STV0684 STMicroelectronics, STV0684 Datasheet - Page 21

• Manufacturer Part Number: STV0684
• Description: IC COPROCESSR VC5700/6700 196BGA
• Manufacturer: STMicroelectronics

Specifications of STV0684

• Applications: *
• Mounting Type: Surface Mount
• Package / Case: 196-BGA
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 497-3901

STV0684
3.5
3.5.1
3.5.1.1 Audio ADC description
3.5.1.2 Audio playback description
Audio interface
The STV0684 is a single chip audio-video processor used for every single step of the processing
chain to record, compress, record and playback audio.The STV0684 features a high quality 16-bit
Sigma Delta analog to digital converter including automatic level control and noise gating, as well as
volume control. It also features an ADPCM CODEC to maximize the length of video clips on a given
mass storage media. Finally, the product features a digital to analog converter (PWM followed by
RC filters) to directly address a speaker or buzzer for audio playback.
Description
The audio interface is used for the following functions:
Audio record is performed through a 16 bit Sigma Delta interface while audio playback is done by a
PWM that needs external RC filtering.
A simple audio compression ADPCM with a four to one compression ratio is used to maximize the
length of audio-video clips.
The ADC block contains an analogue Sigma-Delta converter and associated digital filtering. The
ADC block converts an analogue input to a 16-bit value which is then available for the ADPCM
module. This ADC block contains two main blocks, the audio analogue front end and the ADC
engine for digital filtering and control registers.
The purpose of the audio cell is to provide:
The pulse width modulator (PWM) block is split into four main blocks:
The PWM module produces a pulse train with variable width according to the audio sample to be
played. The rate at which individual pulses are produced is controlled by the sample rate control
register. This module can playback audio at different rates within the range [ 8; 48 ] kHz. All values
are generated from a counter clocked at 48MHz.
Audio record
Audio playback
Audio compression (ADPCM 4 to 1)
16 bits delta-sigma ADC
Automatic level control and noise gate
Volume control on ADC
Control registers
FIFO
Pulse width modulator
Piezo buzzer control
Functional Description
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