High-Voltage Monitor Features High Accuracy

Aug. 19, 2002
Many applications call for measuring ac lines or high dc voltages. One common technique uses a large voltage divider followed by a buffer. Another employs an inverting attenuator. The problems associated with both methods stem from uneven power...

Many applications call for measuring ac lines or high dc voltages. One common technique uses a large voltage divider followed by a buffer. Another employs an inverting attenuator. The problems associated with both methods stem from uneven power dissipation in the resistors, poor system accuracy due to resistor mismatch, and a large noise gain.

A third solution yields high-accuracy, high-voltage measurements (Fig. 1). The integrator (OP177) supplies negative feedback around the difference amplifier (AD629), forcing its output to stay at 0 V. The voltage divider on the inverting input sets the common-mode voltage of the difference amplifier to VIN/20. VOUT, the integrator output and the measurement output, sources the required current to maintain the common-mode voltage. R1 and C1 compensate the system to a bandwidth of 300 kHz.

The transfer function is: VOUT = VIN/19. For example, a 400-V p-p input signal will produce a 21-V p-p output.

Figure 2 shows that the measured system nonlinearity is less than 20 ppm over the entire 400-V p-p input range. System noise is about 550 nV/√Hz referred to the input, or around 2-mV peak noise voltage (10 ppm of full scale) over a 300-kHz bandwidth.

Sponsored Recommendations

Board-Mount DC/DC Converters in Medical Applications

March 27, 2024
AC/DC or board-mount DC/DC converters provide power for medical devices. This article explains why isolation might be needed and which safety standards apply.

Use Rugged Multiband Antennas to Solve the Mobile Connectivity Challenge

March 27, 2024
Selecting and using antennas for mobile applications requires attention to electrical, mechanical, and environmental characteristics: TE modules can help.

Out-of-the-box Cellular and Wi-Fi connectivity with AWS IoT ExpressLink

March 27, 2024
This demo shows how to enroll LTE-M and Wi-Fi evaluation boards with AWS IoT Core, set up a Connected Health Solution as well as AWS AT commands and AWS IoT ExpressLink security...

How to Quickly Leverage Bluetooth AoA and AoD for Indoor Logistics Tracking

March 27, 2024
Real-time asset tracking is an important aspect of Industry 4.0. Various technologies are available for deploying Real-Time Location.

Comments

To join the conversation, and become an exclusive member of Electronic Design, create an account today!