EL5120, EL5220, EL5420
output waveforms for the device in the unity-gain
configuration. Operation is from ±5V supply with a 10kΩ load
connected to GND. The input is a 10V sinusoid. The
current conditions. Therefore, it is important to calculate the
maximum junction temperature for the application to
determine if load conditions need to be modified for the
amplifier to remain in the safe operating area.
P-P
output voltage is approximately 9.985V
.
P-P
The maximum power dissipation allowed in a package is
determined according to:
V =±5V
S
T =25°C
A
A =1
V
T
– T
AMAX
Θ
V
=10V
IN
P-P
JMAX
P
= --------------------------------------------
DMAX
JA
where:
• T
• T
= Maximum junction temperature
= Maximum ambient temperature
JMAX
AMAX
• θ = Thermal resistance of the package
JA
• P
DMAX
= Maximum power dissipation in the package
FIGURE 25. OPERATION WITH RAIL-TO-RAIL INPUT AND
OUTPUT
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 loads, or:
Short Circuit Current Limit
The EL5120, EL5220, and EL5420 will limit the short circuit
current to ±120mA if the output is directly shorted to the
positive or the negative supply. If an output is shorted
indefinitely, the power dissipation could easily increase such
that the device may be damaged. Maximum reliability is
maintained if the output continuous current never exceeds
±30mA. This limit is set by the design of the internal metal
interconnects.
P
= Σi × [V × I
+ (V + – V
i) × I
i]
LOAD
DMAX
S
SMAX
S
OUT
when sourcing, and:
P
= Σi × [V × I
+ (V
i – V -) × I
i]
LOAD
DMAX
S
SMAX
OUT
S
when sinking.
where:
Output Phase Reversal
The EL5120, EL5220, and EL5420 are immune to phase
• i = 1 to 2 for dual and 1 to 4 for quad
• V = Total supply voltage
reversal as long as the input voltage is limited from (V -)
S
S
-0.5V to (V +) +0.5V. Figure 26 shows a photo of the output
S
of the device with the input voltage driven beyond the supply
rails. Although the device's output will not change phase, the
input's overvoltage should be avoided. If an input voltage
exceeds supply voltage by more than 0.6V, electrostatic
protection diodes placed in the input stage of the device
begin to conduct and overvoltage damage could occur.
• I
= Maximum supply current per amplifier
SMAX
• V
• I
i = Maximum output voltage of the application
i = Load current
OUT
LOAD
If we set the two P
can solve for R
equations equal to each other, we
DMAX
i to avoid device overheat. Figures 27
LOAD
and 28 provide a convenient way to see if the device will
overheat. The maximum safe power dissipation can be
found graphically, based on the package type and the
ambient temperature. By using the previous equation, it is a
1V
100µs
simple matter to see if P
exceeds the device's power
DMAX
derating curves. To ensure proper operation, it is important
to observe the recommended derating curves in Figures 27
and 28.
V =±2.5V
S
T =25°C
A
A =1
V
IN
V
=6V
P-P
1V
FIGURE 26. OPERATION WITH BEYOND-THE-RAILS INPUT
Power Dissipation
With the high-output drive capability of the EL5120, EL5220,
and EL5420 amplifiers, it is possible to exceed the 125°C
“absolute-maximum junction temperature” under certain load
FN7186.4
11
February 21, 2005