库卡 1FK7103-5AF71-1EH0 伺服系统

考虑30 V电压连接在AIN+和AIN-之间的情况。从AIN+朝里看，30V电压看到R1(3kΩ)，之后是内部ESD保护二极管，再后面是从AIN3朝外看到的3kΩ电阻与从AIN4朝外看到的3 kΩ电阻并联。忽略内部ESD保护二极管，AIN+与AIN-之间的总电阻为3 kΩ + 3 kΩ|l3 kΩ=4.5 kΩ。因此，流经AD7124-4的电流限值为30V÷4.5 kΩ=6.7 mA。

Consider the case where the 30 V voltage is connected between AIN+ and AIN-. Looking in from AIN+, the 30 V voltage sees R1 (3 kΩ), followed by the internal ESD protection diode, and then followed by the 3 kΩ resistor seen from AIN3 facing out in parallel with the 3 kΩ resistor seen from AIN4 facing out. Ignoring the internal ESD protection diode, the total resistance between AIN+ and AIN- is 3 kΩ + 3 kΩ|l3 kΩ = 4.5 kΩ. Therefore, the current limit flowing through the AD7124-4 is 30V ÷ 4.5 kΩ = 6.7 mA.

所示电路可连接到2线、3线或4线RTD,大可测量3.92kΩ电阻，因此它适用于Pt100和Pt1000RTD。使用电流激励，电阻测量为RTD与3.92kΩ精密基准电阻(RREF)之间的比率式测量结果。所示，RTD测量在AIN1和AIN3之间进行，REFIN1+和REFIN1-用作测量的基准输入。线模式:仅AIN0上的激励有效，设置为250 μA,线模式:AIN0和AIN4上的激励电流均有效，各设置为100μA,线模式:仅AIN0上的激励有效，设置为250 μA。

The circuit shown can be connected to a 2-, 3- or 4-wire RTD and measures up to 3.92kΩ resistance, making it suitable for Pt100 and Pt1000 RTDs.Using current excitation, the resistance measurement is a ratiometric measurement between the RTD and a 3.92kΩ precision reference resistor (RREF). As shown, RTD measurements are made between AIN1 and AIN3, with REFIN1+ and REFIN1- used as reference inputs for the measurements. Line mode: Excitation on AIN0 only is valid and set to 250 μA,Line mode: Excitation current on both AIN0 and AIN4 is valid and set to 100 μA each,Line mode: Excitation on AIN0 only is valid and set to 250 μA.

使用高端电流检测技术。 对于较低的RTD引线电阻值，此技术可降低3线模式下电流失配的影响,基准电阻(RREF)选择为3.92 kΩ，高支持850°C的Pt1000 RTD测量（850°C时RTD电阻为3.9048 kΩ）。 RREF的值必须根据RTD的大预期电阻来选择。 RREF电阻的精度直接影响测量精度，因此，必须使用精密、低漂移电阻。 

High-end current detection technology is used. For lower RTD lead resistance values, this technique reduces the effect of current mismatch in 3-wire mode. The reference resistance (RREF) is selected to be 3.92 kΩ, which is high enough to support Pt1000 RTD measurements at 850°C (RTD resistance of 3.9048 kΩ at 850°C). The value of RREF must be selected based on the large expected resistance of the RTD. The accuracy of the RREF resistor has a direct impact on the measurement accuracy; therefore, precision, low-drift resistors must be used.