KR100811791B1 - Battery charger - Google Patents

Abstract

A battery charger is provided to simplify structures of a constant voltage circuit and a constant current circuit, and to improve the operation reliability of the battery charger. A battery charger includes a constant voltage/current circuit unit(200) and a program control unit(300). The constant voltage/current circuit unit includes a reference voltage setting resistor(210), a switching transistor(230), and a constant voltage feedback resistor(240). A charge current is detected from the reference voltage setting resistor. The switching transistor is turned on or off so as to apply and break the charge current to a battery connection unit(400). A constant voltage of the constant current applied to the battery connection unit is detected from the constant voltage feedback resistor. The program control unit includes a microcomputer(310). The microcomputer breaks the charge current applied to the battery connection unit by turning off the switching transistor in breaking the charge current by monitoring the charge current of a charge line.

Description

Battery Charger {BATTERY CHARGER}

1 is a circuit diagram of a conventional battery charger

2 is a circuit diagram of a battery charger of the present invention

DESCRIPTION OF REFERENCE NUMERALS

20: constant current circuit part 30: constant voltage circuit part

200: constant voltage / constant current circuit part 210: reference voltage setting resistance

220: constant voltage / constant current IC 240: constant voltage feedback resistance

250: Shunt resistor 260: Rated current recognition and breaking resistance

310: Microcomputer

The present invention relates to a battery charger, and more particularly to a battery charger of a portable electronic device.

Currently, rechargeable batteries are being used in various portable electronic devices including mobile phones, personal digital assistants (PDAs), digital cameras, camcorders, and the like. Such a portable electronic device mainly uses a rechargeable secondary battery, and a charger is used to charge the battery of the portable electronic device using the secondary battery.

In the case of a mobile phone, when the battery is discharged, the user charges the mobile phone by charging the mobile phone to the desk charger connected to the jack of the battery charger or directly connecting the jack of the battery charger to the mobile phone.

Such a battery charger is provided with a microcomputer (MCU) for charge control. After the microcomputer senses whether or not the battery is installed, it judges the charged state of the charged battery and charges the mounted battery when charging is required.

In recent years, as a battery charger for charging a battery has been standardized, the use of a TTA certified charger has been increasing. The TTA certified charger has a 24-pin charging terminal installed on one side of the mobile phone The battery will be charged.

1, the conventional battery charger includes a rectifying / filtering circuit 11 for rectifying and outputting an AC power with a predetermined DC power supply, a pulse width modulation (PWM) circuit 12 for converting the rectified and filtered DC power into a PWM AC waveform, A signal generating unit (PWM) 12, an isolation transformer 13 for leading the power of the PWM AC waveform to the secondary side, and a rectifying circuit 14 for converting the PWM AC voltage induced in the secondary side to DC A switching mode power supply (SMPS) 10 comprising: A constant voltage circuit unit (30) which is turned on by a PWM control signal applied from the microcomputer (41) to maintain a rectified pulse DC voltage (charge voltage) of the secondary side of the isolation transformer applied as a battery; A constant current circuit part (20) controlled by the microcomputer (41) to maintain a constant charging current applied to the battery; A battery connection unit 50 for charging the battery with a constant charging voltage by the charging current and applying the battery ID transmitted from the identification terminal of the battery to the microcomputer 41; And a program controller 40 including a microcomputer 41 for controlling the respective components.

In the constant voltage circuit portion of the conventional battery charger configured as described above, the reference voltage setting and the charging voltage inspection are performed as follows.

[1. Reference voltage setting]

When the microcomputer 41 of the program controller 40 applies a low signal to PWM control the U1 / B 358 and the comparator OP32, the shunt regulator U2 (TL431) 33 A feedback transistor Q2 (ST2412) for outputting a feedback current while the reference voltage Vref of the U1 / B 358 (32) is set to a stable reference voltage of 2,49V by the reference voltage Vref of 2.49V The output voltage of the U1 / B 358 (32) is lower than the reference voltage (Vref) of the U2 (TL431) 33 by turning on the dummy DUMMY resistor R10 ) Is maintained.

[2. Charge Voltage Check]

As the output voltage of the U1 / B 358 (32) is maintained at 2.49V and the switching transistor Q1 (STC353) 34 of the charging line is turned on, the power supply voltage (VCC) And constitutes the constant voltage circuit unit 30 that allows the charging terminal voltage applied to the battery connecting unit 50 through the charging line to be 4.2 V (4.8 V-0.6 V). The microcomputer 41 checks the charging terminal voltage applied to the charging line by the feedback current of the feedback transistor Q2 (ST2412, 31).

[Problems of Constant Voltage Circuit]

However, in such a conventional constant voltage circuit portion, Q2 (ST2412) 31 is turned on by U1 / B 358 (32), which is a comparator (OP Amp), and Q2 (358) 32 or Q1 (STC 353) 34 is inoperable or ineffective due to the complex circuit structure of the turn-on operation of the individual devices being turned on When a malfunction occurs, since the feedback current is not applied to the microcomputer, the charging terminal voltage can not be checked, and since the charging terminal voltage is 4.2 V (STC353) 34 is not turned on Can not be maintained. That is, the discrete device has a high failure rate (malfunction or malfunction) during long-term use or impact, which lowers the operational reliability of the battery charger.

In the constant current circuit of the conventional battery charger configured as described above, the current charge cut-off (CUTOFF) at the time of full charging is performed as follows.

[1. Current cut off by voltage recognition at full charge current (CUTOFF)]

The microcomputer 41 of the program control unit 40 determines whether the rated current of the battery is equal to or higher than 450 mA through the resistance value of the identification terminal (ID terminal) of the battery mounted in the battery connection unit 50 input at the first port (BATT ID) Or 750 mA current to control the selected rated current to flow. The operational amplifiers (OP Amp) U1 / A (358) and (21), which are discrete elements, control the shunt resistor Shunt Resistance (R32, R19, R23) 22 is amplified from 0.0 V to 3.0 V and outputted. At this time, the microcomputer 41 continuously receives the voltage amplified by the operational amplifiers (OP Amp) U1 / A 358 and 21 through the port 9 (BATT_CURR) and monitors the charging current of the charging line.

The microcomputer 41 monitors the charging current in this way, recognizes the amplified output voltage at a set time (for example, when the charging current is 70 mA) depending on the gradually decreasing charging current while being charged with the battery, (STC353) 34 of the charge line by turning off the feedback transistor Q2 (ST2412) 31 by turning off the feedback transistor Q2 (ST2412) 31 by outputting a HIGH signal through the port 15 The charging operation is cut off (CUTOFF) to complete the current charging operation.

[2. Problems of Constant Current Circuit]

However, in the conventional constant current circuit unit 20, the operational amplifier (OP Amp) U1 / A (358) and (21) is a discrete element having a high failure rate (malfunction or malfunction) If a malfunction occurs, the microcomputer can not control the rated current (450 mA or 750 mA) to flow, resulting in poor quality. On the other hand, due to the addition of peripheral passive elements for the constant current circuit configuration, The size of the substrate is increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and its main object is to simplify the structure of a constant voltage / constant current circuit and improve the operational reliability of the battery charger.

According to an aspect of the present invention, there is provided a battery charger for charging a battery of a battery connection unit by a charging current (battery rated current) output from a switching mode power supply unit and flowing to a charging line,

A switching transistor 230 that is turned on and off so that the charging current is applied to and disconnected from the battery connection unit 400 and a reference voltage setting resistor 210 for detecting the charging current, A shunt resistor 250 for detecting the charging current, a shunt resistor 250 for detecting the charging current, and a reference voltage setting resistor 210 for detecting a charging voltage of the charging current applied to the shunt resistor 250, And controls a voltage rating of the battery to be applied to the battery connection unit 400 to be constant when the switching transistor 230 is turned on and receives a voltage difference of the shunt resistor 250, A constant voltage / constant current circuit part 200 including a constant voltage / constant current control IC 220 for outputting a current through a rated current recognition and breaking resistor 260;

The charging current is applied to the battery connection unit 400 through the charging line by directly turning on the switching transistor 230. The charging voltage detected by the constant voltage feedback resistor 240, And receives a current outputted through the rated current recognition and blocking resistor 260 from the constant voltage / constant current circuit unit 200 and outputs a battery rated current flowing into the charging line Constant current control IC 220 to control the charging current of the charging line and to turn off the switching transistor 230 at the time of charging current interruption and to supply the charging current to the battery connection part 400 And a program controller 300 having a microcomputer 310 for shutting off a charging current.

Hereinafter, the technical composition of the present invention will be described in detail with reference to the accompanying drawings. FIG. 2 is a circuit diagram of a battery charger according to the present invention. As shown in FIG. 2, the switching mode power supply unit 100 of the present invention includes a rectifying / filtering circuit 110 for rectifying and outputting an AC power to a predetermined DC power source A pulse width modulation signal generating part (PWM) 120 for converting the rectified and filtered DC power into a PWM AC waveform, an isolation transformer 130 for leading the power of the PWM AC waveform to the secondary side, And a rectifying circuit 140 for converting the PWM AC voltage induced in the secondary side to DC.

The battery charger of the present invention further includes the program control unit 300 including the above-described switching mode power supply unit (SMPS) 100 and the constant voltage / constant current circuit unit 200 and the microcomputer 310 do.

The reference voltage setting resistors R5 and R10 and R6 and R11 of the constant voltage / constant current circuit unit 200 are connected in series to the output terminal of the switching mode power supply unit SMPS 100, And the switching transistor Q1 (STC353) 230 is connected to the charging line so that the charging current is turned on and off so as to be applied to and disconnected from the battery connection part 400, and the constant voltage feedback resistor 240 is turned on, R12 and R16, and R13 and R17 are connected in series to the rear end of the switching transistor Q1 (STC353) 230 and are connected in parallel to each other, so that the charging voltage of the charging current applied to the battery connecting portion 400 is detected, (250) R21, R22, and R23 are connected in series to the output terminal of the switching mode power supply unit (SMPS) 100 and are connected in parallel so that a charging current is detected.

The reference voltage setting resistors 210 R5 and R10 and R6 and R11 are connected to the VCTRL terminal of the constant voltage / constant current control IC 220. The shunt resistors 250, R21, R22 and R23 are connected to the LCTRL stage And the rated current recognition and blocking resistor R18 is connected in parallel to the VSENSE stage and the GND stage.

Therefore, the constant current / constant current control IC 220 receives the charge current detected by the shunt resistor 250 and the reference voltage setting resistor 210, and when the switching transistor 230 is turned on, (450 mA or 750 mA) of the battery to be applied to the microcomputer (400) through the rated current recognition and blocking resistor (260) according to the voltage difference of the shunt resistor (250) To the fifth port (CUR).

The switching transistor Q1 (STC353) 230 is directly connected to the fourth port (PWM) of the microcomputer 310 of the program controller 300. The constant voltage feedback resistors 240 and R16 and R13 and R17 Is connected to the port 9 (B +), and the remaining ports are connected to the battery connection unit 400.

Therefore, the microcomputer 310 directly turns on the switching transistor 230 to apply a charging current to the battery connection unit 400 through the charging line, and the charging current detected by the constant voltage feedback resistor 240 Constant current circuit unit 200 receives a current output through the rated current recognition and blocking resistor 260 and outputs the constant current / constant current control signal to the constant voltage / constant current circuit unit 200 based on the output current, The constant voltage / constant current control IC 220 controls the IC 220 so that the rated current of the battery flowing into the charging line is constantly controlled while monitoring the charging current of the charging line, 230 to turn off the charge current applied to the battery connection unit 400. [

The reference voltage setting and charge voltage inspection of the present invention configured as described above and the current charge cutoff (CUTOFF) at the time of full charge are performed as follows.

[1. Reference voltage setting]

The constant voltage / constant current control IC U1 (TSM1051) 220 detects the charging current flowing into the charging line as a voltage between the reference voltage setting resistors 210 and R10 and the voltage between both ends of R6 and R11 to generate a stable reference voltage of 2.49 V (VCTRL).

[2. Charge Voltage Check]

The switching transistor Q1 (STC353) 230 of the charging line, which serves to apply and disconnect the charging current to the battery connection unit 400, is turned on when the PWM control signal (port 4) output from the microcomputer 310 of the program control unit 300 is It is on when it is LOW, and off when it is HIGH. The Q1 (STC 353) 230 is turned on by the PWM control signal (port 4) of the microcomputer 310 so that the power supply voltage VCC of 4.8 V drops by 0.6 V to 4.2 V, Constant current control IC U1 (TSM1051) controls the charging voltage (battery rated voltage) 4.2V to be maintained constant.

Port 8 (B +, VBATT) of the microcomputer 310 of the program control unit 300 reads the battery voltage applied to the battery connection unit 400. The microcomputer 310 controls the constant voltage feedback resistance 240 ) R12 and R16 and the voltage between both ends of R13 and R17 are detected to check the charging voltage applied to the battery.

[Effects according to the constitutions of the above 1 and 2]

The present invention is not limited to the case where the charge current of the charge line for the charge voltage inspection is applied in accordance with the chain turn-on operation of the individual elements having a high failure rate (malfunction or malfunction) The microcomputer 310 which is a high integrated circuit IC can receive the charge current of the direct charge line and inspect the charge voltage and also the microcomputer 310 can directly detect the switching transistor Q1 (STC353) ( 230) can be turned on to maintain the charge terminal voltage at 4.2 V, thereby improving the operating reliability of the battery charger.

The reference voltage setting (U2 (TL431) 33) for turning on the feedback transistor Q2 (ST2412) 31 and the reference voltage holding for turning on the transistor Q1 (STC353) 34 (DUMMY) resistor 35) of the U2 (TL431) 33 and the dummy (DUMMY) resistor R10 35 do not depend on the reference voltage setting resistor 210 and the constant voltage / Constant current control IC U1 (TSM1051) 220, the circuit is simplified and the operation reliability of the battery charger is improved.

[3. Charge current cut-off by current recognition at full charge (CUTOFF)]

The port 6 of the microcomputer 310 of the program control unit 300 checks the identification terminal (ID terminal) of the battery mounted in the battery connection unit 400 and when the battery ID resistance value is 27 k? It is recognized that the rated current is 750 mA when 450 mA is 4.7 kΩ or 1.5 kΩ.

The charging current of 450 mA or 750 mA selected according to the recognized battery ID resistance value is compared with the shunt resistance (R21, R22, R23) 250 of the same resistance value as the conventional charging line, (R18) 260 (this resistor R18 recognizes the rated current (450 mA or 750 mA) flowing to the charging line and is a resistance which blocks the full charging of the rated charging current when fully charged) The microcomputer 310 controls the constant voltage / constant current control IC U1 (TSM 1051) 220 so that the constant voltage / constant current control IC U1 (TSM 1051) And controls the charging current of 450 mA or 750 mA to flow through the charging line.

The microcomputer 310 controls the constant current / constant current control IC U1 (TSM1051) 220 to control the charging current of 450 mA or 750 mA to flow through the charging line, When the rated current recognition and blocking resistor R18 260 is high impedance using the rated current sensing and blocking resistor R18 260 with the charging current flowing, Constant current control IC U1 (TSM1051)) 220 is charged with the battery by recognizing that 750 mA is flowing through the charge line when the constant voltage / constant current control IC U1 (TSM1051) The rated current of 450mA or 750mA is controlled to be constant.

The charging current of 450 mA or 750 mA flowing through the charging line according to the battery ID resistance value of the battery connection unit 400 is converted into the voltage difference by the shunt resistors R21, R22, The constant current control IC U1 (TSM1051) 220 recognizes and outputs a current corresponding thereto.

The output current is continuously input through the fifth port (CUR) of the microcomputer 310 through the rated current and the blocking resistor R18 260. The microcomputer 310 controls the charge current (PWM) for PWM control by recognizing the output current which varies depending on the gradually decreasing charging current when the battery is current-charged, and recognizes the output current at a predetermined time (for example, when the charging current is 70 mA) (STC353) 230 to turn off the current charging operation (CUTOFF), thereby completing the current charging operation.

[Effects according to the configuration of the above-mentioned 3]

A constant voltage / constant current control IC with high reliability for setting and maintaining the reference voltage of the constant voltage circuit portion rather than the discrete element U1 / A (358) having a high failure rate (malfunction or malfunction) (450mA or 750mA) can be controlled to flow, thereby improving the quality. In addition, since there is no need for a peripheral passive element for constituting the constant current circuit portion, the cost reduction and the circuit are simplified, and the size of the PCB substrate is reduced There is an effect that can be.

As described above, the microcomputer 310 of the program controller 300 of the present invention performs the following two control operations through the port CUR.

First, it controls the rated current according to the battery ID resistance value to flow through the charging line and controls the rated current to be kept constant.

Second, a control operation is performed to cut off (CUTOFF) the current charging operation when the rated current flowing to the charging line is fully charged.

The port 15 (G / LED) and the port 16 (R / LED) of the microcomputer 310 of the program control unit 300 determine the state of charge and the abnormality by controlling the LEDs, The internal temperature of the battery charger is checked to prevent damage to the main body of the cellular phone due to overheating, and the temperature is controlled so as to be charged normally.

As described above, the present invention is applicable to a constant voltage / constant current control IC (not shown), such as a reference voltage setting resistor 210, a constant voltage feedback resistor 240, a conventional shunt resistor 250, a rated current recognition and blocking resistor 260, Constant current circuit unit 200 including a constant voltage / constant current circuit unit 220 and a microcomputer 310 interlocked with the constant voltage / constant current circuit unit 200. The circuit structure is simplified, quality is improved, unit price is lowered, and operation reliability is improved.

Claims (1)

A reference voltage setting resistor 210 and a shunt resistor 250 output from the switching mode power supply unit SMPS and detecting a charging current (battery rated current) flowing to the charging line, and a shunt resistor 250 and the shunt resistor 250, A battery charger for charging a battery of a battery connection part by a constant voltage / constant current circuit part (200) including a constant voltage / constant current control IC (220) to which a charging current detected by a resistor (210) The constant voltage / constant current circuit unit 200 includes a switching transistor 230 connected in series to the charging line to turn on and off the charging current to be supplied to and disconnected from the battery connection unit 400, Constant current control IC 220 is connected to the battery connection part 400 when the switching transistor 230 is turned on, while the constant voltage / constant current control IC 220 further includes a constant voltage feedback resistor 240 for detecting a charging voltage of a charging current applied to the switching transistor 230, And receives a voltage difference between the shunt resistor 250 and a current sensing and blocking resistor 260 connected in parallel to the VSENSE stage and the GND stage, Output, The charging current is directly applied to the battery connection part 400 through the charging line by directly turning on the switching transistor 230 by the direct connection to the switching transistor 230, And the charging voltage (battery rated voltage) detected by the constant voltage / constant current circuit unit 200 is input to the constant voltage / constant current circuit unit 200. The constant voltage / constant current circuit unit 200 receives the current output through the rated current recognition / Constant current control IC 220 to control the charge current of the charge line by controlling the constant voltage / constant current control IC 220 to constantly regulate the battery rated current flowing into the charge line, and to turn the switching transistor 230 And a program controller (300) having a microcomputer (310) for turning off a charging current applied to the battery connection unit (400) Electricity.

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