LUCL8567AAU-D AGERE [Agere Systems], LUCL8567AAU-D Datasheet - Page 29

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

Data Sheet
August 1999
Applications
Power Control—Auxiliary Battery
With the auxiliary battery technique under long loops,
the entire L8567 draws power from the higher-voltage
battery. As the loop length decreases and the loop
current increases or limits, the final output drive stage
of the L8567 SLIC will draw power from the lower-
voltage auxiliary battery. Thus, for a given loop, with a
given loop current requirement, the minimum battery
voltage is used by the L8567 SLIC, which minimizes
the total power consumed. During on-hook or open-
circuit conditions, the high battery is seen at tip and
ring.
All circuits on the L8567, other than the final output
drive stage, are powered by the higher-voltage battery
regardless of dc loop length. Thus, SLIC quiescent
power will be determined solely by the high-voltage
battery and will not be reduced under short dc loops.
Tip/ring voltage varies as a function of loop length,
decreasing with decreasing loop length. The battery
transition will occur when the tip/ring voltage is less
than V
Thus, the transition point from V
controlled by the choice of V
given below:
V
R
where:
V
T
R
I
conditions where it is likely that the SLIC will be current
limiting; thus, I
R
tance, nominal 68
R
V
I
R
(V
with battery switch circuit, typically 1 V.
Thus, the equation may be rewritten:
V
1 V
R
Thus, for example, for a nominal loop transition at
700 , with a 25 mA current limit, V
inal 27 V.
Lucent Technologies Inc.
LOOP
LIM
OH
BAT2
BAT2
BAT2
BAT2
LOOP
DC(TIP)
PROT
LOOP
DC(RING)
LOOP
DIODE +
= SLIC current limit set per resistor R
= overhead voltage tip to ground, typically 2.5 V.
.
= loop current. V
= T
= magnitude of auxiliary battery.
= 2.5 V + 55 I
= series protection resistance plus L758X resis-
BAT2
* I
= loop resistance for transition from V
=
= dc feed resistance on tip, typically 55 .
LIM
OH
V
V
--------------------------------
= dc feed resistance on ring, typically 55
CE(SAT)
BAT2
by a diode drop and a V
+ R
+ R
I
LIM
LOOP
–
DC(TIP)
DC(RING)
) = internal voltage drop associated
3.5
(continued)
LIM
= I
.
– 242
LIM
* I
BAT2
+ 132 I
* I
LOOP
.
LIM
will switch under short-loop
BAT2
+ (V
LIM
+ 2 * R
BAT1
. The relationship is
+ R
DIODE +
CE(SAT)
BAT2
LOOP
to V
PROT
should be nom-
V
BAT2
I
LIM
, or about 1 V.
* I
LIM
CE(SAT)
LOOP
.
BAT1
+ 55 I
may be
)
+
to
LIM
.
+
Power Control—32-Pin PLCC with Power
Control Resistor
This section is applicable if the user chooses to use a
single high-voltage battery with an external power con-
trol resistor. The power resistor is used in conjunction
with the 32-pin PLCC package.
Resistor R
tery supply. This resistor limits the power that is dissi-
pated on the SLIC. dc loop current is shared between
the SLIC and R
that is dissipated on the SLIC. The value and power rat-
ing of R
the L8567’s 32-pin PLCC package. The value and
power rating of R
The relationship for the power dissipated in the SLIC is
given by:
P
Where:
P
P
P
P
(and L758X switch).
P
P
The relationships for the individual power dissipation
components are:
P
P
the L8567 SLIC and is specified in Table 4 on page 12.
P
P
P
Where:
I
loop current limit that is set by resistor R
R
tance of the L758X switch.
|V
age.
V
lead.
V
tion of the dc loop length or resistance. It will decrease
with decreasing loop resistance.
R
LOOP
SLIC
SLIC
TOTAL
Q
PROT
PWR
LOOP
TOTAL
Q
PROT
PWR
LOOP
ROH
LOOP
P
PWR
BAT
People’s Republic of China Applications
is the value of the protection resistor plus the resis-
= the SLIC quiescent or on-hook power dissipation.
is the active state open loop power dissipation of
| is the magnitude of the maximum battery volt-
= P
= the power dissipated in the SLIC.
=
is the maximum dc loop current which is the dc
is the overhead voltage associated with the ring
= the power dissipated in R
is the resistance of the external resistor R
= the power dissipated in the protection resistors
= (I
= the power dissipated in the subscriber loop.
= V
is the ring/tip loop voltage. This voltage is a func-
= the total off-hook power dissipation.
= I
PWR
------------------------------------------------------------------------- -
TOTAL
V
LOOP
LOOP
LOOP
PWR
BAT
is determined by the thermal capabilities of
)
+ P
is connected from pin PWR to the bat-
2
–
PWR
|V
I
PWR
V
LOOP
R
Q
BAT
2R
ROH
, thus controlling the actual power
PWR
– P
|
P
is calculated as shown below.
PROT
–
V
LOO P
– P
PWR
2
PWR
– P
L8567 SLIC for
.
LOOP
PROG
.
PWR
.
(1)
(2)
(3)
(4)
(5)
29