US20050194945A1 - Method for Pulse Modulation Control of Switching Regulators - Google Patents
Method for Pulse Modulation Control of Switching Regulators Download PDFInfo
- Publication number
- US20050194945A1 US20050194945A1 US10/908,606 US90860605A US2005194945A1 US 20050194945 A1 US20050194945 A1 US 20050194945A1 US 90860605 A US90860605 A US 90860605A US 2005194945 A1 US2005194945 A1 US 2005194945A1
- Authority
- US
- United States
- Prior art keywords
- side switches
- high side
- switches
- low
- buck
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Images
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
Definitions
- Switching regulators are generally considered to be among the most efficient and versatile available. For typical applications, the efficiency of switching regulators exceeds ninety percent. As shown in FIG. 1 , they may be used to convert voltage upward (boost or step-up configuration). Alternately, and as shown in FIG. 2 , switching regulators may be used to convert voltage downward (buck or step-down configuration). Switching regulators may even be used as shown in FIG. 3 to invert voltage (buck-boost or inverting configuration).
- Switching regulators can generally be classified as either pulse-width-modulation (PWM) or pulse-frequency-modulation (PFM) types.
- PWM regulators produce a pulse train having a fixed frequency and a variable pulse width.
- PFM regulators use a fixed pulse width and a variable pulse frequency.
- various methods have been used to enhance the basic PWM and PFM methods. For many PWM applications, this has resulted in a switch from voltage mode control to current mode control. Current mode control has a number of inherent advantages including faster response to changing loads and ease of combining the output of multiple regulators.
- PFM regulator topologies have been refined to support pulse skipping, hysteretic and burst mode control.
- conventional switching regulators include a feedback loop with an analog error amplifier and comparator as core elements.
- the output of the PWM controller (labeled V fb for feedback voltage) is sent to the error amplifier.
- the output of the error amplifier (labeled V err for error voltage) is the difference between a reference voltage (labeled V ref ) and the feedback voltage V fb .
- V err sets the threshold of a comparator whose other input is connected to a ramp voltage (V ramp ). The output of the comparator drives a switch.
- the present invention includes a method for pulse modulation control of switching regulators.
- a buck-type switching regulator implemented using this method uses a filter capacitor and an inductor. These components are used as they would be in a typical buck-type topology with the filter capacitor in parallel with the regulator load and the inductor positioned in series between the capacitor and the voltage supply.
- a first series of parallel FET-type switches (high-side switches) are positioned between the input side of the inductor and the voltage supply.
- a second parallel series of FET-type switches (low-side switches) are used to connect the input side of the inductor to ground.
- the low-side switches are somewhat analogous to the diode used in typical buck-type topologies.
- a control module enables one or more of the high-side switches synchronously with a system clock at the start of each switching cycle.
- the number of high-side switched enabled is chosen to match the instantaneous load of the buck-type switching regulator.
- the enabled high-side switches remain enabled until the output of the buck-type switching regulator is within regulation or a predetermined current limit through the high-side switches has been exceeded.
- the control module then disables all high-side switches and enables (in a break-before-make fashion) an equivalent number of low-side switches.
- the low-side switches remain enabled until the output of the buck-type switching regulator has fallen below regulation or current has ceased to flow from the inductor to the load of the regulator.
- the pulse modulation control method can used to implement the full range of switching regulator topologies including boost, buck, and boost-buck types.
- FIG. 1 is a block diagram of a prior art boost type switching regulator.
- FIG. 2 is a block diagram of a prior art buck type switching regulator.
- FIG. 3 is a block diagram of a prior art buck-boost type switching regulator.
- FIG. 4A is a block diagram of a feedback loop with an analog error amplifier used to control a prior art buck-boost type switching regulator.
- FIG. 4B is a timing diagram showing the operational performance of the feedback loop of FIG. 4A .
- FIG. 5 is a block diagram of a buck type switching regulator implemented using a pulse modulation control method provided by the present invention.
- FIG. 6 is a timing diagram for the buck type switching regulator of FIG. 5 .
- FIG. 7 is a block diagram showing additional enhancements for the buck type switching regulator of FIG. 5 .
- the present invention includes a method for pulse modulation control of switching regulators.
- the pulse modulation control method can used to implement the full range of switching regulator topologies including boost, buck, and boost-buck types.
- FIG. 5 shows an implementation of a buck-type switching regulator 500 that uses the pulse modulation control method.
- This implementation includes the familiar inductor (labeled L) and capacitor (labeled C) originally shown in FIG. 2 and operates to convert an input voltage V in to an output voltage V out .
- Buck-type switching regulator 500 includes a series of high-side switches labeled 506 a through 506 n.
- Each high-side switch 506 is typically implemented as an FET type device, but other appropriate technologies may also be used.
- High-side switches 506 are functionally analogous to the switch included in the buck-type converter of FIG. 2 and form a link between the input voltage V in and inductor 502 . Selecting the number of high-side switches 506 that are on, controls the rate of current flowing from V in to inductor 502 .
- the rate of current flow between V in to inductor 502 is monitored by an over current sense circuit 508 .
- this is accomplished by monitoring the current following through one of the high-side switches 506 .
- This requires that the monitored high-side switch 506 be used as the primary high-side switch 506 (i.e., any combination of closed high-side switches 506 must include the monitored high-side switch 506 ).
- Over current sense circuit 508 compares the current through the monitored high-side switch 506 to a predetermined limit using a high-speed comparator. When asserted, the output of the comparator indicates that the predetermined current limit has been reached.
- Buck-type switching regulator 500 also includes a series of low-side switches labeled 510 a through 510 n. As with high-side switches 506 , each low-side switch 510 is typically implemented as an FET-type device, but other appropriate technologies may also be used. Low-side switches 510 are functionally analogous to the diode in the buck-type converter of FIG. 2 and form a link between inductor 502 and the ground output of buck-type switching regulator 500 . Selecting the number of low-side switches 510 that are on, controls the rate of current flowing from the ground output to inductor 502 .
- the rate of current flow between V out to inductor 502 is monitored by a reverse current sense circuit 512 .
- this is accomplished by monitoring the current following through one of the low-side switches 510 .
- This requires that the monitored low-side switch 510 be used as the primary low-side switch 510 (i.e., any combination of closed low-side switches 510 must include the monitored low-side switch 510 ).
- Reverse current sense circuit 512 examines the direction of current flowing through the monitored low-side switch 510 . Current flowing from V out to inductor 502 is detected and used to turn low-side switches 510 off.
- the level of V out is monitored by a feedback voltage sense circuit 514 . Typically, this is performed by comparing V out to a reference voltage using a comparator or similar device. The result of this comparison is forwarded to a load detection circuit 516 .
- Load detection circuit 516 also receives the output of over current sense circuit 508 .
- the frequency with which V out is found to be within regulation is compared to the frequency with which the predetermined current limit is exceeded. In insufficient drive situations (i.e., in situations where an inadequate number of high-side switches 506 are being used) the frequency of over current events dominates the frequency of in-regulation events. In lightly loaded situations the frequency of in-regulation events dominates the frequency of over current events.
- Dynamic driver shifter circuit 518 uses this input to construct an output that indicates if the number of active high-side switches 506 and low-side switches 510 should be increased, decreased or maintained as is.
- the output of dynamic driver shifter circuit 518 is passed to an anti-shoot-through switching and digital control module 520 .
- Control module 520 uses this input, and a system clock signal to control the state of high-side switches 506 and low-side switches 510 .
- Control module 520 enables high-side switches 506 synchronously with the system clock.
- the number of high-side switches 506 is determined by the output of dynamic driver shifter circuit 518 .
- the enabled high-side switches 506 remain enabled until: 1) over current sense circuit 508 detects that the predetermined current limit has been exceeded, or 2) feedback voltage sense circuit 514 detects that V out has attained the reference voltage.
- control module 520 disables all high-side switches 506 .
- Control module 520 then enables an equivalent number of low-side switches 510 (i.e., the number of enable low-side switches is equal to the number of previously enabled high-side switches 506 ).
- Low-side switches 510 are enabled after all high-side switches 506 have been disabled in a break-before-make fashion. This avoids shoot through where V in is connected directly to ground.
- the enabled low-side switches 510 remain enabled until: 1) reverse current sense circuit 512 detects current flowing from V out to inductor 502 , or 2) feedback voltage sense circuit 514 detects that V out has fallen below the reference voltage.
- control module 520 disables all low-side switches 510 (once again in a break-before-make fashion) in preparation for enablement of high-side switches 506 at the start of the next clock.
- FIG. 6 shows operation of buck-type switching regulator 500 over several cycles of the system clock.
- control module 520 enables high-side switches 506 a and 506 b at the start of a clock cycle labeled X. This is in response to an indication from dynamic driver shifter circuit 518 that a total of two high-side switches 506 are required to compensate for the instantaneous load of the buck-type switching regulator 500 .
- the third high-side switch 506 c (or 506 n in FIG. 5 ) remains disabled.
- Control module 520 subsequently disables high-side switches 506 a and 506 b after the predetermined current limit has been exceeded, or V out has attained the reference voltage. Once high-side switches 506 a and 506 b have been disabled, control module 520 enables low-side switches 510 a and 510 b. These stay enabled until current starts flowing from V out to inductor 502 or V out has fallen below the reference voltage. The entire cycle is then repeated starting at a clock cycle labeled X+n. In this case, a total of three high-side switches 506 are enabled followed by three low-side switches 510 . This indicates that the load of buck-type switching regulator 500 has increased over the previous switching cycle.
- FIG. 7 shows several enhancements that may be made to improve the performance of buck-type switching regulator 500 .
- These include a maximum on-time controller 522 and a minimum on-time blanker 524 . These two circuits place upper and lower limits (respectively) on the amount of time that high-side switches 504 are enabled. This ensures that the switching cycle is not prolonged indefinitely and prevents transient ringing from causing high-side switches 504 to switch on and off.
- Maximum on-time controller 522 also places a lower bound on the switching frequency of buck-type switching regulator 500 . Preferably, this lower bound is higher than the audio band, ensuring silent operation of buck-type switching regulator 500 .
- the enhancements of FIG. 7 also include a digital soft start 526 that incrementally increases the number of enabled high-side switches 506 active. Typically, this increase is performed at a predetermined rate derived by dividing the frequency of the system clock.
- the soft start function is important during startup to reduce inrush current drawn from the input.
- FIG. 7 also shows a series of enhancements all related to the system clock input. These include: an oscillator or external synchronous phase-locked loop circuit 528 , a pulse skip counter circuit 530 , a synchronous turn on enable circuit 532 and an on/off double pulse suppression latch 534 .
- Oscillator or external synchronous phase-locked loop circuit 528 is a high frequency (e.g., MHz range) low jitter oscillator, phase-locked loop or equivalent circuit that is capable of either generating a stable clock signal or synchronizing to a reference-timing signal.
- the main function of this circuit is to define the switch-on time-edge for the system and also provides the clock timing for other functional blocks.
- Pulse skip counter circuit 530 is used to block out the switching noise of pre-defined frequency bands. This block delays the switch-on time-edge event by skipping the critical frequency range.
- Synchronous turn on enable circuit 532 gates a request-to-turn-on signal with the system clock. This synchronizes the turn-on time-edge of buck-type switching regulator 500 with the system clock.
- On/off double pulse suppression latch 534 latches the switching of high-side switches 506 and low-side switches 510 . This ensures that buck-type switching regulator 500 stays on until deactivated by an off signal and prevents the ringing that might occur if buck-type switching regulator 500 turned off rapidly after being activated.
- Control module 520 provides a flexible mechanism for controlling switching regulator behavior. For example, it is possible to configure control module 520 to avoid undesirable switching frequency bands. This can avoid noise that to which a particular device is sensitive (e.g., 400K to 500K in cellular telephone applications). Synchronous turn-on of high-side switches 506 with the system clock further facilitates noise filtering. In addition, the combination of control module 520 with a variable number of enabled high-side switches 506 and low-side switches 510 provides a combination of low switching loss at light load, fast response to transient load and adaptive current limit for low output ripple at light load.
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
A method for pulse modulation control of switching regulators includes positioning a series of parallel FET-type switches (high-side switches) between the input side of an inductor and the voltage supply. A second parallel series of FET-type switches (low-side switches) are used to connect the input side of the inductor to ground. A control module enables one or more of the high-side switches at the start of each switching cycle. The enabled high side switches remain enabled until the output of the buck-type switching regulator is within regulation or a current limit through the high-side switches has been exceeded. The control module then disables all high-side switches and enables an equivalent number of low-side switches. The low-side switches remain enabled until the output has fallen below regulation or current has ceased to flow from the inductor to the load of the regulator.
Description
- Extending battery life is one of the most important tasks faced by designers of portable electronic systems. This is particularly true for consumer electronics, such as cellular phones, digital cameras, portable computers and other handheld equipment. Designers of these products are faced with a continual need to reduce package size (and battery size) while increasing battery life to match or exceed competitive products. Voltage regulators play an important role in extending battery life. In portable electronic systems, these regulators are used to increase, decrease and invert voltages to perform a wide range of tasks. In portable electronics, the efficiency of these devices is an important, and in some cases crucial consideration.
- Switching regulators are generally considered to be among the most efficient and versatile available. For typical applications, the efficiency of switching regulators exceeds ninety percent. As shown in
FIG. 1 , they may be used to convert voltage upward (boost or step-up configuration). Alternately, and as shown inFIG. 2 , switching regulators may be used to convert voltage downward (buck or step-down configuration). Switching regulators may even be used as shown inFIG. 3 to invert voltage (buck-boost or inverting configuration). - Switching regulators can generally be classified as either pulse-width-modulation (PWM) or pulse-frequency-modulation (PFM) types. PWM regulators produce a pulse train having a fixed frequency and a variable pulse width. PFM regulators, on the other hand, use a fixed pulse width and a variable pulse frequency. Over time, various methods have been used to enhance the basic PWM and PFM methods. For many PWM applications, this has resulted in a switch from voltage mode control to current mode control. Current mode control has a number of inherent advantages including faster response to changing loads and ease of combining the output of multiple regulators. PFM regulator topologies have been refined to support pulse skipping, hysteretic and burst mode control.
- Unfortunately, neither PWM nor PFM types are without disadvantages. As shown in
FIG. 4A , conventional switching regulators (a voltage mode PWM controller in this case) include a feedback loop with an analog error amplifier and comparator as core elements. As shown inFIG. 4A , the output of the PWM controller (labeled Vfb for feedback voltage) is sent to the error amplifier. The output of the error amplifier (labeled Verr for error voltage) is the difference between a reference voltage (labeled Vref) and the feedback voltage Vfb. Verr sets the threshold of a comparator whose other input is connected to a ramp voltage (Vramp). The output of the comparator drives a switch. Greater error voltages increase the comparator threshold on the comparator and increase the amount of time the switch is enabled. As the switch is held on longer, the peak current in the inductor is allowed to climb higher, storing more energy to serve the load and maintain regulation. The relationship is shown graphically inFIG. 4 b. In general, this approach is characterized by low efficiency at light load, slow dynamic response with transients, and loop instability resulting from variations of component values, switching noise injection or insufficient compensational margins. In general, PFM can be used to increase efficiency for light load conditions. Unfortunately, PFM designs are prone to producing electromagnetic noise over a broad spectrum. As a result, there are many applications where PFM cannot be used. For these reasons and others, there is a need for switching regulators that have rapid dynamic response to transients, and do not suffer from loop instability resulting from variations of component values, switching noise injection or insufficient compensational margins. This need is particularly important for applications that cannot tolerate the noise associated with PFM based regulators. - The present invention includes a method for pulse modulation control of switching regulators. A buck-type switching regulator implemented using this method uses a filter capacitor and an inductor. These components are used as they would be in a typical buck-type topology with the filter capacitor in parallel with the regulator load and the inductor positioned in series between the capacitor and the voltage supply. A first series of parallel FET-type switches (high-side switches) are positioned between the input side of the inductor and the voltage supply. A second parallel series of FET-type switches (low-side switches) are used to connect the input side of the inductor to ground. The low-side switches are somewhat analogous to the diode used in typical buck-type topologies.
- A control module enables one or more of the high-side switches synchronously with a system clock at the start of each switching cycle. The number of high-side switched enabled is chosen to match the instantaneous load of the buck-type switching regulator. The enabled high-side switches remain enabled until the output of the buck-type switching regulator is within regulation or a predetermined current limit through the high-side switches has been exceeded. The control module then disables all high-side switches and enables (in a break-before-make fashion) an equivalent number of low-side switches. The low-side switches remain enabled until the output of the buck-type switching regulator has fallen below regulation or current has ceased to flow from the inductor to the load of the regulator.
- The entire switching cycle then repeats with the number of high-side and low-side switches adjusted up, down or held constant depending on the load of the regulator. With appropriate modifications, the pulse modulation control method can used to implement the full range of switching regulator topologies including boost, buck, and boost-buck types.
-
FIG. 1 is a block diagram of a prior art boost type switching regulator. -
FIG. 2 is a block diagram of a prior art buck type switching regulator. -
FIG. 3 is a block diagram of a prior art buck-boost type switching regulator. -
FIG. 4A is a block diagram of a feedback loop with an analog error amplifier used to control a prior art buck-boost type switching regulator. -
FIG. 4B is a timing diagram showing the operational performance of the feedback loop ofFIG. 4A . -
FIG. 5 is a block diagram of a buck type switching regulator implemented using a pulse modulation control method provided by the present invention. -
FIG. 6 is a timing diagram for the buck type switching regulator ofFIG. 5 . -
FIG. 7 is a block diagram showing additional enhancements for the buck type switching regulator ofFIG. 5 . - The present invention includes a method for pulse modulation control of switching regulators. The pulse modulation control method can used to implement the full range of switching regulator topologies including boost, buck, and boost-buck types.
FIG. 5 shows an implementation of a buck-type switching regulator 500 that uses the pulse modulation control method. This implementation includes the familiar inductor (labeled L) and capacitor (labeled C) originally shown inFIG. 2 and operates to convert an input voltage Vin to an output voltage Vout. - Buck-
type switching regulator 500 includes a series of high-side switches labeled 506 a through 506 n. Each high-side switch 506 is typically implemented as an FET type device, but other appropriate technologies may also be used. High-side switches 506 are functionally analogous to the switch included in the buck-type converter ofFIG. 2 and form a link between the input voltage Vin andinductor 502. Selecting the number of high-side switches 506 that are on, controls the rate of current flowing from Vin toinductor 502. - The rate of current flow between Vin to
inductor 502 is monitored by an overcurrent sense circuit 508. Typically, this is accomplished by monitoring the current following through one of the high-side switches 506. This requires that the monitored high-side switch 506 be used as the primary high-side switch 506 (i.e., any combination of closed high-side switches 506 must include the monitored high-side switch 506). Overcurrent sense circuit 508 compares the current through the monitored high-side switch 506 to a predetermined limit using a high-speed comparator. When asserted, the output of the comparator indicates that the predetermined current limit has been reached. - Buck-
type switching regulator 500 also includes a series of low-side switches labeled 510 a through 510 n. As with high-side switches 506, each low-side switch 510 is typically implemented as an FET-type device, but other appropriate technologies may also be used. Low-side switches 510 are functionally analogous to the diode in the buck-type converter ofFIG. 2 and form a link betweeninductor 502 and the ground output of buck-type switching regulator 500. Selecting the number of low-side switches 510 that are on, controls the rate of current flowing from the ground output toinductor 502. - The rate of current flow between Vout to
inductor 502 is monitored by a reversecurrent sense circuit 512. Typically, this is accomplished by monitoring the current following through one of the low-side switches 510. This requires that the monitored low-side switch 510 be used as the primary low-side switch 510 (i.e., any combination of closed low-side switches 510 must include the monitored low-side switch 510). Reversecurrent sense circuit 512 examines the direction of current flowing through the monitored low-side switch 510. Current flowing from Vout toinductor 502 is detected and used to turn low-side switches 510 off. - The level of Vout is monitored by a feedback
voltage sense circuit 514. Typically, this is performed by comparing Vout to a reference voltage using a comparator or similar device. The result of this comparison is forwarded to aload detection circuit 516.Load detection circuit 516 also receives the output of overcurrent sense circuit 508. The frequency with which Vout is found to be within regulation is compared to the frequency with which the predetermined current limit is exceeded. In insufficient drive situations (i.e., in situations where an inadequate number of high-side switches 506 are being used) the frequency of over current events dominates the frequency of in-regulation events. In lightly loaded situations the frequency of in-regulation events dominates the frequency of over current events. - The output of
load detection circuit 516 is passed to a dynamicdriver shifter circuit 518. Dynamicdriver shifter circuit 518 uses this input to construct an output that indicates if the number of active high-side switches 506 and low-side switches 510 should be increased, decreased or maintained as is. - The output of dynamic
driver shifter circuit 518 is passed to an anti-shoot-through switching anddigital control module 520.Control module 520 uses this input, and a system clock signal to control the state of high-side switches 506 and low-side switches 510.Control module 520 enables high-side switches 506 synchronously with the system clock. The number of high-side switches 506 is determined by the output of dynamicdriver shifter circuit 518. The enabled high-side switches 506 remain enabled until: 1) overcurrent sense circuit 508 detects that the predetermined current limit has been exceeded, or 2) feedbackvoltage sense circuit 514 detects that Vout has attained the reference voltage. - At that time,
control module 520 disables all high-side switches 506.Control module 520 then enables an equivalent number of low-side switches 510 (i.e., the number of enable low-side switches is equal to the number of previously enabled high-side switches 506). Low-side switches 510 are enabled after all high-side switches 506 have been disabled in a break-before-make fashion. This avoids shoot through where Vin is connected directly to ground. The enabled low-side switches 510 remain enabled until: 1) reversecurrent sense circuit 512 detects current flowing from Vout toinductor 502, or 2) feedbackvoltage sense circuit 514 detects that Vout has fallen below the reference voltage. At that time,control module 520 disables all low-side switches 510 (once again in a break-before-make fashion) in preparation for enablement of high-side switches 506 at the start of the next clock. -
FIG. 6 shows operation of buck-type switching regulator 500 over several cycles of the system clock. As shown in that figure,control module 520 enables high-side switches driver shifter circuit 518 that a total of two high-side switches 506 are required to compensate for the instantaneous load of the buck-type switching regulator 500. The third high-side switch 506 c (or 506 n inFIG. 5 ) remains disabled. -
Control module 520 subsequently disables high-side switches side switches control module 520 enables low-side switches inductor 502 or Vout has fallen below the reference voltage. The entire cycle is then repeated starting at a clock cycle labeled X+n. In this case, a total of three high-side switches 506 are enabled followed by three low-side switches 510. This indicates that the load of buck-type switching regulator 500 has increased over the previous switching cycle. -
FIG. 7 shows several enhancements that may be made to improve the performance of buck-type switching regulator 500. These include a maximum on-time controller 522 and a minimum on-time blanker 524. These two circuits place upper and lower limits (respectively) on the amount of time that high-side switches 504 are enabled. This ensures that the switching cycle is not prolonged indefinitely and prevents transient ringing from causing high-side switches 504 to switch on and off. Maximum on-time controller 522 also places a lower bound on the switching frequency of buck-type switching regulator 500. Preferably, this lower bound is higher than the audio band, ensuring silent operation of buck-type switching regulator 500. - The enhancements of
FIG. 7 also include a digital soft start 526 that incrementally increases the number of enabled high-side switches 506 active. Typically, this increase is performed at a predetermined rate derived by dividing the frequency of the system clock. The soft start function is important during startup to reduce inrush current drawn from the input. -
FIG. 7 also shows a series of enhancements all related to the system clock input. These include: an oscillator or external synchronous phase-lockedloop circuit 528, a pulseskip counter circuit 530, a synchronous turn on enablecircuit 532 and an on/off double pulse suppression latch 534. Oscillator or external synchronous phase-lockedloop circuit 528 is a high frequency (e.g., MHz range) low jitter oscillator, phase-locked loop or equivalent circuit that is capable of either generating a stable clock signal or synchronizing to a reference-timing signal. The main function of this circuit is to define the switch-on time-edge for the system and also provides the clock timing for other functional blocks. - Pulse
skip counter circuit 530 is used to block out the switching noise of pre-defined frequency bands. This block delays the switch-on time-edge event by skipping the critical frequency range. - Synchronous turn on enable
circuit 532 gates a request-to-turn-on signal with the system clock. This synchronizes the turn-on time-edge of buck-type switching regulator 500 with the system clock. - On/off double pulse suppression latch 534 latches the switching of high-side switches 506 and low-side switches 510. This ensures that buck-
type switching regulator 500 stays on until deactivated by an off signal and prevents the ringing that might occur if buck-type switching regulator 500 turned off rapidly after being activated. -
Control module 520 provides a flexible mechanism for controlling switching regulator behavior. For example, it is possible to configurecontrol module 520 to avoid undesirable switching frequency bands. This can avoid noise that to which a particular device is sensitive (e.g., 400K to 500K in cellular telephone applications). Synchronous turn-on of high-side switches 506 with the system clock further facilitates noise filtering. In addition, the combination ofcontrol module 520 with a variable number of enabled high-side switches 506 and low-side switches 510 provides a combination of low switching loss at light load, fast response to transient load and adaptive current limit for low output ripple at light load. - Although particular embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art that changes and modifications may be made without departing from the present invention in its broader aspects, and therefore, the appended claims are to encompass within their scope all such changes and modifications that fall within the true scope of the present invention.
Claims (10)
1. A method for pulse modulation control of a switching regulator where the switching regulator include a parallel series of m high side switches and a parallel series of m low side switches, the method comprising:
a) closing n high side switches within the parallel series of m high side switches where n is less than or equal to m;
b) opening each high side switch closed in step a;
c) closing n low side switches within the parallel series of m low side switches;
d) opening each low side switch closed in step c; and
e) repeating steps a though e while varying the number n to maintain the output of the regulator at a desired voltage or current level.
2. A method as recited in claim 1 where the switching regulator is selected from a group consisting of buck, boost and buck boost types.
3. A method as recited in claim 1 which further comprises the step of opening all low side switches when a reverse current condition is detected within the switching regulator.
4. A method as recited in claim 1 where the step of closing the high side switches is performed synchronously with a system clock and where the step of opening the high side switches is timed to occur no more than a predetermined number of cycles later.
5. A method as recited in claim 4 where the steps of closing and opening the high side switches is controlled to avoid a predetermined switching frequency.
6. A pulse modulation controller for a switching regulator, the controller comprising:
a parallel series of m high side switches;
a parallel series of m low side switches;
a controller configured to:
a) close n high side switches within the parallel series of m high side switches where n is less than or equal to m;
b) open each high side switch closed in step a;
c) close n low side switches within the parallel series of m low side switches;
d) open each low side switch closed in step c; and
e) repeat steps a though e while varying the number n to maintain the output of the regulator at a desired voltage or current level.
7. A pulse modulation controller as recited in claim 6 where the switching regulator is selected from a group consisting of buck, boost and buck boost types.
8. A pulse modulation controller as recited in claim 6 where the controller is configured to opening all low side switches when a reverse current condition is detected within the switching regulator.
9. A pulse modulation controller as recited in claim 6 where the controller is configured to:
close the high side switches synchronously with a system clock; and
open the high side switches no more than a predetermined number of cycles later.
10. A pulse modulation controller as recited in claim 9 where controller selectively skips one or more switching frequency bands when controlling the opening and closing of the high side switches.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/908,606 US20050194945A1 (en) | 2003-07-09 | 2005-05-18 | Method for Pulse Modulation Control of Switching Regulators |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/616,382 US7026795B2 (en) | 2003-07-09 | 2003-07-09 | Method for pulse modulation control of switching regulators |
US10/908,606 US20050194945A1 (en) | 2003-07-09 | 2005-05-18 | Method for Pulse Modulation Control of Switching Regulators |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/616,382 Continuation US7026795B2 (en) | 2003-07-09 | 2003-07-09 | Method for pulse modulation control of switching regulators |
Publications (1)
Publication Number | Publication Date |
---|---|
US20050194945A1 true US20050194945A1 (en) | 2005-09-08 |
Family
ID=33564752
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/616,382 Expired - Lifetime US7026795B2 (en) | 2003-07-09 | 2003-07-09 | Method for pulse modulation control of switching regulators |
US10/908,606 Abandoned US20050194945A1 (en) | 2003-07-09 | 2005-05-18 | Method for Pulse Modulation Control of Switching Regulators |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/616,382 Expired - Lifetime US7026795B2 (en) | 2003-07-09 | 2003-07-09 | Method for pulse modulation control of switching regulators |
Country Status (1)
Country | Link |
---|---|
US (2) | US7026795B2 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7728567B1 (en) * | 2007-01-26 | 2010-06-01 | Atheros Communications, Inc. | Current mode pulse frequency modulation switching regulator |
CN102377335A (en) * | 2010-08-16 | 2012-03-14 | 登丰微电子股份有限公司 | Transistor module and transistor driving module |
US20130027980A1 (en) * | 2007-07-06 | 2013-01-31 | Advanced Analogic Technologies, Inc. | DC/DC Converter Using Synchronous Freewheeling MOSFET |
Families Citing this family (16)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7345464B2 (en) * | 2004-09-16 | 2008-03-18 | Semiconductor Components Industries, L.L.C. | PWM power supply controller having multiple PWM signal assertions and method therefor |
TWM313378U (en) * | 2006-10-20 | 2007-06-01 | Holtek Semiconductor Inc | Digital-to-analog conversion circuit applicable to power soft-switching circuit architecture |
JP5130542B2 (en) * | 2008-03-13 | 2013-01-30 | Nec東芝スペースシステム株式会社 | Step-down switching DC / DC converter |
JP4738442B2 (en) * | 2008-05-28 | 2011-08-03 | 株式会社東芝 | DC-DC converter |
JP4762274B2 (en) * | 2008-07-16 | 2011-08-31 | 株式会社東芝 | Semiconductor device |
US7777587B2 (en) * | 2008-08-06 | 2010-08-17 | International Rectifier Corporation | Minimum pulse width for pulse width modulation control |
JP2011100953A (en) * | 2009-11-09 | 2011-05-19 | Toshiba Corp | Semiconductor device and dc-dc converter |
US9166028B2 (en) * | 2011-05-31 | 2015-10-20 | Infineon Technologies Austria Ag | Circuit configured to adjust the activation state of transistors based on load conditions |
KR101259894B1 (en) * | 2012-03-26 | 2013-05-02 | 주식회사 동부하이텍 | Pfm control apparatus for single inductor dual output power circuit and pfm control method therefor |
US8988059B2 (en) | 2013-01-28 | 2015-03-24 | Qualcomm Incorporated | Dynamic switch scaling for switched-mode power converters |
US10193442B2 (en) | 2016-02-09 | 2019-01-29 | Faraday Semi, LLC | Chip embedded power converters |
US10504848B1 (en) | 2019-02-19 | 2019-12-10 | Faraday Semi, Inc. | Chip embedded integrated voltage regulator |
US11069624B2 (en) | 2019-04-17 | 2021-07-20 | Faraday Semi, Inc. | Electrical devices and methods of manufacture |
US11063516B1 (en) | 2020-07-29 | 2021-07-13 | Faraday Semi, Inc. | Power converters with bootstrap |
US11848610B2 (en) | 2021-08-03 | 2023-12-19 | Analog Devices, Inc. | Low ripple pulse-skip mode control in switching mode power supplies |
US11990839B2 (en) | 2022-06-21 | 2024-05-21 | Faraday Semi, Inc. | Power converters with large duty cycles |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6362608B1 (en) * | 2001-02-01 | 2002-03-26 | Maxim Integrated Products, Inc. | Multi-phase switching converters and methods |
US6366062B2 (en) * | 1997-12-08 | 2002-04-02 | Microplanet, Inc. | Method and apparatus for electronic power control |
US6373250B1 (en) * | 2000-05-19 | 2002-04-16 | Ramot University Authority For Applied Research And Industrial Development Ltd. | Method of magnetic resonance imaging |
US6373728B1 (en) * | 1999-09-27 | 2002-04-16 | Grundfos A/S | Frequency converter with an intermediate buck-boost converter for controlling an electric motor |
US6597157B1 (en) * | 2001-07-25 | 2003-07-22 | 3Dlabs, Inc., Ltd | Parallel phased switch control |
US6788033B2 (en) * | 2002-08-08 | 2004-09-07 | Vlt, Inc. | Buck-boost DC-DC switching power conversion |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6396250B1 (en) * | 2000-08-31 | 2002-05-28 | Texas Instruments Incorporated | Control method to reduce body diode conduction and reverse recovery losses |
-
2003
- 2003-07-09 US US10/616,382 patent/US7026795B2/en not_active Expired - Lifetime
-
2005
- 2005-05-18 US US10/908,606 patent/US20050194945A1/en not_active Abandoned
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6366062B2 (en) * | 1997-12-08 | 2002-04-02 | Microplanet, Inc. | Method and apparatus for electronic power control |
US6373728B1 (en) * | 1999-09-27 | 2002-04-16 | Grundfos A/S | Frequency converter with an intermediate buck-boost converter for controlling an electric motor |
US6373250B1 (en) * | 2000-05-19 | 2002-04-16 | Ramot University Authority For Applied Research And Industrial Development Ltd. | Method of magnetic resonance imaging |
US6362608B1 (en) * | 2001-02-01 | 2002-03-26 | Maxim Integrated Products, Inc. | Multi-phase switching converters and methods |
US6597157B1 (en) * | 2001-07-25 | 2003-07-22 | 3Dlabs, Inc., Ltd | Parallel phased switch control |
US6788033B2 (en) * | 2002-08-08 | 2004-09-07 | Vlt, Inc. | Buck-boost DC-DC switching power conversion |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7728567B1 (en) * | 2007-01-26 | 2010-06-01 | Atheros Communications, Inc. | Current mode pulse frequency modulation switching regulator |
US20130027980A1 (en) * | 2007-07-06 | 2013-01-31 | Advanced Analogic Technologies, Inc. | DC/DC Converter Using Synchronous Freewheeling MOSFET |
US8847564B2 (en) * | 2007-07-06 | 2014-09-30 | Advanced Analogic Technologies, Incorporated | DC/DC converter using synchronous freewheeling MOSFET |
CN102377335A (en) * | 2010-08-16 | 2012-03-14 | 登丰微电子股份有限公司 | Transistor module and transistor driving module |
Also Published As
Publication number | Publication date |
---|---|
US7026795B2 (en) | 2006-04-11 |
US20050007796A1 (en) | 2005-01-13 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US20050194945A1 (en) | Method for Pulse Modulation Control of Switching Regulators | |
US10312811B2 (en) | Method to recover from current loop instability after cycle by cycle current limit intervention in peak current mode control | |
KR101946386B1 (en) | Current mode pwm boost converter | |
KR100874284B1 (en) | DC-DC Converters, Electronic Devices, Methods and Step-Up DC-DC Converters | |
EP1248352B1 (en) | Circuits and methods for synchronizing non-constant frequency switching regulators with a phase locked loop | |
US7208921B2 (en) | DC-DC regulator with switching frequency responsive to load | |
USRE46045E1 (en) | Hysteretic controlled buck-boost converter | |
US6628106B1 (en) | Control method and circuit to provide voltage and current regulation for multiphase DC/DC converters | |
US8310216B2 (en) | Synchronous rectifier control for synchronous boost converter | |
US7956586B2 (en) | Step-up/step-down type DC-DC converter, and control circuit and control method of the same | |
US20210083583A1 (en) | Seamless dcm-pfm transition for single pulse operation in dc-dc converters | |
WO2007044583A1 (en) | Low loss switching mode power converter operating in both ccm and dcm | |
GB2483002A (en) | DC-DC converter having inhibited low side switch | |
US9667144B2 (en) | DC-DC converter with reverse current detecting circuit | |
EP2020076A2 (en) | Startup for dc/dc converters | |
US8164319B2 (en) | System and method for adapting clocking pulse widths for DC-to-DC converters | |
KR102453380B1 (en) | Boost dc-dc converter using dsm, duty ratio controller for the boost dc-dc converter, and a method for configuring the duty ratio controller | |
US10720839B1 (en) | System and method for operating a switching converter in light load | |
US20060022653A1 (en) | System and method to mitigate transient energy | |
JP2008509643A (en) | Converter circuit with forward and backward control | |
US10243464B2 (en) | Power regulator with prevention of inductor current reversal | |
CN113437870B (en) | DC-DC converter, mode switching method and circuit thereof, and electronic device | |
JP2006238603A (en) | Switching regulator |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |