High-speed and high-precision AFE for high-end industrial sensor systems

Renesas Electronics Corporation has extended its 32-bit MCU, providing a new RX device for high-end industrial sensor systems. The latest addition, the RX23E-B, is a 32-bit device from its RX Family offering a high-precision AFE specifically developed for systems that demand fast and accurate analog signal measurements.

The new MCU incorporates a 24-bit Delta-Sigma A/D converter capable of accomplishing a conversion speed of up to 125kSPS (125,000 samples/second) – eight times faster than the existing RX23E-A. It can process accurate A/D conversion while lowering RMS noise to 1/3 (0.18µVrms @1kSPS) compared to the RX23E-A. The RX23E-B enables faster and more precise measurements of critical parameters such as strain, temperature, pressure, flow rate, current and voltage, making it ideal for high-end sensor devices, measuring instruments, and test equipment. In particular, it provides sufficient performance to drive force sensors employed in industrial robots, which often demand measurements as fast as 10µsec (100,000 samples/second). The MCU also lowers the overall system size and the component count by including the AFE and the MCU on a single chip.

"With the addition of the RX23E-B, which comes with an AFE sensor interface, we can now serve a broad range of sensing applications from mid- to high-end systems," said Sakae Ito, vice president of the IoT Platform Business Division at Renesas. "We will continue to extend our product options to meet the growing needs of battery-powered and wireless sensors that demand low power consumption."

"At Meiko Electronics, we have been developing evaluation boards and providing design support to our customers since the RX23E-A product was introduced," said Takatsugu Nemoto, president at Meiko Electronics. "Now, with the introduction of the RX23E-B with a high-speed delta-sigma A/D converter, we anticipate many customers will be able to experience the benefits of its enhanced conversion performance, compact board design and reduced component count."

Like the RX23E-A, the RX23E-B includes a 32MHz RXv2-based CPU with DSP instructions and an FPU and combines the AFE into a single chip using the same fabrication process. It offers new peripheral functions, such as a 16-bit D/A converter, which allows measurement adjustments, self-diagnosis, and analog signal output. The device's +/-10V analog input enables +/-10V measurement with a 5V power supply without needing external components or an additional power supply. An LCD controller with a maximum of 40 SEG x 4 COM and an RTC function are also included.

There has been a significant demand for distributed processing architecture in large-scale instruments that need to control and take measurements of multiple targets, such as robot arms, gas and liquid analysers. In distributed processing design, instead of relying on a dedicated MCU to manage all functions, each function can operate as a separate module, responsible for tasks such as motor control, sensor measurement and temperature control. This modular approach allows for independent development, offers greater design flexibility and simplifies maintenance. As each module needs an MCU for calculations, engineers can develop sensor modules more easily using an MCU with a built-in AFE than by combining a discrete AFE chip and a separate MCU.

The RX23E-B provides a version that supports an A/D conversion data rate of up to 125kSPS and a version that supports up to 31.25kSPS. Both products offer flexible data rate settings ranging from 3.8SPS to the maximum value, allowing users to choose the best balance between data rate and noise for their specific system requirements. The products are available in a 5.5mm square 100-pin BGA package, a 6mm square 40-pin QFN package for compact applications, and wide pin packages ranging from 48- to 100-pin options.