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78P2342JAT-IGT 参数 Datasheet PDF下载

78P2342JAT-IGT图片预览
型号: 78P2342JAT-IGT
PDF下载: 下载PDF文件 查看货源
内容描述: [PCM Transceiver, 1-Func, PQFP100, LQFP-100]
分类和应用: PC电信电信集成电路
文件页数/大小: 36 页 / 366 K
品牌: TDK [ TDK ELECTRONICS ]
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78P2342JAT  
2-port E3/DS3/STS-1 LIU  
with Jitter Attenuator  
The outputs of the data comparators are connected  
to the clock recovery circuits. The clock recovery  
system employs a digital PLL, which uses a line-rate  
reference clock frequency applied to the CKREF pin.  
The jitter tolerance of 78P2342 meets the  
requirements of ITU-T G.823 for E3 rates; the  
requirements of ITU-T G.824, GR-499 (Cat I and II)  
for DS3 rates; and the requirements of GR-253 for  
STS1 rates.  
FUNCTIONAL DESCRIPTION  
The 78P2342JAT contains all the necessary  
transmit and receive circuitry for connection  
between E3, DS3, or STS-1 line interfaces and  
digital Framer/Mapper ICs.  
OPERATING RATE  
The Master Control Register (MSCR) determines  
which mode the device operates in according to the  
table below. The MSL0 pin is also provided for  
mode selection in applications without a serial  
control interface. Upon power-up or reset, the state  
of the MSL0 pin is sensed and mapped into the DS3  
and E3 register bits representing the appropriate  
mode of operation. After power-up/reset, the state of  
the MSL0 pin is ignored.  
Without the Jitter Attenuator, the jitter transfer  
function meets the requirements of GR-499 for  
Category II DS3 interfaces.  
When the Jitter Attenuator is enabled, the  
78P2342JAT meets the requirements of GR-499  
and GR-253 for all categories of DS3/STS1  
equipment and the ETSI TBR-24 requirements for  
E3 rates.  
standards,  
To check conformance with other  
Standard  
MSL0 pin  
DS3 bit  
E3 bit  
please  
refer  
to  
the  
JITTER  
E3  
L
H
Z
Z
0
1
0
1
1
0
0
1
ATTENUATOR TRANSFER FUNCTION section for  
more detailed info.  
DS3  
STS-1  
STS-1  
RECEIVER MONITOR MODE  
When in monitor mode, 20dB of flat gain is applied  
to the incoming signal before it is fed to the receive  
equalizer. This mode is controlled by the MON bit in  
the Mode Control Register.  
RECEIVER OPERATION  
The receiver input is either transformer-coupled or  
capacitor-coupled to the line signal. In applications  
where the highest performance and isolation are  
required, a 1:1 transformer is used in the receive  
path. In applications where isolation is provided  
elsewhere in the circuit, capacitor coupling can be  
used. The receiver input should be line terminated  
externally with a termination resistor.  
The AMI signal first enters an AGC, which has a  
selectable gain range setting. In normal operation,  
the AGC can compensate for signals with up to 6dB  
of flat loss. When Receiver Monitor Mode is  
enabled, the AGC can compensate for a DSX3  
monitor signal with 16 to 20 dB of flat loss. The  
signal then enters a high performance adaptive  
equalizer. The equalizer is designed to overcome  
inter-symbol interference caused by long cable  
lengths. Because the equalizer is adaptive, the  
circuit will work with all square-shaped signals such  
as DS3-high or 34.368 Mbit/s E3. The variable gain  
differential amplifier automatically controls the gain  
to maintain  
a
constant voltage level output  
regardless of the input voltage level.  
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