參數資料
型號: AD1846JP
廠商: ANALOG DEVICES INC
元件分類: 消費家電
英文描述: Low Cost Parallel-Port 16-Bit SoundPort Stereo Codec
中文描述: SPECIALTY CONSUMER CIRCUIT, PQCC68
封裝: PLASTIC, LCC-68
文件頁數: 25/28頁
文件大小: 277K
代理商: AD1846JP
AD1846
REV. A
–25–
APPLICAT IONS CIRCUIT S
T he AD1846 Stereo Codec has been designed to require a mini-
mum of external circuitry. T he recommended circuits are shown
in Figures 17 through 25. Analog Devices estimates that the to-
tal cost of all the components shown in these figures, including
crystals but not including connectors, to be less than $10 in the
U.S.A. in 10,000 quantities.
See Figure 1 for an illustration of the connection between the
AD1846 SoundPort Codec and the Industry Standard Architec-
ture (ISA) computer bus, also known as the “PC-AT bus.”
Note that the 74_245 transceiver receives its enable and direc-
tion signals directly from the Codec. Analog Devices recom-
mends using the “slowest” 74_245 adequately fast to meet all
AD1846 and computer bus timing and drive requirements. So
doing will minimize switching transients of the 74_245. T his in
turn will minimize the digital feedthrough effects of the trans-
ceiver when driving the AD1846, which can cause the audio
noise floor to rise.
Industry-standard compact disc “l(fā)ine-levels” are 2 V rms cen-
tered around analog ground. (For other audio equipment, “l(fā)ine
level” is much more loosely defined.) T he AD1846 SoundPort
is a +5 V only powered device. Line level voltage swings for the
AD1846 are defined to be 1 V rms for a sine wave ADC input
and 0.707 V rms for a sine wave DAC output. T hus, 2 V rms
input analog signals must be attenuated and either centered
around the reference voltage intermediate between 0 V and
+5 V or ac-coupled. T he V
REF
pin will be at this intermediate
voltage, nominally 2.25 V. It has limited drive but can be used
as a voltage offset to an op amp input. Note, however, that
dc-coupled inputs are not recommended, as they provide no
performance benefits with the AD1846 architecture. Further-
more, dc offset differences between multiple dc-coupled inputs
create the potential for “clicks” when changing the input mux
selection.
A circuit for 2 V rms line-level inputs and auxiliaries is shown in
Figure 17. Note that this is a divide-by-two resistive divider.
T he input resistor and 560 pF capacitor provides the single-pole
of anti-alias filtering required for the ADCs. If line-level inputs
are already at the 1 V rms levels expected by the AD1846, the
resistors in parallel with the 560 pF capacitors can be omitted.
T he circuit shown in Figure 17 will produce gain/attenuation
step sizes for the auxiliary inputs which are a function of the
programmed gain/attenuation.
5.1k
5.1k
560pF
L_LINE
L_AUX1
L_AUX2
0.33
μ
F
NPO
5.1k
5.1k
560pF
R_LINE
R_AUX1
R_AUX2
0.33
μ
F
NPO
Figure 17. 2 V rms Line-Level Input Circuits
Figure 18 illustrates one example of how an electret condenser
mike requiring phantom power could be connected to the
AD1846. V
REF
is shown buffered by an op amp; a transistor like
a 2N4124 will also work fine for this purpose.
Particular system requirements will depend upon the character-
istics of the intended microphone.
Note that if a battery-powered microphone is used, the buffer
and R
2
s are not needed. T he values of R
1
, R
2
s, and C should be
chosen in light of the mic characteristics and intended gain.
T ypical values for these might be R
1
= 20 k
, R
2
= 2 k
, and
C = 220 pF.
5.1k
1
μ
F
1/2 SSM-2135
OR AD820
L_MIC
V
REF
LEFT ELECTRET
CONDENSER
MICROPHONE
INPUT
5.1k
C
1
μ
F
R_MIC
RIGHT ELECTRET
CONDENSER
MICROPHONE
INPUT
1/2 SSM-2135
OR AD820
1/2 SSM-2135
OR AD820
R
1
C
V
REF
R
1
R
2
R
2
0.33
μ
F
0.33
μ
F
Figure 18. “ Phantom-Powered” Microphone Input Circuit
Figure 19 shows ac-coupled line outputs. T he resistors are used
to center the output signals around analog ground. If
dc-coupling is desired, V
REF
could be used with op amps as
mentioned previously.
1
μ
F
47k
L_OUT
1
μ
F
47k
R_OUT
Figure 19. Line Output Connections
A circuit for headphone drive is illustrated in Figure 20. Drive is
supplied by +5 V operational amplifiers. T he circuit shown ac
couples the line output to the headphones.
HEADPHONE
LEFT
HEADPHONE
RIGHT
L_OUT
R_OUT
470
μ
F
20k
SSM-2135
V
REF
18k
18k
470
μ
F
20k
Figure 20. Headphone Drive Connections
相關PDF資料
PDF描述
AD1849KP Serial-Port 16-Bit SoundPort Stereo Codec
AD1851 16-Bit, 16×Fs PCM Audio DACs(16位,單片PCM音頻D/A轉換器)
AD1892JR Integrated Digital Receiver/Rate Converter
AD1892JRRL Integrated Digital Receiver/Rate Converter
AD1892 Integrated Digital Receiver/Rate Converter(數字音頻接收器/采樣率轉換器)
相關代理商/技術參數
參數描述
AD1846JP-REEL 制造商:Analog Devices 功能描述:
AD1847 制造商:AD 制造商全稱:Analog Devices 功能描述:Serial-Port 16-Bit SoundPort Stereo Codec
AD1847JP 制造商:Rochester Electronics LLC 功能描述:- Bulk
AD1847JP-REEL 制造商:Rochester Electronics LLC 功能描述:- Tape and Reel
AD1847JST 制造商:AD 制造商全稱:Analog Devices 功能描述:Serial-Port 16-Bit SoundPort Stereo Codec