ISL59601_14 Datasheet, PDF (26/28 Pages) Intersil Corporation – MegaQ™: An Automatic Composite Video Equalizer,Fully-Adaptive to 1 Mile (1600m)

ISL59601, ISL59602, ISL59603, ISL59604, ISL59605
Bypassing and Layout
Considerations
MegaQ™ requires a dedicated ground plane in order to function
properly. For 2-layer boards, pour a quarter-inch ground plane
extending around the device on both the top and bottom layers.
Ensure that the ground plane on the bottom layer is a solid plane
with no traces cutting through it. Bypass capacitors must be
placed as close as possible to the device in order to ensure good
performance at longer lengths of equalization. Ensure that the
ground connections for the bypass capacitors connect directly to
the same uniform ground plane described previously.
General PowerPAD Design Considerations
The thermal pad must be connected to the ground plane for heat
dissipation. Figure 50 is an example of how to use vias to remove
heat from the IC.
FIGURE 50. PCB VIA PATTERN
The thermal pad is electrically connected to GND through the
high resistance IC substrate. We recommend you fill the thermal
pad area with vias. The via array should be centered in the
thermal pad and placed such that the center on center spacing is
3x the via radius. Vias should be small, but large enough to allow
solder wicking during reflow. Connect all vias to ground. It is
important the vias have a low thermal resistance for efficient
heat transfer. Do not use “thermal relief” patterns. It is important
to have a solid connection of the plated-through hole to each
plane.
Power Dissipation
The maximum power dissipation allowed in a package is
determined according to Equation 1:
PD_MAX = ^T----^J--^M-----^A---^X--_Θ---–-_J---_A^T---^A----^M----^A----^X-
(EQ. 1)
Where:
T_JMAX = Maximum junction temperature
T_AMAX = Maximum ambient temperature
Θ_JA = Thermal resistance of 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:
for sourcing use Equation 2:
PD_MAX
=
V_S
×
I_SMAX
+
(V_S
–
V_OUT)
×
-^V---^O----^U---^T-
R_L
(EQ. 2)
for sinking use Equation 3:
PD_MAX = V_S × I_SMAX + (V_OUT – V_S) × I_LOAD
(EQ. 3)
Where:
V_S = Supply voltage
I_SMAX = Maximum quiescent supply current
V_OUT = Maximum output voltage of the application
R_LOAD = Load resistance tied to ground
I_LOAD = Load current
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26
FN6739.2
September 5, 2012