminal is mounted on the charger's charging terminal. Transistor Qz is for constant current supply. Zener diode Dz is connected to the AC / DC adapter 100 to implement a constant current circuit. Resistor R2 regulates the current supplied to the LED. Resistor R1 is for driving zener diode Dz. The constant voltage source 20 becomes a constant voltage source when the ground terminal GND is connected to ground, but when a predetermined resistor R is inserted between the ground terminal GND and the output terminal, the insertion resistance R is divided by the original constant voltage output Vo. . This constant current value Io can be expressed by the following equation (4).

[Equation 4]

Io = Vo / R

Therefore, the value obtained by dividing the constant voltage source output value by the parallel value of the resistors Rq, Rt, Rc and Roff according to the on / off of the charge switch transistors Qq, Qt and Qc becomes the charging current to be actually charged. Each of the charging switch transistors Qq, Qt, and Qc is switched in accordance with a logic signal provided by the terminal 300 described later. The diode D2 is a means for checking whether the terminal 300 is mounted in the charger 200 through the charging terminal 30. In other words, when the mounting is not performed, the voltage across the diode D2 is 0V, but when the terminal 300 is loaded on the charger 200, a drop of 0.8V is normally generated by the current, thereby turning on the transistor Qcr. Charging is indicated by turning on and emitting light. As a result, the diode D2 and the transistor Qcr are charging connection sensing means.

Next, the terminal 300 includes a rechargeable battery BT, a third switch SW3 and an MPU 50 for turning on / off the power of the terminal 300. The MPU 50 has an input port rb for sensing battery voltage and one output port P3 for controlling charging current.

Hereinafter, the operation of the embodiment of the present invention according to power on / off, rapid and trickle charging of the terminal 300 will be described.

The terminal 300 has two power modes and two charge modes. That is, the rapid or trickle charging mode in the power on mode and the trickle charging mode in the power off mode.

First, the logic and circuit operation required for charging will be described as follows.

First, when the terminal 300 is mounted in the charger 200 in the power-on mode and is rapidly charging, the output port P3 of the MPU 50 is in a high state. At this time, the transistor Qcr is turned on. Since the emitter voltage of the transistor Qc is always 0.6 V or more than the base voltage, the transistor Qc is always turned on when the terminal 300 is powered on. The voltage input to the AC / DC adapter 100 of the charger 200 is always greater than the logic high supplied by the terminal 300. Transistor Qq 'is turned on because it is high active, transistor Qa is turned on by turn-on of transistor Qq', transistor Qt 'is turned on by voltage supply as transistor Qc is turned on, and transistor Qt is turned on of transistor Qt' Is turned on. In the LED for charging display, the transistor Qcr is turned on as the diode D2 is dropped by 0.8V by mounting the charger 200 of the terminal 300, and the constant voltage output voltage is supplied from the emitter of the transistor Qcr to the base of the transistor QLED. The transistor QLED and the transistor Qz are turned on so that a current is supplied to the light emitting diode LED so that the light emitting diode LED is turned on.

At this time, the current supplied is a constant current, and the constant current value led can be represented by the following equation (5).

[Equation 5]

Iled = (Vz-Vbe) / R2

Vz: Zener Diode Voltage

Vbe: Drop voltage between base-emitter of transistor Qz

The current value given in Equation 5 is a form in which the current value change with respect to a component error is significantly improved compared to the circuit of FIG. 1 described above. Because the value of the zener diode voltage Vz is about 10 times the drop voltage Vbe between the base-emitter of transistor Qz and the absolute value of resistor R2 is several hundred Ω, the drop voltage Vbe between the base-emitter of transistor Qz is And the error of the zener diode voltage Vz are negligible compared to the resistance R2 value. And even if it has the same error as the conventional only has a maximum current error of about 10%. Therefore, the value of the rapid charge current is obtained by dividing the constant voltage output voltage Vo by the parallel values of the three resistors Roff, Rq and Rt. The battery charging current Ich1 at this time may be represented by the following equation (6).

[Equation 6]

Ich1 = Vo / (Roff // Rq // Rt)

Second, when the charger 200 is mounted on the terminal 300 in trickle charging mode, the output port P3 of the MPU 50 indicates a low state. That is, when the battery voltage is detected, the MPU 50 causes the output port P3 to be in a low state when the battery voltage is greater than the predetermined full charge determination value, thereby enabling rapid charging by opening the resistor Rq in the charger 200. Specifically, since the emitter voltage of the transistor Qc is always 0.6 V or higher than the base voltage, the emitter voltage is always turned on when the terminal 300 is in the on-mode. This is because the voltage input to the AC / DC adapter 100 of the charger 200 is always greater than the logic high supplied by the terminal 300. When the output port P3 of the MPU 50 is low, the transistor Qq 'is turned off. As the transistor Qq' is turned off, the transistor Qq is turned off. Transistor Qt 'is turned on by the voltage supply by the turn-on of transistor Qc, and transistor Qt is turned on by turn-on of transistor Qt'. At this time, the operation of the LED is the same as the first case described above. The trickle charge charging current Ich2 may be represented by the following equation.

[Equation 7]

Ich2 = Vo / (Roff // Rt)

Third, a case in which the terminal 300 is mounted in the charger 200 in the power off mode will be described. In this case, the control of the MPU 50 is impossible. Specifically, the output port P3 of the MPU 50 does not indicate any state of high or low. In the power-off mode, the transistor Qc of the charger 200 is turned off. Transistor Qq 'is turned off, thereby turning transistor Qq off. Transistor Qt 'is turned off by turning off transistor Qc, and transistor Qt is turned off due to turn off of transistor Qt'. At this time, the operation of the LED is the same as the first case described above. At this time, trickle charge as much as the charging current Ich3 shown in Equation 8 is maintained.

[Equation 8]

Ich3 = Vo / Roff

In the terminal power off mode, it is impossible to check the state of full charge and whether the battery is overcharged. Therefore, a small amount of battery is not damaged, that is, a trickle charge method is adopted.

The diode D2 in the charger 200 mentioned in the above description functions to turn on / off the resistor Qcr to determine whether the terminal 300 is mounted in the charger 200. The anode voltage of the diode D2 is applied to the base of the transistor QLED as it is.

In general, the constant voltage source output voltage in the charger is about 2 to 3 times the terminal operating voltage. Therefore, the resistors operating in each charging mode in the charger 200 are as follows. That is, the resistors Roff, Rq, and Rt operate during rapid charging in the power-on mode. During trickle charging in the power-on mode, the resistors Roff and Rt operate. The resistor Roff operates when charging in the power-off mode.

The power off mode performed in the terminal 300 is to completely open the load of the battery BT, and there is no control regarding charging. On the contrary, in the power-on mode, the MPU 50 of the terminal 300 senses the battery voltage through the input port rb and compares it with the internally determined full voltage level. Logic high is output through output port P3 to maintain fast charge.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by the equivalents of the claims.

The present invention as described above has the advantage that the output circuit of the MPU by reducing the output port of the MPU required to control the same charging function to one by having the charging circuit in the terminal in the conventional charger to increase the efficiency. In addition, it is effective in reducing the size and weight of a portable terminal. In addition, by implementing a constant current circuit using a transistor and a zener diode in the light emitting diode driving method in the charger, there is an advantage of uniformity of illuminance of the light emitting diode and minimization of defect rate in mass production of the product. The constant current source is implemented as a low-cost constant voltage source, and thus, the battery has a constant current charge, thereby extending the life of the battery relative to the constant voltage charging method.

Claims (5)

In the device for controlling the charging of the battery in a portable terminal using a constant voltage supplied from the charger to the battery as a main power source, Detects the voltage of the battery and compares it with a pre-set full charge voltage, and generates a control signal for switching the charging current of the battery into a rapid or trickle charging current through one output port according to the comparison result. And a microprocessor unit for delivering. The method of claim 1, wherein the charger, A diode connected to a charging terminal and detecting a mounting of the terminal to cause a predetermined voltage drop; And a charging display for emitting light in response to the voltage drop. The method of claim 1, wherein the charger, A parallel transistor corresponding to a plurality of modes is connected between an output terminal of the constant voltage source and the charging terminal, and a transistor for controlling its operation is connected to each resistor, and a specific transistor is responded to in response to a control signal generated from the microprocessor unit. Is switched so that a current corresponding to the mode flows to the output terminal. The method of claim 3, The mode is rapid and trickle charging in power on mode and charging in power off mode. The method of claim 2, wherein the charge display unit, With light emitting diode, Zener diode connected to AC / DC adapter, A terminal connected to the zener diode to regulate a current supplied to the light emitting diode; And a transistor connected between the resistor and the light emitting diode to supply a constant current to the light emitting diode.