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參數(shù)資料
| 型號： | WM8725ED |
| 廠商： | Wolfson Microelectronics |
| 英文描述： | 99dB Stereo DAC |
| 中文描述： | 九九分貝立體聲DAC |
| 文件頁數(shù)： | 5/9頁 |
| 文件大小： | 348K |
| 代理商： | WM8725ED |
Production Data
WM8725
WOLFSON MICROELECTRONICS LTD
PD Rev 2.0 July 2000
5
DEVICE DESCRIPTION
INTRODUCTION
WM8725 is a complete stereo audio 16-bit digital-to-analogue converter, including digital
interpolation filter, multibit sigma-delta with dither, and switched capacitor multibit stereo
DAC and output smoothing filters.
Special functions of mute and de-emphasis are provided, and operation using system clock
of 256fs or 384fs is provided, selection between either clock rate being automatically
controlled. Sample rates (fs) from less than 8ks/s to 96ks/s are allowed, provided the
appropriate system clock is input.
MUTE
DESCRIPTION
Mute is OFF
Mute is ON
0
1
Table 1 Mute Control
A novel multi bit sigma-delta DAC design is used, utilising a 64x oversampling rate, to
optimise signal to noise performance and offer increased clock jitter tolerance.
Internally generated midrail references are used to DC bias output signals, requiring only a
single external capacitor for decoupling purposes.
The device is packaged in a small 14-pin SOIC package, offering pin compatibility with Burr
Brown PCM1725, but with added functionality of a mute input pin, which may be left floating if
unused, or held
‘
low
’
leaving the device operational.
Single 3V to 5V supplies may be used, the output amplitude scaling with absolute supply
level. Low supply voltage operation and low current consumption, and the low pin count small
package, make the WM8725 attractive for many consumer type applications.
DAC CIRCUITS
The WM8725 DACs are designed to allow playback of 16-bit PCM audio or similar data with
high resolution and low noise and distortion. Sample rates up to 96ks/s may be used, with
much lower sample rates acceptable provided that the ratio of sample rate (LRCIN) to
system clock is maintained at the required 256fs or 384fs times.
The DACs on WM8725 are implemented using sigma-delta oversampled conversion
techniques. These require that the PCM samples are digitally filtered and interpolated to
generate a set of samples at a much higher rate than the 96ks/s input rate. This sample
stream is then digitally modulated to generate a digital pulse stream that is then converted to
analogue signals in a switched capacitor DAC. The advantage of this technique is that the
DAC is linearised using noise shaping techniques, allowing the 16 bit resolution to be met
using non-critical analogue components. A further advantage is that the high sample rate at
the DAC output means that smoothing filters on the output of the DAC need only have fairly
crude characteristics in order to remove the characteristic steps, or images, on the output of
the DAC. To ensure that generation of tones characteristic to sigma-delta convertors is not a
problem, dithering is used in the digital modulator and a higher order modulator is used. The
switched capacitor technique used in the DAC reduces sensitivity to clock jitter compared to
switched current techniques used in other implementations.
De-emphasis of 44.1kHz signals may be applied if required.
DEEMPH
0
1
DESCRIPTION
De-emphasis is OFF
De-emphasis is ON
Table 2 De-emphasis Control
The voltage on the CAP pin is used as the reference for the DACs, therefore the amplitude of the
signals at the DAC outputs will scale with the amplitude of the voltage at the CAP. An external
reference could be used to drive into the CAP pin if desired, but a value typically of about midrail
should be used for optimum performance.
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| WM8725ED/R | 制造商:WOLFSON 制造商全稱:WOLFSON 功能描述:99dB Stereo DAC |
| WM8725GED | 功能描述:音頻數(shù)/模轉換器 IC Stereo DAC RoHS:否 制造商:Texas Instruments 轉換器數(shù)量: 分辨率:16 bit 接口類型:I2S, UBS 轉換速率: 信噪比:98 dB 工作電源電壓:5 V DAC 輸出端數(shù)量:2 工作溫度范圍:- 25 C to + 85 C 電源電流:23 mA 安裝風格:SMD/SMT 封裝 / 箱體:TQFP-32 封裝:Reel |
| WM8725GED/RV | 功能描述:音頻數(shù)/模轉換器 IC Stereo DAC RoHS:否 制造商:Texas Instruments 轉換器數(shù)量: 分辨率:16 bit 接口類型:I2S, UBS 轉換速率: 信噪比:98 dB 工作電源電壓:5 V DAC 輸出端數(shù)量:2 工作溫度范圍:- 25 C to + 85 C 電源電流:23 mA 安裝風格:SMD/SMT 封裝 / 箱體:TQFP-32 封裝:Reel |
| WM8725GED/V | 功能描述:音頻數(shù)/模轉換器 IC Stereo DAC RoHS:否 制造商:Texas Instruments 轉換器數(shù)量: 分辨率:16 bit 接口類型:I2S, UBS 轉換速率: 信噪比:98 dB 工作電源電壓:5 V DAC 輸出端數(shù)量:2 工作溫度范圍:- 25 C to + 85 C 電源電流:23 mA 安裝風格:SMD/SMT 封裝 / 箱體:TQFP-32 封裝:Reel |
| WM8726 | 制造商:WOLFSON 制造商全稱:WOLFSON 功能描述:24-bit 192kHz Stereo DAC |
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