Harman Kardon HK 990/230 Service Manual page 17

DESCRIPTION
The WM8740 is a very high performance stereo DAC
designed for audio applications such as CD, DVD, home
theatre systems, set top boxes and digital TV. The WM8740
supports data input word lengths from 16 to 24-bits and
sampling rates up to 192kHz. The WM8740 consists of a
serial interface port, digital interpolation filter, multi-bit sigma
delta modulator and stereo DAC in a small 28-pin SSOP
package. The WM8740 also includes a digitally controllable
mute and attenuator function on each channel.
The internal digital filter has two selectable roll-off
characteristics. A sharp or slow roll-off can be selected
dependent on application requirements. Additionally, the
internal digital filter can be by-passed and the WM8740
used with an external digital filter.
The WM8740 supports two connection schemes for audio
DAC control. The SPI-compatible serial control port
provides access to a wide range of features including on-
chip mute, attenuation and phase reversal. A hardware
controllable interface is also available.
BLOCK DIAGRAM
MODE ML/I2S MC/DM1
(24) (28)
SCLK (5)
BCKIN (3)
SERIAL
LRCIN (1)
INTERFACE
DIN (2)
WOLFSON MICROELECTRONICS LTD
Lutton Court, Bernard Terrace, Edinburgh, EH8 9NX, UK
Tel: +44 (0) 131 667 9386
Fax: +44 (0) 131 667 5176
Email: sales@wolfson.co.uk
http://www.wolfson.co.uk
24-bit, High Performance 192kHz Stereo DAC
MD/DM0 DIFFHW MUTEB
(27) (26) (6) (25)
CONTROL INTERFACE
MUTE/
ATTEN
DIGITAL
FILTERS
MUTE/
ATTEN
Advanced Information, July 2000, Rev 1.7
FEATURES
•
120dB SNR ('A' weighted mono @48kHz), THD+N: -104dB
@ FS
•
117dB SNR ('A' weighted stereo @48kHz), THD+N: -104dB
@ FS
•
Sampling frequency: 8kHz to 192kHz
•
Selectable digital filter roll-off
•
Optional interface to industry standard external filters
•
Differential mono mode needing no glue logic
•
Input data word: 16 to 24-bit
•
Hardware or SPI compatible serial port control modes:
•
Hardware mode: mute, de-emphasis, audio format
control
•
Serial mode: mute, de-emphasis, attenuation (256
steps), phase reversal
•
Fully differential voltage outputs
APPLICATIONS
•
CD, DVD audio
•
Home theatre systems
•
Professional audio systems
CSBIWO RSTB ZERO MODE8X AGNDR
(23) (22) (21) (4)
SIGMA
MUX DELTA
MODULATOR
SIGMA
MUX DELTA
MODULATOR
(15) (8)
AVDD DVDD AVDDL.
Advanced Information data sheets contain
preliminary data on new products in the
Supplementary data will be published at a
15
WM8740
AVDDR
(10) (9)
WM8740
(11) VMIDR
LOW
(12) VOUTRP
RIGHT
PASS
DAC
FILTER (13) VOUTRN
LOW
(17) VOUTLP
LEFT
PASS
DAC
(16) VOUTLN
FILTER
(18) VMIDL
(20) (19) (14) (7)
AGNDL AGND DGND
preproduction phase of development.
later date.
2000 Wolfson Microelectronics Ltd
.