Abstract:
A device for driving a power supply start-up circuit may include a logic unit for storing an operating state of equipment, where the logic unit is activatable by a start-up signal reaching a start-up threshold. The device may also include a detector, where the detector provides a signal to the logic unit indicating a drop in the signal below a drop threshold. The detector may enable the logic unit to continue operating in the presence of a failure of a power supply to store the operating state of the equipment upon occurrence of the failure of the power supply. In addition, the device may include a start-up circuit sensitive to a power supply signal, where the start-up circuit is activatable by the power supply signal as restored after the failure, and the start-up circuit may provide the start-up signal reaching the start-up threshold upon the power supply signal being restored.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates to operational state recovery in electronic equipment, and, more particularly, to a device to recover the operational state of remote-controlled equipment with zero power consumption while in stand-by. 
       BACKGROUND 
       [0002]    Equipment such as an electronic appliance capable of achieving “zero” consumption during stand-by may comply with various criteria. For instance, the system may default to an inactive (zero consumption) state when plugged and/or the circuit modules including any logic units may be shut down (turned off) when the system is inactive. 
         [0003]    Also, activating the system when inactive may involve a human intervention, for example, a remote control unit (InfraRed—IR or RadioFrequency—RF) or a start button to generate a dedicated start-up signal (“start-up stimuli”) acting on a dedicated zero-stand-by start-up circuit for the power supply. Such a circuit may include, e.g., a Switched-Mode Power Supply (SMPS) which may start-up if a voltage VSTUP goes above a start-up threshold VTHstup (e.g. around 12V). In certain implementations, the system may be able to keep running after start-up without the contribution of the start-up circuit itself. 
       SUMMARY 
       [0004]    A basic drawback of certain implementations may lie in that after a failure the system defaults to an inactive state, so that a new start-up intervention may be required in order to recover a previous operation. 
         [0005]    The need is thus felt for improved arrangements which may address that drawback. 
         [0006]    According to one aspect, a device for driving a power supply start-up circuit for equipment fed with a power supply signal over a power supply line may include a logic unit for storing the operating state of the equipment, where the logic unit is activatable by a start-up signal over a start-up line reaching a start-up threshold. 
         [0007]    The device may also include a detector coupled to the start-up line, where the detector provides to the logic unit a signal indicating a drop in the signal over the start-up line below a drop threshold. The detector may enable the logic unit to continue operating in the presence of a failure of the power supply signal on the power supply line to store the operating state of the equipment upon occurrence of a failure of the power supply signal. In addition, the device may include a start-up circuit sensitive to the power supply signal on the power supply line, where the start-up circuit is activatable by the power supply signal on the power supply line as restored after a failure, and the start-up circuit may provide the start-up signal reaching the start-up threshold upon the power supply signal being restored. 
         [0008]    One or more embodiments may permit operational state recovery after a main failure (e.g. blackout) for an electronic appliance with zero consumption when inactive (zero stand-by). 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0009]    One or more embodiments will now be described, purely by way of non-limiting example, with reference to the annexed figures, wherein: 
           [0010]      FIG. 1  is a schematic block diagram of a device for driving a power supply start-up circuit in a particular embodiment; 
           [0011]      FIG. 2  is a schematic block diagram of the device that includes a voltage detector in a particular embodiment; 
           [0012]      FIG. 3  is a schematic block diagram of the device that includes a start-up circuit in a particular embodiment; and 
           [0013]      FIG. 4  is a schematic block diagram that includes details of the start-up circuit of  FIG. 3  in a particular illustrative embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    In the ensuing description one or more specific details are illustrated, aimed at providing an in-depth understanding of examples of embodiments. The embodiments may be obtained without one or more of the specific details, or with other methods, components, materials, etc. In other cases, known structures, materials, or operations are not illustrated or described in detail so that certain aspects of embodiments will not be obscured. 
         [0015]    Reference to “an embodiment” or “one embodiment” in the framework of the present description is intended to indicate that a particular configuration, structure, or characteristic described in relation to the embodiment is comprised in at least one embodiment. Hence, phrases such as “in an embodiment” or “in one embodiment” that may be present in one or more points of the present description do not necessarily refer to one and the same embodiment. Moreover, particular conformations, structures, or characteristics may be combined in any adequate way in one or more embodiments. 
         [0016]    The references used herein are provided merely for convenience and hence do not define the scope of protection or the scope of the embodiments. 
         [0017]    The diagrams in the figures are generally illustrative of a system for activating associated equipment (e.g., an electronic appliance fed with a power supply signal VL over a power supply line) by means of a power supply start-up circuit including, for example, a Switched-Mode Power Supply (SMPS) of any known type. In one or more embodiments, the power supply start-up circuit may be included in the equipment  10  fed with the power supply signal VL. 
         [0018]    While in the figures enclosed herewith the power supply start-up circuit is assumed to be included in the associated equipment (so that the reference  10  may be indicative of both), in one or more embodiments the power supply start-up circuit may be a separate element operatively connected to the associated equipment. 
         [0019]    The power supply start-up circuit may be configured, in a manner known per se, to start-up the associated equipment if a voltage VSTUP applied over start-up line to an input  12  goes above a start-up threshold VTHstup (e.g., around 12V). 
         [0020]    In one or more embodiments (for example, as shown in  FIG. 1 ), the power supply start-up circuit  10  may be activated by start-up stimuli provided, in a manner known per se (see e.g. US 2014/0056040 A1), for instance by an InfraRed (IR) or RadioFrequency (RF) remote control unit, not visible in the figures. Such start-up stimuli may be received by a start-up module such as, e.g., an IR/RF receiver  18  essentially acting as a switch adapted to transfer the power supply signal VL to the input  12  of the power supply start-up circuit  10 . Also, a start-up button may be used for that purpose e.g. to receive start-up stimuli applied by a human. 
         [0021]    In one or more embodiments, a logic unit  14  may be provided which may be activated by a power supply VSTUP, e.g. via a linear regulator  16  which may feed the logic unit  14  with a voltage VLU downscaled, for example, from a value of VSTUP of about 15V to a lower voltage, e.g., 3.3V. 
         [0022]    In one or more embodiments, the logic unit  14  may turn on during a start-up phase (e.g., by possibly being the first element to turn on during the start-up phase) in order to acknowledge the start-up stimuli with an embedded code in order to add robustness to the system. 
         [0023]    In one or more embodiments as considered herein, the voltage VSTUP may build up in hundreds of milliseconds, so that the voltage VLU will be stable and the logic unit  14  may turn on when VSTUP is still building up. 
         [0024]    In one or more embodiments, the logic unit  14  may rapidly take control of the system thus preventing the power supply start-up circuit  10  from starting up until the start-up stimuli received via the receiver  18  have been acknowledged. To that effect, in one or more embodiments, the logic unit  14  (which may be configured to send an enable signal ENAB to the power supply start-up circuit  10 ) may be activated (long) before the start-up value is reached by VSTUP so that the system may be disabled until acknowledgement takes place, e.g., by the code referred to in the foregoing. 
         [0025]    In one or more embodiments, a capacitor C 1  and a Zener diode Z may be coupled, for example, to the output of the start-up module (e.g., receiver)  18 , namely to the start-up line leading to the input  12  of the power supply start-up circuit  10  and feeding the logic unit  14 , e.g., via the regulator  16 . 
         [0026]    In one or more embodiments, the capacitor C 1  may play an active role during build-up of VSTUP. This may be regarded essentially as a ramp signal having a slope, which is a function of the capacitance value of C 1  (see e.g. US 2014/0056040 A1, already cited). In one or more embodiments, the logic unit  14  may turn on during the first build-up phase of the ramp, for example, VSTUP equal to 3.3 V or higher, when the corresponding voltage has just reached a value higher than the value permitting operation of the logic unit  14 . 
         [0027]    In one or more embodiments, the Zener diode Z may prevent the start-up line (VSTUP) from reaching (voltage) levels in excess of the limit values admitted for the circuits coupled therewith. 
         [0028]    In one or more embodiments, this arrangement may permit to exploit the logic unit  14  for storing the operating state of the system in order to meet a given operating target. 
         [0029]    One or more embodiments (see e.g.  FIGS. 2 to 4 ) may include a voltage detector  20  for providing the capability of assessing a faulty condition such as a power loss due, for example, to a mains M failure (blackout), so that the input line voltage VL will become unavailable and VSTUP will drop accordingly. 
         [0030]    The detector  20  will detect such an event and provide to the logic unit  14  a corresponding signal indicating that VSTUP is dropping below a safety (drop) threshold. 
         [0031]    Measures may be taken in order to ensure that, in the event of power failure, the logic unit  14  will be the last element to stop working after the power failure. For instance, in one or more embodiments, the threshold of the detector  20  may set high enough to permit the logic unit  14  to continue operating for a time interval during which the operating state may be stored, for example, in a non-volatile memory coupled with (optionally included in) the logic unit  14 . 
         [0032]    In one or more embodiments, the detector  20  and the logic unit  14  may thus co-operate in making the system capable of detecting and storing the information related to a faulty condition. 
         [0033]    An issue in automatically recovering the operating state may lie in that, after the power has been restored (e.g., with the input line voltage VL available again) the system may default to inactive until coded start-up stimuli are applied to the start-up module  18 , e.g., a result of a human intervention (e.g., IR or RF remote control, start-up button, and so on). 
         [0034]    One or more embodiments may rely on the observation that, for example due to parasitic effects, when the system is plugged in or the mains is restored after, e.g., a blackout or a voltage spike (e.g., a few volts) may appear on VSTUP for a short time, until the system reaches steady state operation. This per se undesired effect may turn out to be beneficial in permitting operational state recovery. 
         [0035]    To that effect, as exemplified in  FIGS. 3 and 4 , in one or more embodiments a circuit  22  may be coupled to the system which may become activated for a limited amount of time, e.g. when VL is building up. 
         [0036]    In one or more embodiments, the circuit  22  may be devised with the purpose of charging the capacitor C 1  under these conditions so that the voltage VSTUP satisfies the start-up condition, e.g. VSTUP&gt;VTHstup for the power supply start-up circuit. 
         [0037]      FIG. 4  shows a possible implementation of such a “mains activated” start-up circuit  22 , including an electronic switch, e.g. a transistor such as a FET  220 . In a possible embodiment, the conduction (e.g. source-drain) line of the transistor  220  may extend between the supply line (at voltage VL, e.g., powered from the mains M via a rectifier  24  and a filter capacitor CF) and ground. 
         [0038]    One of the conduction terminals (e.g. the source) of the transistor  220  may thus be connected to the line providing the voltage VSTUP in order to charge the capacitor C 1  via a resistor  222 . 
         [0039]    Operation (e.g. “turn-on” to the conductive state) of the transistor  220  may be driven by a pull-up circuit acting on the gate of the transistor  220  and including the series connection of a capacitor  224  and a resistor  226  between the input line (voltage VL) and the gate of the transistor  220 , and the parallel connection of a resistor  228  and a Zener diode  230  between the gate of the transistor  220  and ground. 
         [0040]    After a blackout the voltage VL will undergo a rapid transient, and the circuit  22  is arranged in order to respond to this transient by forcing VSTUP to a value satisfying the startup condition, e.g. VSTUP&gt;VTHstup, thus enabling the logic unit  14  to turn on the power supply start-up circuit  10 . 
         [0041]    In one or more embodiments, the logic unit  14  will be operative when the condition above is met, since the logic unit  14  will have been activated (long) in advance thus being in a position to decide if system turn-on should be enabled. Once the system is turned on, even if VSTUP is no longer affected by the circuit  22  (since the transient on VL has ended), the circuit  10  will maintain VSTUP at an operating value e.g. by means of an auxiliary circuit. One such circuit may be included in, e.g., a SMPS. 
         [0042]    In one or more embodiments as considered in the foregoing, the logic unit  14  may thus be able check the system state saved in its associated memory. 
         [0043]    If a “faulty” condition was stored (e.g. operation of the system interrupted due to a power failure) the logic unit  14  is now able to turn on the SMPS. 
         [0044]    Conversely, if no such condition was stored, for example because the system had been positively turned off before removing the voltage VL on the input line or because the system is plugged in the first time, the logic unit  14  will not enable the SMPS and the system will be maintained in a turn-off condition until positively activated, while VSTUP may dissipate, e.g., due to the activity of the logic unit  14 . 
         [0045]    Without prejudice to the underlying principles, the details and embodiments may vary, even significantly, with respect to what is illustrated herein purely by way of non-limiting example, without thereby departing from the extent of protection.