US20130307598A1 - Synchronous state machine with an aperiodic clock - Google Patents

Synchronous state machine with an aperiodic clock Download PDF

Info

Publication number
US20130307598A1
US20130307598A1 US13/473,715 US201213473715A US2013307598A1 US 20130307598 A1 US20130307598 A1 US 20130307598A1 US 201213473715 A US201213473715 A US 201213473715A US 2013307598 A1 US2013307598 A1 US 2013307598A1
Authority
US
United States
Prior art keywords
coupled
circuit
analog
signal
flip
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.)
Granted
Application number
US13/473,715
Other versions
US8581629B1 (en
Inventor
Gary F. Chard
Scott A. Morrison
Susan A. Curtis
Daniel A. King
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Texas Instruments Inc
Original Assignee
Texas Instruments Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Texas Instruments Inc filed Critical Texas Instruments Inc
Priority to US13/473,715 priority Critical patent/US8581629B1/en
Assigned to TEXAS INSTRUMENTS INCORPORATED reassignment TEXAS INSTRUMENTS INCORPORATED ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: CHARD, GARY F., CURTIS, SUSAN A., KING, DANIEL A., MORRISON, SCOTT A.
Application granted granted Critical
Publication of US8581629B1 publication Critical patent/US8581629B1/en
Publication of US20130307598A1 publication Critical patent/US20130307598A1/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

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
    • H02M3/157—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 with digital control
    • 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
    • H02M3/158—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 including plural semiconductor devices as final control devices for a single load
    • H02M3/1582—Buck-boost converters

Definitions

  • the invention relates generally to a state machine and, more particularly, to a synchronous state machine with an aperiodic clock.
  • Boost converters are used in a wide variety of conventional applications, and an example of a conventional boost converter 100 can be seen.
  • the controller 102 is able to control transistors Q 1 and Q 2 (through driver 104 ) so as to generate an output voltage and current at node OUT from an input voltage and current at node IN.
  • the combination of the inductor L 1 and capacitor C 1 (arranged as shown) enable a high voltage to be output node as compared to the voltage at node IN.
  • the current sensor 106 , error amplifiers 110 and 108 , and voltage divider (which is generally comprised of resistors R 1 and R 2 ) can then be used to generate feedback to allow the controller 102 to adjust the pulse widths of the signals applied to transistors Q 1 and Q 2 to achieve the desired current and voltage at node OUT.
  • controller 102 is typically an asynchronous state machine.
  • Asynchronous state machines are usually complex and difficult to design.
  • asynchronous state machines can be very sensitive to its inputs, leading (potentially) to metastable states. Therefore, there is a need for an improved state machine.
  • the present invention accordingly, provides an apparatus.
  • the apparatus comprises an analog timing controller having an analog timing circuit and a glitch filter; and a digital state machine having: an input circuit that is configured to receive a plurality of analog input signals; an analog event circuit that is coupled to the analog timing circuit, the glitch filter, and the input circuit, wherein the analog event circuit and input circuit are configured to generate a composite event signal from the analog input signals and by using the analog timing circuit, and wherein the glitch filter is configured to receive the composite event signal; and a clock generator that is coupled to the glitch filter, wherein the clock generator is configured to generate an aperiodic clock signal, and wherein the aperiodic clock signal is configured to be a synchronous clock signal for the digital state machine.
  • the glitch filter further comprises: an input buffer that is coupled to the analog event circuit; a filter that is coupled to the input buffer; a Schmitt trigger that is coupled to the filter; and an output buffer that is coupled to the Schmitt trigger.
  • the clock generator further comprises: a flip-flop that is coupled to the output buffer; a delay circuit that is coupled to the flip-flop; and a logic circuit that is coupled to between the delay circuit and the flip-flop.
  • the analog timing circuit further comprises a plurality of analog timers.
  • the digital state machine further comprises an enable circuit that is configured to generate a POR signal.
  • the flip-flop further comprises a D flip-flop.
  • the logic circuit that is an OR gate coupled to the delay circuit and that is coupled to the enable circuit so as to receive the POR signal.
  • an apparatus comprising a switching network; an inductor that is coupled to the switching network; a detection circuit that is coupled to the switching network; a driver that is coupled to the switching network; and a controller having: an analog timing controller having an analog timing circuit and a glitch filter; and a digital state machine having: an input circuit that is coupled to the detection circuit; an analog event circuit that is coupled to the analog timing circuit, the glitch filter, and the input circuit, wherein the analog event circuit and input circuit are configured to generate a composite event signal from an output of the detection circuit and by using the analog timing circuit, and wherein the glitch filter is configured to receive the composite event signal; and a clock generator that is coupled to the glitch filter, wherein the clock generator is configured to generate an aperiodic clock signal, and wherein the aperiodic clock signal is configured to be a synchronous clock signal for the digital state machine.
  • an apparatus comprising a switching network having: a first switching node; a first output node; a second switching node; a second output node; a first MOS transistor that is coupled to the first switching node at its drain; a second MOS transistor that is coupled to first output node at its source and the first switching node at its drain; a third MOS transistor that is coupled to the second switching node at its source and the second output node at its drain; and a fourth MOS transistor that is coupled to second output node at its source; an inductor that is coupled between the first and second switching nodes; a detection circuit having: a first comparator that is coupled across the first MOS transistor; a second comparator that is coupled across the fourth transistor; a first error amplifier that is coupled to the first output node and that is configured to receive a first reference signal; and a second error amplifier that is coupled to the second output node and that is configured to receive a second reference signal; a driver that is coupled to the gates
  • FIG. 1 is a diagram of an example of a conventional boost converter employing an asynchronous state machine
  • FIG. 2 is a diagram of an example of a single output multiple output (SIMO) boost converter in accordance with an embodiment of the present invention
  • FIG. 3 is a diagram of an example of the controller of the boost converter of FIG. 2 ;
  • FIG. 4 is a diagram of an example of the glitch filter of FIG. 3 ;
  • FIG. 5 is a diagram of an example of the clock generator of FIG. 3 ;
  • FIG. 6 is a diagram of an example of a state diagram for the controller of FIG. 3 ;
  • FIG. 7 is an example timing diagram depicting an example operation of the controller of FIGS. 2 and 3 .
  • FIGS. 2-5 an example of a SIMO boost converter 200 in accordance with an embodiment of the present invention can be seen.
  • the converter 200 is able to provide multiple output voltages (and currents) while using inductor L 2 , which are provided at output terminals or nodes OUTL and OUTH from the input voltage (at current) at terminal or node IN by way of a switching network (which can, for example, be generally comprised of transistors Q 3 to Q 6 ).
  • a switching network which can, for example, be generally comprised of transistors Q 3 to Q 6 .
  • the voltage at terminal IN can be 5.7V
  • the voltages at nodes OUTL and OUTH can, for example, be positive and negative rail voltages.
  • the inductor L 2 (which can be coupled to switching nodes within the switch network) can be charged in a charge phase or mode, where transistors Q 3 and Q 6 are activated.
  • transistors Q 3 and Q 5 can be activated in a high boost phase to generate the voltage (and current) at terminal OUTH and to charge capacitor C 2 or transistors Q 4 and Q 6 can be activated in a low boost phase to generate the voltage (and current) at terminal OUTL and to charge capacitor C 3 .
  • pulse width modulated (PWM) signals are provided from drivers 204 - 1 and 204 - 2 to the gates of transistors Q 3 to Q 6 (which, for example, can be MOS transistors) to generate the voltages (and currents) at terminals OUTH and OUTL, and the pulse widths of the PWM signals are determined by the controller 202 .
  • the controller 202 generally comprises a digital state machine 302 and an analog timing circuit 304 .
  • the pulse widths can be determined based at least in part on output signals ERN, ERP, RCTP, and RCTN from the detection circuit (which can, for example, be generally comprised of comparators 208 - 1 and 208 - 2 and error amplifiers 210 - 1 and 210 - 2 ).
  • Signals ERN, ERP, RCTP, and RCTN are typically analog signals and are received by the input circuit 312 (which typically samples the analog signals ERN, ERP, RCTP, and RCTN on the rising edge of aperiodic clock signal VCLK).
  • the digital state machine 302 can then process the sampled signals after the next following falling edge of the aperiodic clock signal VCLK, effectively decoupling the noisy analog signals ERN, ERP, RCTP, and RCTN from the state machine 302 and its transitions to increase metastability hardening.
  • the comparators 208 - 1 and 208 - 2 can generally function as rectifier comparators that can generate an output based on the difference between the drain and source voltages of transistors Q 3 and Q 6 (respectively), as reflected by signals RCTP and RCTN (respectively), and comparators 208 - 1 and 208 - 2 can be activated or deactivated by signals ST 1 and ST 2 (respectively) from state output circuit 308 based on the state of the controller 202 .
  • the error amplifiers 210 - 1 and 210 - 2 (which respectively receive reference signals REF 2 and REF 3 ) can determine errors in the voltages on terminals OUTL and OUTH that can indicate errors that can cause the controller 202 (through the FET controller 306 and signals Q 3 D, Q 4 D, Q 5 D, and Q 6 D) to adjust the pulse widths of the PWM signals provided to the gates of transistors Q 3 to Q 6 .
  • Controller 202 is not an asynchronous state machine; instead, the timing controller 304 and timing interface 304 collectively provide an aperiodic clock signal VCLK to allow the controller 202 to operate as a synchronous state machine as indicated above.
  • the timer interface 314 is generally comprised of an analog event circuit 313 and a clock generator 316 .
  • the analog event circuit 313 can, for example, be a logic circuit that determines when to enter and exit particular states, and based at least in part on the signals ERN, ERP, RCTP, and RCTN (which, as shown, are received by the input circuit 312 ) and power-on reset (POR) signal (which itself can be based on enable signal EN), the analog event circuit 313 and the timing circuit 316 (which can include one or more analog resistor-capacitor (RC) timers) can generate composite event signal CE.
  • the rising edges signals RCTP and RCTN can be, in part, used to generate the composite event signal CE.
  • the analog event circuit 313 and timing circuit 316 can be coupled together with a bus that can include one or more analog lines.
  • This composite event signal CE can then be received by the buffer 402 in the glitch filter 318 .
  • the output from buffer 402 can then be filtered by filter 404 (which can, for example, be comprised of transistors Q 7 and Q 8 , resistor R, and capacitor C 4 ), and the filtered output can be used by the Schmitt trigger 406 (which can, for example, be generally comprised of transistors Q 9 to Q 15 ) and buffer 408 to generate signal CEF.
  • This signal CEF can then be provided to the flip-flop 502 (which can for example be a D-type flip-flop) to generate the aperiodic clock signal VCLK.).
  • the analog event circuit 313 and timing circuit 316 can use glitchy and noisy analog signals ERN, ERP, RCTP, and RCTN to generate a signal (composite event signal CE) that can be used to generate a clock signal (aperiodic clock signal VCLK).
  • composite event signal CE composite event signal
  • aperiodic clock signal VCLK aperiodic clock signal
  • the glitch filter 318 can, for example, ensure a minimum high time of the signal and can ensure a minimum output assertion time
  • the flip-flop 502 should not have a clock duty cycle pulse width violation and the aperiodic clock signal should be prevented from going entering a metastable state.
  • Flip-flop 502 is then reset by the output of the OR gate 506 (which receives an output from the delay circuit 504 and the POR signal from the enable circuit 310 .
  • the digital state machine 302 may also include hardware interlock mechanisms (which can, for example, be part of the timer interface 314 ) that can assist in preventing re-arming of timers until all desired state transitions and timer resets have occurred.
  • the timer interface 314 may also include a watchdog timer that can expire when: (a) a particular state is held for too long or is deemed to be a stuck state; (2) an illegal combination of state or logic signals exists for too long; (3) the composite event signal is asserted for too long which might indicate that the clock generation failed to receive the analog event circuit 313 ; or (4) other condition which would be deemed an error condition or hazardous combination of signals or events or lack thereof.
  • FIG. 6 a state diagram for the controller 202 (which is operating as a synchronous state machine using the aperiodic clock signal VCLK) can be seen.
  • the controller 202 is in an idle state 602 until the minimum timer (which can be included as part of the timer interface 314 and which can for example be about 100 ns) lapses in state 604 and an error in the voltages for terminals OUTH and OUTL is detected in stat 604 .
  • the charge phase (an example of which is described above) is entered in state 606 , remaining in this phase until the minimum timer (which can for example be about 200 ns).
  • the controller 202 enters the boost converter 200 into the low boost phase (where the signal ST 2 enables comparator 208 - 2 ) in state 616 for the duration of the minimum timer (i.e., about 100 ns) in state 618 .
  • the boost converter 200 can then remain in the low boost phase until (as shown in state 620 ) the maximum timer (i.e., about 2 ⁇ s) has lapsed or that an edge of signal RCTN is detected.
  • a determination is made in state 632 as to whether an error i.e., signal ERN and/or ERP indicate an error
  • an error i.e., signal ERN and/or ERP indicate an error
  • a determination is made in state 612 as to whether a high side error exists i.e., signal ERP indicates an error.
  • the controller 202 enters the boost converter 200 into the high boost phase (where the signal ST 1 enables comparator 208 - 1 ) in state 624 for the duration of the minimum timer (i.e., about 100 ns) in state 626 .
  • the boost converter 200 can then remain in the high boost phase until (in state 628 ) the maximum timer (i.e., about 2 0 ) has lapsed or that an edge of signal RCTP is detected.
  • a determination is made in state 632 as to whether an error i.e., signal ERN and/or ERP indicate an error
  • the boost converter 200 can remain in the charge phase until the maximum timer (i.e., about 1 ⁇ s) lapses.
  • the controller 202 can enter an indeterminate state, effectively being trapped between states 610 and 612 .
  • the digital state machine 302 includes an arbitration mechanism (which can, for example, be included within the state output circuit 308 ).
  • the arbitration mechanism maintains a record for which terminal (i.e., OUTL or OUTH) was last serviced, and, when errors occur simultaneously (or substantially simultaneously) on both terminals OUTL and OUTH, the arbitration directs the digital state machine 302 to select the terminal OUTH or OUTL that was not serviced during the previous loop.
  • other fairness arbitration methods such as a 50% arbitration mechanism may also be employed.
  • the composite event signal CE can be trigger based on a variety of events (such as an edge of signal RCTP and/or RCTN or the lapsing of a timer set by timing circuit 316 ).
  • the glitch filter 318 is able to de-glitch the signal CE to help prevent undesired switching, and the aperiodic clock VCLK can be generated accordingly.
  • controller 202 can be used as part of boost converter 200 instead of an asynchronous state machine.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Manipulation Of Pulses (AREA)

Abstract

An apparatus is provided. The apparatus includes an analog timing controller and a digital state machine. An input circuit in the digital state machine is configured to receive a plurality of analog input signals, and an analog event circuit is coupled to the analog timing circuit, the glitch filter, and the input circuit. The analog event circuit and input circuit are configured to generate a composite event signal from the analog input signals and by using the analog timing circuit. The glitch filter is configured to receive the composite event signal. A clock generator also is coupled to the glitch filter, wherein the clock generator is configured to generate an aperiodic clock signal. The aperiodic clock signal is configured to be a synchronous clock signal for the digital state machine.

Description

    TECHNICAL FIELD
  • The invention relates generally to a state machine and, more particularly, to a synchronous state machine with an aperiodic clock.
    • BACKGROUND
  • Boost converters are used in a wide variety of conventional applications, and an example of a conventional boost converter 100 can be seen. As shown, the controller 102 is able to control transistors Q1 and Q2 (through driver 104) so as to generate an output voltage and current at node OUT from an input voltage and current at node IN. The combination of the inductor L1 and capacitor C1 (arranged as shown) enable a high voltage to be output node as compared to the voltage at node IN. The current sensor 106, error amplifiers 110 and 108, and voltage divider (which is generally comprised of resistors R1 and R2) can then be used to generate feedback to allow the controller 102 to adjust the pulse widths of the signals applied to transistors Q1 and Q2 to achieve the desired current and voltage at node OUT.
  • One problem with this configuration, however, is that the controller 102 is typically an asynchronous state machine. Asynchronous state machines are usually complex and difficult to design. Moreover, asynchronous state machines can be very sensitive to its inputs, leading (potentially) to metastable states. Therefore, there is a need for an improved state machine.
    • SUMMARY
  • The present invention, accordingly, provides an apparatus. The apparatus comprises an analog timing controller having an analog timing circuit and a glitch filter; and a digital state machine having: an input circuit that is configured to receive a plurality of analog input signals; an analog event circuit that is coupled to the analog timing circuit, the glitch filter, and the input circuit, wherein the analog event circuit and input circuit are configured to generate a composite event signal from the analog input signals and by using the analog timing circuit, and wherein the glitch filter is configured to receive the composite event signal; and a clock generator that is coupled to the glitch filter, wherein the clock generator is configured to generate an aperiodic clock signal, and wherein the aperiodic clock signal is configured to be a synchronous clock signal for the digital state machine.
  • In accordance with the present invention, the glitch filter further comprises: an input buffer that is coupled to the analog event circuit; a filter that is coupled to the input buffer; a Schmitt trigger that is coupled to the filter; and an output buffer that is coupled to the Schmitt trigger.
  • In accordance with the present invention, the clock generator further comprises: a flip-flop that is coupled to the output buffer; a delay circuit that is coupled to the flip-flop; and a logic circuit that is coupled to between the delay circuit and the flip-flop.
  • In accordance with the present invention, the analog timing circuit further comprises a plurality of analog timers.
  • In accordance with the present invention, the digital state machine further comprises an enable circuit that is configured to generate a POR signal.
  • In accordance with the present invention, the flip-flop further comprises a D flip-flop.
  • In accordance with the present invention, the logic circuit that is an OR gate coupled to the delay circuit and that is coupled to the enable circuit so as to receive the POR signal.
  • In accordance with the present invention, an apparatus is provided. The apparatus comprises a switching network; an inductor that is coupled to the switching network; a detection circuit that is coupled to the switching network; a driver that is coupled to the switching network; and a controller having: an analog timing controller having an analog timing circuit and a glitch filter; and a digital state machine having: an input circuit that is coupled to the detection circuit; an analog event circuit that is coupled to the analog timing circuit, the glitch filter, and the input circuit, wherein the analog event circuit and input circuit are configured to generate a composite event signal from an output of the detection circuit and by using the analog timing circuit, and wherein the glitch filter is configured to receive the composite event signal; and a clock generator that is coupled to the glitch filter, wherein the clock generator is configured to generate an aperiodic clock signal, and wherein the aperiodic clock signal is configured to be a synchronous clock signal for the digital state machine.
  • In accordance with the present invention, an apparatus is provided. The apparatus comprises a switching network having: a first switching node; a first output node; a second switching node; a second output node; a first MOS transistor that is coupled to the first switching node at its drain; a second MOS transistor that is coupled to first output node at its source and the first switching node at its drain; a third MOS transistor that is coupled to the second switching node at its source and the second output node at its drain; and a fourth MOS transistor that is coupled to second output node at its source; an inductor that is coupled between the first and second switching nodes; a detection circuit having: a first comparator that is coupled across the first MOS transistor; a second comparator that is coupled across the fourth transistor; a first error amplifier that is coupled to the first output node and that is configured to receive a first reference signal; and a second error amplifier that is coupled to the second output node and that is configured to receive a second reference signal; a driver that is coupled to the gates of the first, second, third, and fourth MOS transistors; and a controller having: an analog timing controller having: an analog timing circuit with a plurality of analog timers; and a glitch filter; and a digital state machine having: an input circuit that is coupled to the first comparator, the second comparator, the first error amplifier, and the second error amplifier; an analog event circuit that is coupled to the analog timing circuit, the glitch filter, and the input circuit, wherein the analog event circuit and input circuit are configured to generate a composite event signal from outputs from the first comparator, the second comparator, the first error amplifier, and the second error amplifier and by using the analog timing circuit, and wherein the glitch filter is configured to receive the composite event signal; a clock generator that is coupled to the glitch filter, wherein the clock generator is configured to generate an aperiodic clock signal, and wherein the aperiodic clock signal is configured to be a synchronous clock signal for the digital state machine; and control circuitry that is coupled to the first comparator, the second comparator, and the driver.
    • BRIEF DESCRIPTION OF THE DRAWINGS
  • For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
  • FIG. 1 is a diagram of an example of a conventional boost converter employing an asynchronous state machine;
  • FIG. 2 is a diagram of an example of a single output multiple output (SIMO) boost converter in accordance with an embodiment of the present invention;
  • FIG. 3 is a diagram of an example of the controller of the boost converter of FIG. 2;
  • FIG. 4 is a diagram of an example of the glitch filter of FIG. 3;
  • FIG. 5 is a diagram of an example of the clock generator of FIG. 3;
  • FIG. 6 is a diagram of an example of a state diagram for the controller of FIG. 3; and
  • FIG. 7 is an example timing diagram depicting an example operation of the controller of FIGS. 2 and 3.
    •  DETAILED DESCRIPTION
  • Refer now to the drawings wherein depicted elements are, for the sake of clarity, not necessarily shown to scale and wherein like or similar elements are designated by the same reference numeral through the several views.
  • Turning to FIGS. 2-5, an example of a SIMO boost converter 200 in accordance with an embodiment of the present invention can be seen. As shown, the converter 200 is able to provide multiple output voltages (and currents) while using inductor L2, which are provided at output terminals or nodes OUTL and OUTH from the input voltage (at current) at terminal or node IN by way of a switching network (which can, for example, be generally comprised of transistors Q3 to Q6). For example, the voltage at terminal IN can be 5.7V, and the voltages at nodes OUTL and OUTH can, for example, be positive and negative rail voltages. To accomplish this, the inductor L2 (which can be coupled to switching nodes within the switch network) can be charged in a charge phase or mode, where transistors Q3 and Q6 are activated. Following the charge phase, transistors Q3 and Q5 can be activated in a high boost phase to generate the voltage (and current) at terminal OUTH and to charge capacitor C2 or transistors Q4 and Q6 can be activated in a low boost phase to generate the voltage (and current) at terminal OUTL and to charge capacitor C3.
  • Typically, pulse width modulated (PWM) signals are provided from drivers 204-1 and 204-2 to the gates of transistors Q3 to Q6 (which, for example, can be MOS transistors) to generate the voltages (and currents) at terminals OUTH and OUTL, and the pulse widths of the PWM signals are determined by the controller 202. The controller 202 generally comprises a digital state machine 302 and an analog timing circuit 304. The pulse widths can be determined based at least in part on output signals ERN, ERP, RCTP, and RCTN from the detection circuit (which can, for example, be generally comprised of comparators 208-1 and 208-2 and error amplifiers 210-1 and 210-2). Signals ERN, ERP, RCTP, and RCTN are typically analog signals and are received by the input circuit 312 (which typically samples the analog signals ERN, ERP, RCTP, and RCTN on the rising edge of aperiodic clock signal VCLK). The digital state machine 302 can then process the sampled signals after the next following falling edge of the aperiodic clock signal VCLK, effectively decoupling the noisy analog signals ERN, ERP, RCTP, and RCTN from the state machine 302 and its transitions to increase metastability hardening. The comparators 208-1 and 208-2 can generally function as rectifier comparators that can generate an output based on the difference between the drain and source voltages of transistors Q3 and Q6 (respectively), as reflected by signals RCTP and RCTN (respectively), and comparators 208-1 and 208-2 can be activated or deactivated by signals ST1 and ST2 (respectively) from state output circuit 308 based on the state of the controller 202. The error amplifiers 210-1 and 210-2 (which respectively receive reference signals REF2 and REF3) can determine errors in the voltages on terminals OUTL and OUTH that can indicate errors that can cause the controller 202 (through the FET controller 306 and signals Q3D, Q4D, Q5D, and Q6D) to adjust the pulse widths of the PWM signals provided to the gates of transistors Q3 to Q6.
  • Controller 202, however, is not an asynchronous state machine; instead, the timing controller 304 and timing interface 304 collectively provide an aperiodic clock signal VCLK to allow the controller 202 to operate as a synchronous state machine as indicated above. As shown in this example, the timer interface 314 is generally comprised of an analog event circuit 313 and a clock generator 316. The analog event circuit 313 can, for example, be a logic circuit that determines when to enter and exit particular states, and based at least in part on the signals ERN, ERP, RCTP, and RCTN (which, as shown, are received by the input circuit 312) and power-on reset (POR) signal (which itself can be based on enable signal EN), the analog event circuit 313 and the timing circuit 316 (which can include one or more analog resistor-capacitor (RC) timers) can generate composite event signal CE. For example, the rising edges signals RCTP and RCTN can be, in part, used to generate the composite event signal CE. Typically, the analog event circuit 313 and timing circuit 316 can be coupled together with a bus that can include one or more analog lines. This composite event signal CE can then be received by the buffer 402 in the glitch filter 318. The output from buffer 402 can then be filtered by filter 404 (which can, for example, be comprised of transistors Q7 and Q8, resistor R, and capacitor C4), and the filtered output can be used by the Schmitt trigger 406 (which can, for example, be generally comprised of transistors Q9 to Q15) and buffer 408 to generate signal CEF. This signal CEF can then be provided to the flip-flop 502 (which can for example be a D-type flip-flop) to generate the aperiodic clock signal VCLK.). Essentially, the analog event circuit 313 and timing circuit 316 can use glitchy and noisy analog signals ERN, ERP, RCTP, and RCTN to generate a signal (composite event signal CE) that can be used to generate a clock signal (aperiodic clock signal VCLK). Also, because the glitch filter 318 can, for example, ensure a minimum high time of the signal and can ensure a minimum output assertion time, the flip-flop 502 should not have a clock duty cycle pulse width violation and the aperiodic clock signal should be prevented from going entering a metastable state. Flip-flop 502 is then reset by the output of the OR gate 506 (which receives an output from the delay circuit 504 and the POR signal from the enable circuit 310. The digital state machine 302 may also include hardware interlock mechanisms (which can, for example, be part of the timer interface 314) that can assist in preventing re-arming of timers until all desired state transitions and timer resets have occurred. The timer interface 314 may also include a watchdog timer that can expire when: (a) a particular state is held for too long or is deemed to be a stuck state; (2) an illegal combination of state or logic signals exists for too long; (3) the composite event signal is asserted for too long which might indicate that the clock generation failed to receive the analog event circuit 313; or (4) other condition which would be deemed an error condition or hazardous combination of signals or events or lack thereof.
  • Turning now to FIG. 6, a state diagram for the controller 202 (which is operating as a synchronous state machine using the aperiodic clock signal VCLK) can be seen. Initially, the controller 202 is in an idle state 602 until the minimum timer (which can be included as part of the timer interface 314 and which can for example be about 100 ns) lapses in state 604 and an error in the voltages for terminals OUTH and OUTL is detected in stat 604. Once an error is detected, the charge phase (an example of which is described above) is entered in state 606, remaining in this phase until the minimum timer (which can for example be about 200 ns). If there is a low side error (i.e., from error amplifier 202-1) is detected in state 610), the controller 202 enters the boost converter 200 into the low boost phase (where the signal ST2 enables comparator 208-2) in state 616 for the duration of the minimum timer (i.e., about 100 ns) in state 618. The boost converter 200 can then remain in the low boost phase until (as shown in state 620) the maximum timer (i.e., about 2 μs) has lapsed or that an edge of signal RCTN is detected. When either of these events occur, a determination is made in state 632 as to whether an error (i.e., signal ERN and/or ERP indicate an error) exists so as to allow the boost converter 200 to reenter the charge phase in state 606 if an error does exist or to the idle state 602 if no error is present. If there is no low side error in state 610, a determination is made in state 612 as to whether a high side error exists (i.e., signal ERP indicates an error). When a high side error is present, the controller 202 enters the boost converter 200 into the high boost phase (where the signal ST1 enables comparator 208-1) in state 624 for the duration of the minimum timer (i.e., about 100 ns) in state 626. The boost converter 200 can then remain in the high boost phase until (in state 628) the maximum timer (i.e., about 2 0) has lapsed or that an edge of signal RCTP is detected. When either of these events occur, a determination is made in state 632 as to whether an error (i.e., signal ERN and/or ERP indicate an error) exists so as to allow the boost converter 200 to reenter the charge phase in state 606 if an error does exist or to the idle state 602 if no error is present. Finally, if no high side error is detected in state 612, the boost converter 200 can remain in the charge phase until the maximum timer (i.e., about 1 μs) lapses.
  • There may also be conditions where an error simultaneously occurs on both terminals OUTL and OUTH. Under these types of conditions, the controller 202 can enter an indeterminate state, effectively being trapped between states 610 and 612. To compensate for such a condition, the digital state machine 302 includes an arbitration mechanism (which can, for example, be included within the state output circuit 308). The arbitration mechanism maintains a record for which terminal (i.e., OUTL or OUTH) was last serviced, and, when errors occur simultaneously (or substantially simultaneously) on both terminals OUTL and OUTH, the arbitration directs the digital state machine 302 to select the terminal OUTH or OUTL that was not serviced during the previous loop. Alternatively, other fairness arbitration methods (such as a 50% arbitration mechanism) may also be employed.
  • As should be apparent from the state diagram of FIG. 6, the composite event signal CE can be trigger based on a variety of events (such as an edge of signal RCTP and/or RCTN or the lapsing of a timer set by timing circuit 316). As shown in FIG. 7, the glitch filter 318 is able to de-glitch the signal CE to help prevent undesired switching, and the aperiodic clock VCLK can be generated accordingly. Thus, the use of a more stable and easily designed synchronous state machine (i.e., controller 202) can be used as part of boost converter 200 instead of an asynchronous state machine.
  • Having thus described the present invention by reference to certain of its preferred embodiments, it is noted that the embodiments disclosed are illustrative rather than limiting in nature and that a wide range of variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure and, in some instances, some features of the present invention may be employed without a corresponding use of the other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.

Claims (20)

1. An apparatus comprising:
an analog timing controller having an analog timing circuit and a glitch filter; and
a digital state machine having:
an input circuit that is configured to receive a plurality of analog input signals;
an analog event circuit that is coupled to the analog timing circuit, the glitch filter, and the input circuit, wherein the analog event circuit and input circuit are configured to generate a composite event signal from the analog input signals and by using the analog timing circuit, and wherein the glitch filter is configured to receive the composite event signal; and
a clock generator that is coupled to the glitch filter, wherein the clock generator is configured to generate an aperiodic clock signal, and wherein the aperiodic clock signal is configured to be a synchronous clock signal for the digital state machine,
wherein the glitch filter further comprises:
an input buffer that is coupled to the analog event circuit
a filter that is coupled to the input buffer;
a Schmitt trigger that is coupled to the filter; and
an output buffer that is coupled to the Schmitt trigger.
2. (canceled)
3. The apparatus of claim 1, wherein the clock generator further comprises:
a flip-flop that is coupled to the output buffer;
a delay circuit that is coupled to the flip-flop; and
a logic circuit that is coupled to between the delay circuit and the flip-flop.
4. The apparatus of claim 3, wherein the analog timing circuit further comprises a plurality of analog timers.
5. The apparatus of claim 4, wherein the digital state machine further comprises an enable circuit that is configured to generate a POR signal.
6. The apparatus of claim 5, wherein the flip-flop further comprise a D flip-flop.
7. The apparatus of claim 6, wherein the logic circuit that is an OR gate coupled to the delay circuit and that is coupled to the enable circuit so as to receive the POR signal.
8. An apparatus comprising:
a switching network;
an inductor that is coupled to the switching network;
a detection circuit that is coupled to the switching network;
a driver that is coupled to the switching network; and
a controller having:
an analog timing controller having an analog timing circuit and a glitch filter; and a digital state machine having:
an input circuit that is coupled to the detection circuit;
an analog event circuit that is coupled to the analog timing circuit, the glitch filter, and the input circuit, wherein the analog event circuit and input circuit are configured to generate a composite event signal from an output of the detection circuit and by using the analog timing circuit, and wherein the glitch filter is configured to receive the composite event signal; and
a clock generator that is coupled to the glitch filter, wherein the clock generator is configured to generate an aperiodic clock signal, and wherein the aperiodic clock signal is configured to be a synchronous clock signal for the digital state machine.
9. The apparatus of claim 8, wherein the glitch filter further comprises:
an input buffer that is coupled to the analog event circuit;
a filter that is coupled to the input buffer;
a Schmitt trigger that is coupled to the filter; and
an output buffer that is coupled to the Schmitt trigger.
10. The apparatus of claim 9, wherein the clock generator further comprises:
a flip-flop that is coupled to the output buffer;
a delay circuit that is coupled to the flip-flop; and
a logic circuit that is coupled to between the delay circuit and the flip-flop.
11. The apparatus of claim 10, wherein the analog timing circuit further comprises a plurality of analog timers.
12. The apparatus of claim 11, wherein the digital state machine further comprises an enable circuit that is configured to generate a power-on-reset (POR) signal.
13. The apparatus of claim 12, wherein the flip-flop further comprise a D flip-flop.
14. The apparatus of claim 13, wherein the logic circuit that is an OR gate coupled to the delay circuit and that is coupled to the enable circuit so as to receive the POR signal.
15. An apparatus comprising:
a switching network having:
a first switching node;
a first output node;
a second switching node;
a second output node;
a first MOS transistor that is coupled to the first switching node at its drain;
a second MOS transistor that is coupled to first output node at its source and the first switching node at its drain;
a third MOS transistor that is coupled to the second switching node at its source and the second output node at its drain; and
a fourth MOS transistor that is coupled to second output node at its source;
an inductor that is coupled between the first and second switching nodes;
a detection circuit having:
a first comparator that is coupled across the first MOS transistor;
a second comparator that is coupled across the fourth transistor;
a first error amplifier that is coupled to the first output node and that is configured to receive a first reference signal; and
a second error amplifier that is coupled to the second output node and that is configured to receive a second reference signal;
a driver that is coupled to the gates of the first, second, third, and fourth MOS transistors; and
a controller having:
an analog timing controller having:
an analog timing circuit with a plurality of analog timers; and
a glitch filter; and
a digital state machine having:
an input circuit that is coupled to the first comparator, the second comparator, the first error amplifier, and the second error amplifier;
an analog event circuit that is coupled to the analog timing circuit, the glitch filter, and the input circuit, wherein the analog event circuit and input circuit are configured to generate a composite event signal from outputs from the first comparator, the second comparator, the first error amplifier, and the second error amplifier and by using the analog timing circuit, and wherein the glitch filter is configured to receive the composite event signal;
a clock generator that is coupled to the glitch filter, wherein the clock generator is configured to generate an aperiodic clock signal, and wherein the aperiodic clock signal is configured to be a synchronous clock signal for the digital state machine; and
control circuitry that is coupled to the first comparator, the second comparator, and the driver.
16. The apparatus of claim 15, wherein the glitch filter further comprises:
an input buffer that is coupled to the analog event circuit;
a filter that is coupled to the input buffer;
a Schmitt trigger that is coupled to the filter; and
an output buffer that is coupled to the Schmitt trigger.
17. The apparatus of claim 16, wherein the clock generator further comprises:
a flip-flop that is coupled to the output buffer;
a delay circuit that is coupled to the flip-flop; and
a logic circuit that is coupled to between the delay circuit and the flip-flop.
18. The apparatus of claim 17, wherein the digital state machine further comprises an enable circuit that is configured to generate a POR signal.
19. The apparatus of claim 18, wherein the flip-flop further comprise a D flip-flop.
20. The apparatus of claim 19, wherein the logic circuit that is an OR gate coupled to the delay circuit and that is coupled to the enable circuit so as to receive the POR signal.
US13/473,715 2012-05-17 2012-05-17 Synchronous state machine with an aperiodic clock Active US8581629B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US13/473,715 US8581629B1 (en) 2012-05-17 2012-05-17 Synchronous state machine with an aperiodic clock

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US13/473,715 US8581629B1 (en) 2012-05-17 2012-05-17 Synchronous state machine with an aperiodic clock

Publications (2)

Publication Number Publication Date
US8581629B1 US8581629B1 (en) 2013-11-12
US20130307598A1 true US20130307598A1 (en) 2013-11-21

Family

ID=49518045

Family Applications (1)

Application Number Title Priority Date Filing Date
US13/473,715 Active US8581629B1 (en) 2012-05-17 2012-05-17 Synchronous state machine with an aperiodic clock

Country Status (1)

Country Link
US (1) US8581629B1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20230129868A1 (en) * 2021-10-21 2023-04-27 Stmicroelectronics S.R.L. Systems and methods for asynchronous finite machines

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20160062331A1 (en) * 2014-08-27 2016-03-03 Freescale Semiconductor, Inc. Apparatus and method for validating the integrity of control signals in timing domain
US10770971B2 (en) 2018-09-26 2020-09-08 Texas Instruments Incorporated Single-input multiple-output (SIMO) converter having a controller with switchable rest states

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6614294B1 (en) * 1999-05-28 2003-09-02 Agere Systems Inc. Filter to remove noise coupling into a sensitive circuit node

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20230129868A1 (en) * 2021-10-21 2023-04-27 Stmicroelectronics S.R.L. Systems and methods for asynchronous finite machines

Also Published As

Publication number Publication date
US8581629B1 (en) 2013-11-12

Similar Documents

Publication Publication Date Title
US8901909B2 (en) Multi-phase power system with redundancy
US7859324B2 (en) Power supply unit
US10063148B2 (en) Switching power supply device having pulse-by-pulse type overcurrent protection function
US7876081B2 (en) DC-DC converter with substantially constant on-time and constant switching frequency
US9385601B2 (en) SMPS with output ripple reduction control and method thereof
US8884599B2 (en) Switching converter control circuit
US9997902B2 (en) Overcurrent protection circuit and switching power apparatus using the same
CN111999623A (en) System and method for monitoring a switching transistor
US20160322902A1 (en) Comparator circuit, power supply control ic, and switching power supply device
US9755514B2 (en) Charge shedding circuit
US8581629B1 (en) Synchronous state machine with an aperiodic clock
JP5994740B2 (en) Switching power supply
JP4089445B2 (en) Semiconductor integrated circuit device
US9501113B2 (en) Voltage detection system and controlling method of the same
US7208987B2 (en) Reset initialization
EP4050803A1 (en) Tracking analog-to-digital converter for power converters
CN116134719A (en) Current limiting technique for buck converter
US9385700B2 (en) Clock monitoring for sequential logic circuits
JP2011069642A (en) Voltage detection circuit
JP7463952B2 (en) Overcurrent detection circuit and switching power supply circuit
JP7375655B2 (en) Pulse edge detection circuit
US11327829B2 (en) Semiconductor device which detects occurrence of an abnormality during operation based on a comparison of an input specifying a PWM signal and an estimated input obtained from an inverse operation
US20230283168A1 (en) Power converter control module
US20140063856A1 (en) Volatge converting apparatus and sub-harmonic detector thereof
JP2015171214A (en) Switching power supply unit

Legal Events

Date Code Title Description
AS Assignment

Owner name: TEXAS INSTRUMENTS INCORPORATED, TEXAS

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:CHARD, GARY F.;MORRISON, SCOTT A.;CURTIS, SUSAN A.;AND OTHERS;SIGNING DATES FROM 20120511 TO 20120514;REEL/FRAME:031358/0558

STCF Information on status: patent grant

Free format text: PATENTED CASE

FPAY Fee payment

Year of fee payment: 4

MAFP Maintenance fee payment

Free format text: PAYMENT OF MAINTENANCE FEE, 8TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1552); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

Year of fee payment: 8