Patent Description:
The automobile industry is witnessing a development tendency that electric vehicles are replacing fossil fuel vehicles. In a high-voltage loop of the electric vehicle, a relay is typically used as a switch for on/off switching. Switching on/off of the relay is controlled by a microcontroller of a battery management system. However, the inventors have found that there is at least the following problem in some cases: potential unexpected reset of the microcontroller during driving, causing great safety hazards to the vehicle.

<CIT> discloses a control apparatus. The control apparatus includes a microcontroller, an auxiliary circuit, a delay module and a logical circuit; the microcontroller is connected to a first input end of the logical circuit via the auxiliary circuit and connected to a second input end of the logical circuit via the delay module, and an output end of the logical circuit is connected to a device to be controlled; if the microcontroller is reset in a process of outputting the closing control signal, a delay disabling signal becomes invalid, the delay module is enabled to output the closing control signal within a preset delay time, wherein the delay time is greater than or equal to a reset time.

One or more embodiments are used as examples for description by using figures in corresponding accompanying drawings. These example descriptions impose no limitation on the embodiments. Elements with a same reference sign in the accompanying drawings represent similar elements. Unless otherwise stated, the figures in the accompanying drawings impose no limitation on a scale.

To describe the technical solutions in the embodiments of this application or in the prior art more clearly, the following briefly describes the accompanying drawings required for describing the embodiments or the prior art. Apparently, the accompanying drawings in the following description show merely some of the embodiments of this application, and a person of ordinary skill in the art may still derive other drawings from these accompanying drawings without creative efforts.

To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following describes the embodiments of this application in detail with reference to the accompanying drawings. However, a person of ordinary skill in the art can understand that many technical details are put forward in the embodiments of this application to make a reader better understand this application. However, even without the technical details and various changes and modifications on a basis of the following embodiments, the technical solution claimed in this application can be implemented.

In the descriptions of this application, it should be noted that, unless otherwise stated, "plurality" means two or more; and the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right", "inside", "outside", and the like are merely intended to facilitate the descriptions of this application and simplify the descriptions other than indicate or imply that the apparatuses or components must have specific orientations, or be constructed and operated for a specific orientation, and therefore shall not be construed as a limitation to this application. In addition, the terms "first", "second", and "third" are merely intended for a purpose of description, and shall not be understood as an indication or implication of relative importance. "Vertical" means being within an allowable range of an error other than being strictly vertical. "Parallel" means being within an allowable range of an error other than being strictly parallel.

The orientations used in the following descriptions are all directions shown in the figure, and are not intended to limit the specific structure in the application. In the descriptions of this application, it should be further noted that unless otherwise specified and defined explicitly, the terms "installment", "link", and "connection" should be understood in their general senses. For example, the terms may be a fixed connection, a detachable connection, or an integrated connection, or may be a direct connection, or an indirect connection through an intermediate medium. A person of ordinary skills in the art can understand specific meanings of these terms in this application based on specific situations.

As shown in <FIG>, a drive circuit includes a low-side driver module <NUM> and a delay module <NUM>. The delay module <NUM> is configured to output a delay signal of preset duration to the low-side driver module <NUM> in a case that a control module <NUM> is being reset. The low-side driver module <NUM> is configured to: according to the delay signal of preset duration, maintain a first state within the preset duration, the first state being the same as a second state, where the second state is a working state of the low-side driver module <NUM> before the control module <NUM> is reset, and the second state includes being on or off.

In this example, the control module <NUM> cannot output a control signal during the reset. When the control module <NUM> is being reset, the delay module <NUM> outputs a delay signal of a level the same as that for a drive signal output by the control module <NUM> before the reset, so that in a case that the control module <NUM> is being reset, the low-side driver module <NUM> can maintain a state before the reset, to avoid a safety problem caused by an abrupt state change of the low-side driver module <NUM> when the control module <NUM> is being reset. When the control module <NUM> is being reset, a delay function of the entire circuit is implemented through a separate delay module <NUM>, thereby simplifying drive logic of the control module <NUM> and a circuit design. This application relates to a drive circuit. This application is approximately the same as the above example, with a main difference as follows: An example in which the drive circuit is configured to drive a load is used to describe a connection manner of the drive circuit and the load, and a function of the drive circuit. Specifically, as shown in <FIG>, the drive circuit is configured to drive a load <NUM>, the load <NUM> is grounded through a low-side driver module <NUM>. The delay module <NUM> is configured to: output a delay signal of preset duration to the low-side driver module <NUM> in a case that a control module <NUM> is being reset. The preset duration is set based on reset duration of the control module <NUM>. For example, the preset duration is greater than maximum reset duration of the control module <NUM>. For example, if the reset duration of the control module <NUM> ranges approximately from <NUM> second to <NUM> seconds, the preset duration is greater than <NUM> seconds. The low-side driver module <NUM> is configured to: according to the delay signal of preset duration, maintain a first state within the preset duration, where the first state is the same as a second state. The second state is a working state of the low-side driver module <NUM> before the control module <NUM> is reset, and the second state includes being on or off. When the control module <NUM> is working properly, the low-side driver module <NUM> is configured to perform switching-on or switching-off based on the drive signal from the control module <NUM>. In this application, when the control module <NUM> is being reset, the delay module <NUM> outputs a delay signal of a level the same as that of a drive signal output by the control module <NUM> before the reset, so that in a case that the control module <NUM> is being reset, the low-side driver module <NUM> can maintain a state before the reset, to avoid a safety problem caused by an abrupt state change of the low-side driver module <NUM> when the control module <NUM> is being reset. The control module <NUM> can output the drive signal to control the low-side driver module <NUM> to switch on or off. When the control module <NUM> is being reset, a delay function of the entire circuit is implemented through a separate delay module <NUM>, thereby simplifying drive logic of the control module <NUM> and a circuit design.

In an embodiment, a first terminal of the load <NUM> is connected to a drive power supply V1, and a second terminal of the load <NUM> is grounded through the low-side driver module <NUM>.

It should be noted that a person skilled in the art can understand that the drive power supply is configured to supply power to the load <NUM>. A type of the drive power supply is determined based on an application scenario. For example, when this application is applied to an electric vehicle, the drive power source is usually a vehicle lead-acid battery, and the ground is a vehicle low-voltage ground. The type of the drive power supply is not limited in this application.

It should be noted that a person skilled in the art can understand that the load <NUM> in this application may be a device such as a relay or a contactor, or may be another device such as a pump (PUMP) or a valve. Details are not listed herein.

An example in which the load <NUM> is the relay and the control module <NUM> is a microcontroller in a battery management system of a vehicle is used below to describe the drive circuit mentioned in this application. In the prior, in a high-voltage loop of the electric vehicle, a relay is usually used as a switch for connection or disconnection. Switching on and off of the relay are usually controlled by the microcontroller of the battery management system. However, the microcontroller may be reset during driving, and the reset duration is relatively short. When the microcontroller is being reset, no drive signal can be output. In this case, the relay abruptly switches off and the vehicle abruptly stops, causing a great safety hazard. In addition, disconnecting the relay with the load has great impact on service life of the relay. In this application, a delay module <NUM> is added between the low-side driver module <NUM> and the microcontroller. When the relay is on, if the microcontroller is being reset, the delay signal output by the delay module <NUM> to the low-side driver module <NUM> can keep the relay in an on state, so that the relay is not accidentally switched off. Likewise, in a case that the relay is in an off state, if the microcontroller is being reset, the delay signal output by the delay module <NUM> to the low-side driver module <NUM> can keep the relay in an off state, so that the relay is not accidentally switched on.

It should be noted that a person skilled in the art can understand that in this application, the vehicle field is used as an example to describe the drive circuit. In practical applications, the drive circuit may also be applied to another field. The application field of the drive circuit is not limited in this application.

In an embodiment, the delay module <NUM> includes a delay unit and a first pull-up unit; a first controlled terminal of the delay unit is connected to both the first pull-up unit and a first output terminal of the control module <NUM>, a second controlled terminal of the delay unit is connected to a second output terminal of the control module <NUM>, and an output terminal of the delay unit is connected to a control terminal of the low-side driver module <NUM>. The first pull-up unit pulls up an input signal of the first controlled terminal of the delay unit to a high level signal. The delay unit is configured to: when an electrical signal of a first level is detected at the first controlled terminal and an edge signal is detected at the second controlled terminal, output a delay signal of a second level to a low-side driver module <NUM>, to control the low-side driver module <NUM> to switch on; when an electrical signal of a first level is detected at the first controlled terminal and no edge signal is detected at the second controlled terminal, output a delay signal of a fourth level to a low-side driver module <NUM>, to control the low-side driver module <NUM> to switch off; and when an electrical signal of a third level is detected at the first controlled terminal, output a delay signal of a fourth level to a low-side driver module <NUM>, to control the low-side driver module <NUM> to switch off. The fourth level is a reverse level of the second level, the third level is a reverse level of the first level, and the low-side driver module <NUM> maintains an on state when receiving an electrical signal of the second level and switched off when receiving an electrical signal of the fourth level.

It should be noted that the edge signal may be a rising edge signal or a falling edge signal. A person skilled in the art can determine a circuit form of the delay unit based on working logic of the delay unit.

In an embodiment, in a case that the edge signal is a rising edge signal, the delay module <NUM> further includes a second pull-up unit, and the second pull-up unit is connected to the second controlled terminal of the delay unit.

In an embodiment, the first level and the second level are co-directional levels, the third level and the fourth level are co-directional levels, and the first level and the third level are reverse levels. It is assumed that the first level and the second level are high levels, the third level and the fourth level are low levels, a high-level delay signal output by the delay unit when a high-level electrical signal is detected at the first controlled terminal and an edge signal is detected at the second controlled terminal is a pulse signal, that is, a high-level pulse signal. Specifically, input and output level states that can be implemented by the delay unit are shown in Table <NUM>.

It should be noted that a person skilled in the art can understand that in practical applications, a delay time (namely, the preset duration) of the delay unit can be set based on a reset time of the control module <NUM>, so that the preset duration is greater than reset duration of the control module <NUM>. A resistance value, a capacitance value, and the like of a corresponding circuit device are selected based on the delay time of the delay unit. A specific circuit form of the delay unit is not limited in this application.

In an embodiment, either of the first pull-up unit and the second pull-up unit includes a pull-up resistor, a first terminal of the pull-up resistor is connected to a signal terminal of a pull-up power supply, and a second terminal of the pull-up resistor serves as an output terminal of the pull-up unit.

It should be noted that a person skilled in the art can understand that in practical applications, the first pull-up unit and the second pull-up unit may also use another circuit structure. The embodiment is only used as an example for illustration, and imposes no limitation on specific circuits of the first pull-up unit and the second pull-up unit.

It should be noted that a person skilled in the art can understand that in practical applications, a structure of the first pull-up unit may be the same as or different from a structure of the second pull-up unit. The embodiment is illustrated using an example that they are the same, but imposes no limitation on a circuit structure in actual use.

It should be noted that a person skilled in the art can understand that the signal terminal of the pull-up power supply may be an output terminal of the pull-up power supply, and a voltage output by the pull-up power supply may be the same as a high-level voltage of a signal output by the control module <NUM>. A voltage value of the pull-up power supply is not limited in this application.

The following uses an example in which the edge signal is the falling edge with reference to different forms of drive circuits and protective circuits to illustrate a working principle of the drive circuit.

In a first example, a delay unit includes a delay component. A first input terminal of the delay component is the first controlled terminal of the delay unit, a second input terminal of the delay component serves as the second controlled terminal of the delay unit, and an output terminal of the delay component serves as the output terminal of the delay unit. The delay component is configured to generate a delay signal of a corresponding level based on an electrical signal received by the first input terminal of the delay component and the electrical signal received by the second input terminal of the delay component, to control the low-side driver module <NUM> to switch on or off. For a level relationship between the electrical signal received by the first input terminal of the delay component, the electrical signal received by the second input terminal of the delay component, and the output delay signal, refer to descriptions in Table <NUM>.

In the first example, the low-side driver module <NUM> includes a low-side driver unit. The output terminal of the delay unit is connected to a control terminal of the low-side driver unit. In this example, a drive signal includes a drive signal of a second level and a drive signal of a fourth level; and the control module <NUM> may be configured to: after detecting a switch-on signal, output the drive signal of the second level to the low-side driver module <NUM>, to control the low-side driver module <NUM> to switch on; and output a control signal of the first level or the third level to the first controlled terminal of the delay module <NUM>, and output a control signal of a fifth level or a first pulse width modulation (Pulse Width Modulation, PWM) control signal to the second controlled terminal of the delay module <NUM>, to control the delay module <NUM> to output the electrical signal of the second level or the electrical signal of the fourth level. Because the control module <NUM> outputs the drive signal of the second level to the low-side driver module <NUM>, the low-side driver module <NUM> is in an on state regardless of whether the delay module <NUM> outputs the electrical signal of the second level or the electrical signal of the fourth level. When the control module <NUM> is being reset, the first controlled terminal of the delay unit is pulled up to the first level, and the second controlled terminal of the delay unit can detect the edge signal, to output a delay signal of the second level to the low-side driver module <NUM>, so that the low-side driver module <NUM> maintains an on state. After detecting a switch-off signal, the control module <NUM> outputs the drive signal of the fourth level to the low-side driver module <NUM>, and outputs the control signal of the third level to the first controlled terminal of the delay module <NUM> and the second controlled terminal of the delay module <NUM>. Because the control module <NUM> outputs the drive signal of the fourth level to the low-side driver module <NUM> and the delay module <NUM> outputs the delay signal of the fourth level to the low-side driver module <NUM>, the low-side driver module <NUM> is off. When the control module <NUM> is being reset, the first controlled terminal of the delay unit is pulled up to the first level, and the second controlled terminal of the delay unit cannot detect a specific edge signal, and therefore, the delay module <NUM> outputs the delay signal of the fourth level to the low-side driver module <NUM>, so that the low-side driver module <NUM> maintains an off state. A period of the first pulse width modulation PWM control signal is less than the preset duration; and when the edge signal is a rising edge signal, the fifth level is a low level, or when the edge signal is a falling edge signal, the fifth level is a high level.

The following uses an example to describe detection of a switch-on signal and a switch-off signal.

In some embodiments, the switch-on signal is a high-level signal, and the switch-off signal is a low-level signal. In order that a staff member controls the load <NUM>, a control loop may be disposed. The control loop includes a control power supply, a switch (such as a single-pole switch, a push-button switch, or the like), and a resistor that are connected in series in sequence. A current in the resistor is detected through a voltage detection circuit, and a detection result is output to the control module <NUM>. When the switch in the control loop is switched on, the voltage detection circuit detects a voltage value, and then a high-level signal is output to the control module <NUM>. The control module <NUM> receives the high-level signal, that is, detects a high-level signal, and then controls the load <NUM> to switch on according to the foregoing logic. When the switch in the control loop is switched off, the voltage detection circuit detects no voltage value, and then a low-level signal is output to the control module <NUM>. The control module <NUM> receives a low-level signal, that is, detects the low-level signal, and then controls the load <NUM> to switch off according to the foregoing logic.

It should be noted that a person skilled in the art can understand that in practical applications, the switch-on signal may alternatively be a switch-on command input by a staff member, and the switch-off signal may alternatively be an input switch-off command. For example, the control module <NUM> is connected to an input device, and the control module <NUM> detects a command input by the staff member through the input device. After detecting the switch-on command, the control module <NUM> controls the load <NUM> to switch on based on the foregoing logic. After detecting the switch-off command, the control module <NUM> controls the load <NUM> to switch off based on the foregoing logic. Manners of generating the switch-on signal and the switch-off signal are not limited in this application.

In some embodiments, the first level and the second level are co-directional levels, and the third level and the fourth level are co-directional levels.

In some embodiments, after detecting the switch-on signal, the control module <NUM> outputs the first level to the first controlled terminal of the delay module <NUM>, to ensure that when the control module <NUM> is being reset and the edge signal is detected at the second controlled terminal, the delay module <NUM> outputs a delay signal of the second level, so that a low-side driver module maintains an on state.

It is assumed that the load <NUM> is a relay and the low-side driver unit is a type-N transistor, the edge signal is the falling edge signal, the first level and the second level are high levels, and the third level and the fourth level are low levels. <FIG> is a schematic circuit diagram of the drive circuit. V1 represents the drive power supply, J1 represents the relay, M1 represents the low-side driver unit, Y1 represents the delay component, R represents the first input terminal of the delay component, B represents the second input terminal of the delay component, Q represents the output terminal of the delay component, V2 represents a first signal terminal of the pull-up power supply, and RT represents a first pull-up resistor. A level of the control signal (referred to as a control signal <NUM>) output by the control module <NUM> to the first controlled terminal of the delay unit may be set based on a working principle of the delay unit, and the control signal (referred to as a control signal <NUM>) output by the control module <NUM> to the second controlled terminal of the delay unit may be a constant-level signal (including a low-level signal and a high-level signal) or a pulse width modulation signal.

When the control signal <NUM> is the constant-level signal, the working principle of the drive circuit is as follows: When receiving a relay switch-on signal, the control module <NUM> outputs a high-level drive signal to the control terminal of the low-side driver unit, outputs a high-level control signal <NUM> to the port B of the delay component, and outputs a high-level control signal <NUM> to the port R of the delay component. In this case, a state of the port Q is a low level, and the low-side driver unit is switched on. When the control module <NUM> is being reset, output of the control module <NUM> is in a high-impedance state, the port B of the delay component changes from a high level to a low level, and a falling edge occurs. In addition, because there is the first pull-up unit, the port R remains at a high level, a high-level pulse is output at the port Q, the low-side driver unit maintains an on state, and the relay maintains the original on state. When receiving a relay switch-off signal, the control module <NUM> outputs a low-level drive signal to the control terminal of the low-side driver unit, outputs a low-level control signal <NUM> to the port B of the delay component, and outputs a low-level control signal <NUM> to the port R of the delay component (a low-level control signal <NUM> may alternatively be first output, and then a low-level drive signal is output to the control terminal of the low-side driver unit). In this case, a state of the port Q is a low level, and the low-side driver unit is switched off. When the relay is off and the control module <NUM> is being reset, the output of the control module <NUM> is in a high-impedance state, and the port B of the delay component is still at a low level (no falling edge). Because there is the first pull-up unit, input of the port R changes from the low level to the high level, output of the port Q is still at the low level, the state of the low-side driver unit does not change, and the relay is not accidentally switched on.

It should be noted that a person skilled in the art can understand that, if an interval between the control signal <NUM> and the drive signal is very short and less than action time of the relay, an output sequence of the control signal <NUM> and the drive signal may not be limited. If the interval between the control signal <NUM> and the drive signal is very long and greater than the action time of the relay, in this application, the low-level control signal <NUM> and control signal <NUM> are output firstly, and then the low-level drive signal is output.

It is worth mentioning that, the low-level control signal <NUM> is output before the low-level drive signal is output, thereby preventing the relay from being switched on and then being switched off caused by resetting of the microcontroller when the low-level control signal <NUM> is not sent after the low-level drive signal has been sent.

When the control signal <NUM> is the PWM signal, the working principle of the drive circuit is as follows: When receiving a relay switch-on signal, the control module <NUM> outputs a high-level drive signal to the control terminal of the low-side driver unit, outputs a high-level control signal <NUM> to the port R of the delay component, and outputs a PWM control signal <NUM> to the port B of the delay component, so that the low-side driver unit is switched on. Whenever a falling edge occurs in the control signal <NUM>, a high-level pulse is output at the port Q, which may be repeatedly triggered. When the delay time of the delay unit is greater than a PWM period, a high level is continuously output at the port Q. When the control module <NUM> is being reset, a high level is output at the port Q of the delay module <NUM>. It is assumed that a period of the control signal <NUM> is t, set delay time is T1, and T1 is greater than t, if a delay start time is between <NUM>*t and t, the time to stay at high level is [T1-<NUM>*t, T1); and if a delay start time is between <NUM> and <NUM>*t, the time to stay at high level is T1. The low-side driver unit maintains an on state within the set delay time, and the relay maintains the original on state. When receiving a relay switch-off signal, the control module <NUM> outputs a low-level drive signal to the low-side driver unit, outputs a low-level control signal <NUM> to the port R of the delay component, and outputs a low-level control signal <NUM> to the port B of the delay component, and the low-side driver unit is switched off. When the control module <NUM> is being reset, the output of the control module <NUM> is in a high-impedance state, and the port B of the delay component is still at a low level. Because there is the first pull-up unit, a state of the port R of the delay component changes from a low level to a high level, output of the port Q is still at a low level, the state of the low-side driver unit does not change, and the relay is not accidentally switched on.

In some embodiments, the drive circuit further includes a first diode and a second diode, the delay module <NUM> is connected to the control terminal of the low-side driver module <NUM> through the first diode, and the control module <NUM> is connected to the control terminal of the low-side driver module <NUM> through the second diode.

In some embodiments, the first diode and the second diode are diodes. It is assumed that the load <NUM> is a relay and the low-side driver unit is a type-N transistor, the first level and the second level are high levels, the third level and the fourth level are low levels, and the edge signal is the falling edge signal. <FIG> is a schematic circuit diagram of the drive circuit. V1 represents the drive power supply, J1 represents the relay, M1 represents the low-side driver unit, Y1 represents the delay component, R represents the first input terminal of the delay component, B represents the second input terminal of the delay component, Q represents the output terminal of the delay component, V2 represents a first signal terminal of the pull-up power supply, and RT represents a first pull-up resistor, D1 represents the first diode, and D2 represents the second diode. The control signal <NUM> may be a constant-level signal or a pulse width modulation signal.

It is worth mentioning that, the delay module <NUM> is connected to the control terminal of the low-side driver module <NUM> through the first diode, and the control module <NUM> is connected to the control terminal of the low-side driver module <NUM> through the second diode, so that the drive signal from the control module <NUM> and the output signal from the delay module <NUM> compete for the power supply, and the low-side driver unit can be switched on when either signal meets the requirement.

In the first example, the drive circuit is configured to drive a load, and the load is grounded through the low-side driver module <NUM>; and the low-side driver module <NUM> includes a first low-side driver unit and a second low-side driver unit, where a first terminal of the first low-side driver unit and a first terminal of the second low-side driver unit are both connected to a second terminal of the load <NUM>, a second terminal of the first low-side driver unit and a second terminal of the second low-side driver unit are grounded, the control module <NUM> is connected to a control terminal of the first low-side driver unit, and an output terminal of the delay module <NUM> is connected to a control terminal of the second low-side driver unit. In some embodiments, the control module <NUM> may be configured to: after detecting a switch-on signal, output the drive signal of the second level or a second pulse width modulation PWM control signal to the first low-side driver unit, output a control signal of the first level or the third level to the first controlled terminal of the delay module <NUM>, and output a control signal of a fifth level or a third pulse width modulation PWM control signal to the second controlled terminal of the delay module <NUM>; and after detecting a switch-off signal, output the drive signal of the fourth level to the first low-side driver unit, and output a control signal of the third level to the first controlled terminal and the second controlled terminal of the delay module <NUM>, where a period of the third pulse width modulation PWM control signal is less than the preset duration; and when the edge signal is a rising edge signal, the fifth level is a low level, or when the edge signal is a falling edge signal, the fifth level is a high level.

In some embodiments, after detecting the switch-on signal, the control module <NUM> outputs the first level to the first controlled terminal of the delay module <NUM>, to ensure that when the control module <NUM> is being reset, the delay module <NUM> outputs a delay signal of the second level when the edge signal is detected at the second controlled terminal, so that the relay maintains an on state.

It is assumed that the load <NUM> is a relay and the first low-side driver unit and the second low-side driver unit are type-N transistors, the first level and the second level are high levels, the third level and the fourth level are low levels, and the edge signal is the falling edge signal. <FIG> is a schematic circuit diagram of the drive circuit. V1 represents the drive power supply, J1 represents the relay, M1 represents the first low-side driver unit, M2 represents the second low-side driver unit, Y1 represents the delay component, R represents the first input terminal of the delay component, B represents the second input terminal of the delay component, Q represents the output terminal of the delay component, V2 represents a first signal terminal of the pull-up power supply, and RT represents a first pull-up resistor. The control signal <NUM> may be a constant-level signal or a pulse width modulation signal.

It is assumed that the control signal <NUM> is the constant-level signal, and the working principle of the drive circuit is as follows: When receiving a relay switch-on signal, the control module <NUM> outputs a PWM drive signal (second pulse width modulation PWM drive signal) to the control terminal of the first low-side driver unit, outputs a high-level control signal <NUM> to the port R of the delay component, and outputs a high-level control signal <NUM> to the port B of the delay component. Because there is no falling edge, a low level is output at the port Q of the delay component, and the first low-side driver unit is switched on. That is, when the control module <NUM> works normally and the relay is on, the first low-side driver unit is switched on, and in this case, the second low-side driver unit is switched off. When the control module <NUM> is being reset, the drive signal of the first low-side driver unit is pulled down, the control signal <NUM> is pulled down, and the control signal <NUM> is pulled up. The port Q of the delay component outputs a high-level pulse, so that the second low-side driver unit is switched on. In this case, the first low-side driver unit is switched off, and the relay is not switched off within the set delay time. At the end of the reset (work resumed), the control module <NUM> sends a PWM drive signal, so that the first low-side driver unit is connected. In some embodiments, the control signal <NUM> is first pulled down and then pulled up, and the control signal <NUM> is pulled up, so that the second low-side driver unit is switched off and returns to a normal working state of the low-side driver module <NUM>. When receiving a relay switch-off signal, the control module <NUM> outputs a low-level drive signal to the control terminal of the first low-side driver unit, outputs a low-level control signal <NUM> to the port R of the delay component, and outputs a low-level control signal <NUM> to the port B of the delay component. In this case, the port Q of the delay component outputs a low level, and the relay is off. When the control module <NUM> is being reset, the drive signal of the first low-side driver unit is continuously at a low level, the control signal <NUM> is pulled up because of the first pull-up resistor, the control signal <NUM> is continuously at a low level, output of the port Q of the delay component is continuously at a low level, and the relay maintains an off state and is not accidentally switched on.

It should be noted that a person skilled in the art can understand that, for a PWM-driven relay, the PWM drive signal is output to the first low-side driver unit, and when the control module <NUM> is being reset, the relay is driven through the high level instead of the PWM. Therefore, when designing the delay time (preset duration) of the delay component, a person skilled in the art may consider whether a coil of the relay can normally work within the preset duration, in order to avoid burn-down of the coil caused by a coil current that is excessively large and lasts for excessively long time when the relay is driven through a high level. Therefore, the preset duration needs to be greater than the reset time of the control module <NUM>, to ensure that when the control module <NUM> is being reset, the relay maintains a state before the control module <NUM> is reset; and the preset duration needs to be less than duration of high-level driving that can be tolerated by the relay, to protect the relay. An instruction sequence after the control module <NUM> completes the reset should also be considered. If delay between an instruction for controlling the first low-side driver unit and an instruction for controlling the second low-side driver unit is very long or even longer than action time of the relay, the first low-side driver unit needs to be first connected, and then the second low-side driver unit is disconnected. If the delay is very short and shorter than the action time of the relay, the sequence is not limited.

It is worth mentioning that in this embodiment, two low-side driver units are disposed. The first low-side driver unit is switched on or off based on the PWM drive signal output by the control module <NUM>, the second low-side driver unit is switched on or off based on the delay signal output by the delay module <NUM>, and therefore, when the control module <NUM> is being reset, if the relay is switched from PWM control to high-level control, a large current generated by the relay passes through the second low-side driver unit instead of the first low-side driver unit, so that a large current in the circuit does not affect service life of the first low-side driver unit, thereby ensuring safety of a vehicle during normal operation of the control module <NUM>.

In some embodiments, to prevent the large current from affecting service life and performance of the second low-side driver unit, a person skilled in the art can select a chip with a larger operating current as the second low-side driver unit.

In a second example, the delay unit includes N cascaded delay components; and first input terminals of all the delay components are mutually connected, where a joint serves as the first controlled terminal of the delay unit, a second input terminal of a <NUM>st delay component is connected to the second controlled terminal of the delay unit, a second input terminal of an (i+<NUM>)th delay component is connected to an output terminal of an ith delay component, and an output terminal of an Nth delay component serves as the output terminal of the delay unit, where <NUM>≤i<N, and N is an integer greater than <NUM>.

It is worth mentioning that the delay unit is obtained by cascading a plurality of delay components, and total delay time of the delay unit is equal to a sum of delay time of the delay components, thereby prolonging the delay time. In addition, in some embodiments, the delay components can have different delay time resolution. Integrating the delay components with the different delay time resolution can ensure that the delay unit can meet more delay time requirements, thereby improving delay precision. For example, when delay of <NUM> seconds is required, to improve precision, a delay component with resolution of seconds and a delay component with millisecond resolution may be selected.

In the second example, the low-side driver module <NUM> includes a first low-side driver unit and a second low-side driver unit, where a first terminal of the first low-side driver unit and a first terminal of the second low-side driver unit are both connected to a second terminal of the load <NUM>, a second terminal of the first low-side driver unit and a second terminal of the second low-side driver unit are grounded, the control module <NUM> is connected to a control terminal of the first low-side driver unit, and the delay module <NUM> is connected to a control terminal of the second low-side driver unit. In some embodiments, the control module <NUM> may be configured to: after detecting a switch-on signal, output the drive signal of the second level or a second pulse width modulation PWM control signal to the first low-side driver unit, output a control signal of the first level or the third level to the first controlled terminal of the delay module <NUM>, and output a control signal of a fifth level or a third pulse width modulation PWM control signal to the second controlled terminal of the delay module <NUM>; and after detecting a switch-off signal, output the drive signal of the fourth level to the first low-side driver unit, and output a control signal of the third level to the first controlled terminal and the second controlled terminal of the delay module <NUM>, where a period of the third pulse width modulation PWM control signal is less than the preset duration; and when the edge signal is a rising edge signal, the fifth level is a low level, or when the edge signal is a falling edge signal, the fifth level is a high level.

It is assumed that N is equal to <NUM>, the load <NUM> is a relay and the first low-side driver unit and the second low-side driver unit are type-N transistors, the first level and the second level are high levels, the third level and the fourth level are low levels, and the edge signal is the falling edge signal. <FIG> is a schematic circuit diagram of the drive circuit. V1 represents the drive power supply, J1 represents the relay, M1 represents the first low-side driver unit, M2 represents the second low-side driver unit, Y1 represents the first delay component, Y2 represents the second delay component, R represents the first input terminal, B represents the second input terminal, Q represents the output terminal, and P represents the joint (that is, the first controlled terminal) between the first delay component and the second delay component, the terminal B of Y1 is the second controlled terminal, V2 represents a first signal terminal of the pull-up power supply, and RT represents a first pull-up resistor. The control signal <NUM> may be a constant-level signal or a pulse width modulation signal.

It is assumed that the control signal <NUM> is the PWM control signal (third pulse width modulation PWM control signal), the working principle of the drive circuit is as follows: When receiving a relay switch-on signal, the control module <NUM> outputs a PWM drive signal (second pulse width modulation PWM drive signal) to the control terminal of the first low-side driver unit, outputs a high-level control signal <NUM> to the port R of the first delay component and the port R of the second delay component, and outputs a PWM control signal <NUM> (third pulse width modulation PWM control signal) to the port B of the first delay component. In this case, a high level is output at the port Q of the first delay component, a low level is output at the port Q of the second delay component, and the first low-side driver unit is switched on. That is, when the control module <NUM> works normally and the relay is connected, the first low-side driver unit is conductive. When the control module <NUM> is being reset, a drive signal of the first low-side driver unit is pulled down, and the port Q of the first delay component is switched from a high level to a low level after staying at high level for a period of time, and the time to stay at high level is [T1-t/<NUM>, T1). In this case, for a falling edge occurring to the port B of the second delay component, the port Q of the second delay component immediately outputs a high level. During the duration [T1-t/<NUM>, T1), the port Q of the second delay component is still at a low level. Because mechanical action time of the relay is on the order of milliseconds, values of T1 and t/<NUM> are appropriately selected, so that the relay is not switched off when the control module <NUM> outputs a low level. Total delay time of the delay module <NUM> is a sum of delay time of the first delay component and the second delay component, that is, (T2+T1-t/<NUM>, T2+T1). T1 is the delay time of the first delay component, t is a period of the PWM control signal, and T2 is the delay time of the second delay component. After completing the reset, the control module <NUM> may send a PWM drive signal, so that the first low-side driver unit is connected. In addition, the control signal <NUM> is first pulled down and then pulled up, and a PWM control signal <NUM> is output, so that the second low-side driver unit is switched off and returns to a normal working state of the low-side driver module. When receiving a relay switch-off signal, the control module <NUM> outputs a low-level drive signal to the control terminal of the first low-side driver unit, so that the first low-side driver unit is switched off, and the control module outputs the low-level control signal <NUM> to the port R of the first delay component and the port R of the second delay component, and outputs the low-level control signal <NUM> to the port B of the first delay component, the port Q of the first delay component outputs a low level, a low level is output at the port Q of the second delay component, and the second low-side driver unit is switched off. When the control module <NUM> is being reset, the drive signal of the first low-side driver unit is switched to a low level, the control signal <NUM> is pulled up because of the first pull-up resistor, the control signal <NUM> is continuously at a low level, and outputs of both the port Q of the first delay component and the port Q of the second delay component are at a low level. The relay maintains an off state and is not accidentally switched on.

It is worth mentioning that controlling the first low-side driver unit with the PWM drive signal can adjust the on time of the low-side driver module by changing a duty ratio of the PWM drive signal, thereby adjusting a current of the load terminal.

It is worth mentioning that a plurality of delay components form the delay unit, thereby prolonging the delay time.

In some embodiments, the delay component is a monostable flip-flop.

It should be noted that a person skilled in the art can understand that in practical applications, another device may be selected as the delay component. A circuit form of the delay component is not limited in this application.

It should be noted that in <FIG>, an example in which an edge signal is a falling edge signal is used to illustrate a circuit structure of a drive circuit. In practical applications, the edge signal may be a rising edge signal. When the edge signal is a rising edge signal, <FIG> show a circuit structure of a drive circuit. V1 represents the drive power supply, J1 represents the relay, M1 represents the low-side driver unit, Y1 represents the delay component, R represents the first input terminal of the delay component, A represents the second input terminal of the delay component, Q represents the output terminal of the delay component, V2 represents a first signal terminal of the pull-up power supply, RT represents the first pull-up resistor, which constitutes the first pull-up unit, V3 represents a second signal terminal of the pull-up power supply, and RD represents the second pull-up resistor, which constitutes the second pull-up unit. Herein, a working principle of a circuit structure shown in <FIG> is briefly described. A working principle in <FIG> and <FIG> may be implemented with reference to related descriptions of the working principle when the edge signal is the falling edge and the working principle in <FIG>. In <FIG>, when the edge signal is a rising edge signal, if the control module <NUM> receives a relay switch-on signal, the control module <NUM> outputs a high-level drive signal and a high-level control signal <NUM>, or the control module <NUM> outputs a low-level control signal <NUM> or a PWM control signal <NUM>. When the control module <NUM> is being reset, the port R continuously stays at high level under action of the first pull-up unit; and the port A is changed from a low level to a high level because the output of the control module <NUM> is in a high-impedance state and there is a second pull-up unit. That is, a rising edge appears. Therefore, a high level is output at the port Q of the delay component. If the control module <NUM> receives a relay switch-off signal, the control module <NUM> outputs a low-level drive signal to the control terminal of the low-side driver module <NUM>, outputs a low-level control signal <NUM> to the port R of the delay component, and outputs a high-level control signal <NUM> to the port A of the delay component. When the control module <NUM> is being reset, the port R of the delay component is pulled up, the port A of the delay component stays at high level without a rising edge, and therefore, a low level is output at the port Q of the delay component, and the relay maintains an off state.

It should be noted that the foregoing description is only used as an example for illusion and does not impose any limitation on the technical solutions in the embodiments of this application.

Compared with the prior art, based on the drive circuit of the load provided in this application, when the control module <NUM> is being reset, the delay module <NUM> can output a delay signal to the low-side driver module, so that the low-side driver module maintains a state before the control module <NUM> is reset, thereby avoiding safety hazards caused by a state change of the low-side driver module due to the reset of the control module <NUM>.

A first embodiment in the embodiments of this application relates to a drive circuit. This embodiment is obtained by making a further improvement on the basis of the above embodiment. The specific improvement is as follows: A check module is added to the drive circuit. The following uses an example to describe the check module. For structures and functions of other modules, refer to the related content in the above embodiment.

Specifically, <FIG> is a schematic structural diagram of a drive circuit. The drive circuit is configured to drive a load <NUM>, and the load <NUM> is grounded through a low-side driver module <NUM>. The drive circuit also includes a check module <NUM>, an input terminal of the check module <NUM> is connected to a joint between the low-side driver module <NUM> and the load <NUM>, and an output terminal of the check module <NUM> is connected to the control module <NUM>. The control module <NUM> is further configured to: at the end of the reset (work resumed), output the drive signal based on a check signal input by the check module <NUM> or load state data stored in a storage module, to control the low-side driver module <NUM>.

The following uses an example in which the load <NUM> is a relay to illustrate a function of the check module <NUM> and a working manner of the control module <NUM>.

In an embodiment, after completing the reset, the control module <NUM> can determine a drive signal based on a relay state stored in an internal register of the control module <NUM> (before the reset, the control module can determine a relay state based on the check signal input by the check module <NUM>). It is assumed that the low-side driver unit is a type-N transistor, if the relay is on, the control module outputs a high-level drive signal, a high-level control signal <NUM>, and a high-level control signal <NUM>, to maintain the on state of the relay; and if the relay is off, the control module outputs a low-level drive signal, a low-level control signal <NUM>, and a low-level control signal <NUM> to maintain the off state of the relay.

In another embodiment, after completing the reset, the control module <NUM> determines a current state of the relay based on the check signal input by the check module <NUM>. If the relay is on, the control module <NUM> outputs a high-level drive signal, a high-level control signal <NUM>, and a high-level control signal <NUM>, to maintain the on state of the relay; and if the relay is off, the control module <NUM> outputs a low-level drive signal, a low-level control signal <NUM>, and a low-level control signal <NUM>, to maintain the off state of the relay.

In an embodiment, the check module <NUM> includes a voltage divider sub-module and a filter sub-module, a first terminal of the voltage divider sub-module serves as the input terminal of the check module <NUM>, a second terminal of the voltage divider sub-module is connected to a first terminal of the filter sub-module, and a second terminal of the filter sub-module serves as the output terminal of the check module <NUM>.

In an embodiment, <FIG> is a circuit diagram of a check module <NUM>. A voltage divider sub-module includes a first voltage divider resistor R1 and a second voltage divider resistor R2. A first terminal of the first voltage divider resistor R1 serves as a first terminal of the voltage divider sub-module, a second terminal of the first voltage divider resistor R1 is connected to a first terminal of the second voltage divider resistor R2, a second terminal of the second voltage divider resistor R2 is grounded, and a node between the second terminal of the first voltage divider resistor R1 and the first terminal of the second voltage divider resistor R2 serves as a second terminal of the voltage divider sub-module. The filter sub-module includes a filter resistor R3 and a filter capacitor C. A first terminal of the filter resistor R3 serves as a first terminal of the filter sub-module. A second terminal of the filter resistor R3 is connected to a first terminal of the filter capacitor C. A second terminal of the filter capacitor C is grounded, and a node between the second terminal of the filter resistor R3 and the first terminal of the filter capacitor C serves as a second terminal of the filter sub-module. <FIG> is a schematic circuit diagram of a drive circuit obtained after a check module <NUM> is added to the circuit structure of the delay unit shown in <FIG>. Meaning of each letter can be understood with reference to <FIG> and <FIG> in the above embodiment. With reference to the above embodiment and <FIG>, it can be seen that if the load <NUM> is a relay, when the check signal is at a high level, at the end of the reset (work resumed), the control module <NUM> outputs a high-level drive signal, a high-level control signal <NUM>, and a high-level control signal <NUM>, to control the relay to maintain an on state; and when the check signal is at a low level, at the end of the reset (work resumed), the control module <NUM> outputs a low-level drive signal, a low-level control signal <NUM> and a control signal <NUM>, to keep the relay off.

It should be noted that a person skilled in the art can understand that in practical applications, the check module <NUM> may alternatively use another detectable circuit form. A circuit structure of the check module <NUM> is not limited in this embodiment.

It should be noted that a person skilled in the art can understand that in <FIG>, an example in which an input terminal of the check module <NUM> is connected to a joint between the low-side driver module <NUM> and the load <NUM> is used to illustrate a connection relationship between the check module <NUM> and another module. In practical applications, the input terminal of the check module <NUM> may alternatively be connected to a control terminal of the low-side driver module <NUM>, and the control module <NUM> determines a level of the drive signal output after the reset based on an electrical signal detected by the check module <NUM>. It should be noted that in <FIG>, an example in which an edge signal is a falling edge signal is used to show a connection relationship among the check module <NUM>, the control module <NUM>, the low-side driver module <NUM>, and the delay module <NUM>. In practical applications, when the edge signal is a rising edge signal, a connection relationship among the check module <NUM>, the control module <NUM>, the low-side driver module <NUM>, and the delay module <NUM> is approximately the same as that in a case that the edge signal is the falling edge signal. A person skilled in the art can perform implementation with reference to <FIG>.

It should be noted that a person skilled in the art can understand that in this embodiment, the control module <NUM> determines a state of the load <NUM> after the reset based on the check signal of the check module <NUM>. In practical applications, the control module <NUM> may alternatively output the drive signal based on load state data stored in a storage module at the end of the reset (work resumed). For example, after receiving a switch-on instruction or a switch-off instruction, the control module <NUM> writes a relevant instruction into the register. After the reset, the control module <NUM> reads the data from the register to determine the state of the load <NUM> after the reset. The control module <NUM> may alternatively determine the state of the load <NUM> based on the check signal and the load state data stored in the storage module. If the check signal or the load state data indicates that the load <NUM> is off, a signal for keeping the load <NUM> off is output. A method for the control module <NUM> to keep the state of the load <NUM> at the end of the reset (work resumed) is not limited in this embodiment.

It should be noted that the foregoing description is only used as an example for illusion and does not impose any limitation on the technical solutions of this application.

Compared with the prior art, based on the drive circuit of the load provided in this embodiment, when the control module is being reset, the delay module can output a delay signal to the low-side driver module, so that the low-side driver module maintains a state before the control module is reset, thereby avoiding safety hazards caused by a state change of the low-side driver module due to the reset of the control module. When in a working state, the control module can output a drive signal to control the low-side driver module to switch on or off, the drive signal can compete with the output signal of the delay module for power supply, and the low-side driver unit can be switched on when either signal meets the requirement. When the control module is being reset, a delay function of the entire circuit is implemented through a separate delay module, thereby simplifying drive logic of the control module and a circuit design. In addition, there is also a check module in the drive circuit, and therefore, the control module can directly output the control signal to the low-side driver module based on the check signal at the end of the reset (work resumed), so that the low-side driver module maintains the state before the reset, thereby maintaining the load in the state before the reset is completed.

Claim 1:
A drive circuit for driving a load (<NUM>), wherein the drive circuit comprises a low-side driver module (<NUM>) and a delay module (<NUM>), and the load (<NUM>) is grounded through the low-side driver module (<NUM>);
the delay module (<NUM>) is configured to output a delay signal of preset duration to the low-side driver module (<NUM>) in a case that a control module (<NUM>) is being reset, wherein the control module (<NUM>) is configured to control an on/off state of the low-side driver module (<NUM>); and
the low-side driver module (<NUM>) is configured to: work in a first on/off state before the control module is reset, and maintain, according to the delay signal of preset duration, the first on/off state within the preset duration after the control module is reset,
characterised in that
the delay module (<NUM>) comprises a delay unit and a first pull-up unit; a first controlled terminal of the delay unit is connected to both the first pull-up unit and a first output terminal of the control module (<NUM>), a second controlled terminal of the delay unit is connected to a second output terminal of the control module (<NUM>), and an output terminal of the delay unit is connected to a control terminal of the low-side driver module (<NUM>); and
the delay unit is configured to: when an electrical signal of a first level is detected at the first controlled terminal and an edge signal is detected at the second controlled terminal, output a delay signal of a second level; and when an electrical signal of a third level is detected at the first controlled terminal, output a delay signal of a fourth level;
wherein the fourth level is a reverse level of the second level, the third level is a reverse level of the first level, and the low-side driver module (<NUM>) is switched on when receiving an electrical signal of the second level and switched off when receiving an electrical signal of the fourth level.