HC55185 Intersil Corporation, HC55185 Datasheet - Page 15

• Manufacturer Part Number: HC55185
• Description: VoIP Ringing SLIC Family
• Manufacturer: Intersil Corporation

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.
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.
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.
RING
FIGURE 13. EXTERNAL RELAY SWITCHING
TIP
FIGURE 14. TEST LOAD SWITCHING
+5V
RELAY
SW+
SW-
LOAD
TEST
4-15
SW+
SW-
SWC
SWC
HC55185
Basic Application Circuit
U1 - Ringing SLIC
R
R
R
R
R
C
C
C
C
D
R
Standard applications will use
values are application dependent and will be determined by
protection requirements.
Design Parameters: Ring Trip Threshold = 76mA
Hook Threshold = 12mA, Loop Current Limit = 24.6mA, Synthesize
Device Impedance = (3*66.5k
protection resistors, impedance across Tip and Ring
terminals = 599 . Transient current limit = 95mA.
TABLE 4. BASIC APPLICATION CIRCUIT COMPONENT LIST
TL
RT
SH
IL
S
RX
DC
PS1
PS2
1
P1
V
CC
, R
, C
, C
FIGURE 15. HC55185 BASIC APPLICATION CIRCUIT
, C
COMPONENT
P2
RS
FB
R
PS3
R
P2
P1
, C
C
C
R
R
C
PS3
R
R
C
RT
RT
SH
POL
TX
TL
IL
C
DC
PS2
, C
C
RT
PS1
TIP
RING
SW+
SW-
RTD
RD
ILIM
CDC
POL
TL
, C
AGND
VCC VBL VBH
POL
HC55185
U
1N400X type with breakdown > 100V.
1
HC55185
49 per side. Protection resistor
/400 = 498.8 , with 49.9
VALUE
18.7k
23.7k
49.9k
71.5k
66.5k
0.47 F
BGND
4.7 F
0.1 F
0.1 F
BSEL
SWC
ALM
VRX
VRS
VTX
VFB
DET
-IN
E0
F0
F1
F2
D
1
R
S
TOL
20%
20%
20%
20%
N/A
1%
1%
1%
1%
1%
PEAK
C
C
C
C
RX
RS
TX
FB
, Switch
RATING
>100V
0.1W
0.1W
0.1W
0.1W
0.1W
100V
10V
10V
N/A