STMicroelectronics TDA7331DTR

Overview

TDA7331DTR from STMicroelectronics is a single-chip RDS (Radio Data System) demodulator with integrated 8th-order switched-capacitor bandpass filter, operating at 57 kHz center frequency and supporting EBU-compliant FM radio broadcast data recovery. It delivers purely digital RDS demodulation without external components, provides ARI indication and RDS signal quality outputs, and uses low-noise CMOS technology for high RDS demodulation quality in automotive and consumer radio head units.

For engineers reviewing the TDA7331DTR datasheet, TDA7331DTR pinout, TDA7331DTR application, or TDA7331DTR equivalent, key selection considerations include its 57 kHz bandpass filter performance (±4 kHz attenuation ≥18 dB), 1187.5 Hz RDCL clock output timing validity window (416.7 µs), selectable crystal oscillator frequencies (4.332/8.664/17.328 MHz), and dual-mode oscillator control (internal quartz or external drive via OSEL).

Technical Context

The TDA7331DTR implements a cascaded antialiasing + 8th-order SC bandpass filter architecture to precisely isolate the 57 kHz RDS subcarrier, followed by a PLL-based biphase decoder that recovers RDDA and RDCL synchronized to the incoming MPX signal. Its internal 57 kHz PLL locks to the RDS subcarrier and drives a 1187.5 Hz clock divider for bit-synchronous data extraction.

It supports three oscillator configurations via FSEL and OSEL pins: internal 4.332 MHz crystal (default), or 8.664/17.328 MHz crystals with external resistor bias; alternatively, OSEL grounded enables external sinusoidal drive at OSCIN with as low as 60 mVpp input amplitude while retaining FSEL-based frequency scaling.

Key Specifications

Pinout & Package

Package: SO20 (Small Outline, 20-pin, 0.65 mm pitch, 12.6 × 7.5 mm body). Thermal resistance: 200 °C/W (junction-to-ambient).

Key Features

Applications

Equivalent & Alternatives

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

Compared with Si4702-A10, TDA7331DTR offers simpler analog integration and zero-firmware operation; compared with TDA7330B, it delivers superior 57 kHz selectivity and flexible clock sourcing - making it optimal for cost-sensitive, fixed-function RDS front-ends.

Availability

TDA7331DTR is available at Aetrix Electronics and suitable for automotive infotainment systems, consumer FM tuners, and portable radio receivers requiring stable component supply and long-lifecycle support.

Supply support for TDA7331DTR 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 TDA7331DTR belongs to ST's audio signal processing product line, engineered specifically for high-fidelity, low-component-count RDS demodulation in FM radio systems compliant with EBU RDS specifications.

FAQ

What is the function of the OSEL pin on the TDA7331DTR?

OSEL selects the oscillator source: open or pulled to VS enables the internal 4.332 MHz crystal oscillator; pulling OSEL to GND disables the internal oscillator and allows external sinusoidal drive at OSCIN. In external mode, input amplitude can be as low as 60 mVpp, reducing EMI and enabling use with low-power clock sources.

How does the FSEL pin configure the crystal frequency?

FSEL sets the internal clock divider ratio: open circuit selects 4.332 MHz; pulled to VS selects 8.664 MHz; and a 100 kΩ resistor to VS selects 17.328 MHz. This allows one PCB layout to support multiple crystal options without redesign, accommodating regional FM broadcast timing requirements.

What is the timing relationship between RDCL and RDDA outputs?

RDCL is a 1187.5 Hz clock synchronized to the RDS data stream; RDDA changes on either the rising or falling edge depending on internal PLL lock condition. Data remains valid for 416.7 µs after each clock transition, allowing host microcontrollers to sample reliably using either edge-triggered or level-sensitive capture logic.

Can the TDA7331DTR operate without an external crystal?

No - the TDA7331DTR requires either a 4.332/8.664/17.328 MHz crystal connected between OSCIN and OSCOUT, or an external 57 kHz-related sine wave applied to OSCIN when OSEL is grounded. The internal oscillator circuitry is not self-starting without a resonant element or driven signal.