JP2007037225A - Charging circuit and charge control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charging circuit of a constant current charge system which can surely charge a battery even in the case that a charger of, low charge current supply capacity is used, and a charge control method using the charging circuit. <P>SOLUTION: The charging circuit of the constant-current constant-voltage charge system, which is equipped at least with a charger detecting circuit 6, a charge current monitoring circuit 7, a power source for a constant current reference, a voltage monitoring circuit 8, a reference power source 11 for a constant voltage, a constant current constant voltage charging circuit 9, an FET 2, and a charge control circuit 12, is provided with a charger voltage monitoring circuit 5 which monitors the supply voltage of a charger. The circuit uses a D-A converter 10 for the constant current reference where a voltage value is variable as a reference power source for a constant current. In the case that a supply voltage on the charger side reaches a threshold or under, the circuit it adjusts the voltage of the D-A converter 10 for the constant current reference into a charge current fit for the charger thereby executing constant current saving charge. By this, the circuit can charge a battery without fail even in the case that the charger of the low current supply capacity is used. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a charging circuit and a charging control method using the charging circuit.

  There is a constant current constant voltage charging method as a method of charging a battery such as a mobile phone, and there is a charging circuit that charges the battery with a constant current charging method up to a certain battery voltage and then switches to the constant voltage charging method. It is known (for example, refer to Patent Document 1 below). FIG. 5 is a circuit diagram showing the configuration of a conventional constant current constant voltage charging system charging circuit, and FIG. 6 is a flowchart showing a charging procedure using the conventional charging circuit.

  As shown in FIG. 5, the conventional constant-current / constant-voltage charging circuit detects a battery 101 as a power source for a mobile phone, a connector 104 to which a charger is connected, and that the charger is connected. A charger detection circuit 106, a charging current detection resistor 103 for generating a potential difference by the charging current, a charging current monitoring circuit 107 for monitoring the charging current by the potential difference, and a reference for charging current adjustment during constant current charging A constant current reference power source 110, a voltage monitoring circuit 108 that monitors the voltage and charging voltage of the battery 101, a constant voltage reference power source 111 that serves as a reference for charging voltage adjustment during constant voltage charging, a constant current charging and constant power supply. A constant-current / constant-voltage charging circuit 109 that performs two types of charge control of voltage charging, an FET 102 that adjusts the charging current and the charging voltage, and a charging control that controls all of the charging circuits. Composed of such circuit 112.

  In the above charging circuit, as shown in FIG. 6, when a charger is connected to the connector 104, the charger detection circuit 106 detects the connection of the charger (S 201), and starts preliminary charging under the control of the charging control circuit 112. (S202). Then, it is determined whether the voltage value monitored by the voltage monitoring circuit 108 is a threshold level for shifting to constant current charging (S203). When the voltage value is equal to or higher than the threshold level, shifting to constant current charging is performed (S204). Next, it is determined whether the voltage value of the battery 101 monitored by the voltage monitoring circuit 108 is a threshold voltage level for transition to constant voltage charging (S205). Charging is performed (S206), and charging operation is performed until charging is completed (S207, S208).

JP 2004-222446 A (page 5-7, FIG. 1)

  In the above charging circuit, when charging with constant current charging, charging is performed with a constant large current in consideration of the charging time of the battery, but there are some commercially available simple chargers other than regular chargers. Some chargers do not have the ability to charge with a large current, and when using a charger with such a low charge current supply capability, the supply voltage on the charger side drops during constant current charging and falls below the chargeable voltage. The charging is stopped. When the charging is stopped, the supply voltage on the charger side is increased, and constant current charging is started. Therefore, the start / stop of charging is repeated and the battery is not charged.

  The present invention has been made in view of the above problems, and its main purpose is a constant current capable of reliably charging a battery even when a charger having a low charging current supply capability is used. An object of the present invention is to provide a charging system charging circuit and a charging control method using the charging circuit.

  In order to achieve the above object, the circuit of the present invention is a charging circuit that charges a battery by a constant current constant voltage charging method, and is configured such that the charging current during constant current charging can be switched according to the supply voltage of the charger. It is what.

  Further, the circuit of the present invention is a charging circuit for charging a battery by a constant current constant voltage charging method, and means for comparing the supply voltage of the charger with a predetermined threshold at the time of constant current charging, and the supply of the charger Means for switching the charging current of the constant current charging from the first charging current to the second charging current set according to the performance of the charger when the voltage is equal to or lower than the threshold; It is to be prepared.

  The circuit of the present invention includes a charger detection circuit for detecting a charger, a charging current monitoring circuit for monitoring a charging current, a voltage monitoring circuit for monitoring a battery voltage and a charging voltage, and a power source during constant current charging. Constant current reference power source, constant voltage reference power source for constant voltage charging, constant current constant voltage charging circuit for charging with constant current or constant voltage, and adjustment of charging current and charging voltage A constant current constant voltage charging system charging circuit comprising at least a charge control circuit for performing charge switching control, comprising a charger voltage monitoring circuit for monitoring a supply voltage of the charger, and the constant current reference The power source can be switched between a first charging current and a second charging current set according to the performance of the charger, and the charger voltage monitoring circuit preliminarily selects the supply voltage of the charger. Compared with a set threshold As a result, when the supply voltage of the charger becomes equal to or lower than the threshold, the charging control means switches the charging current for constant current charging from the first charging current to the second charging current. is there.

  In the present invention, the constant current reference power source may be a D / A converter.

  Moreover, in this invention, when the supply voltage of the said charger becomes below the said threshold value, it can be set as the structure which generates an interruption signal to CPU.

  Further, the method of the present invention is a charge control method using a charging circuit for charging a battery by a constant current constant voltage charging method, and is a control for switching a charging current during constant current charging according to a supply voltage of a charger. Is to do.

  Further, the method of the present invention is a charge control method using a charging circuit for charging a battery by a constant current constant voltage charging method, and the supply voltage of the charger becomes equal to or lower than a predetermined threshold during constant current charging. In this case, control is performed to switch the charging current of the constant current charging from the first charging current to the second charging current set in accordance with the performance of the charger.

  The method of the present invention is a charge control method using a charging circuit for charging a battery by a constant current and constant voltage charging method, wherein the step of charging with a first charging current and the supply voltage of the charger are measured. Comparing the supply voltage of the charger with a predetermined threshold, and when the supply voltage of the charger is equal to or lower than the threshold, the charging current for constant current charging is calculated from the first charging current. Switching to a second charging current set according to the performance of the charger, measuring a battery voltage, comparing the battery voltage with another predetermined threshold, and the battery voltage A step of switching to constant voltage charging when the threshold value is equal to or greater than another threshold value.

  Thus, according to the present invention, when the supply voltage on the charger side becomes equal to or lower than a predetermined threshold during constant current charging, the voltage value of the constant current reference power supply is adjusted to a voltage value suitable for the charging current. Thus, since the constant current saving charging is performed, the battery can be reliably charged without the supply voltage on the charger side being lowered and the start / stop of charging being repeated as in the conventional case. In addition, when the supply voltage on the charger side falls below a predetermined threshold, an interrupt signal is generated to the CPU, indicating that the charger being used is not a regular charger or that the charger is abnormal. This can be notified to the user.

  According to the charging circuit and the charging control method of the present invention, charging can be performed with an optimal charging current for a mounted charger without repeating the start / stop of charging, and the user can be informed of the malfunction. Can do.

  The reason is that the charger circuit is provided with a charger voltage monitoring circuit for monitoring the supply voltage on the charger side, the supply voltage on the charger side during constant current charging is monitored with the charger voltage monitoring circuit, and the charger side This is because, when the supply voltage reaches the threshold value or less, the constant current reference power supply voltage is adjusted to a voltage value suitable for the charger to perform constant current save charging.

  In addition, when the supply voltage on the charger side reaches the threshold value or less, an interrupt signal is generated for the CPU to confirm that the charger being used is not a regular charger or that the charger is abnormal. This is because control such as display on the display screen is performed.

  In a preferred embodiment of the charging circuit of the present invention, a battery serving as a power source, a connector to which the charger is connected, a charger detection circuit for detecting that the charger is connected, and a potential difference depending on the charging current. A charging current detection resistor for generating a charging current, a charging current monitoring circuit for monitoring the charging current based on the potential difference, a constant current reference power source serving as a reference for charging current adjustment during constant current charging, a battery voltage and a charging voltage A voltage monitoring circuit for monitoring the charge voltage, a constant voltage reference power source serving as a reference for charge voltage adjustment during constant voltage charging, a constant current constant voltage charging circuit for performing two types of charge control, constant current charging and constant voltage charging, A charger for monitoring a supply voltage on a charger side in a constant current and constant voltage charging system charging circuit including an FET for adjusting a charging current and a charging voltage and a charging control circuit for controlling all of the above charging circuits. A constant current reference D / A converter with a variable voltage value is provided as a constant current reference power supply, and the voltage of the constant current reference power supply is controlled when the supply voltage on the charger side drops. To do.

  Specifically, the supply voltage on the charger side during constant current charging is monitored by the charger voltage monitoring circuit, and when the supply voltage on the charger side reaches a threshold value or less, the charging current is measured by the charging current monitoring circuit. Based on the result, the voltage of the constant current reference D / A converter is adjusted so as to be a charging current suitable for the charger, and constant current saving charging is executed. Thereby, even if it is a case where a battery is charged using the charger with low charging current supply capability other than a regular charger, it becomes possible to charge a battery reliably. In addition, by generating an interrupt signal to the CPU when the supply voltage on the charger side falls below the threshold value, it is confirmed that the charger being used is not a regular charger or that the charger is abnormal. It is possible to notify the user.

  In order to describe the above-described embodiment of the present invention in more detail, a charging circuit and a charging control method according to a first example of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a configuration of a charging circuit incorporated in a mobile phone or the like, and FIG. 2 is a flowchart showing a charging procedure using the charging circuit of this embodiment. FIG. 3 is a diagram showing charger voltage, charging current, and battery voltage in each state from preliminary charging to constant voltage charging.

  As shown in FIG. 1, the charging circuit of the present embodiment includes a battery 1 serving as a power source for a mobile phone, a connector 4 to which a charger (not shown) is connected, and charging for detecting that the charger is connected. Generated by the charger detection circuit 6, the charger voltage monitoring circuit 5 for monitoring the supply voltage level from the charger, the charging current detection resistor 3 for generating a potential difference by the charging current, and the charging current detection resistor 3 A charging current monitoring circuit 7 that monitors the charging current according to a potential difference, and a constant current reference D / A converter 10 that is variable in voltage value and serves as a reference for charging current adjustment in constant current charging, preliminary charging, and constant current saving charging; The voltage monitoring circuit 8 that monitors the voltage and charging voltage of the battery 1, the constant voltage reference power source 11 that serves as a reference for adjusting the charging voltage during constant voltage charging, and the monitoring results and constant current reference in the charging current monitoring circuit 7 D / A converter Constant current constant voltage for performing two types of charge control: constant current charge for controlling the charge current according to the voltage value of the battery 10 and monitoring result of the voltage monitoring circuit 8 and constant voltage charge for controlling the charge voltage by the reference voltage reference power supply 11 Charging circuit 9, FET 2 for adjusting charging current and charging voltage, voltage switching of constant current reference D / A converter 10 and charging for controlling all of the charging circuit including constant current constant voltage charging circuit 9 The control circuit 12 includes a CPU 13 that controls functions of the mobile phone and determines the state of the mobile phone, receives an interrupt signal from the charge control circuit 12, and performs basic operations of the mobile phone.

  The operation of the charging circuit having the above configuration will be described with reference to the flowchart of FIG.

  First, when a charger is connected to the connector 4, the charger detection circuit 5 detects the connection of the charger in step S101. In step S102, under the control of the charging control circuit 12, the voltage value of the constant current reference D / A converter 10 is changed to the voltage value for preliminary charging, and preliminary charging is started.

  Next, in step S103, it is determined whether the voltage value monitored by the voltage monitoring circuit 8 is a threshold level for shifting to constant current charging. If the voltage value does not exceed the threshold level, preliminary charging is maintained, and the threshold level is exceeded. When the voltage reaches the constant current charging, the charging control circuit 12 changes the voltage value of the constant current reference D / A converter 10 to the voltage value for constant current charging and shifts to constant current charging.

  Here, in the conventional charging circuit, it is determined whether the voltage value of the battery 1 monitored by the voltage monitoring circuit during constant current charging is a threshold level for transition to constant voltage charging. However, in this control method, when the supply voltage on the charger side decreases and falls below the chargeable voltage, the charging is stopped, and when charging is stopped and the supply voltage on the charger side increases. In addition, since constant current charging is started, charging is repeatedly started / stopped.

  Therefore, in this embodiment, in step S105, the charging voltage monitoring circuit 15 monitors the supply voltage level from the charger during constant current charging, and compares the supply voltage on the charger side with a predetermined threshold level. Processing according to the comparison result is performed.

  Specifically, if the supply voltage on the charger side is not less than or equal to the threshold level, the threshold value at which the voltage value of the battery 1 monitored by the voltage monitoring circuit 8 shifts to constant voltage charging in step S106 as in the conventional case. If the level is equal to or higher than the threshold level for transition to constant voltage charging, the constant current constant voltage charging circuit 9 performs constant voltage charging in step S107, and performs a charging operation until charging is completed (S108, S109).

  On the other hand, if the supply voltage on the charger side in the charging voltage monitoring circuit 5 has reached the threshold level or lower during constant current charging in step S105, an interrupt signal is generated for the CPU 13 in step S110 and used. After notifying the user by displaying on the display means that the charger being charged is not a regular charger or that the charger is abnormal, in step S111, the potential difference of the charging current detection resistor 3 is also displayed. In step S112, the charging control circuit 12 changes the voltage value of the constant current reference D / A converter 10 to a voltage value suitable for the measured charging current, and in step S113, the charger Perform a constant current save charge with a suitable charge current. In step S114, the supply voltage level from the charger is monitored by the charge voltage monitoring circuit 15 during constant current save charging. When the supply voltage exceeds the threshold level, a normal charging operation is performed (S106 to S109).

  FIG. 3 shows the charger voltage, charging current, and battery voltage in each state from preliminary charging to constant voltage charging. During constant current charging, the charger voltage falls below the threshold level for transition to constant current save charging. If the charger voltage becomes equal to or higher than the return threshold level from the constant current save charge during the constant current save charge, it can be seen that the constant voltage save charge is entered.

  As described above, the charging circuit for the constant current and constant voltage charging system is provided with the charger voltage monitoring circuit 5 for monitoring the supply voltage on the charger side, and the constant current reference D for which the voltage value can be varied as the constant current reference power supply. / A converter 10 is used to monitor the supply voltage on the charger side during constant current charging with the charger voltage monitoring circuit 5, and when the supply voltage on the charger side falls below the threshold value, charging is performed with the charging current monitoring circuit 7 Based on the result of the current measurement, the voltage of the constant current reference D / A converter 10 is adjusted to a charging current suitable for the charger and the constant current saving charging is executed. Repeatedly, the problem that the battery is not charged can be avoided. In addition, when the supply voltage on the charger side reaches a threshold value or less, an interrupt signal is generated for the CPU 13 to confirm that the charger being used is not a regular charger or that the charger is abnormal. The user can also be notified.

  Next, a charging circuit and a charging control method according to the second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a block diagram showing the configuration of the charging circuit of the present embodiment.

  In the first embodiment described above, when switching the charging current during constant current charging, a drop in the supply voltage on the charger side is detected and the charging current is measured to adjust the voltage of the D / A converter. 4, instead of the constant current reference D / A converter 10, a constant current reference power supply 10 a and a constant current saving reference power supply 10 b are provided, and a decrease in supply voltage on the charger side is detected. The constant current saving reference power supply 10b may be switched to perform a constant current saving charging.

  In this configuration, the constant current saving charge control is simplified, and the battery can be charged without stopping the charge even when charging with a charger having a low charging current supply capability.

  The circuit configurations in FIGS. 1 and 4 are examples, and the supply voltage on the charger side is monitored, and the voltage value of the constant current reference power supply is charged when the supply voltage on the charger side reaches a threshold value or less. Any charging circuit capable of performing constant current saving charging by adjusting to a voltage value suitable for the current can be used.

  The charging circuit and the charging control method of the present invention can be applied not only to a mobile phone but also to any device that performs charging using a constant current constant voltage charging method.

It is a block diagram which shows the structure of the charging circuit which concerns on 1st Example of this invention. It is a flowchart which shows the procedure of charge using the charging circuit which concerns on 1st Example of this invention. It is a figure which shows the change of the charger voltage, charging current, and battery voltage in each state of preliminary charge, constant current charge, constant current save charge, and constant voltage charge. It is a block diagram which shows the structure of the charging circuit which concerns on the 2nd Example of this invention. It is a block diagram which shows the structure of the conventional charging circuit. It is a flowchart which shows the procedure of the charge using the conventional charging circuit.

Explanation of symbols

1 Battery 2 Charge control FET
DESCRIPTION OF SYMBOLS 3 Charge current detection resistor 4 Connector 5 Charger voltage monitoring circuit 6 Charger detection circuit 7 Charging current monitoring circuit 8 Voltage monitoring circuit 9 Constant current constant voltage charging circuit 10 D / A converter for constant current reference 10a Reference power supply for constant current 10b constant current save reference power supply 11 constant voltage reference power supply 12 charge control circuit 13 CPU
101 battery 102 charge control FET
DESCRIPTION OF SYMBOLS 103 Charging current detection resistor 104 Connector 106 Charger detection circuit 107 Charging current monitoring circuit 108 Voltage monitoring circuit 109 Constant current constant voltage charging circuit 110 Constant current reference power supply 111 Constant voltage reference power supply 112 Charge control circuit

Claims (10)

In a charging circuit that charges a battery by a constant current constant voltage charging method,
A charging circuit characterized in that the charging current during constant current charging can be switched according to the supply voltage of the charger. In a charging circuit that charges a battery by a constant current constant voltage charging method,
Means for comparing the supply voltage of the charger with a predetermined threshold during constant current charging;
When the supply voltage of the charger becomes equal to or lower than the threshold value, the charging current of the constant current charging is switched from the first charging current to the second charging current set according to the performance of the charger. And a charging circuit. A charger detection circuit for detecting a charger, a charging current monitoring circuit for monitoring a charging current, a voltage monitoring circuit for monitoring a battery voltage and a charging voltage, a constant current reference power source serving as a power source during constant current charging, Constant voltage reference power source for constant voltage charging, constant current constant voltage charging circuit for charging with constant current or constant voltage, FET for adjusting charging current and charging voltage, and charge switching control In a constant current constant voltage charging system charging circuit comprising at least a charge control circuit for performing
A charger voltage monitoring circuit for monitoring a supply voltage of the charger;
The constant current reference power source is switchable between a first charging current and a second charging current set according to the performance of the charger,
In the charger voltage monitoring circuit, when the supply voltage of the charger is equal to or lower than the threshold value as a result of comparing the supply voltage of the charger with a predetermined threshold value, the charging control means performs constant current charging. The charging circuit is switched from the first charging current to the second charging current.   4. The charging circuit according to claim 3, wherein the constant current reference power source is a D / A converter.   5. The charging circuit according to claim 2, wherein the CPU generates an interrupt signal when a supply voltage of the charger becomes equal to or lower than the threshold value. 6. A charge control method using a charging circuit for charging a battery by a constant current constant voltage charging method,
A charge control method characterized by performing control to switch a charge current during constant current charging according to a supply voltage of a charger. A charge control method using a charging circuit for charging a battery by a constant current constant voltage charging method,
When the supply voltage of the charger becomes equal to or lower than a predetermined threshold during constant current charging, the charging current for the constant current charging is set according to the performance of the charger from the first charging current. The charge control method characterized by performing control which switches to 2 charge currents. A charge control method using a charging circuit for charging a battery by a constant current constant voltage charging method,
Charging with a first charging current;
Measuring the supply voltage of the charger and comparing the supply voltage of the charger with a predetermined threshold;
When the supply voltage of the charger becomes equal to or lower than the threshold, the charging current for constant current charging is switched from the first charging current to a second charging current set according to the performance of the charger. Steps,
Measuring a battery voltage and comparing the battery voltage with another predetermined threshold;
And a step of switching to constant voltage charging when the battery voltage becomes equal to or higher than the other threshold value.   9. The charging control method according to claim 8, wherein a D / A converter is used as a constant current reference power source during constant current charging.   10. The charge control method according to claim 7, wherein when the supply voltage of the charger becomes equal to or lower than the threshold, the CPU generates an interrupt signal. 11.

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