Industrial Market Measurement Instrumentation Benchmarks
Specifically, it is the first digit of the measured value that can be displayed, which can only display positive, negative and 0, 1, so it is called ½ digit, and the other digits can be displayed from 0 to 9, which we call one digit, for example, a six-and-a-half digit digital multimeter can display a range of values from -199,99999 to 199,99999.
This is also the measurement accuracy of the multimeter, which can reach six decimal places of the stall. If you want to measure very small voltage values, you can set the multimeter to 0.2V voltage stall, and with the six-and-a-half-digit measurement accuracy, you can generally measure voltage signals up to 100nV level.
Voltage Measurement Challenges
In today's industrial automation production designs, it is important to ensure that equipment operates under stable operating conditions by measuring voltage. Highly accurate voltage measurement units are required in the system and can also be used as calibrators to ensure that the voltage at the point to be measured is within the normal operating voltage range. This is an essential part of automated production test equipment. Traditional DMMs are a good choice, offering excellent performance and reliability at high resolution.
ADI's six-and-a-half digit digital voltage module solution ("DVM")
According to the market feedback of customer needs, ADI has developed a new six-and-a-half-digit voltage measurement module ADMX3652, the appearance of which is shown in Figure 1, and the main features are as follows:
* ADI's six-and-a-half-digit voltage module is only 77.7mm*46.3mm*20mm in size, which is comparable to the size of an ordinary business card.
* Supports dual-channel voltage measurement with a measurement range of +/-20V, providing manual and automatic adjustment of 20V/2V/0.2V respectively.
* Low noise, high precision, 90-day accuracy better than 25ppm (2V stop)
* ADI's six-and-a-half-digit digital voltage module supports Auto Zero, NPLC, and full-scale correction.
* When using DVM alone, only need to provide 5V/5W power supply can work normally, and through the UART interface control, support SCPI protocol, data rate can be as high as 1KSPS.
Overvoltage protection is provided on the inputs, and it can operate in ambient conditions from 0 to 45°C, making it easy for system integration or customized system measurements.
Figure 1. Appearance of ADI's Six-and-a-half-digit Digital Voltage Module
Voltage Measurement Unit in the Integrated System
ADI launched a six-and-a-half-bit voltage measurement module ADMX3652, small size, only the size of an ordinary business card, with a voltage measurement mode in the DMM, using 20V, 2V and 0.2V three settings, providing 1KSPS data rate and accurate measurement, controlled through the UART interface, support for the SCPI protocol, you can easily realize the efficient, stable and reliable production test measurement design. In addition, the front-end adopts a high impedance input with over-voltage protection, which can better protect the voltage measurement module. When encountering a situation where the input voltage is out of the measurement range, for example, when the input voltage is 30V, the DVM will not be damaged and burned out even though the DVM cannot measure the accurate voltage value normally.
In the system design, the operation of the DVM can be controlled with the help of the system's MCU or FPGA by issuing commands through the UART, thus helping customers to customize the integrated system measurements in order to reduce the cost of system testing, and its working configuration is shown in Figure 2.
Figure 2. Integrated System Design Configuration
Portable High-precision Voltmeter
When connected to a six-and-a-half digit interface board, this high-performance module can be converted into a portable voltmeter, which is operated through a complete graphical GUI, and with the help of a data logger function, each measurement can be efficiently recorded. By converting the data in Excel into a graph, the change in the voltage value of the object to be measured can be clearly seen on the PC. For voltage measurement, since the ADI DVM provides dual-channel voltage measurement, it is only necessary to connect an external shunt resistor, calculate the corresponding current based on the voltage measured in one of the channels, and then multiply it with the voltage measured in the other channel to derive the power consumption of the device to be tested. The operation of this type of evaluation board is shown in Figure 3.
Figure 3. Six-and-a-half Digit Voltage Module Evaluation System
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