STMicroelectronics TDA7479D

Overview

TDA7479D from STMicroelectronics is a single-chip RDS (Radio Data System) demodulator and 57 kHz bandpass filter for FM radio receivers, compliant with EBU specifications. It integrates an 8th-order switched-capacitor bandpass filter, digital RDS demodulation, ARI indication, and RDS signal quality output - all without external components beyond a 4.332 MHz crystal. Used in automotive and consumer FM tuners to extract RDS data streams (RDDA) and clock (RDCL) for display of station name, traffic announcements, and program type.

For engineers reviewing the TDA7479D datasheet, TDA7479D pinout, TDA7479D application, or TDA7479D equivalent, key selection considerations include its integrated 57 kHz filter bandwidth (3 kHz typ.), RDS detection sensitivity (1 mV_rms), ARI/QUAL dual status outputs, and oscillator configuration flexibility via FSEL/OSEL pins for 4.332/8.664/17.328 MHz crystals.

Technical Context

The TDA7479D implements a cascaded antialiasing + 8th-order switched-capacitor bandpass filter centered at 57 kHz (±0.5 kHz), delivering 20 dB gain and >40 dB attenuation at ±4 kHz offset. Its purely digital RDS demodulation section recovers RDDA and RDCL signals synchronized to an internal PLL locked to the 1187.5 Hz RDS subcarrier.

Pin-controlled oscillator mode selection (OSEL) enables either internal crystal drive or low-amplitude external sinusoidal input (≥60 mV_pp), while FSEL configures division ratios for three crystal frequencies. All inputs feature internal pull-up (OSEL) or pull-down (EXTRES, FSEL, TM) resistors, and outputs drive standard CMOS loads with VOH ≥4.0 V / VOL ≤1.0 V at 0.5 mA.

Key Specifications

Pinout & Package

Package: SO16 (ECOPACK® lead-free, wide-body 10.5 mm × 7.6 mm), per Figure 4 in ST document Rev 8.

Key Features

Applications

Equivalent & Alternatives

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

Compared with Si4702 and TDA7332B, the TDA7479D uniquely balances analog front-end compatibility (MPX input), zero-external-filter digital demodulation, and pin-strapped oscillator flexibility - making it optimal for incremental RDS upgrades in existing FM tuner architectures.

Availability

TDA7479D is available at Aetrix Electronics and suitable for automotive infotainment systems, consumer stereo receivers, and portable FM radios requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for TDA7479D 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 automotive, industrial, and consumer ICs with emphasis on analog, power, and microcontroller solutions.

The TDA7479D belongs to ST's audio signal processing product line, designed specifically to simplify RDS implementation in cost-sensitive FM radio systems while maintaining EBU-compliant performance and robustness against RF interference.

FAQ

What crystal frequency and load capacitors are required for standard operation?

The TDA7479D defaults to 4.332 MHz crystal operation when FSEL is left open and OSEL is unconnected. Use C1 = 27 pF and C2 = 47 pF per ST's recommended values. The device supports 8.664 MHz (FSEL to VS) and 17.328 MHz (FSEL to GND) with same C1 value but no C2 required for higher frequencies.

How is RDS data synchronized between RDDA and RDCL outputs?

RDDA and RDCL are edge-aligned per the internal PLL lock condition: data bits are valid for 416.7 µs after each RDCL transition (rising or falling, depending on decoder setup). The timing diagram in Section 3 confirms 4.3 µs setup/hold margins, ensuring reliable latching by external microcontrollers.

Can the TDA7479D operate without a crystal?

Yes - when OSEL is tied to GND, the internal oscillator disables and accepts an external 4.332/8.664/17.328 MHz sine wave at OSCIN. Input amplitude must be 100–150 mV_pp (depending on frequency); this mode reduces EMI and allows shared clock sources in multi-IC systems.

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

QUAL is an active-high signal indicating valid RDS lock: high = stable PLL lock and usable RDDA/RDCL; low = loss of synchronization or insufficient MPX signal level. It should be monitored continuously by the host MCU to gate RDS parsing and trigger reacquisition routines during signal fade or multipath distortion.