MAX11501/MAX11502
Three-Channel,
Standard-Definition Video Filters
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Standard-Definition Filters
The MAX11501/MAX11502 filters are optimized to deliver
a flat (MAX11501) or high-frequency boosted (MAX11502)
passband and high stopband attenuation. The filter char-
acteristics have been chosen to provide excellent time
domain response with low overshoot. The typical -3dB fre-
quency of 8.6MHz (MAX11501) and 8.9MHz (MAX11502)
guarantee minimal attenuation in the passband while
at the same time offering a 27MHz attenuation of
typically -50dB (MAX11501) and -48dB (MAX11502).
Output Buffer
The MAX11501/MAX11502 feature output buffers with
+6dB of gain. A typical load (Figure 5(a)) is a 75Ω back-
match resistor, an optional 220µF or larger AC-coupling
capacitor, a transmission line, and a 75Ω termination
resistor. The MAX11501/MAX11502 clamp the signal,
forcing the blanking level to less than 1V at the termina-
tion resistor. This allows direct drive of video loads at
digital TV specifications without the need for costly AC-
coupling capacitors. The MAX11501/MAX11502 drive
two parallel loads per output (Figure 5(b)), but thermal
considerations must be taken into account when doing
so (see the
Junction-Temperature Calculations
section).
Applications Information
Output Configuration
The MAX11501/MAX11502 outputs may be either DC- or
AC-coupled. When the outputs are AC-coupled, choose
a capacitor that passes the lowest frequency content of
the video signal, and keeps the line-time distortion within
desired limits. The capacitor value is a function of the
input leakage and impedance of the circuit being driven.
The MAX11501/MAX11502 easily drive the industry com-
mon 220µF, or larger, coupling capacitor. If any or all
outputs are driving two parallel loads, see the
Junction-
Temperature Calculations
section.
The MAX11501/MAX11502 outputs are fully protected
against short circuits to ground. The short-circuit pro-
tection circuitry limits the output current to 80mA (typi-
cal) per output. Shorting more than one output to
ground simultaneously may exceed the maximum
package power dissipation.
Junction-Temperature Calculations
Die temperature is a function of quiescent power dissi-
pation and the power dissipation in the output drivers.
Calculate the power dissipated, P
D
, using:
P
D
= P
DS
+ P
DO1
+ P
DO2
+ P
DO3
where P
DS
is the quiescent power dissipated in the die,
and given by:
P
DS
= V
CC
x I
CC
and where P
DOn
is the power dissipated in the nth dri-
ver stage and given by:
where V
ORMSn
is the RMS output voltage and R
Ln
is the
load resistance.
The following is an example of a junction-temperature
calculation, assuming the following conditions:
1) Video standard = 525/60/2:1.
2) Video format = RGB with syncs on all.
3) Picture content = 100% white.
4) The input signal is AC-coupled.
5) The output signal is DC-coupled.
6) V
CC
= 5.0V.
7) I
CC
= 26mA.
