TWI411195B - Charging circuit of handheld device and related controlling circuit - Google Patents

Abstract

A charging circuit of a handheld device utilizes a current adjusting circuit to receive and provide current supplied by an outer power source to a battery of the handheld device, utilizes a detecting circuit to detect the charging state of the battery, utilizes a charging control circuit to adjust the current provided to the battery according to the detecting result of the detecting circuit, utilizes a voltage limiting circuit to limit the voltage the outer power source input to the charging control circuit, and utilizes a current limiting circuit to limit the current flowing through the voltage limiting circuit. The voltage limiting circuit and the charging control circuit can both be fabricated by the normal process instead of the high-voltage process; thereby the production cost and complexity of the handheld device can be decreased.

Description

Handheld device charging circuit and related control circuit

The present invention relates to a charging circuit for a handheld device, and more particularly to a charging circuit that can eliminate high voltage voltage stabilizing components.

Handheld devices (such as cell phones) need to have a voltage limiting function to prevent the unstable charger from generating excessive voltage damage to the internal control chip of the handheld device, for example, when the user mistakenly uses different specifications of the charger for the handheld device. When charging, if the voltage supplied by the charger is higher than the operating voltage of the control chip, and the handheld device does not limit the voltage received, the control chip is easily burned. The general solution is to externally connect a high voltage regulator to the control wafer, or use a special high voltage process to design the control wafer so that the control wafer can withstand high voltages. However, whether the cost of a high voltage regulator or a high voltage process is not low, the production cost of the handheld device is increased.

In view of the above, one of the objects of the present invention is to provide a charging circuit for a handheld device that uses a normal pressing component to protect the control chip of the handheld device from being damaged by an excessive charging voltage, thereby eliminating high voltage. Regulator components or high-voltage processes reduce the cost and complexity of handheld devices.

According to an embodiment of the invention, a charging circuit for a handheld device is provided. The charging circuit is configured to provide a current supplied by an external power source for charging a battery of the handheld device, the charging circuit further comprising a current regulating circuit, a sensing circuit, a charging control circuit, and a voltage limiting piezoelectric Road and a current limiting circuit. The current regulating circuit is configured to receive the current supplied by the external power source and adjust the current to charge the battery, the sensing circuit senses the state of charge of the battery to generate a sensing result, and the charging control circuit is based on the sensing result A current regulation signal is generated, the voltage limiting circuit limits the voltage value input to the charging control circuit, and the current limiting circuit limits the current value input to the voltage limiting component.

According to an embodiment of the invention, a control circuit for a charging circuit of a handheld device is disclosed. The control circuit is configured to control a current regulating circuit to adjust a current for charging the battery according to a voltage of an external power source and a charging state of the battery of the handheld device, the control circuit further comprising an overvoltage protection circuit and a charging control The circuit and a voltage limiting circuit, the overvoltage protection circuit determines whether to generate an overvoltage protection signal according to the detection value, and the charging control circuit generates a current adjustment signal according to the charging state of the battery and the overvoltage protection signal. The voltage limiting circuit limits the voltage value input to the charging control circuit.

Please refer to FIG. 1, which is a schematic diagram of an embodiment of a charging circuit of the present invention. The charging circuit 100 includes a current regulating circuit 110, a sensing circuit 120, a charging control circuit 130, a voltage limiting circuit 140, a current limiting circuit 150, and a charging port 170. The charging circuit 100 can be applied to a handheld device, such as a cell phone, a personal digital assistant (PDA), to provide a charging management function. When the charger (not shown) of the handheld device is inserted into the charging device 170, the battery 180 of the handheld device is charged through the charging path formed by the charging device 170, the current regulating circuit 110 and the sensing circuit 120. The sensing circuit 120 can detect the charging state of the battery 180 by sensing the voltage value of the battery 180 or sensing the current value on the charging path, and feedback the sensing result to a driving circuit of the charging control circuit 130. 135. The current adjustment circuit 110 is further controlled by the driving circuit 135 according to the sensing result to adjust the magnitude of the current supplied to the battery 180. In one embodiment, the sensing circuit 120 includes a resistor, the current regulating circuit 110 includes a transistor, and the driving circuit 135 is based on a terminal voltage of the resistor (which corresponds to the voltage value of the battery 180) or a resistor. The voltage across the voltage (which corresponds to the current value on the charging path) controls the degree of switching of the transistor to control the amount of current provided by the charger to the battery 180.

The charge control circuit 130 also accepts power from the charger. As described in the prior art, an excessive voltage generated by an unstable charger may damage the charge control circuit 130, such as a user accidentally using a charger of a different specification. The charging port 170 is inserted, and the voltage supplied by the charger is higher than the operating voltage of the charging control circuit 130. In order to prevent the charging control circuit 130 from being affected by the above, the voltage limiting circuit 140 is used to limit the voltage value Vc of the charger input charging control circuit 130, and the current limiting circuit 150 is used to limit the flow to the voltage limiting circuit. The current value of 140 is Ir.

Please refer to FIG. 2, which shows an embodiment of the voltage limiting circuit 140 and the current limiting circuit 150. The voltage limiting circuit 140 can be a Zener diode or a shunt regulator. Or other active or passive clamp elements are implemented, and the current limiting circuit 150 is a passive component, such as the illustrated resistor, in this embodiment. When the voltage Vin supplied by the charger is lower than the clamp voltage of the voltage limiting circuit 140, as shown in FIG. 3, the current Ir flowing through the voltage limiting circuit 140 is almost zero, and the voltage limit is The voltage circuit 140 hardly operates. At this time, the voltage Vc input to the charging control circuit 130 is approximately equal to the input voltage Vin; however, when the voltage Vin supplied by the charger is higher than the clamp voltage value Vp of the voltage limiting circuit 140. The voltage limiting circuit 140 is turned on, and the current amount Ir flowing through the voltage limiting circuit 140 is increased, so that the current Ic flowing to the charging control circuit 130 is maintained at a constant value. At this time, the current limiting circuit 150 has a voltage drop across the input circuit 150 to make an input. The voltage Vc of the charging control circuit 130 is maintained at the clamp voltage value Vp of the voltage limiting circuit 140. The voltage Vc provides the charging control circuit 130 for normal operation. If the clamping voltage value Vp is exceeded, the charging control circuit 130 may be caused. The voltage is burned. The current limiting circuit 150 provides a current limiting function, so that the current Ir does not rise sharply, and the voltage limiting circuit 140 can limit the voltage Vc to its clamping voltage value Vp without injecting a large amount of current Ir, so that the charging control The circuit 130 does not operate normally due to the input voltage Vin.

4 is a schematic diagram of another embodiment of voltage limiting circuit 140 and current limiting circuit 150. In this embodiment, the current limiting circuit 150 further includes an active component, such as the illustrated transistor. When the voltage Vc exceeds the clamp voltage value Vp (the current Ic does not change, the current Ir increases), the voltage limiting circuit 140 The base voltage of the transistor in the current limiting circuit 150 is lowered, so that the voltage passing through the transistor and the collector current are lowered, so that the voltage Vc is lowered and does not exceed the clamp voltage value Vp. The above design can also prevent the voltage Vc from exceeding the clamp voltage value Vp, so that the charge control circuit 130 does not operate normally due to the input voltage Vin.

The clamp voltage value of the voltage limiting circuit 140 is designed according to the operable voltage range or the highest withstand voltage value of the charging control circuit 130, thus ensuring that the charging control circuit 130 is not damaged by the overvoltage of the charger. In one embodiment, the charge control circuit 130 and the voltage limiting circuit 140 are integrated in the wafer 190 of the handheld device, and the voltage limiting circuit 140 controls the voltage Vc to be operable on the low voltage/normal pressure component. In the voltage range, for example, the design clamp voltage value is 6V, the wafer 190 can also have the function of high voltage protection without using a special high voltage process.

The charging circuit 100 further includes a high voltage blocking circuit 160 coupled between the current regulating circuit 110, the current limiting circuit 150, and the driving circuit 135. In an embodiment, the high voltage blocking circuit 160 includes an NMOS transistor. The gate terminal is coupled to the current limiting circuit 150, the source terminal is coupled to the current regulating circuit 110, and the drain terminal is coupled to the driving circuit 135. Therefore, the gate voltage of the NMOS transistor can be controlled by the gate voltage. Therefore, when the voltage Vin provided by the charger is too high, the high voltage blocking circuit 160 can isolate the input voltage Vin and the driving circuit 135 to prevent the driving circuit 135 from being burnt due to the overvoltage to ensure that the driving circuit 135 can still operate normally.

In addition, as shown in FIG. 5, the charging circuit 100 further includes a voltage detecting circuit 210 and an over voltage protection (OVP) circuit 220, wherein the voltage detecting circuit 210 is used to detect the charger. The voltage value Vin is output to generate a detection value, and the overvoltage protection circuit 220 determines whether to activate the overvoltage protection function according to the detection value, and notifies the driving circuit 135 to turn off the current adjustment circuit 110 to stop charging the battery 180. In one embodiment, the voltage detecting circuit 210 is a voltage divider for detecting the voltage Vin and providing a voltage limiting protection to the interface of the wafer 190, and the voltage dividing coefficient can be determined according to the wafer 190. The operating voltage is designed, for example, when the voltage dividing coefficient is 4, and the maximum voltage supplied by the charger is 24V, the maximum voltage of the input overvoltage protection circuit 220 after being divided is 6V, and does not exceed the wafer 190. Withstand voltage range.

The detected value of the voltage detecting circuit 210 is then input to the overvoltage protection circuit 220. The overvoltage protection circuit 220 compares the detected value with a reference value to determine whether to activate the overvoltage protection function, and the reference value is based on the current regulating circuit 110. Set by operating power. In an embodiment, when the overvoltage protection circuit 220 determines that the voltage Vin of the charger is higher than the reference value, in order to avoid overheating damage to the components on the charging path, the driving circuit 135 completely turns off the current regulating circuit 110, so that the current flows. The amount of current of the regulating circuit 110 is zero. Otherwise, since the voltage Vin is high, if a slight current flows, a considerable power consumption is generated on the current regulating circuit 110, causing the current regulating circuit 110 to burn out.

As shown, the charge control circuit 130, the voltage limiting circuit 140, and the overvoltage protection circuit 220 can be integrated into the wafer 190 of the handheld device and fabricated from the same atmospheric semiconductor process, such as standard complementary metal oxide. The semiconductor (CMOS) process, in this way, the chip 190 can withstand the overvoltage of the charger without external high voltage regulator or special high voltage process, which can reduce the production cost of the handheld device.

Next, the operation of the voltage limiting circuit 140 and the overvoltage protection circuit 220 will be described using FIG. 6 as an example. When the charger is inserted into the charging port 170, if the voltage Vin provided by the charger is maintained at the normal operating voltage V _nomal , for example 5V, the voltage limiting circuit 140 and the overvoltage protection circuit 220 do not operate, and the charging control circuit 130 senses The sensing result of the measurement circuit 120 adjusts the degree of switching of the current adjustment circuit 110 to cause the battery 180 to be stably charged until the battery 180 reaches the saturation state. When the voltage Vin of the charger is unstable, higher than the clamp voltage Vp (for example, 6V), the voltage limiting circuit 140 clamps the voltage value Vc of the input charging control circuit 130 to 6V, and the voltage difference of (Vin-Vp) Then across the current limiting circuit 150, the charging control circuit 130 can operate within the normal operating voltage range, at which time the overvoltage protection circuit 220 still does not operate. When the voltage Vin of the charger continues to rise and is higher than the overvoltage protection point V _ovp , the over voltage protection circuit 220 activates the over voltage protection function, and the control driving circuit 130 turns off the current adjustment circuit 110 and stops charging the battery 180 . To protect the components on the charging path from damage due to overheating.

The charging circuit 100 utilizes a voltage limiting component (for example, a shunt regulator) in a handheld device to implement overvoltage protection, and the voltage limiting circuit 140, the charging control circuit 130, and the overvoltage protection circuit 220 can be used. In order to continuously press the component, the wafer 190 can be used in a normal pressing process, which helps to reduce the production cost and complexity of the handheld device.

The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

100‧‧‧Charging circuit

110‧‧‧ Current Regulation Circuit

120‧‧‧Sensor circuit

130‧‧‧Charging control circuit

135‧‧‧ drive circuit

140‧‧‧Voltage voltage limiting circuit

150‧‧‧ Current limiting circuit

160‧‧‧High voltage blocking circuit

170‧‧‧Charging equipment

180‧‧‧Battery

190‧‧‧ wafer

210‧‧‧Voltage detection circuit

220‧‧‧Overvoltage protection circuit

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic illustration of one embodiment of a charging circuit of the present invention.

Fig. 2 is a schematic view showing an embodiment of a voltage limiting circuit and a current limiting circuit in Fig. 1.

Fig. 3 is a schematic diagram showing the voltage limiting circuit of Fig. 1 controlling the voltage Vc input to the charging control circuit of the charger to the clamp voltage Vp.

Fig. 4 is a schematic view showing another embodiment of the voltage limiting circuit and the current limiting circuit of Fig. 1.

Figure 5 is a schematic illustration of another embodiment of a charging circuit of the present invention.

Figure 6 is a schematic diagram of the operation of the voltage limiting circuit and the overvoltage protection circuit of Figure 5.

100. . . Charging circuit

110. . . Current regulation circuit

120. . . Sense circuit

130. . . Charging control circuit

135. . . Drive circuit

140. . . Voltage limiting circuit

150. . . Current limiting circuit

160. . . High voltage blocking circuit

170. . . Charging

180. . . battery

190. . . Wafer

Claims (8)

A charging circuit for a handheld device for receiving a current supplied by an external power source for charging a battery of the handheld device, the charging circuit comprising: a current regulating circuit coupled to the external power source and the a battery for receiving a current supplied by the external power source and adjusting the current to charge the battery; a sensing circuit coupled to the battery for sensing a state of charge of the battery to generate a sensing result; a charging control circuit coupled to the sensing circuit and the current regulating circuit for generating a current adjustment signal according to the sensing result; a voltage limiting circuit coupled to the charging control circuit for limiting Inputting a voltage value of the charging control circuit to protect the charging control circuit; and a current limiting circuit coupled to the voltage limiting circuit and the external power source for limiting a current value input to the voltage limiting circuit, To protect the charging control circuit; wherein the current regulating circuit adjusts the current to charge the battery according to the current adjustment signal. The charging circuit of claim 1, further comprising: a voltage detecting circuit coupled to the external power source for detecting an output voltage value of the external power source to generate a detected value; and a The overvoltage protection circuit is coupled to the voltage detection circuit and the charging control circuit for determining whether to generate an overvoltage protection signal according to the detection value; wherein the charging control circuit starts the overvoltage according to the overvoltage protection signal Protection work can. The charging voltage according to claim 2, wherein the overvoltage protection circuit compares the detected value with a reference value to determine whether an overvoltage protection signal is generated, and the reference value is based on the current regulating circuit. Set by operating voltage range. The charging circuit of claim 1, wherein the voltage limiting circuit and the charging control circuit are integrated in the same integrated circuit and are fabricated by a standard complementary metal oxide semiconductor (CMOS) process. The charging circuit of claim 1, wherein the current limiting circuit comprises a passive component. The charging circuit of claim 1, wherein the current limiting circuit comprises an active component. A control circuit for a charging circuit of a handheld device is configured to adjust a current for charging a battery according to a voltage of an external power source and a state of charge of a battery of the handheld device, the control circuit comprising: an overvoltage protection circuit And being coupled to the external power source for determining whether to generate an overvoltage protection signal according to the detected value; a current regulating circuit coupled to the external power source and the battery for receiving the current supplied by the external power source And adjusting the current to charge the battery; a sensing circuit coupled to the battery for sensing a state of charge of the battery to generate a sensing result; a charging control circuit coupled to the sensing circuit, the current regulating circuit, and the overvoltage protection circuit And generating a current adjustment signal according to the sensing result and the overvoltage protection signal; a voltage limiting circuit coupled to the charging control circuit for limiting a voltage value input to the charging control circuit to protect The current control circuit is coupled to the voltage limiting circuit and the external power source for limiting a current value input to the voltage limiting circuit to protect the charging control circuit; and a high voltage blocking a circuit coupled to the current limiting circuit, the charging control circuit, and the current regulating circuit for isolating the charging control circuit and the current regulating circuit to prevent an input voltage from entering the electrical control circuit; wherein the current regulating circuit is configured according to the current The current adjustment signal is adjusted to charge the battery. The charging circuit of claim 1, wherein the overvoltage protection circuit, the charging control circuit and the voltage limiting circuit are integrated in a same integrated circuit and are in a standard complementary metal oxide semiconductor (CMOS) process. Made.