POWER SUPPLY MONITORING

Abstract

The disclosed concepts provide a circuit and a method for monitoring a power supply and a bandgap circuit. 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. The circuit includes a gain component configured to receive the reference voltage and the supply voltage and to provide an output voltage equal to the lesser of the reference voltage multiplied by a gain value and the supply voltage. Additionally, the circuit includes a comparator circuit configured to provide initial information indicating that the reference voltage meets a reference threshold and that the supply voltage meets a supply threshold.The comparator circuit is configured to provide secondary information indicating that either the reference voltage does not meet the reference threshold and / or the supply voltage does not meet the supply threshold, in response to the output voltage not meeting the trigger value.

Description

TECHNICAL AREA

[0001] The present disclosure relates generally to the monitoring of a power supply and in particular to the monitoring of a power supply and a bandgap circuit. BACKGROUND

[0002] For many systems, it is crucial to ensure that a power supply provides a voltage that meets a required minimum threshold to guarantee proper and safe system operation. This can be particularly challenging for single-supply systems, as the circuits used to monitor the power supply are often themselves powered by the supply. Consequently, under certain conditions, the monitoring circuits may not provide a reliable indication of the power supply's status.

[0003] For example, the supply voltage provided by the power supply may need to reach a certain threshold. To ensure this, the supply voltage can be compared to a reference voltage. While it may be possible to generate the reference voltage under a wide range of power supply operating conditions, it typically cannot be guaranteed in all cases. In fact, the circuit generating the reference voltage may require a minimum supply voltage, the circuit itself may be faulty, or the circuit may need time to start up properly and provide a stable output. Of course, the reference voltage itself can be subject to monitoring circuitry, but this increases costs and suffers from the same problems as the monitoring circuitry used for the power supply.

[0004] Publication US 2015 / 0168969A1 describes a device comprising an input for providing a first voltage signal; a level shifter connected to the input to convert the first voltage signal into a second input voltage, the second input voltage having a voltage level higher than the voltage level of the first voltage signal; and an open-loop reference core coupled to the level shifter. The open-loop reference core receives the second input voltage and generates an output signal indicating whether the first voltage signal is above or below a reference level.

[0005] Publication JP 2015 - 11 505 A describes a reference voltage generation unit for generating a constant reference voltage when the power supply voltage is higher than a predetermined threshold voltage. A detection result is output by recognizing whether the power supply voltage is higher than a prescribed voltage based on the reference voltage, specifically when a voltage exceeding the threshold voltage by a predetermined potential is detected.

[0006] Publication US 2001 / 0010478A1 shows a circuit with a first transistor whose current path lies between a supply terminal and a first output terminal. A second transistor has a current path coupled between the first output terminal and a reference terminal. The current path of the second transistor has essentially the same width and length as the current path of the first transistor. A first comparator circuit has a first and a second input terminal and a second output terminal. The first input terminal is connected to the first output terminal. The first comparator circuit generates a control signal depending on a voltage between the first and second input terminals. A generator circuit receives the control signal and generates an output voltage at the supply terminal.

[0007] Accordingly, there is a need for improved means of reliably monitoring a power supply. SUMMARY

[0008] According to one aspect, a circuit is provided for monitoring a power supply and a bandgap circuit. The power supply is configured to provide a supply voltage. The bandgap circuit is configured to generate an essentially fixed reference voltage using the supply voltage.

[0009] The circuit includes a gain component configured to receive the reference voltage and the supply voltage and to provide an output voltage equal to the lesser of the reference voltage multiplied by a gain value and the supply voltage. Additionally, the circuit includes a comparator circuit configured to provide initial information indicating that the reference voltage meets a reference threshold and that the supply voltage meets a supply threshold, in response to the output voltage meeting a trigger value. The comparator circuit is configured to provide secondary information indicating that either the reference voltage does not meet the reference threshold and / or the supply voltage does not meet the supply threshold, in response to the output voltage not meeting the trigger value.

[0010] According to another aspect of the present disclosure, a method for monitoring a power supply and a bandgap circuit is provided. The power supply is configured to provide a supply voltage, and the bandgap circuit is configured to generate a substantially fixed reference voltage using the supply voltage.

[0011] The method involves providing an output voltage equal to the lesser of the reference voltage multiplied by a gain value and the supply voltage. In response to the output voltage meeting a trigger value, the method provides initial 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 secondary information indicating that either the reference voltage fails to meet the reference threshold and / or the supply voltage fails to meet the supply threshold.

[0012] The expert will recognize additional features and advantages upon reading the following detailed description and upon examining the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The invention will now be described by way of example with reference to the accompanying drawings, in which: Fig. 1 represents a state-of-the-art circuit for monitoring a power supply and a bandgap circuit; Fig. 2 represents a circuit for monitoring a power supply and a bandgap circuit according to one embodiment; Fig. 3 an example of how to respond to the circuit of Fig. 2 during a fast start-up of the power supply or a slow start-up of the bandgap circuit; Fig. 4 an example of how to respond to the circuit of Fig. 2 represents during a slow start-up of the power supply; Fig. 5 represents a circuit for monitoring a power supply and a bandgap circuit according to a further embodiment; Fig. 6. A circuit diagram of an open-loop bandgap (OLBG) circuit according to one aspect of embodiments; and Fig. Figure 7 shows a flowchart of a procedure for monitoring a power supply and a bandgap circuit.

[0014] It should be noted that these figures are drawn schematically and not to scale. For the sake of clarity and practicality, the relative dimensions and proportions of parts of these figures have been exaggerated or reduced in size in the drawings. DETAILED DESCRIPTION

[0015] The following description presents exemplary aspects of the present revelation. However, it should be understood that such a description is not intended to limit the scope of the present revelation. Rather, the description also includes combinations and modifications of the exemplary aspects described herein.

[0016] The disclosed concepts relate to monitoring a power supply and a bandgap circuit powered by the power supply. In particular, embodiments relate to monitoring a magnitude of the supply voltage generated by the power supply and a magnitude of the substantially fixed reference voltage generated by the bandgap circuit. For this purpose, an output voltage is generated equal to the lesser of the reference voltage multiplied by a gain value and the supply voltage. If the output voltage is equal to or greater than a trigger value, then it is determined that both (i) the reference voltage meets a reference threshold and (ii) the supply voltage meets a supply threshold.Alternatively, if the output voltage is less than the trigger value, then it is determined that either (or both) (i) the reference voltage does not meet the reference threshold and (ii) the supply voltage does not meet the supply threshold.

[0017] In other words, if the smallest reference voltage multiplied by the gain and the supply voltage fails to meet a trigger value, then it is inferred that at least one of the reference voltages and the supply voltage is falling below its predefined thresholds. This therefore provides a simple way to determine whether at least one of the power supply and the bandgap circuit is not generating an adequate voltage (e.g., due to damage, a fault, unusual operating conditions, etc.). This information can then be used to decide whether to start a system powered by the power supply to inform a user or system to perform further diagnostics, or to inform a system or user to resolve a problem.

[0018] To clarify, a bandgap circuit is a voltage reference circuit that generates a nearly constant voltage using the supply voltage. This means that regardless of potential fluctuations in the power supply, electrical load, temperature, etc., the bandgap circuit can generate a nearly constant voltage. Accordingly, a bandgap circuit can be used to determine whether a power supply provides a voltage that meets a threshold (e.g., by comparing the reference voltage generated by the bandgap circuit with the supply voltage).

[0019] However, the reference voltage may be incorrect when the bandgap circuit starts up (i.e., it may be unstable for a period of time after the bandgap circuit is initially powered on). Furthermore, if the supply voltage is excessively low, the reference voltage may be unstable. If the bandgap circuit is damaged, for example, by excessive heating, overcurrent, or excessive force, it may also output an unexpected reference voltage. Thus, there are several circumstances under which the bandgap circuit may generate an unexpected reference voltage. Therefore, there is a chance that monitoring the supply voltage based on the reference voltage will be inaccurate. In other words, monitoring based on the reference voltage generated by a bandgap circuit may be unreliable.

[0020] Accordingly, the proposed embodiments combine the comparison of the supply voltage and the reference voltage with a trigger level. If either the reference voltage scaled by a gain value or the supply voltage does not meet the trigger level, then it can be deduced that one of the supply voltages or the reference voltage does not meet its respective threshold values.

[0021] This disclosure therefore provides a circuit for monitoring a power supply configured to provide a supply voltage. The power supply can be any electrical device configured to supply electrical power to an electrical load. The power supply provides a supply voltage that ideally has a magnitude within a predetermined range, although this may be subject to the connected load and other operating conditions of the power supply. The supply voltage can provide a DC voltage that is substantially stable over time (i.e., non-alternating).

[0022] The circuit also monitors a bandgap circuit configured to generate a substantially constant reference voltage using the supply voltage. That is, the bandgap circuit produces a nearly constant voltage, with only minor variations due to changes in the power supply, electrical load, or temperature. The power supply is used to drive the bandgap circuit, and due to the nature of the bandgap circuit, the generated reference voltage is nearly constant regardless of the power supplied by the power supply. Nevertheless, the reference voltage may deviate from an expected value due to startup fluctuations, insufficient power supplied by the power supply, and / or damage to the bandgap circuit.

[0023] To perform monitoring, the circuit includes an amplification component configured to receive the reference voltage and the supply voltage and to provide an output voltage equal to the lesser of (i) the reference voltage multiplied by a gain value and (ii) the supply voltage.

[0024] Accordingly, the amplification component receives the reference voltage and scales it by the gain value. It can then compare the scaled reference voltage with the supply voltage to determine which of the scaled reference voltage and the supply voltage is smaller. Based on this comparison, the amplification component provides, generates, or otherwise outputs a voltage equal to the smaller of the scaled reference voltage and the supply voltage.

[0025] The circuit also includes a comparator circuit that receives the output voltage from the gain component. The comparator circuit compares the output voltage with a trigger value and, based on the comparison, provides initial or secondary information (e.g., it outputs either a high-state voltage or a low-state voltage).

[0026] When the output voltage meets or exceeds the trigger value, the comparator circuit provides initial information. That is, if any value of the output voltage is greater than or equal to the trigger value, the comparator circuit outputs initial information. This initial information indicates that the reference voltage meets a reference threshold and that the supply voltage meets a supply threshold.

[0027] If the output voltage does not meet the trigger threshold, the comparator circuit provides additional information. Specifically, if any value of the output voltage is lower than the trigger threshold, the comparator circuit outputs further information. This additional information indicates that either the reference voltage does not meet the reference threshold and / or the supply voltage does not meet the supply threshold.

[0028] In some embodiments, the first piece of information can be provided as a high-state signal, and the second piece of information can be provided as a low-state signal. For example, the comparator circuit can output a voltage corresponding to a "1" as the first piece of information and a voltage corresponding to a "0" as the second piece of information. That is, the comparator circuit can pull an output node into a high state if it is determined that the output voltage meets a trigger value, or it can pull the output node into a low state if it is determined that the output voltage does not meet a trigger value. Of course, the opposite of the above can also be true (i.e., the first piece of information can be provided as a low-state signal, and the second piece of information can be provided as a high-state signal).

[0029] The supply threshold can be a desired minimum supply voltage. This can be a minimum voltage required to reliably, safely, and / or predictably supply power to a load that draws power from the power supply.

[0030] The reference threshold can be a desired minimum reference voltage. This value can be set to be the minimum voltage expected to be output by the bandgap circuit when operating under expected conditions. That is, this value can be the minimum voltage expected to be output by the bandgap circuit, provided that the bandgap circuit is operating in a stable state (i.e., not during startup) with an adequate power supply and is not damaged.

[0031] In typical embodiments, the supply threshold is higher than the reference threshold. In one case, the supply threshold can be between 1.44 V and 1.62 V, and the reference threshold can be between 1.05 V and 1.15 V.

[0032] In some embodiments, the gain value (used to scale the reference voltage) can depend on the supply threshold and the reference threshold. That is, the gain value can be set based on the supply threshold and the reference threshold. Specifically, the gain value can be equal to the supply threshold divided by the reference threshold. In this case, the trip value can be equal to the supply threshold.

[0033] In a specific embodiment, the comparator circuit can include an open-loop bandgap (OLBG) circuit and a comparator.

[0034] The OLBG circuit can be configured to receive the output voltage from the amplifying component and to generate a first voltage and a second voltage, where the difference between the first and second voltages is based on the received output voltage from the amplifying component. That is, the OLBG can be configured to output two voltages whose difference depends on the magnitude of the output voltage.

[0035] The comparator can be configured to output either the first or the second set of information based on the result of a comparison between the first and second voltages. In other words, if the difference between the first and second voltages meets (or exceeds) a certain condition, the first set of information can be output. Alternatively, if the difference between the first and second voltages does not meet the certain condition, the second set of information can be provided.

[0036] This combination of the OLBG circuit and the comparator circuit allows the determination of whether the output voltage from the gain component meets the trigger threshold without requiring an externally generated reference voltage. In fact, these components are configured to provide initial information when the output voltage meets or exceeds the trigger threshold, and subsequent information when the output voltage does not meet the trigger threshold. This is primarily facilitated by the OLBG circuit, which generates two voltages whose difference is based on the output voltage from the gain component.

[0037] In other words, since the OLBG circuit requires neither an external reference voltage nor a supply voltage (other than the output voltage from the amplification component), this comparator circuit can reliably provide first or second information regardless of the supply voltage condition.

[0038] To be more specific, the OLBG circuit can have an input node that is connected to the output of the amplification component.

[0039] The OLBG circuit can include a first branch comprising a first resistor and a second resistor connected in series between the input node and a reference potential node (e.g., ground), and a diode connected in parallel with the second resistor of the first branch and between the reference potential node and a first output node. The first output node can be located between the first and second resistors of the first branch, and the diode can be configured to block current flow between the reference potential node and the first output node. The first voltage can be applied to the second output node.

[0040] The OLBG circuit can 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. Alternatively, the second branch can include a diode and a third resistor connected in series, with the diode and the third resistor connected in parallel to the second resistor of the second branch and between the reference potential node and a second output node. The second output node can be located between the first and second resistors of the second branch. The diode can be configured to block current flow between the reference potential node and the second output node. In this case, the second voltage can be applied to the second output node.

[0041] Of course, other configurations and modifications of the OLBG circuit can be implemented by the expert, and additional components can be provided in the OLBG circuit.

[0042] While the comparator circuit that includes the OLBG circuit and the comparator is desirable, other configurations of the comparator circuit are provided.

[0043] For example, the comparator circuit can include a voltage divider and a comparator. Specifically, the comparator circuit can have an input node connected to the output of the 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 can be configured to provide an output voltage based on the voltage across the input node. The comparator can be 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 a comparator reference voltage.

[0044] Naturally, this comparator circuit requires a comparator reference voltage, which can be generated from another source. Nevertheless, it is understood that this comparator circuit still provides a means of monitoring both the supply voltage from the power supply and the reference voltage from the bandgap circuit using a single comparator circuit (which, for example, does not require additional components for monitoring the power supply and the bandgap circuit). In fact, the voltage divider provides a means of reducing the output voltage from the gain component in such a way that a reliable assessment of the operation of the power supply and the bandgap circuit can still be made under low-voltage conditions.

[0045] In summary, the present disclosure provides a means for monitoring a supply voltage of a power supply and a reference voltage from a bandgap circuit (which should be essentially constant regardless of voltage fluctuations of the power supply and temperature conditions) using a simple circuit. In particular, by using the gain component, which provides an output voltage equal to the lesser of (i) the reference voltage multiplied by a gain value and (ii) the supply voltage, a single comparator circuit can be provided that evaluates the output voltage from the gain component to assess whether the power supply and the bandgap circuit are operating as expected.

[0046] To best understand the advantages of the disclosed embodiments, it is helpful to understand how power supplies are currently monitored. One such system is in Fig. 1 shown.

[0047] As shown, there is a power supply 10 that is configured to provide a supply voltage V Supp Power supply 10 can be used to supply power to another system. Power supply 10 is connected to a bandgap circuit 20. As described above, the bandgap circuit 20 is a voltage reference circuit that provides a nearly constant reference voltage V. Ref using the supply voltage V Supp generated.

[0048] To monitor the magnitude of the supply voltage. V Supp A supply monitoring unit 30 is provided. The supply monitoring unit 30 receives V Supp from the power supply 10 and V Reffrom the bandgap circuit 20. By comparing V Supp and V Ref can be determined whether V Supp Minimum requirements are met. If not, the supply monitoring system 30 indicates that the supply is low.

[0049] A power-on reset circuit 50 can also be provided. The power-on reset circuit 50 ensures that V Supp provides a high level of supply. This means that supply monitoring 30 indicates whether V Supp a minimum supply level is met, and the power-on reset circuit 50 indicates whether V Supp provides a high supply. If both conditions are met, then power supply 10 provides a suitable supply voltage.

[0050] However, problems can occur if the bandgap circuit 20 does not have an exact V RefThis may be due to damage to the bandgap circuit 20 or may be related to the power supply 10. For example, during the commissioning of the power supply 10, it may take time for the bandgap circuit 20 to stabilize and provide a stable and accurate V. Ref provides. In some cases, the voltage provided by power supply 10 can be used for a stable and accurate generation of V. Ref insufficient. In these cases, the provided monitoring system cannot provide a correct indication of whether the power supply 10 has a sufficient voltage. Supp provides.

[0051] Therefore, a bandgap OK circuit 40 can be provided. This circuit can V Ref monitor and provide an indication of whether V RefIt is accurate and stable. However, it is understood that this requires additional space, more components and costs, and can itself be prone to errors.

[0052] A solution according to the proposed embodiments is in Fig. 2 shown. That is, Fig. Figure 2 represents a circuit for monitoring a power supply 10 and a bandgap circuit 20 according to one embodiment. This circuit can provide an indication of whether the power supply 10 and the bandgap circuit 20 are providing the expected voltages or not.

[0053] As shown, the circuit includes a gain component 110 and a comparator circuit 120. The gain component 110 receives the supply voltage V. Supp and the reference voltage V Refand provides an output voltage g(V) to the comparator circuit 120. The comparator circuit 120 receives g(V) and provides either first or second information.

[0054] The amplification component 110 is configured to provide g(V) equal to the smaller of the V Ref multiplied by an amplification value A and V Supp is. For this purpose, the amplification component 110 can first the V Ref scale by the gain value. Then the gain component 110 can be the scaled V. Ref with V Supp compare and output the smaller of the two voltages.

[0055] The comparator circuit 120 is configured to provide initial information indicating that V when g(V) meets a trigger value. Ref a reference threshold Vtrig _ref fulfilled and that V Supp a supply threshold Vtrig _suppfulfilled. Alternatively, in response to g(V) not fulfilling a trigger value, the comparator circuit 120 is configured to provide secondary information indicating that V Ref a reference threshold Vtrig _ref not fulfilled and / or that V Supp a supply threshold Vtrig _supp not fulfilled. Accordingly, the output from the comparison circuit 120 shows whether the bandgap circuit 20 and the power supply 10 are working as expected.

[0056] In other words, the amplification component 110 can be configured to perform the following: if A*VRed <VSupp,dann gilt g(V)=A*VRef Otherwise, g(V)=VRef where A=Vtrig_supp / Vtrig_ref

[0057] The comparator circuit 120 then compares g(V) with a trigger value. If g(V) meets or exceeds the trigger value, the comparator circuit 120 can output initial information (e.g., it can output a high value). If g(V) does not meet the trigger value, the comparator circuit 120 can output secondary information (e.g., it can output a low value). The trigger value can be equal to Vtrig. _supp be.

[0058] To demonstrate the operation of this circuit, Fig. Figure 3 shows an exemplary response of the circuit during a rapid start-up of the power supply 10. Similarly, this can be demonstrated in Fig. The three responses shown apply equally to a scenario in which the bandgap circuit 20 is slowly put into operation.

[0059] As shown, the power supply starts at 10 and V SuppIt rises rapidly before stabilizing at an expected level. The V output by the bandgap circuit 20 Ref However, the output remains at 0, either because the power supply 10 was quickly started and stabilized, or because the bandgap circuit 20 needs some time to become operational.

[0060] Accordingly, g(V) remains at 0 because it is equal to the lower of V. Ref * A (i.e. 0) or V Supp Consequently, the output from comparator circuit 120 also remains low (which indicates second piece of information). It should be noted that in other monitoring circuits, it may be indicated that the circuit is operating normally when V Supp V Ref exceeds the limit, even though the band gap switching 20 has not yet been started.

[0061] After some time, the bandgap circuit 20 and V starts. Refg(V) begins to rise. Accordingly, g(V) also begins to rise. Finally, g(V) reaches a trigger value. When this occurs, the output of the comparator circuit switches to high (indicating initial information).

[0062] After operation for a period of time, the bandgap circuit 20 is damaged and V Ref The value begins to decrease. As soon as g(V) falls below the trigger value, the output of the comparator circuit switches to low (indicating secondary information). It should be noted that in other monitoring circuits, it may be indicated that the circuit operates normally until V Supp finally decreases (i.e., the power supply 10 switches off) when V Supp V Ref exceeds the limit, even though the band gap circuit 20 was damaged.

[0063] Another example demonstrating the operation of the circuit is in Fig. 4 shown. In this case, the power supply 10 is slowly brought into operation and begins to provide a sufficient V. Supp to provide.

[0064] As shown, the power supply starts at 10 and V Supp It rises slowly. Because of this slow rise, V increases. Ref also essentially at the same time. Accordingly, g(V) equals V. Supp , if V Ref * A greater than V Supp is.

[0065] After a certain period of time, V reaches Ref its expected initial value. g(V) continues to increase when V Supp smaller than V Ref * A remains. It should be noted that in other monitoring circuits it may be specified that the circuit is operating normally when V Supp V Ref exceeds, although V Supp not yet Vtrig _supp has achieved.

[0066] Finally, g(V) (still equal to V) reaches supp) the trigger value. At this point, the output of the comparator circuit switches to high (indicating initial information). g(V) continues to rise for a short period if V Supp still smaller than A * V Ref is. Finally, g(V) oscillates at A * V Ref a.

[0067] After some time, the power supply is switched off. Supp begins to decrease, while V Ref remains stable, as does g(V). Finally, V Supp smaller than A * V Ref , and g(V) falls below the trigger level. At this point, the output of the comparator circuit switches to low (indicating initial information).

[0068] As demonstrated by these scenarios, the monitoring circuit provides a reliable way to indicate when both the power supply 10 and the bandgap circuit 20 are operating as expected, and when at least one of them is not.

[0069] Fig. Figure 5 represents a circuit for monitoring a power supply 10 and a bandgap circuit 20 according to a further embodiment. This circuit operates essentially like the circuit of Fig. 2. A repeated description of the amplification component 110 is therefore omitted for the sake of brevity. However, the comparator circuit 120 is implemented in this case in the form of an OLBG circuit 130 and a comparator 140.

[0070] The OLBG circuit 130 is configured to receive g(V) from the amplifying component 110 and to generate a first voltage and a second voltage. The difference in magnitude between the generated first and second voltages is based on g(V). Accordingly, the difference between these voltages provides a means of assessing the magnitude of g(V) without requiring an external reference voltage.

[0071] Comparator 140 is configured to output either the first or second information based on the result of a comparison between the first and second voltages. That is, comparator 140 assesses the difference between the first and second voltages from the OLBG circuit 130 and outputs either first or second information depending on this difference. For example, if the difference exceeds a certain value, first information can be provided, and if the difference does not exceed a certain value, second information can be provided (or vice versa).

[0072] Fig. Figure 6 shows a circuit diagram of an OLBG circuit 130, which is used in the circuit of Fig. 5 can be implemented.

[0073] As shown, the OLBG circuit 130 has an input node 131 connected to the output of the gain component 110. The input node 131 therefore receives g(V). The OLBG circuit 130 has a first branch for supplying the first voltage V1 to a first output node 132 and a second branch for supplying the second voltage V2 to a second output node 133.

[0074] The first branch has 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 and between ground and a first output node 132. The first output node 132 is located 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 positioned to block current flow between ground and the first output node 132.

[0075] The second branch comprises 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 between ground and a second output node 133 and in parallel with the second resistor 135b. The second output node 133 is located between the first and second resistors 135b of the second branch. The diode 136b is positioned to block current flow between ground and the second output node 133 (via the third resistor 137).

[0076] The resistance of the first resistor 134a of the first branch and the first resistor 134b of the second branch can be equal. The resistance of the second resistor 135a of the first branch and the second resistor 135b of the second branch can be equal. A circuit trip point of the OLBG circuit 130 can be defined as occurring when the first voltage and the second voltage are equal. That is, if the voltage at the 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 resistance of the first resistors 134a and 134b and the resistance of the third resistor 137.

[0077] Accordingly, these resistors can be selected such that the difference between the first voltage and the second voltage is negative when g(V) is less than a trigger value, and positive when g(V) is equal to or greater than the trigger value (or vice versa). The comparator 140 can be configured accordingly to provide suitable first or second information.

[0078] Fig. Figure 7 presents a flowchart of a procedure for monitoring a power supply and a bandgap circuit. 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.

[0079] In step 210, an output voltage is provided that is equal to the smaller of the reference voltage from the bandgap circuit multiplied by a gain value and the supply voltage. For this purpose, a subset of the multiplication / scaling of the reference voltage by the gain value can be provided before comparing the scaled reference voltage and the supply voltage to determine the smaller of the two.

[0080] The gain value can depend on a supply threshold (which specifies a desired minimum supply voltage) and a reference threshold (which specifies a desired minimum threshold voltage). Specifically, the gain value can be equal to the supply threshold divided by the reference threshold. The supply threshold can also be greater than the reference threshold.

[0081] Step 220 determines whether the output voltage provided in step 210 meets a trigger threshold. That is, it determines whether the output voltage is greater than or equal to the trigger threshold. If so, the procedure proceeds to step 230. If not, the procedure proceeds to step 240.

[0082] In step 230, initial information is provided / output. This initial information indicates that the reference voltage meets a reference threshold and the supply voltage meets a supply threshold. In other words, this initial information indicates that both the power supply and the bandgap circuit are operating as expected.

[0083] In step 240, a second piece of information is provided / output. This second piece of information indicates that either the reference voltage does not meet the reference threshold and / or the supply voltage does not meet the supply threshold. This means that at least one (or both) of the power supply and the bandgap circuit are providing an unexpected voltage.

[0084] Steps 210-240 can be repeated iteratively if the supply voltage and the reference voltage change. This allows the supply voltage and the threshold voltage to be continuously monitored to ensure they meet requirements.

[0085] Although specific examples have been illustrated and described here, the person skilled in the art will recognize that a multitude of alternative and / or equivalent implementations can replace the specific examples shown and described without deviating from the scope of this disclosure. This application is intended to cover any adaptations or variations of the specific examples discussed herein. Therefore, it is intended that this disclosure is limited only by the claims and their equivalents.

[0086] It should be noted that the methods and devices, including their preferred embodiments, as set forth in this document, may be used alone or in combination with the other methods and devices disclosed herein. Furthermore, the features set forth in connection with a device are also applicable to a corresponding method and vice versa. Moreover, all aspects of the methods and devices set forth in this document may be combined in any way. In particular, the features of the claims may be combined with one another in any manner.

[0087] It should be noted that the description and drawings merely illustrate the principles of the proposed methods and systems. A person skilled in the art will be able to implement various arrangements which, although not explicitly described or shown here, embody the principles of the invention and are included in its meaning and scope of protection. Furthermore, all examples and embodiments set forth in this document are expressly intended only for illustrative purposes, to assist the reader in understanding the principles of the proposed methods and systems. Moreover, all statements herein that provide principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass equivalents thereof.

[0088] The following embodiments are disclosed: 1. Circuit for monitoring a power supply configured to provide a supply voltage and for monitoring a bandgap circuit configured to generate a substantially fixed reference voltage using the supply voltage, wherein the circuit comprises: an amplification component configured to receive the reference voltage and the supply voltage and to provide an output voltage equal to the lesser of the reference voltage multiplied by a gain value and the supply voltage; and a comparison circuit configured to: in response to the output voltage meeting a trigger value, to provide initial information indicating that the reference voltage meets a reference threshold and the supply voltage meets a supply threshold; and In response to the fact that the output voltage does not meet the trigger value, a second piece of information is provided indicating that either the reference voltage does not meet the reference threshold and / or the supply voltage does not meet the supply threshold. 2. Circuit according to embodiment 1, wherein the gain value depends on the supply threshold and the reference threshold. 3. Circuit according to embodiment 2, wherein the gain value is equal to the supply threshold value divided by the reference threshold value. 4. Circuit according to one of embodiments 1-3, further comprising the bandgap circuit configured to generate the substantially fixed reference voltage using the supply voltage. 5. Circuit according to one of embodiments 1-4, wherein the supply threshold is greater than the reference threshold. 6. Circuit according to one of embodiments 1-5, wherein the comparison circuit comprises: an open-loop bandgap (OLBG) circuit configured to receive the output voltage from the gain component and to generate a first voltage and a second voltage, the difference between the first voltage and the second voltage being based on the received output voltage from the gain component; and a comparator 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. Circuit according to embodiment 6, wherein the OLBG circuit comprises: an input node that is connected to the output of the amplification component; a first branch comprising a first resistor and a second resistor connected in series between the input node and a reference potential node, and a diode connected in parallel to the second resistor of the first branch and between the reference potential node and a first output node, wherein the first output node is provided between the first and second resistors of the first branch, wherein the diode is configured to block current flow between the reference potential node and the first output node, and wherein the first voltage is provided at the first output node; a second branch comprising 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, wherein the diode and the third resistor are connected in parallel to the second resistor of the second branch and between the reference potential node and a second output node, wherein the second output node is provided between the first and second resistors of the second branch, wherein the diode is configured to block the current flow between the reference potential node and the second output node, and wherein the second voltage is provided at the second output node. 8. Circuit according to one of embodiments 1-5, wherein the comparison circuit comprises: an input node that is connected to the output of the amplification component; a voltage divider connected between the input node and a reference potential node, configured to provide an output voltage based on the voltage at the input node; and a comparator 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 a comparator reference voltage. 9. Circuit according to embodiment 8, wherein the voltage divider comprises a first resistor and a second resistor connected in series. 10. Circuit according to one of embodiments 7-9, wherein the reference potential node is connected to ground. 11. Method for monitoring a power supply configured to provide a supply voltage and for monitoring a bandgap circuit configured to generate a substantially fixed reference voltage using the supply voltage, the method comprising: Providing an output voltage equal to the smaller of the reference voltage multiplied by a gain value and the supply voltage; In response to the output voltage meeting a trigger value, providing initial information indicating that the reference voltage meets a reference threshold and the supply voltage meets a supply threshold; and In response to the output voltage not meeting the trigger value, providing second information indicating that either the reference voltage does not meet the reference threshold and / or the supply voltage does not meet the supply threshold. 12. Method according to embodiment 11, wherein the amplification value depends on the supply threshold and the reference threshold. 13. Method according to embodiment 12, wherein the amplification value is equal to the supply threshold value divided by the reference threshold value. 14. Method according to one of embodiments 11-13, wherein the supply threshold is greater than the reference threshold.

Claims

[1] Circuit for monitoring a power supply configured to provide a supply voltage and for monitoring a bandgap circuit configured to generate a substantially fixed reference voltage using the supply voltage, the circuit comprising: an amplification component configured to receive the reference voltage and the supply voltage and to provide an output voltage equal to the lesser of the reference voltage multiplied by a gain value and the supply voltage; and a comparison circuit configured to: in response to the output voltage meeting a trigger value, to provide initial information indicating that the reference voltage meets a reference threshold and the supply voltage meets a supply threshold; and In response to the fact that the output voltage does not meet the trigger value, a second piece of information is provided indicating that either the reference voltage does not meet the reference threshold and / or the supply voltage does not meet the supply threshold. [2] Circuit according to claim 1, wherein the gain value depends on the supply threshold and the reference threshold. [3] Circuit according to claim 2, wherein the gain value is equal to the supply threshold divided by the reference threshold. [4] Circuit according to any one of claims 1-3, further comprising the bandgap circuit configured to generate the substantially fixed reference voltage using the supply voltage. [5] Circuit according to one of claims 1-4, wherein the supply threshold is greater than the reference threshold. [6] Circuit according to any one of claims 1-5, wherein the comparison circuit comprises: an open-loop bandgap (OLBG) circuit configured to receive the output voltage from the gain component and to generate a first voltage and a second voltage, the difference between the first voltage and the second voltage being based on the received output voltage from the gain component; and a comparator 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] Circuit according to claim 6, wherein the OLBG circuit comprises: an input node that is connected to the output of the amplification component; a first branch comprising a first resistor and a second resistor connected in series between the input node and a reference potential node, and a diode connected in parallel to the second resistor of the first branch and between the reference potential node and a first output node, wherein the first output node is provided between the first and second resistors of the first branch, wherein the diode is configured to block the current flow between the reference potential node and the first output node, and wherein the first voltage is provided at the first output node; a second branch comprising 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, wherein the diode and the third resistor are connected in parallel to the second resistor of the second branch and between the reference potential node and a second output node, wherein the second output node is provided between the first and second resistors of the second branch, wherein the diode is configured to block the current flow between the reference potential node and the second output node, and wherein the second voltage is provided at the second output node. [8] Circuit according to any one of claims 1-5, wherein the comparison circuit comprises: an input node that is connected to the output of the amplification component; a voltage divider connected between the input node and a reference potential node, configured to provide an output voltage based on the voltage at the input node; and a comparator 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 a comparator reference voltage. [9] Circuit according to claim 8, wherein the voltage divider comprises a first resistor and a second resistor connected in series. [10] Circuit according to one of claims 7-9, wherein the reference potential node is connected to ground. [11] Method for monitoring a power supply configured to provide a supply voltage and for monitoring a bandgap circuit configured to generate a substantially fixed reference voltage using the supply voltage, the method comprising: Providing an output voltage equal to the lesser of the reference voltage multiplied by a gain value and the supply voltage; in response to the output voltage meeting a trigger value, providing initial information indicating that the reference voltage meets a reference threshold and the supply voltage meets a supply threshold; and In response to the output voltage not meeting the trigger value, a second piece of information is provided indicating that either the reference voltage does not meet the reference threshold and / or the supply voltage does not meet the supply threshold. [12] Method according to claim 11, wherein the amplification value depends on the supply threshold and the reference threshold. [13] Method according to claim 12, wherein the amplification value is equal to the supply threshold divided by the reference threshold. [14] Method according to one of claims 11-13, wherein the supply threshold is greater than the reference threshold.

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