|
|
PDF WM8725ED Data sheet ( Hoja de datos )
| Número de pieza | WM8725ED | |
| Descripción | 99dB Stereo DAC | |
| Fabricantes | Wolfson Microelectronics plc | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de WM8725ED (archivo pdf) en la parte inferior de esta página. Total 9 Páginas | ||
|
No Preview Available !
DESCRIPTION
WM8725 is a high-performance stereo DAC designed for
use in portable audio equipment, video CD players and
similar applications. It comprises selectable normal or I2S
compatible serial data interfaces for 16 to 24-bit digital
inputs, high performance digital filters, and sigma-delta
output DACs, achieving an excellent 99dB signal-to-noise
performance.
The device is available in a 14-pin SO package that offers
selectable mute and de-emphasis functions using a
minimum of external components.
WM8725
99dB Stereo DAC
Production Data, July 2000, Rev 2.0
FEATURES
• Compatible with PCM1725
• 99dB SNR performance
• Stereo DAC with input sampling from 8kHz to 96kHz
• Additional mute feature
• Normal or I2S compatible data format
• Sigma-delta design with 64x oversampling
• System clock 256fs or 384fs
• Supply range 3V to 5V
• 14-pin SOIC package
APPLICATIONS
• Portable audio equipment
• Video CD players
BLOCK DIAGRAM
FORMAT (13)
SCKI (14)
LRCIN (1)
DIN (2)
BCKIN (3)
SERIAL
INTERFACE
DIGITAL
FILTERS
DIGITAL
SIGMA-DELTA
MODULATOR
DIGITAL
SIGMA-DELTA
MODULATOR
WM8725
SWITCHED
CAPACITOR
DAC
SWITCHED
CAPACITOR
DAC
(6) VOUTR
(9) VOUTL
(12) (10)
DEEMPH MUTE
WOLFSON MICROELECTRONICS LTD
Lutton Court, Bernard Terrace, Edinburgh, EH8 9NX, UK
Tel: +44 (0) 131 667 9386
Fax: +44 (0) 131 667 5176
Email: [email protected]
http://www.wolfson.co.uk
(8) (5) (7)
VDD CAP GND
Production Data datasheets contain final
specifications current on publication date.
Supply of products conforms to Wolfson
Microelectronics’ Terms and Conditions.
2000 Wolfson Microelectronics Ltd.
1 page  
Production Data
WM8725
DEVICE DESCRIPTION
INTRODUCTION
DAC CIRCUITS
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
0
1
Table 1 Mute Control
DESCRIPTION
Mute is OFF
Mute is ON
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.
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
DESCRIPTION
0 De-emphasis is OFF
1 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.
WOLFSON MICROELECTRONICS LTD
PD Rev 2.0 July 2000
5
5 Page | ||
| Páginas | Total 9 Páginas | |
| PDF Descargar | [ Datasheet WM8725ED.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| WM8725ED | 99dB Stereo DAC | Wolfson Microelectronics plc |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |