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AD590LF 数据表(PDF) 8 Page - Analog Devices |
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AD590LF 数据表(HTML) 8 Page - Analog Devices |
8 / 16 page AD590 Rev. E | Page 8 of 16 0.8°C MAX 0.8°C MAX 1.6 –1.6 –0.8 0 0.8 –55 150 TEMPERATURE (°C) 0.8°C MAX Figure 11. Nonlinearity Figure 12 shows a circuit in which the nonlinearity is the major contributor to error over temperature. The circuit is trimmed by adjusting R1 for a 0 V output with the AD590 at 0°C. R2 is then adjusted for 10 V output with the sensor at 100°C. Other pairs of temperatures can be used with this procedure as long as they are measured accurately by a reference sensor. Note that for 15 V output (150°C), the V+ of the op amp must be greater than 17 V. Also, note that V− should be at least −4 V; if V− is ground, there is no voltage applied across the device. 30pF AD707A 100mV/°C VT = 100mV/°C AD590 AD581 V– 35.7kΩ R1 2kΩ 97.6kΩ R2 5kΩ 27kΩ 15V Figure 12. 2-Temperature Trim 2 –2 0 –55 0 150 100 TEMPERATURE (°C) Figure 13. Typical 2-Trim Accuracy VOLTAGE AND THERMAL ENVIRONMENT EFFECTS The power supply rejection specifications show the maximum expected change in output current vs. input voltage changes. The insensitivity of the output to input voltage allows the use of unregulated supplies. It also means that hundreds of ohms of resistance (such as a CMOS multiplexer) can be tolerated in series with the device. It is important to note that using a supply voltage other than 5 V does not change the PTAT nature of the AD590. In other words, this change is equivalent to a calibration error and can be removed by the scale factor trim (see Figure 10). The AD590 specifications are guaranteed for use in a low thermal resistance environment with 5 V across the sensor. Large changes in the thermal resistance of the sensor’s environment change the amount of self-heating and result in changes in the output, which are predictable but not necessarily desirable. The thermal environment in which the AD590 is used determines two important characteristics: the effect of self- heating and the response of the sensor with time. Figure 14 is a model of the AD590 that demonstrates these characteristics. θJC θCA TJ P CCH CC TA + – TC Figure 14. Thermal Circuit Model As an example, for the TO-52 package, θJC is the thermal resistance between the chip and the case, about 26°C/W. θCA is the thermal resistance between the case and the surroundings and is determined by the characteristics of the thermal connection. Power source P represents the power dissipated on the chip. The rise of the junction temperature, TJ, above the ambient temperature, TA, is TJ − TA = P(θJC + θCA) (1) Table 4 gives the sum of θJC and θCA for several common thermal media for both the H and F packages. The heat sink used was a common clip-on. Using Equation 1, the temperature rise of an AD590 H package in a stirred bath at 25°C, when driven with a 5 V supply, is 0.06°C. However, for the same conditions in still air, the temperature rise is 0.72°C. For a given supply voltage, the temperature rise varies with the current and is PTAT. Therefore, if an application circuit is trimmed with the sensor in the same thermal environment in which it is used, the scale factor trim compensates for this effect over the entire temperature range. |
类似零件编号 - AD590LF |
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类似说明 - AD590LF |
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