Abstract:
A method and apparatus for providing intermittent or interruptible power to an electronic device. The circuit may provide power upon user initiation and interrupt that power in response to a user command, fault state, period of inactivity and so forth. As one example, interruptible power may be initially provided to activate or “power up” an electronic device and constant power provided after the initial activation. The initial powering up of the device may be facilitated by closing two contacts. The circuit may continue to provide power after the button is released through a monitoring and/or feedback mechanism.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation patent application of U.S. Patent Application No. 12/141,715, filed on Jun. 18, 2008 and titled “Momentarily Enabled Electronic Device,” the disclosure of which is hereby incorporated herein in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field 
         [0003]    This invention relates generally to power control for an electronic device, and more particularly to a control mechanism providing momentary power and constant power states. 
         [0004]    2. Background Discussion 
         [0005]    Modern electronic devices may be activated in any number of ways. Some devices may use switches having an on and off position. Others may use buttons that may be pressed down to activate an operational state and depressed to exit the operational state (or vice versa). Still others may use sliders, microswitches and so forth. Typically, such devices require the activating element to travel between an “on” and “off” position and maintain the position selected. Thus, during the entire time the device is active, the activating element maintains its “on” position. 
         [0006]    Should the activating element become stuck or the device inadvertently be left on, the device may remain on until its power source is drained. If the device is battery-powered, this may lead to the replacement of removable batteries, shortening of the life of rechargeable lithium-ion batteries as a charge cycle is consumed, and/or the necessity of recharging the device before it may be used again. Further, certain electronic devices may pose a safety hazard if they are constantly operated for an excessive time. For example, the device may become hot to the touch or may cause deep discharge of a battery, thereby leading to a corrosive acid leak. 
         [0007]    Further, many electronic devices employ an activation mechanism solely to cycle the device between its powered and depowered states. Additional controls may be used to manage device functionality. The use of multiple controls not only may affect the aesthetic of a given electronic device but also increase its operational complexity and thereby the chance for user error. 
       BRIEF SUMMARY 
       [0008]    Generally, one embodiment of the present invention may provide intermittent or interruptible power to an electronic device. The embodiment may provide power upon user initiation and interrupt that power in response to a user command, fault state, period of inactivity and so forth. As one example, interruptible power may be initially provided to activate or “power up” an electronic device and constant power provided after the initial activation. 
         [0009]    The initial powering up of the device may be facilitated by closing two contacts, for example by pressing a button. The embodiment may continue to provide power after the button is released through a monitoring and/or feedback mechanism. As one example, a microcontroller may monitor a status of the button (e.g., open or closed) and a status of a power converter&#39;s power output. Presuming the button is open and the power output is active, the microcontroller may energize a transistor to close a feedback path that, in turn, maintains the power converter in an active state. 
         [0010]    Certain embodiments may provide additional functionality. For example, the switch, button, or other element used to provide interruptible power may initiate different functions when pushed, held closed or otherwise activated for a set period of time. Continuing the example, a button may provide interruptible power to start up or activate an electronic device when pressed and released; the same button may initiate a shutdown or deactivation sequence if pressed and held for at least a minimum time. As yet another example, if pressed multiple times in succession within a sufficiently short time, the button may control some function of the electronic device such as brightness, volume, transmission strength and so on. 
         [0011]    One embodiment takes the form of an apparatus for transmitting power, including: a power input; an activating element connected to the power input; a power converter comprising a first input, second input and output, the power converter connected to the power input at the first input; a voltage source connected to the second input by a central node; and a gate device connected between the output and the central node. 
         [0012]    Another embodiment takes the form of a method for supplying power, including the operations of: closing a contact; in response to closing the contact, activating a power converter; in response to activating the power converter, supplying an output voltage; raising a voltage of a node above a shutdown voltage; and maintaining the output voltage so long as the node voltage exceeds the shutdown voltage. 
         [0013]    Still another embodiment takes the form of a method for supplying power to a device, including the operations of: detecting a button has been pressed; detecting an output voltage from a power converter; detecting the button has been released; and, in response to detecting the button has been released and detecting the output voltage, supplying a base voltage to a base of a transistor, thereby creating a current path through the transistor and maintaining the output voltage of the power converter. 
     
    
     
       BRIEF DESCRIPTIONS OF THE FIGURES 
         [0014]      FIG. 1  depicts a sample operating environment for an embodiment of the present invention. 
           [0015]      FIG. 2  depicts a first embodiment of the present invention. 
           [0016]      FIG. 3  is a state diagram depicting the voltages of various nodes and/or elements of the embodiment of  FIG. 2  at varying times. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    I. Introduction 
         [0018]    Generally, one embodiment of the present invention takes the form of a device, such as a circuit, providing interruptible power to an electronic device. Further, in addition to providing interruptible power, the device may also provide uninterrupted power under certain circumstances. As one example, interruptible power may be initially provided to activate or “power up” an electronic device and constant power provided after the initial activation. 
         [0019]    As used herein, “interruptible power” generally refers to power that is momentarily provided rather than constantly provided. Thus, after some period, the power supply contact or circuit may be broken or opened to suspend power. In other words, “interruptible power” is essentially transient power. Interruptible power may be supplied by closing contacts via a switch or button, for example. 
         [0020]    Certain embodiments may provide additional functionality. For example, the switch, button, or other element used to provide interruptible power may initiate different functions when pushed, held closed or otherwise activated for a set period of time. Continuing the example, a button may provide interruptible power to start up or activate an electronic device when pressed and released; the same button may initiate a shutdown or deactivation sequence if pressed and held for at least a minimum time. 
         [0021]    II. Sample Operating Environment 
         [0022]      FIG. 1  depicts one sample operating environment for an exemplary embodiment. The embodiment  100  may be contained in, for example, a wireless keyboard  105  in communication with a computer  110 . The keyboard  105  may include a power source, such as a battery  115 . The battery may be connected to the embodiment. 
         [0023]    The keyboard  105  may further include operational circuitry  120 . As one example, operational circuitry  120  may include a processor for receiving and interpreting keystrokes or other input, a wireless transmitter to convey data to the computer  110 , a wireless receiver to receive data from the computer and so forth. The operational circuitry may be powered by the battery  115 . However, maintaining the operational circuitry in a constantly-powered mode may rapidly drain the battery charge, thus leading relatively quickly to inoperability of the keyboard  105 . Accordingly, the embodiment  100  may provide power to the operational circuitry  120  only under certain circumstances, such as when a power button is pressed or a power switch closed. Pressing the button or flipping the switch a second time may initiate a shutdown sequence that prevents power from flowing from the battery to the operational circuitry. 
         [0024]    It should be noted that the embodiment  100 , or alternative embodiments, may be used in any number of electronic devices and not just the keyboard  105  depicted in  FIG. 1 . For example, portable computing devices, portable digital storage devices, media players, mobile telephones, and so on all may incorporate an embodiment. Further, the operational circuitry  120  need not provide any particular functionality (such as the wireless communication capabilities discussed with respect to  FIG. 1 ) but merely some functionality that draws power from the battery  115  at least under certain circumstances. 
         [0025]    III. Sample Embodiment 
         [0026]      FIG. 2  depicts one sample embodiment  200 . The embodiment  200  may be electrically and/or operationally connected to a battery  205 , much as shown in the exemplary operating environment of  FIG. 1 . The embodiment may also include a transient connector  210 , such as a switch, button or other element that may selectively close or open an electrical path across the connector. In the embodiment  200  shown in  FIG. 2 , the transient connector  210  is a push button. Accordingly, the remainder of this document will generally discuss the operation of the button  210  as it pertains to the overall operation of the embodiment. However, it should be noted that the term “button” is intended to encompass any form of transient or temporary connector or activating element, specifically including the aforementioned switch. 
         [0027]    A first contact of the button  210  is electrically connected to the battery  205  and a second contact of the button  210  is electrically connected to a first common node  215 . Likewise, an anode of a diode  220  is electrically and/or operationally connected to the first common node  215 . The cathode of the diode  220 , in turn, is electrically connected to a central node  225 . (For simplicity&#39;s sake, the term “connected” as used herein shall be construed to encompass both “operationally connected” and “electrically connected,” unless such construction would render the sentence, embodiment or disclosure meaningless, unpatentable or inoperable.) 
         [0028]    The central node  215  is additionally connected to a capacitor  230 , resistor  235  and emitter of a NPN-doped bipolar junction transistor (BJT)  240 . Although  FIG. 2  depicts a BJT  240 , it should be readily understood that any other form of transistor may be used in lieu of the BJT. Likewise, any such transistor may be either a NPN or PNP doped transistor with appropriate changes to the orientation and connections of the embodiment  200 . The BJT  240  includes three terminals, namely a base, collector and emitter. The central node  215  is also connected to a shutdown input of a DC to DC converter  245 . The function of the converter  245  is discussed in more detail below. 
         [0029]    The DC to DC converter  245  likewise has a power input and a power output. The converter&#39;s power input is connected to the battery  205  via a power input (and thus to the first contact of the button  210 , as shown in  FIG. 2 ). The converter&#39;s output is connected in turn to the collector of the BJT  240  and to a system power input  250 . The function of the system power input  250  is discussed in more detail later. 
         [0030]    The first common node  215  is also connected to a button status input  255 , which is likewise discussed below. A power hold control output  260 , also discussed below, is connected to the base of the BJT  240 . 
         [0031]    In the present embodiment, a microcontroller  265  may accept and/or transmit signals from and to the embodiment  200 , respectively. The microcontroller  265  may monitor and/or coordinate operation of both the operational circuitry  275  and the embodiment. For example, if the embodiment  200  is installed in a wireless device, the microcontroller  265  may act as an interface between a wireless transmitter (and associated circuitry) and the embodiment. The microcontroller may further control the operational circuitry. Continuing the prior example, the microcontroller may determine when and how the wireless transmitter transmits data. In the system shown in  FIG. 2 , the microcontroller  265  includes the aforementioned button status input  255 , system power input  250  and power hold control output  260 . 
         [0032]    The aforementioned capacitor  230  and resistor  235  are connected between the central node  225  and a ground  270 . 
         [0033]    IV. Microcontroller Inputs and Output 
         [0034]    Generally, the button status input  255  permits the microcontroller  265  to monitor whether the button  210  is pressed or free. The button, when pressed, bridges the first contact and the second contact and creates an electrical path between the battery  205  and first common node. Accordingly, if the button is pressed the voltage at the first common node  215  is equal to the battery voltage. When the button is free and therefore not bridging the contacts, the voltage of the first common node is roughly or exactly zero. Since the button status input  255  is connected to the first common node  215 , its voltage equals that of the first common node. 
         [0035]    Thus, when the button  210  is pressed, the voltage of the first common node  215  and associated button status input  255  rise above a default or threshold value (e.g., goes “high”). This threshold value may be, for example, zero. Accordingly, in the status input  255  voltage is high, the microcontroller may presume the button is being pressed. 
         [0036]    The system power input  250  monitors the output of the DC to DC controller  245 . If the output voltage is high (e.g., the converter is operating), then the system power input is high. This, in turn, indicates to the microcontroller that the embodiment  200  is operating to supply power to the microcontroller  265  and operational circuitry. Indeed, the system power input  250  generally provides operating power for the microcontroller  265  and operational circuitry and thus the monitoring function may be considered secondary. In alternative embodiments, the system power input  250  may be used for monitoring only and a separate electrical connection from the output of the controller  245  may provide power to the microcontroller and/or operational circuitry. 
         [0037]    The power hold control output  260  generally is an output of the microcontroller  265 . Voltage may be applied to the base of the BJT  240 , thereby permitting current flow from the collector to the emitter of the BJT. In other words, a sufficient voltage outputted at the power hold control output  260  permits current flow between the output of the converter  245  and the central node  225 , and ultimately through the capacitor  230  and to the ground  270 . Thus, when the BJT is energized by the power hold control output signal, the voltage of the central node  225  is approximately the voltage of the converter output (less any voltage drop across the BJT itself) and the capacitor may obtain or maintain a charge. 
         [0038]    V. The DC to DC Converter 
         [0039]    The DC to DC controller  245  generally converts the input voltage of the battery, as received at the converter&#39;s input terminal, to a constant DC output voltage expressed at the converter&#39;s output terminal. In the present embodiment  200 , the output voltage is regulated to 3.3 volts. It should be appreciated that the actual regulated value of the converter&#39;s output voltage may vary depending on the electronic device in which the embodiment  200  is housed, the power consumption of the operational circuitry and/or microprocessor and so on. 
         [0040]    Additionally, it should be noted that the DC to DC controller  245  only operates if the voltage received at its shutdown input exceeds a minimum voltage. In the present embodiment, the minimum voltage is 0.4 volts. Since the shutdown input is tied directly to the central node  225 , the controller  245  operates only when the central node&#39;s voltage exceeds the minimum value. It should be noted that alternative embodiments or implementations may employ a different minimum voltage. 
         [0041]    When the shutdown input voltage is below the minimum voltage, the battery is still electrically connected to the input terminal of the controller  245 . However, the controller  245  itself floats the input terminal such that no current path exists between the input terminal and the output terminal. Thus, the controller  245  does not draw any battery power if the shutdown input voltage is below the minimum threshold. 
         [0042]    When the shutdown input voltage exceeds the minimum threshold, the controller  245  activates as accepts an input at its input terminal. Accordingly, the battery power is accessed and accepted by the controller  245  in order to provide the aforementioned regulated output voltage (and therefore a regulated DC output current) at its output terminal. 
         [0043]    Given the foregoing, it can be recognized that the voltage at the central node  225  controls whether or not the controller  245  operates, and thus whether the battery power is drained since the battery power generally is not employed by the embodiment  200 , microcontroller  265  or operational circuitry unless the controller  245  is in an operating mode. The next section of this discussion deals generally with operation of the embodiment  200  as well as the manner in which the embodiment sets the voltage at the central node  225 . 
         [0044]    The exact make and model of the DC to DC controller  245  may vary from embodiment to embodiment, as is the case with all elements of the embodiment. Any commercially available converter with the operational characteristics and appropriate inputs/outputs described herein may be employed. It should also be noted that power generally does not “leak” through the system when the central node voltage is below the shutdown input voltage (e.g., the controller  245  is off). Further, the controller  245  generally has a relatively low quiescent power consumption when the embodiment  200  is inactive, although the exact definition of “low quiescent power consumption” may vary in different embodiments, with respect to the supply voltage of the battery, and so on. 
         [0045]    VI. Operation of the Sample Embodiment 
         [0046]    Operation of the embodiment  200  will now be discussed with respect to  FIGS. 2 and 3 . For purposes of this discussion, presume the battery holds a charge above a threshold value. In this example, the threshold value is 0.4 volts, but the threshold may vary in alternative embodiments or implementations. 
         [0047]      FIG. 4  generally depicts the voltage levels of the first common node  215 , central node  225  and DC to DC converter output/system power input  250  at various times during operation of the embodiment  200 . Events occurring at each of the times T 0 , T 1 , T 2 , T 3 , T 4 , T 5  and T 6  are described below, as are the various voltages and operation of the embodiment at each time. 
         [0048]    Initially, at time T 0  the button is not pressed; this is analogous to an initial off state for the embodiment  200 . The battery  205  may have a voltage V, where V typically exceeds the shutdown input voltage. (It should be noted that the battery voltage should generally equal or exceed the shutdown input voltage in order for the circuit to operate.) The voltages of the first common node  215 , central node  225  and system power input are all zero. In some embodiments, the voltage of these nodes and the input may be greater than zero, such as a baseline voltage less than V. Accordingly, references herein to a zero voltage should be understood to encompass a baseline voltage as well. 
         [0049]    At time T 1  a user may press the button  210  to activate the embodiment  200 . This closes the gap between the first contact and second contact, thereby providing battery power and voltage to the first common node  215 . This also provides power and voltage to the button status input  255 , thereby signaling to the microcontroller  265  that the button  210  has been pressed. As shown in  FIG. 3 , at time T 1  the voltage of the first common node rises approximately to the battery voltage V, because the first common node is electrically connected to the battery  205 . In practice, the first common node&#39;s voltage may be somewhat less than V because the button  210  may consume some relatively small amount of voltage. For purposes of this discussion, however, such voltage loss will be ignored. 
         [0050]    Because the voltage of the first common node  215  is non-zero at time T 1 , the button status input to the microcontroller  265  is likewise non-zero. Thus, the microcontroller is informed that the button has been pressed and the corresponding contact is closed. 
         [0051]    Further, given the orientation of the diode  220 , current may flow from the first common node  215  to the central node  225 . The voltage at the central node  225  is likewise equal to the voltage of the first common node and battery  205 , less any voltage drop across the diode  220 . Given the operating voltage of the embodiment  200  and the battery voltage, such voltage drop is relatively negligible. Thus, given a battery  205  with voltage V, the voltage of the central node  225  when the button  210  is pressed is approximately V. 
         [0052]    Raising the voltage of the central node  225  to voltage V has two effects. First, presuming V exceeds 0.4 volts, the controller  245  activates. Second, the voltage differential between the central node and ground  270  begins to charge the capacitor  230 . The resistance value of the resistor  235  generally manipulates the time necessary to charge the capacitor  230  or for the capacitor&#39;s charge to decay, as known to those skilled in the art. Thus, the actual resistance value of the resistor may change as necessary for each embodiment. Likewise, the capacitance of the capacitor  230  may vary. Further, certain embodiments may omit the resistor  235  entirely. 
         [0053]    Still at time T 1 , the controller  245  activates and thus outputs a regulated DC voltage at its output terminal. In the present embodiment, the output voltage of the controller  245  is approximately 3.3 volts. This voltage may vary in alternative embodiments or implementations. With the controller  245  outputting a voltage, the system power input receives the outputted non-zero voltage. Thus, the microcontroller may be informed that the controller  245  is operational. Further, the system power input may now convey power not only to the microcontroller  265 , but also to the operational circuitry  275 . 
         [0054]    Because the button  215  is still pressed at time T 1 , the microcontroller  265  need not supply a voltage at the power hold control output  260 . Accordingly, at time TO the power hold control output typically has no voltage at the base of the transistor  240 . Some embodiments, however, may activate the power hold control output (e.g., create a voltage thereon) at time T 1 . 
         [0055]    Still with reference to  FIGS. 2 and 3 , at time T 2  a user may release the button  210 . Accordingly, at time T 1  the button contacts open and the voltage of the first common node  215  drops to zero. Thus, the button status output voltage likewise drops to zero, informing the microcontroller  265  that the button has been released. 
         [0056]    Although the first common node&#39;s voltage goes to zero at time T 2 , the central node&#39;s voltage does not. The diode  220  prevents current flow from the central node  225  to the first common node  215 , effectively treating the diode  220  as an open leg of a circuit. The capacitor  230  maintains the voltage at the central node  225  above the shutdown input voltage, at least temporarily. Given sufficient time without any current flow through the central node, the capacitor would discharge and the central node&#39;s voltage would drop below the shutdown voltage. 
         [0057]    Because the capacitor maintains the charge of the central node  225  above the shutdown input voltage at time T 2 , the controller  245  continues to operate. Accordingly, the controller  245  draws power from the battery  205  and outputs a DC signal with a regulated voltage at its output terminal. Thus, the system power output remains high (in this sample embodiment, at 3.3 volts) at time T 2 . Accordingly, the microcontroller  265  and operational circuitry  275  both continue to be powered by the embodiment  200 . 
         [0058]    As can be seen, at time T 2  the button status input  255  is a zero voltage and the system power input  250  is a high voltage. The microcontroller  265  may be programmed to recognize this input combination and, in turn, may energize the power hold control output  260 . By supplying voltage at the power hold control output  260  to the base of the transistor  240 , the transistor may allow current flow from the converter  245  output to the central node  225  as discussed above. This, in turn, may maintain the voltage of the central node  225  at that of the converter output, and therefore above the shutdown input voltage and ensure the converter  245  does not deactivate. Further, when the transistor  240  is active in this manner the voltage across the capacitor  230  may remain relatively constant or the capacitor may charge if below its maximum voltage. 
         [0059]    It should be noted that, after time T 2 , the microcontroller  265  need not keep the power hold control output  260  constantly energized (e.g., at a positive non-zero voltage). Rather, the microcontroller  265  may enter a “watchdog” mode in which it only periodically activates the transistor  240  via the power hold control output  260 . The microcontroller  265  may thus reduce overall power consumption and extend the life of the battery  205 . The time intervals between outputting voltage at the power hold control output  260  may vary from embodiment to embodiment, but generally are sufficiently short that the voltage of the central node  225  does not fall beneath the shutdown input voltage. Thus, the length of such intervals may depend, in part, on the capacitance of the capacitor  230 . Of course, alternative embodiments may keep the power hold control output  260  constant and dispense with the aforementioned watchdog mode. 
         [0060]    It should also be noted that the embodiment  200  may provide additional functionality if the button  210  is pressed while the converter  245  is active. Further, because the microcontroller  265  may monitor via the button status input  255  whether or not the button  210  is pressed, certain sequences of button presses may be used to signal to the microcontroller that corresponding functionality should be activated. As one example, repeatedly pressing the button  210  when the converter  245  is active may change an operating parameter of the electronic device incorporating the embodiment  200 . Providing a more specific example, if the electronic device is a wireless keyboard, it may include backlighting functionality to illuminate the keys. The backlighting may be triggered and the illumination adjusted in stages by repeatedly pressing the button. 
         [0061]    It should be appreciated that any function of the electronic device associated with the embodiment  200  may be controlled by sequences of button presses. Further, functionality may be controlled not only by sequences of presses, but also by one or more button presses of varying duration, optionally in combination with such sequences. Returning to the above example, pressing the button  210  for at least a minimum time without releasing it may instruct the microcontroller to begin a sequence of illuminating and/or dimming the backlighting. When the user releases the button, the illumination level may remain at the level present when the button was released. Accordingly, the single input  210  used in the sample embodiment  200  may control more than just a power state of the embodiment. The exact functionality controlled may vary not only with the embodiment but also with the electronic device associated with the embodiment. 
         [0062]    In addition to the above functionality, the embodiment  200  may be deactivated by pressing and holding the button  210  for at least a preset time. This may be combined with the “press-and-hold” functionality immediately previously described in the following manner. If the button is pressed for more than X seconds but less than Y seconds and then released, the microcontroller  265  may interpret this action as a power-down signal. If, however, the button is pressed for more than Y seconds, the microcontroller  265  may interpret the button press as an instruction to access the additional functionality previously described. 
         [0063]    Returning to  FIG. 3 , an example of turning off the embodiment  200  by pressing and holding the button  210  may be seen. At time T 3 , the user may press the button  210  to initiate a power-down sequence. At time T 3 , the converter  245  output remains steady at its regulated high voltage, as does the voltage of the central node  225 . Since pressing the button closes the contacts, the voltage of the first common node  215  jumps from zero to V at T 3 . 
         [0064]    Presume that a length of time X, as shown on  FIG. 3 , is the minimum time the button  210  must be pressed to initiate the power-down sequence. At some time T 4  after the length of time X elapses, the user may release the button  210 . Because the button was pressed for at least the minimum length of time, the microcontroller  265  is instructed to power down the embodiment  200 . (Again, the microcontroller may monitor the status of the button  210  through the button status input  255 .) Accordingly, upon relapse of the button at time T 4 , the voltage of the first common node  215  returns to zero. 
         [0065]    Further, the microcontroller prevents any current from being transmitted along the power hold control output  260  to the base of the BJT  240 . This in turn prevents current flow through the BJT from the converter  245  output to the common node  225 . Accordingly, the converter output no longer maintains a constant voltage at the common node and the capacitor  230  may begin to discharge as shown on  FIG. 4 . Because the capacitor&#39;s charge takes some time to decay, the voltage of the common node may remain above the shutdown input voltage for a period. Accordingly, the converter may continue to operate. 
         [0066]    At time T 5 , however, the voltage of the central node  225  falls below the shutdown input voltage as the capacitor  230  charge decays. (Typically, after time T 4  the voltage of the central node follows the charge decay curve of the capacitor.) Thus, the converter  245  ceases operation and the voltage and current of the converter output, as well as that of the system power input, drops to zero. Therefore, at time T 5  the embodiment  200  no longer provides power to the microcontroller  265  or operational circuitry  275 . Thus, at time T 5  and thereafter the power draw of the electronic device is minimal and the battery life may be conserved. 
         [0067]    Accordingly, it can be seen that the embodiment  200  may begin providing power to at least some operational circuitry  275  when a button  210  is pushed once and cease providing power at approximately the time the button is again pushed. 
         [0068]    VII. Failsafe and Inactivity Operations 
         [0069]    The present embodiment  200  also may power down in the event that the microcontroller or electronic device fails, hangs, or otherwise becomes unresponsive. Typically, any event rendering the electronic device housing the embodiment unresponsive likewise renders the microcontroller  265  unresponsive. The microcontroller, when unresponsive, may not output a current across the power hold control output  260 . This, in turn, de-energizes the transistor  240  and initiates a shut-down sequence automatically with the effects discussed with respect to time T 4  of  FIG. 3 . 
         [0070]    Likewise, the microcontroller may be operationally connected to various inputs of the electronic device. If the electronic device is idle for a minimum period of time, the microcontroller may detect this lack of activity and initiate the power-down sequence. Further, the electronic device may be deactivated, thus deactivating the embodiment  200 , by a user-initiated command or a command initiated by another electronic apparatus associated with the present electronic device. As an example, the embodiment  200  may be contained within a wireless keyboard and a button pressed to power down the keyboard. As a further example, a command may be transmitted from a computer associated with the wireless keyboard to power down the keyboard, for example during power-down operations of the computer itself. 
         [0071]    VIII. Conclusion 
         [0072]    Although the embodiments disclosed herein have been discussed in terms of particular functions, features and elements, it will be readily apparent that certain functions, features and/or elements may be added, omitted or changed without affecting the spirit or scope of the invention. As one example, certain embodiments may replace the button  210  with a microswitch. As yet another example, the various analog circuit elements disclosed herein may be replaced with digital circuit elements. Further, the sample circuit shown in  FIG. 2  may be implemented as an integrated circuit, system on chip, application specific integrated circuit and so forth. As yet another example, the functionality controlled by pressing and/or releasing the button may include wireless transmission (including scaling the strength of transmission), volume or brightness of an electronic device of device&#39;s system, and so on. Accordingly, it should be appreciated that the proper scope of this document is set forth in the claims.