EL5221 Intersil Corporation, EL5221 Datasheet - Page 10

• Manufacturer Part Number: EL5221
• Description: Buffer, Dual 12MHz, Rail-to-rail Input-output
• Manufacturer: Intersil Corporation

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 EL5221 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:
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.
T
T
Θ
P
P
FIGURE 2. OPERATION WITH BEYOND-THE-RAILS INPUT
P
AMAX
JMAX
DMAX
DMAX
JA
DMAX
= Thermal resistance of the Package
= Maximum junction temperature
= Maximum ambient temperature
= Maximum power dissipation in the package
=
=
Σi V
Σi V
[
1V
1V
[
S
P
S
×
DMAX
×
I
I
SMAX
SMAX
=
+
+
T
-------------------------------------------- -
(
10
JMAX
(
V
V
OUT
S
10µS
+
Θ
- V
- T
i - V
JA
OUT
V
T
V
AMAX
S
A
IN
S
=±2.5V
=25°C
=6V
- )
i )
×
P-P
×
I
LOAD
I
LOAD
i
]
i ]
EL5221
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 2 for dual buffer
V
I
V
I
FIGURE 3. PACKAGE POWER DISSIPATION VS AMBIENT
FIGURE 4. PACKAGE POWER DISSIPATION VS AMBIENT
SMAX
LOAD
S
OUT
= Total supply voltage
i = Maximum output voltage of the application
i = Load current
= Maximum supply current per channel
0.8
0.6
0.4
0.2
0.6
0.5
0.4
0.3
0.2
0.1
1
0
0
0
TEMPERATURE
TEMPERATURE
Package Mounted on a JEDEC JESD51-7 High
Effective Thermal Conductivity Test Board
0
Package Mounted on a JEDEC JESD51-3 Low
Effective Thermal Conductivity Test Board
LOAD
870mW
435mW
486mW
391mW
DMAX
DMAX
25
25
i to avoid device overheat. Figure 3 and
Ambient Temperature (°C)
Ambient Temperature (°C)
exceeds the device's power derating
equations equal to each other, we
50
50
75 85
75 85
MAX T
MAX T
100
100
J
J
=125°C
=125°C
125
125
150
150