EL5421 Intersil Corporation, EL5421 Datasheet - Page 10

• Manufacturer Part Number: EL5421
• Description: Buffer, Quad 12MHz, Rail-to-rail Input-Output, 4.5 to 16.5V, SR=10v/uS
• Manufacturer: Intersil Corporation

Short Circuit Current Limit
The EL5421 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.
Output Phase Reversal
The EL5421 is immune to phase reversal as long as the
input voltage is limited from V
shows a photo of the output 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.
Power Dissipation
With the high-output drive capability of the EL5421 buffer, it
is possible to exceed the 125°C 'absolute-maximum junction
temperature' under certain load 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 buffer to remain in the
safe operating area.
The maximum power dissipation allowed in a package is
determined according to:
where:
T
T
θ
P
FIGURE 2. OPERATION WITH BEYOND-THE-RAILS INPUT
AMAX
JA
JMAX
DMAX
= Thermal Resistance of the Package
= Maximum Ambient Temperature
= Maximum Junction Temperature
= Maximum Power Dissipation in the Package
1V
1V
P
DMAX
=
T
-------------------------------------------- -
JMAX
10
S
- -0.5V to V
Θ
–
JA
10µs
T
AMAX
V
T
V
S
S
A
IN
=±2.5V
=25°C
+ +0.5V. Figure 2
=6V
P-P
EL5421
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:
when sourcing, and:
when sinking.
Where:
If we set the two P
can solve for R
Figure 4 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 simple
matter to see if P
curves. To ensure proper operation, it is important to
observe the recommended derating curves shown in Figure
3 and Figure 4.
i = 1 to 4 for Quad
V
I
V
I
FIGURE 3. PACKAGE POWER DISSIPATION VS AMBIENT
SMAX
LOAD
P
S
OUT
P
DMAX
= Total Supply Voltage
DMAX
1200
1000
600
400
200
800
i = Maximum Output Voltage of the Application
i = Load current
0
= Maximum Supply Current Per Channel
0
MSOP10 Package Mounted on JEDEC JESD51-7 High
Effective Thermal Conductivity Test Board
=
870mW
=
Σi V
TEMPERATURE
Σi V
LOAD
[
[
DMAX
25
S
DMAX
S
×
i to avoid device overheat. Figure 3 and
×
I
SMAX
I
SMAX
Ambient Temperature (°C)
exceeds the device's power derating
50
equations equal to each other, we
+
+
(
V
(
V
OUT
75
S
+ V
85
i V
–
–
MAX T
100
OUT
S
- )
i )
×
J
=125°C
I
×
LOAD
125
I
LOAD
i
]
i
150
]