STMicroelectronics STA308

Overview

STA308 from STMicroelectronics is a multichannel digital audio processor with integrated DDX™ PWM output capability, designed for high-efficiency all-digital amplification systems. It supports 8-channel 24-bit processing at input sample rates from 32 kHz to 192 kHz, provides individual channel volume control (0 to –127 dB in 0.5 dB steps), variable digital gain (0 to +24 dB), and active digital crossover - used in powered loudspeaker systems requiring precise channel mapping and bass management.

For engineers reviewing the STA308 datasheet, STA308 pinout, STA308 application, or STA308 equivalent, key selection considerations include its I²S input/output interface compatibility, DDX™ ternary/binary PWM output mode selection, programmable biquad EQ per channel, AM interference reduction mode, and I²C-configurable clock ratio and de-emphasis settings.

Technical Context

The STA308 implements a 24-bit DSP core with variable oversampling (1×, 2×, or 4×) synchronized to input sample rates up to 192 kHz, enabling consistent internal processing timing across formats. Its signal flow includes configurable channel mapping, per-channel mute/zero-detect auto-mute, and dedicated bass management on Channel 6 using scalable mix outputs.

DDX™ output generation uses selectable ternary or binary PWM modulation with programmable attack/release timing for limiter functionality, while DC blocking high-pass filters and adjustable treble/bass controls operate independently per channel. Clocking is managed via PLL with four selectable input ratios and crystal oscillator support (XTI).

Key Specifications

Pinout & Package

TQFP64 package with exposed thermal pad; 64-pin quad flat pack with 0.5 mm pitch, suitable for automated SMT assembly and thermal management in audio amplifier modules.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar multichannel digital audio processor applications.

Compared with TAS3251 and ADAU1781, the STA308 uniquely delivers 8-channel DDX™ PWM output with hardware-accelerated bass management and AM interference mitigation - making it irreplaceable in high-efficiency, high-channel-count digital amplifier designs requiring EMI resilience.

Availability

STA308 is available at Aetrix Electronics and suitable for home theater AV receivers, powered studio monitors, and automotive infotainment systems requiring stable component supply despite its obsolete status - supported via legacy inventory and controlled lifecycle sourcing.

Supply support for STA308 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 microcontrollers, power management, and analog/mixed-signal ICs for industrial, automotive, and consumer markets.

The STA308 belongs to ST's DDX™ digital audio processor family, engineered specifically for high-efficiency, all-digital amplification architectures - emphasizing low-EMI PWM output, flexible channel routing, and real-time I²C configurability in space-constrained audio systems.

FAQ

What clock frequencies must be applied to the XTI pin for 48 kHz and 192 kHz input operation?

The XTI pin requires an external crystal or clock source at multiples of the input sample rate: 98.304 MHz for 48 kHz and 192 kHz operation (2048× fs), per the MCS[2:0] and IR[1:0] register settings. The PLL locks to this reference to generate internal clocks at 98.304 MHz, enabling consistent 24-bit processing and DDX™ PWM timing across both rates.

How does the zero-detect auto-mute function operate, and what triggers it?

The zero-detect auto-mute activates when any channel receives 2048 consecutive zero-value samples after the channel mapping block - regardless of sample rate. Enabled via ZDE bit in ConfB register, it mutes only the affected channel's output while preserving others, preventing audible pop/click during stream interruptions or source loss.

Can the STA308 drive headphones directly, and what configuration is required?

Yes - Channels 7 and 8 support DDX™ Headphone mode, enabled by setting the HPE bit in ConfA register. This configures differential 3-wire output with optimized slew rate and noise floor for direct connection to headphone amplifiers, distinct from standard DDX™ speaker outputs which require external power stages.

What is the purpose of the MVO pin, and how does it interact with software volume control?

MVO is a hardware override that forces the Master Volume Register to 0x00 (full scale) when pulled high, bypassing all software-set master and channel volume values. It operates independently of I²C writes and remains active until MVO returns low, providing fail-safe volume enablement in safety-critical or boot-up scenarios.