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CN118554928B - High-side switch circuit - Google Patents

High-side switch circuit Download PDF

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Publication number
CN118554928B
CN118554928B CN202411001906.5A CN202411001906A CN118554928B CN 118554928 B CN118554928 B CN 118554928B CN 202411001906 A CN202411001906 A CN 202411001906A CN 118554928 B CN118554928 B CN 118554928B
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CN
China
Prior art keywords
temperature protection
voltage
unit
power tube
protection threshold
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Application number
CN202411001906.5A
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Chinese (zh)
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CN118554928A (en
Inventor
李�瑞
陈劲泉
丁鹏菲
秦松
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Rongxin Electronic Technology Wuxi Co ltd
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Rongxin Electronic Technology Wuxi Co ltd
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Priority to CN202411001906.5A priority Critical patent/CN118554928B/en
Publication of CN118554928A publication Critical patent/CN118554928A/en
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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/08—Modifications for protecting switching circuit against overcurrent or overvoltage
    • H03K17/081—Modifications for protecting switching circuit against overcurrent or overvoltage without feedback from the output circuit to the control circuit
    • H03K17/0812—Modifications for protecting switching circuit against overcurrent or overvoltage without feedback from the output circuit to the control circuit by measures taken in the control circuit
    • H03K17/08122—Modifications for protecting switching circuit against overcurrent or overvoltage without feedback from the output circuit to the control circuit by measures taken in the control circuit in field-effect transistor switches
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H5/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection
    • H02H5/04—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to abnormal temperature
    • H02H5/047—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to abnormal temperature using a temperature responsive switch
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/22—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for distribution gear, e.g. bus-bar systems; for switching devices
    • H02H7/222—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for distribution gear, e.g. bus-bar systems; for switching devices for switches
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
    • H03K17/56—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices
    • H03K17/687—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being field-effect transistors
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/08—Modifications for protecting switching circuit against overcurrent or overvoltage
    • H03K2017/0806—Modifications for protecting switching circuit against overcurrent or overvoltage against excessive temperature

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Abstract

A high-side switching circuit, comprising: a target current generation unit adapted to generate and output a target current; the first comparison unit outputs a first comparison result of the output voltage of the high-side switch circuit and the first voltage; a control unit outputting a first control signal based on a first comparison result; when the temperature protection trigger signal is received, the power tube is controlled to be disconnected, and when the temperature protection trigger signal is not received, the power tube is controlled to be connected; controlling the current of the power tube when being conducted to be equal to the target current; the protection threshold generating unit is suitable for outputting a first temperature protection threshold or a second temperature protection threshold as a target temperature protection threshold based on the first control signal; and the temperature protection unit is suitable for responding to the fact that the real-time temperature of the power tube is larger than the target temperature protection threshold value and outputting a temperature protection trigger signal. By the scheme, the reliability of the high-side switch circuit in a capacitor charging scene can be improved, and meanwhile the steady-state load capacity of the high-side switch circuit is not affected.

Description

High-side switch circuit
Technical Field
The invention relates to the technical field of electronic circuits, in particular to a high-side switch circuit.
Background
The high-side switch circuit provides a current and voltage path to a load by controlling the conduction of an internal power tube (MOSFET tube). In power distribution applications, the load of the high-side switching circuit may be a controller in a vehicle. The input of the controller typically has a large capacitance. When a starting signal for starting the controller is received, the high-side switch circuit is turned on, the power supply charges the capacitor of the controller through the high-side switch circuit until the voltage at two ends of the capacitor reaches the working voltage of the controller, and the controller is started.
In the charging process of the capacitor, the high-side switch circuit detects the temperature of the power tube in real time. If the high-side switch circuit detects that the temperature of the power tube reaches a temperature protection threshold value, the power tube is controlled to be disconnected; and when the temperature of the power tube is detected to be lower than the temperature protection threshold value, controlling the power tube to be conducted again. And the process is repeated until the capacitor is charged.
In some special scenarios, such as when a load is shorted, the power tube can be continuously switched between on and off, and the power tube is subjected to high-low temperature cycle, so that the reliability of the high-side switch circuit is poor. In order to improve the reliability of the high-side switch circuit, one solution is to reduce the temperature protection threshold to reduce the real-time temperature of the power tube. But the above approach reduces the steady-state load capability of the high-side switching circuit.
Disclosure of Invention
The invention aims at providing a high-side switch circuit, which can improve the reliability of the high-side switch circuit and can not influence the steady-state load carrying capacity of the high-side switch circuit.
In a first aspect, the present invention provides a high-side switching circuit comprising: the device comprises a target current generating unit, a first comparing unit, a power tube, a control unit, a protection threshold generating unit and a temperature protection unit, wherein: the target current generating unit is suitable for generating and outputting a target current; the first input end of the first comparison unit inputs the output voltage of the high-side switch circuit, the second input end of the first comparison unit inputs the first voltage, and the output end of the first comparison unit outputs a first comparison result; the first voltage is the difference between the input voltage of the high-side switch circuit and a first voltage threshold; the control unit is suitable for outputting a first control signal to the protection threshold generating unit based on the first comparison result; and controlling the power tube to be disconnected when the temperature protection trigger signal is received, and controlling the power tube to be connected when the temperature protection trigger signal is not received; and controlling the working current of the power tube when the power tube is conducted to be equal to the target current; the protection threshold generating unit is suitable for outputting a target temperature protection threshold based on the first control signal; the target temperature protection threshold is a first temperature protection threshold or a second temperature protection threshold, and the first temperature protection threshold is larger than the second temperature protection threshold; the temperature protection unit is suitable for responding to the fact that the real-time temperature of the power tube is larger than the target temperature protection threshold value, and outputting the temperature protection trigger signal.
Based on the magnitude relation between the output voltage of the high-side switch circuit and the first voltage, a corresponding target temperature protection threshold value is selected. The output voltage of the high-side switch circuit is the voltage at two ends of the load capacitor. When the voltage at two ends of the load capacitor is smaller than the first voltage, a smaller target temperature protection threshold value can be selected, so that the reliability of the high-side switch circuit in a load capacitor charging scene can be improved; when the voltage at two ends of the load capacitor reaches the first voltage, a larger target temperature protection threshold value is selected, so that the steady-state load carrying capacity of the high-side switch circuit is not affected. And the control unit controls the working current when the power tube is conducted to be equal to the target current. Thus, the operating current of the power tube can be adjusted by adjusting the magnitude of the target current. Therefore, a user can adjust the size of the target current according to the requirements of voltage overshoot, wire harness current capability and the like, so that the damage of components caused by the voltage overshoot and the heating of the wire harness caused by poor wire harness current capability are avoided.
Optionally, when the output voltage is greater than the first voltage, the target temperature protection threshold is the first temperature protection threshold; and when the output voltage is smaller than the first voltage, the target temperature protection threshold is the second temperature protection threshold.
Optionally, the high-side switch circuit further includes: the short circuit detection unit is suitable for outputting a short circuit signal to the control unit when detecting that the output voltage is smaller than a preset short circuit voltage threshold value; the control unit is further adapted to enter a locking state after receiving the short circuit signal; and when the control unit is in the locking state, the power tube is controlled to be disconnected.
And when the short circuit detection unit detects that the output voltage of the high-side switch circuit is smaller than a preset short circuit voltage threshold value, outputting a short circuit signal to the control unit. The control unit can control the power tube to be continuously disconnected. Therefore, when the high-side switch circuit is short-circuited, the power tube can be timely protected.
Optionally, the short circuit detection unit includes: a second comparing unit and a short-circuit voltage threshold generating unit, wherein: the first input end of the second comparison unit is coupled with the output end of the high-side switch circuit, and the output end of the second comparison unit is coupled with the control unit; the short-circuit voltage threshold generating unit is suitable for generating the short-circuit voltage threshold and outputting the short-circuit voltage threshold to the second input end of the second comparing unit.
Optionally, the control unit is further adapted to output an enable signal to the short circuit detection unit to trigger the short circuit detection unit to enable after the enable time reaches the first time; and closing the short circuit detection unit after the enabling time length reaches a fourth time length; and before the enabling time reaches the fourth time, a load capacitor coupled with the high-side switch circuit is charged.
Optionally, the control unit is further adapted to control the power tube to be continuously disconnected if the temperature protection trigger signal is received after the enabling duration reaches the fourth duration.
Optionally, the control unit is adapted to control the power tube to be disconnected after receiving the short-circuit signal before the enabling time period does not reach the fourth time period, and control the power tube to be disconnected again after waiting for the second time period; and after the power tube is continuously conducted for N times, the short circuit signals are received, and the power tube enters the locking state; n is an integer and N is more than or equal to 2; the short circuit detection unit is further adapted to re-detect whether the output voltage is smaller than the short circuit voltage threshold value after the power tube is re-turned on for a third period of time, and re-output the short circuit signal to the control unit when the output voltage is smaller than the short circuit voltage threshold value.
Optionally, the protection threshold generating unit includes: a first protection threshold generating unit, a second protection threshold generating unit, and a switching unit, wherein: the first protection threshold generating unit is suitable for generating the first temperature protection threshold; the second protection threshold generating unit is suitable for generating the second temperature protection threshold; the switching unit is suitable for outputting a first temperature protection threshold value based on the first control signal; or outputting a second temperature protection threshold.
Drawings
FIG. 1 is a schematic diagram of a high-side switch circuit according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of another high-side switching circuit according to an embodiment of the present invention;
FIG. 3 is a waveform diagram illustrating operation of a high-side switching circuit according to an embodiment of the present invention;
Fig. 4 is a schematic waveform diagram of a short circuit of a high-side switch circuit according to an embodiment of the present invention.
Detailed Description
In order to improve the reliability of the high-side switch circuit, a dynamic temperature protection circuit is provided in the prior art. When the real-time temperature of the power tube reaches the temperature protection threshold, the high-side switch circuit controls the power tube to be disconnected. When the temperature of the power tube is reduced to a certain value, the high-side switch circuit controls the power tube to be conducted again. And thus, the process is repeated until the voltage at the two ends of the capacitor reaches the working voltage of the controller.
However, in some special scenarios, such as when a load is shorted, the power tube may continuously switch between on and off, and undergo a high-low temperature cycle, resulting in poor reliability of the high-side switching circuit. In order to improve the reliability of the high-side switch circuit, one solution is to reduce the temperature protection threshold to reduce the real-time temperature of the power tube. However, in the above scheme, under the heavy current working scene, the temperature protection is triggered easily, and the steady-state load capacity of the high-side switch circuit is reduced.
In the embodiment of the invention, the corresponding target temperature protection threshold value is selected based on the magnitude relation between the output voltage of the high-side switch circuit and the first voltage. When the voltage at two ends of the capacitor is smaller than the first voltage, a smaller target temperature protection threshold value can be selected, so that the reliability of the high-side switch circuit can be improved; when the voltage at two ends of the capacitor reaches the first voltage, a larger target temperature protection threshold value is selected, so that the steady-state load carrying capacity of the high-side switch circuit is not affected. And the control unit controls the working current when the power tube is conducted to be equal to the target current. Thus, the operating current of the power tube can be adjusted by adjusting the magnitude of the target current. Therefore, a user can adjust the size of the target current according to the requirements of voltage overshoot, wire harness current capability and the like, so that the damage of components caused by the voltage overshoot and the heating of the wire harness caused by poor wire harness current capability are avoided.
In addition, the high-side switching circuit may further include a short circuit detection unit. And when the short circuit detection unit detects that the output voltage of the high-side switch circuit is smaller than a preset short circuit voltage threshold value, outputting a short circuit signal to the control unit. The control unit can control the power tube to be continuously disconnected. Therefore, when the high-side switch circuit is short-circuited, the power tube can be timely protected, and the service life of the power tube can be prolonged.
In order to make the above objects, features and advantages of the present invention more comprehensible, embodiments accompanied with figures are described in detail below.
The embodiment of the invention provides a high-side switch circuit, which can comprise: the power supply comprises a target current generating unit, a first comparing unit, a power tube, a control unit, a protection threshold generating unit and a temperature protection unit, wherein:
a target current generation unit adapted to generate and output a target current;
The first input end of the first comparison unit can input the output voltage of the high-side switch circuit, the second input end of the first comparison unit can input the first voltage, and the output end of the first comparison unit can output a first comparison result; the first voltage may be a difference between an input voltage of the high-side switching circuit and a first voltage threshold;
The control unit may be coupled to an output terminal of the first comparing unit, receive the first comparison result output by the first comparing unit, and output a first control signal to the protection threshold generating unit based on the first comparison result; and controlling the power tube to be disconnected based on the received temperature protection trigger signal, and conducting when the temperature protection trigger signal is not received; the control unit is also suitable for configuring the working current of the power tube as target current when the power tube is conducted;
The protection threshold generating unit may be coupled to the control unit and receive the first control signal output by the control unit; the protection threshold generation unit may output the target temperature protection threshold based on the first control signal; the target temperature protection threshold is a first temperature protection threshold or a second temperature protection threshold, and the first temperature protection threshold is larger than the second temperature protection threshold;
the temperature protection unit can be coupled with the protection threshold generation unit and the control unit, acquires the real-time temperature of the power tube and the target temperature protection threshold, and outputs a temperature protection trigger signal to the control unit when the real-time temperature of the power tube is greater than the target temperature protection threshold.
It can be appreciated that if the real-time temperature of the power tube is less than the target temperature protection threshold, the temperature protection unit may not need to generate the temperature protection trigger signal. Or, if the real-time temperature of the power tube is smaller than the target temperature protection threshold, the temperature protection trigger signal disappears, and the control unit does not receive the temperature protection trigger signal.
Referring to fig. 1, a schematic diagram of a high-side switch circuit in an embodiment of the present invention is provided. The following is a detailed description with reference to fig. 1. The high-side switching circuit 10 includes a first comparing unit 11, a control unit 12, a protection threshold generating unit 13, a temperature protecting unit 14, and a target current generating unit 15.
The positive input terminal ("+") of the first comparing unit 11 is coupled to the output terminal OUT of the high-side switching circuit 10, and the negative input terminal ("-") of the first comparing unit 11 is coupled to the input first voltage V 1.
The first voltage V 1 may be provided by the first voltage source 16 as well as the external voltage source 21. The output voltage of the external voltage source 21 is Vs, and is input to the high-side switch circuit 10 via the IN port of the high-side switch circuit 10.
The voltage drop across the first voltage source 16 is V DS(TH), so the first voltage V 1 input to the inverting input of the first comparing unit 11 is V 1=VS-VDS(TH). The voltage input to the positive input terminal of the first comparing unit 11 is the output voltage V OUT of the high-side switch circuit 10.
The first comparing unit 11 compares V OUT with V S-VDS(TH). When V OUT＞VS-VDS(TH) is V OUT＞VS-VDS(TH), the first comparison result output by the first comparison unit 11 is a high level signal; when V OUT＜VS-VDS(TH) is set, the first comparison result output by the first comparison unit 11 is a low level signal.
In some embodiments, the first comparing unit 11 may be a comparator. In other embodiments, the first comparing unit 11 may be other circuit devices or circuit structures capable of implementing the comparing function.
In a specific implementation, the control unit 12 may include a plurality of communication interfaces, one of which is coupled to the output of the first comparing unit 11 and is capable of receiving the first comparison result. The control unit 12 further includes a communication interface communicating with the protection threshold generation unit 13, a communication interface communicating with the temperature protection unit 14, and the like.
The control unit 12 may learn the magnitude relation between the first voltage V 1 and the output voltage V OUT based on the level of the first comparison result. The control unit 12 may generate a first control signal corresponding to the first comparison result and output the first control signal to the protection threshold generation unit 13.
Specifically, when the first voltage V 1 is smaller than the output voltage V OUT, the control unit 12 may generate a first control signal of a first level and output the first control signal to the protection threshold generation unit 13. The protection threshold generation unit 13 receives the first control signal, and sets the target temperature protection threshold as the first temperature protection threshold.
When the first voltage V 1 is greater than the output voltage V OUT, the control unit 12 may generate the first control signal of the second level and output the first control signal to the protection threshold generation unit 13. The protection threshold generation unit 13 receives the first control signal, and sets the target temperature protection threshold as the second temperature protection threshold.
In an implementation, the first level is inverted from the second level. That is, if the first level is a low level, the second level is a high level; if the first level is high, the second level is low.
In a specific implementation, the first temperature protection threshold may be set to be greater than the second temperature protection threshold. The specific values of the first temperature protection threshold and the second temperature protection threshold can be preset according to experience values or according to user requirements.
That is, when the first voltage V 1 is smaller than the output voltage V OUT, a smaller first temperature protection threshold is adopted as the target temperature protection threshold; when the first voltage V 1 is greater than the output voltage V OUT, a larger second temperature protection threshold is employed as the target temperature protection threshold.
In a specific implementation, the temperature protection unit 14 may obtain the real-time temperature of the power tube MOSFET, and determine whether to output the temperature protection trigger signal based on the real-time temperature of the power tube MOSFET and the target temperature protection threshold.
In particular, the target temperature protection threshold may be adapted to characterize a temperature threshold that triggers temperature protection. If the real-time temperature of the power tube MOSFET exceeds the target temperature protection threshold, the temperature protection unit 14 may generate a temperature protection trigger signal and output the temperature protection trigger signal to the control unit 12. Accordingly, if the real-time temperature of the power tube MOSFET does not exceed the target temperature protection threshold, it can be determined that the current real-time temperature of the power tube MOSFET is within the normal range, and the temperature protection unit 14 does not need to generate the temperature protection trigger signal.
In a specific implementation, the temperature protection unit 14 may include a temperature sensor, through which the real-time temperature of the power tube MOSFET is obtained. The temperature sensor can be arranged at a position close to the surface of the power tube MOSFET so as to accurately acquire the real-time temperature of the power tube MOSFET. The temperature sensor may convert the real-time temperature into a corresponding voltage, with different voltages corresponding to different real-time temperatures. The target temperature protection threshold may be characterized in terms of a voltage. Thereby, the temperature protection unit 14 can compare the voltage of the temperature sensor with the target temperature protection threshold.
In some embodiments, the temperature coefficient of the temperature sensor may be a negative temperature coefficient, with the voltage of the temperature sensor decreasing as the real-time temperature increases. When the voltage of the temperature sensor is smaller than the target temperature protection threshold, it can be determined that the real-time temperature of the power tube MOSFET exceeds the temperature threshold, and the temperature protection unit 14 generates a temperature protection trigger signal and outputs the temperature protection trigger signal to the control unit 12.
In a specific implementation, the protection threshold generating unit 13 may include a first temperature protection threshold generating unit 131 and a second temperature protection threshold generating unit 132, where the first temperature protection threshold generating unit 131 is adapted to generate the first temperature protection threshold T SW(H), and the second temperature protection threshold generating unit 132 is adapted to generate the second temperature protection threshold T SW(L). The protection threshold generating unit 13 may further include a switching unit S, and a control terminal of the switching unit S may input the first control signal. When the control end of the switching unit S inputs a first control signal of a first level, the protection threshold generating unit 13 outputs a first temperature protection threshold, that is, the target temperature protection threshold is the first temperature protection threshold; when the control terminal of the switching unit S inputs the first control signal of the second level, the protection threshold generating unit 13 outputs the second temperature protection threshold, that is, the target temperature protection threshold is the second temperature protection threshold.
In some embodiments, the switching unit S may be a switching unit, a switching circuit, or the like capable of implementing a switching function or a switching function.
In practical applications, the output voltage V OUT of the output terminal OUT of the high-side switch circuit 10 gradually increases until the target voltage is reached during operation. Due to the presence of the power tube MOSFET, the target voltage is typically no greater than the input voltage V S of the high-side switching circuit 10.
In the embodiment of the invention, the first voltage V 1 is smaller than the target voltage. The target temperature protection threshold when the output voltage V OUT of the high-side switching circuit 10 is smaller than the first voltage V 1 is different from the target temperature protection threshold when the output voltage V OUT of the high-side switching circuit 10 is larger than the first voltage V 1. Thus, the output stability and reliability of the high-side switching circuit 10 can be improved, and the influence on the steady-state load capacity of the high-side switching circuit 10 can be avoided.
In some embodiments, the output OUT of the high-side switching circuit 10 is connected to a load controller, which includes a load capacitor. The target voltage is the working voltage of the load controller. In other words, when the voltage across the load capacitor reaches the target voltage, the load controller starts and starts operating.
As shown in fig. 1, a first terminal of the load capacitor C OUT is coupled to the output terminal OUT of the high-side switch circuit 10, and a second terminal of the load capacitor C OUT is grounded. The two ends of the load capacitor are connected with a load resistor R L in parallel. When the load controller is activated, the high-side switching circuit 10 starts to charge the load capacitor C OUT.
In implementations, the high-side switch circuit 10 may also include an enable EN port. When the enable port EN inputs a high level signal, the high side switch circuit 10 is enabled and starts to operate.
In an embodiment of the present invention, the target current generation unit 15 may be adapted to generate and output a target current to the control unit. The control unit may configure the operating current when the power tube MOSFET is turned on as the target current.
In a specific implementation, the magnitude of the target current is adjustable. That is, the magnitude of the target current output by the target current generation unit 15 may be adjusted based on a specific application scenario.
In some embodiments, the target current generating unit 15 may be configured by means of a software configuration to adjust the magnitude of the target current.
In other embodiments, the magnitude of the target current may be adjusted by means of hardware adjustment.
As shown in fig. 1, the high side switching circuit 10 is coupled to the adjustable resistor R CL through a CL port. The target current can be adjusted by adjusting the resistance value of the adjustable resistor R CL.
By providing the target current generation unit 15, the operating current of the power tube MOSFET can be configured. In an automobile application scene, corresponding target current can be set according to requirements such as voltage overshoot and wire harness current capability, so that damage to components caused by the voltage overshoot and wire harness heating caused by poor wire harness current capability are avoided.
In an embodiment of the present invention, the high-side switch circuit 10 may further include a short-circuit detection unit.
In an implementation, the control unit 12 may trigger the short circuit detection unit to enable when the enabling duration of the high-side switch circuit 10 reaches the first duration. Specifically, the control unit 12 may output an enable signal to the short-circuit detection unit when the enable period of the high-side switch circuit 10 reaches the first period. The short circuit detection unit starts to operate after receiving the enable signal, and detects whether the high-side switch circuit 10 is short-circuited.
The control unit 12 may output the off signal to the short detection unit when the enable period of the high-side switching circuit 10 reaches the fourth period. The short circuit detection unit is turned off after receiving the off signal, thereby reducing the power consumption of the high-side switching circuit 10.
That is, the short-circuit detection unit detects whether or not there is a short circuit in the high-side switch circuit 10 before reaching the fourth time period when the enable time period of the high-side switch circuit 10 reaches the first time period.
In a specific implementation, the first duration may be a preset duration or an empirical duration.
In some embodiments, the first time period may be greater than a fifth time period, which may be: when the high side switching circuit 10 is operating normally (i.e., no short circuit occurs), the voltage across the load capacitor reaches the short circuit voltage threshold for a desired period of time.
That is, when the high-side switch circuit 10 charges the load capacitor, if the high-side switch circuit 10 operates normally, the voltage value across the load capacitor must be greater than the short-circuit voltage threshold after the charging period reaches the first period. Therefore, if the charging time of the load capacitor reaches the first time, the voltage across the load capacitor is less than the short-circuit voltage threshold, so it can be determined that the high-side switch circuit 10 is shorted.
In implementations, the fourth duration may be associated with a target charge duration of the load capacitance, and the fourth duration may be greater than the target charge duration. The target charging time of the load capacitor is the charging time required by the voltage at the two ends of the load capacitor to reach the target voltage. When the voltage across the load capacitor reaches the target voltage,
In some embodiments, the target voltage may be less than the output voltage Vs of the external voltage source 21. The high-side switching circuit 10 may continue to charge the load capacitance until the voltage across the load capacitance reaches Vs. When the enable time period reaches the fourth time period, the voltage across the load capacitor may reach Vs.
That is, after the voltage across the load capacitor reaches Vs, the load capacitor charging is completed.
Referring to fig. 2, a schematic diagram of a structure of a high-side switch circuit according to an embodiment of the present invention is shown.
In a specific implementation, the short circuit detection unit may include: a second comparing unit 17 and a short-circuit voltage threshold generating unit 18, wherein:
A first input terminal of the second comparing unit 17 may be coupled to an output terminal of the high-side switching circuit 10, a second input terminal of the second comparing unit 17 may be coupled to an output terminal of the short-circuit voltage threshold generating unit, and an output terminal of the second comparing unit 17 is coupled to the control unit 12;
The short-circuit voltage threshold generating unit 18 is adapted to generate a short-circuit voltage threshold V OUT(SC) and to output the short-circuit voltage threshold V OUT(SC) to the second input of the second comparing unit 17.
The first input of the second comparing unit 17 may be a forward input and the second input of the second comparing unit 17 may be a reverse input. When the output voltage V OUT is less than the short-circuit voltage threshold voltage V OUT(SC), the second comparing unit 17 outputs a second comparison result of a low level; when the output voltage V OUT is greater than the short-circuit voltage threshold V OUT(SC), the second comparing unit 17 outputs a second comparison result of a high level.
In some embodiments, the short circuit signal output by the short circuit detection unit may be the second comparison result of the low level. The control unit 12 receives the second comparison result of the low level, i.e. enters a lock (latch) state. When the control unit 12 is in the locked state, the power tube MOSFET can be controlled to be always in the off state.
In a specific implementation, the second comparing unit 17 may be a comparator. Or the second comparing unit 17 may be other circuit devices or circuit structures capable of realizing the comparing function.
In the embodiment of the present invention, the short circuit detection unit may output a short circuit signal to the control unit 12 when detecting that the output voltage V OUT of the high-side switch circuit 10 is less than a preset short circuit voltage threshold. After receiving the short circuit signal, the control unit 12 may enter a lock (latch) state.
When the control unit 12 is in the locked state, the control unit 12 may control the power transistor MOSFET to be always in the off state. Since the power tube MOSFET is continuously turned off, the short circuit of the high side switching circuit 10 does not affect the reliability of the power tube MOSFET.
In practical applications, the high-side switch circuit 10 may short-circuit in a short time without continuously shorting. In this scenario, if the control unit 12 enters the locked state, the power transistor MOSFET is always in the off state, i.e. the high-side switch circuit 10 may not work normally for a long time.
In order to reduce the influence of short-circuiting on the high-side switch circuit 10, in the embodiment of the present invention, the control unit 12 may output the second control signal to the power tube MOSFET after receiving the short-circuiting signal. The second control signal may be a low level signal to control the power tube MOSFET to turn off. The power tube MOSFET is disconnected after receiving the second control signal. After waiting for the second period of time, the control unit 12 may generate and output a third control signal to the power tube MOSFET, where the third control signal may be a high level signal to control the power tube MOSFET to be turned on. After receiving the third control signal, the power tube MOSFET is switched from the off state to the on state. The short detection unit may re-detect whether the high-side switch circuit 10 is shorted (i.e., re-detect whether the output voltage V OUT is less than the short-circuit voltage threshold V OUT(SC)) after the power transistor MOSFET is re-turned on for a third period of time. If the short circuit detection unit detects that the output voltage V OUT is still smaller than the short circuit voltage threshold V OUT(SC), the short circuit signal is re-output to the control unit 12. The control unit 12 receives the short-circuit signal after outputting the third control signal for N consecutive times, and enters a locking state; n is an integer and N is more than or equal to 2.
That is, the control unit 12 controls the power transistor MOSFET to be turned off after receiving the short-circuit signal, so as to avoid the influence of the short-circuit on the high-side switch circuit 10 and the load circuit. After waiting a period of time (second period of time), the control unit 12 controls the power tube MOSFET to be turned back on. The short detection unit may detect whether the high-side switch circuit 10 is still short-circuited after the power tube MOSFET is turned back on for a certain period of time (third period of time). If the short-circuit detection unit detects that the high-side switching circuit 10 is still short-circuited, a short-circuit signal is sent again to the control unit 12. If the control unit 12 detects that the short-circuit signal is received after the power tube MOSFET is turned on N times continuously, it can be determined that the high-side switch circuit 10 is continuously short-circuited, and thus, it is determined that the locked state is entered.
If the short circuit detection unit detects that the high-side switch circuit 10 is not shorted again, that is, the output voltage V OUT is greater than the short circuit voltage threshold V OUT(SC), the second comparison result of the high level may be output to the control unit 12. The control unit 12 receives the second comparison result of the high level, and can determine that the high-side switch circuit 10 has no short circuit, and continuously charges the load capacitor C OUT.
In a specific implementation, the value of N may be an empirical value or a preset value. In some embodiments, N has a value of 6. In other embodiments, N has a value of 4.
In this embodiment of the present invention, after the enabling time period of the high-side switch circuit 10 exceeds the fourth time period, if the control unit 12 receives the temperature protection trigger signal, the control unit 12 may continuously control the power tube MOSFET to be in the off state.
As can be seen from the above embodiments, the enable period of the high-side switch circuit 10 may not reach the fourth period after the load capacitor is charged. If during this time the control unit 12 receives a temperature protection trigger signal, the control unit 12 may control the power tube MOSFET to be turned off. The short circuit detection unit detects whether or not there is a short circuit in the high-side switch circuit 10. If the short-circuit detection means detects that there is a short circuit in the high-side switch circuit 10, a short-circuit signal may be output to the control means 12. The control unit 12 receives the short-circuit signal and waits for a period of time (e.g., a second period of time) to control the power tube MOSFET to turn on again. If the high-side switch circuit 10 is not shorted after the power tube MOSFET is turned on again, the control unit 12 may control the power tube MOSFET to be turned on continuously until the enabling duration of the high-side switch circuit 10 reaches the fourth duration.
In the embodiment of the present invention, after the enabling time period of the high-side switch circuit 10 reaches the fourth time period, if the control unit 12 receives the temperature protection trigger signal, the control unit 12 may control the power tube MOSFET to be in the off state, so as to not charge the load capacitor any more. Thus, it is possible to avoid the reliability of the high-side switch circuit 10 from being lowered due to an infinite number of restarts. After the power tube MOSFET has been turned off for a period of time, the control unit 12 may re-control the power tube MOSFET to be turned on.
After the enabling duration of the high-side switch circuit 10 reaches the fourth duration, if the control unit 12 does not receive the temperature protection trigger signal, the control unit 12 may control the power tube MOSFET to be continuously in the on state.
In some embodiments, the high-side switching circuit 10 may be integrated in a circuit board, or the high-side switching circuit 10 may be integrated in an integrated circuit chip, which may also be referred to as a high-side switching chip.
The specific operation of the high-side switch circuit 10 according to the embodiment of the present invention will be described in detail.
Referring to fig. 3, an operational waveform diagram of a high-side switching circuit 10 in accordance with an embodiment of the present invention is shown. The high side switching circuit is in the form of a high side switching chip.
When the enable signal is not input to the enable terminal EN of the high-side switch chip, the high-side switch chip is defined to be in an Off (Off) state.
When the enable signal is input to the enable end EN of the high-side switch chip, the high-side switch chip is enabled and starts to work, and the state of the high-side switch chip is defined as a start (Startup) state.
In Startup states, the power tube MOSFET is turned on, and the maximum value of the current I OUT flowing through the power tube MOSFET is the target current I LIM. The high side switch chip charges the load capacitor with the target current I LIM.
In Startup states, when the output voltage V OUT is less than the first voltage V 1, the target temperature protection threshold is the second temperature protection threshold T SW(L), and when the output voltage V OUT is greater than the first voltage V 1, the target temperature protection threshold is the first temperature protection threshold T SW(H).
In the Startup state, when the output voltage V OUT is smaller than the first voltage V 1, the temperature protection unit 14 outputs a temperature protection trigger signal to the control unit 12 when detecting that the real-time temperature of the power tube MOSFET is greater than the temperature threshold corresponding to the first temperature protection threshold. The control unit 12 receives the temperature protection trigger signal and outputs a second control signal to the power tube MOSFET to control the power tube MOSFET to be turned off. After the power tube MOSFET is turned off, the temperature gradually drops. After the power tube MOSFET is turned off for a preset period of time, the control unit 12 may control the power tube MOSFET to be turned back on. Or the control unit controls the power tube MOSFET to be turned on again when detecting that the temperature protection trigger signal is in a low level (the temperature protection trigger signal can be understood as disappearing). And the method is repeated in a circulating way until the voltage at the two ends of the load capacitor reaches the target voltage.
As shown in fig. 3, the output voltage V OUT does not always increase during the first half of Startup, but gradually increases in a manner of increasing (the real-time temperature of the power tube MOSFET does not trigger the temperature protection) and decreasing (the real-time temperature of the power tube MOSFET triggers the temperature protection) again.
When the enabling duration of the high-side switch chip reaches the first duration T SCDT, the control unit 12 controls the short-circuit detection unit to enable. The short circuit detection unit detects the magnitude relation between the output voltage V OUT and the short circuit voltage threshold V OUT(SC) so as to judge whether the high-side switch chip is short-circuited.
And when the enabling time length of the high-side switch chip reaches a fourth time length T startup, defining that the high-side switch chip enters an Active state. When the high-side switch chip enters the Active state, if the control unit 12 receives the temperature protection trigger signal, the control unit 12 outputs a second control signal to the power tube MOSFET to control the power tube MOSFET to be disconnected. In the Active state, after the power tube MOSFET is disconnected, the high-side switch chip does not control the power tube MOSFET to be conducted any more. Or in the Active state, after the power tube MOSFET is disconnected, the high-side switch chip can also control the power tube MOSFET to be switched on again after a period of time so as to judge whether short circuit occurs again. If the occurrence of short circuit is detected M times continuously, the control unit 12 controls the power tube to be continuously in the off state.
Referring to fig. 4, a schematic waveform diagram of a short circuit of a high-side switch circuit in an embodiment of the present invention is shown.
In fig. 4, after the high-side switch chip enable duration reaches the first duration T SCDT, the control unit 12 controls the short-circuit detection unit to enable. The short circuit detection unit detects the magnitude relation between the output voltage V OUT and the short circuit voltage threshold V OUT(SC), and determines V OUT＜VOUT(SC). Thereby, the control unit 12 enters a locked state.
Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention, and the scope of the invention should be assessed accordingly to that of the appended claims.

Claims (7)

1. A high-side switching circuit, comprising: the device comprises a target current generating unit, a first comparing unit, a power tube, a control unit, a protection threshold generating unit and a temperature protection unit, wherein:
the target current generating unit generates and outputs a target current;
The first input end of the first comparison unit inputs the output voltage of the high-side switch circuit, the second input end of the first comparison unit inputs the first voltage, and the output end of the first comparison unit outputs a first comparison result; the first voltage is the difference between the input voltage of the high-side switch circuit and the voltage drop at two ends of a first voltage source; the output voltage of the high-side switch circuit is the voltage at two ends of the load capacitor;
the control unit outputs a first control signal to the protection threshold generating unit based on the first comparison result; and controlling the power tube to be disconnected when the temperature protection trigger signal is received, and controlling the power tube to be connected when the temperature protection trigger signal is not received; and controlling the working current of the power tube when the power tube is conducted to be equal to the target current;
The protection threshold generating unit outputs a target temperature protection threshold based on the first control signal; the target temperature protection threshold is a first temperature protection threshold or a second temperature protection threshold, and the first temperature protection threshold is larger than the second temperature protection threshold; when the output voltage is greater than the first voltage, the target temperature protection threshold is the first temperature protection threshold; when the output voltage is smaller than the first voltage, the target temperature protection threshold is the second temperature protection threshold;
And the temperature protection unit responds to the fact that the real-time temperature of the power tube is larger than the target temperature protection threshold value, and outputs the temperature protection trigger signal.
2. The high-side switching circuit of claim 1, further comprising: the short circuit detection unit is used for outputting a short circuit signal to the control unit when detecting that the output voltage is smaller than a preset short circuit voltage threshold value;
The control unit is also used for entering a locking state after receiving the short circuit signal; and when the control unit is in the locking state, the power tube is controlled to be disconnected.
3. The high-side switching circuit according to claim 2, wherein the short-circuit detection unit includes: a second comparing unit and a short-circuit voltage threshold generating unit, wherein:
The first input end of the second comparison unit is coupled with the output end of the high-side switch circuit, and the output end of the second comparison unit is coupled with the control unit;
and the short circuit voltage threshold generating unit is used for generating the short circuit voltage threshold and outputting the short circuit voltage threshold to the second input end of the second comparing unit.
4. A high-side switching circuit according to claim 2 or 3, wherein the control unit outputs an enable signal to the short-circuit detection unit to trigger the short-circuit detection unit to enable after the enable time period reaches the first time period; and closing the short circuit detection unit after the enabling time length reaches a fourth time length; and before the enabling time reaches the fourth time, a load capacitor coupled with the high-side switch circuit is charged.
5. The high side switching circuit according to claim 4, wherein the control unit further controls the power tube to be continuously turned off if the temperature protection trigger signal is received after the enabling time period reaches the fourth time period.
6. The high side switching circuit according to claim 4, wherein the control unit controls the power tube to be turned off if the short circuit signal is received before the enabling time period reaches the fourth time period, and controls the power tube to be turned back on after waiting for a second time period; and after the power tube is continuously conducted for N times, the short circuit signals are received, and the power tube enters the locking state; n is an integer and N is more than or equal to 2;
and the short circuit detection unit is used for detecting whether the output voltage is smaller than the short circuit voltage threshold value again after the power tube is turned on again for a third time period, and outputting the short circuit signal to the control unit again when the output voltage is smaller than the short circuit voltage threshold value.
7. The high-side switching circuit according to claim 1, wherein the protection threshold generating unit includes: a first protection threshold generating unit, a second protection threshold generating unit, and a switching unit, wherein:
the first protection threshold generating unit generates the first temperature protection threshold;
The second protection threshold generating unit generates the second temperature protection threshold;
the switching unit outputs the first temperature protection threshold value based on the first control signal; or outputting the second temperature protection threshold.
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