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PBL3881QN-T 参数 Datasheet PDF下载

PBL3881QN-T图片预览
型号: PBL3881QN-T
PDF下载: 下载PDF文件 查看货源
内容描述: [Speaker Phone Circuit, PQCC28, PLASTIC, LCC-28]
分类和应用: 电信电信集成电路
文件页数/大小: 16 页 / 219 K
品牌: ERICSSON [ ERICSSON ]
 浏览型号PBL3881QN-T的Datasheet PDF文件第2页浏览型号PBL3881QN-T的Datasheet PDF文件第3页浏览型号PBL3881QN-T的Datasheet PDF文件第4页浏览型号PBL3881QN-T的Datasheet PDF文件第5页浏览型号PBL3881QN-T的Datasheet PDF文件第7页浏览型号PBL3881QN-T的Datasheet PDF文件第8页浏览型号PBL3881QN-T的Datasheet PDF文件第9页浏览型号PBL3881QN-T的Datasheet PDF文件第10页  
PBL 3881  
Functional Description  
Speech control section.  
Transmitter and Receiver  
Channels  
-C  
LS  
+L  
The transmitter and receiver channels  
consist of three amplifying stages each,  
F1, F2, F3 and F4, F5, F6. The inputs  
and outputs of the amplifiers must be ac.  
coupled because they are dc. vise at the  
internal reference voltage (1.9 V) level.  
F1 and F4 are fixed gain amplifiers of 30  
dB and 20 dB respectively, while the rest  
of them are of controlled gain type. The  
gain of F2, F3 as well as F5 and F6 is  
controlled by comparators. The  
21 17  
19  
20  
22  
16  
R
E
+
B
in  
GND  
18  
R
DC  
5
T
xout  
PBL 3881  
14  
CTR  
10  
R
xout  
Control  
comparators receive their information  
partly from the summing point of the  
transmitter, receiver and background  
noise detectors at CMP input and partly  
through the control input, CTR, which  
controls the gain dynamics (0-50 dB).  
Amplifiers F2 and F3 have the maximum  
gain when the transmitter channel is fully  
open, consequently the amplifiers F5 and  
F6 will have minimum gain and vice  
versa. See figure 8. and figure 15.  
+
+
F
3
F
6
15  
4
V
+
F2  
F
5
F
2 in  
11  
13  
12  
3
1
F
4out  
F
1out  
V
Ref  
-T  
xin  
-
-R  
1.9V  
xin  
xin  
F
1
F4  
2
+
T
xin  
+
+
+
R
7
6
8
xDet CMP  
9
The positive input on each channel has  
a high input impedance. It renders a  
good gain precision and noise  
N
T
R
xDet  
Det  
R1  
R5  
R2  
performance when used with low signal  
source impedance. The negative input of  
the receiver channel should be returned  
to ground with a capacitor. The differen-  
tial input of the transmitter channel can  
be used to suppress unwanted signals in  
the microphone supply, see figure 10.  
Also see application 1.  
R6  
R3  
R4  
C1  
+
+
C4  
C3  
C2  
The output of the transmitter channel  
input amplifier (F1) and the input of (F2)  
are made accessible in order to allow  
filtering in the channel. The output of F4  
can be used to implement an optional  
AGC (Automatic Gain Control) system in  
the receiver channel. The maximum dyn-  
amic range of the AGC can be made the  
same as the gain of F4. See figure 11.  
Figure 8. Passive networks setting the speech control function.  
I
F
5
F
2
1
4
3
11  
AGC  
Signal Detectors and  
Comparators  
Ref.  
100k  
100k  
100k  
100k  
+
F
4
F
The signal detectors sense and rectify  
the receiver and microphone signals to  
opposite polarities referenced to the  
internal reference voltage of approx.  
1.9 V. The voltage at RxDet will go  
negative and at TxDet positive in the  
presence of a signal at the respective  
channel input. In the idle (no signal)  
state, the voltage at RxDet ,TxDet and CMP  
is equal to the internal reference voltage  
+
1
2
13  
12  
Rx  
Tx  
V
3.2k  
10k  
16  
V
Txin  
Rxin  
Figure 9. Receive and transmit channel input arrangement.  
6