Design Ideas conquer power supply applications

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Charles H. Small
A software solution is the simplest way to compensate the system offsetwhen interfacing a resistive bridge sensor with an Analog to digitalconverter (ADC) powered by a +5V single-supply power source. "Circuitcompensates system offset of a load-cell-based balance" shows how toachieve hardware compensation using a microcontroller which on power-upstarts a software routine to reset the system offset.
"Voltage doubler uses inherent features of push-pull dc/dc converter"presents a minimum part count, wide range, voltage doubler using theinherent voltage-doubling characteristics of a one-transformerpush-pull DC-DC converter. The circuit exhibits a wide input voltagerange from 5V to 30V and provides a typical power output of 1W to 4W atmoderate efficiency.  
A simple circuit in "Voltage timer monitors line-connected ac loads"uses a 1-wire counter and opto-isolator to monitor the elapsed timeover which a line-connected ac load is energized. You can then accessthe elapsed-time count over the standard 1-wire protocol.=>半导体,微电子,集成电路,IC,工艺,设计,器件,封装,测试,MEMS5 i. A. |" I: y
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Powering 20 to 30 white LEDs from three alkaline cells presents aninteresting problem for the conventional boost converter. The requiredboost ratio and duty factor are simply not practical. If you aredetermined to design with off-the-shelf components, "Cascaded converterboosts LED-drive capability" shows how to cascade two stages of boost.
In multiple-output power supplies you need to sense the current drawnby each output and deactivate the power supply in the event of anoverload. You could use the Vbe threshold voltage of ~0.6V of a bipolartransistor to trigger the power-supply protection circuits. Whileeconomical, the transistor's threshold varies excessively overtemperature and hence the protection level is not stable. The circuitin "Dual transistor improves current-sense circuit" eliminates the Vbetemperature variation problem.

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