Battery charging control circuit for wireless charging receiver, wireless charging receiver and wireless charging device

Abstract

This application discloses a battery charging control circuit, a wireless charging receiver, and a wireless charging device for a wireless charging receiver, relating to the field of wireless charging technology. The circuit includes: an input terminal of a power stage connected to the rectified voltage of the wireless charging circuit, and an output terminal connected to a load; a control terminal of the power stage connected to a constant current loop and a constant voltage loop; an input terminal of the constant voltage loop connected to the output terminal of the power stage and an internal reference voltage signal; an input terminal of the constant current loop connected to the current sampling output terminal of the power stage and optionally connected to a constant voltage reference voltage and a constant current reference voltage; when communication is required, the MCU controls the circuit between the output terminal of the constant voltage loop and the control terminal of the power stage to disconnect, and controls the reference voltage of the constant current loop to switch to the constant voltage reference voltage; when communication is stopped, the MCU controls the circuit between the output terminal of the constant voltage loop and the control terminal of the power stage to connect, and controls the reference voltage of the second input terminal of the constant current loop to switch to the constant current reference voltage.

Description

Technical Field

[0001] This application relates to the field of wireless charging technology, and in particular to a battery charging control circuit, a wireless charging receiver, and a wireless charging device for use as a wireless charging receiver. Background Technology

[0002] According to the protocol, wireless charging receivers generally use amplitude modulation (AM) to transmit signals to the power transmitter. Based on the specific implementation and referring to the Qi 2.2 standard, there are currently three methods: capacitor modulation, current modulation, and Rac (ac-terminal resistance) modulation. During the 360kHz MPP (Multi-Purpose Circuit) phase, only current modulation and Rac modulation will be used. In principle, all three modulation methods achieve ASK modulation by changing the load current at the receiver.

[0003] The complete wireless charging device, such as Figure 1 and Figure 2 As shown, Figure 1 The wireless charging transmitter mainly consists of a full-bridge inverter, a transmitting coil (Ltx), and a resonant capacitor (Ctx) forming a power transmitting structure. Simultaneously, the circuit measures the coil voltage and samples the output current in the transmitting structure, connecting them to the voltage decoding circuit and the current decoding circuit respectively, and then sending them to the Qi protocol communication decoding to analyze the information transmitted from the receiving end. Figure 2 The wireless charging receiver consists of a 2.1 synchronous rectifier, a 2.2 ASK modulation circuit, and a 2.3 battery charging control circuit. The 2.1 synchronous rectifier converts the AC voltage from the transmitter to DC voltage. The 2.2 circuit controls the switching of the MASK switch based on the required ASK signal, introducing the communication modulation current Imod into the rectified filter current Irect, thus causing changes in the coil voltage and current at the transmitter. The 2.3 battery charging control circuit, following a typical lithium battery charging curve, requires at least a constant current loop (2.3.1) and a constant voltage loop (2.3.2). When the battery is charging, the battery voltage is lower than the full charge voltage, and the constant current loop plays a major role, controlling the MLDO to charge at the set maximum current value. As the battery approaches the full charge voltage, the constant voltage loop takes over, gradually reducing the charging current. The wireless charging receiver also connects to the battery as a load, and the battery serves as the direct power source for the phone, connecting to various voltage-dependent components within the phone via DC-DC power converters.

[0004] In specific mobile application scenarios, it's common for users to wirelessly charge their phones while simultaneously using them. When a user is using the phone, the screen refreshes at a frequency of 60Hz or higher. Since the screen typically uses row and column scanning, tests revealed a continuous pulse group of load current changes, Iload, that corresponds to the screen refresh rate.

[0005] like Figure 3 As shown, if the battery is in the constant current charging stage, the battery charging chip behaves like a constant current source, steadily charging the battery, thereby preventing the pulse load current Iload change from being transmitted to the wireless charging receiver. The load pulse current is directly provided by the battery, so the wireless charging receiver is not easily interfered with during the constant current charging stage.

[0006] like Figure 4 As shown, when the phone is charged to over 80%, the battery enters the constant voltage charging stage. Because the charging current is less than the set maximum current value, the constant current loop outputs zero, causing the diodes connected to the loop to stop conducting and lose their dominant control position. Figure 4 The diodes in this loop are marked with an "X". Therefore, only the constant voltage loop is active during the constant voltage charging phase. When the load changes, this pulse change in the load current, due to the lack of a constant current loop to limit it, causes the current Ichg controlling the battery charging chip to change with Iload. This ultimately causes the load current Irect at the wireless charging receiver to be affected by this pulse change, which is then superimposed on the load current Imod for normal communication, resulting in communication interference (e.g., ...). Figure 4 As shown in the image, this can cause wireless charging to stop or repeatedly restart. Summary of the Invention

[0007] The purpose of this application is to provide a battery charging control circuit, a wireless charging receiver, and a wireless charging device for a wireless charging receiver, which can solve the problem of wireless charging stopping or repeated restarts when using a terminal device during the constant voltage charging stage of the battery.

[0008] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides a battery charging control circuit for a wireless charging receiver, the circuit comprising: Power stage, MCU, constant current loop for battery charging, and constant voltage loop for battery charging; The input terminal of the power stage is connected to the voltage after wireless charging rectification; The output terminal of the power stage is connected to the load to provide charging voltage to the load; The control terminal of the power stage is connected to the output terminals of the constant current loop and the constant voltage loop, respectively. The first input terminal of the constant voltage loop is connected to the output terminal of the power stage, and the second input terminal of the constant voltage loop is connected to the internal reference voltage signal; The first input terminal of the constant current loop is connected to the output terminal of the power stage, and the second input terminal of the constant current loop can be selectively connected to a constant voltage reference voltage and a constant current reference voltage; the constant voltage reference voltage is the reference voltage corresponding to the magnitude of the charging current during the constant voltage charging phase; the constant current reference voltage is the reference voltage corresponding to the magnitude of the constant current charging current. The MCU is connected to the constant current loop and the constant voltage loop respectively; When the wireless charging receiver needs to communicate, the MCU controls the circuit between the output of the constant voltage loop and the control terminal of the power stage to disconnect, and controls the reference voltage of the second input terminal of the constant current loop to switch to a constant voltage reference voltage; when the wireless charging receiver stops communicating, the MCU controls the circuit between the output of the constant voltage loop and the control terminal of the power stage to connect, and controls the reference voltage of the second input terminal of the constant current loop to switch to a constant current reference voltage.

[0009] Secondly, this application provides a wireless charging receiver, which includes: a receiver coil, a resonant capacitor, a synchronous rectifier, an ASK modulation circuit, and a battery charging control circuit as described in the first aspect, connected in series.

[0010] Thirdly, this application provides a wireless charging device, which includes: a wireless charging transmitter and a wireless charging receiver as described in the second aspect.

[0011] According to the specific embodiments provided in this application, the following technical effects are disclosed: This application provides a battery charging control circuit, a wireless charging receiver, and a wireless charging device for a wireless charging receiver. By combining the constant voltage loop and constant current loop of traditional battery charging control with the communication signal of the wireless charging receiver, the constant voltage loop is disconnected during communication, and the charging voltage target of the constant current loop is adjusted to the reference voltage corresponding to the charging current during communication in the constant voltage charging phase. This reduces communication interference and improves the stability of wireless charging for mobile phones and other electronic products. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of the circuit structure of a wireless transmitter in a related technology provided in one embodiment of this application; Figure 2This is a schematic diagram of the circuit structure of a wireless receiver in a related technology provided in one embodiment of this application. Figure 1 ; Figure 3 This is a schematic diagram illustrating the transmission path of load current changes to communication interference in a constant current charging state of the battery, provided in one embodiment of this application. Figure 4 This is a schematic diagram illustrating the transmission path of load current changes to communication interference under constant voltage charging conditions of the battery, provided in one embodiment of this application. Figure 5 This is a schematic diagram of a battery charging control circuit for a wireless charging receiver, according to an exemplary embodiment. Figure 1 ; Figure 6 This is a schematic diagram of a battery charging control circuit for a wireless charging receiver, according to an exemplary embodiment. Figure 2 ; Figure 7 This is illustrated according to an exemplary embodiment, corresponding to Figure 5 and Figure 6 Specific embodiments illustration Figure 1 ; Figure 8 This is illustrated according to an exemplary embodiment, corresponding to Figure 5 and Figure 6 Specific embodiments illustration Figure 2 ; Figure 9 This is illustrated according to an exemplary embodiment, corresponding to Figure 5 and Figure 6 Specific embodiments illustration Figure 3 ; Figure 10 This is illustrated according to an exemplary embodiment, corresponding to Figure 5 and Figure 6 Specific embodiments illustration Figure 4 . Detailed Implementation

[0014] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0015] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0016] Figure 5 and Figure 6 This is a schematic diagram of a battery charging control circuit for a wireless charging receiver, according to an exemplary embodiment. Figure 5 As shown, the battery charging control circuit includes: Power stage, MCU, constant current loop and constant voltage loop; The input terminal of the power stage is connected to the rectified voltage VRECT of the wireless charging circuit. The output terminal of the power stage is connected to the load to provide a charging voltage VBAT to the load; The control terminal of the power stage is connected to the output terminals of the constant current loop and the constant voltage loop, respectively. The first input terminal of the constant voltage loop is connected to the output terminal of the power stage, and the second input terminal of the constant voltage loop is connected to the internal reference voltage signal Vbat_ref; The first input terminal of the constant current loop is connected to the output terminal of the power stage, and the second input terminal of the constant current loop can be selectively connected to the constant voltage reference voltage Ibat_cv_ref and the constant current reference voltage Ibat_cc_ref; the constant voltage reference voltage is the reference voltage corresponding to the magnitude of the charging current during the constant voltage charging phase communication; the constant current reference voltage is the reference voltage corresponding to the magnitude of the constant current charging current. The MCU is connected to the constant current loop and the constant voltage loop respectively; The MCU is used when the wireless charging receiver needs to communicate, such as Figure 5 As shown, the circuit between the output terminal of the constant voltage loop and the control terminal of the power stage is disconnected, and the reference voltage of the second input terminal of the constant current loop is switched to the constant voltage reference voltage Ibat_cv_ref; when the wireless charging receiver stops communication, the MCU is used as follows: Figure 6 As shown, the circuit between the output terminal of the constant voltage loop and the control terminal of the power stage is controlled to switch the reference voltage of the second input terminal of the constant current loop to the constant current reference voltage Ibat_cc_ref.

[0017] In one embodiment, the input terminal of the power stage is connected to the rectified voltage VRECT of wireless charging. VRECT is used as the energy input of the power stage. The control terminal of the power stage is controlled by the feedback of the constant current loop and the constant voltage loop to generate the VBAT output for charging the battery, which directly supplies power to the battery (load).

[0018] The first input of the constant voltage loop is connected to the output of the power stage to acquire the real-time battery voltage VBAT. The second input of the constant voltage loop is connected to the internal reference voltage signal Vbat_ref, which is the target full-charge voltage of the battery. During operation, VBAT and Vbat_ref are compared. When the battery voltage is close to the full-charge voltage, the constant voltage loop plays a leading role, controlling the battery charging current to gradually decrease during the constant voltage charging stage to prevent battery overcharging.

[0019] The first input of the constant current loop is connected to the power stage current sampling output to collect the real-time charging current. The second input is a switchable reference voltage port, supporting either a constant current reference voltage Ibat_cc_ref or a constant voltage reference voltage Ibat_cv_ref. The constant current loop samples the charging current at the battery terminal, limits the charging current to a set current value, and selects either Ibat_cc_ref or Ibat_cv_ref as the reference voltage. Ibat_cc_ref is the reference voltage corresponding to the set maximum charging current value during the constant current phase. Ibat_cv_ref is the reference voltage corresponding to the charging current value during the constant voltage charging phase, where Ibat_cc_ref > Ibat_cv_ref, and Ibat_cv_ref gradually decreases during the constant voltage charging phase; that is, Ibat_cv_ref slowly decreases as the constant voltage charging progresses.

[0020] The MCU, as the control core, is connected to the reference voltage switching terminals of the constant voltage loop and the constant current loop respectively. Based on the communication status of wireless charging, it outputs control signals to realize the switching of the working modes of the two loops.

[0021] When the wireless charging receiver needs to communicate (corresponding to Module=1), it will cut off the load interference path through two core operations to ensure stable communication. The specific workflow is as follows: 1. Control the reference voltage at the second input terminal of the constant current loop to switch to Ibat_cv_ref.

[0022] After the constant current loop is switched to Ibat_cv_ref, the charging current will be stabilized at the value corresponding to Ibat_cv_ref. At this time, the power stage is equivalent to a constant current source. The stable constant current source characteristics will block the current pulses of loads such as mobile phone screens from being transmitted to the VRECT side of the wireless charging receiver, thus avoiding interference with the communication modulation current Imod.

[0023] Through the above operations, the load current fluctuation of the wireless charging receiver during communication is suppressed, thereby enabling the transmitter to accurately identify the ASK modulated signal transmitted by the receiver, thus improving the anti-interference capability of communication.

[0024] 2. Control the constant pressure loop to stop working.

[0025] The MCU outputs a command to disconnect the circuit between the output terminal of the constant voltage loop and the control terminal of the power stage, cut off the control of the constant voltage loop, and let the constant voltage loop take off the dominant control position to eliminate the problem of the charging current fluctuating with the load during the constant voltage stage and avoid the load current pulse being superimposed on the communication modulation current.

[0026] When the wireless charging receiver stops communicating (corresponding to Module=0), the following two control operations will be performed: 1. Control the constant pressure loop to resume operation.

[0027] The MCU controls the circuit between the output of the constant voltage loop and the control terminal of the power stage, restoring the control of the constant voltage loop and allowing it to re-participate in the charging control.

[0028] At this point, the constant voltage loop will compare VBAT and Vbat_ref normally. When the battery voltage approaches the full charge voltage, the constant voltage loop will take the lead in control, gradually reducing the charging current to ensure that the battery voltage stabilizes near the target charging voltage and prevent overcharging.

[0029] 2. Control the reference voltage at the second input terminal of the constant current loop to switch to Ibat_cc_ref.

[0030] The constant current loop uses Ibat_cc_ref as a reference to limit the charging current to no more than Ibat_cc_ref, ensuring that the battery is charged within a safe current range.

[0031] At this point, the circuit resumes its normal constant voltage / constant current charging logic: when the battery voltage is low, the constant current loop dominates, charging with a constant large current; when the battery voltage is close to full charge, the constant voltage loop dominates, reducing the current and stabilizing the voltage.

[0032] In an embodiment, the implementation of the MCU controlling the disconnection of the circuit between the output terminal of the constant voltage loop and the control terminal of the power stage may include: 1. controlling the switch to turn on or off, 2. disabling the constant voltage loop, 3. increasing Vbat_ref, or 4. changing the resistor voltage division ratio, etc.

[0033] In the embodiment, the MCU controls the reference voltage at the second input terminal of the constant current loop to switch to Ibat_cv_ref or Ibat_cc_ref, which can be achieved by switching the reference voltage with a switch or adjusting the reference voltage with a DAC.

[0034] In one embodiment, such as Figure 7 As shown, the constant current loop includes: a first operational amplifier U1 and a first diode D1; The first input terminal of the first operational amplifier U1 is connected to the current signal collected by the output terminal of the power stage; The second input terminal of the first operational amplifier U1 can be selectively connected to a constant voltage reference voltage Ibat_cv_ref and a constant current reference voltage Ibat_cc_ref; The output terminal of the first operational amplifier U1 is connected to the anode of the first diode D1, and the cathode of the first diode D1 is connected to the control terminal of the power stage; The MCU is connected to the selection switch S control terminal connected to the second input terminal of the first operational amplifier U1. When the wireless charging receiver needs to communicate, the MCU controls the reference voltage of the second input terminal of the first operational amplifier U1 to switch to the constant voltage reference voltage Ibat_cv_ref. When the wireless charging receiver stops communicating, the MCU controls the circuit between the output terminal of the constant voltage loop and the control terminal of the power stage to be turned on, and controls the reference voltage of the second input terminal of the first operational amplifier U1 to switch to the constant current reference voltage Ibat_cc_ref.

[0035] The first input terminal of the first operational amplifier U1 is connected to the output terminal of the power stage and is used to acquire the sampling voltage of the real-time charging current. The second input terminal of the first operational amplifier U1 is a switchable reference voltage interface, which can be connected to Ibat_cv_ref or Ibat_cc_ref. The anode of the first diode D1 is connected to the output terminal of the first operational amplifier U1, and the cathode of the first diode D1 is connected to the control terminal of the first operational amplifier U1. The function of the first diode D1 is to control whether the output of the constant current loop applies to the power stage.

[0036] The MCU's control interface is connected to the control terminal of the selection switch S, which is connected to the second input terminal of the first operational amplifier U1 in the constant current loop, and is responsible for switching the reference voltage. The MCU's control interface is also connected to the control terminal of the output switch S in the constant voltage loop, and is responsible for controlling the on / off connection between the constant voltage loop and the power stage.

[0037] Workflow when the wireless charging receiver needs to communicate (Module=1): 1. Switch the reference voltage at the second input terminal of the first operational amplifier U1 in the constant current loop to Ibat_cv_ref.

[0038] The MCU controls the second input terminal of the first operational amplifier U1 to connect to the reference voltage Ibat_cv_ref, which is dedicated to communication during the constant voltage charging stage.

[0039] At this time, the first operational amplifier U1 compares the real-time sampled voltage with Ibat_cv_ref, and outputs a control signal to the power stage through the first diode D1 to stabilize the charging current at the value corresponding to Ibat_cv_ref. The stable constant current characteristic will block the current pulse of the load such as the mobile phone screen from being transmitted to the VRECT side, thus avoiding interference with the communication modulation current Imod.

[0040] 2. Disconnect the constant voltage loop from the power stage.

[0041] The MCU outputs a control signal to cut off the circuit path from the constant voltage loop output to the power stage control terminal. This step directly causes the constant voltage loop to exit charging control, avoiding the problem of charging current fluctuation with load during the constant voltage stage.

[0042] When communication stops (Module=0), the normal charging mode is restored, and the workflow is as follows: 1. Connect the constant voltage loop to the power stage.

[0043] The MCU outputs a control signal to restore the circuit path from the constant voltage loop output to the power stage control terminal. The constant voltage loop then rejoins the control, responsible for gradually reducing the charging current when the battery voltage is close to full charge, thus preventing overcharging.

[0044] 2. Switch the reference voltage at the second input terminal of the first operational amplifier U1 in the constant current loop to Ibat_cc_ref.

[0045] The MCU controls the second input terminal of the first operational amplifier U1 to switch back to the reference voltage Ibat_cc_ref of the constant current charging stage.

[0046] In one embodiment, such as Figure 7 As shown, the constant voltage loop includes: a second operational amplifier U2 and a second diode D2; the first input terminal of the second operational amplifier U2 is connected to the output terminal of the power stage, the second input terminal of the second operational amplifier U2 is connected to Vbat_ref, the output terminal of the second operational amplifier U2 is connected to the anode of the second diode D2, the anode of the second diode D2 is connected to the control terminal of the power stage, and the MCU is connected to the enable control terminal of the second operational amplifier U2.

[0047] In one implementation, such as Figure 8 As shown, the constant current loop further includes: a reference voltage selector M1, a sample and hold module, a first sampling resistor Rsense1, an inverter G1, and a first bias current I1; One end of the first sampling resistor Rsense1 is connected to the current sampling circuit, and the other end of the first sampling resistor Rsense1 is grounded. The non-inverting input terminal of the first operational amplifier U1 is connected between the first sampling resistor Rsense1 and the current sampling circuit; The first input terminal of the reference voltage selector M1 ( Figure 8 Terminal A is connected between the first sampling resistor Rsense1 and the current sampling circuit via a sample-and-hold (S / H) module; the sample-and-hold (S / H) module samples the voltage corresponding to the charging current sampling signal before communication and holds it as the constant voltage reference voltage Ibat_cv_ref; The second input terminal of the reference voltage selector M1 ( Figure 8 Terminal B in the diagram is connected to a constant current reference voltage. The output terminal of the reference voltage selector M1 ( Figure 8 The O terminal in the circuit is connected to the inverting input terminal of the first operational amplifier U1; The control terminal of the power stage is grounded through a first bias current I1; The cathode of the first diode D1 is connected between the control terminal of the power stage and the first bias current I1. The MCU is connected to the control terminal of the reference voltage selector M1 through the inverter G1. When the wireless charging receiver needs to communicate, the MCU controls the constant voltage loop to stop working and controls the circuit between the first input terminal and the output terminal of the reference voltage selector M1 to be connected. When the wireless charging receiver stops communicating, the MCU controls the constant voltage loop to resume working and controls the circuit between the second input terminal and the output terminal of the reference voltage selector M1 to be connected.

[0048] The reference voltage selector M1 is an analog switching device with two inputs (A and B) and one output (O). Terminal A is connected to the output of the sample-and-hold (S / H) module, terminal B is connected to the constant current reference voltage Ibat_cc_ref, and terminal O is connected to the inverting input of the first operational amplifier U1. The path selection is controlled by the MCU.

[0049] The input of the sample-and-hold (S / H) module is connected to the output of the current sampling circuit. Its function is to acquire and lock the sampling voltage corresponding to the real-time charging current Ibat_sense1 at the moment before communication, and use it as the reference voltage Ibat_cv_ref for the constant voltage communication stage.

[0050] The non-inverting input of the first operational amplifier U1 acquires the sampling voltage corresponding to the real-time charging current Ibat_sense1 output by the power stage. The inverting input of the first operational amplifier U1 is connected to the O terminal of the reference voltage selector M1, and the control signal is output through voltage comparison.

[0051] The anode of the first diode D1 is connected to the output terminal of the first operational amplifier U1, and the cathode of the first diode D1 is connected to the control terminal of the power stage, which is used to control whether the signal of the constant current loop is applied to the power stage.

[0052] The first sampling resistor Rsense1 is connected in series between the output terminal of the current sampling circuit and ground. When the real-time charging current flows through it, a voltage proportional to the real-time charging current is generated, which serves as the current sampling signal.

[0053] One end of the first bias current I1 is connected to the control terminal of the power stage, and the other end is grounded. It is used to provide a stable bias current for the power stage, and together with the constant current loop and the constant voltage loop, it constitutes the regulation and control of the power stage. Inverter G1 is optional and is used to adapt the logic definitions of constant voltage and constant current loops. When the wireless charging receiver needs to communicate (Module=1), it performs three key operations: 1. The sample-and-hold module locks the sampling voltage corresponding to the charging current Ibat_sense1 on the first sampling resistor Rsense1 just before communication. This voltage is then locked and output to terminal A of the reference voltage selector M1 as the reference voltage Ibat_cv_ref for the constant voltage communication phase. The current value corresponding to this voltage is the actual charging current before communication, which can avoid battery overcharging caused by sudden changes in load current.

[0054] 2. The MCU's control signal drives the reference voltage selector M1 to open the path between terminals A and O, sending the locked Ibat_cv_ref to the inverting input of the first operational amplifier U1. At this time, the constant current loop uses Ibat_cv_ref as a reference, and controls the power stage through the first operational amplifier U1 and the first diode D1 to stabilize the charging current at the locked value, blocking the fluctuation of the load current Iload from being transmitted to the VRECT side, thus avoiding interference with the communication modulation current Imod.

[0055] 3. Control the disconnection of the circuit between the output terminal of the constant voltage loop and the control terminal of the power stage.

[0056] The workflow resumes after communication stops (Module=0), following the normal charging mode: 1. The MCU outputs a control signal to restore the circuit path from the constant voltage loop output terminal to the power stage control terminal.

[0057] 2. The MCU's control signal drives the reference voltage selector M1 to open the path between terminals B and O, sending the constant current reference voltage Ibat_cc_ref to the inverting input of the first operational amplifier U1. At this time, the constant current loop uses Ibat_cc_ref as a reference to limit the charging current to no more than the set maximum value, ensuring that the battery is charged within a safe current range.

[0058] In one embodiment, as Figure 8 shown, the constant voltage loop includes: a second operational amplifier U2, a second diode D2, a first resistor Rfb1, and a second resistor Rfb2; One end of the first resistor Rfb1 is connected to the output end of the power stage; the other end of the first resistor Rfb1 is connected to one end of the second resistor Rfb2, and the other end of the second resistor Rfb2 is grounded; The first input end of the second operational amplifier U2 is connected between the first resistor Rfb1 and the second resistor Rfb2; The second input end of the second operational amplifier U2 is connected to an internal reference voltage signal Vbat_ref; The output end of the second operational amplifier U2 is connected to the anode of the second diode D2, and the cathode of the second diode D2 is connected between the control end of the power stage and the first bias current I1; The MCU is connected to the enable control end of the second operational amplifier U2 through the inverter G1. When communication is required at the wireless charging receiver end, the MCU controls the second operational amplifier U2 to stop working and controls the circuit between the first input end and the output end of the reference voltage selector M1 to conduct; when communication at the wireless charging receiver end stops, the MCU controls the second operational amplifier U2 to resume working and controls the circuit between the second input end and the output end of the reference voltage selector M1 to conduct.

[0059] When communication is required at the wireless charging receiver end, the Module signal is 1. After passing through the inverter G1, the second operational amplifier U2 in the constant voltage loop is not enabled, the control of the constant voltage loop is cut off, and at the same time, the reference voltage of the constant current loop is selected to the A port of the reference voltage selector M1. The signal of the A port is the voltage Ibat_sense1 corresponding to the charging current before sampling communication. The sample and hold (S / H) module is implemented using a well-known S / H (sample / hold, sample and hold circuit) and will not be elaborated here. When communication at the wireless charging receiver end stops, the Module signal is 0, the control of the constant voltage loop is restored, and the reference voltage of the constant current loop selects the B end of the reference voltage selector M1 to select the normal fixed-set constant current charging current. When the battery charging enters the constant voltage charging stage and Module = 0, at this time VBAT k = Vbat_ref, (k = Rfb2 / (Rfb1 + Rfb2)), the constant voltage loop plays a dominant role, reducing the charging current of the battery, Ibat_sense1 < Ibat_ref, and the output of the first operational amplifier U1 in the constant current loop is 0, causing the first diode D1 in the constant current loop to be reverse-biased, thereby exiting the control of the constant current loop.

[0060] In traditional battery chargers, the charging current gradually decreases during the constant voltage phase. If the charging current doesn't decrease, the battery's open-circuit voltage will continuously rise, and the battery's internal resistance will contribute to overvoltage issues. Therefore, during the communication phase, after disconnecting the constant voltage loop control, the set charging current needs to be reduced simultaneously to prevent battery overcharging. Because this current value gradually decreases during the CV phase, the charging current before communication needs to be used as a temporary reference current-voltage. By adding the above control adjustments, during the CV phase communication, fluctuations in the battery load are prevented from being transmitted to the VRECT terminal by the constant current loop, thereby improving anti-interference capabilities.

[0061] In one embodiment, such as Figure 9 As shown, the constant voltage loop includes: a third operational amplifier U3, a third diode D3, a third resistor Rfb3, a fourth resistor Rfb4, and a switch S; One end of the third resistor Rfb3 is connected to the output terminal of the power stage; the other end of the third resistor Rfb3 is connected to one end of the fourth resistor Rfb4, and the other end of the fourth resistor Rfb4 is grounded. The first input terminal of the third operational amplifier U3 is connected between the third resistor Rfb3 and the fourth resistor Rfb4; The second input terminal of the third operational amplifier U3 is connected to the internal reference voltage signal Vbat_ref; The output terminal of the third operational amplifier U3 is connected to the anode of the third diode D3 via switch S, and the cathode of the third diode D3 is connected between the control terminal of the power stage and the first bias current I1. The MCU is connected to the control terminal of the switch S. When the wireless charging receiver needs to communicate, the MCU controls the switch S to open, thereby connecting the circuit between the first input terminal and the output terminal of the reference voltage selector M1. When the wireless charging receiver stops communicating, the MCU controls the switch S to open, thereby connecting the circuit between the second input terminal and the output terminal of the reference voltage selector M1.

[0062] In one embodiment, such as Figure 10 As shown, the constant current circuit includes: an A / D module, a logic module, a first D / A module, a second sampling resistor Rsense2 and a second bias current I3, a first operational amplifier U1 and a first diode D1; One end of the second sampling resistor Rsense2 is connected to the output terminal of the current sampling circuit, and the other end of the second sampling resistor Rsense2 is grounded; The non-inverting input of the first operational amplifier U1 is connected between the second sampling resistor Rsense2 and the output of the power stage; One end of the A / D module is connected between the second sampling resistor Rsense2 and the output of the current sampling circuit; The other end of the A / D module is connected to the first input terminal of the logic module, the MCU is connected to the second input terminal of the logic module, and the first output terminal of the logic module is connected to the inverting input terminal of the first operational amplifier U1 through the first D / A module. The output terminal of the power stage is grounded through the second bias current; The output terminal of the first operational amplifier U1 is connected to the anode of the first diode D1, and the cathode of the first diode D1 is connected between the output terminal of the power stage and the second bias current. When the wireless charging receiver needs to communicate, the MCU controls the first output terminal of the logic module to output the constant voltage reference voltage digital signal corresponding to the constant voltage reference voltage Ibat_cv_ref, and the first D / A module converts the constant voltage reference voltage digital signal into the constant voltage reference voltage Ibat_cv_ref; when the wireless charging receiver stops communicating, the MCU controls the first output terminal of the logic module to output the constant current reference voltage digital signal corresponding to the constant current reference voltage Ibat_cc_ref, and the first D / A module converts the constant current reference voltage digital signal into the constant current reference voltage Ibat_cc_ref.

[0063] The second sampling resistor, Rsense2, serves as the current sampling resistor, with one end connected to the output of the current sampling circuit and the other end grounded. When the real-time charging current flows through it, a voltage proportional to the current is generated, used for current sampling. The input of the A / D module is connected between Rsense2 and the power stage output. Its function is to convert the sampled analog current-voltage signal Ibat_sense2 into a digital signal and send it to the logic module for processing. The logic module receives the sampled digital signal from the A / D module and the communication control signal from the MCU, and is the digital control core of the entire constant current loop. Based on the communication status, it outputs a digital signal corresponding to the reference voltage. The input of the first D / A module is connected to the output of the logic module. Its function is to convert the digital signal output by the logic module into an analog voltage and send it to the inverting input of the first operational amplifier U1. The non-inverting input of the first operational amplifier U1 is connected to the voltage corresponding to the sampled current signal Ibat_sense2, and the inverting input of the first operational amplifier U1 is connected to the reference voltage output by the first D / A module. By comparing the two voltages, a control signal is output to the first diode D1. One end of the second bias current is connected to the power stage output terminal, and the other end is grounded, providing a stable bias for the power stage and ensuring the linearity and stability of the loop control. The anode of the first diode D1 is connected to the output terminal of the first operational amplifier U1, and the cathode of the first diode D1 is connected between the power stage output terminal and I3, controlling whether the constant current loop signal is applied to the power stage.

[0064] When the wireless charging receiver needs to communicate (Module=1), it performs two key operations: 1. The logic module outputs a constant voltage reference voltage Ibat_cv_ref.

[0065] The A / D module acquires the sampling voltage corresponding to the charging current Ibat_sense2 on R2 before communication and converts it into a digital signal, which is then sent to the logic module. Based on the MCU's communication instructions and the sampling voltage corresponding to the sampled charging current Ibat_sense2, the logic module generates a constant voltage reference voltage digital signal for the constant voltage communication stage. The first D / A module converts this constant voltage reference voltage digital signal into an analog voltage Ibat_cv_ref and sends it to the inverting input of the first comparator. The first comparator compares the real-time sampling voltage of R2 with Ibat_cv_ref and outputs a control signal that acts on the power stage through the first diode D1, stabilizing the charging current at the value corresponding to Ibat_cv_ref.

[0066] 2. Control the disconnection of the circuit between the output terminal of the constant voltage loop and the control terminal of the power stage.

[0067] Stable constant current characteristics will block the transmission of current pulses from loads such as mobile phone screens to the VRECT side, thus avoiding interference with the communication modulation current Imod.

[0068] The workflow resumes after communication stops (Module=0), following the normal charging mode: 1. Restore the circuit path from the constant voltage loop output terminal to the power stage control terminal.

[0069] 2. The first output terminal of the logic module outputs a constant current reference voltage Ibat_cc_ref.

[0070] The MCU sends a stop communication command to the logic module, and the logic module switches the output of the constant current reference voltage digital signal for the constant current charging stage.

[0071] The first D / A module converts the constant current reference voltage digital signal into an analog voltage Ibat_cc_ref (corresponding to the set maximum charging current value) and sends it to the inverting input of the first comparator.

[0072] The first comparator compares the sampled voltage corresponding to the charging current Ibat_sense2 with Ibat_cc_ref, and controls the power stage to limit the charging current to within the maximum value, ensuring safe charging of the battery.

[0073] In one embodiment, such as Figure 10 The constant voltage circuit includes: a fourth diode D4, a fourth operational amplifier U4, a second D / A module, a fifth resistor Rfb5, and a sixth resistor Rfb6; One end of the fifth resistor Rfb5 is connected to the output terminal of the power stage; the other end of the fifth resistor Rfb5 is connected to one end of the sixth resistor Rfb6, and the other end of the sixth resistor Rfb6 is grounded. The non-inverting input terminal of the fourth operational amplifier U4 is connected between the fifth resistor Rfb5 and the sixth resistor Rfb6; The inverting input terminal of the fourth operational amplifier U4 is connected to the second output terminal of the logic module through the second D / A module; The output terminal of the fourth operational amplifier U4 is connected to the anode of the fourth diode D4, and the cathode of the fourth diode D4 is connected between the control terminal of the power stage and the second bias current. When the wireless charging receiver needs to communicate, the MCU controls the second output terminal of the logic module to output a digital signal corresponding to the adjusted voltage value, and controls the first output terminal of the logic module to output a digital signal corresponding to the constant voltage reference voltage Ibat_cv_ref. When the wireless charging receiver stops communicating, the MCU controls the second output terminal of the logic module to output a digital signal corresponding to the set voltage value, and controls the first output terminal of the logic module to output a digital signal corresponding to the constant current reference voltage Ibat_cc_ref. The set voltage value is the voltage after the battery is fully charged and divided by the sixth resistor Rfb6. The adjusted voltage value is higher than the set voltage value.

[0074] When the wireless charging receiver needs to communicate (Module=1), it performs two key operations: 1. The logic module outputs a constant voltage reference voltage Ibat_cv_ref.

[0075] The A / D module acquires the charging current sampling voltage across R2 before communication and converts it into a digital signal, which is then sent to the logic module. Based on the sampled digital signal and the MCU's communication instructions, the logic module generates a constant voltage reference voltage digital signal corresponding to the constant voltage reference voltage Ibat_cv_ref. The first D / A module converts the constant voltage reference voltage digital signal into an analog voltage Ibat_cv_ref and sends it to the inverting input of the first comparator. The first comparator compares the real-time sampling voltage of R2 with Ibat_cv_ref and outputs a control signal that acts on the power stage through the first diode D1, stabilizing the charging current at the value corresponding to Ibat_cv_ref.

[0076] Stable constant current characteristics will block the current pulses from the mobile phone screen and other loads from being transmitted to the VRECT side, thus avoiding interference with the communication modulation current Imod.

[0077] 2. The second output terminal of the control logic module outputs the digital signal corresponding to the adjusted voltage value, and the second D / A module converts the digital signal corresponding to the adjusted voltage value into the analog signal corresponding to the adjusted voltage value.

[0078] In this embodiment, the set voltage value corresponds to the voltage division of a fully charged normal battery in the sixth resistor Rfb6. With the voltage of a fully charged normal battery being 4.2V, the set voltage value = 4.2V × k, k = Rfb4 / (Rfb3 + Rfb4)). The adjusted voltage value is slightly higher than the set voltage value, for example, 5%. At this time, the voltage of a fully charged normal battery is 4.2V, so the adjusted voltage value = 4.2V × 1.05 × k, k = Rfb4 / (Rfb3 + Rfb4).

[0079] Since the non-inverting input of the fourth operational amplifier U4 is connected between the fifth resistor Rfb5 and the sixth resistor Rfb6, its voltage is the voltage division of the sixth resistor Rfb6. However, the voltage at the inverting input of the fourth operational amplifier U4 is higher than the voltage division, so the output of the fourth operational amplifier U4 is 0, and the fourth diode D4 is cut off, thereby disconnecting the circuit between the output of the constant voltage loop and the control terminal of the power stage.

[0080] The workflow resumes after communication stops (Module=0), following the normal charging mode: 1. The second output terminal of the control logic module outputs a digital signal corresponding to the set voltage value, and the second D / A module converts the digital signal corresponding to the set voltage value into an analog signal corresponding to the set voltage value.

[0081] Since the non-inverting input of the fourth operational amplifier U4 is connected between the fifth resistor Rfb5 and the sixth resistor Rfb6, its voltage value is the voltage division of the sixth resistor Rfb6. The voltage at the inverting input of the fourth operational amplifier U4 is the voltage division of the sixth resistor Rfb6. Therefore, the output of the fourth operational amplifier U4 is 1, and the fourth diode D4 is turned on, thereby connecting the circuit between the output of the constant voltage loop and the control terminal of the power stage.

[0082] 2. The first output terminal of the logic module outputs the digital signal of the constant current reference voltage corresponding to the constant current reference voltage Ibat_cc_ref.

[0083] The MCU sends a stop communication command to the logic module, and the logic module switches the output of the constant current reference voltage digital signal for the constant current charging stage.

[0084] The first D / A module converts the constant current reference voltage digital signal into an analog voltage Ibat_cc_ref (corresponding to the set maximum charging current value) and sends it to the inverting input of the first comparator.

[0085] The first comparator compares the real-time sampled voltage with Ibat_cc_ref, and controls the power stage to limit the charging current to within the maximum value, ensuring safe charging of the battery.

[0086] It is worth noting that in this disclosure, the power stage can be a PMOS transistor or an NMOS transistor, or a linear charging structure designed with power devices such as transistors or GaN.

[0087] It is worth noting that the scheme in this disclosure can be used as long as there is a constant current loop and a constant voltage loop control, such as: linear charging structure, buck type, boost type, buck-boost type, and switched capacitor type charging structure.

[0088] This application provides a battery charging control circuit, a wireless charging receiver, and a wireless charging device for a wireless charging receiver. By combining the constant voltage loop and constant current loop of traditional battery charging control with the communication signal of the wireless charging receiver, the constant voltage loop is disconnected during communication, and the charging voltage target of the constant current loop is adjusted to the reference voltage corresponding to the charging current during communication in the constant voltage charging phase. This reduces communication interference and improves the stability of wireless charging for mobile phones and other electronic products.

[0089] This disclosure also provides a wireless charging receiver, which includes: a receiver coil, a resonant capacitor, a synchronous rectifier, an ASK modulation circuit, and a battery charging control circuit as described in any of the above embodiments, connected in series.

[0090] This disclosure also provides a wireless charging device, which includes: a wireless charging transmitter and a wireless charging receiver as described in the above embodiments.

[0091] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0092] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A battery charging control circuit for a wireless charging receiver, characterized in that, The circuit includes: Power stage, MCU, constant current loop for battery charging, and constant voltage loop for battery charging; The input terminal of the power stage is connected to the voltage after wireless charging rectification; The output terminal of the power stage is connected to the load to provide charging voltage to the load; The control terminal of the power stage is connected to the output terminals of the constant current loop and the constant voltage loop, respectively. The first input terminal of the constant voltage loop is connected to the output terminal of the power stage, and the second input terminal of the constant voltage loop is connected to the internal reference voltage signal; The first input terminal of the constant current loop is connected to the current sampling output terminal of the power stage, and the second input terminal of the constant current loop can be selectively connected to a constant voltage reference voltage and a constant current reference voltage; the constant voltage reference voltage is the reference voltage corresponding to the magnitude of the charging current during the constant voltage charging phase; the constant current reference voltage is the reference voltage corresponding to the magnitude of the charging current during the constant current charging phase. The MCU is connected to the constant current loop and the constant voltage loop respectively; When the wireless charging receiver needs to communicate, the MCU controls the circuit between the output terminal of the constant voltage loop and the control terminal of the power stage to disconnect, and controls the reference voltage of the second input terminal of the constant current loop to switch to a constant voltage reference voltage; when the wireless charging receiver stops communicating, the MCU controls the circuit between the output terminal of the constant voltage loop and the control terminal of the power stage to connect, and controls the reference voltage of the second input terminal of the constant current loop to switch to a constant current reference voltage.

2. The circuit according to claim 1, characterized in that, The constant current reference voltage is greater than the constant voltage reference voltage, and the constant voltage reference voltage gradually decreases during the constant voltage charging phase.

3. The circuit according to claim 1, characterized in that, The constant current loop includes: a first operational amplifier and a first diode; The first input terminal of the first operational amplifier is connected to the current signal collected by the current sampling output terminal of the power stage; The second input terminal of the first operational amplifier can be selectively connected to a constant voltage reference voltage and a constant current reference voltage; The output terminal of the first operational amplifier is connected to the anode of the first diode, and the cathode of the first diode is connected to the control terminal of the power stage; The MCU is connected to the selection switch control terminal connected to the second input terminal of the first operational amplifier. When the wireless charging receiver needs to communicate, the MCU controls the reference voltage of the second input terminal of the first operational amplifier to switch to a constant voltage reference voltage. When the wireless charging receiver stops communicating, the MCU controls the circuit between the output terminal of the constant voltage loop and the control terminal of the power stage to switch the reference voltage of the second input terminal of the first operational amplifier to a constant current reference voltage.

4. The circuit according to claim 3, characterized in that, The constant current loop further includes: a reference voltage selector, a sample and hold module, a first sampling resistor, an inverter, and a first bias current; One end of the first sampling resistor is connected to the current sampling circuit, and the other end of the first sampling resistor is grounded; The non-inverting input of the first operational amplifier is connected between the first sampling resistor and the current sampling circuit; The first input terminal of the reference voltage selector is connected between the first sampling resistor and the current sampling circuit through a sample-and-hold module; the sample-and-hold module samples the voltage corresponding to the charging current sampling signal before communication and holds it as the constant voltage reference voltage; The second input terminal of the reference voltage selector is connected to a constant current reference voltage. The output of the reference voltage selector is connected to the inverting input of the first operational amplifier; The control terminal of the power stage is grounded through a first bias current; The cathode of the first diode is connected between the control terminal of the power stage and the first bias current; The MCU is connected to the control terminal of the reference voltage selector through the inverter. When the wireless charging receiver needs to communicate, the MCU controls the constant voltage loop to stop working and controls the circuit between the first input terminal and the output terminal of the reference voltage selector to be connected. When the wireless charging receiver stops communicating, the MCU controls the constant voltage loop to resume working and controls the circuit between the second input terminal and the output terminal of the reference voltage selector to be connected.

5. The circuit according to claim 1, characterized in that, The constant voltage loop includes: a second operational amplifier, a second diode, a first resistor, and a second resistor; One end of the first resistor is connected to the output terminal of the power stage; the other end of the first resistor is connected to one end of the second resistor, and the other end of the second resistor is grounded. The first input terminal of the second operational amplifier is connected between the first resistor and the second resistor; The second input terminal of the second operational amplifier is connected to an internal reference voltage signal; The output terminal of the second operational amplifier is connected to the anode of the second diode, and the cathode of the second diode is connected between the control terminal of the power stage and the first bias current. The MCU is connected to the enable control terminal of the second operational amplifier via an inverter. When the wireless charging receiver needs to communicate, the MCU controls the second operational amplifier to stop working and controls the circuit between the first input terminal and the output terminal of the reference voltage selector to be turned on. When the wireless charging receiver stops communicating, the MCU controls the second operational amplifier to resume working and controls the circuit between the second input terminal and the output terminal of the reference voltage selector to be turned on.

6. The circuit according to claim 1, characterized in that, The constant voltage loop includes: a third operational amplifier, a third diode, a third resistor, a fourth resistor, and a switch; One end of the third resistor is connected to the output terminal of the power stage; the other end of the third resistor is connected to one end of the fourth resistor, and the other end of the fourth resistor is grounded. The first input terminal of the third operational amplifier is connected between the third resistor and the fourth resistor; The second input terminal of the third operational amplifier is connected to an internal reference voltage signal; The output terminal of the third operational amplifier is connected to the anode of the third diode via a switch, and the cathode of the third diode is connected between the control terminal of the power stage and the first bias current. The MCU is connected to the switch control terminal. When the wireless charging receiver needs to communicate, the MCU controls the switch to open and controls the circuit between the first input terminal and the output terminal of the reference voltage selector to be connected. When the wireless charging receiver stops communicating, the MCU controls the switch to open and controls the circuit between the second input terminal and the output terminal of the reference voltage selector to be connected.

7. The circuit according to claim 3, characterized in that, The constant current circuit includes: an A / D module, a logic module, a first D / A module, a second sampling resistor, and a second bias current; One end of the second sampling resistor is connected to the output terminal of the current sampling circuit, and the other end of the second sampling resistor is grounded; The non-inverting input of the first operational amplifier is connected between the second sampling resistor and the output of the power stage; One end of the A / D module is connected between the second sampling resistor and the output of the current sampling circuit; The other end of the A / D module is connected to the first input terminal of the logic module, the MCU is connected to the second input terminal of the logic module, and the first output terminal of the logic module is connected to the inverting input terminal of the first operational amplifier through the first D / A module; The output terminal of the power stage is grounded through the two bias currents; The output terminal of the first operational amplifier is connected to the anode of the first diode, and the cathode of the first diode is connected between the output terminal of the power stage and the second bias current. When the wireless charging receiver needs to communicate, the MCU controls the first output terminal of the logic module to output the constant voltage reference voltage digital signal corresponding to the constant voltage reference voltage; when the wireless charging receiver stops communicating, the MCU controls the first output terminal of the logic module to output the constant current reference voltage digital signal corresponding to the constant current reference voltage.

8. The circuit according to claim 1, characterized in that, The constant voltage circuit includes: a fourth diode, a fourth operational amplifier, a second D / A module, a fifth resistor, and a sixth resistor; One end of the fifth resistor is connected to the output terminal of the power stage; the other end of the fifth resistor is connected to one end of the sixth resistor, and the other end of the sixth resistor is grounded. The first input terminal of the fourth operational amplifier is connected between the fifth resistor and the sixth resistor; The second input terminal of the fourth operational amplifier is connected to the second output terminal of the logic module through the second D / A module; The output terminal of the fourth operational amplifier is connected to the anode of the fourth diode, and the cathode of the fourth diode is connected between the control terminal of the power stage and the second bias current. When the wireless charging receiver needs to communicate, the MCU controls the second output terminal of the logic module to output a digital signal corresponding to the adjusted voltage value, and controls the first output terminal of the logic module to output a constant voltage reference voltage digital signal corresponding to the constant voltage reference voltage. When the wireless charging receiver stops communicating, the MCU controls the second output terminal of the logic module to output a digital signal corresponding to the set voltage value, and controls the first output terminal of the logic module to output a constant current reference voltage digital signal corresponding to the constant current reference voltage. The set voltage value is the voltage after the battery is fully charged and divided by the sixth resistor. The adjusted voltage value is higher than the set voltage value.

9. A wireless charging receiver, characterized in that, The wireless charging receiver includes: a receiver coil, a resonant capacitor, a synchronous rectifier, an ASK modulation circuit, and a battery charging control circuit as described in any one of claims 1-8, connected in series.

10. A wireless charging device, characterized in that, The wireless charging device includes: a wireless charging transmitter and a wireless charging receiver as described in claim 9.

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