HC55171BIM INTERSIL [Intersil Corporation], HC55171BIM Datasheet - Page 5

• Manufacturer Part Number: HC55171BIM
• Description: Low Cost 5 REN Ringing SLIC for ISDN Modem/TA and WL
• Manufacturer: INTERSIL [Intersil Corporation]

The truth table for the internal logic of the HC55171B is
provided in the above table. This family of ringing SLICs can be
configured to support traditional unbalanced ringing and
through SLIC balanced ringing. The device operating states
used by through SLIC ringing applications are loop power
denial and normal feed. During loop power denial, the tip and
ring amplifiers are disabled (high impedance) and the DC volt-
age of each amplifier approaches ground. The SLIC will not
provide current to the subscriber loop during this mode and will
not detect loop closure. Voice transmission occurs during the
normal loop feed mode. During normal loop feed the SLIC is
completely operational and performs all transmission and
supervisory functions.
F1
SENSE 1
SENSE 2
0
0
1
1
SENSE
RING
RING
TF
RF
TIP
26
15
16
R = 108k
HC55171B DEVICE TRUTH TABLE
25
14
F0
0
1
0
1
TF
Loop power Denial Active
Power Down Latch RESET, Power on
RESET
RD Active (unbalanced ringing)
Normal Loop feed
R
+
-
100K
100K
100K
100K
4.5K
4.5K
R
R
R
R
67
RF
+
-
90K
90K
STATE
V
25K
25K
REF
2R
2R
+
+
-
-
TA
R/20
3
R/2
RA
R
R
90K
V
NU
RX
18
17
+2V
VB/2
REF
OUT 1
HC55171B
12
SHD
RTD
+
-
RTI
-IN 1
OP AMP
28
Power Dissipation
Careful thermal design is required to guarantee that the
maximum junction temperature of 150
exceeded. The junction temperature of the SLIC can be
calculated using:
Where T
junction to air thermal resistance (and is package
dependent). The entire term in parentheses yields the SLIC
power dissipation. The power dissipation of the subscriber
loop does not contribute to device junction temperature and
is subtracted from the power dissipation term. Operating at
85
Likewise, the maximum SOIC SLIC power dissipation is
0.92W.
T
J
13
o
=
C, the maximum PLCC SLIC power dissipation is 1.18W.
T
A
FAULT
V
DET
A
GM
+
RING
is maximum ambient temperature and
24
JA
+
-
I
CC
V
I
LIMIT
V
TX
19
CC
RF2
11
THERM
LTD
+
I
BAT
V
CC
2
V
BAT
NETWORK
RDI
BIAS
SH
TSD
GK
RFC
20
–
o
I
C of the device is not
LOOP
AGND
1
2
22
4
5
6
9
7
8
10
21
27
R
LOOP
JA
BGND
ALM
RDO
V
SHD
RTD
TST
RS
F1
F0
BAT
is
(EQ. 1)