STA120D

Audio Special Purpose Overview

The STA120D is a monolithic CMOS digital audio interface receiver designed to decode audio data according to AES/EBU, IEC 958, S/PDIF, and EIAJ CP-340/1201 standards. It integrates an RS422 line receiver and a Phase-Locked Loop (PLL) for clock recovery and synchronization. The device operates on a 3.3V supply voltage with a range of 3.0V to 3.6V. It supports input sample frequencies from 25 kHz to 96 kHz and generates a master clock (MCK) at 256 times the sample frequency, up to 25 MHz. The chip features low-jitter clock recovery with jitter attenuation starting at approximately 25 kHz.

Audio Special Purpose Feature Summary

• Supports professional and consumer digital audio formats including AES/EBU, IEC 958, S/PDIF, and EIAJ CP-340/1201.
• Integrates an RS422-compatible differential line receiver with Schmitt trigger hysteresis for noise immunity.
• Provides extensive error reporting via dedicated pins for validity, parity, biphase coding, and PLL lock status.
• Outputs channel status bits directly without requiring microprocessor intervention for critical flags.

Audio Special Purpose Applications

• Digital audio receivers in professional broadcast equipment.
• Consumer audio interfaces such as CD players and home theater systems.
• Audio processing units requiring direct decoding of serial digital audio streams.

Audio Special Purpose Procurement Notes

Verify the package type corresponds to SO28 when sourcing the STA120D variant. Confirm that the application circuit includes the required external loop filter components (330 Ohm resistor and capacitors) connected to the FILT pin for proper PLL operation. Ensure power supplies are regulated within the 3.0V to 3.6V range to maintain specified electrical characteristics.

Audio Special Purpose Selection Notes

Select the STA120D for applications requiring direct decoding of standard digital audio interfaces without complex firmware overhead. It is suitable for designs needing dedicated hardware outputs for channel status and error flags. Consider the available serial port modes (14 formats) to match the target system's data alignment requirements. Verify compatibility with the specific transmission line impedance (75 Ohm or 110 Ohm) using the provided termination circuits.

Audio Special Purpose Part Context

The STA120D is part of the STA120 family of digital audio interface receivers manufactured by STMicroelectronics. It is housed in an SO28 package. This component serves as a bridge between digital audio transmission lines and downstream audio processors or DACs by handling clock recovery and data demultiplexing.

Audio Special Purpose Replacement Considerations

Public confirmed substitute part numbers are not available in the provided documentation. Designers should verify pin-to-pin compatibility and electrical specifications if considering alternative manufacturers' devices.

Audio Special Purpose FAQ

How does the STA120 handle errors during audio data reception?

The STA120 provides an 'Repeat Last Sample' option in normal modes to maintain audio continuity during errors. In special modes, it may output invalid data. Error conditions such as parity violations, biphase coding errors, and loss of PLL lock are signaled via the ERF pin and encoded on the E2-E0 pins.

What is the function of the FILT pin?

The FILT pin connects to the external loop filter components for the internal Phase-Locked Loop (PLL). A 330 Ohm resistor and capacitors (0.47 μF and 15 nF) must be connected between this pin and AGND to stabilize the VCO and achieve low-jitter clock recovery.

Can the STA120 decode both differential and single-ended inputs?

Yes, the integrated RS422 line receiver can decode both differential signals (professional interface) and single-ended signals (consumer interface). External termination resistors (110 Ohm or 75 Ohm) are required based on the input type.