Abstract:
The disclosed embodiments relate to a system and method for reducing standby power consumption in an electronic device. There is provided an electronic device ( 10 ) comprising receiver circuitry ( 16 ), and power supply control circuitry ( 18 ) coupled in series with the receiver circuitry ( 16 ), wherein a ground connection of the receiver circuitry ( 16 ) is coupled to a voltage supply connection of the power supply control circuitry ( 18 ).

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to reducing the standby power consumption of an electronic device. More specifically, the present invention relates to a system for reducing power consumption of a power supply control circuitry. 
     BACKGROUND OF THE INVENTION 
     This section is intended to introduce the reader to various aspects of art, which may be related to various aspects of the present invention that are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
     Historically, electronic devices, such as consumer electronics equipment, were powered “on” or powered “off” by mechanical or electromechanical switches. For example, a television could be turned on or turned off with a mechanical knob. Turning the mechanical knob from the off position to the on position connected two electrical contacts that electrically coupled a power supply to the television&#39;s display system. 
     Beginning in approximately 1980, however, power control for electronic devices, especially consumer electronics equipment, began to move away from mechanical switches towards transistor-based switches. Transistor-based switches can be turned on by applying a current to the transistor. Because transistor-based switches do not require physical movement, they greatly expanded the power control options for electronic devices. For example, with a transistor based switch, a television could turn itself on or off when it received an electronic command signal (e.g., a remote control signal). This electronic signal could be generated by a remote controlled unit, such as an infrared remote control or by a switch mounted on the television itself. 
     Electronic devices employing transistor-based switches comprise a receiver that is configured to receive a signal from a remote device. Because the receiver does not know when a command signal may be received, the receiver is typically configured to remain “on” even when the electronic device appears to be “off.” This mode is referred to as “standby mode,” and the power drawn during standby mode (i.e., the power for the receiver) is referred to as “standby power.” 
     Reducing the standby power consumption of electronic devices is desirable. 
     SUMMARY OF THE INVENTION 
     Certain aspects commensurate in scope with the originally claimed invention are set forth below; however the invention may encompass a variety of aspects that may not be set forth below. 
     The disclosed embodiments relate to a system and method for reducing standby power consumption in an electronic device. There is provided an electronic device ( 10 ) comprising receiver circuitry ( 16 ), and power supply control circuitry ( 18 ) coupled in series with the receiver circuitry ( 16 ), wherein a ground connection of the receiver circuitry ( 16 ) is coupled to a voltage supply connection of the power supply control circuitry ( 18 ). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a block diagram of an electronic device configured to reduce standby power consumption in accordance with embodiments of the present invention; and 
         FIG. 2  is a schematic diagram of an electronic device configured to reduce standby power in accordance with embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     One or more specific embodiments of the present invention will be described below. Turning initially to  FIG. 1 , a block diagram of an electronic device configured to reduce standby power consumption in accordance with embodiments of the present invention is illustrated and generally designated by the reference numeral  10 . In one embodiment, the electronic device  10  is a television or other video display device. In alternate embodiments, the electronic device  10  can be a variety of consumer electronics including, but not limited to, video cassette recorders, digital video disk (“DVD”) players, digital video recorders, audio or video receivers, computers, cameras, and so forth. In still other embodiments, the electronic device  10  may comprise remote activation systems, such as those routinely found in automobiles or security systems. Further, those of ordinary skill in the art will appreciate that the above recited embodiments are merely exemplary and thus, not intended to be exclusive. 
     As illustrated in  FIG. 1 , the electronic device  10  may comprise a mains supply  12 . The mains supply  12  is configured to supply the operating power, for example 150 volts, for the electronic device  10 . The mains supply  12  may be coupled to a current limiting resistor  14  or another current source (not shown). As will be described in greater detail below, the resistor  14  may be selected to draw sufficient current from the mains supply  12  to supply a receiver  16  and a switch mode power supply (“SMPS”) controller  18 , with operating power. In one embodiment, the receiver  16  is configured to receive a “power-on” command and to generate an “enable” signal  17  to a SMPS controller  18 . In another embodiment, the receiver  16  may be configured to receive a command to switch from a first mode of operation to a second mode of operation. For example, the receiver  16  may receive a command to switch from a low power operating mode to a normal operating mode. 
     In one embodiment, the receiver  16  comprises an infrared (“IR”) receiver in combination with an on/off IR decoder for decoding the power-on signal received by the IR receiver. In an alternate embodiment (illustrated in  FIG. 2 ), the receiver  16  may comprise an IR receiver in series with the SMPS controller  18  with the on/off IR decoder arrayed in parallel with the IR receiver. In this configuration, the on/off decoder is configured to generate the enable signal  17 . In yet another embodiment, the receiver  16  is a radio frequency (“RF”) receiver and an RF decoder. Lastly, in still other alternate embodiments, the receiver  16  may be configured to receive and decode other suitable forms of wired or wireless signals. 
     As illustrated in  FIG. 1 , the SMPS controller  18  is coupled in series between the receiver  16  and ground. As such, those of ordinary skill in the art will appreciate that the ground connection (VSS) on the receiver  16  is coupled to the supply connection (VDD) on the SMPS controller  18 . Those of ordinary skill in the art will appreciate that this serial layout consumes less power than the conventional, parallel orientations, of the receiver  16  and the SMPS controller  18 . 
     As illustrated, the electronic device  10  may also include a voltage reservoir formed by a capacitor  20  and a diode  22  coupled between the receiver  16  and the SMPS controller  18 . When electronic device  10  is in the standby mode of operation, transformer  26  is in a non-energized state which reverse biases diode  22 , thus allowing the voltage node connecting the VSS terminal of receiver  16 , the VDD terminal of SMPS controller  18  and a terminal of capacitor  20  to be disconnected from the secondary winding of transformer  26 . Next, the SMPS controller  18  may also be coupled to an insulated gate bipolar transistor (“IGBT”)  24 . In one embodiment, when the SMPS controller  18  receives the enable signal  17 , the SMPS controller  18  is configured to enable the IGBT  24 . Once enabled, the IGBT  24  activates the transformer  26  and allows power to pass through a diode  28  to secondary side components  30 . Also when transformer  26  is activated, diode  22  is rendered conductive, thus establishing the VDD terminal of controller  18  at an operating potential established by the controller  18  and a secondary winding of transformer  26 . Once the secondary side components  30  have been powered, user commands may pass directly from the receiver  16  to the secondary side components (i.e., normal, non-standby or run-mode operation)  30 . In one embodiment, the secondary side comprises a microprocessor  122  configured to decode a variety of command signals besides the power-on command. 
       FIG. 2  is schematic diagram of an exemplary electronic device  50  configured to reduce standby power consumption in accordance with embodiments of the present invention. For simplicity, like reference numerals have been used to designate those features previously described in reference to  FIG. 1 . The electronic device  50  includes the mains supply  12 . In the illustrated embodiment, the mains supply  12  comprises a plurality of power supply lines, also referred to as the “mains”  52 , a plurality of switches  54  coupled to each of the mains  52 , and a bridge circuit  56  for rectifying the power transmitted through the mains  52 . The mains supply  12  may be coupled to a capacitor  58  for stabilizing the power generated by the mains supply  12 . In one embodiment, the capacitor  58  comprises a 100 microfarad capacitor. 
     The capacitor  58  may be coupled to the resistor  14  which was described above. In one embodiment, the resistor  14  comprises a 270 kilo Ohm (“kOhm”) resistor that generates a current of 1.2 milliamps. The resistor  14  may be coupled to a light emitting diode (“LED”)  60  that indicates current flow through the resistor  14 . 
     As illustrated, the LED  60  may be coupled to the receiver  16 , the diode  62 , and the capacitor  64 . As described above, the receiver  16  is configured to receive at least a “power-on” signal or command from an external device, such as a remote control. In one embodiment, the receiver  16  comprises an IR receiver, such as a TSOP 11 Series IR receiver module produced by Vishay Semiconductors or an 8-bit AVR microcontroller produced by Atmel Corporation. Those of ordinary skill in the art will appreciate that the diode  62  and the capacitor  64  may be configured to stabilize the voltage across the receiver  16 . In one embodiment, the capacitor  64  is a 470 nanofarad (“nF”) capacitor and the diode  62  is a 5V1 zener diode. 
     As illustrated in  FIG. 2 , the receiver  16  may be coupled to a capacitor  66  and a diode  68 . Those of ordinary skill in the art will appreciate that the capacitor  66  and the diode  68  are employed to clamp the voltage of the signal path via the capacitor  66  to a supply voltage (VDD) of an Infrared (“IR”) decoder  76 , because the receiver  16  and the IR decoder  76  are on different ground levels. The diode  68  may be coupled to a resistor  70 , a zener diode  72 , and a capacitor  74 . The resistor  70 , the diode  72 , and the capacitor  74  may be configured to provide the voltage VDD to the IR decoder  76 . In one embodiment, the resistor  70  is a 22 kOhm resistor, the zener diode  72  is a 3V3 diode, and the capacitor  74  is a 1 microfarad capacitor. In this embodiment, the resistor  70 , the diode  72 , and the capacitor  74  are configured to generate a voltage of 3.3 volts for the VDD input of the IR decoder  76 . 
     The IR decoder  76  may be configured to receive an input from the receiver  16  and to determine whether that input comprises a power-on command. During standby mode, a transistor  86  is turned “on” by IR decoder  76  through resistor  84 . If the output from the receiver  16  is a power-on command, the IR decoder  76  may switch “off” transistor  86  via resistor  84 . In addition, the IR decoder  76  may switch on a transistor  90  via a resistor  88 . As will be described in greater detail below, turning off the transistor  86  and enabling the transistor  90  may be part of a sequence of events that brings the electronic device  50  out of the standby mode. In one embodiment, the IR decoder  76  may also be coupled to a capacitor  78 , a capacitor  80 , and an oscillator  82 . In one embodiment, the IR decoder  76  is a PIC 12F629 low power microcontroller, the resistor  84  is a 10 kOhm resistor, and the resistor  88  is a 10 kOhm resistor. Moreover, the capacitor  78  may comprise a 100 picofarad (“pF”) capacitor, the capacitor  80  may comprise a 100 pF capacitor, and the oscillator  82  may comprise a low frequency (e.g., 100 kilohertz) oscillator. Further, while not illustrated in  FIG. 2 , those of ordinary skill in the art will appreciate that in alternate embodiments, the IR decoder  76  can either be integrated into the receiver  16  or arrayed in series between the receiver  16  and the SMPS controller  18 . 
     As stated above, when the IR decoder  76  receives a signal indicative of a power-on command, the IR decoder  76  may disable the transistor  86 . Once disabled, the transistor  86  allows normal run mode operation of the switch mode power supply by enabling the divider formed by resistors  96 , 98 . Resistors  96 , 98  are chosen to bias controller  18  pin  3  into an active region. As illustrated in  FIG. 2 , the voltage divider created by the resistor  96  and the resistor  98  is coupled to a primary voltage monitoring input pin (illustrated as “ISNS”) of the SMPS controller  18 , and the resistor  100  and the capacitor  102  are coupled to a primary current input reference pin (illustrated as “PIS”) of the SMPS controller  18  to stabilize foldback current limiting for higher mains voltages. Those of ordinary skill in the art will appreciate that applying voltages to each of these inputs enables the SMPS controller  18 . In one embodiment, the resistor  96  comprises a 100 mega Ohm resistor and the resistor  98  comprises a 105 kOhm resistor. In this configuration, the voltage divider formed by the resistor  96  and the resistor  98 , may generate 1.7 volts on the ISNS input of the SMPS controller  18 . In this embodiment, the resistor  100  may comprise a 1 mega Ohm resistor and the capacitor  102  may comprise a 1 nF capacitor. 
     As stated above, if the IR decoder  76  receives the signal indicative of a power-on command, the IR decoder  76  may enable the transistor  90 . Once enabled, the transistor  90  may “open up” a path for current through the resistor  94  to an optocoupler  92 . As described above, the IR decoder  76  may be configured to only decode the power-on command to reduce standby power consumption. Once powered on, however, the electronic device  10  may be configured to decode a variety of other suitable signals or commands. For this reason, once powered the optocoupler  92  serves as a pass-through for commands from the IR receiver  16  to another IR decoder  122  amongst the secondary side components. Unlike the IR decoder  76 , the IR decoder  122  is configured to decode signals in addition to the power-on command. For example, IR decoder  122  may be configured to receive channel change commands or volume adjustments for a television. In one embodiment, the resistor  94  may comprise a 10 kOhm resistor. IR decoder  122  may be any of a number of control microprocessors or special purpose control decoders generally available. 
     Returning to the SMPS controller  18 . The SMPS controller  18  may be any suitable form of power control microprocessor or microcontroller. In one embodiment, the SMPS controller  18  is a TDA 4605-3 Bipolar Integrated Circuit produced by Siemens Semiconductor. In another embodiment, the SMPS controller  18  is a FA1384X series power supply controller produced by Fuji Semiconductor. 
     The supply voltage input pin (illustrated as (“VDD”) of the SMPS controller  18  may be coupled to the voltage reservoir formed by the capacitor  20  and the diode  22 . In one embodiment, the capacitor  20  comprises a 47 microfarad capacitor. In addition, as illustrated in  FIG. 2 , the secondary voltage information pin (illustrated as “In”) and the oscillator feedback input (illustrated as “Zer”) of the SMPS controller  18  are coupled to resistors  106 ,  108 ,  110 ,  112 , a diode  114 , and capacitors  116  and  118 . Those of ordinary skill in the art will appreciate that the resistors  106 ,  108 ,  110 , the diode  114 , and the capacitors  116  and  118  may be configured to produce a regulating input on the secondary voltage information pin and input isolation feedback on the oscillation feedback pin. In one embodiment, the resistor  106  comprises a 10 kOhm resistor, the resistor  108  comprises a 4 kOhm resistor, the resistor  110  comprises a 2 kOhm resistor, the capacitor  116  comprises a 4 NF capacitor, and the capacitor  118  comprises a 1 microfarad capacitor. 
     As described above, a voltage applied to the ISNS input of the SMPS controller  18  may enable the SMPS controller  18 . The enabled SMPS controller  18  may generate a voltage/current from an output pin (illustrated as “out”) across a resistor  120 . This output voltage/current may enable the IGBT  24 . Once the IGBT  24  is enabled, the secondary side transformer  26  begins to draw power from the mains supply  12 . This power is passed across the transformer  26  via the diode  28  to the secondary side components  30 , which enables the electronic device to function normally. In one embodiment, the resistor  120  comprises a 47 ohm resistor. 
     While the invention may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.