STMicroelectronics E-TDA7478DTR

Overview

E-TDA7478DTR 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 data (RDDA), clock (RDCL), and signal quality (QUAL) for EBU-compliant broadcast reception in automotive and consumer audio systems.

For engineers reviewing the E-TDA7478DTR datasheet, E-TDA7478DTR pinout, E-TDA7478DTR application, or E-TDA7478DTR equivalent, key selection considerations include its 57 kHz filter center frequency, 1187.5 Hz RDCL output timing, internal pull-up/pull-down logic on control pins (FSEL/OSEL/TM/EXTRES), and SO16 package compatibility with legacy TDA7478 designs.

Technical Context

The TDA7478 implements a cascaded antialiasing + 8th-order SC bandpass filter to isolate the 57 kHz RDS subcarrier with ±0.4 kHz center tolerance and 3 kHz 3dB bandwidth. Its digital demodulator uses PLL-based biphase decoding to recover RDDA and RDCL with precise edge alignment - data remains valid for 416.7 µs after each clock transition.

Two oscillator modes are supported: internal quartz (4.332 MHz or 8.664 MHz selectable via FSEL) or external sinusoidal drive (OSEL = GND), enabling EMI reduction with as low as 60 mVpp input. All control inputs feature internal biasing - OSEL has pull-up; FSEL, TM, EXTRES have pull-down.

Key Specifications

Pinout & Package

Package: SO16 (Wide), 10.1–10.5 mm body width, 1.27 mm pitch, JEDEC MS-012 compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with Si4702-C10-GM and TDA7332, E-TDA7478DTR delivers deterministic hardware RDS timing, zero external filter components, and direct CMOS-level RDCL/RDDA outputs - making it optimal for cost-sensitive, timing-critical automotive and consumer FM receivers where MCU resources are constrained.

Availability

E-TDA7478DTR 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 industrial availability.

Supply support for E-TDA7478DTR 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 automotive, industrial, and power management ICs with strong analog and mixed-signal heritage.

E-TDA7478DTR belongs to ST's audio signal processing product line, engineered specifically for EBU-compliant RDS demodulation in cost-sensitive FM radio front-ends with minimal external components.

FAQ

What crystal frequency should I use with E-TDA7478DTR?

E-TDA7478DTR supports two crystal frequencies: 4.332 MHz (default, FSEL open) and 8.664 MHz (FSEL tied to VS). Both are EBU-specified for RDS demodulation. Use 4.332 MHz with C1 = 27 pF and C2 = 47 pF per the datasheet layout guidelines. The 8.664 MHz option halves internal divider load but requires matching C1/C2 values.

Can E-TDA7478DTR operate without a crystal?

Yes - tie OSEL to GND to disable the internal oscillator and drive OSCIN with an external 4.332 MHz or 8.664 MHz sine wave (60–120 mVpp). This mode reduces EMI and eliminates crystal-related layout sensitivity. FSEL still selects frequency, and all other functions remain identical.

How is RDS data timing guaranteed on RDCL and RDDA?

RDCL is a 1187.5 Hz square wave locked to the internal PLL. Data on RDDA changes on either the rising or falling edge of RDCL (decoder-selectable), and remains valid for exactly 416.7 µs after that edge. This fixed hold time ensures reliable sampling by MCUs with variable interrupt latency.

What does the QUAL pin indicate, and how should it be used?

QUAL is an open-drain output that goes high when the internal PLL achieves stable lock on the 57 kHz RDS subcarrier and signal-to-noise ratio exceeds threshold. It should be pulled up to VS with a 10 kΩ resistor and monitored by the host MCU to validate RDS data integrity before parsing RDDA/RDCL streams.