Abstract:
A method and a system for supplying power to a microcontroller with a single cell. One embodiment of the present invention discloses incorporation of a power supply pump circuit with the microcontroller and their dynamic interaction. The microcontroller sends its power requirements to the power supply pump circuit and in response, the power supply pump circuit controls the operating voltage with optimal efficiency. The dynamic update of power supply pump circuit results in an efficient use of the power supply pump circuit and thus results in a reduction of the number of dry cell batteries to only a single cell. Incorporation of the microcontroller and power supply pump circuit onto a single chip reduces the pin number requirements as well as the space required on the printed circuit board.

Description:
RELATED U.S. APPLICATION  
       [0001]     This application claims priority to the copending provisional patent application Ser. No. 60/243,798, Attorney Docket Number CYPR-CD00167, entitled “Advanced Programmable Microcontroller Device,” with filing date Oct. 26, 2000, and assigned to the assignee of the application. 
     
    
     FIELD OF INVENTION  
       [0002]     The present invention relates to the field of power supplies for integrated circuits. More specifically an embodiment of the present invention relates to a power supply pump circuits used to power microcontrollers.  
       BACKGROUND OF THE INVENTION  
       [0003]     A controller is generally a device used to control other processes or external devices. A microcontroller is an electronic device, a highly integrated chip, which performs controlling functions. A microcontroller includes all or most of the parts needed for implementing a controller but physically, is a smaller device (e.g., and integrated circuit). The demands for reduction in the size of microcontrollers, due to the nature of their use, have led to the miniaturization of the electronic components constituting a microcontroller. The reduction in the physical size of microcontrollers has caused an increase in the scope of their use across different fields. The spectrum of the application of microcontrollers varies across different and diverse disciplines. For example, microcontrollers are being used in the field of medicine, for example a pacemaker monitoring a patient&#39;s heart beats, or in the field of meteorology, where a microcontroller is installed in a very remote location to periodically record, log and report atmospheric conditions. In many instances more than one microcontroller is found in a single device to perform a certain function. In today&#39;s technology, almost all electrical and electromechanical devices use microcontrollers for the purpose of controlling or monitoring different processes.  
         [0004]     Microcontrollers require a source of power for their operation. Most microcontrollers only support 4.5 to 5 volts operations and thus require a power source capable of supplying that amount of power. Dry cell batteries are typically used to support a microcontroller&#39;s power demand. To meet such power requirements, generally 2-3 dry cells (e.g., type AAA) power the microcontrollers. Comparing the size of electronic components used in a typical microcontroller and the batteries used to power the device, the batteries are the most voluminous component in a microcontroller. With the ever increasing demand for reduction in the size of microcontrollers, a need exist to reduce the size of the power supply providing power to the microcontrollers.  
         [0005]     Effort should be made to conserve energy during all modes of operation. A typical microcontroller does not operate on a continuous basis, the device is generally programmed to operate based on the demand or in accordance with a programmed schedule. Once the microcontroller performs its function it either goes to an idle mode or to a sleep mode until it is summoned to perform another function. It is during the performance of a function, during operational mode, that a microcontroller requires more power to meet its operating voltage requirements. A microcontroller has a much lower power requirement during its idle or sleep mode than when it is performing a function. For example, a microcontroller which is installed in a remote location to measure environmental data at some-regular interval need not be in its operational mode at all times. The microcontroller may be in its sleep mode most of the time, except when it has to take the environmental data measurements. When measurements are required, the microcontroller wakes up, takes the measurements, logs the data and then goes to sleep. A microcontroller may be placed in a halt mode, where all activities are ceased and it has no power requirements. The only way to wake up the device is by reset or by device interrupt. For example, in a laptop keyboard, where power saving is required, the microcontroller is in halt mode until it detects a keystroke. When the microcontroller detects a keystroke, it wakes up, its mode changes from sleep mode to operation mode. Therefore an efficient method is needed to supply a microcontroller with power on demand and conserve power when the microcontroller is in sleep or idle mode.  
         [0006]     Board space on a typical Printed Circuit Board (PCB) is limited, thus efforts should be made to optimize foot prints of the devices used and the number of pins for inter connection. The present generation of microcontrollers, requiring operating voltage of 4.5-5 volts, uses fewer battery cells than prior generations in order to perform the same or a similar function. To supply the operating voltage requirements with a smaller number of dry cells, a separate power supply pump circuit is used to boost the relatively lower supplied voltage value to the required operating voltage value. A separate power supply pump circuit meets the demand of a microcontroller as far as the operating voltage is concerned, but such a power supply pump circuit has its own disadvantages. A separate power supply pump circuit requires additional space on the printed circuit board (PCB) and additional pins for interconnections. Space on the PCB for any device and pin connections are scarce commodities and efforts are always made to optimize such requirements. Minimizing the space requirements and reducing the number of pins for the interconnection of devices are needs to be addressed by designers and manufacturers.  
         [0007]     To efficiently conserve power, a continuous interaction between a microcontroller and its power supply pump circuit is necessary. Such an interaction includes the microcontroller informing the power supply pump circuit of its power demands and the power supply pump circuit supplying the required power when the power is needed. Conventional power supply pump circuits communicate with microcontroller and supply power to the microprocessor based on the microprocessor&#39;s power demand. However, the very process of communicating (e.g., driving input and output pins) decreases the efficiency of power conservation. Optimal operation of a microcontroller requires efficient communication between the power supply pump circuits and the microcontrollers.  
       SUMMARY OF THE INVENTION  
       [0008]     Therefore, a need exists to minimize the space required by the batteries supplying power to the microcontrollers. Also, a need exist to optimize the efficiency of the communication between the microcontroller and the power supply pump circuit in order to conserve the energy requirements of the microcontrollers. Another need exist to reduce the space required by the power supply pump circuit and the microcontroller on the PCB and to minimize the number of pins required to interconnect these devices. Still another need exist to maintain the microcontroller with minimum amount of power consumption during its sleep mode. The present invention provides a novel solution to these requirements.  
         [0009]     Accordingly, an embodiment of the present invention reduces the size of a power supply pump circuit by reducing a number of battery cells used to supply power to a device. Also, the efficiency of communication between a microcontroller and the power supply pump circuit is increased when both the power supply pump circuit and the microcontroller are integrated into one circuit and are housed in a single chip. Furthermore, integrating the power supply pump circuit and the microcontroller causes a foot print reduction on the PCB, thus satisfies the reduced space requirements, and reduces the number of pins used for interconnection. This invention further optimizes the system&#39;s power consumption due to the dynamic interaction between the two devices (e.g., the microcontroller and the power supply pump circuit). The exchange of information regarding the microcontroller&#39;s power requirements optimizes power consumption by the microcontroller and allows near zero power consumption when the microcontroller is in a sleep mode.  
         [0010]     These and other objects and advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiment which are illustrated in the various drawing figures.  
         [0011]     A method and a system for providing a power supply pump circuit to supply power to a microcontroller. The power supply pump is a part of the microcontroller and the microcontroller dynamically interacts with the power supply pump circuit. A battery initiates a supply of power comprising a certain initial voltage to the power supply pump circuit. This initial voltage establishes a default operating voltage for the power supply pump. A voltage sensor senses the default operating voltage value of the power supply pump circuit. The voltage sensor is a programmable device, and dynamically interacts with the microcontroller to receive power requirements of the microcontroller. The voltage sensor updates the operating voltage value in accordance with the power requirements of the microcontroller. A drive enable receives the operating voltage value from the voltage sensor and maintains the operating voltage value. The power supply pump also includes a gate drive boost circuit. The gate drive boost circuit is configured to receive commands from the drive enable circuit and to fluctuate the operating voltage value according to the commands received from the drive enable circuit. The drive enable circuit regulates the fluctuation of the operating voltage value in accordance with changes in the power requirements of the microcontroller. A passive precharge circuit drives the power supply pump before the voltage sensor and the drive enable begin their normal operation.  
         [0012]     A method and a system for supplying power to a microcontroller with a single cell battery are disclosed. One embodiment of the present invention discloses the incorporation of a power supply pump circuit with the microcontroller and their dynamic interaction. The microcontroller sends its power requirements to the power supply pump circuit, and in response, the power supply pump circuit controls the operating voltage with optimal efficiency. The dynamic update of power supply pump circuit results in an efficient use of the power supply pump circuit, and consequently, a reduction of the number of batteries to only a single cell battery. Incorporation of the microcontroller and power supply pump circuit onto a single chip reduces the number of pins required for connectivity as well as the space required on the printed circuit board.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiment of the invention and, together with the description, serve to explain the principles of the invention:  
         [0014]      FIG. 1  is a block diagram of a typical power supply pump circuit and its interaction with a microcontroller.  
         [0015]      FIG. 2  is exemplary incorporation of a power supply pump circuit and a microcontroller.  
         [0016]      FIG. 3  is a flowchart of the steps in a process of initiating power supply pump operation and supplying the power requirements of a microcontroller.  
         [0017]      FIG. 4  is a flowchart of the steps in a process of a dynamic interaction the power supply pump circuit and a microcontroller.  
         [0018]      FIG. 5  is a flowchart of the steps in a process of initiating power supply pump operation with a single cell.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]     Reference will now be made in detail to preferred embodiment of the invention, a power supply pump circuit for a microcontroller circuit, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with the preferred embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications, and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims. Furthermore, in the following detailed description of the present invention, numerous specified details are set forth in order to provide a thorough understanding of the present invention. However, it will be obvious to one of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well known methods, and circuits have not been described in detail as not to unnecessarily obscure aspects of the present invention.  
         [0020]      FIG. 1  is a block diagram of system.  100  which includes power supply pump system  101  incorporated with microcontroller  180  on a single Integrated Circuit (IC). As depicted in  FIG. 1 , system  101  includes a power supply pump circuit including a ring oscillator  110 , a passive precharge circuit  120 , a drive enable  130 , a gate drive boost  140 , and a voltage sensor  150 . Battery circuit  199  includes a single cell battery  196 , an inductor  195 , a capacitor  198  and a diode  190 . The components  110 - 180  are integrated “on chip” into a single integrated circuit. The components  190 - 198  are “off chip”.  
         [0021]     Ring oscillator  110  generates the clock signals used by logic components of system  101 . Ring oscillator  110  starts operating when V cc    197  attains some nominal initial voltage value, in this embodiment, of approximately 1 Volt. It is appreciated that the Ring oscillator  110  may operate during the sleep mode of microcontroller  180 .  
         [0022]     Passive precharge  120  causes the single cell battery  196  to operate for a short period of time, until V cc    197  reaches an initial minimum voltage for effective gate drive (e.g., approximately 1 Volt). This voltage value causes interaction between all components of the power supply pump circuit  101  and the microcontroller  180 , this voltage is considered as the initial operating voltage. The initial operating voltage is achieved when passive precharge  120  shorts diode  190  causing battery  196 &#39;s current to flow through inductor  195  and charging capacitor  198 . The current from battery  196 , during a short period of time, a transitory period, charges capacitor  198  to the level that it acts as a mini battery and can run ring oscillator  110  long enough to have gate drive boost  140  to start its boosting operation. Passive precharge  120  takes itself out of the circuit as soon as V cc    197  is boosted to the initial operating voltage value, in this embodiment 1 Volt.  
         [0023]     Voltage sensor  150  is a programmable device and selects the operating voltage for the power supply pump circuit. Voltage sensor  150  senses V cc    197  voltage after the transitory period and considers that voltage as the initial operating voltage. At this voltage level, voltage sensor  150  is enabled to interact with drive enable  130 . It is appreciated that V cc    197  voltage is common to all devices of system  101  and battery circuit  199 . When voltage sensor  150  senses the initial operating voltage of 1 volt, Power On Reset Circuit (POR), which is a circuit inside voltage sensor  150  signals the operating status of the microcontroller  180  to voltage sensor  150 . This circuit is a state dependent circuit that notifies voltage sensor  150  whether the microcontroller  180  is waking up or is being initialized.  
         [0024]     There is no interaction between voltage sensor circuit  150  and microcontroller  180  at voltages below the minimum operating voltage of microcontroller  180 . However, interaction between power supply pump circuit  150  and microcontroller  180  commences immediately after the minimum operating voltage of microcontroller  180  is reached. At this voltage level microcontroller  180  configures voltage sensor  150  of its desired parameters including its minimum operating voltage and its future voltage requirements. On the other hand, POR has also notified voltage sensor circuit  150  of microcontroller  180 &#39;s operating status.  
         [0025]     If microcontroller  180  is being initialized, voltage sensor  150  request an increase in initial operating voltage from drive enable  130 . Drive enable  130  commands gate drive boost  140  to start the boosting operation and to continue the boosting operation until drive enable  130  sends a subsequent command to stop the boosting operation. Drive enable  130  sends a command to gate drive boost circuit  140  to stop boosting operation when drive enable  130  is notified by voltage sensor  150  that the minimum operating voltage of the microcontroller  180  has been reached. Microcontroller  180  starts its dynamic interaction with voltage sensor circuit  150  and configures voltage sensor  150  to its desired parameters.  
         [0026]     From this point on voltage sensor  150  notifies drive enable  130  of microprocessor  180 &#39;s voltage requirements and drive enable  130  commands gate drive boost  140  to maintain the required voltage. Gate drive boost  140  receives the voltage requirements from drive enable  130  and fluctuates the voltage by changing the duty cycle of transistor  160  as required. Gate drive boost  140  functions by turning transistor  160  on or off. When transistor  160  is off the current flows into diode  190  and capacitor  198 . Capacitor  198  integrates current into voltage and voltage starts to ramp up. The ramp rate is controlled by the duty cycle of transistor  160 , and is the ratio of transistor  160 &#39;s off time to on time.  
         [0027]     For example, during a start up, Passive Precharge circuit  120  sets V cc    197  equal to 1 Volt. V cc    197  voltage of 1 Volt is common to all devices included in power supply system  101 . When the voltage reaches the minimum operating voltage of microprocessor  180 , dynamic interaction between voltage sensor  150  and microcontroller  180  begins and microcontroller  180  configures voltage sensor  150  with its voltage requirements.  
         [0028]     Gate drive boost  140  receives operating voltage requirements from drive enable  130 . Gate drive boost  140  increases the operating voltage by controlling transistor  160 . Gate drive boost functions by turning transistor  160  on or off. When transistor  160  is off the current flows into diode  190  and capacitor  198 . Capacitor  198  integrates current into voltage and voltage starts to ramp up. The ramp rate is controlled by the duty cycle of transistor  160 , and is the ratio of transistor  160 &#39;s off time to on time.  
         [0029]     In one embodiment of the present invention, the minimum operating voltage of microcontroller  180  is 2.7 volts. drive enable  130  commands gate drive boost  140  to start boosting operation and ramps the voltage. When microcontroller  180  senses 2.7 volts, it initiates a dynamic interaction with voltage sensor  150  and configures Voltage sensor  150  to its desired parameters. Voltage sensor  150  knowing the minimum operating voltage of microcontroller  180  and sensing the voltage value sends a command to drive enable to stop boosting operation until commanded otherwise. From this point on, voltage sensor  150  directs the operating voltage according to microcontroller  180 &#39;s requirements.  
         [0030]     Gate drive boost  140  maintains the operating voltage at 2.7 level until drive enable  130  sends another command requesting change in the operating voltage.  
         [0031]      FIG. 2  shows an exemplary incorporation of a power supply pump circuit  101  and microcontroller  180  in a single Integrated Circuit  210 . In this embodiment of the present invention ring oscillator  110 , drive enable  130 , gate drive boost  140 , voltage sensor  150 , and microcontroller  180  are integrated into a single chip  210 . In this embodiment of the present invention diode  190  is placed inside chip  210 , but diode  190  could be an off chip device or in other embodiments could be eliminated.  
         [0032]     Incorporating power supply pump circuit  101  and microcontroller  180  into a single chip improves communication between the two devices (e.g., microcontroller  180  and power supply pump circuit  100 ). Dynamic interaction between these devices (e.g., ring oscillator  110 , drive enable  130 , gate drive boost  140 , voltage sensor  150 ) is a major factor in optimizing power consumption. Incorporating these two devices (e.g., ring oscillator  110 , drive enable  130 , gate drive boost  140 , voltage sensor  150 ) into a single integrated circuit  210  of  FIG. 2  will result in a more efficient communication. Another advantage of incorporating power supply pump circuit  101  and microcontroller  180  is reduction in the footprint of single integrated circuit  210  of  FIG. 2  on the printed circuit board.  
         [0033]     The present invention provides a single integrated circuit  210  of  FIG. 2  to take the place of a separate power supply pump circuit  101  and microcontroller  180 . The present invention provides diode  190  to be integrated inside single integrated circuit  210  of  FIG. 2 , outside as depicted in  FIG. 2  or could be completely left out. Leaving diode  190  outside single integrated circuit  210  of  FIG. 2  improves the performance of the circuit and is also more cost effective, because a higher quality and a less expensive diode could be used. Furthermore, a single discrete power supply pump circuit  101  has to have a voltage sensor which in and itself consume a fair amount of power. Integration of these devices into a single integrated circuit  210  of  FIG. 2  eliminates such an unnecessary use of power.  
         [0034]     Another advantage of this embodiment of the present invention is that V cc    197  can provide power to devices on the printed circuit board external to system  100 .  
         [0035]      FIG. 3  is a flowchart of the steps of a process  300  of initiating power supply pump operation and dynamic response to the power requirements of a microcontroller.  
         [0036]     In step  310  of  FIG. 3 , the process  300  explains generation of an initial operating voltage of a power supply pump circuit by using a passive precharge circuit for a power supply pump circuit.  
         [0037]     In step  320  of  FIG. 3 , the process  300  shows boosting the initial operating voltage to a minimum operating voltage using a voltage sensor included in the power supply pump circuit, the voltage sensor begins the boosting upon receiving the initial operating voltage.  
         [0038]     In step  330  of  FIG. 3 , the system  300  provides the minimum operating voltage of the power supply to a microcontroller.  
         [0039]     In step  340  of  FIG. 3 , this step of process  300  shows the microcontroller commanding the voltage sensor to maintain the minimum operating voltage or to increase the minimum operating voltage to a higher operating voltage.  
         [0040]      FIG. 4  is a flowchart of the steps of a process  400  of initiating the power supply pump operation and a dynamic response to the power requirements of a microcontroller thus increasing the efficiency of the system.  
         [0041]     In step  410  of  FIG. 4 , the power supply pump circuit and the microcontroller are integrated into a single integrated circuit.  
         [0042]     In step  420  of  FIG. 3 , the power supply pump circuit dynamically interacts with the microcontroller.  
         [0043]     In step  430  of  FIG. 4 , the power supply pump circuit receives a voltage requirement of the microcontroller and efficiently provides the voltage requirements to the microcontroller.  
         [0044]     In step  440  of  FIG. 4 , the power consumption of the microcontroller is optimized when the power supply pump circuit provides voltage to the microcontroller when the microcontroller is in operation mode.  
         [0045]      FIG. 5  is a flowchart of the steps of a process  500  of initiating a power supply pump operation and a dynamic response to the power requirements of a microcontroller, thus optimizing power consumption.  
         [0046]     In step  510  of  FIG. 5 , initial operating voltage is generated by connecting a passive precharge circuit to a battery circuit.  
         [0047]     In step  520  of  FIG. 5 , the initial operation of a drive enable circuit, a voltage sensor circuit, a ring oscillator circuit, and a gate drive boost circuit is initiated at the initial operating voltage.  
         [0048]     In step  530  of  FIG. 5 , the operating voltage is boosted to a minimum operating voltage of microcontroller.  
         [0049]     In step  540  of  FIG. 5 , system  500  shows monitoring the microcontroller&#39;s minimum operating voltage using a voltage sensor device and increasing the minimum operating voltage to a voltage level demanded by the microcontroller.  
         [0050]     The foregoing descriptions of specific embodiments of the present invention have been presented for purpose of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.