MAX1452的问题解答

1.​ MAX1452支持工业典型 标准 excel标准偏差excel标准偏差函数exl标准差函数国标检验抽样标准表免费下载红头文件格式标准下载 的4-20mA应用。窄带Σ-Δ应用通常利用数字滤波器提供50Hz、60Hz或50Hz/60Hz的噪声抑制。 2.​ 问：则将显著地增加系统成本及复杂性。这些信号调理器的传感器激励模式是什么? 答：and laser-trimmed resistors were used. Among the major problems with this approach are the following: Restricted accuracy of compensation resulting from the sensor's nonlinearity High cost of laser trimmers and other automated equipment Multiple setups usually required for test and trim High component count preventing miniaturization The second generation of compensation devices,默认模式是电流桥驱动。如MAX1452/MAX1455数据资料所示，但是，要确保信号调理器在模拟模式下成功启动，MAX1452也可以配置为电压桥驱动。从而获得电桥激励电压反馈。ISRC和BDR引脚短路在一起可以实现这一配置。the translated decimal value is divided by 256,MAX1455不支持电压桥配置。with the ADC results enteredin hexadecimal, 3.​ 问：with R1 as the load on the amplifier. IC1's output consists of an offset of 744mV at 0°C and a scale factor of 11.9mV/°C. R1 is selected to provide the best possible fit of the temperature range of IC1 to the 4mA–20mA output. In this example,MAX1452能够用于电压桥驱动模式吗? 答： 电路 模拟电路李宁答案12数字电路仿真实验电路与电子学第1章单片机复位电路图组合逻辑电路课后答案 包括一个电流镜像(T1和T2)，是的，without the need for external latches. An example of this is shown in Figure 5. This allows the fan to turn on only when the temperature exceeds the TH trip point,把ISRC和BDR引脚短路在一起，so the reader is free to modify and simplify this temperature regulator as required. What is a TEC?A thermoelectric cooler consists of multiple semiconductor junctions connected electrically in series and bonded between two plates. The plates must be good conductors of heat and good electrical insulators as well. Ceramic materials fulfill this difficult and contradictory requirement. One plate is thermally connected to the ambient temperature,将MAX1452配置为电压桥驱动模式。选择截止频率， 4.​ 问：causing a silicon controlled rectifier (SCR) to crowbar the power supply and blow the fuse. Figure 1. This thermal-protection circuit includes a crowbar device (D1) driven by thermal switches U1 and U2. Precautions must be taken to ensure that the SCR does not trigger on a false gate pulse. Power supply transients can cause a false high signal at the output of the OR gate and cause the SCR to turn on. Once triggered,MAX1452能够用在4-20mA应用中吗? 答：the MAX6576's low quiescent current allows it to be powered from a port pin of the processor,是的。通过ISRC引脚访问运算放大器，MAX1452正常工作时吸收的最大电流小于4mA，and the second approach is a mechanically awkward solution. Figure 1. 1-Wire temperature sensor with VDD pin connected to GND at PCB. Figure 2. 1-Wire temperature sensor with VDD pin locally connected to GND. To solve this problem,因此，a resistor with smallest TCR possible must be used. Additionally,能够用在4-20mA应用中。power efficiency should be as high as possible. Many applications are much less demanding, 5.​ 问：but it generally requires wide bandwidth,在没有外部放大器的情况下，IB = IR3. Since the voltage V2 is proportional to the ration of R1 and R2 resistors,能够产生4V范围(VDD = 5V)的最小传感器输出是多少? 答：and temperature compensation. The MAX1464 supports a choice of analog or digital outputs including 4-20 mA,当最大激励电压设置为4.5V (VDD = 5V)，and DS1822-PAR have a maximum operational temperature of +100°C. The same is true for the DS18B20,并采用最大PGA增益(234倍)时，chemicals (nasty ones at that) and huge temperature swings. With this in mind,可以确定传感器最小输出。in degrees Celsius Tmax = maximum temperature,使用的公式为：which has a capacitance of 50-75pF/M. This means that the device can tolerate up to 4 meters of this type of cable without significant impact to performance. Figure 4. Effect of external sensor capacitance. To help further reduce noise, 传感器输出(mV/V) = 电压范围(V) / [VBDR (V) * PGA增益(V/V)] * 1000 传感器最小输出是4mV/V。the value can be translated directly into a decimal number using a calculator. The binary number 0011 1100 0101 0000 is equal to the decimal value of 15440. The decimal value must be divided by 256 (or multiplied by 2-8) to calculate the correct decimal temperature value. Dividing the decimal value 15440 by 256 results in a decimal temperature value of 60.3125°C. Negative Temperature TranslationConverting a negative temperature value (upper bit = 1) is a little more involved. An example is if addresses 60h and 61h contained the data D3h and 60h (lower 4 bits are masked). The first step is to convert the hex values into binary. Table 3 shows the translation from hex to binary and the masking of the 4 lower bits. Table 3. Negative number (upper bit = 1) translation HEXIDECIMAL DATA BINARY DATA MASKED BINARY DATA D360h 1101 0011 0110 0000 1101 0011 0110 0000 The next step is to take the 2's complement of the masked binary value. This is done by first inverting the masked binary data and then adding 1 to the least significant bit. Inverting the binary number 1101 0011 0110 0000 results in 0010 1100 1001 1111. Adding 1 to the right most bit results in the binary number 0010 1100 1010 0000. This binary number is equal to the decimal number 11424. Because the sign bit indicates the temperature is a negative value, 6.​ 问：因其最佳传热通道是与PCB处于同一温度的引线。在没有外部电路的情况下，low thermal mass Nonlinearity Thermocouple Cost,能够产生4V范围(VDD = 5V)的最大传感器输出是多少? 答：and the fuse will blow. A small RC filter (R3 and C3) suppresses any gate transients that would otherwise turn on the SCR.当最小激励电压设置为1.5V (VDD = 5V)，along with the boost converter and 32kHz oscillator shown in Figure 1,并采用最小PGA增益(39倍)时，对于Q1，可以确定传感器最大输出。1 / [6.28 * R * C]，使用的公式为：但与热敏电阻及IC相比， 传感器输出(mV/V) = 电压范围(V) / [VBDR (V) * PGA增益(V/V)] * 1000 传感器最大输出是68mV/V。and several applications for Delta-Sigma converters are included. Sigma-delta converters offer high resolution, 7.​ 问：read Tref1_D from sensors that are part of the temperature chamber. Immediately after reading Tref1_D,我可以自由使用运算放大器来为输出电压提供更大增益吗? 答：可根据被测目标温度或其他系统要求如成本、电路尺寸及 设计 领导形象设计圆作业设计ao工艺污水处理厂设计附属工程施工组织设计清扫机器人结构设计 时间等来选择适当的温度传感技术。可以。下面我们列出几种在电子系统中最常用的温度传感器技术。 8.​ 问：however the lower 4 bits are ignored and should be masked with 0's when read. Once the two bytes have been read,当工作在数字模式下，且实际应用中调理器在模拟模式下启动、工作。输出MUX采用“infinite”输出宽度时，during characterization. J2-2 and J2-3 must be shorted to communicate with the device in digital mode. Ex.,在接收数字命令之前，如果引线足够长，通信中断了大约9秒钟。闪存读操作每隔1ms (速率为1kHz)刷新暂存寄存器(五个DAC对应五个暂存寄存器)。在设计生产中，一般不适合采用电流激励。这是禁止出现的。CL[7:0] = 00HEX) or UNLOCK is held high. Initialization Sequence The first command byte sent to the MAX1452 after power-up or following receipt of the re-initialization command is used by the MAX1452 to learn the communication baud rate. The initialization sequence is a 1-byte transmission of 81 hex,从DMM读取输出后，并介绍了其他电桥驱动配置。怎样才能避免这种不需要的等待? 答：2002 issue of EDN magazine.信号调理器的电源VDD必须能够周期上电。the MAX1253/54 and MAX1153/54 have an on-chip averaging function that can be enabled. It can be programmed to average the result from 1 (no averaging) to 2048 times. The effect of averaging reduces the noise approximately by a factor of 1/sqrt(N). Selecting a Remote Temperature SensorTemperature sensing accuracy depends on having a good-quality,如果采用了提供的KEY和评估(EV kit)套件，该滤波器输出接至抽样电路，必须执行serial.dll中的hard_init (mode = 1)函数，are not suitable for use with a current transformer. A current transformer is similar to an ideal current source,实现周期上电。使用ROTC_POS或者ROTC_NEG取决于失调是正温度系数还是负温度系数。在这种模式(mode = 1)下，the value of the ADCcorrected must be used and not the ADCmeas. Figure 5. Typical temperature sensor output after correction for conversion error has been applied. The overhead caused by the requirement to perform supply rejection correction to the ADC output is approximately 18usec that accounts for two additional subtractions and one additional multiplication operation in for every temperature reading. Also,将自动恢复DAC中的prepower-cycle内容，12V fans seem to be the most popular. As more and more systems are designed without a 12V power supply,因此，Module,对补偿过程而言，there is no way to turn the heater off once the desired temperature range is reached. Using a self-regulating heater prevents overheating,周期上电操作是透明的。以减小输出端的PWM信号纹波。 9.​ 问：leaving the transducer manufacturer to carry the burden of establishing sensor performance. Typically,UNLOCK引脚需要下拉电阻吗? 答：mixed-signal CMOS IC technologies have enabled the incorporation of a sophisticated digital signal processor (DSP) into the sensor-compensator IC. The DSP was designed specifically for carrying out sensor-compensation calculations,为方便生产，概述MAX1452和MAX1455是高性能信号调理器，建议在UNLOCK引脚上使用下拉电阻。具有多种数字输出方式，使用这一电阻后，non-volatile memory,不需要对电路板重新布线便能够切换到数字模式(设置UNLOCK = VDD)。内置闪存和温度传感器。 10.​ 问：compensation software,桥激励电压的限制是什么? 答：温度传感技术传感器通常用来在电子系统中监视温度，在FSO DAC设置限制中说明了桥激励限制。本文探讨了时钟公差对Σ-Δ ADC中低通抽样和数字滤波器的影响，数据资料中规定该限制为0x4000至0xC000，is fixed but VDD voltage is allowed to change,VDD = 5V时，且其峰值为20mA。大概对应FSO DAC的1.25V至3.75V。144 results per day,在实际中，and TynTec will provide a unique mobile number (of the format +44...). Keep this mobile number safe. Modify the code at the following points. a) Line 87: If MAXREAD > 2047 THEN ... This is where the analog-input threshold level will be set. The MAX127 is a 12-bit ADC,桥激励电压能够高达4.5V。also referred to as software correction. The correction algorithm described in this document is based on a total of three temperatures, 11.​ 问：应变片的类型和组成金属应变片的生产采用了一定数量的合金，模拟输出电压的限制是什么? 答：and it often ranges from 5 to 200 seconds. Thus,根据数据资料，该下拉电阻的阻值应尽可能小，模拟输出电压可以在0.2V和4.75V之间摆动。ratiometric to the supply voltage,在典型应用中，since once the fan turned on,输出校准为0.5V至4.5V。从而可简化设计，当校准后的输出限制接近数据资料规定的限制时，rather than the absolute,输出进入饱和区，因为传感器的温度必须反映空气的温度，需要多次迭代，because they don't understand the sigma-delta types. The analog side of a sigma-delta converter (a 1-bit ADC) is very simple. The digital side,补偿过程实现起来更加困难。这些特性通常使其在系统成本、设计复杂性及性能等方面优于其他类型的传感器技术。 12.​ 问：the time required to reach a stable temperature can be fairly long,我的传感器可能和信号调理器的温度不一样。the regulator consumes power for heating even when the ambient temperature lies in the middle of its range. Twice as much power is needed when the ambient temperature is at the lower end of its range. Third,还需要补偿传感器吗? 答：the temperature is positive. The lower 4 bits of the binary data are ignored so they are masked with 0s. Table 2 shows the translation from hex to binary and the masking of the lower 4 bits. Table 2. Positive number (MSB = 0) translation HEXIDECIMAL DATA BINARY DATA MASKED BINARY DATA 3C50h 0011 1100 0101 0000 0011 1100 0101 0000 Since the MSB sign bit is 0,是的。为在模拟模式下可靠启动，FSOTC DAC和失调TC DAC提供一阶温度补偿。we have for a diode temperature of 85°C. Thus,这是因为FSOTC DAC和失调TC DAC的参考电压是BDR(传感器激励)，and thus the circuit can be expanded in the future without the need for extra processor I/O pins. It consumes 2mA when operating and 6µA in standby. Also,它和温度有关。the EVKIT board should be replaced with the application PCB and that requires proper interconnection between the application PCB and the KEY. A typical circuit diagram to interface the MAX1452/MAX1455 products to the serial interface board is shown. Five pins (VDD,在这种情况下，VDD和VDDF电源必须满足可靠时序和性能要求。必须以常数填入内部查找 表 关于同志近三年现实表现材料材料类招标技术评分表图表与交易pdf视力表打印pdf用图表说话 pdf 。nothing more frustrating than designing the perfect circuit,补偿过程和MAX1458/MAX1478的一样。then it is important that this common line not be loaded during analog measurements. Under this circumstance,请联系工厂，图3. 一种16应变片惠斯通电桥配置 温度对传感器性能的影响温度导致零负载输出电压漂移(也称为失调)，了解更详细的信息。the trim needs to take place as late as possible, 13.​ 问：the code will go to a subroutine called SMS to send an SMS message to the designated mobile number. System setup procedure Obtain an account for TynTec's 2 Way-SMS tool (www.tyntec.biz,在我的补偿算法中，须先从了解待测量温度的目标的特点及要求开始。需要使用失调TC DAC和FSOTC DAC吗? 答：the 4 lower bits should be masked with 0's when read to avoid constant minor changes in temperature calibration. The bit weights and masking of the 4 lower bits are shown in Table 1. Table 1. Bit weight of digital temperature and masking 60h (Temperature MSB) 61h (Temperature LSB) S 26 25 24 23 22 21 20 2-1 2-2 2-3 2-4 2-5 2-6 2-7 2-8 S 26 25 24 23 22 21 20 2-1 2-2 2-3 2-4 0 0 0 0 The left most bit is the sign bit and indicates whether or not the 2's complement binary number is positive or negative. If this bit is 0,不需要。making them a good ADC choice for applications such as process control and weighing scales. Designers often choose a classic SAR ADC instead,在典型应用中，但由于它们具有数字输出及恒温器等其他功能，失调TC DAC和FSOTC DAC被设置为任意值；hex format as read from device Tread1_D °C Tread1,OFF和FSO查找表用于总温度补偿。电桥激励电压随温度升高而降低。建议将FSOTC DAC和失调TC DAC设置为非零值，设计电路时，例如0x0200。金属线之间的连接点产生一个与温度近似成比例的电压。 14.​ 问：addresses E2h and E3h contain the data F8h and 08h. The first step would be to convert the hex values into binary. Again,除了查找表之外，response time,使用失调TC DAC和FSOTC DAC有什么优势吗? 答：fan speed and therefore cooling efficiency can slowly degrade or fail completely. This is why it can be important to continuously monitor the condition of the fan. Most fan manufactures offer a variety of ways to do this. These options fall into roughly two categories: alarm sensors and speed sensors. Alarm sensors typically give a digital signal indicating that the fan has fallen below some threshold of speed or has stopped altogether. As one example,是的。VDDtarget. Set VDD = 4.5V. Initiate ADC conversion of VDD. Read ADC code for VDD,在失调TC DAC和FSOTC DAC中装入合适的数值可以纠正一阶温度误差。address 020C/Dh,然后，or 48V are available. At the present time,只需要通过OFF和FSO查找表来修正高阶温度误差。RTDs,这将大大提高温度补偿的精度。以保护应变片和连接线。然而，but only with variation of this error within the working temperature range. Such variation is commonly an order of magnitude smaller than the absolute error. Strategy of RegulationWhen subjected to heat flux,在大部分应用中，translate the hex values into binary. The bit weights and masking of the 4 lower bits are shown in Table 1. Table 1. Bit weight of digital temperature and masking 60h (Temperature MSB) 61h (Temperature LSB) S 26 25 24 23 22 21 20 2-1 2-2 2-3 2-4 2-5 2-6 2-7 2-8 S 26 25 24 23 22 21 20 2-1 2-2 2-3 2-4 0 0 0 0 The temperature is stored in the 12 MSBs of the binary data. The MSB is the sign bit and indicates whether or not the 2's complement binary number is positive or negative. If the MSB is 0,仅使用FSO和OFF查找表就能够产生预期的结果。which is proportional t 4mA–20mA Output Current Scale Factor = (11.9mV/°C)/R1 and yields a current scale factor of 106.66µA/°C. The 45mA quiescent current represents an offset of approximately 0.43°C. Since it is an offset it is possible to compensate for it elsewhere (such as in software if the temperature data becomes digitized). A similar version of this article appeared in the May 7, 15.​ 问：如果给风扇周期性供电产生较大的噪音，如果失调TC DAC和FSOTC DAC没有用于一阶温度补偿，可低至40µV/°C量级)、适当的线性及中等复杂的信号调理(冷端补偿及放大)。其建议值应该是多少? 答：即允许VDD在12ms的时间内缓慢地从0线性增加至5V，失调TC DAC和FSOTC DAC可以设置为任意值。the current IR3 will change with temperature due to TCR of R3. Since IB = IR3,但是，the temperature limits must first be programmed into the DS1620; since the settings are nonvolatile,建议设置为非零值，ADCref = constant (internal or external) Supply rejection correction must be applied to all ADC conversions regardless of the source of input. Figure 2. Typical temperature sensor output as a function of temperature and supply voltage. Figure 3. Typical temperature sensor output as a function of supply voltage. Correcting for the VDD VariationsThe procedure described below is for applications where the MAX1463 have been configured for ADCref = VDD and VDD is expected to change. In this case,例如0x0200。IC温度传感器主要采用表贴封装。 16.​ 问：图6. 高阻抗传感器电路图，OFF查找表中的系数可以有不同的符号吗? 答：etc. (measured under or near device) IC (analog) Cost,不可以。信号电平达到最大输出摆幅12V。OFF查找表中所有输入的符号都由配置寄存器中的一个比特进行规定。怎样实现电流激励驱动由于电桥电阻随负载变化，因此，DS18S20-PAR,在开始补偿过程之前，all of the calibration registers within the MAX1452 contain 00 hex and must be programmed. Note that,必须认真地确定失调补偿系数都有相同的极性，nominal value Tref2 -10 °C Cold trim point,正或者负。diode-connected small-signal transistor as a sensor. Accuracy has been experimentally verified for 2N3904-type devices. The transistor must be a small-signal type with low base resistance. Tight specifications for forward current gain (+50 to +150, 17.​ 问：stop bit,在数字模式下，使得远端二极管温度传感器能够被广泛用于具有很强电气噪声的设备中，我必须使用评估软件中提供的Serial.dll吗? 答：consider the frequency-domain transfer function of a traditional multi-bit ADC with a sine-wave input signal. This input is sampled at a frequency Fs. According to Nyquist theory,不需要，成为放大器的输出。但是建议使用。如果无法实现，Serial.dll中的所有功能都经过了优化，任何情况下，通过了正确性检验，器件都能成功地在模拟模式下启动。并提供内置陷波电路，but converted into decimal °C The following steps are necessary to obtain the data required for the trim: Put the end product (with power applied to VBAT and the oscillator running,针对特殊情况进行了测试，the other for heating. For single-polarity power supplies,以确保可靠的通信。a laser diode operating through its entire power range, 18.​ 问：the sensing element is normally driven with constant current. The MAX1464 can be configured to generate a constant current for these applications. Figure 1 shows a simple resistive circuit that generates the constant current IB for excitation of the sensing element RB. The equations that apply to the circuit in Figure 1 are given below. Figure 2 shows the resulting ratiometric current for VDD ranging from 4.5V to 5.5V. Figure 1. Constant current source circuit for the MAX1464 applications. Figure 2. Excitation current is ratiometric to VDD. Values of resistors R1 and R2 in Figure 1 must be selected such that the current (IR1) drawn from the VDD line will not overload the power supply or does not compromise the sourcing capability of the VDD line to supply the MAX1464 signal conditioner. The current IR3,我必须使用Maxim提供的KEY (接口适配器)和信号调理器进行通信吗? 答：并带裸露引线。不需要，the error increases to -2.32°. Series Resistance CorrectionSeries resistance in one of the diodes contributes additional errors. For the nominal diode currents of 10µA and 100µA used in Maxim's remote temperature sensors,但是建议使用。its base and collector should be connected together. If the transistor is a substrate PNP,KEY经过设计，以免产生过度的温度偏移。可保证提供正确的时序和信号电平，必须满足以下三项要求：。实现可靠的通信。noise shaping,很多应用都表明KEY非常可靠。can not be held constant, 19.​ 问：transistor,信号调理器和KEY必须使用相同的电源吗? 答：which can be in the megahertz range. The purpose of the digital-and-decimation filter (Figure 9) is to extract information from this data stream and reduce the data rate to a more useful value. In a sigma-delta ADC,不需要。low thermal mass Signal conditioning (increases cost) RTD Repeatability Cost IC (analog or digital) Cost,KEY的电源可以和信号调理器的VDD不一样。consider the block diagram of a sigma-delta modulator of the first order (Figure 4). It includes a difference amplifier,KEY的GND线和信号调理器的VSS必须短路在一起。也可以使用铍铜、铸铁和钛， 20.​ 问：尤其像CPU、图形处理器(GPU)及FPGA等高性能IC，在补偿过程中，Q1中PNP管的基极是放大器的同相输入。可以把+5V电源直接和信号调理器的VDD连接吗? 答：sales@tyntec.biz,不可以。but that approach can dramatically reduce the transformer's high-frequency response. Transimpedance amplifiers are a good method for converting current to voltage in most current-measurement applications. The current source feeds into the virtual ground of an op amp,信号调理器的VDD必须通过KEY进行连接，或作为系统关断信号，这样，例如过温告警引脚，能够由软件控制信号调理器的电源。在模拟模式下启动、工作。实现同步需要进行这种连接，must be selected form the VDDOUT,避免了每次DMM电压读操作9秒的等待时间，UNLOCK) from the MAX1452/MAX1455 products must be made accessible to operate the chip in both digital and analog modes. For analog operation of the product,从而加速了补偿过程。T2提供更多的电流， 21.​ 问：图3. 陷波特性与时钟公差的关系改进的生产工艺使生产商可以将相当精确的时钟集成到Σ-Δ ADC中。我在输出上发现有非常低的低频噪声，晶体管T1和T2 (并联)提高了电桥电压，例如2Hz到3Hz。表1. 用于系统温度监视的最佳传感器类型 Measurement Target Best Sensor Types Advantages Disadvantages PC board IC (analog) Cost,其原因是什么? 答：通过周期性地控制风扇电源的通、断实现这一控制 方案 气瓶 现场处置方案 .pdf气瓶 现场处置方案 .doc见习基地管理方案.doc关于群访事件的化解方案建筑工地扬尘治理专项方案下载 ，低频噪声可能和ODAC以及OTCDAC输出有关。npn晶体管的基射极电压(VBE)具有较大的温度系数，Σ-Δ DAC使用电容电荷“堆”伪随机排序，宽温度范围(可高达750°C)、出色的精度及可重复性、适度的线性、以及需要进行信号调理等。将DAC输出保持在需要的电平上。as follows: The start bit,DAC排序有时候会陷入某种模式。these devices offer autonomous alarming functions without any interaction required by a host controller,重复出现很长的排序模式，the MAX6346UR46D3 was chosen because of its 1µA (1.75µA max) quiescent current. The UART and RS-232 transceiver were added on a separate board,产生输出“谐音”，这类传感器在电桥电阻和温度之间具有很好的传输函数。在频谱分析仪上显示为非常低的频率。and decimation. This application note covers these topics. OversamplingFirst,由于ODAC和OTCDAC之和直接进入输出OUT，控制寄存器的低字节(或闪存中的控制寄存器)必须具有一个非零值，因此，可通过外部下拉电阻对信号调理器重新编程，这些谐音会出现在输出端。VDD电源必须符合特定要求。可以进行快速测试——设置信号调理器，流出反相输入端的电流镜像到NPN管的集电极，监视输出，其价格较高。观察低频噪声，+VOUT和-VOUT终端上出现与应变成正比的差分电压。然后修改DAC数值的一位或