STMicroelectronics ST7538Q

Overview

ST7538Q from STMicroelectronics is a half-duplex FSK power line transceiver IC designed for CENELEC-compliant narrowband PLC networks. It integrates a programmable power line driver, dual linear regulators (5V/3.3V), UART/SPI host interface, carrier/preamble detection, and mains zero-crossing synchronization. Key confirmed parameters: 8 programmable carrier frequencies (60–132.5 kHz), up to 4800 BPS baud rate, 250 µVrms receiving sensitivity, 5 mA quiescent current, and TQFP44 package.

For engineers reviewing the ST7538Q datasheet, ST7538Q pinout, ST7538Q application, or ST7538Q equivalent, this device serves as a complete single-chip FSK modem solution for smart metering, home automation, and energy management systems requiring EN 50065 compliance, programmable voltage/current control, and robust noise immunity on AC mains lines.

Technical Context

The ST7538Q implements a fully integrated analog front-end with dual op-amp-based transmit/receive filtering, PLL-based synchronization recovery, and automatic level control (ALC) with 30 dB dynamic range. Its digital baseband includes a programmable 24/48-bit security checksum register, header recognition (8/16 bit), and configurable timeout and band-in-use detection logic.

It operates in synchronous or asynchronous mode via UART/SPI, supports both 3.3V and 5V digital supplies, and features independent analog (PAVcc/AVdd) and digital (DVdd) power domains. The internal 16 MHz crystal oscillator drives all timing functions, including master clock output (fclock/2, /4, or off) and precise baud rate generation (600–4800 BPS).

Key Specifications

Pinout & Package

TQFP44 (Slug Down) package with exposed thermal pad; 44-pin quad flat pack optimized for thermal dissipation in high-current line driver applications.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar FSK power line transceiver applications.

Compared with ST7537, the ST7538Q adds 4800 BPS capability, 250 µVrms sensitivity, and dual regulators-enabling smaller, more robust designs. Versus AMIS-49587, it trades OFDM flexibility and automotive qualification for lower system cost and simpler power architecture in commercial metering.

Availability

ST7538Q is available at Aetrix Electronics and suitable for smart metering, home automation gateways, streetlight control systems, and industrial energy monitoring requiring stable component supply across long-lifecycle deployments.

Supply support for ST7538Q 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, Switzerland, specializing in microcontrollers, analog ICs, and power management solutions for industrial, automotive, and consumer markets.

The ST7538Q belongs to ST's dedicated Power Line Communication (PLC) transceiver product line, engineered specifically for EN 50065-compliant narrowband FSK communication over AC mains in utility and building automation applications.

FAQ

What is the maximum allowable PAVcc voltage for continuous operation?

The absolute maximum rating for PAVcc is +14 V, but the functional operating range is strictly 7.5 V to 12.5 V per datasheet Section 3.2. Exceeding 12.5 V risks violating UVLO hysteresis and may trigger thermal shutdown; operation above 12.5 V is not characterized and voids specification guarantees.

Can the ST7538Q operate with an external clock instead of a crystal?

Yes - the XIN pin accepts an external CMOS clock signal with 5 V swing and 2.5 V offset (Section 4, Table 4). The device does not require a crystal; however, the external clock must meet duty cycle (40–60%), jitter, and slew rate specifications to ensure stable PLL lock and accurate baud timing.

How is the 250 µVrms receiving sensitivity achieved in practice?

This sensitivity is measured in high-sensitivity mode with optimized receive filter settings and PLL-locked synchronization recovery (Section 4, Table 4). It requires proper PCB layout (separated analog/digital grounds, shielded RAI routing), correct termination of C_PLUS/C_MINUS, and calibration of the internal AGC loop via control register configuration.

Is the ST7538Q RoHS compliant and qualified for industrial temperature range?

Yes - the ST7538Q is RoHS-compliant (per ST's official product documentation) and specified for −40°C to +85°C ambient operation (Section 3.1, Table 2). It uses Multipower BCD5 technology and is qualified per industrial-grade reliability standards, with thermal resistance RthJA ≤ 50 °C/W on standard multilayer PCBs.