Control circuit and method for controlling a dc / dc converter

Abstract

A control circuit for controlling a power converter is provided. The control circuit is configured to operate the power converter in a PFM mode using a set of activated PFM functional blocks while a set of PWM functional blocks used to operate the power converter in a PWM mode are not activated. Further, the control circuit is configured to enter a switching state in which the power converter operates in the PFM mode and one or more PWM functional blocks of the set of PWM functional blocks are activated when a transition from operating the power converter in the PFM mode to operating the power converter in the PWM mode is prepared.

Description

Technical Field

[0001] The present disclosure relates to a control circuit and a corresponding method for controlling a DC / DC converter. Background Art

[0002] A DC / DC converter can be run in different operating modes to optimize the efficiency of the converter over a wide range of input voltages and / or output load currents. Figure 1a As shown, pulse frequency modulation (PFM) generally has a higher operating efficiency 101 for a relatively low load current 102, while continuous conduction modulation (CCM) generally has a higher operating efficiency 101 for a relatively high load current 102. Optimal operating efficiency 101 may be achieved by operating the power converter in PFM mode when the load current 102 is at or below a predetermined load current threshold, and operating the power converter in CCM mode when the load current 102 is above the predetermined load current threshold.

[0003] It should be noted that discontinuous conduction modulation (DCM) and continuous conduction modulation (CCM) are examples of pulse width modulation (PWM). The aspects outlined in the context of CCM operation are generally applicable to PWM operation.

[0004] Figure 1b The operation of the power converter in PFM mode is shown for a relatively low load current 102. This allows the power switches of the power converter to operate at a relatively low switching frequency 103, thereby enabling the power converter to operate efficiently. In PFM mode, regulation of the power converter output voltage can be achieved by varying the switching frequency 103.

[0005] As the load current 102 increases, the switching frequency 103 increases (up to a maximum frequency 109, which may also be referred to as a PWM frequency), ultimately triggering a mode transition from PFM mode to CCM mode (i.e., PWM mode). In PWM mode, output voltage regulation can be achieved by increasing the duty cycle of one or more power switches of the power converter through pulse width modulation.

[0006] The mode transition from PFM mode to PWM mode and the corresponding conversion of the regulation scheme from PFM to PWM may affect the stability of the power converter output voltage regulation. The present disclosure addresses the technical problem of performing an efficient mode transition from PFM mode to PWM mode to ensure stable regulation of the power converter output voltage. Summary of the Invention

[0007] According to one aspect, a control circuit for controlling a power converter is described. The control circuit is configured to operate the power converter in a pulse frequency modulation (PFM) mode using a set of activated PFM function blocks (of the control circuit) while a set of PWM function blocks (of the control circuit) for operating the power converter in a pulse width modulation (PWM) mode is inactivated. Furthermore, the control circuit is configured to, when preparing to switch from operating the power converter in the PFM mode to operating the power converter in the PWM mode, enter a switching state in which the power converter operates in the PFM mode and in which one or more PWM function blocks in the set of PWM function blocks are activated (while one or more other PWM function blocks in the set of PWM function blocks remain inactivated).

[0008] According to another aspect, a method for controlling a power converter is described. The method includes operating the power converter in a PFM mode using a set of activated PFM function blocks while a set of PWM function blocks for operating the power converter in a PWM mode is inactivated. Furthermore, the method includes, in preparation for switching from operating the power converter in the PFM mode to operating the power converter in the PWM mode, entering a switching state in which the power converter operates in the PFM mode and in which one or more PWM function blocks in the set of PWM function blocks are activated.

[0009] It should be noted that the methods and systems outlined in this disclosure (including preferred embodiments thereof) can be used alone or in combination with other methods and systems disclosed herein. Furthermore, features outlined in the context of a system also apply to the corresponding method. Furthermore, all aspects of the methods and systems outlined in this disclosure may be combined in any manner. In particular, features of the claims may be combined with each other in any manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The present invention is explained below in an exemplary manner with reference to the accompanying drawings, in which:

[0011] Figure 1a shows the operating efficiency of the power converter in different operating modes;

[0012] Figure 1b shows the mode transition from PFM mode to CCM (i.e. PWM mode);

[0013] Figure 1c shows the level of the output voltage during mode transition from PFM mode to CCM (i.e., PWM) mode;

[0014] Figure 2 A converter system comprising a power converter and a control circuit for controlling the power converter is shown;

[0015] Figure 3a The generation of turn-on trigger and turn-off trigger for controlling the high-side switch of the power converter in PFM mode is shown;

[0016] Figure 3b shows the generation of turn-on trigger and turn-off trigger in CCM (ie PWM) mode; and

[0017] Figure 4 A flow chart illustrating an example method for controlling a power converter is shown. DETAILED DESCRIPTION

[0018] As described above, the present disclosure relates to providing stable regulation of the output voltage of a DC / DC power converter during a mode transition from PFM mode to CCM mode (i.e., PWM mode). When sudden dynamic changes in the load force the power converter to switch modes quickly, the quality of the output voltage regulation may be significantly affected.

[0019] Figure 1c An example PFM-CCM transition is shown which is triggered by a so-called emergency comparator, which detects that the output voltage 125 (which is regulated to a given target voltage 126 ) is below a predetermined emergency threshold 127 .

[0020] One of the advantages of PFM operation is that it uses a relatively simple control scheme. Therefore, when the power converter is operating in PFM mode, many functional blocks of the power converter control circuit (which are used to operate the power converter in CCM mode) can be inactive. As a result, overall power consumption can be reduced.

[0021] During the transition from PFM mode to CCM mode, all functional blocks required for CCM mode are enabled and / or activated. However, since these functional blocks were deactivated in PFM mode, CCM mode starts operating with unbiased regulation. Therefore, the PFM-CCM transition can cause a significant drop in the output voltage 125 (down to Figure 1c level 128 shown) because the regulation loop needs to first achieve the output load current switching between PFM mode and CCM mode and then needs to reverse the output voltage drop.

[0022] Figure 1c A transition from PFM mode 112 to CCM mode 111 is shown, which is caused by a sudden increase in load current 123 (which is above a predetermined transition threshold 124, which is used to perform a planned transition from PFM mode 112 to CCM mode 111). The sudden increase in load current 123 causes the output voltage 125 to drop, thereby triggering the emergency comparator (represented by emergency pulse 121), resulting in an immediate transition to CCM mode 111.

[0023] Figure 1c It also illustrates how a sudden drop in load current 123 within CCM mode 111 causes regulation to enter a dormant state (represented by pulse 122 ).

[0024] like Figure 1c As shown, a sudden transition from PFM mode 112 (with relatively high voltage ripple) to CCM mode 111 (operating with a fixed clock) can cause a significant drop in output voltage 125. Furthermore, emergency threshold 127 is typically set to a safe voltage below the loop DC inaccuracy plus ripple, so that the emergency comparator is not triggered during normal operation. Consequently, the emergency comparator can be triggered relatively late (thus further affecting output voltage 125).

[0025] Figure 2 A block diagram of an example converter system 200 is shown, which includes power converters 210, 220, in particular a buck converter 210 and a boost converter 220 connected via an inductor 201, each converter 210, 220 including a driver circuit 211, 212, 213, 221, 222, 223. The system 200 also includes a control circuit 230, wherein the control circuit 230 includes:

[0026] One or more PFM function blocks 232 , 253 , which are applicable only to PFM mode 112 ;

[0027] One or more PWM function blocks 253, 254, 256, 257, 258, 259, 260, which are applicable only to PWM (particularly CCM) mode 111; and

[0028] One or more common function blocks 234 , 233 , 235 , 236 , 240 , 241 , 251 may be commonly used in the PFM mode 112 and the PWM mode 111 .

[0029] Figure 3a 1 shows the variation of the inductor current 301 (flowing through the inductor 201) and the output voltage 125 over time in the PFM mode 112. The control circuit 230 is configured to repeatedly generate:

[0030] a turn-on trigger 304 for turning on one or more high-side switches of power converters 210 , 220 (and turning off one or more low-side switches of power converters 210 , 220 ); and

[0031] A turn-off trigger 306 for turning off one or more high-side switches of the power converters 210 , 220 (and turning on one or more low-side switches of the power converters 210 , 220 ).

[0032] In the PFM mode 112, the output voltage 125 can be compared to a predetermined voltage threshold 302 (which is typically lower than the target voltage 126, 252 of the output voltage 125 and / or higher than the emergency threshold 127). When the output voltage 125 reaches and / or falls below the predetermined voltage threshold 302 (which can be detected by the PFM function block 253), a turn-on trigger 304 can be generated.

[0033] Once one or more high-side switches of power converters 210, 220 are turned on, the inductor current 301 increases. The inductor current 301 can be compared with a predetermined (fixed) current threshold 305 (within the PFM functional block 232). When the inductor current 301 reaches the predetermined current threshold 305, a shutdown trigger 306 can be generated.

[0034] Once one or more high-side switches of power converters 210 , 220 are turned off, inductor current 301 decreases and eventually drops to zero at time 307 . This causes output voltage 125 to drop, ultimately resulting in a subsequent turn-on trigger 304 .

[0035] The increase in load current 123 causes the output voltage 125 to drop faster, which in turn causes the subsequent turn-on trigger 304 to be generated faster, i.e., thereby increasing the switching frequency 103 of the one or more high-side switches of the power converters 210, 220. Eventually, the time gap 308 between the moment 307 when the inductor current 301 drops to zero and the subsequent turn-on trigger 304 drops to zero, so that the maximum switching frequency 109 of the PFM mode 112 (which may be equal to the PWM frequency) is reached.

[0036] Figure 3b 1 shows the relationship between inductor current 301 and time in PWM mode 111. In PWM mode 111, a turn-on trigger 304 is generated using a fixed clock signal (which is provided by PWM function block 257, possibly in conjunction with PWM function blocks 258 and 259). A turn-off trigger 306 is generated by comparing inductor current 301 to an adaptive peak current threshold 315. The comparison can be performed within PWM function block 256. When inductor current 301 reaches the adaptive peak current threshold 315, a turn-off trigger 306 can be generated.

[0037] The adaptive peak current threshold 315 may depend on an error voltage that indicates a deviation between the output voltage 125 and a target voltage 126, 252 (eg, provided by the digital-to-analog converter 251). The error voltage may be generated by the PWM function blocks 253, 254.

[0038] Additional functional blocks of the control circuit 230 may be:

[0039] PWM function block 255 for generating a ramp signal (which is typically used to generate a shutdown trigger 306);

[0040] PWM function block 260, used to detect sleep requirements (used to put the PWM regulator into sleep);

[0041] ● Common function block 241, for short-circuit protection;

[0042] One or more common function blocks 235, 236 for zero-crossing detection;

[0043] Common function block 234 for generating a shutdown trigger 306;

[0044] Common function block 233 for generating a conduction trigger 304; and / or

[0045] Common function block 240, used for logic operations.

[0046] The control circuit 230 can be configured to operate in a switching state to prepare for the transition from the PFM mode 112 to the PWM mode 111. In the switching state, the power converters 210, 220 operate in the PFM mode 112 such that the PFM functional blocks and the common functional blocks are active. In addition, a subset of the PWM functional blocks can be activated to pre-bias the subsequent PWM-based regulation. In particular,

[0047] When the power converters 210 , 220 begin operating in the PWM mode 111 , one or more PWM function blocks 253 , 254 for generating an error voltage may be activated to ensure that the adaptive peak current threshold 315 is at the correct level; and / or

[0048] When the power converters 210 , 220 begin operating in the PWM mode 111 , the PWM function block 256 for comparing the inductor current 301 with the adaptive peak current threshold 315 may be activated to ensure that the comparator is in a stable state.

[0049] On the other hand, one or more other PWM functional blocks may remain inactive during the switching state, e.g.

[0050] A PWM function block 255 for generating a ramp signal;

[0051] PWM function block 260 for detecting sleep requirements; and / or

[0052] • One or more functional blocks 257, 258, 259 for generating a clock signal.

[0053] The control circuit 230, such as the logic block 240, can be configured to detect whether a switching condition for entering the switching state is satisfied. In response to this, the control circuit 230 can enter the switching state while maintaining operation of the power converters 210, 220 in the PFM mode 112. The actual transition to the PWM mode 111 can be triggered by the following conditions:

[0054] The switching frequency 103 reaches the maximum frequency 109;

[0055] The load current 123 exceeds the load current threshold 124: and / or

[0056] Trigger the emergency comparator.

[0057] Since the control circuit 230 is already prepared for the PWM mode 111 in the switching state, the drop of the output voltage 125 can be significantly reduced.

[0058] An example condition for entering the switching state may be that the switching frequency 103 reaches a predetermined switching frequency 105 (eg, Figure 1b ). Thus, a switching state 108 may be provided for switching the frequency 103 between the switching frequency 105 and the maximum frequency 109.

[0059] Thus, control of the multi-mode power converters 210, 220 is described, whereby the latency of transitioning between PFM and PWM control is reduced. Specifically, one or more functional blocks required for the PWM mode 111 can be pre-biased in anticipation of the PFM-to-PWM transition while still operating in the PFM mode 112.

[0060] In other words, in addition to PFM and PWM modes, a third operating mode is described. This third operating mode is a switching state 108 for transitioning from PFM to PWM operation (i.e., from a relatively low to a relatively high load current 102). Switching state 108 enables converters 210, 220 to operate in the PFM operating mode while pre-biasing one or more functional blocks required for operation in the PWM operating mode. Switching state 108 can be initiated once the PFM mode load current capability is about to reach its maximum value and converter DC voltage regulation has not yet been lost.

[0061] Once one or more PWM function blocks are enabled, the one or more PWM function blocks operate in parallel with the PFM operation of the converters 210 and 220. As long as the PFM mode 112 is able to support the output load current 102, the control outputs of the one or more PWM function blocks are ignored. Once the PFM mode 112 reaches its maximum output load capability and the output load continues to increase, DC regulation is violated and the output voltage 125 begins to drop. The drop in output voltage 125 causes the controller error signal to increase (i.e., the error voltage increases), which causes the PWM function block to reverse the output voltage drop by regulating to an increased peak current (i.e., an increased adaptive peak current threshold 315).

[0062] The actual transition from PFM operation to PWM operation during the switching state 108 can occur at a point in time when one or more PWM functional blocks are adjusted to a peak current 315 that is higher than the current 305 provided by the PFM operation. Thus, the output of one or more PWM functional blocks is no longer ignored but is used for the actual transition. Thus, a smooth transition between PFM mode and PWM mode can be achieved.

[0063] One or more input factors may be used as conditions for initiating the switching state 108. Example input factors are: PFM operating frequency 103, number of PFM pulses before an idle period, input voltage, and / or output current. The conditions for entering the switching state 108 may be defined based on one or more of these input factors.

[0064] The control circuit 230 can be configured to anticipate a transition to PWM mode 111 when the switching frequency 103 approaches the PWM switching frequency 109. When the PFM switching frequency 103 exceeds a predetermined PWM sub-block pre-bias threshold 105, one or more PWM functional blocks can be pre-biased (in a switching state 108) in preparation for the transition from PFM to PWM. This reduces control delays when the transition actually occurs, thereby reducing discontinuities in the output voltage 125.

[0065] Given that the output load current 102 is relatively high when transitioning from PFM to PWM, activation of one or more PWM functional blocks does not significantly impact the efficiency of the power converters 210 , 220 .

[0066] As described above, when operating the power converters 210, 220 in the switching state 108, the actual mode transition from the PFM mode 112 to the PWM mode 111 may occur automatically once the adaptive peak current threshold 315 (used within the PWM mode 111) reaches and / or exceeds the current threshold 305 (used within the PFM mode 112).

[0067] Figure 4A flow chart of a method 400 (possibly computer-implemented) for controlling power converters 210, 220 (particularly switch-mode power converters 210, 220, such as buck converters, boost converters, or buck-boost converters) is shown. The method 400 includes operating 401 the power converters 210, 220 in a PFM mode 112 using a set of activated PFM function blocks 231, 232, while a set of PWM function blocks 253, 254, 255, 256, 257, 258, 259, 260 for operating the power converters 210, 220 in a pulse width modulation (PWM) mode 111 is inactivated. Thus, energy-efficient operation of the power converters 210, 220 (at relatively low load currents 102) is achieved.

[0068] Method 400 further includes, in preparation for transitioning from operating power converters 210, 220 in PFM mode 112 to operating power converters 210, 220 in PWM mode 111, entering 402 a switching state 108, in which power converters 210, 220 are still operating in PFM mode 112 (and not yet in PWM mode 111). However, one or more PWM function blocks 253, 254, 256 (particularly a subset) of the group of PWM function blocks 253, 254, 255, 256, 257, 258, 259, 260 are activated within switching state 108 (regardless of the signals generated by the one or more activated PWM function blocks 253, 254, 256 for performing actual operation of power converters 210, 220 (particularly for performing actual regulation of output voltage 124 of power converters 210, 220)). Thus, an energy-efficient, stable, and smooth transition to PWM mode 111 can be performed.

[0069] Thus, a control circuit 230 for controlling power converters 210, 220 (particularly switch-mode power converters 210, 220) is described. The control circuit 230 is configured to operate the power converters 210, 220 in PFM mode 112 using a set of activated PFM function blocks 231, 232, while a set of PWM function blocks 253, 254, 255, 256, 257, 258, 259, 260 for operating the power converters 210, 220 in PWM mode 111 (particularly CCM or DCM mode) are inactive. As a result, the power consumption of the set of PWM function blocks 253, 254, 255, 256, 257, 258, 259, 260 can be reduced (possibly to zero).

[0070] When operating the power converters 210 , 220 in the PWM mode 111 , the set of PFM function blocks 231 , 232 may be deactivated, while the set of PWM function blocks 253 , 254 , 255 , 256 , 257 , 258 , 259 , 260 may be activated.

[0071] The control circuit 230 is further configured to, in preparation for transitioning from operating the power converters 210, 220 in the PFM mode 112 to operating the power converters 210, 220 in the PWM mode 111, enter a switching state 108 in which the power converters 210, 220 continue to operate in the PFM mode 112. However, one or more PWM function blocks 253, 254, 256 (particularly a subset) of the set of PWM function blocks 253, 254, 255, 256, 257, 258, 259, 260 may be activated within the switching state 108 to prepare for a smooth transition to the PWM mode 111.

[0072] The one or more PWM function blocks 253, 254, 256 activated in the switching state 108 can be configured to determine a deviation of the output voltage 125 of the power converter 210, 220 from the target voltage 126, 252. In particular, the one or more PWM function blocks 253, 254, 256 can be configured to determine an error voltage. Alternatively, or in addition, the one or more PWM function blocks 253, 254, 256 activated in the switching state 108 can be configured to determine an adaptive peak current threshold 315 for generating a trigger 306 (in particular, a turn-off trigger) for opening or closing (in particular, turning off) the (high-side) power switch of the power converter 210, 220. The adaptive peak current threshold 315 can depend on the deviation of the output voltage 125 of the power converter 210, 220 from the target voltage 252 (in particular, the adaptive peak current threshold 315 can depend on the error voltage).

[0073] Alternatively, or in addition, one or more PWM function blocks 253 , 254 , 256 activated in the switching state 108 may be configured to compare the inductor current 301 through the inductor 201 of the power converter 210 , 220 with a (adaptive) peak current threshold 315 to generate a trigger 306 for turning on or off the power switch of the power converter 210 , 220 .

[0074] By activating one or more of the above-mentioned PWM function blocks 253 , 254 , 256 , a particularly smooth transition to the PWM mode 111 can be achieved.

[0075] The control circuit 230 may be configured to keep one or more PWM function blocks 255, 257, 258, 259, 260 of the set of PWM function blocks 253, 254, 255, 256, 257, 258, 259, 260 inactive during the switching state 108. The one or more PWM function blocks 255, 257, 258, 259, 260 that remain inactive during the switching state 108 may include:

[0076] One or more PWM function blocks 257, 258, 259 for generating clock signals;

[0077] One or more PWM function blocks 255 for generating a ramp signal; and / or

[0078] • One or more PWM function blocks 266 for detecting that the power converters 210 , 220 may enter a sleep state.

[0079] By keeping one or more PWM functional blocks 255 , 257 , 258 , 259 , 260 deactivated within the switching state 108 , the efficiency of the power converters 210 , 220 may be improved.

[0080] The control circuit 230 may be configured to determine whether a switching condition is met for entering the switching state 108. The switching condition 108 may depend on:

[0081] • operating the switching frequency 103 of the power converters 210 , 220 in the PFM mode 112 ; and / or

[0082] • a load current 123 provided at the output of the power converters 210 , 220 ; and / or

[0083] • The input voltage and / or output voltage 125 of the power converters 210 , 220 .

[0084] The control circuit 230 may be configured to enter the switching state 108 in response to determining that the switching condition is satisfied, thereby providing particularly reliable control of the power converters 210 , 220 .

[0085] The control circuit 230 can be configured to determine that the switching condition is no longer satisfied (after entering the switching state 108). In response to determining that the switching condition is no longer satisfied, one or more PWM function blocks 253, 254, 256 activated within the switching state 108 are deactivated. Additionally, the power converters 210, 220 can be operated in the PFM mode 112 using a set of activated PFM function blocks 231, 232 while the set of PWM function blocks 253, 254, 255, 256, 257, 258, 259, 260 for operation in the PWM mode 111 are inactivated.

[0086] Therefore, the control circuit 230 may be configured to revert to the pure PFM mode 112 in a reliable manner.

[0087] Control circuit 230 may be configured to compare inductor current 301 with a fixed current threshold 305 when operating power converters 210, 220 in PFM mode 112 to generate a turn-off trigger 306 for turning off one or more (high-side) switches of power converters 210, 220. Furthermore, control circuit 230 may be configured to compare inductor current 301 with an adaptive peak current threshold 315 when operating power converters 210, 220 in PFM mode 112 to generate a turn-off trigger 306 for turning off one or more (high-side) switches of power converters 210, 220.

[0088] Furthermore, control circuit 230 may be configured to perform a transition from operating power converters 210, 220 in PFM mode 112 to operating power converters 210, 220 in PWM mode 111 based on fixed current threshold 305 and adaptive current threshold 315. In particular, control circuit 230 may be configured to compare adaptive current threshold 315 with fixed current threshold 305. If (and in particular, once) adaptive current threshold 315 reaches or exceeds fixed current threshold 305, a transition from operating power converters 210, 220 in PFM mode 112 to operating power converters 210, 220 in PWM mode 111 may be performed.

[0089] The control circuit 230 may be configured to determine the adaptive peak current threshold 315 within the switching state 108 using one or more activated PWM functional blocks 253, 254, 256. Thus, a particularly smooth transition from the PFM mode 112 to the PWM mode 111 may be performed.

[0090] The control circuit 230 can be configured to activate one or more PWM function blocks 255, 257, 258, 259, 260 of the set of PWM function blocks 253, 254, 255, 256, 257, 258, 259, 260 that were not activated in the switching state 108 in the context of a transition from operating the power converters 210, 220 in the PFM mode 112 to operating the power converters 210, 220 in the PWM mode 111. In addition, the set of PFM function blocks 231, 232 can be deactivated. Thus, a particularly smooth transition from the PFM mode 112 to the PWM mode 111 can be performed.

[0091] Furthermore, a power converter system 200 is described, which includes power converters 210 , 220 and a control circuit 230 for controlling the power converters 210 , 220 .

[0092] It should be noted that the description and drawings illustrate only the principles of the proposed method and system. Those skilled in the art will be able to implement various arrangements that, although not explicitly described or shown herein, embody the principles of the present invention and are within the spirit and scope of the present invention. In addition, all examples and embodiments summarized in this disclosure are primarily intended to be used for illustrative purposes only to help the reader understand the principles of the proposed method and system. Moreover, all statements herein providing principles, aspects, and embodiments of the present invention, as well as specific examples thereof, are intended to encompass equivalents thereof.

[0093] The present disclosure also includes the following aspects, which are not claims.

[0094] 1. A control circuit for controlling a power converter; wherein the control circuit is configured to:

[0095] - operating the power converter in a pulse frequency modulation (PFM) mode using a set of activated PFM function blocks while a set of PWM function blocks for operating the power converter in a pulse width modulation (PWM) mode is inactivated; and

[0096] - Entering a switching state, in which

[0097] - the power converter operates in PFM mode; and

[0098] One or more PWM function blocks in the group of PWM function blocks are activated.

[0099] 2. The control circuit according to aspect 1, wherein the control circuit is configured to enter a switching state when preparing to switch from operating the power converter in the PFM mode to operating the power converter in the PWM mode.

[0100] 3. The control circuit according to aspect 1 or 2, wherein the one or more PWM function blocks activated in the switching state are configured to:

[0101] - determining a deviation of the output voltage of the power converter from a target voltage; and / or

[0102] - determining an adaptive peak current threshold value for generating a trigger for turning on or off a power switch of the power converter.

[0103] 4. A control circuit according to any one of aspects 1 to 3, wherein the one or more PWM functional blocks activated in the switching state are configured to compare the inductor current flowing through the inductor of the power converter with a peak current threshold to generate a trigger for turning on or off the power switch of the power converter.

[0104] 5. The control circuit according to any one of aspects 1 to 4, wherein the control circuit is configured to keep one or more PWM function blocks in the set of PWM function blocks deactivated in the switching state.

[0105] 6. The control circuit according to aspect 5, wherein the one or more PWM functional blocks that remain disabled in the switching state include:

[0106] - one or more PWM function blocks for generating a clock signal;

[0107] - one or more PWM function blocks for generating a ramp signal; and / or

[0108] - One or more PWM function blocks for detecting that the power converter may enter a sleep state.

[0109] 7. The control circuit according to any one of aspects 1 to 6, wherein the control circuit is configured to:

[0110] - determining that a switching condition is met for entering a switching state; and

[0111] - Entering a switching state in response to determining that the switching condition is satisfied.

[0112] 8. The control circuit according to aspect 7, wherein the switching condition depends on:

[0113] - operating the switching frequency of the power converter in PFM mode; and / or

[0114] - a load current provided at the output of the power converter; and / or

[0115] - Input voltage and / or output voltage of the power converter.

[0116] 9. The control circuit according to aspect 7 or 8, wherein the control circuit is configured to:

[0117] - determining that the switching condition is no longer satisfied; and

[0118] In response to determining that the switching condition is no longer satisfied

[0119] - deactivating one or more PWM function blocks that were activated in the switching state; and

[0120] - operating the power converter in PFM mode with the set of PFM function blocks activated, while the set of PWM function blocks for operation in PWM mode is inactivated.

[0121] 10. The control circuit according to aspect 2 or any one of aspects 3 to 9 when dependent on aspect 2, wherein the control circuit is configured to:

[0122] - when operating the power converter in PFM mode, comparing an inductor current flowing through an inductor of the power converter with a fixed current threshold to generate a turn-off trigger for turning off one or more switches of the power converter;

[0123] - when operating the power converter in PFM mode, comparing the inductor current to an adaptive current threshold to generate a turn-off trigger for turning off one or more switches of the power converter; and

[0124] - performing a transition from operating the power converter in a PFM mode to operating the power converter in a PWM mode in dependence on the fixed current threshold and the adaptive current threshold.

[0125] 11. The control circuit according to aspect 10, wherein the control circuit is configured to:

[0126] - comparing the adaptive current threshold to the fixed current threshold; and

[0127] - If the adaptive current threshold reaches or exceeds the fixed current threshold, performing a transition from operating the power converter in PFM mode to operating the power converter in PWM mode.

[0128] 12. The control circuit according to aspect 10 or 11, wherein the control circuit is configured to determine the adaptive current threshold within the switching state using the activated one or more PWM functional blocks.

[0129] 13. The control circuit according to any one of aspects 10 to 12, wherein the control circuit is configured to determine the adaptive current threshold based on a deviation of the output voltage of the power converter from a target voltage.

[0130] 14. The control circuit according to aspect 2 or any one of aspects 3 to 13 when dependent on aspect 2, wherein the control circuit is configured to, in the context of switching from operating the power converter in PFM mode to operating the power converter in PWM mode,

[0131] - activating one or more PWM function blocks in the set of PWM function blocks that are not activated in the switching state; and / or

[0132] - Deactivate the activated PFM function blocks of this group.

[0133] 15. A power converter system comprising:

[0134] - a power converter; and

[0135] - A control circuit according to any one of aspects 1 to 14, for controlling the power converter.

[0136] 16. A method for controlling a power converter; wherein the method comprises:

[0137] - operating the power converter in a pulse frequency modulation, PFM, mode using a set of activated PFM function blocks while a set of PWM function blocks for operating the power converter in a pulse width modulation, PWM, mode is inactivated; and

[0138] - Entering a switching state, where

[0139] - the power converter operates in PFM mode; and

[0140] One or more PWM function blocks in the group of PWM function blocks are activated.

[0141] 17. The method of aspect 16, wherein the switching state is entered in preparation for switching from operating the power converter in PFM mode to operating the power converter in PWM mode.

Claims

1. A control circuit for controlling a power converter; wherein: The control circuit is configured to: operating the power converter in a pulse frequency modulation (PFM) mode using a set of activated PFM function blocks while a set of PWM function blocks for operating the power converter in a pulse width modulation (PWM) mode is inactivated; and Entering a switching state, in which The power converter operates in the PFM mode; and One or more PWM function blocks in the set of PWM function blocks are activated.

2. The control circuit according to claim 1, wherein: The control circuit is configured to enter the switching state in preparation for transitioning from operating the power converter in the PFM mode to operating the power converter in the PWM mode.

3. The control circuit according to claim 1, wherein: The one or more PWM function blocks activated in the switching state are configured to: determining a deviation of an output voltage of the power converter from a target voltage; and / or An adaptive peak current threshold is determined, the adaptive peak current threshold being used to generate a trigger to turn on or off a power switch of the power converter.

4. The control circuit according to claim 1, wherein: The one or more PWM function blocks activated in the switching state are configured to compare an inductor current through an inductor of the power converter with a peak current threshold to generate a trigger for turning on or off a power switch of the power converter.

5. The control circuit according to claim 1, wherein: The control circuit is configured to keep one or more PWM function blocks in the set of PWM function blocks deactivated in the switching state.

6. The control circuit according to claim 5, wherein: The one or more PWM function blocks that remain deactivated in the switching state include: One or more PWM function blocks for generating a clock signal; One or more PWM function blocks for generating a ramp signal; and / or One or more PWM function blocks for detecting that the power converter may have entered a sleep state.

7. The control circuit according to claim 1, wherein: The control circuit is configured to: Determining that a switching condition for entering a switching state is satisfied; and In response to determining that the switching condition is satisfied, entering the switching state.

8. The control circuit according to claim 7, wherein: The switching conditions depend on: The switching frequency of the power converter operating in the PFM mode; and / or a load current provided at an output of the power converter; and / or The input voltage and / or output voltage of the power converter.

9. The control circuit according to claim 7, wherein: The control circuit is configured to: determining that the switching condition is no longer satisfied; and After determining that the switching condition is no longer satisfied deactivating the one or more PWM function blocks that have been activated in the switching state; and The power converter is operated in the PFM mode using the set of activated PFM function blocks while the set of PWM function blocks for operation in the PWM mode is inactivated.

10. The control circuit according to claim 1, wherein: The control circuit is configured to: When operating the power converter in the PFM mode, comparing an inductor current flowing through an inductor of the power converter with a fixed current threshold to generate a turn-off trigger for turning off one or more switches of the power converter; When operating the power converter in the PFM mode, comparing the inductor current to an adaptive current threshold to generate a turn-off trigger for turning off one or more switches of the power converter; as well as Transitioning from operating the power converter in the PFM mode to operating the power converter in the PWM mode is performed based on the fixed current threshold and the adaptive current threshold.

11. The control circuit according to claim 10, wherein: The control circuit is configured to: comparing the adaptive current threshold to the fixed current threshold; and If the adaptive current threshold reaches or exceeds the fixed current threshold, a transition is performed from operating the power converter in the PFM mode to operating the power converter in the PWM mode.

12. The control circuit according to claim 10, wherein: The control circuit is configured to determine the adaptive current threshold in the switching state using the one or more activated PWM functional blocks.

13. The control circuit according to claim 10, wherein: The control circuit is configured to determine the adaptive current threshold based on a deviation of an output voltage of the power converter from a target voltage.

14. The control circuit according to claim 1, wherein: The control circuit is configured to, in the context of a transition from operating the power converter in the PFM mode to operating the power converter in the PWM mode, activating the one or more PWM function blocks in the group of PWM function blocks that are not activated in the switching state; and / or The set of activated PFM function blocks is deactivated.

15. A power converter system comprising: power converters; and The control circuit for controlling the power converter according to claim 1.

16. A method for controlling a power converter; wherein: The method comprises: operating the power converter in a pulse frequency modulation (PFM) mode using a set of activated PFM function blocks while a set of PWM function blocks for operating the power converter in a pulse width modulation (PWM) mode is inactivated; and Entering a switching state, in which The power converter operates in the PFM mode; and One or more PWM function blocks in the set of PWM function blocks are activated.

17. The method according to claim 16, wherein: The switching state is entered in preparation for transitioning from operating the power converter in the PFM mode to operating the power converter in the PWM mode.

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