An over-temperature protection circuit and a motor drive circuit adaptable to ambient temperature difference

Abstract

The present invention discloses an over-temperature protection circuit and a motor drive circuit adaptable to ambient temperature difference, which includes a power-stage sensing MOS transistor M1, a current mirror circuit, a resistor R1, a current source Iptat, and a comparator CMP. The drain of the power-stage sensing MOS transistor M1 is connected to the input end of the current mirror circuit. The gate of the power-stage sensing MOS transistor M1 is connected to a zero-temperature-drift voltage V0. The output end of the current mirror circuit is connected to one end of the resistor R1, one end of the current source Iptat, and the non-inverting input end of the comparator CMP. The source of the power-stage sensing MOS transistor M1, the other end of the resistor R1, and the other end of the current source Iptat are grounded. The inverting input end of the comparator CMP is connected to a reference voltage Vref. The output end of the comparator CMP generates an over-temperature protection control signal OTP. The temperature difference threshold generated by the present invention can be automatically changed with the change of the ambient temperature.

Description

Technical Field

[0001] The present invention relates to a protection circuit and a motor drive circuit, in particular to an over-temperature protection circuit and a motor drive circuit that adapt to ambient temperature difference, and belongs to the technical field of semiconductor integrated circuits. Background Art

[0002] In a motor drive circuit, due to the large current flowing through the power stage, its temperature is often higher than the ambient temperature. By sensing the difference between the temperature of the power stage and the ambient temperature (the temperature of the control circuit), the power stage can be protected quickly. For different ambient temperatures, different difference thresholds should be set. For example, when the ambient temperature is low, even if the temperature of the power stage is much higher than the ambient temperature, the circuit will not have the risk of burning out. When the ambient temperature is high, if the temperature of the power stage is slightly higher than the ambient temperature, the chip may be burned out. At the same time, the device used to sense the temperature of the power stage should preferably fully reflect the temperature of the power stage. That is, two problems: 1. The temperature difference threshold should be related to the ambient temperature. When the ambient temperature is small, the temperature difference threshold is large, and vice versa. This threshold is preferably temperature-variable. 2. The device used to sense the temperature of the power stage should preferably be able to fully reflect the temperature condition of the power stage. The background art described above cannot achieve this.

[0003] Currently, the existing related technologies often sample the temperature of the power stage based on transistors, diodes or resistors, and cannot fully reflect the temperature information of the power stage because different devices have different temperature characteristics. At the same time, the existing related technologies either have only one temperature difference threshold or divide the temperature difference threshold according to the ambient temperature. Having only one temperature difference threshold is the least flexible. Although the method of dividing into grades is more flexible, in fact, for different temperatures in the same grade, different temperature difference thresholds should also be corresponding. In the method of dividing into grades, the differences between more subtle different temperatures are masked. At the same time, when switching between different grades, it may also cause circuit instability, resulting in problems such as false triggering of over-temperature protection. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an over-temperature protection circuit and a motor drive circuit that adapt to ambient temperature difference, and the temperature difference threshold can be automatically changed with the change of the ambient temperature.

[0005] To solve the above technical problem, the technical solution adopted by the present invention is:

[0006] An over-temperature protection circuit adaptable to ambient temperature difference includes a power-stage sensing MOS transistor M1, a current mirror circuit, a resistor R1, a current source Iptat, and a comparator CMP. The drain of the power-stage sensing MOS transistor M1 is connected to the input end of the current mirror circuit. The gate of the power-stage sensing MOS transistor M1 is connected to the zero-temperature-drift voltage V0. The output end of the current mirror circuit is connected to one end of the resistor R1, one end of the current source Iptat, and the non-inverting input end of the comparator CMP. The source of the power-stage sensing MOS transistor M1, the other end of the resistor R1, and the other end of the current source Iptat are grounded. The inverting input end of the comparator CMP is connected to the reference voltage V ref , and the output end of the comparator CMP generates an over-temperature protection control signal OTP.

[0007] Further, the current mirror circuit includes PMOS transistors M2, M3, M4, and M5. The sources of the PMOS transistor M4 and the PMOS transistor M5 are connected to the power supply VDD. The gate of the PMOS transistor M4 is connected to the drain of the PMOS transistor M4, the source of the PMOS transistor M2, and the gate of the PMOS transistor M5. The drain of the PMOS transistor M5 is connected to the source of the PMOS transistor M3. The gate of the PMOS transistor M2 is connected to the drain of the PMOS transistor M2 and the gate of the PMOS transistor M3 and serves as the input end of the current mirror circuit. The drain of the PMOS transistor M3 serves as the output end of the current mirror circuit.

[0008] Further, the ratio of the width-to-length ratio of the PMOS transistor M2 to the PMOS transistor M3 is 1:K, and the ratio of the width-to-length ratio of the PMOS transistor M4 to the PMOS transistor M5 is 1:K.

[0009] Further, the current source Iptat includes PMOS transistor PM1, PMOS transistor PM2, PMOS transistor PM3, PMOS transistor PM4, PMOS transistor PM5, PMOS transistor PM6, NMOS transistor NM1, NMOS transistor NM2, NMOS transistor NM3, bipolar transistor Q1, bipolar transistor Q2, and resistor R2. The sources of PMOS transistor PM1, PMOS transistor PM3, PMOS transistor PM5, and the drain of NMOS transistor NM1 are connected to the power supply VDD. The gate of PMOS transistor PM1 is connected to the gates of PMOS transistor PM3, PMOS transistor PM5, the drain of PMOS transistor PM1, and the source of PMOS transistor PM2. The gate of PMOS transistor PM2 is connected to the gates of PMOS transistor PM4, PMOS transistor PM6, the drain of PMOS transistor PM2, and the collector of bipolar transistor Q1. The drain of PMOS transistor PM3 is connected to the source of PMOS transistor PM4. The drain of PMOS transistor PM5 is connected to the source of PMOS transistor PM6. The drain of PMOS transistor PM4 is connected to the gate of NMOS transistor NM1 and the collector of bipolar transistor Q2. The drain of PMOS transistor PM6 is connected to the drains of NMOS transistor NM2, the gate of NMOS transistor NM2, and the gate of NMOS transistor NM3. The bases of bipolar transistor Q1 and bipolar transistor Q2 and the source of NMOS transistor NM1 are connected. The emitter of bipolar transistor Q1 is connected to one end of resistor R2. The other end of resistor R2, the emitter of bipolar transistor Q2, the source of NMOS transistor NM2, and the source of NMOS transistor NM3 are grounded. A current I is generated at the drain of NMOS transistor NM3 PTAT .

[0010] Further, the reference voltage V ref is a zero temperature coefficient voltage generated by bandgap, and resistor R1 is a zero temperature coefficient resistor.

[0011] A motor drive circuit includes a first over-temperature protection circuit, a second over-temperature protection circuit, a first half-bridge control circuit, a second half-bridge control circuit, transistor M11, transistor M21, transistor M12, and transistor M22. The first over-temperature protection circuit and the second over-temperature protection circuit adopt an over-temperature protection circuit with an adaptive ambient temperature difference. The output terminal of the first over-temperature protection circuit is connected to the OTP1 terminal of the first half-bridge control circuit, and the output terminal of the second over-temperature protection circuit is connected to the OTP2 terminal of the second half-bridge control circuit. The GH1 terminal of the first half-bridge control circuit is connected to the gate of transistor M11, the GL1 terminal of the first half-bridge control circuit is connected to the gate of transistor M12, the GH2 terminal of the second half-bridge control circuit is connected to the gate of transistor M21, and the GL2 terminal of the second half-bridge control circuit is connected to the gate of transistor M22. The source of transistor M11 and the drain of transistor M12 are connected to one end of the motor coil L2, and the source of transistor M21 and the drain of transistor M22 are connected to the other end of the motor coil L2.

[0012] Compared with the prior art, the present invention has the following advantages and effects:

[0013] 1. The present invention adopts a current that varies with the ambient temperature. This current that varies with the ambient temperature and the current that varies with the power stage temperature jointly generate a temperature difference threshold. The temperature difference threshold generated by this method can automatically change with the change of the ambient temperature.

[0014] 2. During the working process of the present invention, the circuit will not be switched, which is relatively stable. And there is a corresponding temperature difference threshold for each degree of ambient temperature. The temperature difference threshold is slow-changing and continuous, which can maximize the load-carrying capacity of the power stage.

[0015] 3. The present invention adopts a MOS transistor of the same type as the power stage MOS transistor and the same size as one of its fingers. Its temperature characteristics are exactly the same as those of the power stage. The present invention uses this sensing MOS transistor to generate a current, and the magnitude of this current can fully reflect the temperature change of the power stage. Description of the Drawings

[0016] Figure 1 It is a schematic diagram of an over-temperature protection circuit with an adaptive ambient temperature difference according to the present invention.

[0017] Figure 2 It is a circuit diagram of the current source Iptat according to the present invention.

[0018] Figure 3 It is a schematic diagram of the motor drive circuit according to the present invention. Detailed Embodiments

[0019] To elaborate in detail on the technical solutions adopted by the present invention to achieve the intended technical purposes, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only partial embodiments of the present invention, rather than all embodiments. Moreover, without creative efforts, the technical means or technical features in the embodiments of the present invention can be replaced. The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0020] As Figure 1 shown, an over-temperature protection circuit with self-adaptive ambient temperature difference of the present invention includes a power-stage sensing MOS transistor M1, a current mirror circuit, a resistor R1, a current source Iptat, and a comparator CMP. The drain of the power-stage sensing MOS transistor M1 is connected to the input end of the current mirror circuit. The gate of the power-stage sensing MOS transistor M1 is connected to the zero-temperature-drift voltage V0. The output end of the current mirror circuit is connected to one end of the resistor R1, one end of the current source Iptat, and the positive-phase input end of the comparator CMP. The source of the power-stage sensing MOS transistor M1, the other end of the resistor R1, and the other end of the current source Iptat are grounded. The reverse input end of the comparator CMP is connected to the reference voltage V ref , and the output end of the comparator CMP generates an over-temperature protection control signal OTP.

[0021] The current mirror circuit includes PMOS transistors M2, M3, M4, and M5. The sources of the PMOS transistor M4 and the PMOS transistor M5 are connected to the power supply VDD. The gate of the PMOS transistor M4 is connected to the drain of the PMOS transistor M4, the source of the PMOS transistor M2, and the gate of the PMOS transistor M5. The drain of the PMOS transistor M5 is connected to the source of the PMOS transistor M3. The gate of the PMOS transistor M2 is connected to the drain of the PMOS transistor M2 and the gate of the PMOS transistor M3 and serves as the input end of the current mirror circuit. The drain of the PMOS transistor M3 serves as the output end of the current mirror circuit.

[0022] The ratio of the width-to-length ratio of the PMOS transistor M2 to the PMOS transistor M3 is 1:K, and the ratio of the width-to-length ratio of the PMOS transistor M4 to the PMOS transistor M5 is 1:K.

[0023] As Figure 2As shown, the current source Iptat includes PMOS transistors PM1, PMOS transistor PM2, PMOS transistor PM3, PMOS transistor PM4, PMOS transistor PM5, PMOS transistor PM6, NMOS transistors NM1, NMOS transistor NM2, NMOS transistor NM3, bipolar transistors Q1, bipolar transistor Q2 and resistor R2. The sources of PMOS transistor PM1, PMOS transistor PM3, PMOS transistor PM5 and the drain of NMOS transistor NM1 are connected to the power supply VDD. The gate of PMOS transistor PM1 is connected to the gates of PMOS transistor PM3, PMOS transistor PM5, the drain of PMOS transistor PM1 and the source of PMOS transistor PM2. The gate of PMOS transistor PM2 is connected to the gates of PMOS transistor PM4, PMOS transistor PM6, the drain of PMOS transistor PM2 and the collector of bipolar transistor Q1. The drain of PMOS transistor PM3 is connected to the source of PMOS transistor PM4. The drain of PMOS transistor PM5 is connected to the source of PMOS transistor PM6. The drain of PMOS transistor PM4 is connected to the gate of NMOS transistor NM1 and the collector of bipolar transistor Q2. The drain of PMOS transistor PM6 is connected to the drain of NMOS transistor NM2, the gate of NMOS transistor NM2 and the gate of NMOS transistor NM3. The base of bipolar transistor Q1 is connected to the base of bipolar transistor Q2 and the source of NMOS transistor NM1. The emitter of bipolar transistor Q1 is connected to one end of resistor R2. The other end of resistor R2, the emitter of bipolar transistor Q2, the source of NMOS transistor NM2 and the source of NMOS transistor NM3 are grounded, and the drain of NMOS transistor NM3 generates current I PTAT .

[0024] PMOS transistors PM1, PMOS transistor PM2, PMOS transistor PM3, PMOS transistor PM4, PMOS transistor PM5, PMOS transistor PM6 form a 1:1:1 PMOS current mirror, and NMOS transistors NM2 and NM3 form a 1:K1 NMOS current mirror.

[0025] The current source Iptat mainly generates a current I0 with a positive temperature coefficient using the voltage difference between the base-emitter voltages VBE of the two bipolar transistors Q1 and Q2. The current I0 generates a current I2 through the PMOS current mirror, and the current I2 generates a current I through the NMOS current mirror PTAT . The current I0 and the current I PTAT are expressed as follows:

[0026]

[0027]

[0028] Among them, VBE1 is the base-emitter voltage of transistor Q1, VBE2 is the base-emitter voltage of transistor Q2, the structural ratio of transistor Q1 to transistor Q2 is 8, V T is the thermal voltage of the transistor, R2 is the resistance value of resistor R2, k is the Boltzmann constant, T is the temperature, q is the electron charge, and K1 is the proportionality coefficient of the NMOS current mirror.

[0029] The current source Iptat is set in the control module and is at a certain distance from the power transistor. This circuit can sample the temperature of the control module in real time, that is, the ambient temperature. When the ambient temperature changes, the generated current I PTAT will change accordingly. The current synthesized by this current and the current sampled by the power stage will also change, and the temperature difference threshold voltage will change. In this way, the temperature difference will change according to the change of the ambient temperature.

[0030] The reference voltage V ref is the zero temperature coefficient voltage generated by the bandgap, and the resistor R1 is a zero temperature coefficient resistor.

[0031] The working principle of an over-temperature protection circuit with adaptive ambient temperature difference of the present invention is as follows:

[0032] The power stage sensing MOS transistor M1, as a device for sensing the temperature of the power stage, has a gate voltage of zero temperature drift voltage V0, which remains unchanged at different temperatures. The reference voltage Vref is the zero temperature coefficient voltage generated by the bandgap, and the resistor R1 is a resistor with a very small temperature coefficient. Ignoring its temperature coefficient, the resistor R1 is considered a zero temperature coefficient resistor.

[0033] Then the current I1 generated by the power stage sensing MOS transistor M1 can be expressed as:

[0034] ; (1)

[0035] Among them, is the average mobility of electrons in the channel, is the gate oxide capacitance of the gear area, is the aspect ratio of the transistor channel width to length, is the threshold voltage of the power stage sensing MOS transistor M1.

[0036] The threshold voltage of the power stage sensing MOS transistor M1 has the following relationship with the temperature T:

[0037] ; (2)

[0038] ; (3)

[0039] Among them, is the energy bandgap width, is the electronic charge, is the Fermi potential related to the doping concentration of the substrate, is the substrate bias coefficient,

[0040] Therefore, the threshold voltage of the power-stage sensing MOS transistor M1 decreases as the temperature T increases and is an inverse proportional function. The threshold voltage The slope of the decrease with respect to the temperature T is typically between -0.5 mV / °C and -4 mV / °C.

[0041] From formulas (1), (2), and (3), we can obtain:

[0042] ; (4)

[0043] where m is a coefficient related to V0 - Formula (4) gives the relationship between the current I1 and the temperature T, indicating that the current I1 is a current with a positive temperature coefficient.

[0044] gives the expression of the sensing voltage V sense :

[0045] ; (5)

[0046] where K is the proportionality factor of the current mirror circuit, and R is the resistance value of the resistor R1. I PTAT is a current with a positive temperature coefficient generated by the current source Iptat. For the convenience of derivation, the current I PTAT is approximately expressed as:

[0047] ; (6)

[0048] where m1 is a positive number representing the relationship between the current I PTAT and the temperature T.

[0049] Let the sensing voltage V sense be differentiated with respect to the temperature T:

[0050] ; (7)

[0051] By controlling the proportionality factor K of the current mirror circuit, the expression in formula (7) is made positive. Then it can be ensured that if the temperature T1 of the power transistor M1 is equal to the ambient temperature T2, the sensing voltage V sense will increase as T1 and T2 increase. And when the sensing voltage V sense exceeds V ref , the OTP will be triggered.

[0052] This means that for the implementation of the functions described above: when the ambient temperature is relatively low, a relatively large temperature difference between the power stage temperature and the ambient temperature is allowed; when the ambient temperature is relatively high, the temperature difference threshold between the power stage temperature and the ambient temperature is appropriately reduced.

[0053] For example, when the temperature T1 of the power transistor M1 and the ambient temperature T2 are both 30 °C, V ref - V sense is Va.

[0054] When the temperature T1 of the power transistor M1 and the ambient temperature T2 are both 80 °C, V ref - V sense is Vb. Since the sensed voltage V sense has a positive temperature coefficient, so Vb < Va, that is, the higher the ambient temperature, the smaller the temperature protection threshold. It also realizes that the higher the ambient temperature T2, the easier it is for the temperature rise of the power transistor temperature T1 to trigger the OTP function. It can effectively protect the chip in a high-temperature environment and at the same time maximize the load-carrying capacity of the power transistor in a low-temperature environment.

[0055] As Figure 3 shown, a motor drive circuit includes a first over-temperature protection circuit, a second over-temperature protection circuit, a first half-bridge control circuit, a second half-bridge control circuit, transistors M11, M21, M12, and M22. The first over-temperature protection circuit and the second over-temperature protection circuit adopt an over-temperature protection circuit with an adaptive ambient temperature difference. The output terminal of the first over-temperature protection circuit is connected to the OTP1 terminal of the first half-bridge control circuit, and the output terminal of the second over-temperature protection circuit is connected to the OTP2 terminal of the second half-bridge control circuit. The GH1 terminal of the first half-bridge control circuit is connected to the gate of the transistor M11, the GL1 terminal of the first half-bridge control circuit is connected to the gate of the transistor M12, the GH2 terminal of the second half-bridge control circuit is connected to the gate of the transistor M21, and the GL2 terminal of the second half-bridge control circuit is connected to the gate of the transistor M22. The source of the transistor M11 and the drain of the transistor M12 are connected to one end of the motor coil L2, and the source of the transistor M21 and the drain of the transistor M22 are connected to the other end of the motor coil L2.

[0056] The motor drive circuit consists of two half - bridges to form a full - bridge, and each half - bridge is provided with a relative temperature protection. When the power stage of the first over - temperature protection circuit senses that the temperature of MOS transistor M1 rises, the induced current increases and the induced voltage also rises. When the induced voltage is greater than the reference voltage, the over - temperature protection control signal OTP of the first over - temperature protection circuit becomes high level, closing the GH1 and GL1 ports of the first half - bridge control circuit. Similarly, when the power stage of the second over - temperature protection circuit senses that the temperature of MOS transistor M1 rises to the threshold, the GH2 and GL2 ports of the second half - bridge control circuit are closed. When the ambient temperature is high, because the sensed voltage has a positive temperature coefficient, the starting point of all sensed voltages is high, and OTP will occur with a slight increase in the temperature of the power stage. Conversely, when the temperature is low, the power stage needs to increase more temperature than the control stage to trigger OTP. In this way, the chip can be effectively protected in a high - temperature environment, and at the same time, the load - carrying capacity of the power transistor can be maximally developed in a low - temperature environment.

[0057] The present invention uses a current that varies with the ambient temperature. This current that varies with the ambient temperature and the current that varies with the power - stage temperature jointly generate a temperature - difference threshold. The temperature - difference threshold generated by this method can automatically change with the change of the ambient temperature; during the working process of the present invention, the circuit will not be switched, which is relatively stable, and there is a corresponding temperature - difference threshold for each degree of ambient temperature. The temperature - difference threshold is slow - changing and continuous, and the load - carrying capacity of the power stage can be maximally developed; the present invention uses a MOS transistor of the same type as the power - stage MOS transistor and the same size as one of the fingers, and its temperature characteristics are exactly the same as those of the power stage. The present invention uses this sensing MOS transistor to generate a current, and the magnitude of this current can fully reflect the temperature change of the power stage.

[0058] The above - mentioned are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art, within the scope of the technical solution of the present invention, can make some changes or modifications to the above - disclosed technical content to form equivalent embodiments of equivalent changes. However, as long as it does not depart from the content of the technical solution of the present invention, according to the technical essence of the present invention, any simple modification, equivalent replacement, and improvement made to the above embodiments within the spirit and principle of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. An over-temperature protection circuit adaptable to ambient temperature difference, characterized in that: It includes a power-stage sensing MOS transistor M1, a current mirror circuit, a resistor R1, a current source Iptat, and a comparator CMP. The drain of the power-stage sensing MOS transistor M1 is connected to the input end of the current mirror circuit. The gate of the power-stage sensing MOS transistor M1 is connected to the zero-temperature-drift voltage V0. The output end of the current mirror circuit is connected to one end of the resistor R1, one end of the current source Iptat, and the non-inverting input end of the comparator CMP. The source of the power-stage sensing MOS transistor M1, the other end of the resistor R1, and the other end of the current source Iptat are grounded. The inverting input end of the comparator CMP is connected to the reference voltage V ref , and the output end of the comparator CMP generates an over-temperature protection control signal OTP; The current source Iptat includes PMOS transistor PM1, PMOS transistor PM2, PMOS transistor PM3, PMOS transistor PM4, PMOS transistor PM5, PMOS transistor PM6, NMOS transistor NM1, NMOS transistor NM2, NMOS transistor NM3, bipolar transistor Q1, bipolar transistor Q2, and resistor R2. The sources of PMOS transistor PM1, PMOS transistor PM3, PMOS transistor PM5, and the drain of NMOS transistor NM1 are connected to the power supply VDD. The gate of PMOS transistor PM1 is connected to the gates of PMOS transistor PM3, PMOS transistor PM5, the drain of PMOS transistor PM1, and the source of PMOS transistor PM2. The gate of PMOS transistor PM2 is connected to the gates of PMOS transistor PM4, PMOS transistor PM6, the drain of PMOS transistor PM2, and the collector of bipolar transistor Q1. The drain of PMOS transistor PM3 is connected to the source of PMOS transistor PM4. The drain of PMOS transistor PM5 is connected to the source of PMOS transistor PM6. The drain of PMOS transistor PM4 is connected to the gate of NMOS transistor NM1 and the collector of bipolar transistor Q2. The drain of PMOS transistor PM6 is connected to the drains of NMOS transistor NM2, the gate of NMOS transistor NM2, and the gate of NMOS transistor NM3. The base of bipolar transistor Q1 is connected to the base of bipolar transistor Q2 and the source of NMOS transistor NM1. The emitter of bipolar transistor Q1 is connected to one end of resistor R2. The other end of resistor R2, the emitter of bipolar transistor Q2, the source of NMOS transistor NM2, and the source of NMOS transistor NM3 are grounded, and the drain of NMOS transistor NM3 generates current I PTAT .

2. The over-temperature protection circuit adaptable to ambient temperature difference according to claim 1, wherein: The current mirror circuit includes PMOS transistors M2, M3, M4, and M5. The sources of PMOS transistor M4 and PMOS transistor M5 are connected to the power supply VDD. The gate of PMOS transistor M4 is connected to the drain of PMOS transistor M4, the source of PMOS transistor M2, and the gate of PMOS transistor M5. The drain of PMOS transistor M5 is connected to the source of PMOS transistor M3. The gate of PMOS transistor M2 is connected to the drain of PMOS transistor M2 and the gate of PMOS transistor M3 and serves as the input terminal of the current mirror circuit. The drain of PMOS transistor M3 serves as the output terminal of the current mirror circuit.

3. An over-temperature protection circuit adaptable to environmental temperature difference according to claim 2, characterized in that: The ratio of the width-to-length ratio of PMOS transistor M2 to PMOS transistor M3 is 1:K, and the ratio of the width-to-length ratio of PMOS transistor M4 to PMOS transistor M5 is 1:K.

4. An over-temperature protection circuit for adapting to environmental temperature differences according to claim 1, characterized in that: The reference voltage V ref is the zero temperature coefficient voltage generated by the bandgap, and the resistor R1 is a zero temperature coefficient resistor.

5. A motor drive circuit, characterized in that: It includes a first over-temperature protection circuit, a second over-temperature protection circuit, a first half-bridge control circuit, a second half-bridge control circuit, transistors M11, M21, M12, and M22. The first over-temperature protection circuit and the second over-temperature protection circuit adopt the over-temperature protection circuit with adaptive ambient temperature difference described in any one of claims 1-4. The output terminal of the first over-temperature protection circuit is connected to the OTP1 terminal of the first half-bridge control circuit. The output terminal of the second over-temperature protection circuit is connected to the OTP2 terminal of the second half-bridge control circuit. The GH1 terminal of the first half-bridge control circuit is connected to the gate of transistor M11. The GL1 terminal of the first half-bridge control circuit is connected to the gate of transistor M12. The GH2 terminal of the second half-bridge control circuit is connected to the gate of transistor M21. The GL2 terminal of the second half-bridge control circuit is connected to the gate of transistor M22. The source of transistor M11 and the drain of transistor M12 are connected to one end of the motor coil L2. The source of transistor M21 and the drain of transistor M22 are connected to the other end of the motor coil L2.

Images