H-bridge motor driving chip based on segmented current driving technology

Abstract

The application discloses an H-bridge motor driving chip based on a segmented current driving technology, and belongs to the technical field of H-bridge motor driving chips.The H-bridge motor driving chip comprises an H-bridge output stage circuit, a high-side driving circuit, a low-side driving circuit and a logic control part.The H-bridge output stage circuit is composed of four LDMOS and bears high voltage and large current output of a power stage power supply.The high-side driving circuit converts high-side tube logic control signals from the logic control part into switch tube driving signals with certain driving capacity in a high-side tube power supply domain.The low-side driving circuit converts low-side tube logic control signals from the logic control part into switch tube driving signals with certain driving capacity in a low-side tube power supply domain.The logic control part generates logic control signals for controlling four switch tubes of the H-bridge according to input signals of PWM and DIR pins, as well as detection signals of a state detection circuit and a protection circuit in the internal driving circuit.

Description

Technical Field

[0001] This invention relates to an H-bridge motor driver chip, and more particularly to an H-bridge motor driver chip based on segmented current drive technology, belonging to the technical field of H-bridge motor driver chips. Background Technology

[0002] The H-bridge can precisely control the magnitude and direction of motor current, and is a simple, reliable, and flexible motor drive method. It can drive devices such as solenoid valves, rearview mirrors, windshield wipers, and door locks in automobiles, and is widely used in the automotive industry. The reliability of automotive chips is directly related to people's personal safety; therefore, automotive-grade chip standards have extremely high requirements for electromagnetic compatibility (EMC).

[0003] Compared to traditional gasoline vehicles, new energy vehicles mainly convert electrical energy into mechanical energy, resulting in lower travel costs and aligning with the concept of green travel. Consequently, new energy vehicles are equipped with a greater number of electronic devices, such as motors and their drive chips. However, this also brings greater electromagnetic interference (EMI). The rapid development of new energy vehicles and the increasingly serious EMI problem in vehicles have brought both tremendous opportunities and challenges to the development of H-bridge motor drive chips. Therefore, it is necessary to conduct research on high-reliability H-bridge motor drive chips for automotive applications.

[0004] In the application scenarios of automotive electronics, the requirements have changed, and reliability has become the primary requirement for chips. Automotive-grade chips have a lower maximum switching frequency than consumer-grade chips, mostly around 20 kHz. There are also many restrictions on the rate of change of output voltage and current or edge time. These restrictions are mainly to ensure reliability and meet electromagnetic compatibility requirements, but they also lead to increased switching losses. This problem is very fatal for consumer electronics. To solve this problem, an H-bridge motor driver chip based on segmented current drive technology is designed. Summary of the Invention

[0005] The main objective of this invention is to provide an H-bridge motor driver chip based on segmented current drive technology.

[0006] The objective of this invention can be achieved by adopting the following technical solution:

[0007] The H-bridge motor driver chip based on segmented current drive technology includes the H-bridge output stage circuit: composed of four LDMOS, which is responsible for the high voltage and high current output of the power stage power supply.

[0008] High-side drive circuit: converts the logic control signal from the high-side transistor in the logic control section into a switching transistor drive signal with a certain driving capability in the power domain of the high-side transistor.

[0009] Low-side drive circuit: converts the logic control signals of the low-side transistors from the logic control section into switching transistor drive signals with a certain driving capability in the power domain of the low-side transistors.

[0010] Logic control: Based on the input signals of the PWM and DIR pins, as well as the detection signals of the state detection circuit and protection circuit in the internal drive circuit, logic control signals are generated to control the four switching transistors of the H-bridge.

[0011] Over-temperature protection module: generates over-temperature current limiting signal and over-temperature shutdown signal. The over-temperature shutdown signal has hysteresis characteristics and generates a current with a positive temperature coefficient to reduce the over-current threshold of the over-current protection module at high temperatures.

[0012] Current sampling module: This module samples the output current of the H-bridge and generates a value similar to the output current. Proportional sampling current from Pin output to external resistor superior;

[0013] Overcurrent protection module: Monitors the voltage of the CF pin. When the CF pin level is high, it outputs an overcurrent protection signal, indicating that the H-bridge output current is overcurrent, and controls the H-bridge to enter freewheeling mode. The current limiting threshold will decrease as the temperature rises.

[0014] Current mirror bias circuit: mirrors the bias current input at the IB pin to each sub-module as bias.

[0015] High-side floating ground generation circuit: Provides the high-side floating ground voltage required by HS. It receives the sink current from the high-side drive circuit and generates the Miller reference voltage. .

[0016] In this embodiment, the current sampling module includes a SenseFET and a low-side switch with a size ratio of 1:K. A four-stage operational amplifier negative feedback loop clamps the VOUT and VSENSE voltages to a virtual short, thereby obtaining the sampling current ISENSE, where ISENSE: IOUT = (W / L)SenseFET / (W / L)LS = 1:K.

[0017] In the output section, the sampling current is mirrored as ICF at a 1:1 ratio through the current mirror formed by M20 and M21. After passing through a gain enhancement structure to increase the output resistance, it is output from the CF pin to the external resistor RCF, generating a sampling voltage VCF that is proportional to the output current.

[0018] The M21 current mirror is located in the VHGND to VS voltage domain, so the sampling voltage VCF can rise above the VLDO voltage;

[0019] The relationship between the sampling voltage VCF and the output current IOUT is shown in the following equation;

[0020] ;

[0021] The current sampling operational amplifier uses a two-stage cascode structure with PMOS as the input pair transistors.

[0022] A feedback loop is formed from the negative input terminal of the op-amp to M24, M20, and M19.

[0023] In this embodiment, the overcurrent protection module includes a VCF sampling circuit, a current limiting threshold adjustment circuit, and an overcurrent detection comparator circuit. The sampling current flows through the external resistor RCF, and the sampling voltage VCF generated at the CF pin is proportional to the output current.

[0024] By setting an overvoltage threshold VCFTH for VCF, the overcurrent detection of output current IOUT can be achieved.

[0025] In this embodiment, the VCF sampling circuit samples the voltage VCF at the CF pin through a resistor network;

[0026] The resistance values ​​of R0-R2 in the resistor network need to be as large as possible to reduce the impact of current shunting in this branch on the ICF.

[0027] Ignoring the current shunting of the resistor network, the voltage VA at point A and the voltage VB at point B obtained from the sampling can be calculated using equations (4.22) and (4.23), respectively.

[0028]

[0029]

[0030] Hysteresis is achieved by connecting either node A or B to the negative input of comparator COMP1 using a two-way selector.

[0031] The comparator's output signal COMP serves as the control signal for the two-way selector;

[0032] When COMP=0, point A is connected to the negative input of comparator COMP1, corresponding to a lower VCF threshold voltage. ;

[0033] When COMP=1, point B is connected to the negative input of comparator COMP1, corresponding to a higher... Threshold voltage ;

[0034] The current limiting threshold adjustment circuit adjusts the external bandgap reference voltage. After passing through a buffer and resistor with current output capability It is then connected to the positive input of comparator COMP1. Simultaneously, the positive input of COMP1 is also connected to the branch that generates IPTAT from the over-temperature protection circuit.

[0035] Beneficial technical effects of the present invention:

[0036] The H-bridge motor driver chip based on segmented current drive technology provided by the present invention includes an H-bridge output stage circuit: composed of four LDMOS, which undertakes the high voltage and high current output of the power stage power supply;

[0037] High-side drive circuit: converts the logic control signal from the high-side transistor in the logic control section into a switching transistor drive signal with a certain driving capability in the power domain of the high-side transistor.

[0038] Low-side drive circuit: converts the logic control signals of the low-side transistors from the logic control section into switching transistor drive signals with a certain driving capability in the power domain of the low-side transistors.

[0039] Logic control: Based on the input signals of the PWM and DIR pins, as well as the detection signals of the state detection circuit and protection circuit in the internal drive circuit, logic control signals are generated to control the four switching transistors of the H-bridge.

[0040] Over-temperature protection module: generates over-temperature current limiting signal and over-temperature shutdown signal. The over-temperature shutdown signal has hysteresis characteristics and generates a current with a positive temperature coefficient to reduce the over-current threshold of the over-current protection module at high temperatures.

[0041] Current sampling module: This module samples the output current of the H-bridge and generates a value similar to the output current. Proportional sampling current from CF Pin output to external resistor superior;

[0042] Overcurrent protection module: Monitors the voltage of the CF pin. When the CF pin level is high, it outputs an overcurrent protection signal, indicating that the H-bridge output current is overcurrent, and controls the H-bridge to enter freewheeling mode. The current limiting threshold will decrease as the temperature rises.

[0043] Current mirror bias circuit: mirrors the bias current input at the IB pin to each sub-module as bias.

[0044] High-side floating ground generation circuit: Provides the high-side floating ground voltage required by HS. It receives the sink current from the high-side drive circuit and generates the Miller reference voltage. . Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the overall architecture of an H-bridge motor driver chip according to a preferred embodiment of the H-bridge motor driver chip based on segmented current drive technology of the present invention.

[0046] Figure 2 This is a circuit diagram of an overcurrent detection circuit according to a preferred embodiment of an H-bridge motor driver chip based on segmented current drive technology of the present invention;

[0047] Figure 3 A figure is shown for a preferred embodiment of an H-bridge motor driver chip based on segmented current drive technology according to the present invention;

[0048] Figure 4 This is a schematic diagram of an overcurrent detection circuit according to a preferred embodiment of an H-bridge motor driver chip based on segmented current drive technology of the present invention.

[0049] Figure 5 This is an overcurrent threshold diagram of a preferred embodiment of an H-bridge motor driver chip based on segmented current drive technology according to the present invention. Detailed Implementation

[0050] To enable those skilled in the art to understand the technical solution of the present invention more clearly, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0051] like Figures 1-5 As shown in the figure, the H-bridge motor driver chip based on segmented current drive technology provided in this embodiment has the following overall architecture. The core components of the chip include the H-bridge output stage circuit, drive circuit, logic control circuit, and protection circuit. In addition, there is a high-side floating ground generation circuit and a current mirror bias circuit. The chip power supply is provided by an external LDO, and the bias current is also provided by an external current source, which is mirrored to each module as the bias current through the current mirror bias circuit. The functions of each key sub-module in the overall architecture of the H-bridge motor driver chip are described below.

[0052] H-bridge output stage circuit: Composed of four LDMOS, it undertakes the high voltage and high current output of the power stage.

[0053] High-side drive circuit: converts the logic control signal from the high-side transistor in the logic control section into a switching transistor drive signal with a certain driving capability in the power domain of the high-side transistor.

[0054] Low-side drive circuit: Converts the logic control signals of the low-side transistors from the logic control section into switching transistor drive signals with a certain driving capability in the power domain of the low-side transistors.

[0055] Logic control: Based on the input signals of the PWM and DIR pins, as well as the detection signals of the state detection circuit and protection circuit in the internal drive circuit, logic control signals are generated to control the four switching transistors of the H-bridge.

[0056] Over-temperature protection: Generates an over-temperature current limiting signal and an over-temperature shutdown signal. The over-temperature shutdown signal has hysteresis characteristics. In addition, it generates a current with a positive temperature coefficient to reduce the over-current threshold of the over-current protection module at high temperatures.

[0057] Current sampling: This module samples the output current of the H-bridge and generates a sampling current ICF that is proportional to the output current IOUT, which is output from the CF pin to the external resistor RCF.

[0058] Overcurrent protection: Monitors the voltage at the CF pin. When the CF pin level is high, an overcurrent protection signal is output, indicating that the H-bridge output current is too high, and the H-bridge is controlled to enter freewheeling mode. The current limiting threshold decreases as the temperature increases.

[0059] Current mirror bias circuit: The bias current input at the IB pin is mirrored to each sub-module as bias.

[0060] High-side floating ground generation circuit: Provides the high-side floating ground voltage required by HS. It receives the sink current from the high-side drive circuit and generates the Miller reference voltage. .

[0061] H-bridge motor driver chip pin description

[0062] Based on the module division and analysis in the overall architecture diagram, the number of pins of the H-bridge motor driver chip and the functional definition of each pin were determined. The pin number, name, input / output type, and functional description are shown in Table 1.

[0063] Table 1 Pin Descriptions of H-Bridge Motor Driver Chips

[0064]

[0065] The relative positions of each pin can be determined based on the number and number of the pins.

[0066] In the sampling section, the size ratio of the SenseFET to the low-side switch is 1:K. A four-stage op-amp negative feedback loop clamps the VOUT and VSENSE voltages into a "virtual short," thus obtaining the sampling current ISENSE, where ISENSE: IOUT = (W / L)SenseFET / (W / L)LS = 1 : K. In the output section, a current mirror composed of M20 and M21 mirrors the sampling current 1:1 to ICF. After passing through a gain enhancement structure to increase the output resistance, it is output from the CF pin to the external resistor RCF, generating a sampling voltage VCF proportional to the output current. Since the M21 current mirror is located in the VHGND to VS voltage domain, the sampling voltage VCF can rise above the VLDO voltage. The relationship between the sampling voltage VCF and the output current IOUT is shown in equation (4.15). In this design, K=5882 is used.

[0067]

[0068] Considering that the input current sampling op-amp has a very small VOUT when the low-side transistor is turned on, the current sampling op-amp adopts a two-stage cascode structure with PMOS as the input pair transistor to achieve sampling of the low VOUT and increase the loop gain.

[0069] A feedback loop is formed from the negative input terminal of the operational amplifier to M24, M20, and M19, therefore, its loop stability needs to be analyzed. The equivalent circuit diagram of the current sampling circuit is shown below. These are the transconductances from the first to the fourth stages of the loop. These represent the output impedances from the first to the fourth stage of the loop, RON and SenseFET are the on-resistances of the SenseFET, and CC and RC are the capacitor and resistor for RC Miller compensation, respectively.

[0070] Under heavy load, the increase in transconductance Gm4 leads to an increase in loop gain, causing the unity gain frequency (UGF) of the loop gain to shift to higher frequencies. This may cause high-frequency poles to enter the UGF, resulting in stability issues. To ensure the stability of the current sampling circuit, CC and RC are introduced for RC Miller compensation. The zeros generated by RC Miller compensation are used to cancel the output poles of the second-stage op-amp. The zero frequencies generated by RC Miller compensation and the output pole frequencies of the second-stage op-amp are shown in equations (4.16) and (4.17), respectively.

[0071]

[0072]

[0073] To make the two equal and cancel each other out, it is only necessary to satisfy equation (4.18).

[0074]

[0075] Of the remaining poles, RO3 can be expressed as equation (4.19).

[0076]

[0077] In the formula, gm20 is the transconductance of M20, and it can be seen that the resistance of RO3 is very low. RON,SenseFET is the on-resistance of the SenseFET operating in the linear region, and its resistance is also very low. Therefore, the remaining dominant poles are still outside the UGF. The loop gain T(s) of the compensated current sampling circuit can be determined by equation (4.20), and correspondingly, the UGF can be determined by equation (4.21).

[0078]

[0079]

[0080] The overcurrent detection circuit in this design can be divided into a VCF sampling circuit, a current limiting threshold adjustment circuit, and an overcurrent detection comparator circuit. According to equation (4.15), the sampling current flows through the external resistor RCF, and the sampling voltage VCF generated at the CF pin is proportional to the output current. Therefore, an overvoltage threshold VCFTH can be set for VCF to determine if the output current IOUT is overcurrent. In this design, the target value of VCFTH is set to approximately 4.5V.

[0081] The VCF sampling circuit samples the voltage VCF at the CF pin through a resistor network. The resistance value needs to be as large as possible to reduce the impact of current shunting in this branch on the ICF. Ignoring the current shunting in the resistor network, the voltage VA at point A and the voltage VB at point B obtained from the sampling can be calculated using equations (4.22) and (4.23), respectively.

[0082]

[0083]

[0084] A hysteresis function is achieved by connecting either node A or B to the negative input of comparator COMP1 using a two-way selector. The comparator's output signal COMP serves as the control signal for the two-way selector. When COMP=0, point A is connected to the negative input of comparator COMP1, corresponding to a lower VCF threshold voltage. When COMP=1, point B is connected to the negative input of comparator COMP1, corresponding to a higher VCF threshold voltage. .

[0085] The current limiting threshold adjustment circuit connects the external bandgap reference voltage VBG to the positive input of comparator COMP1 via a buffer with current output capability and resistor R3. Simultaneously, the positive input of COMP1 is also connected to the branch of the over-temperature protection circuit that generates IPTAT. Thus, the input voltage VREF,CL at the positive input of COMP1 decreases as IPTAT increases, and the slope of this decrease is equal to the resistance value of R3, as shown in equation (4.24).

[0086]

[0087] Combining equations (4.23) and (4.24), the switching voltage of the overcurrent detection comparator when COMP=1 can be obtained. for:

[0088]

[0089] Combining equations (4.22) and (4.24), the switching voltage of the overcurrent detection comparator when COMP=0 can be obtained. for:

[0090]

[0091] In the formula, IPTAT comes from the over-temperature protection circuit and increases with increasing temperature. Therefore, the threshold voltage VCFTH at the CL signal transition will decrease with increasing temperature. Ultimately, this enables the chip's overcurrent detection threshold current IL to decrease with increasing temperature. It is important to note that R3 in this module must be matched with the two resistors in the over-temperature protection circuit to reduce the error caused by variations in R3's resistance value due to process angles and temperature, thereby improving the circuit's robustness.

[0092] The above description is merely a further embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope disclosed in the present invention, based on the technical solution and concept of the present invention, shall fall within the scope of protection of the present invention.

Claims

1. An H-bridge motor driver chip based on segmented current drive technology, characterized in that: Including the H-bridge output stage circuit: composed of four LDMOS, which handles the high voltage and high current output of the power stage; High-side drive circuit: converts the logic control signal from the high-side transistor in the logic control section into a switching transistor drive signal with a certain driving capability in the power domain of the high-side transistor. Low-side drive circuit: converts the logic control signals of the low-side transistors from the logic control section into switching transistor drive signals with a certain driving capability in the power domain of the low-side transistors. Logic control: Based on the input signals of the PWM and DIR pins, as well as the detection signals of the state detection circuit and protection circuit in the internal drive circuit, logic control signals are generated to control the four switching transistors of the H-bridge. Over-temperature protection module: generates over-temperature current limiting signal and over-temperature shutdown signal. The over-temperature shutdown signal has hysteresis characteristics and generates a current with a positive temperature coefficient to reduce the over-current threshold of the over-current protection module at high temperatures. Current sampling module: This module samples the output current of the H-bridge and generates a value equal to the output current I. OUT Proportional sampling current Output from CF pin to external resistor superior; Overcurrent protection module: Monitors the voltage of the CF pin. When the CF pin level is high, it outputs an overcurrent protection signal, indicating that the H-bridge output current is overcurrent, and controls the H-bridge to enter freewheeling mode. The current limiting threshold will decrease as the temperature rises. Current mirror bias circuit: mirrors the bias current input at the IB pin to each sub-module as bias. High-side floating ground generation circuit: Provides the high-side floating ground voltage required by HS. , It is a power stage power supply that receives sink current from the high-side drive circuit and generates the Miller reference voltage. ; The overcurrent protection module includes a VCF sampling circuit, a current limiting threshold adjustment circuit, and an overcurrent detection comparator circuit. The sampling current flows through the external resistor RCF, and the sampling voltage VCF generated at the CF pin is proportional to the output current. By setting an overvoltage threshold VCFTH for VCF, the overcurrent detection of output current IOUT can be achieved. The current limiting threshold adjustment circuit adjusts the external bandgap reference voltage. After passing through a buffer and resistor with current output capability It is then connected to the positive input of comparator COMP1; at the same time, the positive input of COMP1 is also connected to the branch that generates IPTAT in the over-temperature protection circuit. IPTAT increases with increasing temperature.

2. The H-bridge motor driver chip based on segmented current drive technology according to claim 1, characterized in that: The current sampling module includes a SenseFET, with a size ratio of 1:K to the low-side switch. A four-stage operational amplifier negative feedback loop is used to sample the drain voltage of the low-side switch. Voltage at the drain of the SenseFET The voltage clamp is virtual short, and the sampling current ISENSE is obtained, with ISENSE:IOUT=1:K; In the output section, the sampling current is mirrored as ICF at a 1:1 ratio through the current mirror formed by M20 and M21. After passing through a gain enhancement structure to increase the output resistance, it is output from the CF pin to the external resistor RCF, generating a sampling voltage VCF that is proportional to the output current. The M21 current mirror is located in the VHGND to VS voltage domain, so the sampling voltage VCF can rise above the VLDO analog circuit power supply voltage. The relationship between the sampling voltage VCF and the output current IOUT is shown in the following equation; ； The current sampling operational amplifier uses a two-stage cascode structure with PMOS as the input pair transistors.

3. The H-bridge motor driver chip based on segmented current drive technology according to claim 2, characterized in that: The VCF sampling circuit samples the voltage VCF at the CF pin through a resistor network. The resistance values ​​of R0-R2 in the resistor network need to be as large as possible to reduce the impact of the current shunting of the sampling circuit on the ICF; Ignoring the current shunting of the resistor network, the voltage VA at point A and the voltage VB at point B obtained from the sampling can be calculated using equations (4.22) and (4.23), respectively. ； ； Hysteresis is achieved by connecting either node A or B to the negative input of comparator COMP1 using a two-way selector. The comparator's output signal COMP serves as the control signal for the two-way selector; When COMP=0, point A is connected to the negative input of comparator COMP1, corresponding to a lower VCF threshold voltage. ; When COMP=1, point B is connected to the negative input of comparator COMP1, corresponding to a higher V. CF Threshold voltage .

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