MAX4138 MAXIM [Maxim Integrated Products], MAX4138 Datasheet - Page 10

• Manufacturer Part Number: MAX4138
• Description: 1-Input/6-Output Video Distribution Amplifiers
• Manufacturer: MAXIM [Maxim Integrated Products]

To drive larger-capacitance loads or to reduce ringing,
add an isolation resistor between the amplifier’s output
and the load, as shown in Figure 4.
The value of R
capacitive load. Figure 5 shows the optimal isolation
resistor (R
capacitor values, the bandwidth is dominated by the
RC network, formed by R
The MAX4135/MAX4136 can drive up to six outputs
simultaneously. Quiescent power dissipation is typically
750mW and 800mW maximum, respectively, with all
channels enabled. The maximum package power dissi-
pation is rated at 1540mW.
In a typical application, six outputs drive a standard
video signal into a 150Ω load. The amount of power
added to the quiescent dissipation is minimal and no
special precautions are necessary.
However, each output driving the maximum 65mA into
30Ω will cause a power-dissipation increase of approxi-
mately 200mW. Therefore, you should not allow more
than three outputs to deliver that load simultaneously.
Similarly, one output shorted to ground will cause a
power-dissipation increase of 650mW. Only one output
can be shorted to ground without violating the package
power rating.
1-Input/6-Output
Video Distribution Amplifiers
Figure 3. Effect of C
R
10
ISO
)
______________________________________________________________________________________
ISO
Power-Dissipation Considerations
14
12
10
8
6
4
2
0
) vs. capacitive load (C
ISO
0.1M
LOAD
depends on the circuit’s gain and the
1M
on Frequency Response (without
C
C
ISO
C
L
L
FREQUENCY (Hz)
L
= 15pF
= 10pF
= 5pF
and C
10M
L
.
100M
L
). At the higher
1G
In conclusion, during normal operation in a matched-
load environment, the total power dissipation is well
within the package’s dissipation rating. The maximum
power dissipation is violated only if multiple channels
are driving the maximum current into minimum loads at
the same time.
Figure 4. Capacitive-Load Driving Circuit
Figure 5. Optimal Isolation Resistor (R
V
IN
16
15
14
13
12
11
10
MAX4135
MAX4136
10
40
70
100
C
LOAD
R
130
(pF)
ISO
ISO
C
160
L
) vs. C
190
LOAD
220
R
L
V
OUT