CN208754025U

CN208754025U - A kind of switched charge circuit

Info

Publication number: CN208754025U
Application number: CN201821359751.2U
Authority: CN
Inventors: 程剑涛; 黄建刚; 王云松; 吴传奎
Original assignee: Shanghai Awinic Technology Co Ltd
Current assignee: Shanghai Awinic Technology Co Ltd
Priority date: 2018-08-22
Filing date: 2018-08-22
Publication date: 2019-04-16
Anticipated expiration: 2028-08-22

Abstract

The utility model discloses a kind of switched charge circuits, the operating voltage of the switched charge circuit is less than preset voltage value, comprising: first switch tube, second switch, third switching tube, inductance, first capacitor, the second capacitor, driving circuit, electric power selection apparatus and control circuit；Wherein, the electric power selection apparatus selects the voltage value of the second end of the first switch tube and the larger value of the voltage value in the voltage output end to export to the driving circuit；The control circuit controls the first switch tube work in the first operating mode under the first preset condition, the first switch tube work is controlled under the second preset condition in the second operating mode, wherein, in this first operative mode, the first switch tube work is in saturation region；In the second mode of operation, the first switch tube work is in linear amplification region.Switched charge circuit cost provided by the utility model is lower, and the supply voltage provided for building blocks such as its driving circuits is more stable.

Description

Switch charging circuit

Technical Field

The utility model relates to a battery charging technology field especially relates to a switch charging circuit.

Background

With the development of electronic technology, more and more portable electronic devices are in use, so that the life of people is more convenient and more colorful. The lithium ion battery has the characteristic of being capable of being charged repeatedly, and gradually becomes a power supply of the portable electronic equipment, so that the charging chip for charging the lithium ion battery has a wide application market.

The existing charging technology is divided into linear charging and switch charging, and the efficiency of the switch charging is higher. Therefore, it is an urgent technical problem to be solved by those skilled in the art to provide a switching charging circuit with low cost and stable supply voltage.

SUMMERY OF THE UTILITY MODEL

In order to solve the above technical problem, an embodiment of the utility model provides a switch charging circuit, this switch charging circuit cost is lower, and can provide comparatively stable supply voltage.

In order to solve the above problems, the embodiment of the utility model provides a following technical scheme:

a switch charging circuit is used for charging a lithium ion battery, the working voltage of the switch charging circuit is less than a preset voltage value, and the charging circuit comprises: the circuit comprises a first switching tube, a second switching tube, a third switching tube, an inductor, a first capacitor, a second capacitor, a driving circuit, a power selector and a control circuit; wherein,

the control end of the first switching tube is electrically connected with the control circuit, the first end of the first switching tube is electrically connected with the power supply voltage end, and the second end of the first switching tube is grounded through a first capacitor;

the control end of the second switching tube is electrically connected with the driving circuit, the first end of the second switching tube is electrically connected with the second end of the first switching tube, and the second end of the second switching tube is electrically connected with the first end of the third switching tube;

the control end of the third switching tube is electrically connected with the driving circuit, the first end of the third switching tube is electrically connected with the second end of the second switching tube, and the second end of the third switching tube is grounded;

the first end of the inductor is electrically connected with the second end of the second switching tube, and the second end of the inductor is electrically connected with the first end of the second capacitor;

the first end of the second capacitor is electrically connected with the second end of the inductor, the second end of the second capacitor is grounded, and the first end of the second capacitor is used as a voltage output end to charge the lithium ion battery;

the first input end of the power supply selector is electrically connected with the second end of the first switch tube, the second input end of the power supply selector is electrically connected with the voltage output end, the output end of the power supply selector is electrically connected with the driving circuit, and the larger value of the voltage value of the second end of the first switch tube and the voltage value of the voltage output end is selected to be output to the driving circuit;

the control circuit controls the first switching tube to work in a first working mode under a first preset condition, and controls the first switching tube to work in a second working mode under a second preset condition, wherein the first switching tube works in a saturation region under the first working mode; in the second working mode, the first switching tube works in a linear amplification area.

Optionally, the first preset condition includes: the switch charging circuit is in a power-on stage; the second preset condition includes: the switch charging circuit is in a stable working state.

Optionally, the control circuit includes:

a first voltage branch, the first voltage branch comprising: the input end of the amplifying circuit is electrically connected with the power supply voltage end, and the output end of the amplifying circuit is electrically connected with the control end of the first switching tube;

a second voltage branch, the second voltage branch comprising: the first end of the first Zener diode is electrically connected with the first end of the control switch, the second end of the first Zener diode is electrically connected with the control end of the first switching tube, the control end of the control switch is electrically connected with the control chip, and the second end of the control switch is grounded;

the control chip controls the control switch to be switched on under the first preset condition, and controls the control switch to be switched off under the second preset condition.

Optionally, the switch charging circuit further includes: the band-gap reference circuit is electrically connected with the input end of the control chip and the output end of the power supply selector, wherein the output end of the power supply selector provides working voltage for the band-gap reference circuit; the band-gap reference circuit is used for detecting the power-on state of the switch charging circuit, and outputting a first control instruction when the power-on of the switch charging circuit is completed; and the control chip responds to the first control instruction and controls the control switch to be switched off.

Optionally, the first voltage branch further includes: a first resistor between the supply voltage terminal and the amplification circuit.

Optionally, the first voltage branch further includes: and one end of the second Zener diode is electrically connected with the first resistor and the common end of the amplifying circuit, and the other end of the second Zener diode is grounded.

Optionally, the amplifying circuit is a charge pump.

Optionally, the first preset condition further includes: the switch charging circuit generates an abnormal event.

Optionally, the switch charging circuit further includes: the protection circuit is electrically connected with the input end of the control chip and the output end of the power supply selector, the output end of the power supply selector provides working voltage for the protection circuit, the protection circuit is used for monitoring the working state of the switch charging circuit, when the working state of the switch charging circuit generates an abnormal event, a second control instruction is output, and the control chip responds to the second control instruction and controls the control switch to be closed.

Optionally, the method further includes: a sampling resistor between the inductor and the second capacitor; the sampling circuit is used for acquiring signals on the sampling resistor; the driving circuit also adjusts the duty ratio of the second switching tube and/or the third switching tube based on the control instruction output by the sampling circuit so as to maintain the voltage of the voltage output end of the switch charging circuit stable.

Compared with the prior art, the technical scheme has the following advantages:

in the technical solution provided in the embodiment of the present invention, when the switch charging circuit is in the first preset condition, the control circuit controls the first switch tube to operate in the saturation region, so that the first power supply voltage is controlled by the control end voltage of the first switch tube, and the control circuit can control the voltage of the control end of the first switch tube, so that the first power supply voltage is in the low voltage state; when switch charging circuit is in the second and predetermines the condition, control circuit control first switch tube work is in linear amplification district, first supply voltage equals supply voltage end VBUS's magnitude of voltage subtracts the voltage drop on the first switch tube, and the embodiment of the utility model provides a switch charging circuit is low voltage switch charging circuit, just the second predetermines the condition and does switch charging circuit is in stable operation state, consequently, this moment the voltage of supply voltage end input also is low-voltage, thereby makes first supply voltage also is low-voltage.

Therefore, in the switch charging circuit provided by the embodiment of the present invention, the second end of the first switch tube is always kept low voltage and powered, and therefore, the second end of the first switch tube is used as an input voltage of the power selector, so that the first power supply voltage input by the power selector is always low voltage and powered, and therefore, the subsequent second switch tube and the subsequent third switch tube can both adopt low voltage power tubes, so as to reduce the cost of the switch charging circuit.

Furthermore, the embodiment of the utility model provides an among the switch charging circuit, because node PMID's voltage remains the low-voltage throughout, can not because of drive circuit needs hundreds of milliamperes rank current peak and great floating appears when driving second switch tube and third switch tube switch, thereby makes the utility model provides an among the switch charging circuit who provides, first supply voltage is comparatively stable, has solved among the prior art because of drive circuit needs hundreds of milliamperes rank current peak when driving second switch tube and third switch tube switch, and leads to power supply Vmax appears unstable phenomenon, causes the unusual problem of switch charging circuit work.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic circuit diagram of a charging chip of a lithium ion battery in the prior art;

fig. 2 is a schematic circuit diagram of another lithium ion battery charging chip in the prior art;

fig. 3 is a schematic circuit diagram of another lithium ion battery charging chip in the prior art;

fig. 4 is a schematic circuit diagram of a switch charging circuit according to an embodiment of the present invention;

fig. 5 is a schematic circuit diagram of a switch charging circuit according to another embodiment of the present invention;

fig. 6 is a schematic circuit diagram of a switch charging circuit according to another embodiment of the present invention;

fig. 7 is a schematic circuit diagram of a switch charging circuit according to still another embodiment of the present invention;

fig. 8 is a schematic circuit diagram of a switch charging circuit according to another embodiment of the present invention;

fig. 9 is a timing signal diagram of a switch charging circuit according to an embodiment of the present invention;

fig. 10 is a schematic diagram of a partial circuit structure of a switch charging circuit under a first preset condition according to an embodiment of the present invention;

fig. 11 is a schematic diagram of a partial circuit structure of a switch charging circuit under a second preset condition according to an embodiment of the present invention;

fig. 12 is a schematic circuit diagram of a switch charging circuit according to another embodiment of the present invention;

fig. 13 is a schematic circuit diagram of a charge pump according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be implemented in other ways different from the specific details set forth herein, and one skilled in the art may similarly generalize the present invention without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.

As shown in fig. 1, fig. 1 is a schematic diagram illustrating a circuit structure of a charging chip of a lithium ion battery in the prior art. As can be seen from fig. 1, the lithium ion battery charging chip includes:

a first switch tube M1 electrically connected to a supply voltage terminal VBUS, a control terminal of the first switch tube M1 being electrically connected to the charge pump, a first terminal being grounded via a first capacitor C1, and a second terminal being electrically connected to the supply voltage terminal VBUS, wherein a common terminal of the first switch tube M1 and the first capacitor C1 defines a node PMID;

a drive circuit;

a second switching tube M2 and a third switching tube M3 electrically connected to the driving circuit, wherein a control terminal of the second switching tube M2 is electrically connected to the driving circuit, a first terminal is electrically connected to a common terminal of the first switching tube M1 and the first capacitor C1, a second terminal is electrically connected to a first terminal of the third switching tube M3, a control terminal of the third switching tube is electrically connected to the driving circuit, and the second terminal is grounded;

a series branch electrically connected to a common terminal of the second switching tube M2 and the third switching tube M3, the series branch comprising an inductance L and a sampling resistance Rsns connected in series;

and the second capacitor C2 and the lithium ion battery are electrically connected with one side of the common end of the series branch, which is far away from the second switching tube M2 and the third switching tube M3, wherein one end of the second capacitor C2, which is far away from the series branch, is grounded.

Specifically, when the second switching tube M2 is turned on and the third switching tube M3 is turned off, the supply voltage terminal VBUS supplies power to the lithium ion battery through the first switching tube M1 and the second switching tube M2, charges the inductor L and the second capacitor C2, and stores charges by using the inductor and the second capacitor C2; when the second switching tube M2 is turned off and the third switching tube M3 is turned on, power is continuously supplied to the lithium ion battery by the inductor L and the second capacitor C2.

However, in the structure of the switch chip, the body diode formed by the first switch tube M1 points to the node PMID, and because the diode has a forward conduction characteristic, during the operation of the switch chip, a voltage difference between two ends of the first switch tube M1 (i.e., a voltage difference between the supply voltage end VBUS and the node PMID) does not exceed a conduction voltage drop of the body diode, so that when the supply voltage end VBUS is a high voltage, the node PMID electrically connected with the supply voltage end VBUS is also a high voltage, and further, the subsequent second switch tube M2 and the subsequent third switch tube M3 must be high-voltage power tubes to ensure the normal operation of the switch chip, which results in a higher cost of the switch chip.

As shown in fig. 2, fig. 2 is a schematic diagram of a circuit structure of another lithium ion battery charging chip. As can be seen from a comparison of fig. 1 and 2, the structure shown in fig. 2 differs from that of fig. 1 in that: in fig. 2, the first terminal of the first switch tube M1 is electrically connected to the supply voltage VBUS, and the second terminal is electrically connected to the node PMID, so that in the circuit structure shown in fig. 2, the body diode formed by the first switch tube M1 points to the supply voltage VBUS and deviates from the node PMID, because the diode has the characteristic of forward conduction, when the supply voltage VBUS is low voltage, the first switch tube M1 is controlled to be conducted by the charge pump, the node PMID is also low voltage, when the supply voltage VBUS is high voltage, the first switch tube M1 is controlled to be cut off by the charge pump, at this time, since the body diode in the first switch tube M1 is cut off in the reverse direction, the node PMID is also low voltage, that is, no matter whether the supply voltage VBUS is high voltage or low voltage, the node PMID in the switch chip is always maintained at low voltage, so that the subsequent second switch tube M2 and the second switch tube M3 can both adopt low-voltage power tubes, thereby reducing the cost of the switch chip.

As shown in fig. 3, fig. 3 is a schematic diagram of a circuit structure of a lithium ion battery charging chip. Compared with the circuit structure shown in fig. 2, the circuit structure shown in fig. 3 further includes:

a first resistor R1, one end of the first resistor R1 is electrically connected with the supply voltage end VBUS and the common end of the first switch tube M1, and the other end is grounded through a Zener diode D;

and a first input end of the power supply selector is electrically connected with a common end of the first resistor R1 and the Zener diode D, a second input end of the power supply selector is electrically connected with a common end of the second capacitor C2 and the battery, and an output end of the power supply selector is electrically connected with the driving circuit to provide working voltage for the driving circuit.

During specific work, after the power supply voltage end VBUS is powered on, a first power supply voltage Vcc is generated through a branch where the first resistor R1 and the Zener diode D are located, and the voltage value of the first power supply voltage Vcc is equal to the voltage value of the power supply voltage end VBUS, namely the voltage drop generated on the first resistor R1. Specifically, when the supply voltage terminal VBUS is a low voltage, the zener diode D is not broken down, and almost no current flows through the first resistor R1, so that no voltage drop occurs across the first resistor R1, and the voltage of the first supply voltage Vcc in a quiescent state is the voltage output by the supply voltage terminal VBUS; when the supply voltage terminal VBUS is a high voltage, the zener diode D is broken down, a current flows through the first resistor R1, a voltage drop is generated across the first resistor R1, and the zener diode D has a voltage stabilizing characteristic (i.e., after the zener diode is broken down, a voltage difference across the zener diode is stabilized at a voltage value, which is about 5.6V), so that the first supply voltage Vcc is clamped at a stable low voltage value by the zener diode. The power supply selector selects the larger value of the first power supply voltage Vcc and the second power supply voltage VBAT as the power supply Vmax. Specifically, when a voltage is input at the supply voltage end VBUS, the switch chip is in a charging state, the second supply voltage VBAT is small, and the power supply selector selects the first supply voltage Vcc as the supply power Vmax; when the supply voltage end VBUS end is suspended, the power supply selector selects the second supply voltage VBAT as the supply power Vmax to maintain the normal operation of the charging chip. The power supply Vmax is used for providing working voltage for components such as a driving circuit and a charge pump in the charging chip.

In addition, the charging chip may further include a bandgap reference circuit, a loop control circuit and/or a protection circuit, etc. electrically connected to the power supply Vmax.

It should be noted that, since the maximum value of the current that can be sustained by the zener diode in breakdown is limited, the first resistor R1 usually has a kiloohm level, so that when the voltage value of the supply voltage terminal VBUS is ensured to be high, and the zener diode is broken down, the current flowing through the zener diode is not too large, and the zener diode is burnt down.

It should be further noted that, when the driving circuit drives the second switch tube M2 and the third switch tube M3 to switch, a current spike of hundreds of milliamperes may be required, and therefore, when the power supply selector selects the first power supply voltage Vcc as the power supply Vmax of the driving circuit, if the second switch tube M2 and the third switch tube M3 generate a switching action, a current of hundreds of milliamperes may flow through the first resistor R1, so that a voltage drop larger than a stable operation state (i.e. a state where no switching operation is generated) of the second switch tube M2 and the third switch tube M3 is generated on the first resistor R1, which results in an unstable first power supply voltage, and thus the power supply Vmax is unstable, which affects the operation of the battery charging chip including the driving circuit, and in severe cases even results in an error of the switch chip control logic, with unpredictable consequences.

Therefore, it is an urgent technical problem to be solved by those skilled in the art to provide a switching charging circuit with low cost and stable supply voltage.

In view of this, an embodiment of the present invention provides a switch charging circuit, which is used for charging a lithium ion battery. It should be noted that, in the embodiment of the present invention, the charging voltage is a low-voltage switch charging circuit, and is optional, the operating voltage of the switch charging circuit is less than a preset voltage value, the preset voltage value can be 5V, and also can be other voltage values, the present invention does not limit this, as long as it is ensured that the switch charging circuit is a low-voltage switch charging circuit.

As shown in fig. 4, in the embodiment of the present invention, the switch charging circuit includes: the circuit comprises a first switching tube M1, a second switching tube M2, a third switching tube M3, an inductor, a first capacitor C1, a second capacitor C2, a driving circuit, a power supply selector and a control circuit; wherein,

the control end of the first switch tube M1 is electrically connected with the control circuit, the first end is electrically connected with the supply voltage end VBUS, and the second end is grounded through a first capacitor C1;

the control end of the second switch tube M2 is electrically connected with the driving circuit, the first end is electrically connected with the second end of the first switch tube M1, and the second end is electrically connected with the first end of the third switch tube M3;

the control end of the third switch tube M3 is electrically connected with the driving circuit, the first end is electrically connected with the second end of the second switch tube M2, and the second end is grounded;

a first end of the inductor L is electrically connected with a second end of the second switch tube M2, and a second end of the inductor L is electrically connected with a first end of the second capacitor C2;

a first end of the second capacitor C2 is electrically connected with a second end of the inductor L, the second end is grounded, and a first end of the second capacitor C2 is used as a voltage output end VBAT to charge a lithium ion battery;

the first input end of the power supply selector is electrically connected with the second end PMID of the first switch tube M1, the second input end of the power supply selector is electrically connected with the voltage output end VBAT, the output end Vmax is electrically connected with the driving circuit, and the larger value of the voltage value of the second end PMID of the first switch tube M1 and the voltage value of the voltage output end VBAT is selected as a supply voltage Vmax to be output to the driving circuit;

the control circuit controls the first switching tube M1 to operate in a first operating mode under a first preset condition, and controls the first switching tube M1 to operate in a second operating mode under a second preset condition, wherein the first switching tube M1 operates in a saturation region in the first operating mode; in the second operation mode, the first switch tube M1 operates in a linear amplification region. Wherein the second preset condition is that the switch charging circuit is in a stable working state

Specifically, the voltage value at the second terminal PMID of the first switching tube M1 is recorded as a first power supply voltage V1, the voltage value VBAT output by the voltage output terminal of the switching charging circuit is recorded as a second power supply voltage V2, when a voltage is input at the power supply voltage terminal VBUS, the switching charging circuit is in a charging state, the second power supply voltage V2 is smaller, and the power supply selector selects the first power supply voltage V1 as the power supply Vmax; when the supply voltage end VBUS end is suspended, the power supply selector selects the second supply voltage V2 as the supply power Vmax to maintain the normal operation inside the switch charging circuit.

Optionally, in a specific embodiment of the present invention, the first preset condition includes: the switch charging circuit is in a power-on phase. The switch charging circuit is in a power-on initial stage, which is a time period from the power-on of the VBUS to the completion of the establishment of the internal band gap reference of the switch charging circuit.

It should be noted that, in the embodiment of the present invention, the first end of the first switch tube M1 is electrically connected to the supply voltage VBUS, and the second end is electrically connected to the node PMID, so that in the switch charging circuit, the body diode formed by the first switch tube M1 points to the supply voltage VBUS and deviates from the node PMID.

When the switch charging circuit is in a first preset condition, the control circuit controls the first switching tube M1 to operate in a saturation region, so that the first power supply voltage V1 is controlled by a control end voltage of the first switching tube M1, so that the control circuit can control the voltage of the control end of the first switching tube M1 to make the first power supply voltage V1 be in a low voltage state; when the switch charging circuit is in the second preset condition, the control circuit controls the first switch tube M1 to work in the linear amplification area, the first supply voltage V1 is equal to the voltage value of the supply voltage end VBUS subtracts the voltage drop on the first switch tube M1, and the embodiment of the utility model provides a switch charging circuit is a low-voltage switch charging circuit, and the second preset condition is that the switch charging circuit is in a stable working state, therefore, the voltage of supply voltage end VBUS input at this moment is also low-voltage, thereby makes the first supply voltage V1 also is low-voltage. Therefore, in the switch charging circuit provided by the embodiment of the present invention, the second end of the first switch tube M1 is always kept low voltage and powered, so that the first power supply voltage V1 input by the power supply selector can be always low voltage and powered by using the second end of the first switch tube M1 as an input voltage of the power supply selector, and the subsequent second switch tube M2 and the subsequent third switch tube M3 can both adopt low voltage power tubes, so as to reduce the cost of the switch charging circuit.

Furthermore, the embodiment of the utility model provides an among the switch charging circuit, because node PMID's voltage remains the low-voltage throughout, can not because of drive circuit needs the current spike of hundreds of milliamperes rank and the great floating appears when driving second switch tube M2 and third switch tube M3 switch, thereby makes among the switch charging circuit that the embodiment provided, first supply voltage is comparatively stable, has solved among the prior art because drive circuit needs the current spike of hundreds of milliamperes rank when driving second switch tube M2 and third switch tube M3 switch, and has leaded to power supply Vmax appears unstable phenomenon, causes the unusual problem of switch charging circuit work.

Furthermore, the embodiment of the present invention provides a switch charging circuit, further including a first capacitor C1, the first capacitor C1 one end is electrically connected to the second end of the first switch tube M1, and the other end is grounded, so that when the voltage at the second end of the first switch tube M1 (i.e. the first power supply voltage) floats, the voltage at the second end of the first switch tube M1 is stabilized by the charging and discharging of the first capacitor C1, thereby further reducing the voltage floating of the first power supply voltage.

Therefore, the embodiment of the utility model provides a switch charging circuit cost is lower, does drive circuit etc. provide operating voltage's internal power supply Vmax's voltage comparatively stable.

Specifically, on the basis of the above embodiment, in an embodiment of the present invention, as shown in fig. 5, the control circuit includes:

a first voltage branch, the first voltage branch comprising: an input end Vdd of the amplifying circuit is electrically connected with the supply voltage end VBUS, and an output end Vcp of the amplifying circuit is electrically connected with the control end of the first switching tube M1;

a second voltage branch, the second voltage branch comprising: the first zener diode D1, the control switch S and the control chip, wherein the first end of the first zener diode D1 is electrically connected with the first end of the control switch S, the second end of the first zener diode D1 is electrically connected with the control end of the first switch tube M1, the control end of the control switch S is electrically connected with the control chip, and the second end of the control switch S is grounded;

the control chip controls the control switch S to be switched on under the first preset condition, and controls the control switch S to be switched off under the second preset condition.

It should be noted that, in the embodiment of the present invention, the amplifying circuit is used for amplifying the voltage Vdd inputted from its input end and then outputting it, optionally, the voltage Vcp of the output end of the amplifying circuit may be twice of the voltage at the input end of the amplifying circuit, and may also be other multiples of the voltage at the input end of the amplifying circuit. Optionally, the amplifying circuit is a charge pump. However, the present invention is not limited to this, and the specific conditions are determined.

The operation of the switch charging circuit will be described below by taking an example in which the voltage at the output terminal of the amplifying circuit is twice the voltage at the input terminal of the amplifying circuit.

It should be noted that, in an embodiment of the present invention, the default state of the control switch S is a closed state, but the present invention is not limited thereto, and in other embodiments of the present invention, the default state of the control switch S may also be an open state, as the case may be.

In the embodiment of the present invention, when the switch charging circuit works specifically, the power supply voltage terminal VBUS starts to be powered on, the voltage of the power supply voltage terminal VBUS increases gradually from zero to the working voltage of the switch charging circuit, in this process, the control switch S is in the closed state, the input voltage Vdd of the amplifying circuit increases gradually, the voltage Vcp of the output terminal of the amplifying circuit also increases gradually, the voltage of the second terminal of the first switch tube M1 increases gradually until the voltage Vcp of the output terminal of the amplifying circuit is greater than the breakdown voltage of the first zener diode D1, the first zener diode D1 is broken down, and thereafter, the voltage Vdd of the input terminal of the amplifying circuit increases again, the voltage Vcp of the output terminal of the amplifying circuit does not increase any more, but is stabilized at a fixed voltage value by the first zener diode D1, the voltage at the second terminal of the first switch tube M1 is controlled by the control terminal thereof, so that the voltage at the second terminal of the first switch tube M1 is also stabilized at a fixed value and does not change with the change of the supply voltage terminal VBUS until the switch charging circuit is powered up.

It should be noted that, since the breakdown voltage of the first zener diode D1 is about 5.6V, depending on the specific manufacturing process, optionally, in an embodiment of the present invention, the operating voltage of the switch charging circuit is 5V, but the present invention is not limited thereto, and is specifically determined as the case may be.

After the switch charging circuit is powered on, the control chip controls the control switch S to be switched off, the voltage Vcp at the output end of the amplifying circuit is released and is increased to be twice of the voltage Vdd at the input end of the amplifying circuit, the first switch tube M1 is driven, the first switch tube M1 works in a linear amplification area, and the switch charging circuit enters a stable working state.

It should be noted that, when the first switch tube M1 operates in the linear amplification region, the output current (i.e., the current output by the second terminal) of the first switch tube M1 increases in multiples with the increase of the input current (i.e., the current at the input terminal of the first switch tube M1), but the voltage at the second terminal of the first switch tube M1 is equal to the voltage of the supply voltage terminal VBUS minus the voltage drop between the first terminal and the second terminal of the first switch tube M1, so that, in the operation process of the switch charging circuit provided by the embodiment of the present invention, even though the second switch tube M2 and the third switch tube M3 perform the switching action, a larger current is required, and as long as the voltage value of the supply voltage terminal VBUS is not changed, the voltage at the second terminal of the first switch tube M1 is a stable value and does not change with the change of the current flowing through the first switch tube M1.

Optionally, on the basis of the above embodiment, in an embodiment of the present invention, as shown in fig. 5, the switch charging circuit further includes:

the band-gap reference circuit is electrically connected with the input end of the control chip and the output end of the power supply selector, wherein the output end of the power supply selector provides working voltage for the band-gap reference circuit; the band-gap reference circuit is used for detecting the power-on state of the switch charging circuit, and outputting a first control instruction when the power-on of the switch charging circuit is completed; and the control chip responds to the first control instruction and controls the control switch S to be switched off.

It should be noted that, in the above embodiment, the bandgap reference circuit is used to detect the power-on state of the switching charging circuit, and may also provide a reference signal for a driving circuit and other component circuits in the switching charging circuit. Since the internal structure and operation principle of the bandgap reference circuit are well known to those skilled in the art, the present invention is not described in detail herein. And the utility model provides a band gap reference circuit and the difference of the band gap reference circuit among the current charging chip are in band gap reference circuit still with the control chip electricity is connected when the electricity was accomplished on the switch charging circuit, export first control command and give control chip, so that control chip responds first control command, control switch S disconnection.

It should be further noted that, in any of the above embodiments, the input terminal of the amplifying circuit is directly electrically connected to the supply voltage terminal VBUS, that is, the voltage of the supply voltage terminal VBUS is directly used as the voltage Vdd at the input terminal of the amplifying circuit, so that the operating voltage of the amplifying circuit is relatively high, the power consumption is relatively high, and the requirement on the maximum operating voltage that can be borne by each component element in the amplifying circuit is relatively high.

In order to reduce the power consumption of the amplifying circuit and the requirement for the maximum operating voltage that each component in the amplifying circuit can bear, on the basis of the above embodiment, in an embodiment of the present invention, as shown in fig. 6, the first voltage branch further includes: the first resistor R1 is located between the supply voltage end VBUS and the amplifying circuit, so that the first resistor R1 is used for voltage division, the voltage of the input end of the amplifying circuit is equal to the voltage output by the supply voltage end VBUS minus the voltage drop of the first resistor R1, and therefore the power consumption of the amplifying circuit is reduced, and the requirement on the maximum working voltage which can be borne by each component element in the amplifying circuit is reduced.

It should be noted that, because the capability of the first resistor R1 for adjusting voltage is relatively limited, when an abnormally high voltage occurs at the supply voltage end VBUS, even if the first resistor R1 shares a part of the voltage drop, the voltage at the input end of the amplifying circuit may still be relatively high, based on this, on the basis of the above embodiment, in an embodiment of the present invention, as shown in fig. 7, the first voltage branch further includes: and a second zener diode D2, wherein one end of the second zener diode D2 is electrically connected to the first resistor R1 and the common end of the amplifying circuit, and the other end is grounded. In the embodiment of the present invention, when supply voltage end VBUS appears unusual high pressure, the voltage Vdd of amplifier circuit input is also higher, at this moment, second zener diode D2 is punctured, the voltage Vdd of amplifier circuit's input is stabilized at a fixed value (the breakdown voltage of second zener diode D2), thereby will amplifier circuit's operating voltage control is in second zener diode D2's breakdown voltage within range, further reduce amplifier circuit's consumption, it is right to reduce the maximum operating voltage requirement that each component element can bear among the amplifier circuit.

On the basis of any one of the above embodiments, in an embodiment of the present invention, the first preset condition further includes: the switch charging circuit generates an abnormal event. Wherein the abnormal event is that the switch charging circuit has an error state, and includes: an OVP (Over Voltage Protection) event, an OTP (Over temperature Protection) event, an uvlo (under Voltage Lock out) event, and the like, wherein the OVP event means that the Voltage of the supply Voltage terminal VBUS is too high; the OTP event refers to the temperature of the switch charging circuit being too high; UVLO events refer to a power source at the supply voltage terminal VBUS being too low or suddenly unplugged.

Optionally, on the basis of the above embodiment, in an embodiment of the present invention, as shown in fig. 8, the switch charging circuit further includes: and the protection circuit is electrically connected with the input end of the control chip and the output end Vmax of the power supply selector, the output end Vmax of the power supply selector provides working voltage for the protection circuit, the protection circuit is used for monitoring the working state of the switch charging circuit, when the working state of the switch charging circuit generates an abnormal event, a second control instruction is output, and the control chip responds to the second control instruction and controls the control switch S to be closed.

It should be noted that, since the internal specific structure and the operation principle of the protection circuit are well known to those skilled in the art, the present invention is not described in detail herein. And the utility model provides a protection circuit and the difference part of the protection circuit among the current charging chip lie in protection circuit still with the control chip electricity is connected when the operating condition of switch charging circuit takes place the abnormal event, output second control command gives control chip, so that control chip responds second control command, control switch S disconnection.

As shown in fig. 9, fig. 9 shows a timing signal diagram of a switch charging circuit according to an embodiment of the present invention, and the switch charging circuit according to the embodiment of the present invention is described below with reference to fig. 9.

In operation, the power supply voltage terminal VBUS starts to be powered up, the voltage of the power supply voltage terminal VBUS gradually increases from zero to the operating voltage of the switch charging circuit, in the process, the control switch S is in a closed state (as shown in fig. 10), the input terminal voltage Vdd of the amplifying circuit gradually increases, the voltage Vcp of the output terminal of the amplifying circuit also gradually increases, the voltage of the second terminal PMID of the first switching tube M1 gradually increases until the voltage Vcp of the output terminal of the amplifying voltage is greater than the breakdown voltage of the first zener diode D1, the first zener diode D1 is broken down, thereafter, the voltage Vdd of the input terminal of the amplifying circuit further increases, the voltage Vcp of the output terminal of the amplifying circuit does not increase, but is stabilized at a fixed voltage value by the first zener diode D1, and the voltage of the second terminal PMID of the first switching tube M1 is controlled by the control terminal thereof, therefore, the voltage of the second terminal PMID of the first switch tube M1 is also stabilized at a fixed value and no longer varies with the variation of the supply voltage terminal VBUS until the switch charging circuit is powered up.

After the switch charging circuit is powered on, the control chip controls the control switch S to be turned off, the control switch S is in an off state (as shown in fig. 11), the voltage Vcp at the output end of the amplifying circuit is released and is increased to twice the voltage Vdd at the input end of the amplifying circuit, the first switch tube M1 is driven, the first switch tube M1 works in a linear amplification area, and the switch charging circuit enters a stable working state.

When the supply voltage terminal of the switch charging circuit abnormally increases, the control chip controls the control switch S to close, the control switch S is in a closed state (as shown in fig. 10), the first zener diode D1 is broken down, the voltage Vcp at the output terminal of the amplifying circuit continues to be stabilized at a fixed voltage value by the first zener diode D1, and the voltage at the second terminal PMID of the first switch tube M1 is controlled by the control terminal thereof, so that the voltage at the second terminal PMID of the first switch tube M1 is also stabilized at a fixed value and does not change with the change of the supply voltage VBUS terminal until the switch charging circuit returns to a normal operating state.

It should be noted that, in the embodiment of the present invention, when the supply voltage terminal of the switch charging circuit is abnormally increased, the second zener diode D2 is also broken down, the voltage Vdd at the input terminal of the amplifying circuit is stabilized at a fixed voltage value by the second zener diode D2, so as to prevent the amplifying circuit from being damaged due to the abnormal increase of the supply voltage terminal of the switch charging circuit.

On the basis of any one of the above embodiments, in an embodiment of the present invention, as shown in fig. 12, the switch charging circuit further includes: a sampling resistance Rsns between the inductance L and the second capacitance C2; a sampling circuit (not shown in the figure) for collecting the signal on the sampling resistor Rsns; the driving circuit also adjusts the duty ratio of the second switching tube M2 and/or the third switching tube M3 based on the control instruction output by the sampling circuit so as to maintain the voltage of the voltage output end of the switch charging circuit stable.

In addition, the switch charging circuit can also comprise other peripheral circuits such as a loop control circuit and the like. To this end, the present invention is not repeated in detail.

On the basis of any one of the above embodiments, in an embodiment of the present invention, as shown in fig. 13, the charge pump includes: a ring oscillator, a first composition leg and a second composition leg, the first composition leg comprising: a first inverter G1, a third capacitor C3, a fourth switch tube M4 and a fifth switch tube M5, wherein the second component branch comprises: a second inverter G2, a third inverter G3, a fourth capacitor C4, a sixth switching tube M6 and a seventh switching tube M7; wherein,

a first end of the first phase inverter G1 is electrically connected to the ring oscillator, a second end of the first phase inverter G1 is electrically connected to the third capacitor C3, the other end of the third capacitor C3 is electrically connected to a control end of the fourth switching tube M4 and to a control end of a fifth switching tube M5, a first end of the fourth switching tube M4 is electrically connected to a second end of the fifth switching tube M5, a second end of the fourth transistor M4 is an input end of the charge pump, and a first end of the fifth switching tube M5 is an output end of the charge pump;

the first end of the second phase inverter G2 is electrically connected to the ring oscillator, the second end is electrically connected to the first end of the third phase inverter G3, the second end of the third phase inverter G3 is electrically connected to the fourth capacitor C4, the other end of the fourth capacitor C4 is electrically connected to the control terminal of the sixth switch tube M6, and is electrically connected to the control terminal of the seventh switch tube M7, the first end of the sixth switch tube M6 is electrically connected to the second terminal of the seventh switch tube M7, the second end of the sixth transistor M6 is electrically connected to the second terminal of the fourth switch tube, which is also the input terminal of the charge pump, the first end of the seventh switch tube M7 is electrically connected to the first terminal of the fifth switch tube M5, which is also the output terminal of the charge pump.

Optionally, the ring oscillator includes: a third component branch comprising a fourth inverter G4, a fifth inverter G5 and a sixth inverter G6 connected in series in this order, a fourth component branch comprising a seventh inverter G7, an eighth inverter G8 and a second resistor R2 connected in series in this order, and a fifth capacitor C5, wherein,

one end of the fifth capacitor C5 is grounded, and the other end is electrically connected with the third component branch and the fourth component branch;

a first terminal of a fourth inverter G4 is electrically connected to the fifth capacitor C5, a second terminal of the fourth inverter G4 is electrically connected to a first terminal of the fifth inverter G5, a second terminal of the fifth inverter G5 is electrically connected to a first terminal of a sixth inverter G6, and a second terminal of the sixth inverter G6 is electrically connected to the first and second component branches for an output terminal of the ring oscillator;

a first end of the seventh inverter G7 is an output end of the ring oscillator, and is electrically connected to the first component branch and the second component branch, a second end of the seventh inverter G7 is electrically connected to a first end of the eighth inverter G8, a second end of the eighth inverter G8 is electrically connected to a second resistor R2, and another end of the second resistor R2 is electrically connected to the fifth capacitor C5.

In other embodiments of the present invention, the amplifying circuit or the charge pump may have other implementation manners, which is not limited by the present invention, and is determined according to the circumstances.

To sum up, the embodiment of the utility model provides an among the switch charging circuit, the second end of first switch tube M1 is in the low-voltage electrified state all the time, and utilizes the second end of first switch tube M1 is as the first supply voltage of power selector switch charging circuit during operation, for drive circuit etc. provide operating voltage's internal power supply Vmax's voltage, the voltage is comparatively stable, and the cost is lower.

In the description, each part is described in a progressive manner, each part is emphasized to be different from other parts, and the same and similar parts among the parts are referred to each other.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A switch charging circuit for charging a lithium ion battery, wherein the operating voltage of the switch charging circuit is less than a predetermined voltage value, the charging circuit comprising: the circuit comprises a first switching tube, a second switching tube, a third switching tube, an inductor, a first capacitor, a second capacitor, a driving circuit, a power selector and a control circuit; wherein,

2. The switched charging circuit of claim 1, wherein the first preset condition comprises: the switch charging circuit is in a power-on stage; the second preset condition includes: the switch charging circuit is in a stable working state.

3. The switched charging circuit of claim 1, wherein the control circuit comprises:

4. The switched charging circuit of claim 3, further comprising:

the band-gap reference circuit is electrically connected with the input end of the control chip and the output end of the power supply selector, wherein the output end of the power supply selector provides working voltage for the band-gap reference circuit; the band-gap reference circuit is used for detecting the power-on state of the switch charging circuit, and outputting a first control instruction when the power-on of the switch charging circuit is completed; and the control chip responds to the first control instruction and controls the control switch to be switched off.

5. The switched charging circuit of claim 3, wherein the first voltage branch further comprises: a first resistor between the supply voltage terminal and the amplification circuit.

6. The switched charging circuit of claim 5, wherein the first voltage branch further comprises:

and one end of the second Zener diode is electrically connected with the first resistor and the common end of the amplifying circuit, and the other end of the second Zener diode is grounded.

7. The switched charging circuit of claim 3, wherein the amplification circuit is a charge pump.

8. The switched charging circuit of any of claims 2-7, wherein the first predetermined condition further comprises: the switch charging circuit generates an abnormal event.

9. The switched charging circuit of any of claims 3-7, further comprising:

the protection circuit is electrically connected with the input end of the control chip and the output end of the power supply selector, the output end of the power supply selector provides working voltage for the protection circuit, the protection circuit is used for monitoring the working state of the switch charging circuit, when the working state of the switch charging circuit generates an abnormal event, a second control instruction is output, and the control chip responds to the second control instruction and controls the control switch to be closed.

10. The switched charging circuit of claim 1, further comprising:

a sampling resistor between the inductor and the second capacitor;

the sampling circuit is used for acquiring signals on the sampling resistor;

the driving circuit also adjusts the duty ratio of the second switching tube and/or the third switching tube based on the control instruction output by the sampling circuit so as to maintain the voltage of the voltage output end of the switch charging circuit stable.