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292 results found, displaying items 241 - 260
Self-Powered Dummy Load Checks Out Multiple-Output Power Supplies
This spartanly simple, adjustable, active current load for the 20-mA to 20-A range is powered by the very current it controls. A benchtop box with two to four of these loads makes an excellent instrument for checking out multiple-output power...
3.3-V Supply Taps Power From The 12-V PCI Bus
The backplanes of popular multi-supply buses (such as VME, VXI, and PCI) each provide power-limited outputs of 3.3 V, 5 V, and ±12 V (or ±24 V). If adding line cards to these systems increases the requirements for 3.3- or 5-V power, the...
Micro-UPS Features Rapid Battery Recharge
Every circuit needs some sort of power source. Frequently, the success of a circuit will be made or broken by the convenience and flexibility of its power supply. This is particularly true of portable instrumentation, which often must combine...
Off Line-UPS Offers Backup Power-Source Alternative
With increased dependency on electric power for various domestic, commercial purposes and the seemingly declining capacity of power utilities in many countries, the need for additional backup power sources is on the rise. Various modules are already...
Universal Off-Line Power Supply Uses Few Components
Certain off-line universal powersupply applications will have the ac input voltage vary from a minimum of 90 V ac to a maximum of 240 V ac, and the dc current requirements will drop to less than...
Primary-Control Sensor Regulates High-Voltage Power Supplies
One popular approach to producing a variable EHT supply with an output range of a few kilovolts is via control of the input voltage to the EHT transformer’s primary using SCRs or triacs. During...
Li-Ion Battery Protection Circuit Draws Only 4.5 μA
Figure 1 shows an ultra-low-power, precision undervoltage-lockout circuit. The circuit monitors the voltage of a Li-Ion battery, disconnecting the load...
PIC Microcontroller Self-Regulates Its Power Supply Using PWM
Developing consumer products can often involve the design of small, low-cost, handheld, battery-powered circuits with an embedded controller. Thanks to the availability of inexpensive 8-bit...
Micropower Backup Supply Operates From Phone Line
Designers of electronic circuits for telephone systems are constantly enticed by the possibility of utilizing the “free” power provided by the telephone company. The catch involved in pulling off...
Constant-Voltage/Constant-Current Battery Charger Is DAC-Controlled
Many portable products require some form of battery-management system. In large systems, the battery-management system may have to deal with different battery chemistries and cell...
Charge Pump Aids High-Power Switch-Mode Regulator
Switch-mode buck-regulator ICs can deliver high power with high efficiency, but they seldom operate with input voltages below 3 V. That restriction excludes the use of single-lithium-ion-cell...
Efficient Charge Pump Converts 5 V To 3.3 V
The common approach for generating 5-V and 3.3-V supply rails in portable applications is to convert the main 5-V supply to 3.3 V using a lowdropout (LDO) linear regulator. LDOs offer low cost,...
GaAsFET Power Supply Has Negative Gate Bias, Automatic Power-Up Sequencing
GaAsFETs are frequently used as high-power RF amplifiers for cell-phone repeaters and similar devices. In general, they require a negative supply voltage of −4 V to −5 V to bias the...
Simple Charger Targets Lithium-Ion Batteries
Lithium-ion batteries are popular in portable equipment due to their high energy densities. Many handheld products are designed to operate from a single lithium-ion cell with an operating voltage...
Keep Standby Power Below 50 mW On Universal Mains
The quest for low standby power represents one of the most challenging tasks for switch-mode power-supply (SMPS) designers. This can become a daunting task when tackling very-low-output loads—the...
Current-Source Power Supply Is Digitally Programmable
The circuit shown provides a continuous, regulated, and adjustable dc current as required for certain electronic functions, such as the LED backlighting of LCD display panels (...
Extend The Input Range Of Instrumentation Amplifiers
The XTR105, XTR112, and XTR114 from Burr-Brown are a family of two-wire, 4-20 mA current-loop transmitters with instrumentation-amplifier input stages. The front end is designed to be used with a...
A Low-Cost High-Performance DC-DC Converter Topology
Flyback and forward converter topologies are commonly used in switchmode power-supply design. However, each topology has certain limitations that are hard to resolve. In flyback...
Forward Converters Drive Power MOSFETs At Up To 500 kHz
Simply by combining two simple circuits, high-gate-capacitance MOSFET transistors can be driven at up to 500 kHz with galvanic isolation (Fig. 1). The...
Hot Swap Higher Voltage Supplies
Some applications, such as communications, fault-tolerant computer systems, and networking, require circuit boards to be inserted into a backplane without turning the power off. The bulk supply...
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