LUCL9215AAU-D AGERE [Agere Systems], LUCL9215AAU-D Datasheet - Page 25

• Manufacturer Part Number: LUCL9215AAU-D
• Description: Short-Loop Sine Wave Ringing SLIC
• Manufacturer: AGERE [Agere Systems]

September 2001
Applications
dc Loop Current Limit
Note that the overall current-limit accuracy achieved
will not only be affected by the specified accuracy of
the internal SLIC current-limit circuit (accuracy associ-
ated with the 67 term), but also by the accuracy of the
voltage source and the accuracy of any external resis-
tor divider network used and voltage offsets due to the
specified input bias current. Tolerance of the current
limit is ±8%. If a resistor divider from V
recommended that the sum of the two resistors be
greater than 100 k .
The above equations describe the active mode steady-
state current-limit response. There will be a transient
response of the current-limit circuit upon an on- to off-
hook transition. Typical active mode transient current-
limit response is given in Table 19.
Table 19. Typical Active Mode On- to Off-Hook Tip/
Agere Systems Inc.
dc Loop Current:
dc Loop Current:
dc Loop Current:
Active Mode
R
Active Mode
R
Active Mode
R
LOOP
Transition t < 5 ms
LOOP
Transition t < 50 ms
LOOP
Transition t < 300 ms
= 100
= 100
= 100
Ring Current-Limit Transient Response
Parameter
On- to Off-hook
On- to Off-hook
On- to Off-hook
(continued)
(continued)
REF
I
I
LIM
LIM
Value
I
LIM
+ 60
+ 20
is used, it is
Unit
mA
mA
mA
Overhead Voltage
Active Mode
Overhead is programmable in the active mode via an
applied voltage source at the device’s OVH control
input. The voltage source may be an external voltage
source or derived via a resistor divider network from
the V
programmable external voltage source may be used to
provide software control of the overhead voltage. The
overhead voltage (V
by:
V
Overall accuracy is determined by the accuracy of the
voltage source and the accuracy of any external resis-
tor divider network used and voltage offsets due to the
specified input bias current. If a resistor divider from
V
more accurate result due to a lower offset associated
with the input bias current; however, lower value resis-
tors will also draw more power from V
Note that a default overhead voltage of 6.0 V is
achieved by shorting input pin OVH to analog ground.
The default overhead provides sufficient headroom for
an on-hook transmission of a 3.14 dBm signal into
900
Overhead voltage may need to be increased to accom-
modate on-hook transmission of higher-voltage sig-
nals, such as meter pulse. The following example is
meant to illustrate the design procedure that can be fol-
lowed.
Assume we need on-hook transmission of a 1.0 Vrms
meter pulse into 200
tion resistors are used.
V
V
V
OH
REF
OH
OH
OH
= 6.0 V + 5 * V
= 6.0 V + (1+ [2 * Rp]/200) * Vpeak
= 6.0 + (1+ [2 * 50]/200) * 1 (1.414)
= 8.121 V
REF
is used, a lower magnitude resistor will give a
.
Short-Loop Sine Wave Ringing SLIC
SLIC output or an external voltage source. A
OVH
OH
(V)
) is related to the OVH voltage
. Further, assume 50
REF
.
protec-
25