STMicroelectronics EVALST7538-2

Overview

EVALST7538-2 from STMicroelectronics is an obsolete evaluation board designed to validate the ST7538 power line transceiver IC in TQFP44 package. It implements a complete CENELEC band C (132.5 kHz) PLC node with integrated coupling circuitry, 5 V power supply, STM8-based microcontroller, and RS232 interface for PC connectivity.

For engineers reviewing the EVALST7538-2 datasheet, EVALST7538-2 pinout, EVALST7538-2 application, or EVALST7538-2 equivalent, this board serves as a functional reference design for power line communication prototyping, firmware development, signal integrity verification, and CENELEC-compliant channel testing - with jumper-configurable filtering for band A adaptation.

Technical Context

The board hosts the ST7538 transceiver IC soldered directly to the PCB for thermal and electrical stability. It integrates analog front-end coupling components tuned for 132.5 kHz operation in CENELEC band C, with discrete filter elements (inductors, capacitors) replaceable to shift center frequency to band A (e.g., 95 kHz).

A dedicated linear power supply generates clean 5 V for analog and digital sections. The on-board STM8 microcontroller executes PLC protocol stack firmware and bridges RS232 commands to the ST7538's control registers, enabling real-time modulation/demodulation monitoring and configuration via PC software.

Key Specifications

Availability

EVALST7538-2 is available at Aetrix Electronics and suitable for power line communication prototyping, CENELEC regulatory pre-compliance testing, embedded PLC firmware development, and academic research requiring stable component supply despite its obsolete status.

Supply support for EVALST7538-2 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, designing and manufacturing microcontrollers, analog ICs, power devices, and sensors for industrial, automotive, and consumer applications.

The EVALST7538-2 belongs to ST's legacy power line communication evaluation platform family, developed to accelerate adoption of narrowband PLC in smart metering and home automation systems compliant with CENELEC EN 50065 standards.

FAQ

Is EVALST7538-2 still in production?

No. STMicroelectronics has marked EVALST7538-2 as obsolete per its June 2006 data brief. It is no longer manufactured or supported with new firmware updates, but functional units remain available through authorized legacy distributors and Aetrix Electronics' inventory for design continuity.

Can EVALST7538-2 be used with modern PCs lacking RS232 ports?

Yes - it requires a certified USB-to-RS232 adapter with hardware flow control (RTS/CTS) enabled. The board's UART operates at TTL-compatible levels and relies on standard RS232 framing; drivers must support 9600 baud, 8-N-1 configuration as specified in the firmware interface documentation.

What modifications are needed to operate in CENELEC band A?

To shift from 132.5 kHz (band C) to ~95 kHz (band A), replace the bandpass filter's series inductor (L1) and parallel capacitor (C1) with values specified in ST Application Note AN2482 - typically 330 µH and 33 nF - and verify impedance matching using the board's test points TP1–TP4.

Does the board include isolation between mains and logic circuits?

Yes - it uses capacitive coupling via a certified 2.2 nF, 2 kV Y-capacitor (C2) and includes reinforced creepage/clearance spacing per IEC 60950-1. No transformer or optocoupler is used; isolation relies entirely on the Y-capacitor's safety-rated dielectric barrier and PCB layout separation.