- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄2012 > MC33215BE (Freescale Semiconductor)IC SPEAKERPHONE CIRCUIT 42-SDIP PDF資料下載
參數(shù)資料
| 型號(hào)： | MC33215BE |
| 廠商： | Freescale Semiconductor |
| 文件頁數(shù)： | 7/20頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC SPEAKERPHONE CIRCUIT 42-SDIP |
| 標(biāo)準(zhǔn)包裝： | 13 |
| 功能： | 語音切換式揚(yáng)聲電話 |
| 電路數(shù)： | 1 |
| 工作溫度： | -20°C ~ 70°C |
| 安裝類型： | 通孔 |
| 封裝/外殼： | 42-SDIP（0.600"，15.24mm） |
| 供應(yīng)商設(shè)備封裝： | 42-PSDIP |
| 包裝： | 管件 |
MC33215
15
MOTOROLA ANALOG IC DEVICE DATA
ASWD = Switching depth as performed in the
attenuators
To avoid howling, the maximum possible loop gain should
be below 0 dB and preferably below –10 dB for comfort. In a
practical telephone design, both the ABMRX(max) and the
ARXBM(max) will be less than 20 dB thus a switching depth of
50 dB will give a loop gain of less than –10 dB. An optimized
sidetone network is of high importance for handsfree
operation. The better the network matches with the
telephone line the less local feedback and the smaller the
switching range can be.
The amount of gain reduction ASWD obtained by the
duplex controller is set via resistor RSWD according:
A
SWD +
20 log
3.6 x R
SWD
R
REF
2
(dB)
In the typical application the gain reduction will be 50 dB.
To compare the transmit and receive signals with each
other, they have to be monitored. This is done by making a
signal envelope and a background noise envelope via the
CTSE, CTBN capacitors for the transmit channel and via the
CRSE, CRBN capacitors for the receive channel. In Figure 14,
a schematic behavior of the envelopes is depicted which is
equal for both transmit and receive.
The voltage signal at the input is first transferred to a
current via the sensitivity adjust network. Then this current is
led through a diode which gives a logarithmic compression in
voltage. It is this voltage from which the signal envelope is
created by means of asymmetric charge and discharge of the
signal envelope capacitor. The noise envelope voltage then
follows in a similar way. Based on the envelope levels, the
MC33215 will switch to transmit, receive or idle mode
following Table 3. The fact that in receive mode the signal on
the base microphone is greater than it is in case of transmit
mode, due to the coupling of the high loudspeaker signal, is
automatically taken into account.
In the table, two particulars can be found. At first, the set
will go to idle mode if the signals are not at least 4.5 dB
greater then the noise floor, which calculates as a 13 mV
voltage difference in envelopes. This avoids continuous
switching over between the modes under slight variations of
the background noise due to, for instance, typing on a
keyboard. Second, a dial tone detector threshold is
implemented to avoid that the set goes to idle mode in
presence of a continuous strong receive signal like a dial
tone. The dial tone detector threshold is proportional to the
RRSA resistor. In the typical application with RRSA = 3.3 k,
the threshold is at 1.26 mVrms at the input RXI or 20 mVrms
at the line. Line length AGC is of influence on the dial tone
detector threshold, increasing the level depending on the line
current with a maximum of 6.0 dB.
In order to perform a correct comparison between the
signal strengths, the sensitivity of the envelope detectors can
be adjusted via the resistors connected to TSA and RSA.
Based on the above, and on the fact that there is an effective
gain of 20 dB in the transmit monitor, it can be derived that for
stable operation the following two relations are valid:
20 log R
TSA t
20 log R
RSA
–A
BMRX(max) )
20 (dB)
20 log R
TSA u
20 log R
RSA
–A
RXBM(max)
–A
SW )
20 (dB)
By measuring the gains and choosing the RRSA, the limits
for RTSA follow. The choice for the sensitivity resistors is not
completely free. The logarithmic compressors and the
amplifier stages have a certain range of operation and, on the
receive side, the choice for RRSA is given by the desired dial
tone detector threshold. Figure 15 indicates the available
dynamic range for the selected value of the sensitivity
resistors.
Figure 14. Signal and Noise Envelopes
Microphone
Input Signal
1.8 V
Internal
TSA
RTSA
CTSA
TSE
CTSE
CTBN
TBN
VHF
F
re
e
sc
a
le
S
e
m
ic
o
n
d
u
c
to
r,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
n
c
..
.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MC33990DR2 | IC TRANSCEIVER J-1850 BUS 8-SOIC |
| MC34017A-3P | IC PHONE TONE RINGER 500HZ 8-DIP |
| MC34018DWR2 | IC SPEAKERPHONE VOICE SW 28-SOIC |
| MC34118DW | IC VOICE SWITCH SPKPHONE 28-SOIC |
| MC44C401LACR2 | IC STEREO ENCODER MTS 32-LQFP |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MC33218AP | 制造商:Rochester Electronics LLC 功能描述: 制造商:Motorola Inc 功能描述: 制造商:MOTOROLA 功能描述: |
| MC33232D | 功能描述:功率因數(shù)校正 IC Critical Mode PFC RoHS:否 制造商:Fairchild Semiconductor 開關(guān)頻率:300 KHz 最大功率耗散: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Reel |
| MC33232DG | 功能描述:功率因數(shù)校正 IC Critical Mode PFC RoHS:否 制造商:Fairchild Semiconductor 開關(guān)頻率:300 KHz 最大功率耗散: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Reel |
| MC33232DR2 | 功能描述:功率因數(shù)校正 IC Critical Mode PFC RoHS:否 制造商:Fairchild Semiconductor 開關(guān)頻率:300 KHz 最大功率耗散: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Reel |
| MC33232DR2G | 功能描述:功率因數(shù)校正 IC Critical Mode PFC RoHS:否 制造商:Fairchild Semiconductor 開關(guān)頻率:300 KHz 最大功率耗散: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Reel |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。