Datasheet

Data Sheet ADA4850-1/ADA4850-2
Rev. C | Page 5 of 16
ABSOLUTE MAXIMUM RATINGS
Table 3.
Parameter Rating
Supply Voltage 12.6 V
Power Dissipation See Figure 4
Power Down Pin Voltage (−V
S
+ 6) V
Common-Mode Input Voltage (−V
S
− 0.5 ) V to (+V
S
+ 0.5) V
Differential Input Voltage +V
S
to −V
S
Storage Temperature −65°C to +125°C
Operating Temperature Range −40°C to +125°C
Lead Temperature Range
(Soldering 10 sec)
300°C
Junction Temperature 150°C
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
THERMAL RESISTANCE
θ
JA
is specified for the worst-case conditions, that is, θ
JA
is
specified for the device soldered in the circuit board for
surface-mount packages.
Table 4.
Package Type θ
JA
Unit
16-Lead LFCSP
72.8
°C/W
8-Lead LFCSP 80 °C/W
Maximum Power Dissipation
The maximum safe power dissipation for the ADA4850-1/
ADA4850-2 is limited by the associated rise in junction
temperature (T
J
) on the die. At approximately 150°C, which
is the glass transition temperature, the plastic changes its
properties. Even temporarily exceeding this temperature limit
may change the stresses that the package exerts on the die,
permanently shifting the parametric performance of the
ADA4850-1/ADA4850-2. Exceeding a junction temperature
of 150°C for an extended period of time can result in changes
in silicon devices, potentially causing degradation or loss of
functionality.
The power dissipated in the package (P
D
) is the sum of the quies-
cent power dissipation and the power dissipated in the die due
to the ADA4850-1/ADA4850-2 drive at the output. The
quiescent power is the voltage between the supply pins (V
S
)
times the quiescent current (I
S
).
P
D
= Quiescent Power + (Total Drive Power − Load Power)
( )
L
OUT
L
OUTS
SS
D
R
V
R
V
V
IVP
2
2
−








×+×=
RMS output voltages should be considered. If R
L
is referenced
to −V
S
, as in single-supply operation, the total drive power is
V
S
× I
OUT
. If the rms signal levels are indeterminate, consider
the worst case, when V
OUT
= V
S
/4 for R
L
to midsupply.
( )
( )
L
S
SS
D
R
4V
IVP
2
/
+×=
In single-supply operation with R
L
referenced to −V
S
, the worst
case is V
OUT
= V
S
/2.
Airflow increases heat dissipation, effectively reducing θ
JA
.
Also, more metal directly in contact with the package leads and
exposed paddle from metal traces through holes, ground, and
power planes reduce θ
JA
.
Figure 4 shows the maximum safe power dissipation in the
package vs. the ambient temperature for the LFCSP (91°C/W)
package on a JEDEC standard 4-layer board. θ
JA
values are
approximations.
Figure 4. Maximum Power Dissipation vs. Temperature for a 4-Layer Board
ESD CAUTION
–55 125–45 –35 –25 –15 –5 5 15 25 35 45 55 65 75 85 95 105 115
MAXIMUM POWER DISSIPATION (W)
AMBIENT TEMPERATURE (°C)
05320-055
0
3.0
2.5
2.0
1.5
1.0
0.5
LFCSP-8
LFCSP-16
T
J
= 150°C