EMI Filters for UPS
EMI stands for “Electromagnetic Interference” and is also known as electrical noise. Thus, an EMI filter is used for noise suppression and there is at least one EMI filter in all modern electronics. EMI itself can be created within the wiring of a circuit or it can be radiated through the air (referred to as “RFI.”) EMI shielding and filtering is required by government standards. EMI noise interferes with a circuit’s ability to operate properly. This is especially true with portable devices, since they are designed to save power, which typically means lower signal voltages. With lower voltage, there is less head room for noise to ride without becoming an unintended part of the signal. Devices with poor EMI prevention can interfere with air plane flight frequencies, causing static in the same radio band that is used to by traffic control towers to direct pilots landing and taking off. This is why all electronic devices are turned off before take-off and landing.
One of the biggest sources of EMI is in the generation of parasitic noise, which is created by the circuit itself. Unintended capacitance facilitates the transfer of high frequency, random noise into a circuit or other parts of a system. All AC/DC switch mode power supplies have EMI filters that allow them to comply with standards. Design engineers from all industries report that one of the more difficult tasks is achieving EMI safety compliance and that EMI is a significant factor in new product development, even at the system level. At the system level, it can be very difficult to find the source of the EMI noise and eradicate or prevent it.
Switch Mode Chargers for UPS
A switch mode (SMBC) battery charger converts alternating current (AC) to Direct Current (DC). Switch mode chargers are faster, smaller, lighter, and more efficient than equivalent linear battery chargers. Designing a battery charger with switching converter topologies to charge battery packs has considerations with regard to the required charge-current level, AC adapter voltage level range, the expected ambient temperature range, and the desired converter switching frequency. The buck converter topology is most often used for switch mode chargers in either synchronous or non-synchronous modes.
Switch-mode battery chargers can be quite sophisticated. They can be programmable and come with multiple monitoring and safety features that are especially ideal for potentially dangerous battery chemistries. Some features of SMBCs include efficient PWM control, highly accurate charge current and voltage regulation, adapter current regulation, charge preconditioning, charge status monitoring, output for LED indication, battery temperature sensing, sleep mode for energy efficiency once the battery is fully charged, and more.
Switch-mode charging reduces power use over a wide range of voltages, but can require more PCB board space and is more complicated than linear chargers. Linear chargers are small and the lack of switching means there is less noise liable to be introduced into the surrounding circuitry. However, linear chargers are less power efficient than switch-mode chargers. Pulse type chargers are also small and efficient but require a current-limited AC adapter.
Analog-to-Digital Converters for UPS
An Analog-to-Digital Converter (ADC or A/D converter) measures the magnitude of an input analog signal and converts it to a digital number that is proportional to the magnitude of the voltage or current. An ADC often converts signals collected from the real-world to digital signals for processing. One of the more important specifications of an ADC is the resolution that it offers – the more bits, the higher the resolution. A higher resolution yields a more accurate approximation of the analog input.
Temperature Sensors for UPS
A temperature sensor is a device that measures cold or heat as a temperature or temperature gradient. Many applications require some implementation of temperature sensing and measurement. For motors, the operating temperature inside the case is monitored by the processor and set to alarm or shut down at temperatures higher than the normal operating temperature of the motor. If a motor runs at too high of a temperature for too long, it can reduce the life of the motor. Operating temperature is an indication of the general operating health of the motor. Higher temperatures inside the motor case can mean too high of a load is placed on the motor, since as load increases, motor current consumption increases to meet the load requirements.
Rechargeable Batteries for UPS
Batteries are a portable, wireless means of storing energy via the use of self-contained chemical cells. They can be for one-time use and discarded, or recharged and reused. In essence, a battery is an energy storage device, but can only store and release electricity as direct current. Direct current is a flat line at a given amplitude (until it declines as it is exhausted), versus alternating current, which is a sinusoidal wave.
Processors for UPS
The term "processor" refers to an electronic device that performs computational functions and carries out the instructions of a stored program. Other terms for processor are microprocessor, central processing unit, and digital signal processor. Essentially, the processor refers to "the brains of a computer."
Drivers for UPS
It is a common misconception that most power MOSFETs or IGBTs can be driven directly from a logic circuit or microcontroller. The reality is that most of these high-power transistors require current and voltage levels that far exceed the capacity of control electronics. Essentially, a gate driver is a power amplifier which serves as an interface between a low-power PWM signal and the gate of an IGBT/MOSFET transistor.
Displays for UPS
The most common and ubiquitous of display devices is the LCD. LCD means "liquid crystal display." It is an electronically driven flat panel screen that orients liquid crystals within the panel in a direction that blocks or transmits light coming from behind the panel. LCDs are a low cost, energy efficient visual display that can be controlled in segments or as individual pixels, in shades of black and gray or in full color. LCDs have most commonly replaced bulky cathode ray tubes in televisions and computers and are available in all sizes. Liquid crystals were first discovered in 1888, but were first put into common use in the early 1970s as electronic digital-display watches.
USB Transceivers for UPS
USB is a standard connection interface between computers and digital devices. A USB transceiver is a physical layer device that prepares data for transmission and then sends to, and receives data from, another transceiver. The transceiver detects connection and provides the low level USB protocol and signaling. The term "transceiver" indicates an implementation of both transmit and receive functions. It transmits and receives, encodes and decodes data, provides error indication, implements buffers to stage data until it can be managed, and adjusts for the clock rate from the serial stream on the USB SuperSpeed bus to match that of the “link layer” higher up on the communication stack.
DPDT Relay for UPS
Simply put, a relay is a switch that is controlled electrically. Relays are often necessary to control high power/current/voltage circuits with a low-power signal while maintaining complete electrical isolation between them.
Many relays are electromechanical in nature; the control signal energizes an electromagnetic coil creating a magnetic field. This field exerts a force on a movable armature of ferromagnetic material (such as iron) which makes or breaks the electrical connection.
Solid State Relays (SSRs) are another common type, and unlike their electromechanical equivalent, they have no moving parts. Instead, one or more transistors, such as a MOSFET, are used to provide a similar function. Electrical isolation must be added in this case, often by using an on-chip optocoupler.
The term “DPDT” stands for “double-pole, double throw” and is equivalent to two changeover switches controlled by the same actuator or input signal.
Displays for UPS
LCD means "liquid crystal display." It is an electronically driven flat panel screen that orients liquid crystals within the panel in a direction that blocks or transmits light coming from behind the panel. LCDs are a low cost, energy efficient visual display that can be controlled in segments or as individual pixels, in shades of black and gray or in full color. LCDs have most commonly replaced bulky cathode ray tubes in televisions and computers and are available in all sizes. Liquid crystals were first discovered in 1888, but were first put into common use in the early 1970s as electronic digital-display watches.
High Speed Optocouplers for UPS
An optocoupler is a device used to provide electrical isolation. Isolation is critical for protecting both an electronics system and the user from potentially hazardous voltages. An optocoupler consists of at least two functional parts: an LED to translate the electrical input signal into light waves, and a photodetector, such as a phototransistor or photodiode, to convert the optical signal back to an electrical output. There is no conductive path through the device, so the output is considered opto-isolated from the input.
USB Receptacles for UPS
USB plugs and receptacles are designed to reduce human error by their unique shape; they fit together in only one way. USB plugs and receptacles are Type A (connecting to hosts or hubs) or Type B (connecting to devices) and are available 3 sizes: standard, mini, and micro. Type A plugs always face upstream, Type B faces downstream. USB is used in many applications covering all areas of electronics that require communication, but more commonly with devices that need fast or easy connections for interaction with computers. Since USB provides a small charging current as well, it is becoming a de facto standard for charging portable devices.
DC/DC Converters for UPS
DC/DC regulators are circuits that convert DC voltage from one level to another and maintain that voltage at a constant level. Electronic systems often have several sub-circuits, each with its own voltage level requirement that may be higher or lower than the main power supply. Step-up (boost) converters raise a voltage to a higher level, while step-down (buck) converters lower it. Some DC/DC converter types can raise or lower voltage, such as "buck-boost" converters. DC/DC converters may offer options such as multiple softstart levels, undervoltage lockout, protection against overvoltage and undervoltage, and programmable short-circuit protection. All of these devices are considered to be in the same category of integrated chips, typically categorized as power management devices.