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CMX624P4 参数 Datasheet PDF下载

CMX624P4图片预览
型号: CMX624P4
PDF下载: 下载PDF文件 查看货源
内容描述: V.23 /贝尔202调制解调器 [V.23 / Bell 202 Modem]
分类和应用: 调制解调器电信集成电路电信电路光电二极管
文件页数/大小: 26 页 / 703 K
品牌: CMLMICRO [ CML MICROCIRCUITS ]
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V23 / Bell 202 Modem  
CMX624  
1.6.2 Ring Detector Interface  
Figure 9 shows how the CMX624 may be used to detect the large amplitude Ringing signal received at the  
start of an incoming telephone call.  
The ring signal is usually applied at the subscriber's exchange as an ac voltage inserted in series with one  
of the telephone wires and will pass through either C20 and R20 or C21 and R21 to appear at the top end  
of R22 (point X in Figure 9) in a rectified and attenuated form.  
The signal at point X is further attenuated by the potential divider formed by R22 and R23 before being  
applied to the CMX624 RD input. If the amplitude of the signal appearing at RD is greater than the input  
threshold (Vthi) of Schmitt trigger 'A' then the N transistor connected to RT will be turned on, pulling the  
voltage at RT to V by discharging the external capacitor C22. The output of the Schmitt trigger 'B' will  
SS  
then go high, setting bit 6 (Ring Detect) of the FLAGS Register.  
The minimum amplitude ringing signal that is certain to be detected is:  
( 0.7 + Vthi x [R20 + R22 + R23] / R23 ) x 0.707 Vrms  
where Vthi is the high-going threshold voltage of the Schmitt trigger A (see Section 1.7.1).  
With R20-22 all 470kas Figure 9, then setting R23 to 68kwill guarantee detection of ringing signals of  
40Vrms and above for V  
over the range 3.0 to 5.5V.  
DD  
R20, 21, 22  
R23  
R24  
C20, 21  
C22  
D1-4  
470kΩ  
See text  
470kΩ  
0.1µF  
0.33µF  
1N4004  
Resistors ±1%, capacitors ±20%  
Figure 9 Ring Signal Detector Interface Circuit  
2003 CML Microsystems Plc  
17  
D/624/7