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PDF WM8739 Data sheet ( Hoja de datos )
| Número de pieza | WM8739 | |
| Descripción | STEREO AUDIO ADC | |
| Fabricantes | Wolfson Microelectronics plc | |
| Logotipo |  |
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WM8739 / WM8739L
Stereo Audio ADC
DESCRIPTION
The WM8739 is a stereo audio ADC. The WM8739 is
designed specifically for portable MP3 audio and speech
players and recorders. The WM8739 is also ideal for MD,
CD-RW machines and DAT recorders.
Stereo line-level audio inputs are provided, along with a
mute and volume function, and master or slave mode
clocking schemes. The device also has a programmable
high pass filter to remove residual DC offsets.
Stereo 24-bit multi-bit sigma delta ADCs are used with
oversampling digital interpolation and digital filters. Digital
audio output word lengths from 16-32 bits and sampling
rates from 8KHz to 96KHz are supported.
The device is controlled via a 2 or 3 wire serial interface.
The interface provides access to all features including
volume controls, mutes, de-emphasis and extensive power
management facilities. The device is available in a small 20-
pin SSOP package.
BLOCK DIAGRAM
FEATURES
• 90dB SNR (‘A’ weighted @ 48kHz) ADC
• Low Power
- 12mW all-on, 1.4mW standby (‘L’ version)
- 41mW all-on, 5.3mW standby (standard version)
• Low Supply Voltages
- 1.8 – 3.6V Analogue Supply (‘L’ version)
- 2.7 – 3.6V Analogue Supply (standard version)
- 1.42 – 3.6V Digital Supply (both versions)
• Input Volume and Mute Controls
• ADC Sampling Frequency: 8KHz – 96KHz
• Selectable ADC High Pass Filter
• 2 or 3-Wire MPU Serial Control Interface
• Programmable Audio Data Interface Modes
- I2S, Left, Right Justified or DSP
- 16/20/24/32 bit Word Lengths
- Master or Slave Clocking Mode
• 20-Pin SSOP or 5x5mm QFN Package Options
APPLICATIONS
• CD, Minidisc and DAT Recorders
• General Purpose Audio Digitisation
AVDD
VMID
AGND
RLINEIN
VOL/
MUTE
+12 to -34.5dB,
1.5dB Steps
LLINEIN
VOL/
MUTE
+12 to -34.5dB,
1.5dB Steps
CONTROL INTERFACE
ADC
ADC
DIGITAL
FILTERS
WM8739
ADCDAT
ADCLRC
BCLK
OSC
DIV2
WOLFSON MICROELECTRONICS LTD
www.wolfsonmicro.com
Advanced Information, September 2001, Rev 2.2
Copyright 2001 Wolfson Microelectronics Ltd.
1 page  
WM8739 / WM8739L
Advanced Information
ELECTRICAL CHARACTERISTICS
Test Conditions
AVDD, DBVDD = 3.3V, AGND = 0V, DCVDD = 3.3V, DGND = 0V, TA = +25oC, Slave Mode, fs = 48kHz, XTI/MCLK = 256fs
unless otherwise stated.
PARAMETER
SYMBOL TEST CONDITIONS
MIN
TYP
MAX
UNIT
Digital Logic Levels (CMOS Levels)
Input LOW level
Input HIGH level
Output LOW
VIL
VIH
VOL
0.7 x VDD
0.3 x VDD
0.1 x VDD
V
V
V
Output HIGH
VOH
0.9 x VDD
V
Analogue Reference Levels
Reference voltage
Potential divider resistance
VVMID
RVMID
AVDD/2
50K
V
Ohms
Input to ADC
Input Signal Level (0dB)
VINLINE
AVDD = 3.3V
1.0 Vrms
0 dB
AVDD = 1.8V
0.316
0.545
Vrms
(WM8739 only)
-10
-5.27
dBV
Signal to Noise Ratio (Note 1,2)
SNR A-weighted, 0dB gain
85
90
dB
A-weighted, 0dB gain
@ fs = 96kHz
90
dB
A-weighted, 0dB gain,
AVDD = 2.7V
88
dB
A-weighted, 0dB gain,
AVDD = 1.8V
76
dB
(WM8739L only)
Dynamic Range (Note 2)
DNR
A-weighted, -60dBV
85
90
dB
Total Harmonic Distortion
THD -1dBV input, 0dB gain
-84 -74 dB
0.006
0.02
%
-10dBV, 0dB gain
-74
dB
0.02 %
ADC channel separation
1kHz input
90 dB
Programmable Gain
1kHz input
-34.5
0
+12 dB
Rsource < 50 Ohms
Programmable Gain Step Size
1.5 dB
Mute attenuation
0dB, 1kHz input
80
dB
Input Resistance
RINLINE
0dB gain
20k 30k
Ohms
12dB gain
10k 15k
Ohms
Input Capacitance
CINLINE
10 pF
Notes
1. Ratio of output level with 1kHz full scale input, to the output level with all zero’s into the digital input over a 20Hz to
20kHz bandwidth using an Audio analyser.
2. All performance measurements done with 20kHz low pass filter, and where noted an A-weight filter. Failure to use such
a filter will result in higher THD+N and lower SNR and Dynamic Range readings than are found in the Electrical
Characteristics. The low pass filter removes out of band noise; although it is not audible it may affect dynamic
specification values.
3. VMID decoupled with 10uF and 0.1uF capacitors (smaller values may result in reduced performance).
AI Rev 2.2 September 2001
5
5 Page 
WM8739 / WM8739L
Advanced Information
DEVICE DESCRIPTION
INTRODUCTION
The WM8739 is a low power analogue to digital converter (ADC) designed for audio recording. Its
features, performance and low power consumption make it ideal for recordable CD players, MP3
players and portable mini-disc players.
The device includes programmable level line inputs, a crystal oscillator, configurable digital audio
interface and a choice of 2 or 3 wire MPU control interface. It is fully compatible and an ideal partner
for a range of industry standard microprocessors, controllers and DSPs.
The WM8739 has low noise line inputs with programmable +12dB to –34.5dB logarithmic volume
adjustments and mute.
The ADC is of a high quality using a multi-bit high-order oversampling architecture delivering
optimum performance with low power consumption. The output from the ADC is available on the
digital audio interface. The ADC includes a digital high pass filter to remove unwanted dc
components from the audio signal.
The design of the WM8739 has given much attention to power consumption without compromising
performance. It includes the ability to power off parts of the circuitry under software control, including
a standby and power off mode.
The device caters for a number of different sampling rates including industry standard 8kHz, 32kHz,
44.1kHz, 48kHz, 88.2kHz and 96kHz.
There are two unique schemes featured within the programmable sample rates of the WM8739:
Normal industry standard 256/384 fs sampling mode may be used. A special USB sampling mode is
also included, whereby all audio sampling rates can be generated from a 12.00MHZ USB clock. The
WM8739’s unique sample rate converter thus allows the user to generate the required sampling rate
clocks from the 12MHz USB clock. The digital filters used for recording are optimised for each
sampling rate used.
The digitised output is available in a number of audio data formats I2S, DSP Mode (a burst mode in
which frame sync plus 2 data packed words are transmitted), MSB-First, left justified and MSB-First,
right justified. The digital audio interface can operate in both master or slave modes.
The WM8739 can generate the system master clock using an on-chip crystal oscillator, or
alternatively it can accept an external master clock from the audio system. All features are software
controlled using either a 2 or 3-wire MPU interface.
LINE INPUTS
The WM8739 provides Left and Right channel line inputs (RLINEIN and LLINEIN). The inputs are
high impedance and low capacitance, thus ideally suited to receiving line level signals from external
Hi-Fi and other audio equipment.
Both line inputs include independent programmable volume level adjustments and mutes. The
scheme is illustrated in Figure 8. Passive RF and active Anti-Alias filters are also incorporated within
the line inputs. These prevent high frequencies aliasing into the audio band or otherwise degrading
performance.
AI Rev 2.2 September 2001
11
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet WM8739.PDF ] | |
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