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1、1Linear Technology Chronicle August 1996Products of the MonthA Showcase of Linear Technologys Focus ProductsLinear Technology ChronicleAugust 1996Vol. 5 No. 8, LTC and LT are registered trademarks of Linear Technology Corporation.Micropower Single Cell Boost Switcher in 8-Pin MSOP Shrinks Power Conv
2、ersion CircuitsLow Power 8th Order Lowpass Filter in SO-8 Package. 2 Micropower Voltage-to-Frequency Converter . 3 Power Factor and PWM Controllers for 150W to 3000W Applications . 4Inside This Issue:The LT1307 combines small packag- ing and high frequency operation to provide the worlds smallest si
3、ngle cell boost DC/DC converter. Up to 75mA of output current at 3.3V can be generated from a depleted (1V) cell. Efficiencies as high as 80% are obtained with 1.5V to 3.3V con- version at 50mA. The LT1307 is offered in a new 8-lead MSOP package, less than two- thirds the size of an 8-lead SO packag
4、e. This extremely small solution makes this switcher appropriate for many new minia- ture applications.Fixed 600kHz frequency operation allows the use of very small and inexpensiveceramic output capacitors with values of 10F usable for most applications. These surface mount capacitors can save 20 to
5、 30 in solution cost over tantalum capaci- tors, formerly required for this function. Inductor size and cost is also reduced by using standard 10H surface mountable devices. These small components and the 600kHz fixed switching frequency make the LT1307 ideal for compact communications systems, such
6、 as pagers and modems, where it is essential to keep switching noise out of the intermediate frequency (IF) bands.The LT1307 also uses Burst ModeTM operation at low load currents to maintainhigh efficiency. Even in Burst Mode opera- tion, there is no interference with 455kHz IF frequencies. The low
7、switch saturation voltage (VSAT) of the LT1307 minimizes switch losses and provides the high effi- ciency. An onboard comparator is included for low-battery detection.The LT1307 is available in an 8-lead SO, 8-lead PDIP as well as the new 8-lead MSOP package. It is well suited for pager applications
8、, which generally require opera- tion specified at 20C. The 0C to 70C temperature range devices are guaranteed to function at 20C, while the industrial temperature specifications are guaranteed for 40C to 85C operation. For a data sheet and evaluation samples of the LT1307, contact your local Linear
9、 Technology sales office.VINSW FB LT1307L1? 10HD1LBOLBISHDNSHUTDOWN100kR2? 604k? 1%3.3V? 75mAR1? 1.02M? 1%680pFFOR 5V OUTPUT: R1 = 1M, R2 = 329kC1:?MURATA-ERIE GRM235Y5V105Z01? ?MARCON THCS50E1E105Z? ?TOKIN 1E105ZY5U-C103-F? C2:?MURATA-ERIE GRM235Y5V106Z01? ?MARCON THCS50E1E105Z? ?TOKIN 1E106ZY5U-C3
10、04-F? ?1307 F01C1? 1FC2? 10F1.5V? CELLVCGNDD1:?MOTOROLA MBR0520L? L1:?COILCRAFT D01608C-103? ?SUMIDA CD43-100Figure 1. LT1307 Can Be Used as a Single 1.5V Cell to 3.3V Boost ConverterIndustrys Smallest Dual 12-Bit DAC Fits in SO-8 PackageThe LTC1446 is a dual 12-bit voltage output digital-to-analog
11、converter that is complete with two rail-to-rail voltage out- put amplifiers, an internal reference and a 3-wire cascadable serial interface, all packed into an 8-pin SO or PDIP package. The 4.095V output voltage is guaranteed even when driving heavy loads with a re- duced supply of 4.5V. The DAC ou
12、tputs drive capacitive loads of up to 1000pF, over twice that of competitive solutions. It con- sumes just 5mW typical (7.5mW max) from a single 5V supply, making it the best solu- tion for portable and battery-powered equipment, general trim pot applications and industrial control applications.The
13、excellent typical differential non- linearity (DNL) of 0.2LSB not only guarantees 12-bit monotonic performanceContinued on page 2Burst Mode is a trademark of Linear Technology Corporation.Figure 2. New MSOP Package Is Smaller Than SO-8ACTUAL? SIZES08MS8LTC2Linear Technology Chronicle August 1996LTC1
14、446 from page 1is compatible with SPI, QSPI and MICROWIRETM protocols. Power-on reset ensures that the outputs are at zero-scale af- ter a power-up sequence, easing initial software overhead.The LTC1446 is screened to the com- mercial and industrial temperature ranges. Contact your local Linear Tech
15、nology sales office for a data sheet and evaluation samples.but also provides exceptional performance in closed loop control systems. The LTC1446 3-wire serial interface allows several DACs to be daisy-chained to save board space andMICROWIRE is a trademark of National Semiconductor Corp.Low Power 8
16、th Order Lowpass Filter in SO-8 PackageThe LTC1069-1 is the industrys first monolithic, 8th order, elliptic lowpass filter that fits in an SO-8 package. It requires no external components except for power sup- ply bypass capacitors. With a single 3.3V supply, it draws just 2.0mA (typ) and has a dynamic
