STMicroelectronics TDA7331D

Overview

TDA7331D from STMicroelectronics is a single-chip RDS (Radio Data System) demodulator with integrated 8th-order switched-capacitor bandpass filter, designed for FM radio receivers compliant with EBU specifications. It recovers RDS data (RDDA) and clock (RDCL) at 1187.5 Hz, features 57 kHz bandpass filtering (±3 kHz BW), 20 dB typical gain, and outputs ARI indication and signal quality (QUAL). Used in automotive and consumer FM tuners for traffic announcements and station identification.

For engineers reviewing the TDA7331D datasheet, TDA7331D pinout, TDA7331D application, or TDA7331D equivalent, key selection considerations include its 57 kHz filter center frequency, 1187.5 Hz RDS clock synchronization, internal 4.332 MHz crystal oscillator (with 8.664/17.328 MHz options), ARI/QUAL logic-level outputs, and SO20/DIP20 package compatibility.

Technical Context

The device implements a cascaded antialiasing + 8th-order SC bandpass filter for precise 57 kHz RDS signal extraction, followed by a bipolar-phase decoder and PLL-based 1187.5 Hz clock recovery. All filtering and demodulation are fully digital and require no external passive components beyond crystal and load capacitors.

It supports three selectable oscillator frequencies via FSEL pin (4.332/8.664/17.328 MHz), and allows external clock injection via OSCIN when OSEL is grounded. Output timing guarantees 416.7 µs data validity window relative to RDCL edge transitions under PLL lock.

Key Specifications

Pinout & Package

Available in SO20 (13 mm × 7.6 mm, 1.27 mm pitch) and DIP20 (25.4 mm × 8.5 mm) packages. Both variants share identical pin functions and thermal resistance (R_{th j-amb} = 200 °C/W for SO20, 100 °C/W for DIP20).

Key Features

Applications

Equivalent & Alternatives

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

Compared with Si4702-C10 and TEA5767HN, the TDA7331D delivers deterministic analog-filter-first RDS recovery with hardware-validated 57 kHz selectivity and dedicated status outputs-ideal for safety-critical or high-reliability tuner designs where firmware dependency and filter variability must be minimized.

Availability

TDA7331D is available at Aetrix Electronics and suitable for automotive FM tuners, consumer stereo receivers, portable radios, and broadcast monitoring equipment requiring stable component supply and legacy design continuity.

Supply support for TDA7331D 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 analog, mixed-signal, power, and microcontroller solutions for industrial, automotive, and consumer markets.

The TDA7331D belongs to ST's audio signal processing product line, engineered specifically for high-fidelity, EBU-compliant RDS demodulation in analog FM receiver architectures with minimal external component count.

FAQ

What crystal frequencies does the TDA7331D support?

The TDA7331D supports three crystal frequencies: 4.332 MHz (FSEL open), 8.664 MHz (FSEL tied to VS), and 17.328 MHz (FSEL pulled to VS via 100 kΩ resistor). The internal oscillator divider automatically adapts to each frequency, maintaining correct RDS timing. External clock injection is also supported when OSEL is grounded.

How is RDS data synchronized to the RDCL output?

RDS data (RDDA) is edge-aligned to the 1187.5 Hz RDCL clock under PLL lock. Data remains valid for exactly 416.7 µs after each rising or falling clock transition-whichever edge the downstream decoder uses. This fixed hold time simplifies firmware sampling without requiring dynamic edge detection.

What is the function of the QUAL and ARI pins?

QUAL outputs logic-high when RDS signal quality meets minimum SNR and PLL lock criteria. ARI outputs high when Attention Request Indicator is present-either alone or combined with RDS-and goes low only when pure RDS (no ARI) is detected. Both are CMOS-compatible active-high status signals.

Can the TDA7331D operate without an external crystal?

No-the TDA7331D requires either a 4.332/8.664/17.328 MHz crystal (OSEL open or to VS) or an externally generated sine wave (OSEL grounded). The oscillator section is not optional; it provides the master timing reference for all filtering, PLL, and demodulation functions.