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A Transceiver with Delay Cell and Over-current Protection and A Digital Over-temperature Protector for FlexRay ECUsLin, Sheng-Chih 11 July 2012 (has links)
This thesis is composed of two critical circuit designs for FlexRay ECU (Electron-ics Control Unit), i.e., a transceiver with over-current protection, and a digital over-temperature protection circuit.
Regarding the transceiver with over-current protection, to reduce the glitch prob-lem, we propose to use delay cells in the transmitter. In order to avoid the transmitter current which is higher than the upperbound defined by FlexRay specifications, we propose a current comparator circuit to detect the state where the transmitter should stop sending signals.
The temperature protection is required for FlexRay specifications. We propose an over-temperature circuit in the thesis. By utilizing an oscillator-based structure, fre-quency to digital converter (FDC) circuit is developed as the core of the temperature protection mechanism. It will convert the frequency signal and output the sensed tem-perature in a digital code format. The output frequency at different process and temper-ature corners show a linear feature such that the range and accuracy of temperature de-tection is enhanced.
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[en] METHODOLOGY FOR METROLOGICAL EVALUATION OF THE CHARACTERISTICS OF A PTC POLYMERIC RESETTABLE THERMISTOR / [pt] METODOLOGIA PARA AVALIAÇÃO METROLÓGICA DE CARACTERÍSTICAS DE UM TERMISTOR PTC POLIMÉRICO REGENERATIVOREINALDO NIVALDO DA SILVA 22 September 2005 (has links)
[pt] Esta dissertação propõe uma metodologia para avaliação
metrológica de
características do termistor PTC polimérico regenerativo
LP60-110 usado como
protetor contra sobrecorrente e sobre temperatura.
Expressa a determinação
da incerteza de medição dos parâmetros temperatura,
tensão, corrente elétrica
e resistência ôhmica de amostras do dispositivo. O
termistor PTC (Positive
Temperature Coefficient) polimérico regenerativo surgiu na
década de noventa,
como um elemento de proteção muito importante em função de
suas
características especiais. Pode ser usado como protetor de
sobrecorrente e
sobre temperatura, partida de motores, compensação de
temperatura e em
circuitos em geral. Para realização da pesquisa foi
montado um circuito
constituído de um cronômetro, dois multímetros, uma fonte
de alimentação
estável, uma carga resistiva variável colocada em série
com o dispositivo
termistor PTC polimérico regenerativo LP60-110 e este foi
colocado em uma
estufa térmica a seco com um termopar tipo K, o que
permitiu controlar sua
temperatura. Este circuito possibilitou estabelecer de
forma simples uma
corrente de limiar do termistor PTC circulando pela malha,
tornando este
sensível apenas à variação da temperatura. Os dados
registrados foram
suficientes para construção de curvas características e
análise para
determinação da Incerteza de medição. Devido ao fato de
não existirem muitas
informações sobre o sensor no mercado, a contribuição
principal deste trabalho
é a sistematização do levantamento das características do
termistor para a
verificação da confiabilidade dos dados do fabricante,
juntamente com sua
incerteza, fornecendo ao mesmo tempo informações ainda não
disponíveis ao
projetista de sistemas de proteção. / [en] This research aims at the development of a methodology for
experimentally characterizing a PTC polymeric resettable
thermistor LP60-110,
used as an overcurrent and over temperature protection
device. Uncertainty of
measurement of the parameters, such as temperature,
voltage, current and
ohmic resistance is also determined. The PTC (Positive
Temperature
Coefficient) polymeric resettable thermistor started to be
used in the 90`s, as a
very important protection device because of its special
characteristics. It can be
used as an over current and over temperature protection
device in electronic
circuits, for engine start-up and as a temperature
compensation device. An
electric circuit was built to measure the thermistor
characteristics, consisting of
an stable voltage source and a variable resistance in
series with the thermistor,
which was place in a dry oven. A K type thermocouple was
attached to it, so
that its temperature could be measured and controlled. A
chronometer and two
multimeters were used as measuring instruments. By
gradually decreasing the
circulating current through the circuit, the Joule effect
could be neglected, and
the thermistor resitance was made only a function of
ambient temperature,
which is easier to measured. The acquired data were used
to build several
characteristics curves, which were analyzed and compared
to the available
ones from the manufacturers. Due to the fact that there
are not many available
information about the sensor in the market, the main
contribution of this work is
the development of a systematic procedure to obtain the
thermistor
performance data, so that the manufacturer data can be
verified, together with
its uncertainty, providing at the same time information
not presently available in
the market for system designers.
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Equilibrium Fractionation of Sulfur Isotopes Between Pyrite, Sphalerite and Galena as a function of Temperature. / Equilibrium Fractionation of Sulfur IsotopesGrootenboer, John 11 1900 (has links)
<p> The existence of significant and consistent fractionation of sulfur isotopes in natural coexisting sulfide mineral pairs is demonstrated. Such fractionations are shown to depend exclusively on the mineralogy of the assemblage and temperature of equilibration, consistent with a process of fractionation during equilibrium exchange of sulfur isotopes between the sulfide phases . The fractionation of sulfur isotopes between galena, sphalerite and pyrite has been determined experimentally over the temperature range 300-725°C . The fractionation for each mineral pair is shown to vary as T^(-2) so that three isotope geothermometer s have been calibrated. Experi mental results are applied to natural sulfide assemblages to determine the temperature of equilibration and extent to which isotopic equilibriurn has b een attained. </p> / Thesis / Doctor of Philosophy (PhD)
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