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SI3225-FQ 参数 Datasheet PDF下载

SI3225-FQ图片预览
型号: SI3225-FQ
PDF下载: 下载PDF文件 查看货源
内容描述: 双PROSLIC®可编程CMOS SLIC / CODEC [DUAL PROSLIC® PROGRAMMABLE CMOS SLIC/CODEC]
分类和应用: 电池电信集成电路
文件页数/大小: 108 页 / 1519 K
品牌: SILICONIMAGE [ Silicon image ]
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Si3220/Si3225  
The Si3220 also can add a dc offset component to the  
ringing signal and detect a ring trip event by monitoring  
the dc loop current flowing once the terminal equipment  
transitions to the off-hook state. Although adding dc  
offset reduces the maximum available ringing amplitude  
(using the same ringing supply), this method is required  
to reliably detect a valid ring trip event when sourcing  
longer loop lengths. The dc offset can be programmed  
from 0 to 64.32 V in the RINGOF RAM address as  
required to produce adequate dc loop current in the off-  
hook state. Depending on the loop length and the ring  
trip method, the ac or dc ring trip detection circuits are  
disabled by setting their respective ring trip thresholds,  
RTACTH or RTDCTH, sufficiently high so that they do  
not trip under any condition.  
VDD  
VCC  
Si3220/  
Si3225  
3 V/5 V Relay  
(polarized or  
non-polarized)  
Relay  
Driver  
Logic  
RRDa/b  
TRD1a/b  
TRD2a/b  
GDD  
Si3225 Ring Trip Detection  
Figure 28. Dual ProSLIC Internal Relay Drive  
Circuitry  
The Si3225 implements an external ring trip detection  
scheme when using a standard battery-backed external  
ringing generator. In this application, the centralized  
ringing generator produces an unbalanced ringing  
signal that is distributed to individual TIP/RING pairs. A  
per-channel ringing relay is required to disconnect the  
Si3225 from the TIP/RING pair and apply the ringing  
signal. By monitoring the ringing feed path across a ring  
The internal driver logic and drive circuitry are powered  
by the same V supply as the chip’s main V supply  
DD  
DD  
(VDD1–VDD4 pins). When operating external relays  
from a V  
supply equal to the chip’s V  
supply, an  
DD  
CC  
internal diode network provides protection against  
overvoltage conditions from flyback spikes when the  
relay is opened. Either 3 V or 5 V relays can be used in  
the configuration shown in Figure 28, and either  
polarized or non-polarized relays are acceptable if the  
feed sense resistor (R  
in Figure 31 on page 56) in  
RING  
series with the ringing source, the Si3225 can detect the  
dc current path created when the hook switch inside the  
terminal equipment closes. The internal ring trip  
detection circuitry is identical to that illustrated in  
Figure 27. Figure 31 illustrates the typical external ring  
trip circuitry required for the Si3225. Because of the  
long loop nature of these applications, a dc ring trip  
detection scheme is typically used. The user can  
disable the ac ring trip detection circuitry by setting the  
RTACTH threshold sufficiently high so it does not trip  
under any condition.  
V
and V  
supplies are identical. The input  
CC  
DD  
IN  
impedance, R , of the relay driver pins is a constant  
11 while sinking less than the maximum rated 85 mA  
into the pin.  
If the operating voltage of the relay (V ) is higher than  
CC  
the Dual ProSLIC V supply voltage, an external drive  
DD  
circuit is required to eliminate leakage from V to V  
CC  
DD  
through the internal protection diode. In this  
configuration, a polarized relay will provide optimal  
overvoltage  
protection  
and  
minimal  
external  
Relay Driver Considerations  
components. Figure 29 illustrates the required external  
drive circuit, and Table 31 provides recommended  
The Dual ProSLIC devices include up to three  
dedicated relay drivers to drive external ringing and/or  
test relays. Test relay drivers TRD1a, TRD1b, TRD2a,  
and TRD2b are provided in all product versions, and  
ringing relay drivers RRDa and RRDb are included for  
the Si3225 only. In most applications, the relay can be  
driven directly from the Dual ProSLIC with no external  
relay drive circuitry required. Figure 28 illustrates the  
internal relay driver circuitry using a 3 V or 5 V relay.  
values for R  
for typical relay characteristics and V  
CC  
DRV  
supplies. The output impedance, R  
, of the relay  
OUT  
driver pins is a constant 63 while sourcing less than  
the maximum rated 28 mA out of the pin.  
Rev. 1.0  
53