鈩?/div>
+ 200
鈩?
Loop off-hook power = 293.9 mW
SLIC off-hook power = Total off-hook power 鈥?loop
off-hook power
SLIC off-hook power = 744.4 mW 鈥?293.9 mW
SLIC off-hook power = 450.5 mW < 1.83 W
Thus, under the worst-case normal operating condi-
tions of this example, the thermal design, using the
auxiliary, is adequate to ensure the device is not driven
into thermal shutdown under worst-case operating con-
ditions.
Applications
Power Control
Under normal device operating conditions, power dissi-
pation on the device must be controlled to prevent the
device temperature from rising above the thermal shut-
down and causing the device to shut down. Power dis-
sipation is highest with higher battery voltages, higher
current limit, and under shorter dc loop conditions.
Additionally, higher ambient temperature will also
reduce thermal margin.
To support required power ringing voltages, this device
is meant to operate with a high-voltage primary battery
(鈥?5 V to 鈥?5 V typically). Thus, power control is nor-
mally achieved by use of the battery switch and an aux-
iliary lower absolute voltage battery. Operating
temperature range, maximum current limit, maximum
battery voltage, minimum dc loop length and protection
resistors values, airflow, and number of PC board lay-
ers will influence the overall thermal performance. The
following example illustrates typical thermal design
considerations.
The thermal resistance of the 28-pin PLCC package is
typically 35.5
擄C/W,
which is representative of the natu-
ral airflow as seen in a typical switch cabinet with a
multilayer board.
The L9500 will enter thermal shutdown at a typical tem-
perature of 150擄C. The thermal design should ensure
that the SLIC does not reach this temperature under
normal operating conditions.
For this example, assume a maximum ambient operat-
ing temperature of 85
擄C,
a designed current limit of
30 mA, a maximum battery of 鈥?5 V, and an auxiliary
battery of 鈥?1 V. Assume a (worst-case) minimum dc
loop of 20
鈩?/div>
of wire resistance, 30
鈩?/div>
protection resis-
tors, and 200
鈩?/div>
for the handset. Additionally, include
the effects of parameter tolerance.
1. T
TSD
鈥?T
AMBIENT(max)
= allowed thermal rise.
150擄C 鈥?85 擄C = 65 擄C.
2. Allowed thermal rise = package thermal
impedance
鈥?/div>
SLIC power dissipation.
65 擄C = 35.5擄C/W
鈥?/div>
SLIC power dissipation
SLIC power dissipation (P
D
) = 1.83 W.
Agere Systems Inc.
21
prev
next
LUCL9500AGF-D相關(guān)型號PDF文件下載
-
型號
版本
描述
廠商
下載
-
英文版
High-Voltage Ringing SLIC for VolP Applications
AGERE
-
英文版
High-Voltage Ringing SLIC for VolP Applications
AGERE [Age...
-
英文版
Telephone Ringer
ETC
-
英文版
Telephone Ringer
ETC
-
英文版
Telecom Switching Circuit
ETC
-
英文版
Telecom Switching Circuit
ETC
-
英文版
Telecom Switching Circuit
ETC
-
英文版
Telecom Switching Circuit
ETC
-
英文版
Telecom Switching Circuit
ETC
-
英文版
Telecom Switching Circuit
ETC
-
英文版
Subscriber Line Interface Circuit
ETC
-
英文版
Subscriber Line Interface Circuit
ETC
-
英文版
Dual-Resistive,Low-Cost Subscriber Line Interface Circuit(SL...
AGERE
-
英文版
Dual-Resistive,Low-Cost Subscriber Line Interface Circuit(SL...
AGERE [Age...
-
英文版
Telephone Ringer
ETC
-
英文版
Telephone Ringer
ETC
-
英文版
Telecom Switching Circuit
ETC
-
英文版
Telecom Switching Circuit
ETC
-
英文版
Telecom Switching Circuit
ETC
-
英文版
Telecom Switching Circuit
ETC