ST 公司的STA339BWS是 2.1通路数字音频系统方案,集成了数字音频处理,数字放大器控制和FFX功率输出级. STA339BWS是基于ST所有权的完全灵活放大(FFX)处理器,它可配置成工作在三重模式,二元模式,差分二元和相移PWM调制模式. STA339BWS功率部分四个相互独立的半桥,能配置成不同的模式,提供高达2 x 9 W + 1 x 20 W的功率输出.工作电压从4.5 V 到21.5 V.内部取样速率96kHz,可达到24到28位的精度.本文介绍了STA339BWS的主要特性,方框图以及多种应用电路,包括电源,PLL应用,以及立体声BTL模式输出配置电路图.
STA339BWS : 2.1-channel high-efficiency digital audio system
The STA339BWS is an integrated solution of digital audio processing, digital amplifier
control, and FFX-power output stage, thereby creating a high-power single-chip FFX®
solution comprising high-quality, high-efficiency, all digital amplification.
STA339BWS is based on FFX (fully flexible amplification) processor, a STMicroelectronics proprietary technology. FFX is the evolution and the enlargement of the ST ternary technology: the new processor can be configured to work in ternary, binary, binary differential and phase shift PWM modulation schemes.
STA339BWS contains the ternary, binary and binary differential implementations, a subset of the full capability of the FFX processor.
The STA339BWS is part of the Sound Terminal™ family that provides full digital audio
streaming to the speaker, offering cost effectiveness, low power dissipation and sound
enrichment.
The STA339BWS power section consists of four independent half-bridges. These can be
configured via digital control to operate in different modes. 2.1 channels can be provided by two half-bridges and a single full-bridge, providing up to 2 x 9 W + 1 x 20 W of power output.
Two channels can be provided by two full-bridges, providing up to 2 x 20 W of power. The IC can also be configured as 2.1 channels with 2 x 20 W provided by the device and external power for FFX power drive.
Also provided in the STA339BWS are a full assortment of digital processing features. This
includes up to 7 programmable 28-bit biquads (EQ) per channel and bass/treble tone
control. Available presets enable a time-to-market advantage by substantially reducing the amount of software development needed for certain functions. This includes audio preset volume loudness, preset volume curves and preset EQ settings. There are also new advanced AM radio interference reduction modes. Dual band DRC dynamically equalizes the system to provide speaker linear frequency response regardless output power level.
This feature independently processes the two bands, controlling, dynamically, the output
power level in each band and so providing a better sound quality. The serial audio data input interface accepts all possible formats, including the popular I2S format. Three channels of FFX processing are provided. This high-quality conversion from PCM audio to FFX PWM switching waveform provides over 100 dB SNR and dynamic range.
图1.STA339BWS方框图
STA339BWS 主要特性:
■Wide voltage supply range
4.5 V to 21.5 V (operating range)
24 V (absolute maximum rating)
■3 power output configurations
2 channels of ternary PWM (stereo mode) (2 x 20 W into 8 at 18 V)
3 channels - left, right using binary and LFE using ternary PWM (2.1 mode) (2 x 9 W +
1 x 20 W into 2 x 4 , 1 x 8 at 18 V)
2 channels of ternary PWM (2 x 20 W) + stereo lineout ternary
■2.1 channels of 24-bit FFX® 100 dB SNR and dynamic range
■Selectable 32 to 192 kHz input sample rates
■I2C control with selectable device address
■Digital gain/attenuation +48 dB to -80 dB with 0.5 dB/step resolution
■Soft volume update with programmable ratio
■Individual channel and master gain/attenuation
■Two independent DRC configurable as a dualband anti-clipper (B2DRC) or independent
limiters/compressors
■EQ-DRC for DRC based on filtered signals
■Dedicated LFE processing for bass boosting with 0.5 dB/step resolution
■Audio presets:
15 preset crossover filters
5 preset anti-clipping modes
Preset night-time listening mode
■Individual channel and master soft/hard mute
■Independent channel volume and DSP bypass
■Automatic zero-detect mute
■Automatic invalid input-detect mute
■2-channel I2S input data interface
■Input and output channel mapping
■Up to 8 user-programmable biquads per channel with 28-bit resolution
■3 coefficients banks for EQ presets storing with fast recall via I2C interface
■Bass/treble tones and de-emphasis control
■Selectable high-pass filter for DC blocking
■Advanced AM interference frequency switching and noise suppression modes
■Selectable high- or low-bandwidth noise-shaping topologies
■Variable max power correction for lower full-power THD
■Selectable clock input ratio
■96 kHz internal processing sample rate, 24 to 28-bit precision
■Thermal overload and short-circuit protection embedded
■Video apps: 576 x Fs input mode supported
■Fully compatible with STA339BW.
图2.STA339BWS应用电路(电源)
图3.STA339BWS PLL应用电路
图3.立体声BTL模式输出配置电路图
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