ISL59960 Datasheet, PDF (15/17 Pages) Intersil Corporation – 960MegaQ™: An Automatic 960H and Composite Video Equalizer, Fully-Adaptive to 4000 Feet

ISL59960
Bypassing and Layout
Considerations
960MegaQ™ 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 14 is an example of how to use vias to remove
heat from the IC.
FIGURE 14. 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_S
M
A
X
+
(
V_S
–
V_O
U
T
)
×
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
15
FN8358.0
December 18, 2012