HC55120CM INTERSIL [Intersil Corporation], HC55120CM Datasheet - Page 25

• Manufacturer Part Number: HC55120CM
• Description: Low Power Universal SLIC Family
• Manufacturer: INTERSIL [Intersil Corporation]

Battery Selection
Battery selection is a technique, for a two battery supply
system, where the SLIC automatically diverts the loop
current to the most appropriate supply for a given loop
length. This results in significant power savings and lowers
the total power consumption on short loops. This technique
is particularly useful if most of the lines are short, and the on
hook condition requires a -48V battery. In Figure 26, it can
be seen that for long loops the majority of the current comes
from the high battery supply (V
the low battery supply (V
Pinouts - 28 Lead PLCC Packages
HC55120, HC55121, HC55130, HC55131, HC55140, HC55141, HC55142, HC55143, HC55150, HC55151
RDC_RAC
RDC_RAC
BGND
BGND
RING
RING
VBH
VBH
VBL
CRT
CRT
VBL
TIP
TIP
10
11
10
11
5
6
7
8
9
5
6
7
8
9
12
12
4
4
(28 LEAD PLCC)
(28 LEAD PLCC)
13
13
3
3
BL
TOP VIEW
TOP VIEW
HC55120
HC55130
14
14
4-25
2
2
).
15
15
BH
1
1
) and for short loops from
28
16
28
16
27
17
27
17
26
18
26
18
25
24
23
22
21
20
19
25
24
23
22
21
20
19
AGND
RSYNC
ILIM
ROH
RD
V
GKD
AGND
RSYNC
ILIM
ROH
RD
V
NC
CC
CC
CRT_REV_
RDC_RAC
RDC_RAC
FIGURE 26. BATTERY SELECTION (DUAL SUPPLY SYSTEMS)
CRT_REV
BGND
RING
40
35
30
25
20
15
10
VBH
BGND
VBL
LVM
5
0
RING
TIP
VBH
VBL
TIP
10
11
V
5
6
7
8
9
10
11
BL
5
6
7
8
9
V
BH
12
4
12
4
13
3
13
3
(28 LEAD PLCC)
(28 LEAD PLCC)
LOOP RESISTANCE ( )
14
2
14
2
TOP VIEW
TOP VIEW
HC55121
HC55140
15
1
15
1
28
16
28
16
27
17
27
17
VBH = -48V
VBL = -24V
RILim = 33.2k
26
18
26
18
25
24
23
22
21
20
19
25
24
23
22
21
20
19
AGND
RSYNC_REV
ILIM
ROH
RD
V
GKD_LVM
AGND
RSYNC_REV
ILIM
ROH
RD
V
GKD
CC
CC
V
V
BH
BL