HC55185(2000) View Datasheet(PDF) - Intersil
Part Name
Description
Manufacturer
HC55185 Datasheet PDF : 17 Pages
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HC55185
Uncommitted Switch
Overview
The uncommitted switch is a three terminal device designed
for flexibility. The independent logic control input, SWC,
allows switch operation regardless of device operating
mode. The switch is activated by a logic low. The positive
and negative terminals of the device are labeled SW+ and
SW- respectively.
Relay Driver
The uncommitted switch may be used as a relay driver by
connecting SW+ to the relay coil and SW- to ground. The
switch is designed to have a maximum on voltage of 0.6V
with a load current of 45mA.
+5V
RELAY
SW+
SW-
SWC
FIGURE 13. EXTERNAL RELAY SWITCHING
Since the device provides the ringing waveform, the relay
functions which may be supported include subscriber
disconnect, test access or line interface bypass. An external
snubber diode is not required when using the uncommitted
switch as a relay driver.
Test Load
The switch may be used to connect test loads across Tip
and Ring. The test loads can provide external test
termination for the device. Proper connection of the
uncommitted switch to Tip and Ring is shown below.
TIP
RING
TEST
LOAD
SW+
SWC
SW-
FIGURE 14. TEST LOAD SWITCHING
The diode in series with the test load blocks current from
flowing through the uncommitted switch when the polarity of
the Tip and Ring terminals are reversed. In addition to the
reverse active state, the polarity of Tip and Ring are reversed
for half of the ringing cycle. With independent logic control
and the blocking diode, the uncommitted switch may be
continuously connected to the Tip and Ring terminals.
Basic Application Circuit
CPS1
CPS2
CPS3
D1
RP1
RP2
CRT
RRT
RSH
RIL
VCC
CDC
CPOL
RTL
VCC VBL VBH
VRX
TIP
U1
VRS
HC55185
RING
VTX
SW+
-IN
SW-
RTD
VFB
RD
ILIM
CDC
POL
TL
AGND
SWC
BSEL
E0
F0
F1
F2
DET
ALM
BGND
CRX
CRS
RS CTX
CFB
FIGURE 15. HC55185 BASIC APPLICATION CIRCUIT
TABLE 4. BASIC APPLICATION CIRCUIT COMPONENT LIST
COMPONENT
VALUE
TOL RATING
U1 - Ringing SLIC
HC55185
N/A
N/A
RTL
18.7kΩ
1%
0.1W
RRT
23.7kΩ
1%
0.1W
RSH
49.9kΩ
1%
0.1W
RIL
71.5kΩ
1%
0.1W
RS
66.5kΩ
1%
0.1W
CRX, CRS, CTX, CRT, CPOL 0.47µF
20%
10V
CDC, CFB
4.7µF
20%
10V
CPS1
0.1µF
20%
>100V
CPS2, CPS3
0.1µF
20%
100V
D1
1N400X type with breakdown > 100V.
RP1, RP2
Standard applications will use ≥ 49Ω per side. Protection resistor
values are application dependent and will be determined by
protection requirements.
Design Parameters: Ring Trip Threshold = 76mAPEAK, Switch
Hook Threshold = 12mA, Loop Current Limit = 24.6mA, Synthesize
Device Impedance = (3*66.5kΩ)/400 = 498.8Ω, with 49.9Ω
protection resistors, impedance across Tip and Ring
terminals = 599Ω. Transient current limit = 95mA.
4-15
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