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

Abstract

The invention discloses an H-bridge motor driving chip based on a segmented current driving technology, which belongs to the technical field of H-bridge motor driving chips, and comprises an H-bridge output stage circuit which consists of four LDMOS (laterally diffused metal oxide semiconductor) and is used for bearing high-voltage and large-current output of a power stage power supply, the high-side driving circuit is used for converting a high-side tube logic control signal from the logic control part into a switch tube driving signal with certain driving capability in a high-side tube power supply domain; the low-side driving circuit is used for converting a low-side tube logic control signal from the logic control part into a switch tube driving signal with a certain driving capability in a low-side tube power domain, and logic control is used for converting the switch tube driving signal into a switch tube driving signal with a certain driving capability according to input signals of PWM and DIR pins and detection signals of a state detection circuit and a protection circuit in an internal driving circuit. And a logic control signal for controlling four switching tubes of the H bridge is generated.

Description

Technical Field

[0001] The invention relates to an H-bridge motor driving chip, in particular to 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. Background Art

[0002] The H-bridge can accurately control the magnitude and direction of the motor current. It is a simple, reliable and flexible way to drive the motor. It can drive the solenoid valves, rearview mirrors, wipers, door locks and other devices in the car. It is widely used in the automotive field. The reliability of automotive chips is directly related to people's personal safety, so the automotive-grade chip standards have made extremely high requirements for electromagnetic compatibility (EMC).

[0003] Compared with traditional fuel vehicles, new energy vehicles mainly convert electrical energy into mechanical energy, with lower travel costs, which is in line with the concept of green travel. Therefore, the number of electronic devices installed in new energy vehicles is also greater, such as motors and their driver chips, but this also brings greater electromagnetic interference (EMI). The rapid development of new energy vehicles and the increasingly serious EMI problems in vehicles have brought huge opportunities and challenges to the development of H-bridge motor driver chips. Therefore, it is necessary to conduct research on high-reliability H-bridge motor driver chips for automotive applications.

[0004] In the existing technology, in the application scenario of automotive electronics, the demand has changed, and reliability has become the primary requirement for chips. The maximum switching frequency of automotive-grade chips is lower than that of consumer-grade chips, mostly around 20 kHz, and there are many restrictions on the change rate or edge time of output voltage and current. These restrictions are mainly to ensure reliability and meet electromagnetic compatibility requirements, but they will also bring about the problem of increased switching losses, which is very fatal for consumer electronics. For this reason, an H-bridge motor driver chip based on segmented current drive technology is designed to solve the above problems. Summary of the invention

[0005] The main purpose of the present invention is to provide an H-bridge motor driving chip based on segmented current driving technology.

[0006] The purpose of the present invention can be achieved by adopting the following technical solutions:

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

[0008] High-side drive circuit: converts the high-side tube logic control signal from the logic control part into a switch tube drive signal with a certain driving capability in the high-side tube power domain;

[0009] Low-side drive circuit: converts the low-side tube logic control signal from the logic control part into a switch tube drive signal with a certain driving capability in the low-side tube power domain;

[0010] Logic control: Generates logic control signals for controlling the four switch tubes of the H-bridge according to 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;

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

[0012] Current sampling module: This module samples the output current of the H-bridge and generates a current that is equal to the output current I OUT Proportional sampling current I CF from CF Pin output to external resistor R CF superior;

[0013] Overcurrent protection module: monitors the CF pin voltage. 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 the freewheeling state. The current limiting threshold will become smaller when the temperature rises.

[0014] Current mirror bias circuit: mirrors the bias current input from the IB pin to each submodule as a bias;

[0015] High-side floating ground generation circuit: Provides the high-side floating ground voltage V required by HS HGND =V S -3.3V, receiving the sink current from the high-side driver circuit and generating the Miller reference voltage V MILLER,REF .

[0016] In this embodiment, the current sampling module includes a SenseFET and a low-side switch tube with a size ratio of 1:K. The VOUT and VSENSE voltages are clamped virtually short through a four-stage operational amplifier negative feedback loop to obtain a sampling current ISENSE, and ISENSE: IOUT = (W / L)SenseFET / (W / L)LS = 1:K;

[0017] In the output part, the sampling current is mirrored to ICF by the current mirror formed by M20 and M21, and then output from the CF pin to the external resistor RCF after increasing the output resistance through a gain enhancement structure, generating a sampling voltage VCF proportional to the output current;

[0018] The M21 current mirror is in the VHGND to VS voltage domain, so the sampling voltage VCF can be increased to exceed the VLDO voltage;

[0019] The relationship between the sampling voltage VCF and the output current IOUT is as follows:

[0020]

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

[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] An over-voltage threshold VCFTH is set for VCF to determine whether the output current IOUT is over-current.

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

[0026] The resistance value of the resistor network R0-R2 needs to be as large as possible to reduce the impact of the branch current on ICF;

[0027] Ignoring the shunt of the resistor network, the sampled voltage VA at point A and the voltage VB at point B can be calculated by equations (4.22) and (4.23) respectively.

[0028]

[0029] The A or B node is connected to the negative input terminal of the comparator COMP1 through a two-way selector to achieve the hysteresis function;

[0030] The output signal COMP of the comparator is used as the control signal of the two-way selector;

[0031] When COMP = 0, point A is connected to the negative input of comparator COMP1, corresponding to the lower VCF threshold voltage V CFTH =V CFTH- ;

[0032] When COMP = 1, point B is connected to the negative input of comparator COMP1, corresponding to a higher V CF Threshold voltage VCFTH = V CFTH+ ;

[0033] The current limit threshold adjustment circuit converts the external bandgap reference voltage V BG After passing through a BUFFER with current output capability and resistor R3, it is connected to the positive input terminal of comparator COMP1. At the same time, the positive input terminal of COMP1 is also connected to the branch of the over-temperature protection circuit that generates IPTAT.

[0034] Beneficial technical effects of the present invention:

[0035] The H-bridge motor driving chip based on the segmented current driving technology provided by the present invention comprises an H-bridge output stage circuit: composed of four LDMOS, responsible for the high voltage and high current output of the power stage power supply;

[0036] High-side drive circuit: converts the high-side tube logic control signal from the logic control part into a switch tube drive signal with a certain driving capability in the high-side tube power domain;

[0037] Low-side drive circuit: converts the low-side tube logic control signal from the logic control part into a switch tube drive signal with a certain driving capability in the low-side tube power domain;

[0038] Logic control: Generates logic control signals for controlling the four switch tubes of the H-bridge according to 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;

[0039] Over-temperature protection module: generates over-temperature current limiting signal and over-temperature shutdown signal. The over-temperature shutdown signal has a hysteresis characteristic and generates a current with a positive temperature coefficient to reduce the over-current threshold of the over-current protection module at high temperature.

[0040] Current sampling module: This module samples the output current of the H-bridge and generates a current that is equal to the output current I OUT Proportional sampling current I CF from CF Pin output to external resistor R CF superior;

[0041] Overcurrent protection module: monitors the CF pin voltage. 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 the freewheeling state. The current limiting threshold will become smaller when the temperature rises.

[0042] Current mirror bias circuit: mirrors the bias current input from the IB pin to each submodule as a bias;

[0043] High-side floating ground generation circuit: Provides the high-side floating ground voltage V required by HS HGND =V S-3.3V, receiving the sink current from the high-side driver circuit and generating the Miller reference voltage V MILLER,REF . BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is an overall architecture diagram of an H-bridge motor driver chip according to a preferred embodiment of the H-bridge motor driver chip based on the segmented current driving technology of the present invention;

[0045] Figure 2 An overcurrent detection circuit diagram of a preferred embodiment of an H-bridge motor drive chip based on segmented current drive technology according to the present invention;

[0046] Figure 3 A diagram of a preferred embodiment of an H-bridge motor driving chip based on segmented current driving technology according to the present invention;

[0047] Figure 4 It is a schematic diagram of an overcurrent detection circuit according to a preferred embodiment of an H-bridge motor drive chip based on segmented current drive technology of the present invention;

[0048] Figure 5 This is an overcurrent threshold diagram of a preferred embodiment of an H-bridge motor driving chip based on segmented current driving technology according to the present invention. DETAILED DESCRIPTION

[0049] In order to make the technical solution of the present invention more clear and specific to those skilled in the art, the present invention is further described in detail below in conjunction with embodiments and drawings, but the implementation manner of the present invention is not limited thereto.

[0050] like Figure 1-Figure 5 As shown, the H-bridge motor driver chip based on the segmented current driving technology provided in this embodiment, the overall architecture of the designed H-bridge motor driver chip, the core components of the chip include the H-bridge output stage circuit, the driving circuit, the logic control circuit and the protection circuit, in addition to the high-side floating ground generation circuit and the 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 a 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 as follows.

[0051] H-bridge output stage circuit: It consists of four LDMOS and is responsible for the high voltage and high current output of the power stage power supply.

[0052] High-side drive circuit: converts the high-side tube logic control signal from the logic control part into a switch tube drive signal with a certain driving capability in the high-side tube power domain.

[0053] Low-side drive circuit: converts the low-side tube logic control signal from the logic control part into a switch tube drive signal with a certain driving capability in the low-side tube power domain.

[0054] Logic control: Based on the input signals of the PWM and DIR pins, as well as the detection signals of the status detection circuit and protection circuit in the internal drive circuit, logic control signals are generated to control the four switch tubes of the H-bridge.

[0055] Over-temperature protection: Generates over-temperature current limiting signal and over-temperature shutdown signal. The over-temperature shutdown signal has a hysteresis characteristic. In addition, it will generate a current with a positive temperature coefficient to reduce the over-current threshold of the over-current protection module at high temperature.

[0056] Current sampling: This module samples the output current of the H-bridge and generates a sampling current ICF proportional to the output current IOUT, which is output from the CF pin to the external resistor RCF.

[0057] Overcurrent protection: monitor the CF pin voltage. When the CF pin level is high, an overcurrent protection signal is output, indicating that the H-bridge output current is overcurrent, and the H-bridge is controlled to enter the continuous current state. The current limit threshold will decrease when the temperature rises.

[0058] Current mirror bias circuit: The bias current input from the IB pin is mirrored to each sub-module as a bias.

[0059] High-side floating ground generation circuit: provides the high-side floating ground voltage VHGND = VS-3.3V required by HS, receives the sink current from the high-side drive circuit, and generates the Miller reference voltage V MILLER,REF .

[0060] H-bridge motor driver chip pin description

[0061] According to the division and analysis of the modules in the overall architecture diagram, the number of pins of the H-bridge motor driver chip and the functional definition of each pin are determined. The pin number, name, input and output type and functional description are shown in Table 3.3.

[0062] Table 3.3H-bridge motor driver chip pin description

[0063]

[0064]

[0065] According to the number and number of pins, the relative position of each pin can be determined.

[0066] In the sampling part, the size ratio of SenseFET and low-side switch is 1:K. Through a four-stage op amp negative feedback loop, the VOUT and VSENSE voltages are clamped to "virtually short", thereby obtaining the sampling current ISENSE, and ISENSE: IOUT = (W / L)SenseFET / (W / L)LS = 1:K. In the output part, the sampling current is mirrored 1:1 to ICF through the current mirror formed by M20 and M21, and after a gain enhancement structure increases 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 in the VHGND to VS voltage domain, the sampling voltage VCF can be increased to exceed the VLDO voltage. The relationship between the sampling voltage VCF and the output current IOUT is shown in formula (4.15). In this design, K = 5882.

[0067]

[0068] Considering that the VOUT of the input current sampling amplifier is very small when the low-side tube is turned on, the current sampling amplifier uses PMOS as a two-stage cascode structure for the input pair tube to achieve sampling of low VOUT and increase the loop gain.

[0069] A feedback loop is formed from the negative input terminal of the op amp to M24, M20, and M19, so the loop stability needs to be analyzed. The loop equivalent schematic diagram of the current sampling circuit. Gm1~Gm4 are the transconductances of the first to fourth stages of the loop, RO1~RO3 are the output impedances of the first to fourth stages of the loop, RON,SenseFET is the on-resistance of SenseFET, CC and RC are the capacitor and resistor of RC Miller compensation.

[0070] When overloaded, the transconductance Gm4 increases, causing the loop gain to increase, resulting in the unity gain frequency (UnityGain Frequency, UGF) of the loop gain moving toward high frequency, which may cause the high-frequency pole to enter the UGF, causing stability problems. In order to ensure the stability of the current sampling circuit, CC and RC are introduced for RC Miller compensation, and the zero point generated by RC Miller compensation is used to offset the output pole of the second-stage op amp. The zero point frequency generated under RC Miller compensation and the output pole frequency of the second-stage op amp are shown in Equation (4.16) and Equation (4.17), respectively.

[0071]

[0072] To make the two equal and cancel each other out, we only need to satisfy equation (4.18).

[0073]

[0074] Among the remaining poles, RO3 can be expressed as formula (4.19).

[0075]

[0076] Where 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 SenseFET working in the linear region, and its resistance is also very low, so the remaining main poles are still outside UGF. The loop gain T(s) of the compensated current sampling circuit can be determined by equation (4.20), and correspondingly, UGF can be determined by equation (4.21).

[0077]

[0078] The overcurrent detection circuit of this design can be divided into VCF sampling circuit, current limit threshold adjustment circuit and overcurrent detection comparator circuit. According to formula (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, the overcurrent of the output current IOUT can be determined by setting an overvoltage threshold VCFTH for VCF. This design sets the target value of VCFTH to about 4.5V.

[0079] The VCF sampling circuit samples the voltage VCF of the CF pin through a resistor network. The resistance values ​​of R0~R2 of the resistor network need to be as large as possible to reduce the impact of the shunt of this branch on ICF. Ignoring the shunt of the resistor network, the sampled voltages VA at point A and VB at point B can be calculated by equations (4.22) and (4.23) respectively.

[0080]

[0081] The hysteresis function is realized by connecting the A or B node to the negative input of the comparator COMP1 through a two-way selector. The output signal COMP of the comparator is used as the control signal of the two-way selector. When COMP = 0, point A is connected to the negative input of the comparator COMP1, corresponding to the lower VCF threshold voltage VCFTH = VCFTH-; when COMP = 1, point B is connected to the negative input of the comparator COMP1, corresponding to the higher VCF threshold voltage VCFTH = VCFTH+.

[0082] The current limiting threshold adjustment circuit connects the external bandgap reference voltage VBG to the positive input of the comparator COMP1 through a BUFFER with current output capability and resistor R3. At the same time, the positive input of COMP1 is also connected to the branch that generates IPTAT in the over-temperature protection circuit. In this way, the input voltage VREF,CL at the positive input of COMP1 will decrease as IPTAT increases, and the slope of the decrease is the resistance value of R3, as shown in formula (4.24).

[0083] V REF,CL =V BG -I PTAT R3(4.24)

[0084] Combining equations (4.23) and (4.24), we can get the flip voltage VCFTH+ of the overcurrent detection comparator when COMP = 1:

[0085]

[0086] Combining equations (4.22) and (4.24), we can get the flip voltage VCFTH- of the overcurrent detection comparator when COMP = 0:

[0087]

[0088] The IPTAT in the formula comes from the over-temperature protection circuit in Section 4.6, and increases with increasing temperature. Therefore, the threshold voltage VCFTH when the CL signal flips will decrease with increasing temperature. The over-current detection circuit designed in this section is combined with the circuits in Sections 4.6 and 4.8, and can ultimately achieve the function that the threshold current IL of the chip over-current detection decreases with increasing temperature. One thing to note is that R3 in this module must match the two resistors in the over-temperature protection circuit to reduce the error caused by the change of R3 resistance value with process angle and temperature, and improve the robustness of the circuit.

[0089] The above description is only a further embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and concepts of the present invention within the scope disclosed by the present invention, which belong to the protection scope of the present invention.

Claims

1. H-bridge motor driver chip based on segmented current drive technology, characterized by: Including H-bridge output stage circuit: composed of four LDMOS, responsible for the high voltage and high current output of the power stage power supply; High-side drive circuit: converts the high-side tube logic control signal from the logic control part into a switch tube drive signal with a certain driving capability in the high-side tube power domain; Low-side drive circuit: converts the low-side tube logic control signal from the logic control part into a switch tube drive signal with a certain driving capability in the low-side tube power domain; Logic control: Generates logic control signals for controlling the four switch tubes of the H-bridge according to 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; Over-temperature protection module: generates over-temperature current limiting signal and over-temperature shutdown signal. The over-temperature shutdown signal has a hysteresis characteristic and generates a current with a positive temperature coefficient to reduce the over-current threshold of the over-current protection module at high temperature. Current sampling module: This module samples the output current of the H-bridge and generates a current that is equal to the output current I OUT Proportional sampling current I CF from CF Pin output to external resistor R CF superior; Overcurrent protection module: monitors the CF pin voltage. 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 the freewheeling state. The current limiting threshold will become smaller when the temperature rises. Current mirror bias circuit: mirrors the bias current input from the IB pin to each submodule as a bias; High-side floating ground generation circuit: Provides the high-side floating ground voltage V required by HS HGND =V S -3.3V, receiving the sink current from the high-side driver circuit and generating the Miller reference voltage V MILLER,REF .

2. The H-bridge motor driver chip based on segmented current driving technology according to claim 1, characterized in that: The current sampling module includes a SenseFET and a low-side switch tube with a size ratio of 1:K. Through a four-stage op amp negative feedback loop, the VOUT and VSENSE voltages are clamped to a virtual short to obtain the sampling current ISENSE, and ISENSE: IOUT = (W / L)SenseFET / (W / L)LS = 1:K; In the output part, the sampling current is mirrored to ICF by the current mirror formed by M20 and M21, and then output from the CF pin to the external resistor RCF after increasing the output resistance through a gain enhancement structure, generating a sampling voltage VCF proportional to the output current; The M21 current mirror is in the VHGND to VS voltage domain, so the sampling voltage VCF can be increased to exceed the VLDO voltage; The relationship between the sampling voltage VCF and the output current IOUT is as follows: The current sampling amplifier uses a two-stage cascode structure with PMOS as the input pair tube; A feedback loop is formed from the negative input terminal of the op amp to M24, M20, and M19.

3. The H-bridge motor driver chip based on segmented current driving technology according to claim 2, characterized in that: 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. An over-voltage threshold VCFTH is set for VCF to determine whether the output current IOUT is over-current.

4. The H-bridge motor driver chip based on segmented current driving technology according to claim 3 is characterized in that: The VCF sampling circuit samples the voltage VCF of the CF pin through a resistor network; The resistance value of the resistor network R0-R2 needs to be as large as possible to reduce the impact of the branch current on ICF; Ignoring the shunt of the resistor network, the sampled voltage VA at point A and the voltage VB at point B can be calculated by equations (4.22) and (4.23) respectively. The A or B node is connected to the negative input terminal of the comparator COMP1 through a two-way selector to achieve the hysteresis function; The output signal COMP of the comparator is used as the control signal of the two-way selector; When COMP = 0, point A is connected to the negative input of comparator COMP1, corresponding to the lower VCF threshold voltage V CFTH =V CFTH- ; When COMP = 1, point B is connected to the negative input of comparator COMP1, corresponding to a higher V CF Threshold voltage VCFTH = V CFTH+ ; The current limit threshold adjustment circuit converts the external bandgap reference voltage V BG After passing through a BUFFER with current output capability and resistor R3, it is connected to the positive input terminal of comparator COMP1. At the same time, the positive input terminal of COMP1 is also connected to the branch that generates IPTAT in the over-temperature protection circuit.

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