Charge pump overcurrent detection circuit and optical sensing system

Abstract

The invention provides a charge pump overcurrent detection circuit and an optical sensing system. The charge pump overcurrent detection circuit comprises a charge pump, a detection module and a control module, the detection module is used for detecting the input power supply current of the charge pump and outputting an overcurrent indication signal; the control module is used for receiving the overcurrent indication signal and outputting an adjusting signal; and the charge pump is used for reducing the output voltage of the charge pump from the initial working voltage to the target working voltage in response to the adjusting signal. According to the invention, the problem of normal working voltage drop caused by a traditional output end sampling resistor is fundamentally avoided, and the efficiency and the reliability are remarkably improved; and meanwhile, quick response and accurate control on an overcurrent state are realized, the output voltage can be actively adjusted to a safe range, and intelligent protection is provided for the charge pump and a load thereof.

Description

Technical Field

[0001] This application relates to the field of integrated circuit technology, and more specifically, to a charge pump overcurrent detection circuit and an optical sensing system. Background Technology

[0002] Charge pumps, as highly efficient DC-DC voltage conversion circuits, are widely used to provide bias for various devices requiring high operating voltages. For example, in the field of photoelectric detection, single-photon avalanche diode (SPAD) arrays require charge pumps to provide a bias voltage (i.e., overvoltage) higher than their breakdown voltage (BV) to operate in Geiger mode. In practical applications, if the current exceeds the charge pump's maximum driving capacity for an extended period, it is highly likely that the charge pump and SPAD array will be permanently burned out due to overheating. Therefore, effective overcurrent detection and protection of charge pumps are crucial.

[0003] Currently, conventional overcurrent protection schemes for charge pumps mainly involve connecting a sampling resistor in series between the output of the charge pump and the load (SPAD array). When the output current is too high, the voltage drop across this sampling resistor increases significantly, thereby reducing the actual voltage across the load and achieving current limiting protection. However, this scheme increases design complexity, leading to additional power consumption and chip area overhead. Moreover, this method cannot achieve precise digital control. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a charge pump overcurrent detection circuit and an optical sensing system to overcome the problems in the prior art.

[0005] In a first aspect, embodiments of this application provide a charge pump overcurrent detection circuit, including a charge pump, a detection module, and a control module; The detection module is used to detect the input power current of the charge pump and output an overcurrent indication signal; The control module is used to receive the overcurrent indication signal and output an adjustment signal; The charge pump is used to reduce its output voltage from the initial operating voltage to the target operating voltage in response to the adjustment signal; The aforementioned detection module includes: A current detection unit is used to convert the input power supply current into a detection voltage; The comparison unit is used to compare the detected voltage with the reference voltage and generate the overcurrent indication signal.

[0006] In some technical solutions of this application, the above-mentioned detection module further includes: A filtering unit is connected between the current detection unit and the comparison unit, and is used to filter the detected voltage.

[0007] In some technical solutions of this application, the current detection unit includes a high-speed current detection amplifier; the comparison unit includes a high-speed comparator.

[0008] In some technical solutions of this application, the above-mentioned filtering unit includes an RC filter, and the filtering bandwidth is adjustable.

[0009] In some technical solutions of this application, the above-mentioned detection module further includes: a generation module; The generation module is used to generate a reference voltage with an adjustable voltage value.

[0010] In some technical solutions of this application, the above-mentioned generation module includes: The core circuit of the bandgap reference is used to generate a reference voltage; A level shifter or voltage divider network is connected to the output of the bandgap reference core circuit to make the value of the reference voltage adjustable.

[0011] In some technical solutions of this application, the above-mentioned generation module includes: a digital-to-analog converter, used to receive digital configuration signals and directly output the reference voltage.

[0012] In some technical solutions of this application, the control module includes digital logic circuitry for generating the adjustment signal in digital form based on the overcurrent indication signal.

[0013] Secondly, embodiments of this application provide an optical sensing system, including: a single-photon avalanche diode array; a quenching circuit connected to the single-photon avalanche diode array; and the aforementioned charge pump overcurrent detection circuit, used to provide a bias voltage to the single-photon avalanche diode array and realize overcurrent protection.

[0014] The technical solutions provided by the embodiments of this application may include the following beneficial effects: This application discloses a charge pump overcurrent detection circuit, including a charge pump, a detection module, and a control module. The detection module is used to detect the input power supply current of the charge pump and output an overcurrent indication signal. The control module is used to receive the overcurrent indication signal and output an adjustment signal. The charge pump is used to respond to the adjustment signal by reducing its output voltage from an initial operating voltage to a target operating voltage.

[0015] This application fundamentally avoids the normal operating voltage drop problem caused by the traditional output sampling resistor, significantly improving efficiency and reliability. At the same time, it achieves rapid response and precise control to overcurrent conditions, and can actively adjust the output voltage to a safe range, providing intelligent protection for the charge pump and its load.

[0016] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of a charge pump overcurrent detection circuit provided in an embodiment of this application is shown; Figure 2 A schematic diagram of an optical sensing system provided in an embodiment of this application is shown. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the accompanying drawings in this application are for illustrative and descriptive purposes only and are not intended to limit the scope of protection of this application. Furthermore, it should be understood that the schematic drawings are not drawn to scale. The flowcharts used in this application illustrate operations implemented according to some embodiments of this application. It should be understood that the operations in the flowcharts may not be implemented in sequence, and steps without logical contextual relationships may be reversed or implemented simultaneously. In addition, those skilled in the art, guided by the content of this application, may add one or more other operations to the flowcharts, or remove one or more operations from the flowcharts.

[0020] Furthermore, the described embodiments are merely some, not all, of the embodiments of this application. The components of the embodiments of this application described and illustrated herein can typically be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0021] It should be noted that the term "comprising" will be used in the embodiments of this application to indicate the presence of the features declared thereafter, but does not exclude the addition of other features.

[0022] Charge pumps, as highly efficient DC-DC voltage conversion circuits, are widely used to provide bias for various devices that require high operating voltages. For example, in the field of photodetection, single-photon avalanche diode (SPAD) arrays require charge pumps to provide a bias voltage (i.e., overvoltage) higher than their breakdown voltage (BV) to operate in Geiger mode.

[0023] However, in practical applications, the load current of the SPAD array fluctuates drastically with changes in incident light intensity. When exposed to strong light, a large number of SPADs may simultaneously undergo avalanche breakdown, causing a sharp increase in the charge pump's load current. If this current exceeds the charge pump's maximum driving capacity for an extended period, it is highly likely that the charge pump and SPAD array will be permanently burned out due to overheating. Therefore, effective overcurrent detection and protection of the charge pump are crucial.

[0024] Currently, conventional overcurrent protection schemes for charge pumps mainly involve connecting a sampling resistor in series between the output of the charge pump and the load (SPAD array). When the output current is too large, the voltage drop across this sampling resistor will increase significantly, thereby reducing the actual voltage across the load and achieving the purpose of current limiting protection.

[0025] However, this existing technical solution has two obvious drawbacks: First, a continuous voltage drop will occur across the sampling resistor during normal system operation. To compensate for this voltage drop and ensure that the load receives sufficient operating voltage, the charge pump must increase its output voltage accordingly. This not only increases the design complexity of the charge pump itself but also leads to additional power consumption and chip area overhead.

[0026] Second, this method cannot achieve precise digital control. Its protection mechanism is analog and passive, making it difficult to interact with digital processing systems. Therefore, it cannot accurately and flexibly adjust the output voltage of the charge pump in real time according to complex system states (such as different operating modes, temperature compensation, etc.).

[0027] Based on this, embodiments of this application provide a charge pump overcurrent detection circuit and an optical sensing system. Some implementation methods of this application are described in detail below. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0028] Figure 1 A schematic diagram of a charge pump overcurrent detection circuit according to an embodiment of this application is shown, including a charge pump, a detection module, and a control module. The detection module detects the input power supply current of the charge pump in real time. When the input power supply current is normal, the overcurrent indication signal (such as Vflag) output by the detection module is low. When the system is overloaded, causing the input power supply current to increase and exceed a set threshold, the detection module outputs a high-level overcurrent indication signal.

[0029] The control module (such as a digital state machine or microcontroller) continuously monitors the overcurrent indication signal. Once the signal goes high, the control module immediately outputs a regulation signal (Vctrl) to the charge pump. This regulation signal is a digital command that instructs the charge pump to reduce its output voltage.

[0030] Charge pumps typically incorporate a voltage regulation mechanism (e.g., by altering the internal switching timing or the voltage division ratio of the feedback network). In response to this regulation signal, it rapidly reduces its output voltage from an initial operating voltage (e.g., SPAD breakdown voltage + overvoltage) to a safe target operating voltage (e.g., below the SPAD breakdown voltage). This reduction in output voltage directly decreases the current flowing through the load (e.g., the SPAD), thus protecting both the charge pump and the load from damage caused by excessive current.

[0031] In an alternative implementation, see [reference] Figure 2 In this embodiment, the detection module includes: A current detection unit is used to convert the input power supply current into a detection voltage; The comparison unit is used to compare the detected voltage with the reference voltage and generate the overcurrent indication signal.

[0032] The detection module further includes a filtering unit connected between the current detection unit and the comparison unit, used to filter the detection voltage.

[0033] The current sensing unit employs a high-speed current sensing amplifier (Cs). It senses the current through a sampling resistor (Rsense) connected in series in the input power path and converts it into a proportional sensing voltage (Vsample).

[0034] The filtering unit is an RC low-pass filter connected to the output of the current sense amplifier. It filters out high-frequency noise in the current sampling signal, providing a smooth sense voltage to subsequent circuits. By adjusting the values ​​of R and C using analog trimming or other techniques, the filter bandwidth can be precisely set to balance response speed and noise immunity.

[0035] The comparator unit employs a high-speed, high-gain comparator (Comp). Its non-inverting input receives the filtered detection voltage, and its negative input receives a precise reference voltage (Vref). When Vsample > Vref, the comparator output flips to a high level, serving as an overcurrent indication signal (Vflag).

[0036] The detection module further includes: a generation module; The generation module is used to generate a reference voltage with an adjustable voltage value.

[0037] The generation module is used to generate an adjustable Vref. In this embodiment, it consists of a bandgap reference core circuit and a voltage divider network. The bandgap reference generates a stable 1.2V reference, and the voltage divider network (which may consist of a series of resistors and analog switches) generates the desired Vref value based on this reference, which can be configured via a digital signal. Alternatively, the generation module can be a digital-to-analog converter, with a user-configurable digital configuration signal. The analog converter receives the digital configuration signal and directly outputs the reference voltage.

[0038] In operation, the current-sensing amplifier Cs continuously monitors the input power supply VDD current. Its output voltage is smoothed by an RC filter and then compared with the adjustable Vref at the non-inverting and inverting inputs of the high-speed comparator Comp. If the system experiences an overcurrent, Vsample > Vref, the comparator output Vflag is pulled high to a digital value. The digital output Vctrl adjusts the charge pump output voltage below SPAD BV, thereby shutting down SPAD and protecting system components from burnout. If the system is operating normally, Vflag remains low, and the digital output does not perform any operation.

[0039] This application eliminates the need for a series sampling resistor between the charge pump and the load by detecting the input power supply current instead of the output current, thereby eliminating the additional voltage drop during normal operation, ensuring system efficiency, and simplifying the charge pump design. It employs a high-speed current sensing amplifier and a high-speed comparator, combined with an adjustable bandwidth filter unit, to achieve fast response and high-precision overcurrent detection. Both the reference voltage and the filter bandwidth are adjustable, allowing for flexible configuration of the overcurrent detection threshold according to the application scenario and optimizing the balance between response speed and noise immunity. A digital control module enables precise and flexible adjustment of the charge pump output voltage, facilitating integration into more complex system state management. Finally, when providing bias voltage for applications such as single-photon avalanche diode (SPAD) optical sensing systems, this circuit effectively prevents overcurrent damage under conditions such as strong light, achieving system-level protection and greatly improving the reliability and lifespan of the equipment.

[0040] In an alternative implementation, see [reference] Figure 2 This embodiment provides an optical sensing system that integrates the charge pump overcurrent detection circuit described in the above embodiment.

[0041] The core of this system is a SPAD array, with each SPAD connected to a quenching circuit (such as transistor MN0), forming a basic SPAD operating model. The charge pump overcurrent detection circuit of this application provides the high bias voltage required for the operation of the SPAD array.

[0042] When the ambient light intensity is normal, the system operates normally. If a sudden burst of strong light causes a large number of SPADs to avalanche simultaneously, the charge pump load current surges. At this time, the detection circuit of this application quickly detects the excessive input power current and, through the control module, causes the charge pump to pull its output voltage down below the SPAD's breakdown voltage within a very short time. This forces all SPADs to stop avalanching, the current is cut off, thus protecting the entire SPAD array and charge pump from burnout. After the strong light condition disappears, the digital control module can control the charge pump to restore its output voltage, and the system returns to normal operation.

[0043] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In addition, the terms "first", "second", "third", etc. are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0044] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The protection scope of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the scope of the technology disclosed in this application; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application. All should be covered within the protection scope of this application. Therefore, the protection scope of this application should be determined by the protection scope of the claims.

Claims

1. A charge pump overcurrent detection circuit, characterized in that, Includes a charge pump, a detection module, and a control module; The detection module is used to detect the input power current of the charge pump and output an overcurrent indication signal; The control module is used to receive the overcurrent indication signal and output an adjustment signal; The charge pump is used to reduce its output voltage from the initial operating voltage to the target operating voltage in response to the adjustment signal; The detection module includes: A current detection unit is used to convert the input power supply current into a detection voltage; The comparison unit is used to compare the detected voltage with the reference voltage and generate the overcurrent indication signal.

2. The charge pump overcurrent detection circuit according to claim 1, characterized in that, The detection module also includes: A filtering unit is connected between the current detection unit and the comparison unit, and is used to filter the detected voltage.

3. The charge pump overcurrent detection circuit according to claim 1, characterized in that, The current detection unit includes a high-speed current detection amplifier; the comparison unit includes a high-speed comparator.

4. The charge pump overcurrent detection circuit according to claim 2, characterized in that, The filtering unit includes an RC filter, and the filtering bandwidth is adjustable.

5. The charge pump overcurrent detection circuit according to claim 1, characterized in that, The detection module further includes: a generation module; The generation module is used to generate a reference voltage with an adjustable voltage value.

6. The charge pump overcurrent detection circuit according to claim 5, characterized in that, The generation module includes: The core circuit of the bandgap reference is used to generate a reference voltage; A level shifter or voltage divider network is connected to the output of the bandgap reference core circuit to make the value of the reference voltage adjustable.

7. The charge pump overcurrent detection circuit according to claim 5, characterized in that, The generation module includes a digital-to-analog converter for receiving digital configuration signals and directly outputting the reference voltage.

8. The charge pump overcurrent detection circuit according to claim 1, characterized in that, The control module includes digital logic circuitry for generating the adjustment signal in digital form based on the overcurrent indication signal.

9. An optical sensing system, characterized in that, include: Single-photon avalanche diode array; A quenching circuit is connected to the single-photon avalanche diode array; And a charge pump overcurrent detection circuit as described in any one of claims 1-8, used to provide a bias voltage for the single-photon avalanche diode array and to achieve overcurrent protection.

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