Traditionally, precision full wave rectifiers1 used in a range of instrumentation applications have employed between 7 and 9 discrete circuit components. These are typically 2 op-amps, 2 diodes and 3 to 5 resistors. This article will show that an alternative approach, using a standard current monitor IC, reduces the component count to just five and greatly simplifies circuit configuration and produces a more elegant overall solution.
Computationally intensive DSP functions often require hardware acceleration. Increasingly, designers are implementing their DSP algorithms in FPGAs because they offer better performance than DSP processors. Benchmarks show that FPGAs execute turbocoding, GPS correlation, H264 and other DSP functions much more quickly than DSPs.
While LEDs offer mainstream lighting applications benefits such as long life, durability and high efficiency, the lifetime of an LED product may be significantly shortened without proper thermal management safeguards in your design.
Traditionally, IGBTs have addressed applications requiring high-voltage and -current ratings and relatively slow switching frequencies. When the switching frequency is low, the inherently low conduction losses resulting from the device’s low VCE(on) (collector-to-emitter saturation voltage), which derive from the IGBT’s minority carrier operation, outweigh the
Managing power is a critical requirement for all electronic equipment from notebooks to PDAs to storage peripherals. Power management ICs can optimize power usage to match the constantly changing demands of whatever task the device is carrying out. There are several important criteria to consider when selecting the best IC for an application.
The field of video surveillance has seen explosive growth in the last 3 years. The convergence of heightened security demand and innovative technology, in the acquisition, transport, analysis and storage of quality video has resulted in a massive deployment of cameras and systems in a number of venues. Major cities, transportation centers, highways, military installations, retail and business centers are all covered by the un-blinking gaze of millions of cameras. According to some reports, the UK alone has over 15 million security cameras.
In today’s world, wireless networks are becoming more ubiquitous, and they are implemented using a variety of protocols that are specifically designed for radio frequency systems. Some protocols that are in use are proprietary to individual vendors, while others are industry standards. Recently, a lot of attention has been given to 802.15.4 and ZigBee, but there is still some ambiguity as to what is different about 802.15.4 and ZigBee and what kind of networks or systems would benefit from these particular protocols.
New power regulations are redefining the meaning of efficiency in power supply design. Driven by increasing demand for electrical power worldwide, government agencies and industry groups are adopting new environmental standards that are designed to reduce power consumption by improving power efficiency. In the U.S. for example, the Department of Energy (DoE) and Environmental Protection Agency’s (EPA) Energy Star program grants certification to electronics devices that meet a range of standards for power consumption. More recently, the State of California through the California Energy Commission (CEC) has implemented a mandatory program to implement more stringent power efficiency standards for external power supplies and consumer audio and video equipment sold in California.
Power factor is the ratio of the actual power used to the apparent (reactive) power that a piece of equipment draws from the alternating current (AC) line. The reactance of large capacitors or inductors can cause the apparent power drawn from the line to exceed the actual power used, resulting in low power factor (PF). The lower the PF, the more energy is lost along the AC power line. The result is higher electricity bills for the utility customer. That lost energy also lowers the capacity of the utility distribution system.
Electrostatic discharge (ESD) occurs when objects -- including people, furniture, machines, integrated circuits or electrical cables -- become charged and discharged. Electrostatic charging brings objects to surprisingly high potentials of many thousands of volts in ordinary home or office environments. ESD produces currents which can have rise times less than a nanosecond, peak currents of dozens of Amps and durations that can last from tens to hundreds of nanoseconds. Unless ESD robustness is included during design, these current levels can damage electrical components and upset or damage electrical systems from cell phones to computers.
Designers are always on the lookout for semiconductors and algorithms that help to boost the efficiency of appliances with a minimum addition to the overall system cost. Motor-control systems need to compensate for system input changes and can use control algorithms to ensure the efficient operation of the motor. Using advanced algorithms, such as a field oriented control (FOC), motor torque can be controlled dynamically, keeping it constant within the rated speed range (see Figure 1). Toward this, the most commonly used motor-control loop is the Proportional Integral Derivative (PID) controller, which comprises error calculation (reference minus measured variable), compensator (controller), and output generation to the system.
When compared to one time programmable (OTP) or read only memory (ROM) microcontrollers (MCUs), a flash memory-based MCU is distinguished by its ability to be reprogrammed. Many applications today need memory not only for storing the application program but also for storing data, which may need to be updated from time to time and must be retained in the application system, even after power off. For example, with a remote control, the user does not want to lose the preferred settings every time the battery is changed. External serial EEPROM can serve this purpose well, but adding another component to the system means higher system cost, a larger board footprint and degraded system reliability. An MCU with reprogrammable flash memory is a good choice for such an application, particularly if the application program needs a periodic upgrade to a newer version with enhanced features.
Many different standards for wireless communications equipment are in use today. Narrowband communication standards use stronger transmission in a small slice of bandwidth. Wideband standards use lower transmission power across a larger bandwidth. Each standard defines minimum performance characteristics for receivers, and includes specifications such as bandwidth, maximum signal level, and sensitivity. GSM is one narrowband example; the channel bandwidth is 200 kHz. A GSM receiver must have a minimum sensitivity of –104 dBm and be able to tolerate a –13 dBm signal at the antenna. In contrast, CDMA2000 is a wideband standard that uses a 1.25 MHz bandwidth. CDMA2000 receivers need to have a minimum sensitivity of –117 dBm/1.25 MHz and tolerate a maximum signal of –30 dBm at 900 kHz offset.1
One of the most critical factors in designing handheld, portable electronics today is reducing overall system power consumption. With increased consumer expectations, portable devices require longer battery life and higher performance. Even power reductions on the order of 10 mW are crucial to portable system designers and manufacturers.
Small high voltage loads are found in abundance. Be they actuators, motors, solenoids or transformers, power supply or power conversion circuits, all are subject to the relentless quest for better energy efficiency, improved reliability and reduced cost and footprint. For the power switching element within such loads, these technical demands appear to manifest themselves as simply “increased switched power density!” In practice, how can this be best achieved?
New low power 8-bit, 16-bit and 32-bit microcontrollers designed for portable and battery powered handheld products include an impressive set of new features, including low power capabilities. To optimize performance and take full advantage of these MCUs, designers must understand the flexible clocking systems, resource event-driven features, and — perhaps most important — the way to transition to and from standby and other low power modes.
A key problem facing software-defined radio (SDR) designers occurs if the system must support linear-modulation schemes, i.e., modulations which have significant amplitude content. Such modulations present a challenge: either the power amplifier (PA) must be inherently very linear — which generally involves a very high power consumption — or some form of linearization scheme needs to be used.
LEDs are increasingly being specified as replacements for traditional incandescent light bulbs in a variety of general illumination, display and indication applications. As solid state devices, LEDs exhibit much higher reliability, longer life and significant energy efficiency. Integrated control of LEDs is crucial to the design of new solid state arrays for illumination and specialized lighting applications employing multiple LEDs.
Lower output voltages, higher current densities, increasing switching frequencies and smaller real estate are well-known trends in applications such as desktop PCs, servers, telecom point of load (POL) as well as other, similar DC/DC converter systems. Simultaneously, designers have strived to increase system efficiency, reduce total solution cost and simplify their designs. To this end, several design approaches implementing discrete components have been tried and tested. This article follows the evolution of this approach and describes the latest adoption of multi-chip modules for solving these design challenges.
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