Two stage detection to reduce voltage drop across critical battery voltage node

Abstract

The invention relates to a two-stage detection for reducing voltage drop on a critical battery voltage node. A power delivery system may include a power converter configured to be electrically coupled to a power source and further configured to supply electrical energy to one or more loads electrically coupled to an output of the power converter; and control circuitry configured to: determine whether a voltage node in the power delivery system has dropped below a warning threshold voltage; determining whether the voltage node has dropped below a critical threshold voltage, wherein the critical threshold voltage is less than the warning threshold voltage; in response to the voltage of the voltage node falling below the warning threshold voltage, reducing a maximum current drawn by the power converter from a first current level to a second current level; and in response to the voltage of the voltage node falling below the critical threshold voltage, reducing the maximum current drawn by the power converter from the second current level to a third current level.

Description

[0001] This application is a divisional application of the Chinese patent application with application number "202110865001.2", application date "July 29, 2021", and invention name "Dual-stage detection for reducing voltage drop at critical battery voltage nodes".

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This disclosure claims priority to U.S. Provisional Patent Application Serial No. 63 / 058,018, filed on July 29, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0004] The present disclosure relates generally to circuits for electronic devices, including but not limited to personal portable devices such as wireless telephones and media players, and more particularly to limiting current in power converters. Background Art

[0005] Portable electronic devices (including wireless telephones, such as mobile / cellular telephones, cordless telephones, mp3 players, and other consumer audio devices) are widely used. Such portable electronic devices may include circuitry for implementing a power converter that converts a battery voltage (e.g., provided by a lithium-ion battery) into a power supply voltage that is delivered to one or more components of the portable electronic device. The power delivery network may also regulate such a power supply voltage and isolate downstream loads of the one or more components from fluctuations in the output voltage of the battery during operation.

[0006] In addition to regulating the supply rail for the power supply voltage, it may be desirable for a power converter (or control circuitry for a power converter) to provide an active protection mechanism to limit the amount of current that may be drawn by one or more components powered from the supply rail. Summary of the invention

[0007] According to the teachings of the present disclosure, one or more disadvantages and problems associated with existing methods of operating power converters may be reduced or eliminated.

[0008] According to an embodiment of the present disclosure, a power delivery system may include: a power converter configured to be electrically coupled to a power source and further configured to supply electrical energy to one or more loads electrically coupled to an output terminal of the power converter; and a control circuit configured to: determine whether a voltage node in the power delivery system has dropped below a warning threshold voltage; determine whether the voltage node has dropped below a critical threshold voltage, wherein the critical threshold voltage is less than the warning threshold voltage; in response to the voltage of the voltage node dropping below the warning threshold voltage, reduce the maximum current drawn by the power converter from a first current level to a second current level; and in response to the voltage of the voltage node dropping below the critical threshold voltage, reduce the maximum current drawn by the power converter from the second current level to a third current level.

[0009] According to these and other embodiments of the present disclosure, a method can be used in a power delivery system having a power converter, the power converter being configured to be electrically coupled to a power source and also configured to supply electrical energy to one or more loads electrically coupled to an output of the power converter. The method can include: determining whether a voltage node in the power delivery system has dropped below a warning threshold voltage; determining whether the voltage node has dropped below a critical threshold voltage, wherein the critical threshold voltage is less than the warning threshold voltage; in response to the voltage of the voltage node dropping below the warning threshold voltage, reducing the maximum current drawn by the power converter from a first current level to a second current level; and in response to the voltage of the voltage node dropping below the critical threshold voltage, reducing the maximum current drawn by the power converter from the second current level to a third current level.

[0010] According to these and other embodiments of the present disclosure, a mobile device may include a power source, one or more loads, a power converter electrically coupled to the power source and further configured to supply power to the one or more loads, and a control circuit. The control circuit may be configured to: determine whether a voltage node in a power delivery system has dropped below a warning threshold voltage; determine whether the voltage node has dropped below a critical threshold voltage, wherein the critical threshold voltage is less than the warning threshold voltage; in response to the voltage of the voltage node dropping below the warning threshold voltage, reduce the maximum current drawn by the power converter from a first current level to a second current level; and in response to the voltage of the voltage node dropping below the critical threshold voltage, reduce the maximum current drawn by the power converter from the second current level to a third current level.

[0011] From the drawings, descriptions and claims included herein, the technical advantages of the present disclosure are obvious to those skilled in the art. The objects and advantages of the embodiments will be realized and achieved at least by the elements, features and combinations particularly pointed out in the claims.

[0012] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the claims set forth in the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] A more complete understanding of the present embodiments and their advantages may be obtained by referring to the following description in conjunction with the accompanying drawings, in which like reference numerals represent like features, and in which:

[0014] Figure 1 A block diagram illustrating selected components of an example power delivery network according to an embodiment of the present disclosure;

[0015] Figure 2 shows an example graph of an open circuit voltage of a battery and a state of charge of the battery according to an embodiment of the present disclosure;

[0016] Figure 3 A block diagram showing selected components of an equivalent circuit model of a battery according to an embodiment of the present disclosure;

[0017] Figure 4 shows example graphs of battery voltage and battery current and time associated with a current step drawn from a battery in accordance with an embodiment of the present disclosure;

[0018] Figure 5 An example first-order model of a battery simplified as a time-varying voltage source in series with an equivalent series resistance is shown according to an embodiment of the present disclosure;

[0019] Figure 6 shows an example graph of maximum battery current versus internal effective battery voltage for battery protection according to an embodiment of the present disclosure;

[0020] Figure 7 The embodiment according to the present disclosure is shown Figure 1 A block diagram of example selected impedances within a power delivery network is shown in;

[0021] Figure 8 shows an example graph of output power of a power converter versus battery current drawn by the power converter according to an embodiment of the present disclosure;

[0022] Fig. 9 shows an example graph of maximum battery current versus internal effective battery voltage for power converter stability according to an embodiment of the present disclosure;

[0023] Fig.10 shows an example graph of maximum battery current versus internal effective battery voltage for power limiting considerations according to an embodiment of the present disclosure;

[0024] Fig.11shows an example graph of maximum battery current versus internal effective battery voltage for current limiting considerations according to an embodiment of the present disclosure;

[0025] Fig.12 shows example graphs of battery voltage versus time, and maximum current drawn by a power converter versus time, according to an embodiment of the present disclosure;

[0026] Fig.13 An example block diagram showing selected components of a control circuit that may be used to implement a dual threshold protection mechanism according to an embodiment of the present disclosure;

[0027] Fig.14 shows example graphs of battery voltage versus time, and maximum current drawn by a power converter versus time, detailing fast attack and slow release control mechanisms according to embodiments of the present disclosure; and

[0028] Fig.15 It shows that the embodiment of the present disclosure can be used Fig.13 The state machine shown in the figure is implemented as a state diagram. DETAILED DESCRIPTION

[0029] Figure 1 A block diagram showing selected components of an example power delivery network 10 according to an embodiment of the present disclosure is shown. In some embodiments, the power delivery network 10 may be implemented within a portable electronic device, such as a smart phone, tablet computer, game controller, and / or other suitable device.

[0030] like Figure 1 As shown, the power delivery network 10 may include a battery 12 and a power converter 20, which is configured to convert a battery voltage V generated by the battery 12 into a power converter 20. CELL is converted into a power supply voltage V for powering multiple downstream components 18 SUPPLY , where each downstream component 18 can draw a corresponding current I from the output of the power converter 20 LOAD1 ,I LOAD2 ,I LOAD3 This means that the total load current I LOAD =I LOAD1 +I LOAD2 +…+I LOADNThe power converter 20 may be implemented using a boost converter, a buck converter, a buck-boost converter, a transformer, a charge pump, and / or any other suitable power converter. The downstream components 18 of the power delivery network 10 may include any suitable functional circuits or devices of the power delivery network 10, including but not limited to other power converters, processors, audio encoders / decoders, amplifiers, display devices, etc.

[0031] like Figure 1 As shown, the power delivery network 10 may also include a control circuit 30 for controlling the operation of the power converter 20, including the switching and commutation of switches within the power converter 20. In addition, as described in more detail below, the control circuit 30 may also implement a method for limiting the current I drawn from the battery 12. CELL Active protection mechanism.

[0032] It is generally known that lithium-ion batteries operate from 4.2V down to 3.0V, referred to as the open circuit voltage V of a battery (e.g., battery 12). OC As the battery discharges due to the current drawn from the battery, the battery's state of charge may also decrease, and the open circuit voltage V OC (which may be a function of the state of charge) may also be reduced due to electrochemical reactions occurring within the battery, such as Figure 2 As shown. At the open circuit voltage V OC Outside the 3.0V and 4.2V range, the capacity, life and safety of the lithium-ion battery may deteriorate. For example, at about 3.0V, about 95% of the energy in the lithium-ion battery cell may be consumed (that is, the state of charge is 5%), and if further discharge continues, the open circuit voltage V OC will tend to drop rapidly. Below about 2.4V, the metal plates of the lithium-ion battery may corrode, which may result in higher internal impedance, lower capacity, and potential short circuiting of the battery. Therefore, in order to protect the battery (e.g., battery 12) from excessive discharge, many portable electronic devices may prevent the battery from falling below a predetermined discharge end voltage V CELL-MIN operation.

[0033] Figure 3 1 shows a block diagram of selected components of an equivalent circuit model of a battery 12 according to an embodiment of the present disclosure. Figure 3 As shown, the battery 12 can be modeled as having a battery cell 32 having an open circuit voltage V OC , in series with a plurality of parallel resistor-capacitor sections 34 and also in series with an equivalent series resistor 36 of the battery 12, such equivalent series resistor 36 having a resistance of R0. N and their respective capacitors C1, C2, ..., C NCan simulate battery chemistry-related time constants τ1, τ2, ..., τ N , the time constant can be related to the open circuit voltage V OC and the equivalent series resistance 36 are lumped together. It is worth noting that Figure 3 The voltage V CELL-EFF The depicted electrical nodes capture the time-varying discharge behavior of the battery 12, and the battery voltage V CELL is the actual voltage seen at the output of the battery 12. The voltage V CELL-EFF may not be directly measured, and therefore the battery voltage V CELL may be the only voltage associated with the battery 12 that can be measured to assess the battery health state. It is also worth noting that at zero current draw (e.g., I CELL =0), the battery voltage V CELL Can be equal to the voltage V CELL-EFF , which can be equal to the open circuit voltage V at a given charging state OC .

[0034] Figure 4 shows the battery voltage V according to an embodiment of the present disclosure CELL and the battery current I CELL An example graph of current and time associated with a step in current drawn from the battery 12. Figure 4 As shown, in response to a current step event, as the battery voltage V CELL The response curve of experiences an initial transient drop (eg, due to the equivalent series resistance 36) and a transient drop due to the time constants τ1, τ2, ..., τ N The time-dependent voltage drop caused by the battery voltage V CELL Can respond to a step. The open circuit voltage V OC and various impedances R0, R1, R2, ..., R N may be a function of the state of charge of the battery 12, thus meaning that the transient response to a new, fully charged battery may be significantly different from the transient response to an aged, partially discharged battery.

[0035] In operation, control circuit 30 may determine the maximum battery current I that may be drawn from battery 12 at any given moment based on one or more constraints, including protection of battery 12, stability of power converter 20, and / or limitations associated with practical limitations. CELL .

[0036] The first constraint that may be imposed by the control circuit 30 is that the battery current I CELL The maximum value of the battery imposes a constraint. To illustrate the application of this constraint, Figure 5 An example first-order model of the battery 12 according to an embodiment of the present disclosure is shown, which is simplified to have a voltage VCELL-EFF , a time-varying voltage source 38 connected in series with an equivalent series resistor 36 having a resistance value of R0. The maximum battery current I that the battery 12 can deliver CELL-MAX can be directly dependent on the equivalent series resistance 36. The battery current I CELL The equivalent series resistor 36 must be passed through, which can reduce the battery voltage V CELL From the voltage V CELL-EFF The reduction is equal to the resistance R0 multiplied by the battery current I CELL The amount (for example, V CELL =V CELL-EFF -R0I CELL ). Perhaps more importantly, the battery current I flowing through the equivalent series resistor 36 CELL This may result in power dissipation within the battery 12, which is equal to the resistance R0 multiplied by the battery current I CELL The square of (for example, P = R0I CELL 2 ). At high discharge rates, the battery current I CELL This may result in significant heating within the battery 12. As discussed above, the battery voltage V CELL Must be kept above the discharge end voltage V CELL-MIN The requirement for the maximum battery current I CELL-MAX The limits are set as given below:

[0037]

[0038] Therefore, assuming only the battery imposes limitations, the maximum battery current I CELL-MAX It can be voltage V CELL-EFF function, and can be Figure 6 The line CON1 is drawn as shown.

[0039] To implement this limitation, the control circuit 30 may implement an active protection scheme to ensure that the end-of-discharge voltage V CELL-MIN will not be violated, thereby avoiding damage to the battery 12. For example, the control circuit 30 can be configured to monitor the battery voltage V at the terminals of the battery 12 CELL , and if Figure 6 The constraint CON1 shown in FIG. 1 changes the maximum battery current I drawn by the power converter 20 CELL-MAX , to ensure that the battery 12 is not over-discharged beyond its safe operating range, so as to extend the life of the battery 12. However, the maximum battery current I CELL-MAX This control is complicated by the fact that the transient response of the battery 12 can be multiple time constants (e.g., τ1, τ2, ..., τ N) as described above, and in a feed-forward manner measures this time constant for a given battery and varies the maximum battery current I CELL-MAX Therefore, as further described below, the control circuit 30 can implement a negative feedback control loop around the power converter 20, which can monitor the battery voltage V CELL And change the maximum battery current I CELL-MAX , to convert the battery voltage V CELL Maintain the desired target value.

[0040] In addition to limiting current to provide protection for battery 12 as described above, it may also be desirable to limit current to provide stability for power converter 20 so as to operate outside of the maximum power point into an unstable region of power converter 20, as described in more detail below. For illustration, reference is made to Figure 7 , which depicts an embodiment according to the present disclosure Figure 1 A detailed block diagram of the selected impedances within the power delivery network 10 is shown in FIG. Figure 7 As shown, the power delivery network 10 may utilize a current sensing resistor 54 in series with a trace resistor 52, an impedance 56 for modeling equivalent losses in the power converter 20, and a load 58 representing the sum of the downstream devices 18. Figure 5 Battery 12 is modeled as shown. Trace resistor 52 may have a resistance R representing the resistance of an electrical conduit (eg, connector, printed circuit board trace, etc.) between battery 12 and power converter 20. TRACE The sensing resistor 54 may have a resistance R SNS , and can be calculated based on the voltage drop across the sensing resistor 54 and the resistance R according to Ohm's law SNS To sense the battery current I CELL The impedance 56 can be realized by using a resistor R LOSS The losses within power converter 20 are modeled. After accounting for the power losses occurring in these different impedances, power converter 20 can deliver output power P to load 58. OUT , given as:

[0041] P OUT =I CELL V CELL-EFF -I C 2 ELL R TOT

[0042] in

[0043] R TOT =R0+R TRACE +R SNS+R LOSS

[0044] For a given total resistance R TOT And the given voltage V CELL-EFF , may exist as the battery current I CELL The output power P of the power delivery network 10 is a function of OUT The maximum power P MAX , which appears at the current I PMAX Where Figure 8 As shown, the current I PMAX It can be given by the following formula:

[0045]

[0046] Therefore, from Figure 8 As shown in CELL PMAX , the power delivery system 10 will operate with optimal power efficiency and stability, and when I CELL >I PMAX In the unstable region (output power P OUT Relative to the battery current I CELL The maximum allowable current I PMAX You can Fig. 9 The following is a plot of constraint CON2 superimposed on Figure 6 The maximum battery current I CELL-MAX The total resistance R TOT is greater than the equivalent series resistance R0, so it is obvious that the slope of constraint CON1 is steeper than that of constraint CON2. In the case of extrapolation, constraint CON2 line can intercept voltage V at 0V CELL-EFF The horizontal axis of Fig. 9 This is not shown in , as many batteries (e.g., lithium-ion batteries) will not be allowed to drop to such magnitudes.

[0047] For an efficient power converter, impedance 56 is negligible compared to equivalent series resistance 36, trace resistor 52, and sense resistor 54, making the total resistance R TOT can be rewritten as:

[0048] R TOT ≈R0+R TRACE +R SNS

[0049] As battery 12 discharges with use, equivalent series resistance 36 may increase, and voltage V CELL-EFF Therefore, corresponding to the maximum power P MAX The maximum allowable current I​PMAX It can be voltage V CELL-EFF and the impedance of the power delivery network 10 .

[0050] In addition to limiting current to provide protection for battery 12 as described above, and in addition to limiting current to provide stability for power converter 20 as described above, it may also or alternatively be desirable to limit current based on actual implementation considerations, as described in more detail below.

[0051] As an example, above a certain voltage V CELL-EFF In the case of CELL and hence the maximum power delivery capability P MAX may become so large that the design of power converter 20 becomes increasingly difficult or even infeasible. Practical limitations (such as the inductor saturation current and the required dynamic range of the current sensing circuit in power converter 20) may dictate the output power P OUT The power limit P LIM Thermal considerations may also need to be taken into account and may require limiting the maximum power delivery from the power converter 20 .

[0052] Assuming the output power P OUT Limited to power limit P LIM , the power balance equation of the power delivery system 10 can be written as:

[0053]

[0054] It can be rewritten as:

[0055]

[0056] This maximum allowable current I CELL-LIM You can Fig.10 The plot shown is for constraint CON3A superimposed on Fig. 9 The constraints described in CON1 and CON2 are on P MAX and P LIM The separation between the two power-limited regions is Fig.10 It is shown graphically in FIG as occurring at the breakpoint between the curves representing constraints CON2 and CON3A. LIM In the restricted area, the battery current I CELL The maximum value of can be set by the lower of the two values ​​of the maximum allowable current. Fig.10 As shown, along the curve of constraint CON3A, the battery current I CELL The maximum current may vary with the voltage V CELL-EFF Decrease and increase.

[0057] In addition to limiting current to provide protection for battery 12 as described above, limiting current to provide stability for power converter 20 as described above, and limiting current for power limitation considerations, it may also or alternatively be desirable to apply a fixed current limit I based on actual implementation considerations. FIXED , as described in more detail below. The maximum allowable current I FIXED You can Fig.11 The plot shown is for constraint CON3B superimposed on Fig.10 The constraints CON1, CON2, and CON3A depicted in FIG. Therefore, the battery current I CELL The maximum current can be set by the lowest of the four values ​​of the maximum allowable current.

[0058] In the above description, various active protection mechanisms protect the power converter 20 and its corresponding system modules (e.g., battery 12, downstream components 18, etc.), and each mechanism operates independently of each other. However, all mechanisms can work using a shared control parameter: the maximum battery current I CELL-MAX This shared control parameter may result from the fact that the current limit and active protection mechanisms of the power converter 20 must be dynamically updated during operation to account for the characteristics of the battery 12 (e.g., the open circuit voltage V OC , voltage V CELL-EFF , resistor R0), module-level considerations (e.g., resistor R TRACE ) and the efficiency of the power converter 20 (eg, by the resistor R LOSS In any given case, the maximum battery current I drawn from the battery 12 is CELL-MAX The maximum battery current I CELL-MAX Therefore, it may be advantageous to provide an active protection mechanism that can:

[0059] Dynamically track key system parameters (e.g., effective battery voltage V CELL_EFF , output power P OUT ), and adjust the maximum battery current I accordingly CELL-MAX ;

[0060] ·Regulate the maximum battery current I in a timely manner CELL-MAX ; and / or

[0061] At effective battery voltage V CELL_EFF Control is smoothly switched between each of the active protection mechanisms throughout the entire operating range.

[0062] Therefore, in order to obtain these advantages, when the battery voltage V CELLClose to the discharge end voltage V CELL-MIN When the battery protection of CON1 is constrained, it can include limiting the battery current I CELL This prevents the battery voltage V CELL Because the impedance of the battery 12 changes with its state of charge, this current limitation may need to be dynamic. Therefore, it is possible that when this protection scheme is activated, the power supply voltage V SUPPLY May fall below its target desired level.

[0063] One possible method is to set a voltage higher than the actual discharge end voltage V for the cutoff circuit. CELL-MIN Although this approach can protect the battery 12, it may not allow access to all of the energy that can be safely utilized in the battery 12. Another possible approach is to continuously monitor the battery voltage V using an analog-to-digital converter (ADC). CELL , and the battery voltage V CELL Drop to the discharge end voltage V CELL-MIN However, while potentially offering high accuracy, the approach using an ADC may require a significant amount of time for the conversion and may not be able to respond to fast transient loads. If a faster response time is desired, a high speed ADC may be used. However, such a high speed ADC may consume a significant amount of power and is not suitable for portable battery powered applications.

[0064] Another possible approach is to use a single comparator and a reactive loop that limits the current of the power converter 20 by actively throttling and thus limiting the maximum battery current I CELL-MAX To convert the battery voltage V CELL Maintain at about the end-of-discharge voltage V CELL-MIN This approach is disclosed in U.S. Patent No. 10,720,835 (hereinafter, the '835 patent), the entire contents of which are incorporated herein by reference. However, this single threshold approach may also have disadvantages. To illustrate, consider Figure 7 For the sensing voltage V SNS The capacitance C present at the electrical node SNS , and taking into account that this capacitance may vary between two capacitance values, for example due to aging of components of the power delivery network 10. For the same load step, with respect to the battery voltage V CELL The conversion rate of the battery voltage V CELL The comparator of this method can be set when V drops below a set threshold, and this setting of the comparator can initiate a reduction (attack) of the current limit of the power converter 20. However, in practice, the comparator delay and processing time are non-zero. During such a non-zero time interval, the battery voltage VCELL The drop in the sense voltage V SNS The conversion rate is proportional to the capacitance associated with the node. Therefore, for lower capacitance, the battery voltage V CELL The drop in voltage may be high, and the power converter 20 has no control over such a drop. This initial drop may be significant and may cause false alarms and unnecessarily trigger more stringent protection schemes (e.g., shutting down the system). Further, repeated voltage sags significantly below the comparator threshold may defeat the purpose of using such a protection scheme in the first place.

[0065] To overcome these disadvantages, the control circuit 30 can be further configured to implement two voltage thresholds of the power delivery network 10: based on the end-of-discharge voltage V CELL-MIN The critical threshold voltage and the warning threshold voltage V greater than the critical threshold voltage CELL-WARN The control circuit 30 can be configured to CELL drops below the warning threshold voltage V CELL-WARN When the current I drawn by the power converter 20 is G (If power converter 20 is the only load on battery 12, then I G =I CELL ) of the maximum power converter current I GMAX From the predicted maximum current level I GMAX_PREDICT Reduced to the first current level I GFILT +ΔI G ,like Fig.12 As shown. Value ΔI G According to the voltage difference ΔV = V CELL-WARN –V CELL-MIN and resistor R0 (for example, ΔI G =ΔV / R0). Therefore, when the warning threshold voltage V CELL-WARN When the discharge end voltage V CELL-MIN Before, higher than the discharge end voltage V CELL-MIN The amount of voltage margin is known and available. The value ΔI G May be stored as a programmable value and may be set based on factory characterization, in-situ characterization, and / or in any other suitable manner.

[0066] To avoid the delay associated with sensing current across sense resistor 54, control circuit 30 may generate a measured filtered current I GFILT , which simulates the current drawn from the battery 12 by the power converter 20 and supplied by the capacitor C SNS And the combined resistance R0+R TRACE +R SNSThe total average current of the filter is I G To perform this filtering, the control circuit 30 may be implemented as a circuit tuned to have a constant value greater than 1 / (R0+R TRACE +R SNS )C SNS Therefore, this calculation inherently takes into account the capacitance C SNS .

[0067] Further, if Fig.12 As shown, when the battery voltage V CELL drops below the discharge end voltage V CELL-MIN When the maximum battery current I CELL-MAX From the first current level I FILT +ΔI drops to equal (or approximately equal to) the measured filtered current I FILT In some embodiments, the second current level may be the measured filtered current I FILT Multiply by a gain factor greater than 1.

[0068] Fig.13 FIG. 4 is a block diagram showing selected components of a control circuit 30 that can be used to implement the dual threshold protection mechanism described above according to an embodiment of the present disclosure. Fig.13 As shown, the comparator 61 can convert the battery voltage V CELL With the warning threshold voltage V CELL-WARN The comparator 62 can compare the battery voltage V CELL and the discharge end voltage V CELL-MIN The outputs of comparators 61 and 62 may be received by a state machine 64, which may generate a maximum power converter current I based on the outputs of comparators 61 and 62. GMAX , as described in more detail below. The maximum power converter current I GMAX To control the switching of the switches inside the power converter 20 so as to limit the current drawn by the power converter 20 to such a maximum power converter current I GMAX .

[0069] Further, state machine 64 may be configured to provide a maximum power converter current I GMAX Different release rates are created. For example, once the load transient has passed, the state machine 64 can release (eg, increase) the maximum power converter current I GMAX , thus allowing the maximum power converter current I GMAX Returns to the predicted maximum current level I GMAX_PREDICTIn some embodiments, two release rates may be provided by state machine 64. One release rate may be the release rate described in the '835 patent. Once the battery voltage V CELL Increases again to the warning threshold voltage V CELL-WARN Above this, a second release rate may be imposed by state machine 64. This second release rate may allow for additional tuning and response time and current (and therefore, power) profile during recovery of power converter 20.

[0070] Fig.14 shows the battery voltage V according to an embodiment of the present disclosure CELL vs. time and the maximum power converter current I drawn by the power converter 20 GMAX An example graph of time details the fast attack and slow release control mechanism implemented by state machine 64. Further, Fig.15 An example state diagram is shown that may be implemented using the state machine 64 to implement a dual threshold, fast attack and slow release control mechanism with two different release rates in accordance with an embodiment of the present disclosure.

[0071] As used herein, when two or more elements are referred to as being “coupled” to each other, the term indicates that the two or more elements are in electrical or mechanical communication, as applicable, whether indirectly or directly, with or without intervening elements.

[0072] The present disclosure covers all changes, substitutions, changes, alterations and modifications to the example embodiments herein that will be understood by a person of ordinary skill in the art. Similarly, where appropriate, the appended claims cover all changes, substitutions, changes, alterations and modifications to the example embodiments herein that will be understood by a person of ordinary skill in the art. In addition, the reference to a device or system or a component of a device or system adapted to, arranged to, capable of, configured to, enabled to, enabled to operate or operable to perform a specific function in the appended claims covers the device, system or component, regardless of whether it or the specific function is activated, turned on or unlocked, as long as the device, system or component is so adapted, arranged, capable of, configured to, enabled to, enabled to operate or operable. Therefore, without departing from the scope of the present disclosure, the systems, devices and methods described herein may be modified, added or omitted. For example, the components of the systems and devices may be integrated or separated. Moreover, the operation of the systems and devices disclosed herein may be performed by more, less or other components, and the described methods may include more, less or other steps. Additionally, the steps may be performed in any suitable order. As used herein, "each" refers to every member of a set or every member of a subset of a set.

[0073] Although exemplary embodiments are shown in the drawings and described below, the principles of the present disclosure may be implemented using any number of techniques, whether currently known or not. The present disclosure should not be limited in any way to the exemplary implementations and techniques shown in the drawings and described above.

[0074] Unless specifically noted otherwise, items depicted in the drawings are not necessarily drawn to scale.

[0075] All examples and conditional language cited herein are for teaching purposes to help readers understand the disclosure and concepts contributed by the inventors to advance the art, and are interpreted as not being limited to these specifically cited examples and conditions. Although the embodiments of the present disclosure have been described in detail, it should be understood that various changes, substitutions and modifications may be made thereto without departing from the spirit and scope of the present disclosure.

[0076] Although specific advantages have been listed above, various embodiments may include some, none, or all of the listed advantages. Additionally, other technical advantages will become apparent to those of ordinary skill in the art after reading the foregoing drawings and descriptions.

[0077] To assist the Patent Office and any reader of any patent issuing in this application in interpreting the appended claims, Applicant wishes to note that unless the words "means for" or "step for" are expressly used in a particular claim, they are not intended to trigger 35 U.S.C. §112(f) in any of the appended claims or claim elements.

Claims

1. A power delivery system comprising: a power converter configured to be electrically coupled to a power source and further configured to supply electrical energy to one or more loads electrically coupled to an output of the power converter; as well as A control circuit, the control circuit being configured to: determining whether a voltage node in the power delivery system indicative of a terminal voltage of the power supply has dropped below a warning threshold voltage; determining whether the voltage node has dropped below a critical threshold voltage, wherein the critical threshold voltage is less than the warning threshold voltage; reducing a maximum current drawn by the power converter from a first current level to a second current level in response to the voltage at the voltage node dropping below the warning threshold voltage; and in response to the voltage of the voltage node falling below the critical threshold voltage, reducing the maximum current drawn by the power converter from the second current level to a third current level greater than zero, wherein the control circuit limits the maximum current drawn by the power converter by controlling a switch inside the power converter, The second current level is equal to the filtered current I generated by the control circuit. GFILT and a current ΔI determined based on a voltage difference between the warning threshold voltage and the critical threshold voltage and an equivalent series resistance R0 of the power supply. G The third current level is equal to the filtered current I GFILT The current level, Wherein, the filtered current I GFILT Simulates the current drawn from the power source by the power converter by capacitor C SNS And the combined resistance R0+R TRACE +R SNS The total average current of the filter, capacitor C SNS represents the capacitance at the voltage node, R TRACE represents the resistance of the electrical conduit between the power source and the power converter, R SNS represents the resistance of the sense resistor used to sense the supply current, and The control circuit implements a dual-threshold release control mechanism for the maximum current drawn by the power converter, in which the control circuit increases the maximum current drawn by the power converter at a first release rate when the voltage of the voltage node increases to above the warning threshold voltage, and increases the maximum current drawn by the power converter at a second rate when the voltage of the voltage node increases to above the critical threshold voltage.

2. The power delivery system of claim 1 , wherein the control circuit is further configured to reduce the maximum current drawn by the power converter after the voltage at the voltage node has dropped below the critical threshold voltage until the voltage at the voltage node rises above the critical threshold voltage.

3. A power delivery system according to claim 2, wherein the control circuit is further configured to increase the maximum current drawn by the power converter after the voltage at the voltage node has dropped below the critical threshold voltage and increased again to above the critical threshold voltage until the voltage at the voltage node drops below the critical threshold voltage again.

4. The power delivery system of claim 3, wherein the control circuit is further configured to repeat the steps of decreasing the maximum current drawn and increasing the maximum current drawn to maintain the operation of the power delivery system in a steady state.

5. A power delivery system according to claim 2, wherein the control circuit is further configured to increase the maximum current drawn by the power converter after the voltage at the voltage node has dropped below the critical threshold voltage and increased again to above the critical threshold voltage until the voltage at the voltage node drops below the critical threshold voltage again or the maximum current drawn returns to the first voltage level.

6. The power delivery system of claim 1, wherein the power delivery system further comprises a battery, the power converter draws current from the battery, and the critical threshold voltage is based on an end-of-discharge voltage of the battery.

7. The power delivery system of claim 6, wherein the voltage at the voltage node measures a terminal voltage of the battery.

8. A method, comprising performing the following steps in a power delivery system having a power converter and a control circuit, the power converter being configured to be electrically coupled to a power source and further configured to supply electrical energy to one or more loads electrically coupled to an output of the power converter, the steps comprising: determining whether a voltage node in the power delivery system indicative of a terminal voltage of the power supply has dropped below a warning threshold voltage; determining whether the voltage node has dropped below a critical threshold voltage, wherein the critical threshold voltage is less than the warning threshold voltage; reducing a maximum current drawn by the power converter from a first current level to a second current level in response to the voltage at the voltage node dropping below the warning threshold voltage; and in response to the voltage of the voltage node falling below the critical threshold voltage, reducing the maximum current drawn by the power converter from the second current level to a third current level greater than zero, wherein the control circuit limits the maximum current drawn by the power converter by controlling a switch inside the power converter, The second current level is equal to the filtered current I generated by the control circuit. GFILT and a current ΔI determined based on a voltage difference between the warning threshold voltage and the critical threshold voltage and an equivalent series resistance R0 of the power supply. G The third current level is equal to the filtered current I GFILT The current level, Wherein, the filtered current I GFILT Simulates the current drawn from the power source by the power converter by capacitor C SNS And the combined resistance R0+R TRACE +R SNS The total average current of the filter, capacitor C SNS represents the capacitance at the voltage node, R TRACE represents the resistance of the electrical conduit between the power source and the power converter, R SNS represents the resistance of the sense resistor used to sense the supply current, and The control circuit implements a dual-threshold release control mechanism for the maximum current drawn by the power converter, in which the control circuit increases the maximum current drawn by the power converter at a first release rate when the voltage of the voltage node increases to above the warning threshold voltage, and increases the maximum current drawn by the power converter at a second rate when the voltage of the voltage node increases to above the critical threshold voltage.

9. The method of claim 8 further comprising reducing the maximum current drawn by the power converter after the voltage at the voltage node has dropped below the critical threshold voltage until the voltage at the voltage node rises above the critical threshold voltage.

10. The method according to claim 9 further includes increasing the maximum current drawn by the power converter after the voltage of the voltage node has dropped below the critical threshold voltage and increased again to above the critical threshold voltage until the voltage of the voltage node drops below the critical threshold voltage again.

11. The method of claim 10, repeating the steps of decreasing the maximum current drawn and increasing the maximum current drawn to maintain operation of the power delivery system in a steady state.

12. The method according to claim 9 also includes, after the voltage of the voltage node has dropped below the critical threshold voltage and increased again to be above the critical threshold voltage, increasing the maximum current drawn by the power converter until the voltage of the voltage node drops below the critical threshold voltage again, or the maximum current drawn returns to the first voltage level.

13. The method of claim 8, wherein the power delivery system further comprises a battery, the power converter draws current from the battery, and the critical threshold voltage is based on an end-of-discharge voltage of the battery. The method of claim 13 , wherein the voltage at the voltage node measures a terminal voltage of the battery.

15. A mobile device, comprising: power supply; one or more loads; a power converter electrically coupled to the power source and further configured to supply electrical energy to the one or more loads; as well as A control circuit, the control circuit being configured to: determining whether a voltage node in the power delivery system indicative of a terminal voltage of the power supply has dropped below a warning threshold voltage; determining whether the voltage node has dropped below a critical threshold voltage, wherein the critical threshold voltage is less than the warning threshold voltage; reducing a maximum current drawn by the power converter from a first current level to a second current level in response to the voltage at the voltage node dropping below the warning threshold voltage; and in response to the voltage of the voltage node falling below the critical threshold voltage, reducing the maximum current drawn by the power converter from the second current level to a third current level greater than zero, wherein the control circuit limits the maximum current drawn by the power converter by controlling a switch inside the power converter, The second current level is equal to the filtered current I generated by the control circuit. GFILT and a current ΔI determined based on a voltage difference between the warning threshold voltage and the critical threshold voltage and an equivalent series resistance R0 of the power supply. G The third current level is equal to the filtered current I GFILT The current level, Wherein, the filtered current I GFILT Simulates the current drawn from the power source by the power converter by capacitor C SNS And the combined resistance R0+R TRACE +R SNS The total average current of the filter, capacitor C SNS represents the capacitance at the voltage node, R TRACE represents the resistance of the electrical conduit between the power source and the power converter, R SNS represents the resistance of the sense resistor used to sense the supply current, and The control circuit implements a dual-threshold release control mechanism for the maximum current drawn by the power converter, in which the control circuit increases the maximum current drawn by the power converter at a first release rate when the voltage of the voltage node increases to above the warning threshold voltage, and increases the maximum current drawn by the power converter at a second rate when the voltage of the voltage node increases to above the critical threshold voltage.

16. The mobile device of claim 15, wherein the control circuit is further configured to reduce the maximum current drawn by the power converter after the voltage at the voltage node has dropped below the critical threshold voltage until the voltage at the voltage node rises above the critical threshold voltage.

17. A mobile device according to claim 16, wherein the control circuit is further configured to increase the maximum current drawn by the power converter after the voltage at the voltage node has dropped below the critical threshold voltage and increased again to above the critical threshold voltage until the voltage at the voltage node drops below the critical threshold voltage again.

18. The mobile device of claim 17, wherein the control circuit is further configured to repeat the steps of decreasing the maximum current drawn and increasing the maximum current drawn to maintain the operation of the power delivery system in a steady state.

19. A mobile device according to claim 15, wherein the control circuit is further configured to increase the maximum current drawn by the power converter after the voltage of the voltage node has dropped below the critical threshold voltage and increased again to above the critical threshold voltage until the voltage of the voltage node drops below the critical threshold voltage again or the maximum current drawn returns to the first voltage level.

20. The mobile device of claim 15, further comprising a battery, the power converter drawing current from the battery, and wherein the critical threshold voltage is based on an end-of-discharge voltage of the battery.

21. The mobile device of claim 20, wherein the voltage at the voltage node measures a terminal voltage of the battery.

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