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SP322CF 参数 Datasheet PDF下载

SP322CF图片预览
型号: SP322CF
PDF下载: 下载PDF文件 查看货源
内容描述: 可编程的V.11 / V.35收发器 [Programmable V.11/V.35 Transceiver]
分类和应用: 线路驱动器或接收器驱动程序和接口接口集成电路
文件页数/大小: 14 页 / 318 K
品牌: SIPEX [ SIPEX CORPORATION ]
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mode range for the V.11 drivers is +7V to -7V  
which is in accordance to the ITU V.11 specifi-  
cation.  
THEORY OF OPERATION  
The SP322 is a programmable V.11 or V.35  
transceiver IC. It contains three driver and three  
receiverswhichcanbeconfiguredtoeitherV.11  
or V.35 physical layer electrical characteristics.  
The transceivers within the SP322 include all  
the necessary termination resistor networks  
required for compliant V.11 and V.35 signals.  
This simplifies serial port designs using V.11 or  
V.35 where the engineer does not have to  
configure V.11 cable termination resistors and  
the V.35 network.  
When in V.35 mode, the drivers provide V.35  
signals compliant to the ITU V.35 electrical  
specification. Specifically, the V.35 driver is  
designedtosupplyadifferentialoutputof±0.55V  
with an offset of less than 0.6V. With Sipex's  
patent-pending V.35 driver design, the driver  
also adheres to impedance measurements such  
asdriveroutputsourceimpedance(100±50)  
anddriveroutputshort-circuitimpedance(150Ω  
±15). Traditional V.35 drivers require a resis-  
tor network to provide the proper V.35 imped-  
ance specifications for the driver outputs. The  
SP322 V.35 driver does this without the aid of  
any external components attached to the driver  
output. Its unique design contains internal  
resistance matching and switching to provide  
compliant V.35 signals.  
The SP322 contains four basic blocks: the  
charge pump, differential drivers, differential  
receivers, termination network circuitry. Each  
block is described in the following.  
Charge–Pump  
The SP322 charge pump is smaller version of  
the Sipex–patented design (U.S. 5,306,954).  
The charge pump still requires four external  
capacitors and uses a four–phase voltage shift-  
ing technique to attain symmetrical 10V power  
supplies. But the pump is only used for provid-  
ing internal biasing for the transceivers and the  
termination circuitry. The VDD and VSS outputs  
provide only 3mA of output current and should  
not be connected to bias other external circuitry.  
Each driver includes an enable pin for added  
convenience. The driver enable pins are low  
active and will tri-state the driver outputs if a  
logic"1"isapplied. Duringthisstate, thedrivers  
are high impedance. The enable pins include a  
pull-down resistor so that the pin can be  
unconnected where the driver will always be  
enabled. Regardless of physical protocol, the  
drivers can operate to at least 10Mbps.  
Recommended charge pump capacitor values  
are 1µF or greater. The internal oscillator pro-  
vides a clock rate for the charge pump which  
typically operates at 15kHz.  
Receivers  
TheSP322hasthreedifferentialreceiverswhich  
are used for either V.11 or V.35. The receivers  
have a 200mV sensitivity and operate over the  
common mode range of +7V to -7V. The  
receiver itself is the same in either V.11 or V.35  
mode. The receiver input termination is config-  
ured differently for each mode (V.11/V.35 pin).  
Drivers  
The SP322 has three differential drivers. There  
are two types of drivers includes within the  
SP322: V.11 drivers and V.35 drivers.  
When configured in V.11 mode, the V.11 driv-  
ers produce a differential output compliant with  
the V.11 and RS-422 electrical specifications.  
This includes the all the DC electrical param-  
eters such as VOC, VT, VOS, etc. The strength of  
the SP322 drivers allow them to also drive  
signals per the RS-485 standard. The VT mini-  
mum of ±1.5V is provided by the driver output  
given a load of 54as opposed to ±2.0V with a  
100loadforRS-422. However, thedriversare  
not intended to operate over the RS-485 com-  
mon mode range of +12V to -7V. The common  
The receivers also include enable pins for con-  
venience. The receiver enable pins are high  
active where a logic "0" will tri-state the re-  
ceiver outputs. During tri-state, the receiver  
inputs are approximately 12k. Any termina-  
tion associated with the operating mode is dis-  
connected during tri-state of that receiver. The  
receiver enable pins have a pull-up resistor that  
allows the pins to be unconnected. The receiver  
will always be active in this case. The differen-  
tial receiver can operate to at least 10Mbps.  
Rev. 7/9/03  
SP322 V.11/V.35 Serial Transceiver  
© Copyright 2003 Sipex Corporation  
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