
Preliminary Technical Data
ADA4938-1
ABSOLUTE MAXIMUM RATINGS
Rev. PrD | Page 7 of 14
Table 3.
Parameter
Supply Voltage
Power Dissipation
Storage Temperature Range
Operating Temperature Range
Lead Temperature (Soldering, 10 sec)
Junction Temperature
Stresses above those listed under Absolute Maximum
Rating 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 device (including exposed pad)
soldered to a high thermal conductivity 2s2p circuit board,
as described in EIA/JESD 51-7.
Rating
12 V
See Figure 2
65°C to +125°C
40°C to +85°C
300°C
150°C
Table 4. Thermal Resistance
Package Type
16-Lead LFCSP (Exposed Pad)
θ
JA
95
Unit
°C/W
Maximum Power Dissipation
The maximum safe power dissipation in the ADA4938-1
package 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 can change the stresses that the package exerts on the
die, permanently shifting the parametric performance of
the ADA4938-1. Exceeding a junction temperature of 150°C
for an extended period can result in changes in the silicon
devices, potentially causing failure.
The power dissipated in the package (P
D
) is the sum of the
quiescent power dissipation and the power dissipated in the
package due to the load drive. The quiescent power is the
voltage between the supply pins (V
S
) times the quiescent
current (I
S
). The power dissipated due to the load drive depends
upon the particular application. The power due to load drive is
calculated by multiplying the load current by the associated
voltage drop across the device. RMS voltages and currents must
be used in these calculations.
Airflow increases heat dissipation, effectively reducing θ
JA
. In
addition, more metal directly in contact with the package
leads/exposed pad from metal traces, through-holes, ground,
and power planes reduces the θ
JA
.
Figure 2 shows the maximum safe power dissipation in the
package vs. the ambient temperature for the 16-lead LFCSP
(95 °C/W) on a JEDEC standard 4-layer board.
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
–45
105
95
85
75
65
55
45
35
25
15
5
–5
AMBIENT TEMPERATURE (°C)
–15
–25
–35
M
0
Figure 2. Maximum Power Dissipation vs. Temperature for a 4-Layer Board
ESD CAUTION