**The AD7405BRIZ: A High-Performance Isolated Sigma-Delta Modulator for Precision Current Sensing**

In the realm of industrial automation, renewable energy systems, and motor control, the accurate and safe measurement of electrical current is paramount. The **AD7405BRIZ** from Analog Devices stands as a critical component in meeting this challenge, offering a highly integrated solution that combines precision measurement with robust galvanic isolation. This device is a second-order, **isolated sigma-delta (Σ-Δ) modulator** that converts an analog input into a high-speed, single-bit data stream, enabling high-resolution current sensing in demanding applications.

The core functionality of the AD7405BRIZ revolves around its ability to digitize a differential voltage signal, typically developed across a shunt resistor through which the current to be measured flows. Its **internal digital isolator** provides up to 5.7 kV RMS of isolation for 1 minute, effectively separating the high-voltage bus (where the measurement occurs) from the low-voltage control side (where the data is processed). This isolation is crucial for protecting sensitive microcontroller units (MCUs) and system operators from hazardous voltages and mitigating the impact of ground potential differences and noise.

The **sigma-delta architecture** is key to its high performance. By oversampling the analog input and using noise shaping, the modulator pushes quantization noise to higher frequencies. When this single-bit output stream is processed by a digital filter (often an on-chip sinc filter within an accompanying microcontroller or FPGA), a high-resolution digital word is reconstructed. The AD7405BRIZ supports a maximum sampling rate of 20 MHz, allowing for a high signal bandwidth, which is essential for accurate control loop performance in applications like servo drives and inverter systems.

A significant advantage of the AD7405BRIZ is its **high common-mode transient immunity (CMTI)** of >100 kV/μs. In noisy switching environments, such as those found in power electronics, high voltage swings can occur rapidly. A high CMTI ensures that the modulator's output remains accurate and free from errors during these fast transitions, guaranteeing reliable data integrity. Furthermore, the device exhibits excellent offset and gain error performance, contributing to overall system accuracy.

Typical applications are diverse and critical:

* **Motor Drives:** Precise phase current measurement for field-oriented control (FOC).

* **Solar Inverters and UPS Systems:** DC-link and output AC current monitoring.

* **Industrial Automation:** Current sensing in PLCs and robotic control systems.

* **Power Monitoring:** Enabling intelligent, connected systems for energy management.

In conclusion, the AD7405BRIZ provides a complete, system-level solution for isolated current sensing. By integrating the modulator and isolator into a single package, it reduces design complexity, improves reliability, and saves board space compared to discrete solutions. Its combination of high accuracy, robust isolation, and exceptional noise immunity makes it an indispensable component for designing advanced and safe power conversion systems.

**ICGOODFIND:** The AD7405BRIZ integrates high-resolution sigma-delta modulation and robust galvanic isolation into a single package, **delivering exceptional accuracy and reliability for precision current sensing** in high-noise, high-voltage environments like motor drives and renewable energy systems.

**Keywords:** Isolated Sigma-Delta Modulator, Precision Current Sensing, Galvanic Isolation, Common-Mode Transient Immunity (CMTI), Motor Control