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292 results found, displaying items 141 - 160
LED Charge Pumps Get Smarter
Five tri-mode, high-efficiency charge pumps for white LED backlight and color LED applications combine a load switch (13) and a high-efficiency (1.53 or 23) charge pump with an internal sensing circuit that monitors the required voltage on each constant current-sink input. The load switch and charge pump modes are set based on the input battery voltage and current sink input voltage. Advanced Analogic Technologies' AAT3151/2/3/6 products can drive four or six individual LEDs with a...
Miniature SIP Converter Family Offers A Wide Voltage Selection
For board-level applications with very tight space requirements, a family of converters in miniature SIPs features tight line load regulation, continuous short-circuit protection, and 3 W of output power in a miniature SIP package. The 15 models in MicroPower Direct's D300RP series operate from 5-V dc, 12-V dc, or 24-V dc inputs and provide single outputs of 5, 9, 12, 15, or 24 V dc. Standard features include ±0.5% line/load regulation, 1000-V dc input/output isolation, continuous...
Tiny Boost Converters Drive Three, Four, Or Five LEDs
A family of synchronous boost converters in 1.5- by 1.5-mm packages can power up to five series of white LED backlights in smart phones, PDAs, digital still cameras, and other handheld electronics. Texas Instruments' TPS6106x family of specialized dc-dc converters supports input voltages from 2.7 to 6 V and integrates a 400-mA power MOSFET and synchronous rectifier, eliminating the need for an external series Schottky diode. Their 1-MHz fixed switching frequency enables the converters to...
Forecast Kudos, APEC
Our January 13 Technology Forecast was a monumental effort. Along with the great stuff in print, look for commentaries by our staff and industry pros online at www.elecdesign.com. I'd also like to thank the folks who spent hours briefing me: Linear Technology's Robert Dobkin; Analogic Tech's Richard Williams; ADI's Lew Counts, Steve Sockolov, and Eric Nolan; Intersil's Simon Dutton; Artesyn's Todd Hendrix; True Circuit's John Maneatis; IR's Steve Clemente; ON Semi's Jeff...
High-Power LED Driver Accepts Wide Input-Voltage Range
The advent of high-power LEDs that can replace incandescent bulbs has produced a need for circuits that efficiently match the LEDs to available power sources (batteries, car electrical systems, etc.). The circuits should also be able to regulate and control the LED light output, despite variations in output voltage from the power source. The circuit of --->Figure 1---> starts and operates a 1-A LED from a voltage that...
Multiphase Voltage Regulator Tackles 150-A Applications
Power demands of the latest microprocessors from AMD, IBM, Intel, and other vendors continue to soar. Indeed, CPUs currently under development for next-generation servers require 150 A or more, while desktop processors require 120 A. Along with these stringent requirements come additional constraints such as cost, board area (power density), and thermal environment, which further inflame the design challenge. To explore the various options for voltage-regulator design, this...
Stored Energy In Relay Coil Boosts Op-Amp Supply Voltage
The circuit shown in the figure uses stored energy in the multiplexer relay coil to boost the power-supply voltage from 3.3 to 5.1 V. This extra voltage enhances the amplifier's ability to produce a larger output voltage suitable for interfacing...
The Joy Of Tradeshows
Oh, the things you can learn trolling the aisles at tradeshows and talking to engineers! There was lots to check out last month at Power Systems World in Detroit. Tabtronics CTO Victor Quinn presented a seminar about evaluating...
Double Your Output Current With Parallel Voltage Regulators
To improve efficiency in high-power applications, voltage regulators can be used in parallel to double output current capability—if a means of forcing current sharing is provided. One circuit approach uses sense resistors in...
Double Your Output Current With Parallel Voltage Regulators (Part 2)
Example 4: This paralleling technique using the sensing circuit as shown in Figure 5 has been demonstrated with a dual-phase, voltage-mode controller (LM2647) to combine 30-A, 1.2-V channels into a single 60-A output without introducing added loss....
Efficient Step-Up Converter Steals Power From Parallel Port
The circuit shown in Figure 1 steals energy from a PC's parallel port or from any limited-energy source. To use the available energy, such power-conversion applications usually require very high...
Flexible Power Amplifier Doubles As Process Controller
Using integrated drivers and controllers with flexible architectures to satisfy multiple applications can reduce design time. The LMD18201 motor driver is billed as a 3-A full-bridge type. But scrutiny of the data sheet reveals that it can also...
EEMBC Adds A Metric
A whole segment of the power industry is dedicated to supplying the fluctuating needs of microprocessors and ASICs at the point of load. Yet to date, there has been no consistent way of defining how those loads vary under real-life conditions....
"Zero-Drop," 0.5-A Voltage Regulator Costs Under $1
Low-drop voltage regulators get wide application soon after they appear on the semiconductor market, mainly because of power savings in ac-dc supplies. Proceeding in the same direction to minimize the losses, we developed a "zero-drop" linear...
Op Amp Idles To Save Power In Smoke Detectors, Other Sensors
With its power-saving mode, the LMV422 operational amplifier lets designers reduce power consumption while maintaining an active circuit. Thus, there's faster turn-on times in smoke detectors and other sensor interface applications where...
Power Supplies Kick Out Rated Power Times Two For 10-Second Bursts
Where 24-V peak-current demand is needed for a short duration, the 5- and 24-V ZWD family of dual-output power supplies can deliver 200% of the nominal current rating for up to 10 seconds. These supplies are available with a 5-V, 5-A output for...
Fan-Free 1U Supply Reaches 400 W
The Series 1720 1U-high rackmount dc-dc converters provide 400 W without the need for fans. Input voltages include 24, 48, and 130 V dc. Standard isolated and regulated output voltages are 12, 24, and 48 V dc. Other combinations are available. The...
Voltage-Controlled Current Source Uses Two Op Amps
One challenge in circuit design is building a good current source, especially when the load is variable or the current must be controlled with a voltage source. The figure shows a simple, low-cost voltage-controlled current source using two op amps...
Efficiently Reduce High Supply Voltages To Accurate Low Voltage
When a relatively high input of 24 V or more must be very accurately regulated down to a much lower voltage, such as 3.3 V or less, with very low quiescent current, there's no off-the-shelf solution available. For example, if one needs to...
White LED Voltage Booster Uses 555 Timer IC
This voltage-booster circuit for driving one or more white LEDs uses a 555 timer as its main element (see the figure). The timer, IC1, functions as a resettable astable multivibrator where R1, R2, and C2 are...
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