TWI825796B - Charger circuit - Google Patents

Abstract

The present invention discloses a charger circuit, including: a power stage circuit configured to operably operate at least one power switch according to an operation signal to convert an input power to an output power via an inductor to charge a battery and/or to be provided for a load, wherein the output power includes a charging power and/or a load power; a control circuit coupled with the power stage circuit and configured to operably generate the operation signal according to a voltage amplifying signal; and a voltage error amplifier circuit configured to operably compare a voltage sensing signal relevant to a charging voltage of the charging power or a load voltage of the load power with a voltage reference level in a voltage hysteresis mode in a discontinuous conduction mode (DCM), so as to generate the voltage amplifying signal; wherein the control circuit adjusts the charging voltage or the load voltage according to the voltage amplifying signal, so as to keep the charging voltage or the load voltage in a predetermined range.

Description

Charging circuit

The present invention relates to charging circuits, and in particular to charging circuits that control charging voltage or load voltage within a preset range.

Please refer to FIG. 1A , which shows a schematic waveform diagram of the charging voltage Vbat and the charging current Ibat in three operating modes (precharge mode, constant current mode and constant voltage mode) of a conventional charging circuit for charging a rechargeable battery. During the charging process, the changes in charging voltage Vbat and charging current Ibat are shown in Figure 1A. In the constant current mode, the charging voltage Vbat continues to increase. When the charging voltage Vbat reaches the preset threshold, the operating mode of the charging circuit changes to the constant voltage mode. In the constant voltage mode, the charging current Ibat decreases with time. When the charging current Ibat decreases to a preset level, the charging circuit needs to choose to operate in a discontinuous conduction mode (DCM) in the constant voltage mode. , if operated in continuous conduction mode (CCM, continuous conduction mode), it will cause negative current and cause current to flow backward, thus damaging the circuit. Selecting operation in discontinuous conduction mode improves efficiency, reduces switching losses, and avoids current backflow.

FIG. 1B is a schematic diagram showing the transient response waveform of a conventional charging circuit operating in the aforementioned discontinuous conduction mode. The charging voltage Vbat and switching node voltage VLX of this conventional charging circuit are shown in Figures 1B and 1C. In general applications, the charging circuit not only charges the rechargeable battery, but also supplies power to the load. As shown in Figure 1B, when the charging circuit operates in discontinuous conduction mode, The charging current Ibat is reduced to the preset level. If the load is light load, it can be seen from the waveform diagram that this conventional charging circuit is controlled by pulse skipping. If the control of the charging voltage Vbat is not accurate enough, the charging time will be too long. On the other hand, when the load is unstable, such as when the load changes from light load to heavy load, the transient response will cause the charging voltage Vbat to instantly decrease, and uneven ripples will easily occur. It can be seen from the transient response waveform diagram that when a heavy load comes, the load cannot change from the pulse omission mode to other pulse width modulation control modes in a short time. Because the power supply is not fast enough, the load voltage will drop by about 1 volt, which also causes the wrong selection of the charging circuit operating mode.

In view of this, the present invention aims at the above-mentioned shortcomings of the prior art and proposes a charging circuit that can accurately control the charging voltage, improve charging efficiency and enhance transient response.

In one aspect, the present invention provides a charging circuit including: a power stage circuit for operating at least one of the power switches according to an operation signal to convert an input power supply into an output power supply via an inductor to charge the charging circuit. A battery is charged and/or supplied to a load, wherein the output power source includes a charging power source and/or a load power source, the charging power source includes a charging voltage and a charging current, the load power source includes a load voltage; a control circuit , coupled to the power stage circuit, for generating the operation signal according to a voltage amplification signal; and a voltage error amplification circuit for a voltage hysteresis mode in a discontinuous conduction mode (DCM, discontinuous conduction mode) Comparing a voltage sensing signal related to the charging voltage or the load voltage with a voltage reference level to generate the voltage amplification signal; wherein the control circuit adjusts the charging voltage or the load voltage according to the voltage amplification signal, so that The charging voltage or the load voltage is maintained within a predetermined range.

In one embodiment, the voltage reference level includes an upper voltage threshold and a lower voltage threshold, wherein the voltage error amplification circuit includes: a first voltage comparison circuit for comparing the voltage associated with the charging voltage or the load voltage. the voltage sensing signal and the upper voltage threshold; a second voltage comparison circuit for comparing the voltage sensing signal related to the charging voltage or the load voltage with the lower voltage threshold; and a logic circuit, wherein the third A voltage comparison circuit is used to generate a first voltage judgment signal based on the voltage sensing signal related to the charging voltage or the load voltage and the voltage upper limit threshold, and the second voltage comparison circuit is used to generate a first voltage judgment signal based on the voltage sensing signal related to the charging voltage. Or the voltage sensing signal of the load voltage and the voltage lower limit threshold generate a second voltage judgment signal, and the logic circuit is used to generate a voltage hysteresis signal based on the first voltage judgment signal and the second voltage judgment signal; When the voltage sensing signal related to the charging voltage or the load voltage rises from less than the upper voltage threshold to the upper voltage threshold, the voltage hysteresis signal switches to a consistent energy level, causing the power stage circuit to At least one power switch is non-conductive, causing the charging voltage or the load voltage to drop; when the voltage sensing signal related to the charging voltage or the load voltage starts to drop from the upper voltage threshold and reaches the lower voltage threshold , the voltage hysteresis signal switches to a disabled level, causing the charging circuit to switch to the current hysteresis mode of the discontinuous conduction mode, by controlling the at least one power switch in the power stage circuit to switch the inductor, and then The charging voltage or the load voltage is increased, thereby maintaining the charging voltage or the load voltage within the predetermined range between the upper voltage threshold and the lower voltage threshold.

In one embodiment, the first voltage comparison circuit and the second voltage comparison circuit are comparison circuits using automatic correction technology.

In one embodiment, the at least one power switch includes an upper bridge switch and a lower bridge switch. The upper bridge switch is coupled between the input power supply and the first end of the inductor. The lower bridge switch Coupled between the first end of the inductor and a ground potential, the second end of the inductor is coupled to the charging power source or the load power source.

In one embodiment, when the charging circuit switches to the current hysteresis mode of the discontinuous conduction mode, when an inductor current flowing through the inductor drops from a level of an upper current threshold to a lower current threshold, the The upper bridge switch is turned on and the lower bridge switch is not turned on, causing the inductor current to rise, thereby causing the charging voltage or the load voltage to rise at a first rising rate. When the inductor current rises from the level of the current lower limit threshold to When the current upper limit threshold is reached, the upper bridge switch is not turned on, and the lower bridge switch is turned on, causing the inductor current to decrease, thereby causing the charging voltage or the load voltage to increase at a second rising rate.

In one embodiment, the first rising rate is greater than the second rising rate.

In one embodiment, the average value of the inductor current is less than or equal to one-half of the upper current threshold.

In one embodiment, the lower current threshold is zero or a value slightly greater than zero, thereby maintaining the inductor current at a positive value.

In one embodiment, the input power source includes an input voltage, the output power source includes an output voltage, and the current lower limit threshold and the current upper limit threshold can be dynamically adjusted or adaptively adjusted according to the input voltage or the output voltage.

In one embodiment, the charging circuit further includes a discontinuous conduction mode determination circuit for determining the time point when the charging circuit switches to the discontinuous conduction mode.

In one embodiment, the input power source includes an input current, and the discontinuous conduction mode determination circuit includes: a current sensing circuit for sensing the input current, an upper bridge current flowing through the upper bridge switch, and a current flowing through the upper bridge switch. An inductor current of the inductor or a low-side current flowing through the low-side switch generates a current sensing signal; a transition threshold generation circuit for generating a transition threshold signal based on the operation signal and a reference voltage; and a comparison circuit for comparing the current sensing signal signal and the transition threshold signal. When the current sensing signal is less than the transition threshold signal, the charging circuit is switched to the discontinuous conduction mode.

In one embodiment, the control circuit generates an end signal to leave the discontinuous conduction mode when the charging voltage or the load voltage is not higher than a preset lower limit level.

In one embodiment, the charging circuit further includes a timing circuit for timing a timeout period when the voltage hysteresis signal is at the disable level, and the timing circuit confirms at an end point of the timeout period. Whether the voltage hysteresis signal is still at the disable level, if the voltage hysteresis signal is still at the disable level, the timing circuit generates an end signal to leave the discontinuous conduction mode.

In one embodiment, the charging circuit further includes a current error amplification circuit for comparing a charging current sensing signal related to the charging current with a charging current reference level to generate the current amplifying signal to The charging current is adjusted to a preset current.

In one embodiment, the charging circuit further includes a current limit circuit for comparing an input current sensing signal related to an input current of the input power supply with an input current reference level to generate the current limit. signal, when the input current sensing signal related to the input current is greater than the input current reference level, the control circuit executes an over-current protection mechanism according to the current limit signal.

In one embodiment, the input current comes from a universal serial bus or a wireless charging interface.

In one embodiment, the charging circuit further includes a voltage limiting circuit for comparing an input voltage sensing signal related to an input voltage of the input power supply with an input voltage reference level to generate the voltage limiting circuit. signal, when the input voltage sensing signal related to the input voltage is lower than the input voltage reference level, the control circuit executes a low-voltage mechanism according to the voltage limit signal.

In one embodiment, the input voltage comes from a universal serial bus or a wireless charging interface.

In one embodiment, the charging circuit further includes a temperature limit circuit for comparing a temperature sensing signal related to a load temperature with a temperature reference level to generate the temperature limit signal. When the temperature sensing signal of the load temperature is greater than the temperature reference level, the control circuit executes a high temperature protection mechanism according to the temperature limit signal.

In one embodiment, whenever the voltage sensing signal related to the charging voltage or the load voltage drops to the voltage lower limit threshold, the control circuit confirms that the voltage from the current error amplification circuit, the current limiting circuit, the Whether the corresponding priority control signal of the voltage limiting circuit or the temperature limiting circuit is at the enable level, if the corresponding priority control signal from the current error amplifier circuit, the current limiting circuit, the voltage limiting circuit and the temperature limiting circuit If any of the control rights signals is at the enable level, the control circuit generates an end signal to leave the discontinuous conduction mode.

In one embodiment, when the charging circuit operates in the discontinuous conduction mode, except when the voltage sensing signal drops to the voltage lower limit threshold, the disabling confirmation from the current error amplification circuit, the current limiting circuit, the The corresponding priority control signal of the voltage limiting circuit or the temperature limiting circuit thereby improves the accuracy of the charging voltage or the load voltage.

The advantage of the present invention is that the present invention can achieve a fixed ripple of the charging voltage and provide higher accuracy, and can make the timing of entering or leaving the discontinuous conduction mode more precise.

It will be easier to understand the purpose, technical content, characteristics and achieved effects of the present invention through detailed description of specific embodiments below.

20:Charging circuit

201: Power stage circuit

202:Control circuit

203: Voltage error amplifier circuit

204: Current error amplifier circuit

205:Current limiting circuit

206: Voltage limiting circuit

207: Temperature limit circuit

208:Drive unit

209: Discontinuous conduction mode judgment circuit

210: Timing circuit

2031a: First voltage comparison circuit

2031b: Second voltage comparison circuit

2032: Logic circuits

2091:Current sensing circuit

2092: Transition threshold generation circuit

2093:Comparison circuit

AICR_FB: Input current sensing signal

AICR_FLAG, CC_FLAG, CV_FLAG, MIVR_FLAG, TR_FLAG: priority control signal

AICR_REF: Input current reference level

BUSIN: Universal serial bus input

CC_FB: charging current sensing signal

CC_REF: charging current reference level

CO1: first voltage judgment signal

CO2: second voltage judgment signal

CV_FB: voltage sensing signal

CV_REF: voltage reference level

DCM_DIV_REF: Transition threshold signal

DCM_EN: discontinuous conduction mode judgment signal

DCM_REF: reference voltage

Drop_FLAG: Voltage floor flag signal

EAOa: current limit signal

EAOc: current amplified signal

EAOm: voltage limit signal

EAOt: temperature limit signal

EAOv: voltage amplified signal

GA, GB: drive signal

GA’, GB’, GM: operation signal

IA: upper bridge current

IB: lower bridge current

Ibat: charging current

Id: current sensing signal

Iin: input current

IL: inductor current

Iout: output current

Ith_FLAG: Current upper limit threshold flag signal

IthH: current upper limit threshold

IthL: current lower limit threshold

L: inductance

LX1: first end

LX2: Second end

MIVR_FB: Input voltage sensing signal

MIVR_REF: Input voltage reference level

Multi-Loop_FLAG: jamming flag signal

QA:Power switch/upper bridge switch

QB: Power switch/lower bridge switch

QM: switch

Tout: timeout period

TOUT_FLAG: timeout flag signal

TR_FB: Temperature sensing signal

TR_REF: temperature reference level

t1,t2: time point

Vbat: charging voltage

Vbat_Drop: Default bottom limit level

Vbat_HYS: voltage hysteresis signal

Vin: input voltage

VLX: switching node voltage

Vsys: load voltage

VthH: voltage upper limit threshold

VthL: voltage lower limit threshold

WCIN: Wireless charging interface input

FIG. 1A is a schematic diagram showing the waveforms of charging voltage and charging current in three operating modes of a conventional charging circuit for charging a rechargeable battery.

FIG. 1B is a schematic diagram showing a signal waveform of a conventional charging circuit.

FIG. 1C is a schematic diagram showing the transient response waveform of a conventional charging circuit.

FIG. 2 is a circuit block diagram showing a charging circuit according to an embodiment of the present invention.

FIG. 3 is a circuit block diagram showing a charging circuit according to an embodiment of the present invention.

FIG. 4 is a circuit schematic diagram showing a voltage error amplification circuit of a charging circuit according to an embodiment of the present invention.

FIG. 5 is a schematic diagram showing signal waveforms of related signals of a charging circuit in discontinuous conduction mode according to an embodiment of the present invention.

FIG. 6 is a schematic diagram showing signal waveforms of related signals of a charging circuit according to an embodiment of the present invention.

FIG. 7 is a schematic diagram showing signal waveforms of related signals of a charging circuit according to another embodiment of the present invention.

FIG. 8 is a schematic diagram showing signal waveforms of related signals of a charging circuit according to yet another embodiment of the present invention.

Figures 9A-9G illustrate buck, boost, buck-boost, and flyback power stage circuits that switch synchronous or asynchronous inductive power stage circuits.

Figure 10 shows an embodiment of an AC-DC conversion circuit.

The diagrams in the invention are schematic and are mainly intended to represent the coupling relationship between various circuits and the relationship between various signal waveforms. As for the circuits, signal waveforms and frequencies, they are not drawn to scale.

FIG. 2 is a circuit block diagram showing a charging circuit according to an embodiment of the present invention. As shown in Figure 2, the charging circuit 20 of the present invention includes a power stage circuit 201, a control circuit 202, a driving unit 208, a voltage error amplifier circuit 203, a current error amplifier circuit 204, a current limit circuit 205, a voltage limit circuit 206 and a temperature limit. Circuit 207. The power stage circuit 201 is used to operate at least one of the power switches according to the operation signals GA' and GB' to convert the input power into an output power through the inductor L for charging the battery and/or for use by the load. In one embodiment, the output power source includes a charging power source and/or a load power source. The output power supply includes the output current Iout and the output voltage. The charging power supply includes charging voltage Vbat and charging current Ibat, and the load power supply includes load voltage Vsys. The control circuit 202 is coupled to the power stage circuit 201 for generating operation signals GA' and GB' according to the voltage amplification signal EAOv, the current amplification signal EAOc, the current limit signal EAOa, the voltage limit signal EAOm and/or the temperature limit signal EAOt. . The driving unit 208 is coupled to the control circuit 202 for generating driving signals GA and GB according to the operating signals GA' and GB', and then operating at least one power switch QA and QB through the driving signals GA and GB.

The voltage error amplification circuit 203 compares the voltage sensing signal CV_FB related to the charging voltage Vbat or the load voltage Vsys with the voltage reference level CV_REF in the voltage hysteresis mode of the discontinuous conduction mode (DCM) to generate voltage amplification. Signal EAOv. The control circuit 202 adjusts the charging voltage Vbat or the load voltage Vsys according to the voltage amplification signal EAOv, so that the charging voltage Vbat or the load voltage Vsys is maintained within a predetermined range. The current error amplifier circuit 204 is used to convert the charging current related to the charging current Ibat into The sensing signal CC_FB is compared with the charging current reference level CC_REF to generate a current amplification signal EAOc to adjust the charging current Ibat to a preset current.

The current limiting circuit 205 is used to compare the input current sensing signal AICR_FB related to the input current Iin of the input power supply with the input current reference level AICR_REF to generate the current limiting signal EAOa. When the input current sensing signal AICR_FB related to the input current Iin is greater than the input current reference level AICR_REF, the control circuit 202 performs an over-current protection mechanism according to the current limit signal EAOa, such as stopping the operation of the charging circuit 20 to prevent the input current Iin from being too high. . As shown in Figure 2, the input current Iin comes from the universal serial bus input terminal BUSIN or the wireless charging interface input terminal WCIN.

The voltage limiting circuit 206 is used to compare the input voltage sensing signal MIVR_FB related to the input voltage Vin of the input power supply with the input voltage reference level MIVR_REF to generate the voltage limiting signal EAOm. When the input voltage sensing signal MIVR_FB related to the input voltage Vin is lower than the input voltage reference level MIVR_REF, the control circuit 202 executes a low-voltage mechanism according to the voltage limit signal EAOm, such as stopping the operation of the charging circuit 20 to prevent the charging circuit 20 from operating at The case of too low input voltage Vin. As shown in Figure 2, the input voltage Vin comes from the universal serial bus input terminal BUSIN or the wireless charging interface input terminal WCIN.

The temperature limit circuit 207 is used to compare the temperature sensing signal TR_FB related to the load temperature with the temperature reference level TR_REF to generate the temperature limit signal EAOt. When the temperature sensing signal related to the load temperature is greater than the temperature reference level, the control circuit 202 executes a high temperature protection mechanism according to the temperature limit signal EAOt, such as stopping the operation of the charging circuit 20 to prevent the charging circuit 20 from operating in an excessively high temperature environment. As shown in Figure 2, the voltage error amplifier circuit 203, the current error amplifier circuit 204, the current limit circuit 205, the voltage limit circuit 206 and the temperature limit The circuit 207 has corresponding priority control signals CV_FLAG, CC_FLAG, AICR_FLAG, MIVR_FLAG and TR_FLAG respectively.

As shown in FIG. 2 , at least one power switch includes an upper bridge switch QA and a lower bridge switch QB. The upper bridge switch QA is coupled between the input power supply and the first terminal LX1 of the inductor L, and the lower bridge switch QB is coupled between the first terminal LX1 of the inductor L and the ground potential. The second terminal LX2 of the inductor L is coupled to the charging power supply and/or the load power supply. The driving signals GA and GB are used to control the upper bridge switch QA and the lower bridge switch QB respectively to switch the first end LX1 of the inductor L between the input power supply and the ground potential. The switch QM is coupled between the load power supply and the charging power supply. The operation signal GM is used to operate the switch QM to determine whether the output power supply supplies the load and/or the rechargeable battery, or the rechargeable battery supplies power to the load.

The power stage circuit 201 shown in Figure 2 is a step-down power stage circuit in a switching inductance power stage circuit. According to the present invention, the power stage circuit 201 is not limited to a switching inductance power stage circuit, and can also be an AC-DC conversion circuit. The switching inductor power stage circuit may be, for example, a synchronous or asynchronous buck-type, boost-type, buck-boost type, or flyback type power stage circuit, as shown in FIGS. 9A-9G. FIG. 10 shows an embodiment in which the power stage circuit 201 is an AC-DC conversion circuit.

FIG. 3 is a circuit block diagram showing a charging circuit according to an embodiment of the present invention. As shown in FIG. 3 , the charging circuit 20 of the present invention further includes a discontinuous conduction mode determination circuit 209 , which is used to determine the time point when the charging circuit 20 switches to the discontinuous conduction mode. The discontinuous conduction mode judgment circuit 209 includes a current sensing circuit 2091, a transition threshold generating circuit 2092 and a comparison circuit 2093. The current sensing circuit 2091 is used to sense the inductor current IL, the input current Iin, the upper bridge current IA flowing through the upper bridge switch QA, the lower bridge current IB flowing through the lower bridge switch QB, or the upper bridge current flowing through the upper bridge switch QA. The combination of the current IA and the lower bridge current IB flowing through the lower bridge switch QB generates the current sensing signal Id. In this embodiment, the current sensing circuit 2091 is used to sense the input current Iin. Transition threshold generation The circuit 2092 is used to generate the transition threshold signal DCM_DIV_REF according to the operation signals GA' and GB' and the reference voltage DCM_REF. The comparison circuit 2093 is used to compare the current sensing signal Id and the transition threshold signal DCM_DIV_REF to generate a discontinuous conduction mode determination signal DCM_EN. When the current sensing signal Id is less than the transition threshold signal DCM_DIV_REF, the discontinuous conduction mode determination signal DCM_EN is at the enable level, causing the charging circuit 20 to switch to the discontinuous conduction mode. In one embodiment, the transition threshold generating circuit 2092 includes a P-type transistor and an N-type transistor connected in series and a reverse gate. In another embodiment, the transition threshold generating circuit 2092 includes an N-type transistor and an N-type transistor connected in series with each other.

FIG. 4 is a circuit schematic diagram showing a voltage error amplification circuit of a charging circuit according to an embodiment of the present invention. As shown in FIG. 4 , the voltage error amplification circuit 203 includes a first voltage comparison circuit 2031a, a second voltage comparison circuit 2031b and a logic circuit 2032. The first voltage comparison circuit 2031a is used to compare the voltage sensing signal CV_FB related to the charging voltage Vbat or the load voltage Vsys with the voltage upper limit threshold VthH, and the second voltage comparison circuit 2031b is used to compare the voltage sensing signal CV_FB related to the charging voltage Vbat or the load voltage Vsys. The voltage sensing signal CV_FB and the voltage lower limit threshold VthL. The first voltage comparison circuit 2031a is used to generate the first voltage judgment signal CO1 according to the voltage sensing signal CV_FB related to the charging voltage Vbat or the load voltage Vsys and the voltage upper limit threshold VthH. The voltage sensing signal CV_FB of the voltage Vbat or the load voltage Vsys and the voltage lower limit threshold VthL generate a second voltage determination signal CO2, and the logic circuit 2032 is used to generate a voltage hysteresis based on the first voltage determination signal CO1 and the second voltage determination signal CO2. signal Vbat_HYS, thereby generating a voltage amplification signal EAOv.

Please refer to Figure 4, Figure 2 and Figure 5 at the same time. When the voltage sensing signal CV_FB related to the charging voltage Vbat or the load voltage Vsys rises from less than the upper voltage threshold VthH to the upper voltage threshold VthH, the voltage hysteresis signal Vbat_HYS is switched to enable. level, so that at least one of the power switches QA and QB in the power stage circuit 201 is non-conductive, thereby causing the charging voltage Vbat or the load to The voltage sensing signal CV_FB of the voltage Vsys decreases. When the voltage sensing signal CV_FB related to the charging voltage Vbat or the load voltage Vsys starts to decrease from the upper voltage threshold VthH and reaches the lower voltage threshold VthL, the voltage hysteresis signal Vbat_HYS turns to the disabled level, causing the charging circuit 20 to switch to discontinuous. The current hysteresis mode of the conduction mode controls the power switch QA or QB in the power stage circuit 201 to switch the first end LX1 of the inductor L between the input power supply and the ground potential, thereby making the charging voltage Vbat or the load voltage related The voltage sensing signal CV_FB of Vsys gradually rises. Through this mechanism, the voltage sensing signal CV_FB of the charging voltage Vbat or the load voltage Vsys is maintained within a predetermined range between the upper voltage threshold VthH and the lower voltage threshold VthL, that is, accurately The charging voltage Vbat or the load voltage Vsys is controlled to be maintained within a predetermined range to improve charging efficiency. In one embodiment, the first voltage comparison circuit 2031a and the second voltage comparison circuit 2031b are comparison circuits using automatic correction technology.

FIG. 5 is a schematic diagram showing signal waveforms of related signals of a charging circuit in discontinuous conduction mode according to an embodiment of the present invention. Please refer to FIG. 5 and FIG. 2 at the same time. When the charging circuit 20 switches to the current hysteresis mode of the discontinuous conduction mode, when the inductor current IL flowing through the inductor L drops from the level of the upper current threshold IthH to the lower current threshold IthL. , the upper bridge switch QA is turned on, and the lower bridge switch QB is not turned on, causing the inductor current IL to rise, and then causing the voltage sensing signal CV_FB related to the charging voltage Vbat or the load voltage Vsys to rise at the first rising rate; when the inductor current IL starts from the current When the level of the lower threshold IthL rises to the upper current threshold IthH, the upper current threshold flag signal Ith_FLAG turns to the enable level, triggering the upper bridge switch QA to become non-conductive and the lower bridge switch QB to conduct, causing the inductor current IL to decrease. Then, the voltage sensing signal CV_FB related to the charging voltage Vbat or the load voltage Vsys rises at the second rising rate. In one embodiment, the first rising rate is greater than the second rising rate. In one embodiment, the average value of the inductor current IL is less than or equal to one-half of the upper current threshold IthH.

It should be noted that the current lower limit threshold IthL is zero or a value slightly greater than zero, thereby maintaining the inductor current IL at a positive value to prevent the inductor current IL from turning into a negative value and causing current backflow. In one embodiment, the current lower limit threshold IthL and the current upper limit threshold IthH can be dynamically adjusted or adaptively adjusted according to the input voltage Vin or the output voltage.

FIG. 6 is a schematic diagram showing signal waveforms of related signals of a charging circuit according to an embodiment of the present invention. Please refer to Figure 6 or Figure 2 at the same time. When the voltage sensing signal CV_FB related to the charging voltage Vbat or the load voltage Vsys is not higher than the preset lower limit level Vbat_Drop, the voltage lower limit flag signal Drop_FLAG turns to the enable level. , the trigger control circuit 202 generates an end signal to leave the discontinuous conduction mode. Wherein, the preset bottom limit level Vbat_Drop is lower than the voltage lower limit threshold VthL. When the voltage sensing signal CV_FB is not higher than the preset lower limit level Vbat_Drop, if the charging circuit 20 operates in the current hysteresis mode of the discontinuous conduction mode, the voltage sensing signal CV_FB cannot be controlled between the upper voltage threshold VthH and the lower voltage threshold. between VthL and VthL indicates that the load changes from light load to heavy load, so it is necessary to leave the discontinuous conduction mode to enhance the transient response of the charging circuit 20 and avoid incorrect selection of the charging circuit operating mode.

FIG. 7 is a schematic diagram showing signal waveforms of related signals of a charging circuit according to another embodiment of the present invention. Please refer to FIG. 2 or FIG. 7 at the same time. The charging circuit 20 of the present invention further includes a timing circuit 210 for timing a timeout period Tout when the voltage hysteresis signal Vbat_HYS is at the disabled level. The timing circuit 210 is between the timeout period Tout. At the end time point t1, confirm whether the voltage hysteresis signal Vbat_HYS is still at the disable level. If the voltage hysteresis signal Vbat_HYS is still at the disable level, the time-out flag signal TOUT_FLAG turns to the enable level, indicating that the discontinuous conduction mode has exceeded When, the trigger control circuit 202 generates an end signal to leave the discontinuous conduction mode. Among them, when the average value of the output current Iout is exactly equal to the average value of the inductor current IL, the voltage sensing signal CV_FB remains near the voltage lower limit threshold VthL, and the voltage hysteresis signal Vbat_HYS remains in the disabled position. Accurate, indicating that all the inductor current IL is supplied to the load, and no current is used to charge the rechargeable battery. Therefore, when the time-out flag signal TOUT_FLAG turns to the enable level, the discontinuous conduction mode will end.

FIG. 8 is a schematic diagram showing signal waveforms of related signals of a charging circuit according to yet another embodiment of the present invention. Referring to FIG. 2 , FIG. 4 or FIG. 8 at the same time, whenever the voltage sensing signal CV_FB related to the charging voltage Vbat or the load voltage Vsys drops to the time point t1 and t2 when the voltage lower limit threshold VthL is reached, the control circuit 202 confirms that the signal from the current error amplifier circuit 204. Whether the corresponding priority control signals CC_FLAG, AICR_FLAG, MIVR_FLAG and TR_FLAG of the current limiting circuit 205, the voltage limiting circuit 206 or the temperature limiting circuit 207 are at the enable level. If, for example, at time t2, the control circuit 202 confirms that the current from the If any one of the corresponding priority control signals CC_FLAG, AICR_FLAG, MIVR_FLAG and TR_FLAG of the error amplifier circuit 204, the current limiting circuit 205, the voltage limiting circuit 206 and the temperature limiting circuit 207 is in the enable level, the interference flag signal Multi- Loop_FLAG changes to the enable level, triggering the control circuit 202 to generate an end signal to leave the discontinuous conduction mode.

Please refer to FIG. 2 again. When the charging circuit 20 operates in the discontinuous conduction mode, the priority control signals CC_FLAG and AICR_FLAG from the current error amplifier circuit 204, the current limiting circuit 205, the voltage limiting circuit 206 and the temperature limiting circuit 207 are disabled. , MIVR_FLAG and TR_FLAG. Only when the voltage sensing signal CV_FB drops to the voltage lower limit threshold VthL, the priority control signal CC_FLAG, AICR_FLAG, MIVR_FLAG and TR_FLAG is checked once, thereby improving the accuracy of the charging voltage Vbat or the load voltage Vsys. .

As mentioned above, the present invention provides a charging circuit, which uses a voltage error amplification circuit and a discontinuous conduction mode judgment circuit to fix the ripple of the charging voltage and provide higher accuracy, and can enter or leave the non-continuous conduction mode. The timing of continuous conduction mode is more precise.

The present invention has been described above with reference to the preferred embodiments. However, the above description is only to make it easy for those familiar with the art to understand the content of the present invention, and is not intended to limit the scope of the present invention. wide scope of rights. The various embodiments described are not limited to single application, but can also be used in combination. For example, two or more embodiments can be used in combination, and part of the components in one embodiment can also be used to replace those in another embodiment. Corresponding components. In addition, under the same spirit of the present invention, those skilled in the art can think of various equivalent changes and various combinations. For example, the present invention refers to "processing or calculating according to a certain signal or generating a certain output result", which is not limited to Depending on the signal itself, it also includes performing voltage-to-current conversion, current-to-voltage conversion, and/or ratio conversion on the signal when necessary, and then processing or calculating the converted signal to produce an output result. It can be seen from this that under the same spirit of the present invention, those skilled in the art can think of various equivalent changes and various combinations. There are many combinations, and they are not listed here. Accordingly, the scope of the present invention is intended to cover the above and all other equivalent changes.

20:Charging circuit

201: Power stage circuit

202:Control circuit

203: Voltage error amplifier circuit

204: Current error amplifier circuit

205:Current limiting circuit

206: Voltage limiting circuit

207: Temperature limit circuit

208:Drive unit

210: Timing circuit

AICR_FB: Input current sensing signal

AICR_FLAG, CC_FLAG, CV_FLAG, MIVR_FLAG, TR_FLAG: priority control signal

AICR_REF: Input current reference level

BUSIN: Universal serial bus input terminal

CC_FB: charging current sensing signal

CC_REF: charging current reference level

CV_FB: voltage sensing signal

CV_REF: voltage reference level

EAOa: current limit signal

EAOc: current amplified signal

EAOm: voltage limit signal

EAOt: temperature limit signal

EAOv: voltage amplified signal

GA, GB: drive signal

GA’, GB’, GM: operation signal

Ibat: charging current

Iin: input current

IL: inductor current

Iout: output current

L: inductance

LX1: first end

LX2: Second end

MIVR_FB: Input voltage sensing signal

MIVR_REF: Input voltage reference level

QA:Power switch/upper bridge switch

QB: Power switch/lower bridge switch

QM: switch

TR_FB: Temperature sensing signal

TR_REF: temperature reference level

Vbat: charging voltage

Vin: input voltage

Vsys: load voltage

WCIN: Wireless charging interface input

Claims (21)

A charging circuit, including: a power stage circuit for operating at least one of the power switches according to an operation signal to convert an input power supply into an output power supply through an inductor to charge and/or supply a battery For use with a load, wherein the output power source includes a charging power source and/or a load power source, the charging power source includes a charging voltage and a charging current, the load power source includes a load voltage; a control circuit coupled to the power stage circuit A connection is used to generate the operation signal according to a voltage error amplification signal; and a voltage error amplification circuit is used to compare the charging voltage in a voltage hysteresis mode of a discontinuous conduction mode (DCM). A voltage sensing signal of the voltage or the load voltage and a voltage reference level generate the voltage error amplification signal; wherein the control circuit adjusts the charging voltage or the load voltage according to the voltage amplification signal, so that the charging voltage or the The load voltage is maintained within a predetermined range. The charging circuit of claim 1, wherein the voltage reference level includes an upper voltage threshold and a lower voltage threshold, and the voltage error amplification circuit includes: a first voltage comparison circuit for comparing the charging voltage or the voltage sensing signal of the load voltage and the voltage upper limit threshold; a second voltage comparison circuit for comparing the voltage sensing signal related to the charging voltage or the load voltage and the voltage lower limit threshold; and a logic circuit, wherein the first voltage comparison circuit is used to generate a first voltage based on the voltage sensing signal related to the charging voltage or the load voltage and the upper voltage threshold. The second voltage comparison circuit is used to generate a second voltage judgment signal based on the voltage sensing signal related to the charging voltage or the load voltage and the voltage lower limit threshold, and the logic circuit is used to generate a second voltage judgment signal based on the first voltage judgment signal. A voltage judgment signal and the second voltage judgment signal generate a voltage hysteresis signal; wherein when the voltage sensing signal related to the charging voltage or the load voltage rises from less than the upper voltage threshold to the upper voltage threshold, the The voltage hysteresis signal is switched to a consistent energy level, so that at least one power switch in the power stage circuit is non-conductive, thereby causing the charging voltage or the load voltage to drop; wherein when the voltage related to the charging voltage or the load voltage The voltage sensing signal starts to decrease from the upper voltage threshold. When it reaches the lower voltage threshold, the voltage hysteresis signal switches to a disable level, causing the charging circuit to switch to the current hysteresis mode of the discontinuous conduction mode. By controlling The at least one power switch in the power stage circuit is used to switch the inductor, thereby increasing the charging voltage or the load voltage, thereby maintaining the charging voltage or the load voltage between the upper voltage threshold and the lower voltage threshold. within the predetermined range. The charging circuit of claim 2, wherein the first voltage comparison circuit and the second voltage comparison circuit are comparison circuits using automatic correction technology. The charging circuit of claim 2, wherein the at least one power switch includes an upper bridge switch and a lower bridge switch, the upper bridge switch is coupled between the input power source and the first end of the inductor, and the lower bridge switch Coupled between the first end of the inductor and a ground potential, the second end of the inductor is coupled to the charging power source or the load power source. The charging circuit of claim 4, wherein when the charging circuit switches to the current hysteresis mode of the discontinuous conduction mode, when an inductor current flowing through the inductor drops from a level of an upper current threshold to a current When the lower limit threshold is reached, the upper bridge switch is turned on and the lower bridge switch is not turned on, causing the inductor current to rise, thereby causing the charging voltage or the load voltage to increase with a first upper limit. The rising rate rises. When the inductor current rises from the current lower limit threshold to the current upper limit threshold, the upper bridge switch does not conduct, and the lower bridge switch conducts, causing the inductor current to decrease, thereby causing the charging voltage or The load voltage rises at a second rise rate. The charging circuit of claim 5, wherein the first rising rate is greater than the second rising rate. The charging circuit of claim 5, wherein the average value of the inductor current is less than or equal to half of the current upper limit threshold. The charging circuit of claim 5, wherein the current lower limit threshold is zero or a value slightly greater than zero, thereby maintaining the inductor current at a positive value. The charging circuit of claim 5, wherein the input power source includes an input voltage, the output power source includes an output voltage, and the current lower limit threshold and the current upper limit threshold can be dynamically adjusted or adapted according to the input voltage or the output voltage. adjust. The charging circuit of claim 4 further includes a discontinuous conduction mode judgment circuit for determining the time point when the charging circuit switches to the discontinuous conduction mode. The charging circuit of claim 10, wherein the input power source includes an input current, and the discontinuous conduction mode judgment circuit includes: a current sensing circuit for sensing the input current flowing through one of the upper bridge switches. The bridge current, an inductor current flowing through the inductor or a low-bridge current flowing through the low-bridge switch generates a current sensing signal; a transition threshold generating circuit is used to generate a current sensing signal based on the operating signal and a reference voltage. a transition threshold signal; and a comparison circuit for comparing the current sensing signal with the transition threshold signal. When the current sensing signal is less than the transition threshold signal, the charging circuit is switched to the discontinuous conduction mode. The charging circuit of claim 1, wherein the control circuit generates an end signal to leave the discontinuous conduction mode when the charging voltage or the load voltage is not higher than a preset bottom limit level. The charging circuit of claim 2 further includes a timing circuit for timing a timeout period when the voltage hysteresis signal is at the disable level, and when the timing circuit ends at one of the timeout periods, It is confirmed whether the voltage hysteresis signal is still at the disable level. If the voltage hysteresis signal is still at the disable level, the timing circuit generates an end signal to leave the discontinuous conduction mode. The charging circuit of claim 1 further includes a current error amplification circuit for comparing a charging current sensing signal related to the charging current with a charging current reference level to generate a current amplification signal, To adjust the charging current to a preset current. The charging circuit of claim 14, further comprising a current limiting circuit for comparing an input current sensing signal related to an input current of the input power supply with an input current reference level to generate a current Limiting signal, when the input current sensing signal related to the input current is greater than the input current reference level, the control circuit executes an over-current protection mechanism according to the current limiting signal. The charging circuit of claim 15, wherein the input current comes from a universal serial bus or a wireless charging interface. The charging circuit of claim 15, further comprising a voltage limiting circuit for comparing an input voltage sensing signal related to an input voltage of the input power supply with an input voltage reference level to generate a voltage Limiting signal, when the input voltage sensing signal related to the input voltage is lower than the input voltage reference level, the control circuit executes a low-voltage protection mechanism according to the voltage limiting signal. The charging circuit of claim 17, wherein the input voltage comes from a universal serial bus or a wireless charging interface. The charging circuit of claim 17 further includes a temperature limit circuit for comparing a temperature sensing signal related to a load temperature with a temperature reference level to generate a temperature limit signal that when related to When the temperature sensing signal of the load temperature is greater than the temperature reference level, the control circuit executes a high temperature protection mechanism according to the temperature limit signal. The charging circuit as claimed in claim 19, wherein whenever the voltage sensing signal related to the charging voltage or the load voltage drops to the voltage lower limit threshold, the control circuit confirms that the current error amplification circuit comes from the current error amplification circuit, the Whether the corresponding priority control signal of the current limit circuit, the voltage limit circuit or the temperature limit circuit is at the enable level, if it comes from the current error amplifier circuit, the current limit circuit, the voltage limit circuit and the temperature limit circuit If any of the corresponding priority control signals is at the enable level, the control circuit generates an end signal to leave the discontinuous conduction mode. The charging circuit of claim 20, wherein when the charging circuit operates in the discontinuous conduction mode, except when the voltage sensing signal drops to the voltage lower limit threshold, the confirmation from the current error amplification circuit is disabled, The corresponding priority control signal of the current limiting circuit, the voltage limiting circuit or the temperature limiting circuit thereby improves the accuracy of the charging voltage or the load voltage.

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