参数资料
型号: DS21Q42TN
厂商: DALLAS SEMICONDUCTOR
元件分类: Digital Transmission Controller
英文描述: DATACOM, FRAMER, PQFP128
封装: TQFP-128
文件页数: 43/119页
文件大小: 1309K
代理商: DS21Q42TN
DS21Q42
3 of 119
Functional Description
The receive side framer locates D4 (SLC–96) or ESF multiframe boundaries as well as detects incoming
alarms including, carrier loss, loss of synchronization, blue (AIS) and yellow alarms. If needed, the
receive side elastic store can be enabled in order to absorb the phase and frequency differences between
the recovered T1 data stream and an asynchronous backplane clock which is provided at the RSYSCLK
input. The clock applied at the RSYSCLK input can be either a 2.048 MHz clock or a 1.544 MHz clock.
The RSYSCLK can be a burst clock with speeds up to 8.192 MHz.
The transmit side of the DS21Q42 is totally independent from the receive side in both the clock
requirements and characteristics. Data off of a backplane can be passed through a transmit side elastic
store if necessary. The transmit formatter will provide the necessary frame/multiframe data overhead for
T1 transmission.
Reader’s Note:
This data sheet assumes a particular nomenclature of the T1 operating environment. In each 125 us frame,
there are 24 eight–bit channels plus a framing bit. It is assumed that the framing bit is sent first followed
by channel 1. Each channel is made up of eight bits which are numbered 1 to 8. Bit number 1 is the MSB
and is transmitted first. Bit number 8 is the LSB and is transmitted last. Throughout this data sheet, the
following abbreviations will be used:
D4
Superframe (12 frames per multiframe) Multiframe Structure
SLC–96
Subscriber Loop Carrier – 96 Channels (SLC–96 is an AT&T registered trademark)
ESF
Extended Superframe (24 frames per multiframe) Multiframe Structure
B8ZS
Bipolar with 8 Zero Substitution
CRC
Cyclical Redundancy Check
Ft
Terminal Framing Pattern in D4
Fs
Signaling Framing Pattern in D4
FPS
Framing Pattern in ESF
MF
Multiframe
BOC
Bit Oriented Code
HDLC
High Level Data Link Control
FDL
Facility Data Link
相关PDF资料
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