MAX11501 Datasheet, PDF (8/11 Pages) Maxim Integrated Products – Three-Channel, Standard-Definition Video Filters

Three-Channel,
Standard-Definition Video Filters
A sync tip exists at 280mV and peak white exists at
2.28V. The RMS voltage is approximately 1.88V on
each output (80% of the peak-to-peak voltage, plus the
offset) giving:
P_DS = 5 x 0.026 = 0.13W
(^{5 − 1.88}) ^{× 1.88}
P_DOn =
75
= 0.078W
and
P_D = 0.13 + 0.078 + 0.078 + 0.078 = 0.364W
The junction temperature is given by:
T_J = T_A + (R_θJA x P_D)
where T_J is junction temperature, T_A is ambient temper-
ature (assume +70°C), and R_θJA is thermal resistance
junction to ambient.
From the Absolute Maximum Ratings section of the data
sheet, the derating factor is 5.9mW/°C above +70°C.
R_θJA = 1/(derating factor) = 1/(5.9mW/°C) = 170°C/W
(derating and maximum power dissipation are based on
minimum PCB copper and indicate worst case).
Therefore:
T_J = 70 + (170 x 0.364) = +132°C
In this example, the die temperature is below the
absolute maximum allowed temperature. It is unlikely
under normal circumstances that the maximum die
temperature will be reached, however it is possible if
tolerances of V_CC, R_L, input voltage etc. are consid-
ered and the ambient temperature is high.
Changing the above example to a single video load on
each output results in:
T_J = +112°C
PCB Layout Recommendations
To help with heat dissipation, connect the power and
ground traces to large copper areas. Bypass V_CC to
GND with 0.1µF and 1.0µF capacitors. Surface-mount
capacitors are recommended for their low inductance.
Place traces carrying video signals appropriately to
avoid mutual coupling. When AC-coupling the inputs,
place the capacitors as close as possible to the device
and keep traces short to minimize parasitic capaci-
tance and inductance. For a recommended PCB lay-
out, refer to the MAX11501/MAX11502 evaluation kit
datasheet.
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