Power monitoring

Abstract

This disclosure relates to power supply monitoring. The disclosed concepts provide circuitry and methods for monitoring a power supply and a bandgap circuit. The power supply is configured to provide a power supply voltage. The bandgap circuit is configured to generate a substantially fixed reference voltage using the power supply voltage. The circuit includes a gain component configured to receive the reference voltage and the power supply voltage, and to provide an output voltage equal to the smaller of the reference voltage multiplied by a gain value and the power supply voltage. Additionally, the circuit includes a comparator circuit configured to provide first information indicating that the reference voltage meets a reference threshold and the power supply voltage meets a power supply threshold in response to the output voltage meeting a trigger value. The comparator circuit is also configured to provide second information indicating that the reference voltage fails to meet the reference threshold and / or the power supply voltage fails to meet a power supply threshold in response to the output voltage failing to meet the trigger value.

Description

Technical Field

[0001] This disclosure generally relates to monitoring power supplies, and more particularly to monitoring power supplies and bandgap circuits. Background Technology

[0002] For many systems, it is important to ensure that the power supply provides a voltage that meets the minimum required threshold to ensure the correct and safe operation of the system. This can be particularly challenging for single-power supply systems, as the circuitry used to monitor the power supply is often powered by that power supply itself. As a result, under certain conditions, the monitoring circuitry may not provide a reliable indication of the power supply status.

[0003] For example, the supply voltage provided by the power source may need to meet a threshold. To ensure this, the supply voltage can be compared to a reference voltage. While this can be done under conditions where the reference voltage can be generated under a wide range of power supply operating conditions, it is generally not guaranteed in all cases. In practice, the circuitry generating the reference voltage may require a minimum supply voltage, the circuitry itself may be faulty, or the circuitry may require time to properly start up and provide a stable output. Of course, the reference voltage itself may be affected by monitoring circuitry, but this further increases cost and suffers from the same problems as monitoring circuitry used for the power supply.

[0004] Therefore, there is a need for improved devices for reliably monitoring power supplies. Summary of the Invention

[0005] According to one aspect, a circuit for monitoring a power supply and a bandgap circuit is provided. The power supply is configured to provide a supply voltage. The bandgap circuit is configured to generate a substantially fixed reference voltage using the supply voltage.

[0006] The circuit includes a gain unit configured to receive a reference voltage and a supply voltage, and to provide an output voltage equal to the smaller of the reference voltage multiplied by a gain value and the supply voltage. Additionally, the circuit includes a comparator circuit configured to provide first information indicating that the reference voltage meets a reference threshold and the supply voltage meets a supply threshold in response to the output voltage meeting a trigger value. The comparator circuit is also configured to provide second information indicating that the reference voltage fails to meet the reference threshold and / or the supply voltage fails to meet the supply threshold in response to the output voltage failing to meet the trigger value.

[0007] According to another aspect of this disclosure, a method for monitoring a power supply voltage and a bandgap circuit is provided. The power supply is configured to provide a power supply voltage, and the bandgap circuit is configured to generate a substantially fixed reference voltage using the power supply voltage.

[0008] The method includes: providing an output voltage equal to the smaller of a reference voltage multiplied by a gain value and a supply voltage. In response to the output voltage meeting a trigger value, the method provides first information indicating that the reference voltage meets a reference threshold and the supply voltage meets a supply threshold. In response to the output voltage failing to meet the trigger value, the method provides second information indicating that the reference voltage fails to meet the reference threshold and / or the supply voltage fails to meet the supply threshold.

[0009] Those skilled in the art will recognize the additional features and advantages upon reading the following detailed description and viewing the accompanying drawings. Attached Figure Description

[0010] The invention will now be described by way of example with reference to the accompanying drawings, in which:

[0011] Figure 1 Existing technology circuits for monitoring power supplies and bandgap circuits are presented;

[0012] Figure 2 A circuit for monitoring power supply and bandgap circuitry according to an embodiment is presented;

[0013] Figure 3 Depicting the rapid startup of a power supply or the slow startup of a bandgap circuit. Figure 2 Example response of the circuit;

[0014] Figure 4 Depicting the slow startup period of the power supply Figure 2 Example response of the circuit;

[0015] Figure 5 A circuit for monitoring power supply and bandgap circuitry according to another embodiment is presented;

[0016] Figure 6 Circuit diagrams of open-loop bandgap (OLBG) circuits according to aspects of embodiments are presented; and

[0017] Figure 7 A flowchart of a method for monitoring power supplies and bandgap circuits is presented.

[0018] It should be noted that these figures are schematic and not drawn to scale. For clarity and convenience in the figures, the relative dimensions and scales of these figures have been enlarged or reduced. Detailed Implementation

[0019] The following description illustrates exemplary aspects of this disclosure. However, it should be understood that this description is not intended to be a limitation on the scope of this disclosure. Rather, the description also covers combinations and modifications of those exemplary aspects described herein.

[0020] The disclosed concepts relate to the monitoring of a power supply and a bandgap circuit powered by that power supply. Specifically, embodiments involve monitoring the amplitude of a power supply voltage generated by the power supply and the amplitude of a substantially fixed reference voltage generated by the bandgap circuit. For this purpose, an output voltage equal to the smaller of the reference voltage multiplied by a gain value and the power supply voltage is generated. If the output voltage is equal to or greater than a trigger value, two points are determined: (i) the reference voltage meets a reference threshold; and (ii) the power supply voltage meets a power supply threshold. Alternatively, if the output voltage is less than the trigger value, either (or both) points are determined: (i) the reference voltage fails to meet the reference threshold; and (ii) the power supply voltage fails to meet the power supply threshold.

[0021] In other words, if the minimum of the reference voltage multiplied by the gain and the supply voltage fails to meet the trigger value, it is inferred that at least one of the reference voltage and the supply voltage has fallen below their predefined threshold. Therefore, this provides a simple method for inferring whether at least one of the power supply and the bandgap circuitry has failed to generate sufficient voltage (e.g., due to damage, malfunction, unusual operating conditions, etc.). This information can then be used to determine whether to activate the power-powered system to notify the user or system to perform further diagnostics, or to notify the system or user to repair the problem.

[0022] For clarity, a bandgap circuit is a voltage reference circuit that uses the supply voltage to generate a near-constant voltage. That is, regardless of potential fluctuations in the supply voltage, electrical load, temperature, etc., a bandgap circuit can generate a near-constant voltage. Therefore, a bandgap circuit can be used to determine whether the supply voltage meets a threshold (e.g., by comparing the reference voltage generated by the bandgap circuit with the supply voltage).

[0023] However, the reference voltage may be incorrect at startup of the bandgap circuit (i.e., it may be unstable for a period of time after the bandgap circuit is initially turned on / powered). Furthermore, the reference voltage may be unstable if the supply voltage is excessively low. Additionally, if the bandgap circuit is damaged, such as due to overheating, exposure to overcurrent, or excessive force, it may output an unexpected reference voltage. Therefore, there are situations where the bandgap circuit may generate an unexpected reference voltage. Consequently, there is a possibility that monitoring the supply voltage based on the reference voltage may be incorrect. In other words, monitoring based on the reference voltage generated by the bandgap circuit may be unreliable.

[0024] Therefore, the proposed embodiment combines the comparison of the supply voltage and the reference voltage with the trigger level. If the reference voltage or the supply voltage scaled by the gain value fails to meet the trigger value, it can be inferred that one of the supply voltage or the reference voltage does not meet its corresponding threshold.

[0025] Therefore, this disclosure provides a circuit for monitoring a power supply configured to provide a power supply voltage. The power supply can be any electrical device configured to supply power to an electrical load. The power supply ideally provides a power supply voltage with an amplitude within a predetermined range, although this may be affected by the connected loads and other operating conditions. The power supply voltage can provide a DC voltage that is substantially stable over time (i.e., non-alternating).

[0026] The circuit also monitors a bandgap circuit configured to generate a substantially constant reference voltage using the supply voltage. That is, the bandgap circuit generates a near-constant voltage with minute variations due to changes in the supply, electrical load, or temperature. The supply is used to power the bandgap circuit, and due to the nature of the bandgap circuit, the resulting reference voltage is nearly constant regardless of the power supplied. However, the reference voltage may deviate from the expected value due to startup fluctuations, insufficient power supplied by the supply, and / or damage to the bandgap circuit.

[0027] To perform monitoring, the circuit includes a gain unit configured to receive a reference voltage and a supply voltage, and to provide an output voltage equal to the smaller of (i) the reference voltage multiplied by the gain value and (ii) the supply voltage.

[0028] Therefore, the gain unit receives a reference voltage and scales it using a gain value. The gain unit then compares the scaled reference voltage with the supply voltage to determine which voltage is smaller. Based on this comparison, the gain unit provides, generates, or additionally outputs an output voltage equal to the smaller of the scaled reference voltage and the supply voltage.

[0029] The circuit also includes a comparator circuit that receives the output voltage from the gain unit. The comparator circuit compares the output voltage with a trigger value and provides first or second information (e.g., outputting a high-state voltage or a low-state voltage) based on the comparison.

[0030] If the output voltage meets or exceeds the trigger value, the first information is provided by the comparator circuit. That is, if the amplitude of the output voltage is greater than or equal to the trigger value, the comparator circuit will output the first information. The first information indicates that the reference voltage meets the reference threshold and the power supply voltage meets the power supply threshold.

[0031] If the output voltage fails to meet the trigger value, a second message is provided by the comparator circuit. That is, if the output voltage amplitude is less than the trigger value, the comparator circuit will output a second message. This second message indicates that the reference voltage has failed to meet the reference threshold and the power supply voltage has failed to meet the power supply threshold.

[0032] In some embodiments, the first information can be provided in the form of a high-state signal, and the second information can be provided in the form of a low-state signal. For example, the comparator circuit can output a voltage corresponding to "1" as the first information, and can output a voltage corresponding to "0" as the second information. That is, when it is determined that the output voltage meets the trigger value, the comparator circuit can pull the output node high, or when it is determined that the output voltage fails to meet the trigger value, the comparator circuit can pull the output node low. Of course, the opposite of the above can also be true (i.e., the first information can be provided in the form of a low-state signal, and the second information can be provided in the form of a high-state signal).

[0033] A power supply threshold can be the minimum expected amplitude of the power supply voltage. This can be the minimum voltage required to reliably, safely, and / or predictably power a load.

[0034] The reference threshold can be the minimum expected amplitude of the reference voltage. This value can be set to the minimum expected voltage output by the bandgap circuit when operating under expected conditions. That is, this value can be the minimum expected voltage output by the bandgap circuit, given that the bandgap circuit operates in a steady state (i.e., not during startup), has sufficient power supply, and is not damaged.

[0035] In a typical embodiment, the power supply threshold is greater than a reference threshold. In one case, the power supply threshold may be between 1.44V and 1.62V, and the reference threshold may be between 1.05V and 1.15V.

[0036] In some embodiments, the gain value (used to scale the reference voltage) can depend on both the power supply threshold and the reference threshold. That is, the gain value can be set based on both the power supply threshold and the reference threshold. More specifically, the gain value can be equal to the power supply threshold divided by the reference threshold. In this case, the trigger value can be equal to the power supply threshold.

[0037] In certain embodiments, the comparator circuit may include an open-loop bandgap (OLBG) circuit and a comparator.

[0038] An OLBG circuit can be configured to receive an output voltage from a gain unit and generate a first voltage and a second voltage, wherein the difference between the first voltage and the second voltage is based on the output voltage received from the gain unit. In other words, an OLBG can be configured to output two voltages, the difference between which depends on the amplitude of the output voltage.

[0039] The comparator can be configured to output either first information or second information based on the result of a comparison between a first voltage and a second voltage. In other words, if the difference between the first voltage and the second voltage meets (or exceeds) a certain condition, the first information can be output. Alternatively, if the difference between the first voltage and the second voltage fails to meet a certain condition, the second information can be output.

[0040] The combination of the OLBG circuit and the comparator circuit enables the determination of whether the output voltage from the gain unit meets the trigger value without requiring an externally generated reference voltage. In practice, these components are configured to provide a first message if the output voltage meets or exceeds the trigger value, and a second message if the output voltage fails to meet the trigger value. This is primarily facilitated by the OLBG circuit, which generates two voltages, the difference of which is based on the output voltage from the gain unit.

[0041] In other words, because the OLBG circuit does not require an external reference voltage or a power supply voltage (other than the output voltage from the gain unit), the comparator circuit can reliably provide first or second information independent of the power supply voltage condition.

[0042] More specifically, an OLBG circuit may include an input node connected to the output of a gain component.

[0043] The OLBG circuit may include a first branch comprising a first resistor and a second resistor connected in series between an input node and a reference potential node (e.g., ground), and a diode connected in parallel with the second resistor of the first branch between the reference potential node and a first output node. The first output node may be provided between the first and second resistors of the first branch, and the diode may be configured to impede current flow between the reference potential node and the first output node. A first voltage may be provided at the first output node.

[0044] The OLBG circuit may also include a second branch comprising a first resistor and a second resistor connected in series between the input node and the reference potential node. The second branch may further include a diode and a third resistor connected in series, wherein the diode and the third resistor are connected in parallel with the second resistor of the second branch and between the reference potential node and the second output node. The second output node may be provided between the first and second resistors of the second branch. The diode may be configured to impede current flow between the reference potential node and the second output node. In this case, a second voltage may be provided at the second output node.

[0045] Of course, other configurations and modifications to the OLBG circuit can be implemented by those skilled in the art, and additional components can be provided in the OLBG circuit.

[0046] While a comparator circuit including an OLBG circuit and a comparator is ideal, other configurations of the comparator circuit are envisioned.

[0047] By way of example, a comparator circuit may include a voltage divider and a comparator. More specifically, the comparator circuit may include an input node connected to the output of a gain component, and a voltage divider (e.g., a first resistor and a second resistor connected in series) connected between the input node and a reference potential node (e.g., ground). The voltage divider may be configured to provide an output voltage based on the voltage at the input node. The comparator may be configured to output first information or second information based on the result of a comparison between the output voltage from the voltage divider and a comparator reference voltage.

[0048] Of course, this comparator circuit requires a comparator reference voltage that can be generated from another source. However, it should be understood that this comparator circuit still provides a means for monitoring both the supply voltage from the power source and the reference voltage from the bandgap circuit using a single comparator circuit (e.g., without requiring additional components for monitoring the power supply and bandgap circuit). In effect, the voltage divider provides a means for progressively reducing the output voltage from the gain component in a manner that allows for reliable evaluation of the operation of the power supply and bandgap circuit while still operating under low voltage conditions.

[0049] In summary, this disclosure provides an apparatus for monitoring the power supply voltage and a reference voltage from a bandgap circuit (which should be substantially constant independent of power supply voltage fluctuations and temperature conditions) using a simple circuit. Specifically, by providing a gain element that provides an output voltage equal to the smaller of (i) the reference voltage multiplied by a gain value and (ii) the power supply voltage, a single comparator circuit can be provided, which evaluates the output voltage from the gain element to assess whether the power supply and the bandgap circuit are operating as intended.

[0050] To best understand the advantages of the disclosed embodiments, it is useful to understand how the power supply is currently monitored. Figure 1 Such a system is described in the text.

[0051] As shown in the figure, there is a device configured to provide power supply voltage V. Supp Power supply 10. Power supply 10 can be used to provide power to another system. Power supply 10 is connected to bandgap circuit 20. As described above, bandgap circuit 20 uses supply voltage V. Supp Generates a near-constant reference voltage V Ref The voltage reference circuit.

[0052] To monitor the power supply voltage VSupp The amplitude of the voltage is provided by power monitor 30. Power monitor 30 receives V from power supply 10. Supp and V from bandgap circuit 20 Ref Through V Supp With V Ref By comparing, we can determine V Supp Does the minimum requirement meet? If not, the power monitor 30 will indicate a low power level.

[0053] A power-on reset circuit 50 is also provided. The power-on reset circuit 50 ensures V Supp High power is being supplied. That is, power monitor 30 indicates V. Supp Does the minimum power supply level meet the requirements, and does the power-on reset circuit 50 indicate V? Supp Is a high power supply being provided? If both are met, then power supply 10 is providing the appropriate power supply voltage.

[0054] However, if the bandgap circuit 20 fails to provide accurate V Ref If this happens, a problem may arise. This could be due to damage to the bandgap circuit 20, or it could be related to the power supply 10. For example, during the startup of the power supply 10, the bandgap circuit 20 may spend time resolving and providing a stable and accurate V. Ref In some cases, the voltage provided by power supply 10 may be insufficient for V. Ref Stable and accurate generation. In these cases, the provided monitoring system may not be providing enough V. Supp The correct instructions.

[0055] Therefore, a bandgap OK circuit 40 can be provided. This circuit can monitor V. Ref And provide V Ref Whether the indication is accurate and stable. However, it should be understood that this requires additional space, more parts and costs, and is itself prone to error.

[0056] Figure 2 The solution according to the proposed embodiment is described. That is, Figure 2 A circuit for monitoring the power supply 10 and the bandgap circuit 20 according to an embodiment is presented. This circuit can provide an indication of whether the power supply 10 and the bandgap circuit 20 are providing the expected voltage.

[0057] As shown in the figure, the circuit includes a gain component 110 and a comparator circuit 120. The gain component 110 receives power supply V. Supp and reference voltage V RefThe output voltage g(V) is provided to the comparator circuit 120. The comparator circuit 120 receives g(V) and provides either first information or second information.

[0058] Gain component 110 is configured to provide equal to V Ref Multiply by the gain values ​​A and V Supp The smaller of the two, g(V). Therefore, the gain component 110 can first... Ref The gain value is scaled. Then, the gain unit 110 can scale the V... Ref With V Supp It compares the two voltages and outputs the smaller one.

[0059] In response to g(V) satisfying the trigger value, the comparator circuit 120 is configured to provide an indication V. Ref Satisfy reference threshold V trig-ref And V Supp Satisfy power supply threshold V trig-supp The first piece of information. Alternatively, in response to g(V) failing to meet the trigger value, the comparator circuit 120 is configured to provide an indication V. Ref Failed to meet reference threshold V trig-ref and / or V Supp Failed to meet power threshold V trig-supp The second piece of information. Therefore, the output from the comparator circuit 120 indicates whether the bandgap circuit 20 and the power supply 10 are performing as expected.

[0060] In other words, the gain unit 110 can be configured to perform the following: If A V Ref <V Supp Then g(V) = A V Ref Otherwise g(V) = V Ref Where A = V trig_supp / V trig_ref

[0061] Then, the comparator circuit 120 compares g(V) with the trigger value. If g(V) meets or exceeds the trigger value, the comparator circuit 120 can output a first message (e.g., a high value). If g(V) fails to meet the trigger value, the comparator circuit 120 can output a second message (e.g., a low value). The trigger value can be equal to V. trig_supp .

[0062] To demonstrate the operation of this circuit, Figure 3 An exemplary response of the circuit during the rapid startup of power supply 10 is depicted. Similarly, Figure 3The response shown can also be applied to the case of slow startup of the bandgap circuit 20.

[0063] As shown in the figure, power supply 10 starts and V Supp It rises rapidly before stabilizing at the expected amplitude. However, the V output by the bandgap circuit 20... Ref It remains at 0 output because power supply 10 starts up quickly and stabilizes, or because bandgap circuit 20 takes a little time to start up.

[0064] Therefore, g(V) remains at 0 because it is equal to V. Ref A (i.e., 0) or V Supp The lower of the two values. As a result, the output from comparator circuit 120 also remains low (indicating the second information). It is worth noting that in other monitoring circuits, although the bandgap circuit 20 has not yet been activated, it can indicate the lower value at V. Supp More than V Ref The circuit is operating normally at the time.

[0065] After a period of time, the bandgap circuit 20 starts up, and V Ref The voltage begins to rise. Therefore, g(V) also begins to rise. Finally, g(V) reaches the trigger value. When this happens, the output from comparator circuit 120 switches high (indicating the first information).

[0066] After operating for a period of time, the bandgap circuit 20 was damaged, and V Ref The value begins to decrease. Once g(V) drops below the trigger value, the output from comparator circuit 120 switches low (indicating the second information). It is worth noting that in other monitoring circuits, even though the bandgap circuit 20 has been damaged, it can still indicate the value at V. Supp More than V Ref The circuit was operating normally until V Supp Finally, reduce (i.e., power supply 10 is turned off).

[0067] Figure 4 Another example of the circuit's operation is shown below. In this case, power supply 10 starts up slowly and begins to provide sufficient voltage. Supp .

[0068] As shown in the figure, power supply 10 starts and V Supp It rises slowly. Because of this slow rise, V... Ref They also rise almost simultaneously. Therefore, g(V) equals V. Supp Because V Ref A > V Supp .

[0069] After a period of time, VRef It reaches its expected output value. g(V) continues to rise because V... Supp Keep less than V Ref A. It is worth noting that in other monitoring circuits, although V Supp V has not yet been reached trig_supp However, it can be indicated in V Supp More than V Ref The circuit is operating normally at the time.

[0070] Finally, g(V) (still equals V) Supp The trigger value is reached. At this time, the output from comparator circuit 120 switches high (indicating the first information). g(V) continues to rise briefly because V Supp Still less than A V Ref Finally, g(V) stabilizes at A. V Ref Place.

[0071] After a short period of time, power 10 is switched off. Supp It begins to decrease, while V Ref And g(V) remains stable. Finally, V Supp Less than A V Ref And g(V) drops below the trigger level. At this time, the output from comparator circuit 120 switches low (indicating the second information).

[0072] As these cases demonstrate, the monitoring circuitry provides a reliable means of indicating when both the power supply 10 and the bandgap circuit 20 operate as expected, and when at least one of them does not operate.

[0073] Figure 5 A circuit for monitoring the power supply 10 and the bandgap circuit 20 according to another embodiment is presented. The circuit is substantially as follows in operation: Figure 2 The circuit is described in detail below. Therefore, for the sake of brevity, a repeated description of the gain component 110 is omitted. However, in this case, the comparator circuit 120 is implemented in the form of an OLBG circuit 130 and a comparator 140.

[0074] OLBG circuit 130 is configured to receive g(V) from gain component 110 and generate a first voltage and a second voltage. The magnitude of the difference between the generated first voltage and the second voltage is based on g(V). Therefore, the difference between these voltages provides a means for evaluating the magnitude of g(V) without requiring an external reference voltage.

[0075] Comparator 140 is configured to output first information or second information based on the result of a comparison between a first voltage and a second voltage. That is, comparator 140 evaluates the difference between the first voltage and the second voltage from OLBG circuit 130 and outputs first information or second information based on that difference. For example, if the difference exceeds a certain threshold, first information can be provided, and if the difference does not exceed a certain threshold, second information can be provided (or vice versa).

[0076] Figure 6 It can be presented Figure 5 The circuit diagram of the OLBG circuit 130 implemented in the circuit.

[0077] As shown in the figure, the OLBG circuit 130 includes an input node 131 connected to the output of the gain component 110. Therefore, the input node 131 receives g(V). The OLBG circuit 130 includes a first branch for providing a first voltage V1 at a first output node 132 and a second branch for providing a second voltage V2 at a second output node 133.

[0078] The first branch includes a first resistor 134a, a second resistor 135a, and a diode 136a. The first resistor 134a and the second resistor 135a are connected in series between the input node and ground. The diode 136a is connected in parallel with the second resistor 135a between ground and the first output node 132. The first output node 132 is provided between the first resistor 134a and the second resistor 135a. That is, the diode 136a and the second resistor 135a are arranged in parallel between the first output node 132 and ground. The diode 136a is arranged to impede the current flow between ground and the first output node 132.

[0079] The second branch includes a first resistor 134b, a second resistor 135b, a third resistor 137, and a diode 136b. The first resistor 134b and the second resistor 135b are connected in series between the input node and ground. The diode 136b and the third resistor 137 are connected in series and arranged in parallel with the second resistor 135b between ground and the second output node 133. The second output node 133 is provided between the first resistor 134b and the second resistor 135b in the second branch. The diode 136b is arranged to impede the current flow (via the third resistor 137) between ground and the second output node 133.

[0080] The resistance of the first resistor 134a in the first branch and the resistance of the first resistor 134b in the second branch can be the same. The resistance of the second resistor 135a in the first branch and the resistance of the second resistor 135b in the second branch can also be the same. The circuit trigger point of the OLBG circuit 130 can be defined as when the first voltage and the second voltage are equal. That is, if the voltage at input node 131 (i.e., g(V)) is equal to a predetermined voltage, then the first voltage and the second voltage can be equal. This predetermined voltage can be defined by the ratio of the resistances of the first resistors 134a and 134b to the resistance of the third resistor 137.

[0081] Therefore, these resistors can be selected such that the difference between the first and second voltages is negative when g(V) is less than the trigger value, and positive when g(V) is equal to or greater than the trigger value (and vice versa). Thus, comparator 140 can be configured to provide appropriate first and second information.

[0082] Figure 7 A flowchart illustrating a method for monitoring a power supply and a bandgap circuit is presented. As described above, the power supply is configured to provide a supply voltage. The bandgap circuit is configured to generate a substantially fixed reference voltage using the supply voltage.

[0083] In step 210, an output voltage equal to the smaller of the reference voltage from the bandgap circuit multiplied by the gain value and the supply voltage is provided. For this purpose, a subset of the reference voltage multiplied by / scaled by the gain value can be provided before a comparison between the scaled reference voltage and the supply voltage is used to determine the smaller of the two.

[0084] The gain value can depend on the supply threshold (indicating the minimum expected amplitude of the supply voltage) and the reference threshold (indicating the minimum expected amplitude of the threshold voltage). Specifically, the gain value can be equal to the supply threshold divided by the reference threshold. The supply threshold can be greater than the reference threshold.

[0085] In step 220, it is determined whether the output voltage provided in step 210 meets the trigger value. That is, it is determined whether the amplitude of the output voltage is greater than or equal to the trigger value. If yes, the method proceeds to step 230. If not, the method proceeds to step 240.

[0086] In step 230, first information is provided / output. The first information indicates that the reference voltage meets the reference threshold and the supply voltage meets the supply threshold. That is, the first information indicates that both the supply and the bandgap circuit are operating as expected.

[0087] In step 240, second information is provided / output. The second information indicates that the reference voltage fails to meet the reference threshold and / or the power supply voltage fails to meet the power supply threshold, that is, at least one (or both) of the power supply and the bandgap circuit is providing an unexpected voltage.

[0088] Steps 210-240 can be repeated iteratively as the power supply voltage and reference voltage change. Therefore, the power supply voltage and threshold voltage can be continuously monitored to ensure they meet requirements.

[0089] Although specific examples have been illustrated and described herein, those skilled in the art will understand that various alternatives and / or equivalent embodiments may be substituted for the specific examples shown and described without departing from the scope of the invention. This application is intended to cover any modifications or variations of the specific examples discussed herein. Therefore, the invention is defined only by the claims and their equivalents.

[0090] It should be noted that the methods and apparatuses, including those with preferred embodiments outlined in this document, can be used alone or in combination with other methods and apparatuses disclosed in this document. Furthermore, features outlined in the context of the apparatus also apply to the corresponding methods, and vice versa. Moreover, all aspects of the methods and apparatuses outlined in this document can be combined arbitrarily. In particular, the features of the claims can be combined with each other in any manner.

[0091] It should be noted that the description and accompanying drawings are merely illustrative of the principles of the proposed methods and systems. Those skilled in the art will be able to implement various arrangements, which, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope. Furthermore, all examples and embodiments outlined in this document are primarily intended for illustrative purposes only to aid the reader in understanding the principles of the proposed methods and systems. Moreover, all statements regarding the principles, aspects, and embodiments of the invention provided herein, as well as specific examples thereof, are intended to cover their equivalents.

[0092] The following embodiments are disclosed:

[0093] 1. A circuit for monitoring a power supply configured to provide a power supply voltage, and for monitoring a bandgap circuit configured to generate a substantially fixed reference voltage using the power supply voltage, the circuit comprising: A gain unit is configured to receive a reference voltage and a supply voltage, and to provide an output voltage equal to the reference voltage multiplied by the smaller of the gain value and the supply voltage; and The comparator circuit is configured as follows: In response to the output voltage meeting the trigger value, first information indicating that the reference voltage meets the reference threshold and the power supply voltage meets the power supply threshold is provided; and In response to the output voltage failing to meet the trigger value, second information is provided indicating that the reference voltage fails to meet the reference threshold and / or the power supply voltage fails to meet the power supply threshold.

[0094] 2. The circuit according to Embodiment 1, wherein the gain value depends on the power supply threshold and the reference threshold.

[0095] 3. The circuit according to Embodiment 2, wherein the gain value is equal to the power supply threshold divided by the reference threshold.

[0096] 4. The circuit according to any one of embodiments 1-3 further includes a bandgap circuit configured to generate a substantially fixed reference voltage using a power supply voltage.

[0097] 5. The circuit according to any one of embodiments 1-4, wherein the power supply threshold is greater than the reference threshold.

[0098] 6. The circuit according to any one of embodiments 1-5, wherein the comparison circuit includes: An open-loop bandgap (OLBG) circuit is configured to receive an output voltage from a gain component and generate a first voltage and a second voltage, wherein the difference between the first voltage and the second voltage is based on the output voltage received from the gain component; and The comparator is configured to output first information or second information based on the result of a comparison between a first voltage and a second voltage.

[0099] 7. The circuit according to Embodiment 6, wherein the OLBG circuit includes: The input node is connected to the output of the gain unit; The first branch includes a first resistor and a second resistor connected in series between the input node and the reference potential node, and a diode connected in parallel with the second resistor of the first branch and between the reference potential node and the first output node. The first output node is provided between the first resistor and the second resistor of the first branch. The diode is configured to impede the current flow between the reference potential node and the first output node, wherein a first voltage is provided on the first output node.

[0100] The second branch includes a first resistor and a second resistor connected in series between the input node and the reference potential node, and a diode and a third resistor connected in series. The diode and the third resistor are connected in parallel with the second resistor of the second branch and are located between the reference potential node and the second output node, which is provided between the first resistor and the second resistor of the second branch. The diode is configured to impede the current flow between the reference potential node and the second output node, wherein a second voltage is provided at the second output node.

[0101] 8. The circuit according to any one of embodiments 1-5, wherein the comparison circuit includes: The input node is connected to the output of the gain unit; A voltage divider is connected between the input node and the reference potential node and is configured to provide an output voltage based on the voltage at the input node; and The comparator is configured to output first information or second information based on the result of a comparison between the output voltage from the voltage divider and the comparator reference voltage.

[0102] 9. The circuit according to embodiment 8, wherein the voltage divider includes a first resistor and a second resistor connected in series.

[0103] 10. A circuit according to any one of embodiments 7-9, wherein the reference potential node is connected to ground.

[0104] 11. A method for monitoring a power supply configured to provide a power supply voltage, and for monitoring a bandgap circuit configured to generate a substantially fixed reference voltage using the power supply voltage, the method comprising: Provides an output voltage equal to the smaller of the reference voltage multiplied by the gain value and the supply voltage; In response to the output voltage meeting the trigger value, first information indicating that the reference voltage meets the reference threshold and the power supply voltage meets the power supply threshold is provided; and In response to the output voltage failing to meet the trigger value, second information is provided indicating that the reference voltage fails to meet the reference threshold and / or the power supply voltage fails to meet the power supply threshold.

[0105] 12. The method according to embodiment 11, wherein the gain value depends on the power supply threshold and the reference threshold.

[0106] 13. The method according to Example 12, wherein the gain value is equal to the power supply threshold divided by the reference threshold.

[0107] 14. The method according to any one of Examples 11-13, wherein the power supply threshold is greater than a reference threshold.

Claims

1. A circuit for monitoring a power supply and for monitoring a bandgap circuit, the power supply being configured to provide a power supply voltage, and the bandgap circuit being configured to generate a substantially fixed reference voltage using the power supply voltage, the circuit comprising: A gain unit is configured to receive the reference voltage and the power supply voltage, and to provide an output voltage equal to the reference voltage multiplied by the smaller of the gain value and the power supply voltage; as well as The comparator circuit is configured as follows: In response to the output voltage meeting the trigger value, first information indicating that the reference voltage meets a reference threshold and the power supply voltage meets a power supply threshold is provided; and In response to the output voltage failing to meet the trigger value, second information is provided indicating that either the reference voltage fails to meet the reference threshold or the power supply voltage fails to meet the power supply threshold.

2. The circuit of claim 1, wherein the gain value depends on the power supply threshold and the reference threshold.

3. The circuit according to claim 2, wherein the gain value is equal to the power supply threshold divided by the reference threshold.

4. The circuit according to any one of claims 1-3, further comprising the bandgap circuit, the bandgap circuit being configured to generate the reference voltage substantially fixed using the power supply voltage.

5. The circuit according to any one of claims 1-4, wherein the power supply threshold is greater than the reference threshold.

6. The circuit according to any one of claims 1-5, wherein the comparison circuit comprises: An open-loop bandgap (OLBG) circuit is configured to receive the output voltage from the gain component and generate a first voltage and a second voltage, wherein the difference between the first voltage and the second voltage is based on the output voltage received from the gain component. as well as The comparator is configured to output either the first information or the second information based on the result of a comparison between the first voltage and the second voltage.

7. The circuit of claim 6, wherein the OLBG circuit comprises: The input node is connected to the output of the gain component; A first branch includes a first resistor and a second resistor connected in series between the input node and the reference potential node, and a diode connected in parallel with the second resistor of the first branch and between the reference potential node and the first output node, the first output node being provided between the first resistor and the second resistor of the first branch, the diode being configured to impede current flow between the reference potential node and the first output node, wherein a first voltage is provided on the first output node; The second branch includes a first resistor and a second resistor connected in series between the input node and the reference potential node, and a diode and a third resistor connected in series. The diode and the third resistor are connected in parallel with the second resistor of the second branch and between the reference potential node and the second output node, the second output node being provided between the first resistor and the second resistor of the second branch. The diode is configured to impede the current flow between the reference potential node and the second output node, wherein a second voltage is provided at the second output node.

8. The circuit according to any one of claims 1-5, wherein the comparison circuit comprises: The input node is connected to the output of the gain component; A voltage divider is connected between the input node and the reference potential node and is configured to provide an output voltage based on the voltage at the input node; as well as The comparator is configured to output either the first information or the second information based on the result of a comparison between the output voltage from the voltage divider and the comparator reference voltage.

9. The circuit of claim 8, wherein the voltage divider comprises a first resistor and a second resistor connected in series.

10. The circuit according to any one of claims 7-9, wherein the reference potential node is connected to ground.

11. A method for monitoring a power supply and a bandgap circuit, the power supply being configured to provide a power supply voltage, and the bandgap circuit being configured to generate a substantially fixed reference voltage using the power supply voltage, the method comprising: Provide an output voltage equal to the smaller of the reference voltage multiplied by the gain value and the supply voltage; In response to the output voltage meeting the trigger value, first information indicating that the reference voltage meets a reference threshold and the power supply voltage meets a power supply threshold is provided; as well as In response to the output voltage failing to meet the trigger value, second information is provided indicating that either the reference voltage fails to meet the reference threshold or the power supply voltage fails to meet the power supply threshold.

12. The method of claim 11, wherein the gain value depends on the power supply threshold and the reference threshold.

13. The method of claim 12, wherein the gain value is equal to the power supply threshold divided by the reference threshold.

14. The method according to any one of claims 11-13, wherein the power supply threshold is greater than the reference threshold.

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