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| 型號： | HC5518X |
| 廠商： | Intersil Corporation |
| 英文描述： | () |
| 中文描述： | （） |
| 文件頁數(shù)： | 1/5頁 |
| 文件大?。?/td> | 37K |
| 代理商： | HC5518X |
1
AN9842.1
www.intersil.com or 407-727-9207 | Copyright Intersil Corporation 1999
RSLIC18 is a trademark of Intersil Corporation.
Implementing Tip and Ring Protection Circuitry
For the HC5518X Ringing SLIC Family
Introduction
A very important segment of
the design of
telecommunications
equipment is proving
adequate surge protection
circuitry for the equipment terminals. System designers are
required to protect the system from secondary (let through)
disturbances as identified in GR-1089 - CORE, Issue 2,
Section 4. Developing the protection circuitry solution while
maintaining overall system performance and cost can often
be challenging. This application note describes circuitry
which could be used to meet the GR-1089, Section 4
requirements for the HC5518X family of ringing SLICs.
Basic Protection Circuit Description
Figure 1 illustrates a basic concept for primary and
secondary protection of telecommunications equipment
terminals where ringing SLICs are used. Although the
following discussions focus primarily on second level surge
protection, it is interesting to briefly discuss primary
protection and “l(fā)et through” surges as defined by GR-1089.
Primary surge protection usually consists of a 3 mil carbon
block or gas tube (GDT). These are voltage and current
limiting devices that will “l(fā)et through” surges of up to 2.5kV
peak surge (lightning) and 600V
RMS
(60Hz) power line
cross. Let through surge currents can range from 500A peak
(2
μ
s x 10
μ
s) lightning to 1A (600V
RMS
) power cross.
Consult GR-1089 for additional details concerning let
through surges for secondary protection.
The secondary protection must protect the T and R ports
from the “l(fā)et through” voltages and currents. Although
secondary protection schemes are application dependent,
Figure 1 shows a typical implementation for a single stage
ringing SLIC where through SLIC ringing is used. The circuit
usually consists of fuses, PTCs (poly switch), RFI
capacitors, diode bridges, and TVS devices such as the
Intersil SGT27S10. This combination of protection circuitry
must clamp the T and R ports to ground when a fault
condition is present that exceeds the maximum output
capabilities of the ringing SLIC. When the fault condition
disappears, normal operation must resume.
The “resettable” PTCs are current limiting devices which
increase in resistance when an applied fault condition
exceeds the specified trip limits of the PTC. When the PTC is
“tripped,” it remains in a high impedance state until the fault
is removed. Capacitors C
1
and C
2
provide a low impedance
path to ground for RFI transients. The diode bridge is used to
clamp positive surges to ground and steer negative
transients to the TVS which turns “on” and clamps the T and
R terminals to ground. With the appropriate selection of
these protection components, secondary protection
requirements specified by GR-1089 can be met while
maintaining overall system performance.
Suggested Protection Circuitry for
HC5518x
Utilizing operational specifications provided by the HC5518X
data sheet and the GR-1089 requirements, the circuit
illustrated in Figure 2 can be implemented to protect the
SLIC from secondary surge levels.
FIGURE 1. BASIC PROTECTION CIRCUIT
TIP
RING
RSLIC18
V
BH
(-85V)
SECONDARY PROTECTION
RFI CAPS
PROTECTION
RESISTORS
AND FUSE
EXPOSED
COPPER
PLANT
PRIMARY
PROTECTION
CARBON
BLOCKS OR
GAS TUBES
CROWBAR
CLAMP TVS
0.002
μ
F
100V
0.002
μ
F
100V
0.1
μ
F
100V
Application Note
September 1999
Authors: Richard Whitehead, Dick Tung
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PDF描述 |
|---|---|
| HCPL-0600 | RESISTOR NETWORK |
| HCPL-0601 | HIGH SPEED-10 MBit/s LOGIC GATE OPTOCOUPLERS |
| HCPL-0730R1 | LOW INPUT CURRENT HIGH GAIN SPLIT DARLINGTON OPTOCOUPLERS |
| HCPL-0730 | LOW INPUT CURRENT HIGH GAIN SPLIT DARLINGTON OPTOCOUPLERS |
| HCPL-0731 | LOW INPUT CURRENT HIGH GAIN SPLIT DARLINGTON OPTOCOUPLERS |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| HC5518XEVAL1 | 制造商:Intersil Corporation 功能描述:EVALUATION BOARD FOR RS - Bulk 制造商:Rochester Electronics LLC 功能描述:EVALUATION BOARD FOR RS - Bulk |
| HC5519 | 制造商:HARRIS 制造商全稱:HARRIS 功能描述:SLIC Subscriber Line Interface Circuit |
| HC5519 WAF | 制造商:Harris Corporation 功能描述: |
| HC5519CQ | 制造商:HARRIS 制造商全稱:HARRIS 功能描述:SLIC Subscriber Line Interface Circuit |
| HC5520 | 制造商:HARRIS 制造商全稱:HARRIS 功能描述:CO/PABX Polarity Reversal Subscriber Line Interface Circuit |
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