Current detection circuit and electronic chip

Abstract

According to the current detection circuit of the power tube and the electronic chip, the first end of the power tube is used for being connected with a battery, the second end of the power tube is used for providing output voltage for a load, and the current detection circuit comprises a reference voltage generation module and a short circuit state determination module; the reference voltage generation module comprises a resistor unit and a first transistor connected with a gate and a drain, one end of the resistor unit is connected with the first end of the power tube, and the other end of the resistor unit is connected with the gate end and the drain end of the first transistor so as to generate reference voltage with a negative temperature coefficient; and the short-circuit state determination module is configured to compare the reference voltage with the voltage on the second end of the power tube to generate a short-circuit state signal, so that the deviation of current detection caused by the temperature influence in the charging chip is reduced, and the accuracy of determining whether a short-circuit fault occurs in the battery circuit is ensured.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to the technical field of integrated circuits and related technical fields, and in particular, to a current detection circuit and an electronic chip. Background Art

[0002] In charging chips, in order to ensure the safe operation of the chip, many protection functions need to be included. Output short-circuit protection is one of them. Short-circuit detection is usually performed by detecting the current signal flowing through the power tube. The current signal flowing through the power tube will be reflected in the voltage difference at both ends of the power tube through the on-resistance of the power tube.

[0003] However, since the on-resistance of the power tube has a temperature coefficient, it will change with temperature, and the constant voltage threshold detection will affect the accuracy of short-circuit detection. Therefore, reducing the deviation caused by temperature influence on current detection has always been one of the difficulties in the design of charging chip circuits. Summary of the invention

[0004] The embodiments described herein provide a current detection circuit and an electronic chip that can reduce the deviation of current detection caused by temperature effects in charging chips.

[0005] In a first aspect, according to the present disclosure, a current detection circuit of a power tube is provided, wherein a first end of the power tube is used to connect a battery, a second end of the power tube is used to provide an output voltage to a load, and the current detection circuit includes a reference voltage generation module and a short circuit state determination module;

[0006] The reference voltage generating module comprises a resistance unit and a first transistor connected to a gate and a drain, one end of the resistance unit is connected to the first end of the power tube, and the other end of the resistance unit is connected to the gate and the drain of the first transistor, so as to generate a reference voltage with a negative temperature coefficient;

[0007] The short-circuit state determination module is configured to compare the reference voltage with the voltage on the second end of the power tube to generate a short-circuit state signal.

[0008] In some embodiments of the present disclosure, the first transistor operates in a subthreshold region.

[0009] In some embodiments of the present disclosure, the resistance unit includes a first resistor and a second resistor, the first end of the first resistor is electrically connected to the first end of the power tube, the second end of the first resistor is electrically connected to the first end of the second resistor, the second end of the second resistor is electrically connected to the gate and drain ends of the first transistor, and the reference voltage is provided at the connection point between the first resistor and the second resistor.

[0010] In some embodiments of the present disclosure, the power tube is a PMOS tube, and the first transistor is an NMOS tube.

[0011] In some embodiments of the present disclosure, the short-circuit state determination module includes a comparator, a positive input terminal of the comparator is connected to the reference voltage, and a negative input terminal of the comparator is connected to the voltage on the second end of the power tube.

[0012] In some embodiments of the present disclosure, a current mirror module is also included;

[0013] The current mirror module is configured to provide a bias current for the comparator according to the current on the first transistor.

[0014] In some embodiments of the present disclosure, the current mirror module includes a second transistor, a gate terminal of the second transistor is electrically connected to a gate terminal of the first transistor;

[0015] The first power supply terminal of the comparator is connected to the first end of the power tube, and the second power supply terminal of the comparator is grounded through the second transistor.

[0016] In some embodiments of the present disclosure,

[0017] in,

[0018] The threshold voltage of the first transistor satisfies:

[0019] V thn =V th0 -cT

[0020] Among them, V th0 is the threshold voltage of the first transistor when the temperature is T=0;

[0021] The on-resistance of the power tube satisfies: Among them, R0 is the on-resistance of the power tube when T=0;

[0022] The resistance of the first resistor is R1, the resistance of the second resistor is R2, V BAT is the battery voltage of the battery.

[0023] In a second aspect, according to the content of the present disclosure, an electronic chip is provided, comprising the current detection circuit described in any one of the first aspects and a first power tube, wherein the current detection circuit is used to detect the first power tube.

[0024] In some embodiments of the present disclosure, the electronic chip further includes a control module and a second power tube.

[0025] One end of the second power tube is connected to the power supply end, and the other end of the second power tube is connected to the second end of the first power tube;

[0026] The control module is used to output control signals to the first power tube and the second power tube to achieve charge and discharge control.

[0027] The disclosed embodiments provide a current detection circuit and an electronic chip for a power tube. The current detection circuit includes a reference voltage generation module, and the reference voltage is negatively correlated with the temperature coefficient. When the on-resistance of the power tube increases with temperature, the on-voltage drop increases, causing the voltage at the second end of the power tube to decrease with increasing temperature. Since the reference voltage has a negative temperature coefficient, the reference voltage decreases with increasing temperature. By setting the parameters of each electronic device included in the reference voltage generation module, the slope of the reference voltage is adjusted, thereby ensuring that the change in the reference voltage with temperature is offset by the change in the voltage at the second end of the power tube, so that the determined short-circuit current threshold is independent of the temperature coefficient, thereby ensuring the accuracy of determining whether a short-circuit fault occurs in the battery circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly described below. It should be noted that the drawings described below only relate to some embodiments of the present disclosure, but are not intended to limit the present disclosure, wherein:

[0029] Figure 1 is a structural schematic diagram of a current detection circuit provided by an embodiment of the present disclosure;

[0030] Figure 2 It is a schematic diagram of the structure of an electronic chip provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative work also fall within the scope of protection of the present disclosure.

[0032] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by a person skilled in the art to which the subject matter of the present disclosure belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the specification and the relevant art, and will not be interpreted in an idealized or overly formal form unless otherwise explicitly defined herein. As used herein, a statement that two or more parts are "connected" or "coupled" together shall mean that the parts are joined together directly or through one or more intermediate components.

[0033] In all embodiments of the present disclosure, terms such as “first” and “second” are used only to distinguish one component (or a part of a component) from another component (or another part of a component).

[0034] Unless the context clearly indicates otherwise, the singular form of the words used herein and in the appended claims includes the plural and vice versa. Thus, when referring to the singular, the plural form of the corresponding term is generally included. Similarly, the words "comprise" and "include" are to be interpreted as inclusive rather than exclusive. Likewise, the terms "include" and "or" should be interpreted as inclusive unless such interpretation is expressly prohibited herein. Where the term "example" is used herein, particularly when it is located after a group of terms, the "example" is merely exemplary and illustrative and should not be considered exclusive or comprehensive.

[0035] Based on the problems existing in the prior art, the present disclosure provides a current detection circuit for a power tube. Figure 1 is a schematic diagram of a current detection circuit of a power tube provided by an embodiment of the present disclosure, such as Figure 2 As shown, the current detection circuit of the power tube, the first end of the power tube MP0 is used to connect to the battery, and the second end of the power tube MP0 is used to provide an output voltage to the load, including: a reference voltage generation module 30 and a short circuit state determination module 40; the reference voltage generation module 30 includes a resistor unit 31 and a first transistor MN1 connected to the gate and drain, one end of the resistor unit 31 is connected to the first end of the power tube MP0, and the other end of the resistor unit 31 is connected to the gate and drain of the first transistor MN1, so as to generate a reference voltage V having a negative temperature coefficient REF Short circuit state determination module 40, is configured to reference voltage V REF The voltage is compared with the voltage at the second end of the power transistor MP0 to generate a short-circuit state signal.

[0036] In the prior art, since the on-resistance of the power tube is positively correlated with the temperature coefficient, the voltage at the second end of the power tube is negatively correlated with the temperature coefficient. Therefore, the short-circuit current threshold determined based on a fixed reference voltage and the voltage at the second end of the power tube is related to the temperature coefficient, and there is a problem that the short-circuit current threshold of the charging chip is too small when the junction temperature rises.

[0037] Based on the problems existing in the prior art, in the embodiment of the present disclosure, by setting a reference voltage generation module and a short-circuit state determination module, the reference voltage generation module outputs a reference voltage to the short-circuit state determination module, and the reference voltage output by the reference voltage generation module is negatively correlated with the temperature coefficient. At this time, the short-circuit state determination module compares the reference voltage with the voltage on the second end of the power tube to generate short-circuit state information. Since the reference voltage output by the reference voltage generation module is negatively correlated with the temperature coefficient, the short-circuit current threshold determined according to the reference voltage has a zero temperature coefficient, thereby ensuring the accuracy of the short-circuit state information determined by the short-circuit current threshold with a zero temperature coefficient, and avoiding the problem that the short-circuit current threshold of the charging chip is too small when the junction temperature rises.

[0038] Specifically, if the reference voltage is V REF , the battery voltage is V BAT , the on-resistance of the power tube satisfies Then the short-circuit current threshold satisfies: Among them, V BAT is the battery voltage, I SC is the short-circuit current threshold, is the on-resistance of the power tube, is the width-to-length ratio of the power tube channel, V gs is the gate-source voltage of the power tube, V th is the threshold voltage of the power tube. From the above formula, it can be seen that the on-resistance of the power tube has a positive temperature coefficient. If the high-order temperature coefficient of the on-resistance of the power tube is ignored and only the first-order temperature coefficient of the on-resistance of the power tube is considered, the on-resistance of the power tube can be recorded as: Among them, R0 is the on-resistance of the power tube when T=0.

[0039] Since the on-resistance of the power tube has a positive temperature coefficient and the reference voltage has a negative temperature coefficient, by configuring the parameters of the electronic components that generate the reference voltage, the relationship between the on-resistance of the power tube and the temperature coefficient can be made opposite to the relationship between the reference voltage and the temperature coefficient. At this time, based on the formula It can be determined that the short-circuit current threshold is independent of the temperature coefficient, thus avoiding the problem of the short-circuit current threshold being too small when the junction temperature of the charging chip rises.

[0040] In addition, if the current signal provided by the battery to the output load through the power tube is I A, then the output voltage of the output node satisfies: The reference voltage satisfies: By comparing the relationship between the output voltage and the reference voltage, it can be determined that the current signal provided by the battery to the output load through the power tube is I A and the short-circuit current threshold I SC The relationship between the battery circuit and the load can be used to determine whether the battery circuit is faulty.

[0041] The disclosed embodiment provides a current detection circuit for a power tube. The current detection circuit includes a reference voltage generation module. The reference voltage is negatively correlated with the temperature coefficient. When the on-resistance of the power tube increases with temperature, the on-voltage drop increases, causing the voltage at the second end of the power tube to decrease with increasing temperature. Since the reference voltage has a negative temperature coefficient, the reference voltage decreases with increasing temperature. By setting the parameters of each electronic device included in the reference voltage generation module, the slope of the reference voltage is adjusted, thereby ensuring that the change in the reference voltage with temperature is offset by the change in the voltage at the second end of the power tube, so that the determined short-circuit current threshold is independent of the temperature coefficient, thereby ensuring the accuracy of determining whether a short-circuit fault occurs in the battery circuit.

[0042] In a specific embodiment, continue to combine Figure 2 The resistor unit includes a first resistor R1 and a second resistor R2. The first end of the first resistor R1 is electrically connected to the first end of the power tube, the second end of the first resistor R1 is electrically connected to the first end of the second resistor R2, the second end of the second resistor R2 is electrically connected to the gate end of the first transistor MN1 and the drain end of the first transistor MN1, and a reference voltage V is provided at the connection point between the first resistor R1 and the second resistor R2. REF , a second end of the first transistor MN1 is electrically connected to a second end of the battery.

[0043] The first transistor MN1 is an NMOS transistor, and the first transistor MN1 operates in a subthreshold region.

[0044] In a specific implementation, a reference current is determined according to the battery voltage, the first resistor R1, the second resistor R2 and the threshold voltage of the first transistor MN1, and a reference voltage is determined according to the reference current and the first resistor, and the reference current is positively correlated with the temperature coefficient.

[0045] Specifically, the resistance of the first resistor is R1, the resistance of the second resistor is R2, and the gate-source voltage of the first transistor is V gs1 , at this time, the reference current satisfies: The reference voltage meets the following requirements: Since the reference current is the same as the on-current of the first transistor, the reference current also satisfies: in, Vgs1 is the gate-source voltage of the first transistor at temperature T, V thn is the threshold voltage of the first transistor at temperature T, so In order to reduce the static power consumption of the battery, the first transistor is designed to operate in the subthreshold region to obtain a smaller reference current I B , then V gs1 ≈V thn , so there is

[0046] I B (R1+R2)+V thn =V BAT

[0047] The reference current also satisfies:

[0048]

[0049] Since the threshold voltage of the first transistor satisfies:

[0050] V thn =V th0 -cT

[0051] Among them, V th0 is the threshold voltage of the first transistor when the temperature is T=0.

[0052] The threshold voltage of the first transistor exhibits a negative temperature coefficient, and the reference current I B It exhibits a positive temperature coefficient, that is, the reference current is positively correlated with the temperature coefficient.

[0053] Therefore, the reference current also satisfies:

[0054]

[0055] At this time, the determined reference voltage satisfies:

[0056]

[0057] In the embodiment of the present disclosure, a short-circuit state determination module is also included. The short-circuit state determination module determines the relationship between the current signal provided by the battery to the output load through the power tube and the short-circuit current threshold according to the output voltage and the reference voltage of the output node.

[0058] Specifically, another V REF =V OUT , then it satisfies:

[0059]

[0060] That is:

[0061]

[0062] in,

[0063] By converting the above formula we get:

[0064]

[0065] When another hour, The determined short-circuit current threshold has a zero temperature coefficient and does not change with changes in temperature.

[0066] By setting the reference voltage generation module to include a first resistor, a second resistor and a first transistor, the first transistor is an NMOS tube, and the first transistor works in a subthreshold region, at this time, the reference voltage output by the reference voltage generation module satisfies:

[0067]

[0068] in,

[0069] By setting the reference voltage to be negatively correlated with the temperature coefficient, the change in the reference voltage with temperature is related to the resistance values ​​of the first resistor and the second resistor. By setting the resistance values ​​of the first resistor and the second resistor, it can be ensured that the change in the reference voltage with temperature and the change in the on-state voltage drop of the power tube with temperature are offset, thereby ensuring that the short-circuit current threshold has a zero temperature coefficient and will not change with changes in temperature.

[0070] In a specific implementation manner, see Figure 2 The short-circuit state determination module includes a comparator, a positive input terminal of the comparator receives a reference voltage, a reverse input terminal of the comparator receives a voltage on the second end of the power tube, a first power supply terminal of the comparator is electrically connected to the first end of the battery, and a second power supply terminal of the comparator is electrically connected to the second end of the battery.

[0071] By setting the short-circuit state determination module to include a comparator, the reference voltage and the output voltage are compared based on the comparator to determine whether a short-circuit fault occurs in the battery circuit.

[0072] In a specific implementation manner, see Figure 2 , the current detection circuit also includes a current mirror module;

[0073] The current mirror module is configured to provide a bias current for the comparator according to the current on the first transistor. Specifically, the current mirror module includes a second transistor, and the gate terminal of the second transistor is electrically connected to the gate terminal of the first transistor.

[0074] The second transistor is an NMOS transistor.

[0075] In the embodiment of the present disclosure, a current mirror module is provided, which mirrors the reference current determined by the output voltage determination module once to provide a bias current for the comparator, thereby eliminating the reference current generation module and further reducing the static power consumption of the battery.

[0076] The current detection circuit provided by the embodiment of the present invention can detect the current at the input node (V IN ) When there is no power supply, it can also realize the short-circuit protection function of the battery and reduce the deviation of current detection caused by temperature.

[0077] The embodiment of the present disclosure also provides an electronic chip, combining Figure 1 and Figure 2 The electronic chip includes the current detection circuit described in any one of the above embodiments and the first power tube MP0, and the current detection circuit is used to detect the first power tube MP0.

[0078] The electronic chip also includes a control module and a second power tube MN0, one end of the second power tube MN0 is connected to the power supply end, and the other end of the second power tube MN0 is connected to the second end of the first power tube MP0; the control module 10 is used to output control signals to the first power tube MP0 and the second power tube MN0 to realize charging and discharging control.

[0079] In a specific embodiment, in combination with Figure 2 When the working current of the output load is less than or equal to the maximum conduction current of the second power tube MN0, the input node V IN A current signal is provided to the output load. At this time, the maximum conduction current flowing through the second power tube MN0 flows to the load circuit to provide a current signal to the load, and flows to the battery through the first power tube MP0 to charge the battery. The current signal flowing to the battery satisfies the maximum conduction current of the second power tube MN0 minus the working current of the output load, and the battery is in a charging state. When the working current of the output load is greater than the maximum conduction current of the second power tube MN0, at this time, the current signal flowing through the second power tube MN0 can no longer meet the working current of the output load. At this time, a current signal is provided to the output load through the battery. The current signal provided by the battery to the output load satisfies the working current of the output load minus the maximum conduction current of the second power tube MN0, and the battery is in a discharging state. When the battery is in a discharging state, in order to ensure the working safety of the battery, it is necessary to ensure that the current signal output by the battery is less than the short-circuit current threshold to avoid a short-circuit fault in the battery circuit. In addition, when a current signal is provided to the output load through the battery, the output voltage of the output node is obtained, and then the output voltage of the output node is compared with the reference voltage to determine whether a short-circuit fault occurs in the battery circuit.

[0080] The embodiments of the present disclosure also provide an electronic device. The electronic device includes an electronic chip according to the embodiments of the present disclosure. The electronic device is, for example, a smart terminal device, such as a tablet computer, a smart phone, etc.

[0081] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0082] It should be understood that "one embodiment" or "an embodiment" mentioned throughout the specification means that specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present application. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It should be understood that in various embodiments of the present application, the size of the serial number of each step / process mentioned above does not mean the order of execution, and the execution order of each step / process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present application. In addition, the serial numbers of the embodiments of the present application mentioned above are only for description and do not represent the advantages and disadvantages of the embodiments.

[0083] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0084] The above description is only a preferred embodiment of the present disclosure and is not intended to limit the present disclosure. For those skilled in the art, the present disclosure may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A current detection circuit for a power tube, wherein the first end of the power tube is used to connect to a battery, and the second end of the power tube is used to provide an output voltage to a load, characterized in that: The current detection circuit includes a reference voltage generation module and a short circuit state determination module; The reference voltage generating module comprises a resistance unit and a first transistor connected to a gate and a drain, one end of the resistance unit is connected to the first end of the power tube, and the other end of the resistance unit is connected to the gate and the drain of the first transistor, so as to generate a reference voltage with a negative temperature coefficient; The short-circuit state determination module is configured to compare the reference voltage with the voltage on the second end of the power tube to generate a short-circuit state signal.

2. The circuit according to claim 1, characterized in that The first transistor operates in a subthreshold region.

3. The circuit according to claim 1, characterized in that The resistance unit includes a first resistor and a second resistor, wherein the first end of the first resistor is electrically connected to the first end of the power tube, the second end of the first resistor is electrically connected to the first end of the second resistor, the second end of the second resistor is electrically connected to the gate and drain ends of the first transistor, and the reference voltage is provided at the connection point between the first resistor and the second resistor.

4. The circuit according to claim 1, characterized in that The power tube is a PMOS tube, and the first transistor is an NMOS tube.

5. The circuit according to claim 1, characterized in that The short-circuit state determination module includes a comparator, a positive input terminal of the comparator is connected to the reference voltage, and a negative input terminal of the comparator is connected to the voltage on the second end of the power tube.

6. The circuit according to claim 5, characterized in that Also included is a current mirror module; The current mirror module is configured to provide a bias current for the comparator according to the current on the first transistor.

7. The circuit according to claim 6, characterized in that The current mirror module includes a second transistor, a gate terminal of the second transistor is electrically connected to a gate terminal of the first transistor; The first power supply terminal of the comparator is connected to the first end of the power tube, and the second power supply terminal of the comparator is grounded through the second transistor.

8. The circuit according to claim 3, characterized in that in, The threshold voltage of the first transistor satisfies: V thn =V th0 -cT Among them, V th0 is the threshold voltage of the first transistor when the temperature is T=0; The on-resistance of the power tube satisfies: R dson =aT+R0, where R0 is the on-resistance of the power tube when T=0; The resistance of the first resistor is R1, the resistance of the second resistor is R2, V BAT is the battery voltage of the battery.

9. An electronic chip, characterized in that: It comprises the current detection circuit as described in any one of claims 1 to 8 and a first power tube, wherein the current detection circuit is used to detect the first power tube.

10. The electronic chip according to claim 9, characterized in that: The electronic chip also includes a control module and a second power tube. One end of the second power tube is connected to the power supply end, and the other end of the second power tube is connected to the second end of the first power tube; The control module is used to output control signals to the first power tube and the second power tube to achieve charge and discharge control.

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