Patent Publication Number: US-2021194366-A1

Title: Systems and methods for reducing power consumption of a power supply during a load&#39;s sleep mode

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Application Ser. No. 62/950,312 titled “SYSTEMS AND METHODS FOR REDUCING POWER CONSUMPTION DURING A POWER SUPPLY&#39;S SLEEP MODE,” filed on Dec. 19, 2019, which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     1. Field of Invention 
     The present disclosure relates generally to power supplies. More particularly, aspects of the present disclosure relate to systems and methods for reducing power consumption of a power supply during a sleep mode of the load. 
     2. Discussion of Related Art 
     The use of power devices, such as uninterruptible power supplies (UPS), to provide regulated, uninterrupted power for sensitive and/or critical loads, such as computer systems and other data processing systems, is known. Known uninterruptible power supplies include on-line UPS&#39;s, off-line UPS&#39;s, line interactive UPS&#39;s as well as others. On-line UPS&#39;s provide conditioned AC power as well as back-up AC power upon interruption of a primary source of AC power. Off-line UPS&#39;s typically do not provide conditioning of input AC power but do provide back-up AC power upon interruption of the primary AC power source. Line interactive UPS&#39;s are similar to off-line UPS&#39;s in that they switch to battery power when a blackout occurs but also typically include a multi-tap transformer for regulating the output voltage provided by the UPS. Logic Power Supply (LPS) systems typically provide required bias power to different subsystems (e.g., a Digital Signal Processor (DSP), microcontroller, control and communication systems, gate driver, etc.) of an Uninterruptible Power Supply (UPS). 
     SUMMARY 
     At least one aspect of the present disclosure is directed to a power circuit including an input configured to be coupled to an input source and to receive input power from the input source, a first output configured to provide LPS output power to a load, a Logic Power Supply (LPS) coupled to the input and configured to convert the input power into the LPS output power, the LPS configured to provide, in a first mode of operation, the LPS output power with a first voltage level in response to receiving an indication that the load is being powered by the LPS output power and configured to provide, in a second mode of operation, the LPS output power with a second voltage level in response to receiving an indication that the load is not being powered by the LPS output power, and a first switch configured to couple the LPS to the first output in the first mode of operation and to decouple the LPS from the first output in the second mode of operation. 
     In one embodiment, the power circuit includes a converter coupled to the LPS and configured to provide converter output power to a second output. In some embodiments, the converter is configured to receive the LPS output power from the LPS and convert the LPS output power into the converter output power. In certain embodiments, the converter is configured to receive intermediate power from the LPS and convert the intermediate power into the converter output power. In various embodiments, the second output is coupled to a controller configured to be powered by the converter output power and to provide at least one control signal indicating whether the load is being powered by the LPS output power. 
     In some embodiments, the load includes processing equipment coupled to the first output and configured to be powered by the LPS output power and to operate in at least an active state and a sleep state. In one embodiment, the second output is coupled to a controller configured to be powered by the converter output power and to provide at least one control signal indicating whether the load is being powered by the LPS output power, the controller being coupled to the processing equipment and configured to provide the at least one control signal such that the power circuit is operated in the first mode of operation while the processing equipment is operating in the active state and in the second mode of operation while the processing equipment is operating in the sleep state. 
     In certain embodiments, the second voltage level is a predetermined level selected to optimize efficiency of the power circuit while powering the controller during the second mode of operation. In one embodiment, the power circuit includes a feedback circuit configured to provide at least one feedback parameter to the LPS, the first and second voltage levels corresponding to the at least one feedback parameter of the LPS. In some embodiments, the feedback circuit includes a second switch configured to adjust the at least one feedback parameter to a first state in the first mode of operation and to a second state in the second mode of operation. In various embodiments, the first switch is included in the LPS. 
     Another aspect of the present disclosure is directed to a non-transitory computer-readable medium storing thereon sequences of computer-executable instructions for operating a power circuit. The sequences of computer-executable instructions include instructions that instruct at least one processor to operate the power circuit to receive input power from an input source at an input, operate a Logic Power Supply (LPS) to convert the input power into LPS output power provided to a first output, the LPS being configured to provide, in a first mode of operation, the LPS output power with a first voltage level in response to receiving an indication that a load coupled to the first output is being powered by the LPS output power and configured to provide, in a second mode of operation, the LPS output power with a second voltage level in response to receiving an indication that the load is not being powered by the LPS output power, control, in the first mode of operation, a first switch to couple the LPS to the first output, and control, in the second mode of operation, the first switch to decouple the LPS from the first output. 
     In one embodiment, the sequences of instructions include instructions that cause the at least one processor to operate the power circuit to operate a converter coupled to the LPS to provide converter output power. In some embodiments, operating the converter to provide the converter output power further includes operating the converter to convert the LPS output power provided by the LPS into the converter output power. In various embodiments, operating the converter to provide the converter output power further includes operating the converter to convert intermediate power provided by the LPS into the converter output power. In certain embodiments, the sequences of instructions include instructions that cause the at least one processor to operate the power circuit to receive at least one control signal indicating whether the load is being powered by the LPS output power, and provide the converter output power to a second output to power a controller coupled to the second output, the controller being configured to provide the at least one control signal. 
     In some embodiments, the sequences of instructions include instructions that cause the at least one processor to operate the power circuit to provide the LPS output power to the first output to power processing equipment coupled to the first output, the processing equipment being configured to operate in at least an active state and a sleep state. In one embodiment, the controller is coupled to the processing equipment and configured to provide the at least one control signal such that the power circuit is operated in the first mode of operation while the processing equipment is operating in the active state and in the second mode of operation while the processing equipment is operating in the sleep state. In various embodiments, the second voltage level is a predetermined level selected to optimize efficiency of the power circuit while powering the controller during the second mode of operation. 
     Another aspect of the present disclosure is directed to a method of assembling a power circuit. The method includes providing a Logic Power Supply (LPS) configured to be coupled to an input, the LPS being configured to provide, in a first mode of operation, output power with a first voltage level to an output in response to receiving an indication that a load coupled to the output is being powered by the output power and to provide, in a second mode of operation, output power with a second voltage level in response to receiving an indication that the load is not being powered by the output power, and coupling a switch between the LPS and the output, the switch being configured to couple the LPS to the output in the first mode of operation and to decouple the LPS from the output in the second mode of operation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various aspects of at least one embodiment are discussed below with reference to the accompanying figures, which are not intended to be drawn to scale. The figures are included to provide illustration and a further understanding of the various aspects and embodiments, and are incorporated in and constitute a part of this specification, but are not intended as a definition of the limits of the invention. In the figures, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every figure. In the figures: 
         FIG. 1  is a functional block diagram of a power supply system in accordance with aspects described herein; 
         FIG. 2  is a functional block diagram of a power supply system in accordance with aspects described herein; 
         FIG. 3  is a functional block diagram of a power supply system in accordance with aspects described herein; 
         FIG. 4  is a schematic diagram of a power supply system in accordance with aspects described herein; 
         FIG. 5  is a functional block diagram of a power supply system in accordance with aspects described herein; and 
         FIG. 6  is a functional block diagram of a UPS in accordance with aspects described herein. 
     
    
    
     DETAILED DESCRIPTION 
     Examples of the methods and systems discussed herein are not limited in application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings. The methods and systems are capable of implementation in other embodiments and of being practiced or of being carried out in various ways. Examples of specific implementations are provided herein for illustrative purposes only and are not intended to be limiting. In particular, acts, components, elements and features discussed in connection with any one or more examples are not intended to be excluded from a similar role in any other examples. 
     Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Any references to examples, embodiments, components, elements or acts of the systems and methods herein referred to in the singular may also embrace embodiments including a plurality, and any references in plural to any embodiment, component, element or act herein may also embrace embodiments including only a singularity. References in the singular or plural form are not intended to limit the presently disclosed systems or methods, their components, acts, or elements. The use herein of “including,” “comprising,” “having,” “containing,” “involving,” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. References to “or” may be construed as inclusive so that any terms described using “or” may indicate any of a single, more than one, and all of the described terms. In addition, in the event of inconsistent usages of terms between this document and documents incorporated herein by reference, the term usage in the incorporated references is supplementary to that of this document; for irreconcilable inconsistencies, the term usage in this document controls. 
     As discussed above, power supplies, such as uninterruptible power supplies (UPS), are oftentimes used to provide regulated, uninterrupted power to sensitive and/or critical loads. In some cases, a UPS may include a Logic Power Supply (LPS) system configured to provide bias power to processing equipment (e.g., a Digital Signal Processor (DSP), microcontroller, control and communication systems, gate driver, etc.) of the UPS. In certain examples, the LPS system may be configured to power a battery charger system, a temperature monitoring system, periodic data collector, etc. of the UPS. 
     In some examples, the LPS system is designed to operate at maximum efficiency (or maximum output) while fully supporting the processing equipment of the UPS. However, the processing equipment may be configured to operate in multiple modes or states of operation. For example, the processing equipment may operate in an active state (i.e., normal operation) and a sleep state (i.e., low power operation). As such, when the processing equipment is operating in the sleep state with low power consumption, the LPS system may operate inefficiently due to the reduced power consumption levels of the processing equipment. 
     In addition, electronic equipment (e.g., power supply systems, LPSs, etc.) may be subject to efficiency standards imposed by regulatory bodies, such as national and/or state energy commissions, environmental protection agencies, etc. As such, manufacturers of power supply systems (or LPSs) must provide products which comply with these standards and regulations. In some cases, when power supply systems or LPSs operate inefficiently due to reduced load power consumption of corresponding processing equipment, it can be difficult to meet such standards and regulations. 
     As such, an improved power supply system and method of operation are provided herein. In at least one embodiment, the power supply system includes an LPS configured to provide output power having a first voltage level when the load is being powered by the LPS and output power having a second voltage level when the load is not being powered by the LPS. In some examples, the LPS is selectively decoupled from the load when the load is not being powered by the LPS. In certain examples, by adjusting the voltage level of the output power provided by the LPS and selectively decoupling the LPS from the load, the LPS and the power supply system can operate with improved efficiency. 
       FIG. 1  is a block diagram of a power supply system  100 . In one example, the power supply system  100  includes an LPS assembly  102 , processing equipment  104 , and a controller  106 . As shown, the LPS assembly  102  includes an input  108 , an LPS  110 , a feedback and control unit  112 , a converter  114 , a first output  116 , and a second output  118 . As shown, the first output  116  is coupled to the processing equipment  104  and the second output  118  is coupled to the controller  106 . In addition, the processing equipment  104  is coupled via a control line  120  to the controller  106 . 
     In some examples, the controller  106  is configured to control or operate the processing equipment  104 . In certain examples, the controller  106  includes one or more general computing processors, specialized processors, or microcontrollers. The controller  106  may include specially-programmed, special-purpose hardware, for example, an application-specific integrated circuit (ASIC), or more generally designed hardware, such as a field programmable gate array (FPGA), or a general purpose processor. In some examples, the controller  106  is connected to one or more memory devices, such as a disk drive, memory, flash memory, embedded or on-chip memory, or other device for storing data. In certain examples, the controller  106  may be one or more controllers including one or more components such as one or more processors. 
     In one example, the input  108  is configured to receive input power (AC or DC) and provide the input power to the LPS  110 . The LPS  110  converts the input power into LPS output power having a DC voltage level (V LPS ) and provides the LPS output power to the processing equipment  104  via the first output  116 . In some examples, the LPS output power is also provided to the converter  114 . The converter  114  converts the LPS output power having the DC voltage level (V LPS ) into converter output power having a DC voltage level (V CON ). The converter output power is provided to the controller  106  via the second output  118 . 
     In some examples, the DC voltage level (V CON ) of the converter output power provided by the converter  114  is different (e.g., less) than the DC voltage level (V LPS ) of the LPS output power provided by the LPS  110 . For example, the DC voltage level (V CON ) of the converter output power may be a voltage level that is optimized or desired for powering the controller  106  (e.g., 3.3V, 5V, etc.). 
     In certain examples, the LPS output power is also provided to the feedback and control unit  112 . The feedback and control unit  112  includes feedback circuitry configured to provide one or more feedback parameters to the LPS  110 . The one or more feedback parameters may be processed or referenced by the LPS  110  to set the DC voltage level (V LPS ) of the LPS output power. As such, the feedback and control unit  112  may adjust the one or more feedback parameters provided to the LPS  110  to adjust or maintain the DC voltage level (V LPS ). In some examples, an adjustment to the DC voltage level (V LPS ) of the LPS output power may also provide an adjustment to the DC voltage level (V CON ) of the converter output power. 
     As described above, the LPS assembly  102  provides the LPS output power to the processing equipment  104  via the first output  116 . In some examples, the processing equipment  104  is configured to operate in at least two modes or states of operation, including an active state and a sleep state. In one example, the processing equipment  104  operates with complete functionality in the active state and operates with reduced functionality in the sleep state. For example, in the sleep state, the processing equipment may operate in a low power consumption mode, periodically “wake-up” to execute one or more functions, and return to the low power consumption mode. As such, when the processing equipment  104  is operating in the sleep state, the load on the LPS  110  is reduced. 
     In one example, when the load of the processing equipment  104  on the LPS  110  is reduced, the LPS  110  can become inefficient and lossy due to the reduced power consumption levels. In some examples, when the processing equipment  104  is configured to operate in the sleep state for an extended period of time, the reduced efficiency of the LPS  110  can increase the overall energy consumption of the power supply system  100 . In certain examples, the input  108  is configured to receive input DC power from a battery. In such examples, inefficient operation of the LPS  110  can lead to a shorter run time and/or deep battery discharge (i.e., over-discharge). 
       FIG. 2  is a block diagram of another power supply system  200 . In one example, the power supply system  200  includes an LPS assembly  202  that is similar to the LPS assembly  102  of  FIG. 1 , except the LPS assembly  202  includes a switch  204 . In some examples, the switch  204  is configured to selectively decouple the LPS  110  from the processing equipment  104  (or the first output  116 ). 
     As described above, the LPS  110  is operated to provide LPS output power to the processing equipment  104  via the first output  116 . Likewise, the converter  114  is operated to convert the LPS output power into converter output power and provide the converter output power to the controller  106  via the second output  118 . 
     In some examples, the processing equipment  104  is configured to operate in at least an active state and a sleep state. In certain examples, the controller  106  may control or operate the processing equipment  104  in each of the active and sleep states (via the control line  120 ). In other examples, the processing equipment  104  may send an indication of its operating state to the controller  106 . As such, the operating state of the processing equipment  104  is known by the controller  106 . 
     In one example, the LPS assembly  202  is configured to receive one or more control signals from the controller  106  based on the operating state of the processing equipment  104 . For example, the controller  106  may provide a first control signal  206  to operate (or control) the first switch  204  and a second control signal  208  to operate (or control) the feedback and control unit  112 . In one example, the first and second control signals  206 ,  208  are two different control signals; however, in other examples, the first and second control signals  206 ,  208  may be the same control signal (or control voltage). In certain examples, the first control signal  206  and/or the second control signal  208  can be provided to control circuitry configured to operate (or control) the switch  204  and/or the feedback and control unit  112 . 
     In some examples, the controller  106  is configured to control the LPS assembly  202  to operate in a first mode of operation and second mode of operation (via the one or more control signals). For example, when the processing equipment  104  is operating in the active state, the controller  106  may control the LPS assembly  202  to operate in the first mode of operation. Likewise, when the processing equipment  104  is operating in the sleep state, the controller  106  may control the LPS assembly  202  to operate in the second mode of operation. 
     In the first mode of operation, when the processing equipment  104  is operating in the active state, the switch  204  is controlled (or operated) by the first control signal  206  to couple the LPS  110  to the processing equipment  104  via the first output  116 . In addition, the feedback and control unit  112  is controlled (or adjusted) by the control signal  208  to provide a first feedback parameter to the LPS  110 . Based on the first feedback parameter, the LPS  110  is controlled (or operated) to provide the LPS output power having a first DC voltage level (V LPS_1 ). In one example, the first DC voltage level (V LPS_1 ) is selected or designed to provide optimal efficiency while the processing equipment  104  is operating in the active state. For example, the first DC voltage level (V LPS_1 ) may be selected such that the LPS assembly  202  (or the LPS  110 ) operates with maximum efficiency while supporting a load that includes the processing equipment  104  (in the active state) and the controller  106 . 
     In the second mode of operation, when the processing equipment  104  is operating in the sleep state, the switch  204  is controlled (or operated) by the first control signal  206  to decouple the LPS  110  from the first output  116 . In addition, the feedback and control unit  112  is controlled (or adjusted) by the control signal  208  to provide a second feedback parameter to the LPS  110 . Based on the second feedback parameter, the LPS  110  is controlled (or operated) to provide the LPS output power having a second DC voltage level (V LPs_2 ). In one example, the second DC voltage level (V LPS_2 ) is a predetermined level that is selected or designed to provide optimal efficiency while powering only the controller  106 . For example, the second DC voltage level (V LPS_2 ) may be selected such that the LPS assembly  202  (or the LPS  110 ) operates with improved efficiency while supporting only the controller  106 . 
     In some examples, the LPS assembly  202  operates with improved efficiency in the second mode of operation by reducing stress on the converter  114 . For example, the DC voltage level (V CON ) of the converter output power provided by the converter  114  is less than the first DC voltage level (V LPS_1 ) of the LPS output power provided by the LPS  110 . As such, in the second mode of operation of the LPS assembly  202 , when the LPS  110  is providing the LPS output power with the lower second DC voltage level (V LPS_2 ), stress on the converter  114  can be reduced. In certain examples, reducing stress on the converter  114  allows the converter  114  (and the LPS assembly  202 ) to operate with improved efficiency. In addition, by decoupling the LPS  110  from the first output  116 , power losses associated with storage capacitors in the processing equipment  104  can be eliminated during the second mode of operation. 
     As described above, the feedback and control unit  112  is controlled (or adjusted) by the control signal  208  to provide the first or second feedback parameter to the LPS  110  depending on the mode of operation of the LPS assembly  202 . In some examples, the feedback parameters correspond to an analog reference provided to the LPS  110 , such as a reference voltage or current. In other examples, the feedback parameters may correspond to digital signals or commands provided to the LPS  110 . In certain examples, additional components can be used in combination with the feedback and control unit  112  to provide different feedback parameters. 
     For example,  FIG. 3  is a block diagram of another power supply system  300 . In one example, the power supply system  300  includes an LPS assembly  302  that is similar to the LPS assembly  202  of  FIG. 2 , except the LPS assembly  302  includes an additional switch  304 . In some examples, the switch  304  is operated to adjust the feedback parameters provided by the feedback and control unit  112 . 
     As shown, the switch  304  may be controlled (or operated) by the control signal  208  provided by the controller  106 . For example, in the first mode of operation of the LPS assembly  302 , the control signal  208  may control the switch  304  to turn on (i.e., close), such that the feedback and control unit  112  provides the first feedback parameter to the LPS  110 . In one example, the first feedback parameter corresponds to at least one control loop gain parameter (e.g., feedback fraction, voltage reference, etc.) of the feedback and control unit  112 . Based on the at least one first feedback parameter, the LPS  110  operates to provide the LPS output power with the first DC voltage level (V LPS_1 ). 
     Similarly, in the second mode of operation of the LPS assembly  302 , the control signal  208  may control the switch  304  to turn off (i.e., open) such that the feedback and control unit  112  provides the second feedback parameter to the LPS  110 . In some examples, turning off the switch  304  causes one or more of the control loop gain parameters of the feedback and control unit  112  to change (or adjust). As such, the second feedback parameter may correspond to at least one of the adjusted control loop gain parameters. Based on the at least one second feedback parameter, the LPS  110  operates to provide the LPS output power with the second DC voltage level (V LPS_2 ). 
     It should be appreciated that the LPS assembly  302  may be configured to operate differently. For example, in the first mode of operation of the LPS assembly  302 , the control signal  208  may control the switch  304  to turn off (i.e., open). Likewise, in the second mode of operation of the LPS assembly  302 , the control signal  208  may control the switch  304  to turn on (i.e., close). 
       FIG. 4  is a schematic diagram of a power supply system  400 . In one example, the power supply system  400  corresponds to the power supply system  300  of  FIG. 3 . In some examples, the power supply system  400  includes an LPS assembly  402 , the processing equipment  104 , and the controller  106 . The LPS assembly  402  includes an input  408 , an LPS  410 , a feedback and control unit  412 , a converter  414 , a first output  416 , a second output  418 , and a switch  422 . As shown, the first output  416  is coupled to the processing equipment  104  and the second output  418  is coupled to the controller  106 . In addition, the processing equipment  104  is coupled via the control line  120  to the controller  106 . 
     In one example, the LPS  410  is configured as an offline-Flyback converter. As shown, the LPS  410  includes a rectifier (diodes  426   a - 426   d ), a first capacitor  428 , a switch  430 , a transformer  432 , a first diode  434 , and a second capacitor  436 . In some examples, the feedback and control unit  412  is included in the LPS  410 . In one example, the feedback and control unit  412  includes a switch  424 , a first resistor  438 , a second resistor  440 , a third resistor  442 , and a controller  444 . In certain examples, the resistors  438 - 442  form a feedback network (e.g., voltage divider) configured to provide a feedback voltage (V tbk ) to the controller  444 . Based on the feedback voltage (V tbk ), the controller  444  controls (or operates) the switch  430  such that the LPS  410  provides output power with desired voltage levels. 
     Similar to the LPS  110  of the LPS assembly  302 , the LPS  410  is operated to provide LPS output power to the processing equipment  104  via the first output  416 . Likewise, the converter  414  is operated to convert the LPS output power into converter output power and provide the converter output power to the controller  106  via the second output  418 . 
     In one example, the LPS assembly  402  is configured to receive one or more control signals from the controller  106  based on the operating state of the processing equipment  104 . For example, the controller  106  may provide a first control signal  446  to operate (or control) the switch  422  and a second control signal  448  to operate (or control) the switch  424 . In one example, the first and second control signals  446 ,  448  are two different control signals; however, in other examples, the first and second control signals  446 ,  448  may be the same control signal (or control voltage). In certain examples, the first control signal  446  and/or the second control signal  448  can be provided to control circuitry configured to operate (or control) the switch  422  and/or the switch  424 . 
     In some examples, the controller  106  is configured to control the LPS assembly  402  to operate in a first mode of operation and second mode of operation (via the one or more control signals). For example, when the processing equipment  104  is operating in the active state, the controller  106  may control the LPS assembly  402  to operate in the first mode of operation. Likewise, when the processing equipment  104  is operating in the sleep state, the controller  106  may control the LPS assembly  402  to operate in the second mode of operation. 
     In the first mode of operation, when the processing equipment  104  is operating in the active state, the switch  422  is controlled (or operated) by the first control signal  446  to couple the LPS  410  to the processing equipment  104  via the first output  416 . In addition, the switch  424  is turned on (i.e., closed) by the control signal  448 . As such, the third resistor  442  of the feedback network included in the feedback and control unit  412  is bypassed, and the feedback voltage (V tbk ) is set to a first state/level. Based on the feedback voltage (V tbk ), the switch  430  of the LPS  410  is controlled (or operated) by the controller  444  such that the LPS  410  provides the LPS output power having the first DC voltage level (V LPS_1 ). As described above, the first DC voltage level (V LPS_1 ) is selected or designed to provide optimal efficiency while the processing equipment  104  is operating in the active state. 
     In the second mode of operation, when the processing equipment  104  is operating in the sleep state, the switch  422  is controlled (or operated) by the first control signal  446  to decouple the LPS  410  from the first output  416 . In addition, the switch  424  is turned off (i.e., opened) by the control signal  448 . As such, the third resistor  442  of the feedback network is no longer bypassed, allowing the feedback voltage (V tbk ) to be set to a second state/level. Based on the feedback voltage (V tbk ), the switch  430  of the LPS  410  is controlled (or operated) by the controller  444  such that the LPS  410  provides the LPS output power having the second DC voltage level (V LPS_2 ). As described above, the second DC voltage level (V LPS_2 ) is selected or designed to provide optimal efficiency while powering only the controller  106 . 
     It should be appreciated that the LPS assembly  402  may be configured to operate differently. For example, in the first mode of operation of the LPS assembly  402 , the control signal  448  may control the switch  424  to turn off (i.e., open). Likewise, in the second mode of operation of the LPS assembly  402 , the control signal  448  may control the switch  424  to turn on (i.e., close). 
     In some examples, the LPS may have a different configuration. For example,  FIG. 5  is a block diagram of another power supply system  500 . In some examples, the power supply system  500  includes an LPS assembly  502  that is similar to the LPS assembly  302  of  FIG. 3 , except the LPS assembly  502  includes an LPS  510  having multiple outputs. 
     In one example, the LPS  510  includes a first LPS output  504  and a second LPS output  506 . In some examples, the first LPS output  504  provides LPS output power to the processing equipment  104  via the first output  116 . The converter  114  is operated to convert intermediate power provided by the second LPS output  506  into converter output power having a DC voltage level (V CON ). The converter output power is provided to the controller  106  via the second output  118 . 
     As described above, the LPS assembly  502  is configured to receive one or more control signals from the controller  106  based on the operating state of the processing equipment  104 . For example, the controller  106  may provide the first control signal  206  to operate (or control) the switch  204  and the second control signal  208  to operate (or control) the switch  304 . In one example, the first and second control signals  206 ,  208  are two different control signals; however, in other examples, the first and second control signals  206 ,  208  may be the same control signal (or control voltage). In certain examples, the first control signal  206  and/or the second control signal  208  can be provided to control circuitry configured to operate (or control) the switch  204  and/or the switch  304 . 
     In some examples, the controller  106  is configured to control the LPS assembly  502  to operate in a first mode of operation and second mode of operation (via the one or more control signals). For example, when the processing equipment  104  is operating in the active state, the controller  106  may control the LPS assembly  502  to operate in the first mode of operation. Likewise, when the processing equipment  104  is operating in the sleep state, the controller  106  may control the LPS assembly  502  to operate in the second mode of operation. 
     In the first mode of operation, when the processing equipment  104  is operating in the active state, the switch  204  is controlled (or operated) by the first control signal  206  to couple the first LPS output  504  to the processing equipment  104  via the first output  116 . In addition, the control signal  208  may control the switch  304  to turn on (i.e., close), such that the feedback and control unit  112  provides a first feedback parameter to the LPS  510 . Based on the first feedback parameter, the LPS  510  operates to provide the LPS output power with an output voltage level (V LPS ) via the first LPS output  504 . In addition, the LPS  510  operates to provide the intermediate power with a first intermediate voltage level (V INT_1 ) via the second LPS output  506 . 
     In one example, the output voltage level (V LPS ) of the LPS output power and the first intermediate voltage level (V INT_1 ) of the intermediate power are selected or designed to provide optimal efficiency while the processing equipment  104  is operating in the active state. For example, the output voltage level (V LPS ) and the first intermediate voltage level (V INT_1 ) may be selected such that the LPS assembly  502  (or the LPS  510 ) operates with maximum efficiency while supporting a load that includes the processing equipment  104  (in the active state) and the controller  106 . 
     In the second mode of operation, when the processing equipment  104  is operating in the sleep state, the switch  204  is controlled (or operated) by the first control signal  206  to decouple the first LPS output  504  of the LPS  510  from the first output  116 . In addition, the control signal  208  may control the switch  304  to turn off (i.e., open) such that the feedback and control unit  112  provides a second feedback parameter to the LPS  510 . Based on the second feedback parameter, the LPS  510  operates to provide the intermediate power with a second intermediate voltage level (V INT_2 ) via the second LPS output  506 . In some examples, the second intermediate voltage level (V INT_2 ) is less than the first intermediate voltage level (V INT_1 ). 
     In one example, the second intermediate voltage level (V INT_2 ) is selected or designed to provide optimal efficiency while powering the controller  106 . For example, the second intermediate voltage level (V INT_2 ) may be selected such that the LPS assembly  502  (or the LPS  510 ) operates with improved efficiency while supporting only the controller  106 . 
     As described above, LPS systems may be included in a UPS and configured to provide bias power to processing equipment (e.g., a Digital Signal Processor (DSP), microcontroller, control and communication systems, gate driver, etc.) of the UPS. 
       FIG. 6  is a block diagram of a UPS  600  in accordance with aspects described herein. In one example, the UPS  600  is configured as an online UPS. As shown, the UPS  600  includes an input  602 , a converter  604 , a DC bus  606 , an inverter  608 , an output  610 , a DC/DC converter  612 , an LPS assembly  614 , and a backup power interface  616 . In some examples, the backup power interface  616  is configured to receive backup DC power from a battery  618 . In certain examples, the UPS  600  may include the battery  618 ; however, in other examples the battery  618  may be external to the UPS  600 . 
     In addition, a controller  620  may be included in the UPS  600 . In one example, the controller  620  is coupled to and configured to operate the converter  604  and the inverter  608 . In certain examples, the controller  620  is external to the UPS  600 . In some examples, the controller  620  includes one or more general computing processors, specialized processors, or microcontrollers. The controller  620  may include specially-programmed, special-purpose hardware, for example, an application-specific integrated circuit (ASIC), or more generally designed hardware, such as a field programmable gate array (FPGA), or a general purpose processor. In some examples, the controller  620  is connected to one or more memory devices, such as a disk drive, memory, flash memory, embedded or on-chip memory, or other device for storing data. In certain examples, the controller  620  may be one or more controllers including one or more components such as one or more processors. 
     In one example, the UPS  600  is configured to receive input AC power provided by an electric utility at the input  602 . The converter  604  rectifies the input AC power to provide DC power to the DC bus  606 . In some examples, the converter  604  is configured as a Power Factor Correction converter circuit (PFC). The rectified DC power on the DC bus  606  may be provided to the DC/DC converter  612  to charge the battery  618  while mains (i.e., utility) power is available. In the absence of mains power, the DC/DC converter  612  is operated to discharge the battery  618  and provide DC power to the DC bus  606 . From the DC power on the DC bus  606 , the inverter  608  generates AC output power that is provided to a load coupled to the output  610  (not shown). Since power is provided to the DC bus  606  from either mains or the battery  618 , the output power of the UPS  600  is uninterrupted if the mains fails and the battery  618  is sufficiently charged. While not shown, the UPS  600  may also operate in a bypass mode where unconditioned power with basic protection is provided directly from an AC power source to the load via a bypass line. 
     In one example, the LPS assembly  614  corresponds to one of the LPS assemblies described herein (e.g.,  202 ,  302 ,  402 , or  502 ). As shown, the LPS assembly  614  may be coupled to the input  602  of the UPS  600  and configured to provide output power to one or more loads (e.g., the processing equipment  104  and the controller  106 ). As described above, the LPS assembly  614  may be operated in a first or second mode of operation depending on the state of the processing equipment  104 . In other examples, the LPS assembly  614  can be configured differently. For example, the input of the LPS assembly  614  may be coupled to the DC bus  606 . 
     While the LPS assembly  614  is shown as being included in an online UPS (e.g., UPS  600 ), it should be appreciated that the LPS assembly  614  may be included in different types of UPS configurations. For example, the LPS assembly  614  may be included in an offline UPS, DC-UPS, delta-conversion UPS, etc. 
     As described above, an improved power supply system and method of operation are provided herein. In at least one embodiment, the power supply system includes an LPS configured to provide output power having a first voltage level when the load is being powered by the LPS and output power having a second voltage level when the load is not being powered by the LPS. In some examples, the LPS is selectively decoupled from the load when the load is not being powered by the LPS. In certain examples, by adjusting the voltage level of the output power provided by the LPS and selectively decoupling the LPS from the load, the LPS and the power supply system can operate with improved efficiency. 
     Having thus described several aspects of at least one embodiment of this invention, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure and are intended to be within the spirit and scope of the invention. Accordingly, the foregoing description and drawings are by way of example only.