參數(shù)資料
型號(hào)： WM9712LEFT
廠商： Wolfson Microelectronics
元件分類： Codec
英文描述： AC97 Audio and Touchpanel CODEC
中文描述： AC97音頻編解碼器和觸摸屏
文件頁(yè)數(shù)： 24/78頁(yè)
文件大小： 689K
代理商： WM9712LEFT
WM9712L
Production Data
w
PD Rev 4.0 December 2003
24
MAXIMUM GAIN
The MAXGAIN register sets the maximum gain value that the PGA can be set to whilst under the
control of the ALC. This has no effect on the PGA when ALC is not enabled.
PEAK LIMITER
To prevent clipping when a large signal occurs just after a period of quiet, the ALC circuit includes a
limiter function. If the ADC input signal exceeds 87.5% of full scale (–1.16dB), the PGA gain is
ramped down at the maximum attack rate (as when ATK = 0000), until the signal level falls below
87.5% of full scale. This function is automatically enabled whenever the ALC is enabled.
(Note: If ATK = 0000, then the limiter makes no difference to the operation of the ALC. It is designed
to prevent clipping when long attack times are used).
NOISE GATE
When the signal is very quiet and consists mainly of noise, the ALC function may cause “noise
pumping”, i.e. loud hissing noise during silence periods. The WM9712L has a noise gate function
that prevents noise pumping by comparing the signal level at the input pins (i.e. before the record
PGA) against a noise gate threshold, NGTH. Provided that the noise gate function is enabled (NGAT
= 1), the noise gate cuts in when:
Signal level at ADC [dB] < NGTH [dB] + PGA gain [dB] + Mic Boost gain [dB]
This is equivalent to:
Signal level at input pin [dB] < NGTH [dB]
The PGA gain is then held constant (preventing it from ramping up as it normally would when the
signal is quiet). If the NGG bit is set, the ADC output is also muted when the noise gate cuts in.
The table below summarises the noise gate control register. The NGTH control bits set the noise
gate threshold with respect to the ADC full-scale range. The threshold is adjusted in 1.5dB steps.
Levels at the extremes of the range may cause inappropriate operation, so care should be taken with
set–up of the function. Note that the noise gate only works in conjunction with the ALC function, and
always operates on the same channel(s) as the ALC (left, right, both, or none).
REGISTER
ADDRESS
62h
ALC / Noise
Gate Control
BIT
LABEL
DEFAULT
DESCRIPTION
7
NGAT
0
Noise gate function enable
1 = enable
0 = disable
Noise gate type
0 = PGA gain held constant
1 = mute ADC output
Noise gate threshold
00000: -76.5dBFS
00001: -75dBFS
… 1.5 dB steps
11110: -31.5dBFS
11111: -30dBFS
5
NGG
0
4:0
NGTH(4:0)
00000
Table 10 Noise Gate Control
相關(guān)PDF資料
PDF描述
WM9712LEFV AC97 Audio and Touchpanel CODEC
WM9712LSEFL AC97 Audio and Touchpanel CODEC
WM9712LSEFT AC97 Audio and Touchpanel CODEC
WM9712LSEFV AC97 Audio and Touchpanel CODEC
WME128K8-XXX 128Kx8 CMOS MONOLITHIC EEPROM, SMD 5962-96796
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
WM9712LEFT/RV 制造商:WOLFSON 制造商全稱:WOLFSON 功能描述:AC97 Audio and Touchpanel CODEC
WM9712LEFV 制造商:WOLFSON 制造商全稱:WOLFSON 功能描述:AC97 Audio and Touchpanel CODEC
WM9712LGEFL/RV 功能描述:接口—CODEC STR AC’97 CODEC TP 48-pin TQFP RoHS:否 制造商:Texas Instruments 類型: 分辨率: 轉(zhuǎn)換速率:48 kSPs 接口類型:I2C ADC 數(shù)量:2 DAC 數(shù)量:4 工作電源電壓:1.8 V, 2.1 V, 2.3 V to 5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:DSBGA-81 封裝:Reel
WM9712LGEFL/V 功能描述:接口—CODEC Stereo AC’97 CODEC T/P Interface RoHS:否 制造商:Texas Instruments 類型: 分辨率: 轉(zhuǎn)換速率:48 kSPs 接口類型:I2C ADC 數(shù)量:2 DAC 數(shù)量:4 工作電源電壓:1.8 V, 2.1 V, 2.3 V to 5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:DSBGA-81 封裝:Reel
WM9712LSEFL 制造商:WOLFSON 制造商全稱:WOLFSON 功能描述:AC97 Audio and Touchpanel CODEC
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