EL2250C, EL2450C
125MHz Single Supply Dual/Quad Op Amps
conditions, or package type need to be modified for the
EL2250C/EL2450C to remain in the safe operating area.
The maximum power dissipation allowed in a package is
determined according to [1]:
T
– T
JMAX
AMAX
--------------------------------------------
PD
=
MAX
q
JA
where:
TJMAX = Maximum Junction Temperature
TAMAX = Maximum Ambient Temperature
qJA = Thermal Resistance of the Package
Figure 1.
PDMAX = Maximum Power Dissipation in the Package.
The maximum power dissipation actually produced by
an IC is the total quiescent supply current times the total
power supply voltage, plus the power in the IC due to the
load, or [2]
V
æ
ö
÷
ø
OUT
PD
= N ´
V
´ I
+ (V – V
) ´ ---------------
ç
MAX
s
SMAX
S
OUT
R
L
è
Figure 2.
Short Circuit Current Limit
The EL2250C/EL2450C have internal short circuit pro-
tection circuitry that protect it in the event of its output
being shorted to either supply rail. This limit is set to
around 100mA nominally and reduces with increasing
junction temperature. It is intended to handle temporary
shorts. If an output is shorted indefinitely, the power dis-
sipation could easily increase such that the part will be
destroyed. Maximum reliability is maintained if the out-
put current never exceeds ±90mA. A heat sink may be
required to keep the junction temperature below abso-
lute maximum when an output is shorted indefinitely.
where:
N = Number of amplifiers
VS = Total Supply Voltage
ISMAX = Maximum Supply Current per amplifier
VOUT = Maximum Output Voltage of the Application
RL = Load Resistance tied to Ground
If we set the two PDMAX equations, [1] & [2], equal to
each other, and solve for VS, we can get a family of
curves for various loads and output voltages according
to [3]:
Power Dissipation
With the high output drive capability of the
EL2250C/EL2450C, it is possible to exceed the 150°C
Absolute Maximum junction temperature under certain
load current conditions. Therefore, it is important to cal-
culate the maximum junction temperature for the
application to determine if power-supply voltages, load
R
´ (T
– T
)
AMAX
L
JMAX
---------------------------------------------------------------
+ (V
)
OUT
N ´ q
JA
------------------------------------------------------------------------------------------
=
V
S
(IS ´ R ) + V
L
OUT
12
ELANTEC [ ELANTEC SEMICONDUCTOR ]
