LUCL8567AAU-D AGERE [Agere Systems], LUCL8567AAU-D Datasheet - Page 31

• Manufacturer Part Number: LUCL8567AAU-D
• Description: SLIC for Peoples Republic of China Applications
• Manufacturer: AGERE [Agere Systems]

Data Sheet
August 1999
Applications
Power Considerations
Inserting values into equation 4:
P
P
At this point, the idea is to choose a value of R
vary V
50 V to the very short loop (~100 ) value of 5 V in
both equations 9 and 10. For the choice of R
relationship in equation 9 must be met to ensure that
sufficient power is dissipated in R
L8567 SLIC is not driven into thermal shutdown.
At the same time, for the choice of R
will tell what the power rating of R
Obviously, it is desirable to minimize P
10 to minimize the cost associated with component
R
An easy way to vary V
to use a computer-based spreadsheet program.
Table 18 shows a spreadsheet for the choice of R
2600 . As shown, for this choice of resistor under
short loop conditions, the power dissipated in the SLIC
exceeds 1.33 W; thus, the SLIC may be driven into
thermal shutdown. Therefore, 2600
priate choice of R
In Table 19, R
this spreadsheet, under no loop conditions does the
SLIC power dissipation exceed 1.33 W. Thus, in terms
of SLIC power dissipation, 2200
choice. Looking at the power dissipated in resistor
R
says a rating of 2 W (with margin) is appropriate for
2200 .
In Table 20, R
Again, with this choice, the SLIC power does not
exceed 1.33 W, so in terms of SLIC power dissipation,
1800
1800 , the power dissipated in R
conditions exceeds 1 W, which suggests that for
1800 , the power rating of R
than 2 W. Thus, while 1800
be driven into thermal shutdown, because of the higher
power rating required compared to 2200 , 2200
better choice.
In Table 21, R
minimum value to get the power rating of R
0.5 W resistor. However, with this choice of resistor, the
Lucent Technologies Inc.
PWR
PWR
PWR
PWR
.
, the maximum power dissipation is 0.96 W, which
=
=
LOOP
is also an appropriate choice. However, with
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56
V
from the on-hook value of approximately
BAT
–
PWR
PWR
PWR
R
4
–
PWR
–
PWR
was reduced to 2200 . As shown in
was increased to 4400 . This is the
V
was further reduced to 1800 .
(continued)
V
R
ROH
LOO P
PWR
.
LOOP
–
V
2
for various values of R
LOO P
(continued)
PWR
ensures the SLIC will not
2
PWR
PWR
PWR
should be greater
is an appropriate
PWR
to ensure that
needs to be.
under short loop
is not an appro-
PRW
, equation 10
in equation
PWR
PWR
PWR
to a
, the
PWR
PWR
, and
(10)
is a
is
=
SLIC power will exceed 1.33 W; thus, 4400
appropriate. This result suggests that the minimum
power rating of R
1 W.
Table 22 and Table 23 show results for 2200
gest that a 5% tolerance is adequate for R
Table 18. R
Table 19. R
Table 20. R
5% and –5% variation, respectively. These tables sug-
P
P
P
1.334985
1.281138
1.208062
1.115754
1.004215
0.873446
0.723446
0.554215
0.365754
0.158062
1.180509
1.157782
1.112327
1.044145
0.953236
0.703236
0.544145
0.362327
0.157782
0.957378
0.974044
0.940711
0.790711
0.674044
0.357378
0.157378
People’s Republic of China Applications
SLIC
SLIC
0.8396
SLIC
0.9796
0.8796
0.5296
(W)
(W)
(W)
PWR
PWR
PWR
V
V
V
= 2600
= 2200
= 1800
LOOP
LOOP
LOOP
PWR
10
15
20
25
30
35
40
45
50
10
15
20
25
30
35
40
45
50
10
15
20
25
30
35
40
45
50
5
5
5
under the assumed conditions is
(V)
(V)
(V)
R
R
R
PWR
PWR
PWR
2600
2600
2600
2600
2600
2600
2600
2600
2600
2600
2200
2200
2200
2200
2200
2200
2200
2200
2200
2200
1800
1800
1800
1800
1800
1800
1800
1800
1800
1800
( )
( )
( )
L8567 SLIC for
PWR
P
P
P
0.849615
0.678462
0.526538
0.393846
0.280385
0.186154
0.111154
0.055385
0.018846
0.001538
1.004091
0.801818
0.622273
0.465455
0.331364
0.131364
0.065455
0.022273
0.001818
1.227222
0.760556
0.568889
0.268889
0.160556
0.027222
0.002222
PWR
PWR
PWR
0.405
0.22
0.98
0.08
.
is not
with a
(W)
(W)
(W)
31