RX23E-A Tiny Board for Digital Loadcell Reference Design

This is a reference design of a digital load cell using an MCU with a high-precision analog front-end (AFE), the RX23E-A. Using the RX23E-A makes an external dedicated AFE unnecessary, thereby miniaturizing the board.

In the digital load cell, a board mounting ADC and MCU, and a load cell are combined into a single unit; accordingly, the board is required to be small. RX23E-A realizes MCU and AFE on a single chip, not requiring an external dedicated AFE, thereby suitable to miniaturize a board. This reference design is a design for a 22mm × 16mm small board that can be combined with a load cell. This tiny board incorporates an ISL3152E RS-485/RS-422 transceiver, as well as the RX23E-A. RX23E-A performs A/D conversion, digital filter processing, calibration, and physical quantity conversion (Voltage to Weight) on a single chip. ISL3152E transmits weight values to host devices with digital communication, such as Modbus. When creating this reference design, we evaluated weight measurement errors by incorporating this small board into a load cell. Non-linear errors of the weight measurement are within ±0.01%FS. Accordingly, it is confirmed that the precision specifications of a general load cell are well satisfied