STMicroelectronics E-TDA7478D

Overview

E-TDA7478D from STMicroelectronics is a single-chip RDS (Radio Data System) demodulator IC designed for FM radio receivers. It integrates an 8th-order switched-capacitor bandpass filter centered at 57 kHz, fully digital RDS demodulation, and a 4.332 MHz crystal oscillator - all without external passive components. It outputs synchronized RDS clock (RDCL, 1187.5 Hz) and data (RDDA), with signal quality indication (QUAL), supporting EBU-compliant broadcast reception in automotive and consumer audio systems.

For engineers reviewing the E-TDA7478D datasheet, E-TDA7478D pinout, E-TDA7478D application, or E-TDA7478D equivalent, key selection considerations include its integrated 57 kHz filter bandwidth (2.5–3.5 kHz), RDS detection sensitivity (1 mV_RMS), reference voltage generation (VREF = VS/2), and dual-crystal frequency support (4.332 MHz / 8.664 MHz) via FSEL/OSEL control pins.

Technical Context

The TDA7478 implements a cascaded antialiasing + 8th-order switched-capacitor bandpass filter to isolate the 57 kHz RDS subcarrier with ±4 kHz rejection ≥22 dB and 38/67 kHz attenuation ≥60/45 dB. Its demodulator uses PLL-based biphase decoding to recover RDDA and RDCL with precise edge-aligned timing (data valid 416.7 µs post-clock transition).

Oscillator control is configurable: FSEL selects between 4.332 MHz and 8.664 MHz crystals; OSEL enables internal oscillator (open/V_S) or external sinusoidal drive (GND), reducing EMI with input amplitude as low as 60 mV_PP. All digital logic inputs feature internal pull-up (OSEL) or pull-down (EXTRES, FSEL, TM) resistors.

Key Specifications

Pinout & Package

Package: SO16 (Wide), 10.1–10.5 mm × 7.4–7.6 mm body, 1.27 mm pitch, 2.35–2.65 mm height.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar RDS demodulation applications.

Compared with TDA7478AD, E-TDA7478D offers identical functionality in SO16 for easier hand-soldering and legacy layout reuse; versus SI4702-C10-GM, it provides discrete, analog-friendly RDS demodulation without embedded MCU overhead or I²C dependency.

Availability

E-TDA7478D is available at Aetrix Electronics and suitable for automotive infotainment systems, consumer FM tuners, and portable radio receivers requiring stable component supply and long-term EBU RDS compliance.

Supply support for E-TDA7478D 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, specializing in analog, power, and automotive ICs with broad industrial and consumer reach.

E-TDA7478D belongs to ST's audio signal processing product line, engineered specifically for EBU-standard RDS demodulation in cost-sensitive, high-reliability FM radio front-ends.

FAQ

What crystal frequency should be used with E-TDA7478D for standard RDS operation?

E-TDA7478D defaults to 4.332 MHz crystal operation when FSEL is left open. This frequency drives the internal PLL to generate the precise 57 kHz filter clock and 1187.5 Hz RDS data clock. An 8.664 MHz crystal may be used if FSEL is tied to VS, doubling the base oscillator frequency while maintaining identical RDS timing performance.

How is the QUAL output used in system design?

The QUAL pin provides an active-high logic signal indicating valid RDS lock - high when the internal PLL has achieved stable synchronization to the 57 kHz subcarrier and demodulated data meets minimum SNR thresholds. It is intended for direct connection to a microcontroller GPIO to trigger RDS data read cycles or display status indicators without software-intensive signal analysis.

Can E-TDA7478D operate with an externally generated 57 kHz clock instead of a crystal?

No - E-TDA7478D does not accept direct 57 kHz clock injection. However, it supports external sinusoidal drive at 4.332 MHz or 8.664 MHz on OSCIN when OSEL is grounded. This allows ultra-low EMI clocking with amplitudes down to 60 mV_PP, while the internal divider still synthesizes the required 57 kHz and 1187.5 Hz clocks.

What is the purpose of the FILOUT pin, and how is it typically used?

FILOUT provides the analog output of the 8th-order switched-capacitor bandpass filter stage - the filtered 57 kHz RDS subcarrier before digital demodulation. It is rarely used in production but serves diagnostic and test purposes: connecting an oscilloscope to FILOUT verifies filter center frequency, bandwidth, and signal integrity prior to demodulation, aiding debug of weak RDS reception issues.