Patent Publication Number: US-2021194273-A1

Title: Redundant system and method for providing power to devices

Description:
BACKGROUND 
     Semiconductor fabrication facilities use a variety of devices and systems for processing semiconductor wafers in the fabrication of integrated circuits. Integrated circuit (IC) fabrication includes multiple processing procedures, performed by a variety of powered processing devices, which include etching, deposition, ion implantation, doping, bonding, etc., and in general forming insulating structures, conducting structures, trenches, vias, metal lines and components of passive and active electrical circuits, such as capacitors, resistors, inductors, transistors and antennas, on the semiconductor wafers. 
     Many of the processing devices use DC power. Since batches of wafers are typically processed under time-critical constraints using costly processing procedures, it is important that disruptions to the production process are minimized. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. 
         FIG. 1  illustrates a power supply system, according to an embodiment of the present disclosure; 
         FIG. 2  illustrates an enclosure of the power supply system of  FIG. 1 , according to an embodiment of the present disclosure; and 
         FIG. 3  illustrates a flowchart of a method for providing redundant power to an external device, according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. 
     Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly. 
     Wafers are often processed in batches, called lots. Dependent upon the processing procedure, the wafers may be processed in tanks or chambers, such as plasma processing chambers, chemical vapor deposition chambers, physical vapor deposition chambers, ion implantation chambers and photolithographic chambers. Wafers may also be cleaned, etched and rinsed in tanks or chambers. The processing chambers, tanks and other processing/containment systems, as well as other associated components, such as wafer transport/transfer systems and automated systems or devices such as robotic apparatuses, are typically powered by DC sources. 
     Typically, these powered components of the processing system have integrated DC power sources or integrated AC/DC conversion systems, and/or power systems that are combined with other control circuitry for controlling the integrated power systems and/or controlling the powered components during wafer processing. Due at least to the integration of DC power systems or AC/DC conversion systems with powered processing components and/or the integration with control systems, the DC power systems of conventional DC powered devices are susceptible of overheating, resulting in power failures or power inconsistencies, such as power spikes, thereby leading to disruption of production or production of substandard products. It would be advantageous to provide a system and method for addressing these concerns. 
       FIG. 1  illustrates a power supply system  100  according to an embodiment of the present disclosure. In the illustrated embodiment, the power supply system  100  includes a power supply module  102  having a first input  104  coupled to an AC power source  106  and a first output  108  coupled to an external device  110  via a power line  112 . In accordance with some embodiments of the present disclosure, AC power source  106  is a power transformer for the external device  110 . The power supply module  102  is configured to provide power to the external device  110  via the power line  112 . The illustrated power supply system  100  also includes a redundant power supply unit  114  having a second input  116  coupled to the AC power source  106  and a second output  118  coupled to the power line  112 . The power supply system  100  also includes a switching module  119 . The switching module  119  is configured to detect an electrical state of the power line  112 , and based upon the detected electrical state, either couple the redundant power supply unit  114  to the power line  112  for providing backup power (also referred to as redundant power) to the external device  110  or decouple the redundant supply unit  114  from the power line  112 . In accordance with disclosed embodiments, the system also includes an enclosure  120 , for example, a cabinet, a frame or a housing. Embodiments in accordance with the present disclosure are described below with reference to a cabinet  120 ; however embodiments of the present disclosure are not limited to enclosures that are a cabinet. The enclosure  120  is configured to support and in some embodiments enclose the power supply module  102 , the switching module  119  and the redundant power supply unit  114 . 
     According to an embodiment of the present disclosure, the power supply module  102  includes an AC/DC converter  122 . The AC/DC converter  122  is configured to convert a 220V AC signal received at the first input  104  from the AC power source  106  to a 24V DC signal as measured at the first output  108  of the power supply module  102 . However, the scope of the present disclosure covers AC/DC converters adapted to convert either a 110V AC signal or a 220V AC signal to 12V or 24V DC signals, as well as stepping the AC signal down to any DC voltage or DC current. The AC/DC converter  122  may include one or more of components, including components such as transformers, full waver rectifiers, smoothing capacitors, and voltage regulators. AC/DC converters are well known in the art and will not be discussed in more detail. 
     In another embodiment of the present disclosure, the power supply module  102  is a power supply board  102  configured for mounting the AC/DC converter  122 , as well as any circuitry used in conjunction with AC/DC converters. Power supply boards include circuit boards and may have metal lines, connectors, and other electrical components, such as resistors, capacitors, inductors and transistors, formed as integrated circuits and/or as discrete components. 
     In yet another embodiment according to the present disclosure, the power supply module  102  may optionally include the switching module  119 . For example, the power supply module  122  and the switching module  119  may be mounted to the power supply board  102 . 
       FIG. 2  illustrates a cabinet  120 , according to an embodiment of the present disclosure. The cabinet  120  includes a slot  202  for receiving the power supply module  102 . In one embodiment, the cabinet  120  is configured for receiving the power supply board  102 . In accordance with one embodiment of the present disclosure, the slot  202  and the power supply board  102  are configured with respective electrical contacts (not shown) and respective locking tabs (not shown) such that when the power supply board  102  is slid into the slot  202 , the respective tabs engage one another for locking the power supply board  102  in place, and the respective electrical contacts engage one another for electrically connecting the power supply board  102  with electrical components of the power supply system  100 , such as the power line  112  and/or the switching module  119 . 
     The power supply board  102  may also be easily removed from the power supply system  100  by disengaging the respective locking tabs and pulling the power supply board  102  out of the slot  202 . In one embodiment, an operator may, for example, push, pull and/or turn a locking tab for disengaging and/or engaging the tabs with one another. However, the scope of the present disclosure also covers securing the power supply board  102  in place in the slot  202  via screws, clamps, bars, or by other mechanically removable bindings. 
     Referring again to  FIG. 1 , and in accordance with another embodiment of the present disclosure, the redundant power supply unit  114  includes a redundant power supply module  124  coupled between the second input  116  of the redundant power supply unit  114  and the second output  118  of the redundant power supply unit  114 . In accordance with embodiments of the present disclosure, redundant power supply unit  114  further includes a backup power source  126  coupled to the second output  118  of the redundant power supply unit  114 . In one embodiment, the redundant power supply module  124  is configured to charge the backup power source  126 . For example, in one embodiment the redundant power supply module  124  is configured to charge the backup power source  126  when the redundant power supply unit  114  is decoupled, by the switching module  119 , from the power line  112 . In accordance with embodiments of the present disclosure, redundant power supply unit is electrically connected and powered by a power transformer for the external device  110 . 
     According to an embodiment of the present disclosure, the redundant power supply module  124  includes an AC/DC converter  125  (also referred to as a redundant AC/DC converter) configured to convert the 220V AC signal received at the second input  116  of the redundant supply unit  114  to a 24V DC signal as measured at the second output  118  of the redundant power supply unit  114 . The AC/DC converter  125  may be identical to the AC/DC converter  122  of the power supply module  102  or it may be different. The scope of the present disclosure covers AC/DC converters adapted to convert either a 110V AC signal or a 220V AC signal to 12V or 24V DC signals, as well as stepping the AC signal down to any DC voltage or DC current. The AC/DC converter  125  may include one or more of components, including components such as transformers, full waver rectifiers, smoothing capacitors, and voltage regulators. 
     According to another embodiment of the present disclosure, the redundant power supply module  124  is a power supply board  124  (also referred to as a redundant power supply board  124 ) configured for mounting the redundant AC/DC converter  125 , as well as any circuitry used in conjunction with AC/DC converters. Referring again to  FIG. 2 , the cabinet  120  includes a slot  204  for receiving the redundant power supply module  124 . In one embodiment, the cabinet  120  is configured for receiving the redundant power supply board  124 . The slot  204  and the redundant power supply board  124  are configured with respective electrical contacts (not shown) and respective locking tabs (not shown) such that when the redundant power supply board  124  is slid into the slot  204 , the respective tabs engage one another for locking the redundant power supply board  124  in place, and the respective electrical contacts engage one another for electrically connecting the redundant power supply board  124  with electrical components of the system  100 , such as the backup power source  126  and/or the switching module  119 . 
     The redundant power supply board  124  may also be easily removed from the system  100  by disengaging the respective locking tabs and pulling the redundant power supply board  124  out of the slot  204 . In one embodiment, an operator may, for example, push, pull and/or turn a locking tab for disengaging and/or engaging the tabs with one another. However, the scope of the present disclosure also covers securing the redundant power supply board  124  in place in the slot  204  via screws, clamps, bars, or by other mechanically removable bindings. 
     In yet another embodiment of the present disclosure, the redundant power supply unit  114  is configured as a redundant power supply board to which the redundant power supply module  124 , the power backup source  126 , and optionally the switching module  119  are electrically mounted. In this embodiment, the slot  204  of the cabinet  120  is configured for receiving the redundant power supply board. The slot  204  and the redundant power supply board may be configured with respective electrical contacts (not shown) and respective locking tabs (not shown) such that when the redundant power supply board is slid into the slot  204 , the respective tabs engage one another for locking the redundant power supply board in place, and the respective electrical contacts engage one another for electrical connecting the redundant power supply board with other electrical components of the system  100 , such as the switching module  119  or the power line  112 . 
     Referring again to  FIG. 1 , and in a further embodiment of the present disclosure, the backup power source  126  has a first node  130  and a second node  132 . The first node  130  of the backup power source  126  is coupled to the second output  118  of the redundant power supply unit  114  and the second node  132  of the backup power source  126  is coupled to ground (e.g., a ground for the system  100 ). 
     In one embodiment of the present disclosure, the backup power source  126  is a power capacitor  126 . The power capacitor  126  may be any capacitor configured to 25 volts or greater. In another embodiment of the present disclosure, the backup power source  126  is a battery configured to 25 volts or greater. In one embodiment, a first plate (not shown) of the power capacitor  126  (or battery) is coupled to the first node  130 , and a second plate (not shown) of the power capacitor  126  (or battery) is coupled to the second node  132  (i.e., coupled to ground). Embodiments in accordance with the present disclosure are not limited to power capacitors and batteries that store 25 volts or greater. Power capacitors or batteries that are not capable of storing 25 volts or more are included in embodiments described herein, e.g., power capacitors or batteries that are only able to store less than 25 volts. 
     The switching module  119  is configured to detect the electrical state of the power line  112  and couple/decouple the redundant power supply unit  114  to/from the power line  112  based upon the detected electrical state. According to one embodiment of the present disclosure, the electrical state is a voltage on the power line  112 , a current on the power line  112  and/or power on the power line  112 . The electrical state may also include a resistance of the power line  112  for determining, for example, if the power line  112  has been shorted to ground or if the power line  112  is an open circuit. 
     In one embodiment, the switching module  119  includes a switch  121  configured to close, or remain closed, when the switching module  119  detects that the voltage on the power line  112  is less than a predefined minimum voltage threshold or greater than a predefined maximum voltage threshold, or the current on the power line  112  is less than a predefined minimum current threshold or greater than a predefined maximum current threshold, and/or the power on the power line  112  (e.g., power being delivered over the power line  112  to the external device  110 ) is less than a predefined minimum power threshold or greater than a predefined maximum power threshold. When one of the above-defined electrical states of the power line  112  is detected, the power supply module  102  is providing the external device  110  with either insufficient power, voltage and/or current or too much power, voltage and/or current for proper operation of the external device  110 . When the switch  121  is closed, the power backup source  126  is connected to the external device  110  via the power line  112 , and the power backup source  126  provides sufficient power (also referred to as redundant power) and/or voltage and/or current to the external device  110 . The power supply system  100  thus provides the external device  110  an uninterrupted supply of in-spec operating power, voltage and/or current, independent upon whether the power supply module  102  is failing, has failed, or is operating in a substandard manner. 
     Although not illustrated, the switching module  119  may include integrated circuits and/or discrete components, such as resistors, capacitors and inductors configured for measuring voltages, currents and/or power on the power line  112 . Circuits for measuring voltages, currents and power on electrical lines are well known in the art and will not be discussed in more detail. 
     In another embodiment of the present disclosure, the switch  121  is configured to open or remain open when the switching module  119  detects that the voltage on the power line  112  is greater than or equal to the predefined minimum voltage threshold and less than or equal to the predefined maximum voltage threshold, the current on the power line  112  is greater than or equal to the predefined minimum current threshold and less than or equal to the predefined maximum current threshold, and/or the power on the power line  112  is greater than or equal to the predefined minimum power threshold and less than or equal to the predefined maximum power threshold. The external device  110  is disconnected from the backup power source  126  when the switch  121  is in an open state. By disconnecting the backup power source  126  from the external device  110 , the backup power source  126  can be effectively recharged by the redundant power supply module  124 . 
     In another embodiment of the present disclosure, the enclosure  120  is a cabinet configured as a heat sink for the power supply module  102 , the redundant power supply unit  114  and/or the switching module  119 . Referring again to  FIG. 2 , and according to an embodiment of the present disclosure, cabinet  120  includes a top portion  206 , a side portion  208  and a bottom portion  210 , or any combination of the top portion  206 , side portion  208  and bottom portion  210 . According to one embodiment, the top portion  206 , the side portion  208  and/or the bottom portion  210 , or any combination of the top portion  206 , the side portion  208  and the bottom portion  210 , are configured as heat sinks for the power supply module  102 , the redundant power supply unit  114  and/or the switching module  119 . For example, any of the top, side and bottom portions  206 ,  208 ,  210  of cabinet  120  may be formed of a metal, such as a metal having a relatively high thermal conductivity, may have corrugated surfaces and/or may have slotted openings for conducting heat from the interior of the cabinet  120  to outside the cabinet  120  and to the environment around the cabinet. In accordance with other embodiments, enclosure  120  can be a frame or housing which does not include a top, side and/or bottom portion. In accordance with such alternative embodiments, enclosure  120  is open at one or more of its top, side and/or bottom sides. In such alternative embodiments, enclosure  120  includes thermally conductive structures, such as thermally conductive fins, designed to dissipate thermal energy to an environment around such thermally conductive structure. The enclosure  120  includes a thermal energy pathway along which thermal energy from the power supply module  102 , redundant power supply unit  114  and/or the switching module  119  is transmitted to the thermally conductive structures. 
     Furthermore, although not illustrated, heat conducting strips may connect portions of the top, side and/or bottom portions  206 ,  208 ,  210  of the cabinet  120  with portions of the power supply module  102 , the redundant power supply unit  114  and/or the switching module  119 , such as portions of the power supply board  102  and the redundant power supply board  114 . Alternatively, the power supply board  102 , the redundant power supply board  114 , and the slots  202 ,  204  can be configured such that contact between the boards  102 ,  114  (e.g., edges (not shown) of the boards  102 ,  114 ) and the top, side, and/or bottom portions  206 ,  208 ,  210  of the cabinet  120  occurs when the boards  102 ,  114  are inserted into the respective slots  202 ,  204 , thereby enabling heat transfer from the boards  102 ,  114  to the top, side and/or bottom portions  206 ,  208 ,  210  of the cabinet  120 . 
     According to another embodiment of the present disclosure, the power supply system  100  may include an electrical monitoring device  134  having a display  136 , as illustrated by  FIGS. 1 and 2 . The electrical monitoring device  134  may be attached to the cabinet  120 , for example attached to a side portion  208  of the cabinet such that the electrical monitoring device  134  is not contained within the cabinet  120 . The electrical monitoring device  134  may be coupled to the power supply module  102  and optionally to the redundant power supply unit  114 . The electrical monitoring device  134  is configured to detect the electrical state of the power supply module  102  and the redundant power supply unit  114  and display the electrical states of the power supply module  102  and the redundant power supply unit  114  on the display  136 . For example, the electrical states of the power supply module  102  and the redundant power supply unit  114  may include any interior voltage, current or power measured with respect to any components or lines connecting components that compose the power supply module  102  and the redundant power supply unit  114 , such as transformers, rectifies, capacitors, voltage regulators, and optionally the backup power source  126  and/or switching module  119 . Although not illustrated, the electrical monitoring device  134  may include integrated circuits and/or discrete components, such as resistors, capacitors, inductors configured for measuring voltages, currents and/or power of circuit components of electrical systems. 
     In addition to detecting the electrical state of the power supply module  102  and optionally the redundant power supply unit  114 , the electrical monitoring device  134  may be configured to generate alert messages for display by the display  136  and/or audio alert messages sent to speakers (not shown), based upon the detected electrical state. Thus, a system operator may be alerted that a power supply module is performing insufficiently, is failing or has failed. The operator may then replace the faulty power supply module, e.g., the power supply module  102 , with a new power supply module. The failure or insufficient performance of a power supply module, as well as the replacement thereof, may be performed without any interruption of power to the external device  110 , since the power will be supplied to the external device  110  by the backup power source  126  of the redundant power supply unit  114  until a new power supply module is installed and providing adequate (i.e., in-spec) power to the external device  110  via the power line  112  as detected by the switching module  119 . 
     Alternatively, or in addition, the electrical monitoring device  134  may be coupled to the power line  112  and/or the switching module  119 . In this embodiment, the electrical monitoring device  134  is additionally configured to detect the electrical state of the power line  112  and/or the switching module  119  and display the electrical state(s) of the power line  112  and/or the switching module  119  on the display  136 . For example, the electrical state of the power line  112  may be a voltage on the power line  112 , a current on the power line  112  and/or power on the power line  112 . The electrical state may also include a resistance of the power line  112  for determining, for example, if the power line  112  has been shorted to ground or if the power line  112  is an open circuit. In addition to detecting the electrical state of the power line  112  and/or the switching module  119  and displaying the electrical state on the display  136 , the electrical state monitoring device  134  may be configured to generate alert messages for display on the display  136 , or audio alert messages sent to speakers (not shown), based upon the detected electrical state of the power line  112  and/or the switching module  119 . 
     In another embodiment of the present disclosure, and as illustrated by  FIG. 1 , the cabinet  120  is configured to be physically separated from the external device  110 . For example, in the illustrated embodiment, the minimum distance between the cabinet  120  and the external device is indicated by a distance d. By containing components of one or more of the power supply module  102  and/or redundant power supply unit  114  in a cabinet  120  spaced from the external device  110  being powered, thermal energy generated by components of one or more of the power supply module  102  and optionally the redundant power supply unit  114  is readily removed from such components and more readily dissipated to the environment. Doing so reduces the risk of any of the components enclosed by the cabinet  120  will be exposed to temperatures that will result in overheating of the components which could result in failure of such components. The distance d will depend upon the type of external device  110  and the amount of thermal energy generated by operation of the external device  110  and the components of power supply module  102  and optionally the redundant power supply unit  114 , as well as the ambient temperature of the surrounding environment in which the cabinet  120  is placed, and the power being generated by the power supply board  102 , the redundant power supply unit  114  and the switching module  119  of the cabinet  120 . Examples of suitable distances d vary over a wide range, e.g., over 1 meter, over 2 meters, over 3 meters or over 5 meters. Embodiments of the present disclosure are not limited to the foregoing values for d. D can be a distance that falls outside the foregoing ranges. 
     In one embodiment according to the present disclosure, the external device  110  is a powered component of a semiconductor processing system, such as a deposition chamber, an ion bombardment chamber or an etching chamber/tank. The semiconductor processing system may be used in the fabrication of integrated circuits on semiconductor wafers. However, embodiments of the present disclosure can be implemented in any DC powered system in which the minimization of the risk of power failure, the delivery of uninterrupted power, and the control of heat dissipation is important. 
     In yet another embodiment according to the present disclosure, and as illustrated by  FIG. 1 , the system  100  includes a plurality of power supply modules, including the optional power supply modules  102 A,  102 B. Although  FIG. 1  illustrates three power supply modules  102 ,  102 A,  102 B, the scope of the present disclosure includes more than 3 power supply modules. Each of the power supply module  102 A,  102 B has a first input  104 A,  104 B coupled to the AC power source  106  and a first output  108 A,  108 B coupled to a corresponding device  110 A,  110 B via a corresponding power line  112 A,  112 B. Each power supply module  102 A,  102 B is configured to provide power to the corresponding device  110 A,  110 B via the corresponding power line  112 A,  112 B. The system  100  may also include a plurality of switching modules, including the optional switching modules  119 A,  119 B. Each switching module  119 A,  119 B is coupled to a corresponding power line  112 A,  112 B. The second output  118  of the redundant power supply unit  114  is coupled to each of the switching module  119 A,  119 B. Each of the switching module  119 A,  119 B is configured to detect an electrical state of the corresponding power line  112 A,  112 B and connect the redundant power supply unit  114  to the corresponding power line  112 A,  112 B for providing redundant power (i.e., backup power) to the corresponding external device  110 A,  110 B based upon the detected electrical state. The cabinet  120  is configured to enclose the plurality of power supply modules  102 ,  102 A,  102 B, the plurality of corresponding switching modules  119 ,  119 A,  119 B and the redundant power supply unit  114 . As illustrated by  FIG. 2 , the slots  202 A,  202 B may be configured to receive the power supply modules  102 A,  102 B, respectively. 
     Although  FIGS. 1 and 2  illustrate only one electrical monitoring device  134 , the scope of the present disclosure includes embodiments having a plurality of electrical monitoring devices  134 , where each monitoring device  134  is coupled to a corresponding power supply  102 , and one monitoring device  134  may be coupled to the redundant power supply unit  114 . Thus, if the system includes n power device modules  102  and one redundant power supply unit  114 , then the system may include n+1 electrical monitoring devices  134 . 
       FIG. 3  illustrates a flowchart of a method  300  for providing uninterrupted power to an external device, according to an embodiment of the present disclosure. In step  302 , AC power is received from an external AC power source. For example, a power supply module  102  and a redundant power supply unit  114  may receive an AC signal, such as a 220V AC signal from an external AC power source  106 . 
     In step  304 , the received AC power is converted to DC power. For example, both the power supply module  102  and the redundant power supply unit  114  may convert a received AC signal, such as a 220V AC signal, to a DC signal, such as a 24V DC signal. However, the scope of the present disclosure covers converting any AC signal to any DC signal. 
     In step  306 , an external device is powered with the DC power. For example, the power supply module may provide DC power for powering the external device over a power line. 
     In step  308 , a backup power source is charged with the DC power. For example, the redundant power supply unit charges the backup power source with the DC power. In one embodiment according to the present disclosure, the backup power source is charged by the redundant power supply unit while the backup power source is uncoupled from the power line. 
     In step  310 , DC power is detected on the power line. For example, a switching module includes circuitry configured to detect power, voltage and/or current on the power line. 
     In step  312 , the backup power source is coupled to the power line for powering the external device based on the detected DC power. For example, the switching module may include a switch configured to close for coupling the backup power source to the power line for powering the external device based on the detected DC power. In one embodiment, the backup power source is coupled to the power line when the detected DC power is below a predefined minimum DC power threshold or above a predefined maximum DC power threshold. In another embodiment, the backup power source may be decoupled from the power line when the detected DC power is greater than or equal to the predefined minimum DC power threshold and less than or equal to the predefined maximum DC power threshold. In yet another embodiment according to the present disclosure, the backup power source is a power capacitor or a battery. In one embodiment, the power capacitor or the battery is configured to be charged to at least 25V. 
     The present disclosure provides a power system and method for providing uninterrupted power to an external device(s), as well as reducing the risk of a power failure by the power system due to overheating of the power system by providing a heat sink for the power system and/or physically separating the power system from external devices powered by the power system so as to control the dissipation of heat produced by the power system and mitigate the effect of heat generated by the external devices on the power system. In the event of a power failure or substandard output, the power system and method of the present disclosure provides uninterrupted delivery of backup power to the external devices until the subsystem(s) providing the failed power can be replaced. The power system and method of the present disclosure provides uninterrupted delivery of power at the time of power failure and during the replacement of the failed power supply subsystem with a new power supply subsystem. Furthermore, the power system and method of the present disclosure provides for monitoring components of the system and for efficient replacement of faulty components detected by the monitoring. 
     In one embodiment, a power supply system includes a power supply module having a first input coupled to an AC power source and a first output coupled to an external device via a power line. The power supply module is configured to provide power to the external device via the power line. The power supply system may further include a switching module coupled to the power line and a redundant power supply unit having a second input coupled to the AC power source and a second output coupled to the switching module. The switching module is configured to detect an electrical state of the power line and connect the redundant power supply unit to the power line for providing redundant power to the external device based upon the detected electrical state. The power supply system may further include a cabinet. The cabinet is configured to enclose the power supply module, the switching module and the redundant power supply unit. 
     In another embodiment, a power supply system includes a plurality of power supply modules. Each power supply module has a first input coupled to an AC power source and a first output coupled to a corresponding external device via a corresponding power line. Each power supply module is configured to provide power to the corresponding external device via the corresponding power line. The power supply system may further include a plurality of corresponding switching modules. Each corresponding switching module is coupled to the corresponding power line. The power supply system may further include a redundant power supply unit having a second input coupled to the AC power source and a second output coupled to each corresponding switching module. Each corresponding switching module is configured to detect an electrical state of the corresponding power line and connect the redundant power supply unit to the corresponding power line for providing redundant power to the corresponding external device based upon the detected electrical state. The power supply system may further include a cabinet. The cabinet is configured to enclose the plurality of power supply modules, the plurality of corresponding switching modules and the redundant power supply unit. 
     In a further embodiment, a method for providing uninterrupted power to an external device includes receiving AC power from an external AC power source, converting the received AC power to DC power, powering the external device with the DC power via a power line, charging a backup power source with the DC power while the backup power source is uncoupled from the power line, detecting the DC power on the power line, and coupling the backup power source to the power line for powering the external device based on the detected DC power. 
     The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. 
     Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.