High speed AFE for current monitoring applications

Abstract

Embodiments of the present disclosure relate to high-speed AFEs for current monitoring applications. A current monitoring circuit, comprising: an output terminal configured to be coupled to a controller; an inverter having an output coupled to the output terminal; a first transimpedance amplifier having a first input configured to be coupled across a sense resistive element and a second input, and having an output coupled to an input of the inverter; and a current generator having a second transimpedance amplifier configured to generate a reference current at an output of the current generator based on a reference voltage, the output of the current generator coupled to the input of the inverter, wherein the output of the inverter is configured to be in a first state when a load current flowing through the sense resistive element is above a predetermined threshold, and in a second state when the load current is below the predetermined threshold, and wherein the predetermined threshold is based on the reference current.

Description

Technical Field

[0001] This disclosure generally relates to electronic systems and methods, and in particular embodiments, to a high-speed analog front-end (AFE) for current monitoring applications. Background Technology

[0002] Many electronic circuits use current sensing for a variety of different purposes. For example, amplifiers and drivers (such as motor drivers, speaker drivers, hard disk drives, and other drives) often include current sensing to perform one or more functions. For instance, some electronic circuits monitor the current flowing through a load to regulate the current flowing through the load to a specific value. An example of such circuitry is a light-emitting diode (LED) driver. Some electronic circuits measure the current flowing through the load and provide a signal to a controller indicating the magnitude of the measured current, for example, for further processing. Some electronic circuits monitor the current flowing through the load as part of an overcurrent protection circuit, where the overcurrent protection circuit provides an indication of an overcurrent event when the current flowing through the load exceeds a threshold.

[0003] Figure 1 A schematic diagram of an exemplary overcurrent protection circuit 100 is shown. The overcurrent protection circuit 100 includes a sensing resistor R. sense Amplifier 102 and comparator 104. During normal operation, current I0 flows through sensing resistor R. sense And across resistor R sense A voltage proportional to the current I0 is generated. (Across R) sense The voltage is amplified by amplifier 102. Comparator 104 compares the amplified voltage with the reference voltage V. REF The comparison is made based on whether the amplifier voltage is higher or lower than the reference voltage V. REF And generate logical output. Summary of the Invention

[0004] According to one embodiment, a current monitoring circuit includes: an output terminal configured to be coupled to a controller; an inverter having an output coupled to the output terminal; a first transconductance amplifier having a first input and a second input configured to be coupled across a sensing resistive element, and having an output coupled to the input of the inverter; and a current generator having a second transconductance amplifier configured to generate a reference current at the output of the current generator based on a reference voltage, the output of the current generator being coupled to the input of the inverter, wherein the output of the inverter is configured to be in a first state when the load current flowing through the sensing resistive element is higher than a predetermined threshold, and in a second state when the load current is lower than the predetermined threshold, and wherein the predetermined threshold is based on the reference current.

[0005] According to one embodiment, a method includes: receiving an input voltage using a first transconductance amplifier, the input voltage indicating a load current flowing through a resistive element; generating a first current in the input of an inverter, the first current being based on the input voltage; receiving a reference voltage using a second transconductance amplifier; generating a reference current in the input of the inverter, the reference current being based on the reference voltage; setting the output of the inverter to a first state when the first current is higher than the reference current; and setting the output of the inverter to a second state when the first current is lower than the reference current.

[0006] According to one embodiment, an integrated circuit includes: a controller; an inverter having an output coupled to the controller; a first transconductance amplifier having a first input and a second input configured to be coupled across a sensing resistive element, and having an output coupled to the input of the inverter; and a current generator having a second transconductance amplifier configured to generate a reference current at the output of the current generator based on a reference voltage, the output of the current generator being coupled to the input of the inverter, wherein the output of the inverter is configured to be in a first state when the load current flowing through the sensing resistive element is higher than a predetermined threshold, and in a second state when the load current is lower than the predetermined threshold, and wherein the predetermined threshold is based on the reference current. Attached Figure Description

[0007] To gain a more complete understanding of the invention and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:

[0008] Figure 1 A schematic diagram of an exemplary overcurrent protection circuit is shown;

[0009] Figure 2 A schematic diagram of a current monitoring circuit according to an embodiment of the present invention is shown;

[0010] Figure 3 and Figure 4 An embodiment of the present invention is shown. Figure 2 A schematic diagram of a possible implementation of a current monitoring circuit;

[0011] Figure 5A and Figure 5B A schematic diagram of a current monitoring circuit suitable for high-side current sensing according to an embodiment of the present invention is shown;

[0012] Figure 6 A half-bridge with high-side and low-side current sensing is shown according to an embodiment of the present invention;

[0013] Figure 7 A schematic diagram of a current monitoring circuit with hysteresis according to an embodiment of the present invention is shown; and

[0014] Figure 8 An electronic device according to an embodiment of the present invention is shown.

[0015] Unless otherwise indicated, corresponding reference numerals in different figures generally refer to corresponding parts. The figures are drawn to clearly illustrate relevant aspects of the preferred embodiments and are not necessarily drawn to scale. Detailed Implementation

[0016] The manufacture and use of the disclosed embodiments are discussed in detail below. However, it should be understood that the present invention provides many applicable inventive concepts that can be implemented in various specific contexts. The specific embodiments discussed are merely illustrative of particular ways of making and using the invention and do not limit the scope of the invention.

[0017] The following description illustrates various specific details to provide a thorough understanding of several exemplary embodiments according to this description. Embodiments may be obtained without one or more specific details or by utilizing other methods, components, materials, etc. In other instances, known structures, materials, or operations are not shown or described in detail so as not to obscure different aspects of the embodiments. References to "embodiment" in this description indicate that a particular configuration, structure, or feature described with respect to an embodiment is included in at least one embodiment. Therefore, phrases such as "in one embodiment" that may appear at different points in this description do not necessarily refer precisely to the same embodiment. Furthermore, in one or more embodiments, particular forms, structures, or features may be combined in any suitable manner.

[0018] Embodiments of the invention will be described in the specific context of an AFE for current monitoring, which is capable of high-side and low-side current sensing in, for example, a power management integrated circuit (PMIC) (such as in a power management application-specific integrated circuit (ASIC)). Embodiments of the invention can also be used, for example, in overcurrent protection circuits for drivers (such as motor drivers, printer inkjet head drivers, and other drivers), and can be used in any other circuitry that can benefit from rapid overcurrent detection.

[0019] In one embodiment of the invention, the AFE monitors the current flowing through the sensing resistor (also referred to as a shunt resistor) by converting the voltage across the sensing resistor into a monitoring current using a first transconductance amplifier. A second transconductance amplifier is used to convert a reference voltage into a reference current. The monitoring current and the reference current are injected into a high-impedance node coupled to the input of an inverter. When the monitoring current is higher than the reference current, the inverter output is high. When the monitoring current is lower than the reference current, the inverter output is low. The output of the inverter can be used to indicate an overcurrent event. By injecting the monitoring current and the sensing current into the high-impedance node, the comparison between the monitoring current and the reference current can be performed at high speed.

[0020] Figure 2 A schematic diagram of a current monitoring circuit 200 according to an embodiment of the present invention is shown. The current monitoring circuit 200 includes an AFE, which includes a transconductance amplifier 202, a current generator 204, and an inverter 206.

[0021] During normal operation, the transconductance amplifier senses the resistor R across the sensing resistor. sense The voltage is used to sense the current I0. The transconductance amplifier 202 then... c Generating and across sensing resistor R sense The voltage is proportional to the current I (e.g., pull-down). TA Current generator 204 at node V c Generate (e.g., pull up) a reference current I ref When the reference current I ref Higher than current I TA At that time, node V c It is pulled up, and the inverter 206 outputs low. Conversely, when the reference current I... ref Below current I TA At that time, node V c The inverter 206 is pulled down and its output is high. Therefore, the inverter output sends a signal to inform the current I. TA Is it higher or lower than the reference current I? ref Due to current I TA With the sensing resistor R sense The voltage is proportional to the voltage across the sensing resistor R. sense The voltage is proportional to the current I0, therefore the output of inverter 206 indicates whether the current I0 is higher or lower than a predetermined threshold (where the predetermined threshold is based on a reference current I). ref , sensing resistor R sense (The resistance and gain of transconductance amplifier 202).

[0022] like Figure 2 As shown, node V c It is the high-impedance node used as the input of inverter 206. Because there is only one high-impedance node, and the transconductance amplifier 202 operates in open-loop mode, the entire AFE has a wide bandwidth, thus enabling it to work with devices such as... Figure 1 Compared to the closed-loop circuit shown, it achieves a faster response time and has no stability issues.

[0023] The fast response time of the current monitoring circuit 200 advantageously allows for very rapid detection of a current I0 crossing a predetermined threshold. The current flowing through R... senseFurthermore, the delay between the current I0 crossing a predetermined threshold and the output of the inverter 206 changing state (e.g., from high to low or from low to high) can vary based on the technology node. For example, in some embodiments, this delay is on the order of nanoseconds. For instance, in embodiments using a 0.16μm technology platform, this delay can be between 30ns and 40ns.

[0024] The controller 208 can use the output of the inverter 206 for various purposes. For example, in some embodiments, the controller 208 can generate a signal to indicate that the current I0 is above a predetermined threshold. This signal can be, for example, the output of an interrupt pin, which, for example, changes the state of a register bit. In some embodiments, such as when the controller 208 is part of an overcurrent protection circuit, the controller 208 can cause the circuit generating the current I0 to shut down or reduce its power, for example, to protect the circuit.

[0025] Inverter 206 can be implemented in any manner known in the art. In some embodiments, different logic circuitry may be used instead of inverter 206. For example, in some embodiments, a buffer (with a suitable change in polarity) may be used instead of inverter 206. In other embodiments, a comparator similar to comparator 104 may be used instead of inverter 206 (where the reference voltage of such comparator may be set, for example, to ground and the supply voltage V). dd (The midpoint between). Other implementation methods are also possible.

[0026] The controller 208 can be implemented in any manner known in the art. For example, the controller 208 can be implemented as a general-purpose processor, controller, or digital signal processor (DSP) that includes, for example, combinational circuitry coupled to a memory. In some embodiments, the controller 208 can be implemented as a custom application-specific integrated circuit (ASIC). Other implementations are also possible.

[0027] For example, a transconductance amplifier can be used ( Figure 2 (Not shown) Implement a current generator 204. For example, a transconductance amplifier can be used to convert the reference voltage V... ref Convert to reference current I ref In some embodiments, the transconductance amplifiers of current generator 204 and transconductance amplifier 202 are manufactured in the same process steps. By manufacturing the transconductance amplifiers simultaneously using the same process steps, process variations can be similarly applied to both transconductance amplifiers. Therefore, any shift in the performance of transconductance amplifier 202 due to process variations can be compensated for by a similar shift in the transconductance amplifier of current generator 204. Thus, the transconductance amplifier is used to generate the reference current I. ref Advantageously allows for precise setting of a predetermined threshold that causes the inverter 206 to flip.

[0028] Figure 3 A schematic diagram of a current monitoring circuit 300 according to an embodiment of the present invention is shown. The current monitoring circuit 300 is a possible implementation of the current monitoring circuit 200, wherein the transconductance amplifier 302 is a possible implementation of the transconductance amplifier 202, and the current generator 304 is a possible implementation of the current generator 204.

[0029] During normal operation, terminal V in+ and V in- Receive voltage V respectively in+ and V in- Terminal V in+ and V in- For example, across resistor R sense Coupling, such as Figure 2 As shown in the image.

[0030] like Figure 3 As shown, transistors 318 and 316 receive voltage V at their respective gates. in+ and V in- Voltage V in+ and V in- The magnitude of the difference between them determines the current I flowing through transistor 322. meas Current I meas Then it is mirrored to the monitoring current I. mon In some embodiments, the current I mon The magnitude is given by the following formula:

[0031]

[0032] Where the current I b This is the bias current. It should be understood that, for example, it can be changed... Figure 3 The ratio of the current mirrors shown (such as the current mirrors formed by transistors 322 and 324) is used to modify the monitoring current I as described in Equation 1. mon With voltage V in+ and V in- The relationship between them.

[0033] During normal operation, terminal V ref Received reference voltage V ref And amplifier 332 forces current The current flows through transistors 328 and 330. The current flowing through transistor 330 is replicated in transistor 326 to generate the reference current I. ref In some embodiments, the reference current I ref It is given by the following formula:

[0034]

[0035] It should be understood that, for example, this can be achieved by changing... Figure 3 The ratio of the current mirrors shown (such as the current mirrors formed by transistors 328 and 326) is used to modify the reference current I as described in Equation 2. ref and reference voltage V ref The relationship between them.

[0036] like Figure 3 As shown, when the reference current I ref Greater than the monitoring current I mon At that time, node V c The reference current is high, which causes the inverter 206 output to be low. When the reference current I... ref Below the monitoring current I mon At that time, node V c The value is low, which makes the output of inverter 206 high.

[0037] Current generators 306 and 308 generate bias currents for different portions of the bias current monitoring circuit 300. Current generators 206 and 208 can be implemented in any manner known in the art.

[0038] Transistors 312, 314, 316, 318, 320, 322, 326, and 328 may be implemented in any manner known in the art. For example, in some embodiments, transistors 312, 314, 316, 318, 320, 322, 326, and 328 are metal-oxide-semiconductor field-effect transistors (MOSFETs).

[0039] Amplifier 332 may be implemented in any manner known in the art. For example, in some embodiments, amplifier 332 may be implemented as a comparator.

[0040] Figure 4 A schematic diagram of a current monitoring circuit 400 according to an embodiment of the present invention is shown. The current monitoring circuit 400 is another possible implementation of the current monitoring circuit 200. The current monitoring circuit 400 operates in a similar manner to the current monitoring circuit 300. However, the current monitoring circuit 400 utilizes a current generator 404 instead of the current generator 304 to implement the current generator 204.

[0041] like Figure 4 As shown, a current generator 404 is implemented using a transconductance amplifier, which has a coupling to terminal V. ref+ and V ref- The differential input is used to receive the differential reference voltage V respectively. ref+ and V ref- (In contrast to current generator 304, current generator 304 has a reference voltage V) ref(single-ended input). Equation 2 also applies to the current generator 404, where V ref =V ref+ -V ref- In some embodiments, terminal V ref- It can be connected to ground.

[0042] Current monitoring circuits 300 and 400 are suitable for low-side current sensing (e.g., as...) Figure 2 (as shown in the image). Figure 5A A schematic diagram of a current monitoring circuit 500 suitable for high-side current sensing according to an embodiment of the present invention is shown. Figure 5A As shown, the hardware implementation of the current monitoring circuit 500 is very similar to or the same as that of the current monitoring circuit 400. However, the current monitoring circuit 500 has a terminal V that is coupled to the differential input of the transconductance amplifier of circuit 404. in+ and V in- And terminal V ref+ and V ref- The differential input is coupled to the transconductance amplifier 302.

[0043] Figure 5B A schematic diagram of a current monitoring circuit 500 coupled to a high-side sensing resistor according to an embodiment of the present invention is shown. In some embodiments, the supply voltage V cc It can be connected to the power supply voltage V dd Same. In other embodiments, the supply voltage V cc It can be connected to the power supply voltage V dd Different (higher or lower).

[0044] from Figure 4 and Figure 5A It can be seen that the same current monitoring circuit design can be implemented in the same integrated circuit to perform high-side current sensing and low-side current sensing. For example, Figure 6 A half-bridge 600 with high-side current sensing and low-side current sensing is illustrated according to an embodiment of the present invention. The half-bridge 600 may be, for example, a Class AB amplifier half-bridge. Figure 6 As shown, current monitoring circuits 400 and 500 are used for low-side current sensing and high-side current sensing, respectively.

[0045] In some embodiments, hysteresis can be used to implement any of the current monitoring circuits 200, 300, 400, or 500. For example, Figure 7 A schematic diagram of a current monitoring circuit 700 with hysteresis according to an embodiment of the present invention is shown. Figure 7 As shown, the current monitoring circuit 700 includes a controllable current generator 702.

[0046] During normal operation, when the output of inverter 206 is low, current generator 702 is off, current generator 703 is on, and hysteresis current I is delayed. h Added to I ref When the output of inverter 206 is high (e.g., due to current I...), mon Becomes higher than the reference current I ref+ I h Current generator 703 is turned off, current generator 702 is turned on, and the hysteresis current I... h In the dropdown node V c Added to current I mon This produces a hysteresis effect. The amount of hysteresis is based on the hysteresis current I. h The magnitude. Although Figure 7 This shows the current (e.g., I0) flowing through current generators 702 and 703 when the respective current generators 702 and 703 are turned on. h While the currents flowing through current generators 702 and 703 are equal, in some embodiments, the currents flowing through current generators 702 and 703 may be different. For example, in some embodiments, the current flowing through current generator 702 when it is turned on may be higher than the current flowing through current generator 703 when it is turned on. In other embodiments, the current flowing through current generator 702 when it is turned on may be lower than the current flowing through current generator 703 when it is turned on.

[0047] Although current monitoring circuit 700 is shown relative to low-side sensing, it should be understood that high-side sensing current monitoring circuits such as current monitoring circuit 600 can also implement hysteresis in a similar manner. Adding hysteresis to current monitoring circuits (such as current monitoring circuits 200, 300, 400, 500, or 600) advantageously allows for the avoidance of possible oscillations that might be caused by a reference current I. ref Basically equal to the monitored current I mon cause.

[0048] Figure 8 An electronic device 800 according to an embodiment of the present invention is shown. The electronic device 800 includes an application printed circuit board (PCB) 802, an ASIC PCB 806, and a flexible PCB 804. The application PCB 802 includes circuitry 808. The ASIC PCB 806 includes an ASIC 810.

[0049] like Figure 8 As shown, the current monitoring circuit 812 uses a sensing resistor R senseThe current from circuit 808 is sensed via flexible PCB 804. For example, current monitoring circuit 812 can be implemented using current monitoring circuits 200, 300, 400, or 700. Using current monitoring circuits (such as current monitoring circuits 200, 300, 400, or 700) advantageously allows for the accurate determination of overcurrent events at high speed, even when the load generating the monitored current is located on a different PCB from the current monitoring circuit.

[0050] Although the current monitoring circuit 812 is shown as a low-side current sensing monitoring circuit, it should be understood that a high-side current sensing monitoring circuit (such as current monitoring circuit 500) can also be used in electronic devices such as electronic device 800.

[0051] The ASIC 810 can be implemented in a single package on a monolithic semiconductor substrate. In some embodiments, the ASIC 810 can be implemented on multiple semiconductor substrates packaged in a single package. Other implementations are also possible.

[0052] Exemplary embodiments of the invention are summarized herein. Other embodiments may also be understood from the entire specification and claims submitted herein.

[0053] Example 1. A current monitoring circuit includes: an output terminal configured to be coupled to a controller; an inverter having an output coupled to the output terminal; a first transconductance amplifier having a first input and a second input configured to be coupled across a sensing resistive element and having an output coupled to the input of the inverter; and a current generator having a second transconductance amplifier configured to generate a reference current at the output of the current generator based on a reference voltage, the output of the current generator being coupled to the input of the inverter, wherein the output of the inverter is configured to be in a first state when a load current flowing through the sensing resistive element is higher than a predetermined threshold, and in a second state when the load current is lower than the predetermined threshold, wherein the predetermined threshold is based on the reference current.

[0054] Example 2. A current monitoring circuit according to Example 1, wherein the first transconductance amplifier comprises: a first transistor having a control terminal coupled to a first input of the first transconductance amplifier; a second transistor having a control terminal coupled to a second input of the first transconductance amplifier; a third transistor having a current path coupled between a first power supply terminal and a current path of the first transistor, wherein the control terminal of the third transistor is coupled to the current path of the second transistor; a fourth transistor having a current path coupled between the first power supply terminal and the current path of the second transistor, wherein the control terminal of the fourth transistor is coupled to the current path of the first transistor; a first resistive element coupled between the current path of the third transistor and the current path of the fourth transistor; and a first current mirror coupled between the current path of the first transistor and the output of the first transconductance amplifier.

[0055] Example 3. A current monitoring circuit according to either Example 1 or 2, wherein the current generator comprises: a second resistive element; a first amplifier having a first input configured to receive the reference voltage and a second input coupled to the second resistive element; a fifth transistor having a current path coupled to the second resistive element and a control terminal coupled to the output of the first amplifier; and a second current mirror coupled between the current path of the fifth transistor and the output of the current generator.

[0056] Example 4. A current monitoring circuit according to any one of Examples 1 to 3, wherein the reference voltage includes a differential reference voltage having a first reference voltage and a second reference voltage, and wherein the current generator includes: a fifth transistor having a control terminal configured to receive the first reference voltage; a sixth transistor having a control terminal configured to receive the second reference voltage; a seventh transistor having a current path coupled to the current path of the fifth transistor and a control terminal coupled to the current path of the sixth transistor; an eighth transistor having a current path coupled to the current path of the sixth transistor and a control terminal coupled to the current path of the fifth transistor; a second resistive element coupled between the current path of the seventh transistor and the current path of the eighth transistor; and a current mirror coupled between the current path of the fifth transistor and the input of the inverter.

[0057] Example 5. A current monitoring circuit according to one of Examples 1 to 4, wherein the second reference voltage is grounded.

[0058] Example 6. A current monitoring circuit according to any one of Examples 1 to 5, wherein the first, second, third and fourth transistors are n-type transistors.

[0059] Example 7. A current monitoring circuit according to any one of Examples 1 to 6, wherein the first state is high and the second state is low.

[0060] Example 8. The current monitoring circuit according to any one of Examples 1 to 7 further includes: the controller, configured to generate a signal indicating an overcurrent event based on the output of the inverter.

[0061] Example 9. The current monitoring circuit according to any one of Examples 1 to 8 further includes: the sensing resistivity element coupled between the first input and the second input of the first transconductance amplifier.

[0062] Example 10. A current monitoring circuit according to any one of Examples 1 to 9, wherein the sensing resistive element comprises a transistor.

[0063] Example 11. A current monitoring circuit according to any one of Examples 1 to 10, wherein the sensing resistive element has a first terminal directly connected to ground.

[0064] Example 12. A current monitoring circuit according to any one of Examples 1 to 11, further comprising a hysteresis current generator coupled to the input of the inverter, wherein the output of the inverter is configured to control the hysteresis current generator.

[0065] Example 13. A method comprising: receiving an input voltage using a first transconductance amplifier, the input voltage indicating a load current flowing through a resistive element; generating a first current in an input of an inverter, the first current being based on the input voltage; receiving a reference voltage using a second transconductance amplifier; generating a reference current in the input of the inverter, the reference current being based on the reference voltage; setting an output of the inverter to a first state when the first current is higher than the reference current; and setting the output of the inverter to a second state when the first current is lower than the reference current.

[0066] Example 14. The method according to Example 13, wherein the resistive element has a first terminal directly connected to ground, the method further comprising: receiving a second input voltage using a third transconductance amplifier, the second input voltage indicating a second load current flowing through the second resistive element, the third transconductance amplifier being identical to the second transconductance amplifier; generating a second current in the input of a second inverter, the second current being based on the second input voltage; receiving a second reference voltage using a fourth transconductance amplifier, the fourth transconductance amplifier being identical to the first transconductance amplifier; generating a second reference current in the input of the second inverter, the second reference current being based on the second reference voltage; setting the output of the second inverter to the first state when the second current is higher than the second reference current; and setting the output of the second inverter to the second state when the second current is lower than the reference current.

[0067] Example 15. An integrated circuit comprising: a controller; an inverter having an output coupled to the controller; a first transconductance amplifier having a first input and a second input configured to be coupled across a sensing resistive element and having an output coupled to the input of the inverter; and a current generator having a second transconductance amplifier configured to generate a reference current at the output of the current generator based on a reference voltage, the output of the current generator being coupled to the input of the inverter, wherein the output of the inverter is configured to be in a first state when a load current flowing through the sensing resistive element is higher than the predetermined threshold, and in a second state when the load current is lower than the predetermined threshold, wherein the predetermined threshold is based on the reference current.

[0068] Example 16. The integrated circuit according to Example 15 further includes: the sensing resistive element coupled between the first input and the second input of the first transconductance amplifier.

[0069] Example 17. An integrated circuit according to one of Examples 15 or 16, wherein the sensing resistive element includes a resistor.

[0070] Example 18. An integrated circuit according to any one of Examples 15 to 17, wherein the sensing resistive element has a terminal directly connected to ground, the integrated circuit further comprising: a second inverter having an output coupled to the controller; a third transconductance amplifier having a first input and a second input configured to be coupled across the second sensing resistive element and having an output coupled to the input of the inverter, the third transconductance amplifier being identical to the second transconductance amplifier, the second sensing resistive element having a terminal coupled to a power supply terminal configured to receive a voltage higher than ground; and a second current generator having a fourth transconductance amplifier configured to generate a second reference current at the output of the second current generator based on a second reference voltage, the output of the second current generator being coupled to the input of the second inverter, wherein the output of the second inverter is configured to be in a first state when a second load current flowing through the second sensing resistive element is higher than a second predetermined threshold, and in a second state when the second load current is lower than the second predetermined threshold, wherein the second predetermined threshold is based on the second reference current.

[0071] Example 19. An integrated circuit according to one of Examples 15 to 18, wherein the first and second transconductance amplifiers are formed during the same manufacturing steps.

[0072] Example 20. An integrated circuit according to any one of Examples 15 to 19, wherein the controller is configured to generate a signal indicating an overcurrent event when the output of the inverter is in the first state.

[0073] Although the invention has been described with reference to illustrative embodiments, this description is not intended to be limiting. Various modifications and combinations of the illustrative embodiments and other embodiments of the invention will be apparent to those skilled in the art from this description. Therefore, it is intended that the appended claims cover any such modifications or embodiments.

Claims

1. A current monitoring circuit, comprising: The output terminal is configured to be coupled to the controller; An inverter having an output coupled to the output terminal; A first transconductance amplifier has a first input and a second input configured to be coupled across a sensing resistive element, and an output coupled to the input of the inverter; as well as A current generator having a second transconductance amplifier configured to generate a reference current at the output of the current generator based on a reference voltage, the output of the current generator being coupled to the input of an inverter, wherein the output of the inverter is configured to be in a first state when the load current flowing through the sensing resistive element is higher than a predetermined threshold, and in a second state when the load current is lower than the predetermined threshold, wherein the predetermined threshold is based on the reference current.

2. The current monitoring circuit according to claim 1, wherein the first transconductance amplifier comprises: A first transistor having a control terminal coupled to the first input of the first transconductance amplifier; The second transistor has a control terminal coupled to the second input of the first transconductance amplifier; The third transistor has a current path coupled between the current path of the first transistor and the first power supply terminal, wherein the control terminal of the third transistor is coupled to the current path of the second transistor. A fourth transistor has a current path coupled between the current path of the second transistor and the first power supply terminal, wherein the control terminal of the fourth transistor is coupled to the current path of the first transistor. A first resistive element is coupled between the current path of the third transistor and the current path of the fourth transistor; as well as A first current mirror is coupled between the current path of the first transistor and the output of the first transconductance amplifier.

3. The current monitoring circuit according to claim 2, wherein the current generator comprises: Second resistive element; The first amplifier has a first input configured to receive the reference voltage and a second input coupled to the second resistive element; The fifth transistor has a current path coupled to the second resistive element and a control terminal coupled to the output of the first amplifier; as well as A second current mirror is coupled between the current path of the fifth transistor and the output of the current generator.

4. The current monitoring circuit of claim 2, wherein the reference voltage includes a differential reference voltage having a first reference voltage and a second reference voltage, and wherein the current generator includes: The fifth transistor has a control terminal configured to receive the first reference voltage; The sixth transistor has a control terminal configured to receive the second reference voltage; The seventh transistor has a current path coupled to the current path of the fifth transistor and a control terminal coupled to the current path of the sixth transistor. The eighth transistor has a current path coupled to the current path of the sixth transistor and a control terminal coupled to the current path of the fifth transistor. A second resistive element is coupled between the current path of the seventh transistor and the current path of the eighth transistor; as well as A current mirror is coupled between the current path of the fifth transistor and the input of the inverter.

5. The current monitoring circuit according to claim 4, wherein the second reference voltage is grounded.

6. The current monitoring circuit according to claim 2, wherein the first transistor, the second transistor, the third transistor and the fourth transistor are n-type transistors.

7. The current monitoring circuit according to claim 1, wherein the first state is high and the second state is low.

8. The current monitoring circuit according to claim 1, further comprising: The controller is configured to generate a signal indicating an overcurrent event based on the output of the inverter.

9. The current monitoring circuit according to claim 1, further comprising: The sensing resistive element is coupled between the first input and the second input of the first transconductance amplifier.

10. The current monitoring circuit of claim 9, wherein the sensing resistive element comprises a transistor.

11. The current monitoring circuit of claim 9, wherein the sensing resistive element has a first terminal directly connected to ground.

12. The current monitoring circuit of claim 1 further includes a hysteresis current generator coupled to the input of the inverter, the output of the inverter being configured to control the hysteresis current generator.

13. A method for a current monitoring circuit, comprising: The input voltage is received using a first transconductance amplifier, the input voltage indicating the load current flowing through the resistive element; A first current is generated at the input of the inverter using a first transconductance amplifier, the first current being based on the input voltage; The reference voltage is received using a second transconductance amplifier; A reference current is generated at the input of the inverter using a second transconductance amplifier, the reference current being based on the reference voltage. When the first current is higher than the reference current, the output of the inverter is in the first state; as well as When the first current is lower than the reference current, the output of the inverter is in the second state.

14. The method of claim 13, wherein the resistive element has a first terminal directly connected to ground, the method further comprising: A second input voltage is received using a third transconductance amplifier, the second input voltage indicating a second load current flowing through a second resistive element, the third transconductance amplifier being the same as the second transconductance amplifier; A second current is generated at the input of the second inverter, the second current being based on the second input voltage; The second reference voltage is received using a fourth transconductance amplifier, which is the same as the first transconductance amplifier. A second reference current is generated at the input of the second inverter, the second reference current being based on the second reference voltage; When the second current is higher than the second reference current, the output of the second inverter is in the first state; as well as When the second current is lower than the reference current, the output of the second inverter is set to the second state.

15. An integrated circuit, comprising: Controller; An inverter having an output coupled to the controller; A first transconductance amplifier has a first input and a second input configured to be coupled across a sensing resistive element, and an output coupled to the input of the inverter; as well as A current generator having a second transconductance amplifier configured to generate a reference current at the output of the current generator based on a reference voltage, the output of the current generator being coupled to the input of an inverter, wherein the output of the inverter is configured to be in a first state when the load current flowing through the sensing resistive element is higher than a predetermined threshold, and in a second state when the load current is lower than the predetermined threshold, wherein the predetermined threshold is based on the reference current.

16. The integrated circuit of claim 15, further comprising: The sensing resistive element is coupled between the first input and the second input of the first transconductance amplifier.

17. The integrated circuit of claim 16, wherein the sensing resistive element comprises a resistor.

18. The integrated circuit of claim 15, wherein the sensing resistive element has a terminal directly connected to ground, the integrated circuit further comprising: A second inverter has an output coupled to the controller; A third transconductance amplifier has a first input and a second input configured to be coupled across a second sensing resistive element, and has an output coupled to the input of the inverter. The third transconductance amplifier is the same as the second transconductance amplifier. The second sensing resistive element has a terminal coupled to a power supply terminal configured to receive a voltage higher than ground. as well as A second current generator has a fourth transconductance amplifier configured to generate a second reference current at the output of the second current generator based on a second reference voltage. The output of the second current generator is coupled to the input of the second inverter, wherein the output of the second inverter is configured to be in the first state when a second load current flowing through the second sensing resistive element is higher than a second predetermined threshold, and in the second state when the second load current is lower than the second predetermined threshold, wherein the second predetermined threshold is based on the second reference current.

19. The integrated circuit of claim 15, wherein the first transconductance amplifier and the second transconductance amplifier are formed during the same manufacturing steps.

20. The integrated circuit of claim 15, wherein the controller is configured to generate a signal indicating an overcurrent event when the output of the inverter is in the first state.

Images