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MAX9510AUA+T

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P17
MAX9509/MAX9510
Short-Circuit Protection
The MAX9509/MAX9510
Functional Diagram/Typical
Application Circuit
includes a 75Ω back-termination
resistor that limits short-circuit current if an external short
is applied to the video output. The MAX9509/MAX9510
also feature internal output short-circuit protection to
prevent device damage in prototyping and applications
where the amplifier output can be directly shorted.
Shutdown
The MAX9509/MAX9510 feature a low-power shutdown
mode for battery-powered/portable applications.
Shutdown reduces the quiescent current to less than
10nA. Connecting SHDN to ground (GND) disables the
output and places the MAX9509/MAX9510 into a low-
power shutdown mode. In shutdown mode, the sync-tip
clamp, filter (MAX9509), amplifier, charge pump, and
linear regulator are turned off and the video output is
high impedance.
Applications Information
Power Consumption
The quiescent power consumption and average power
consumption of the MAX9509/MAX9510 are remarkably
low because of 1.8V operation and DirectDrive technolo-
gy. Quiescent power consumption is defined when the
MAX9509/MAX9510 are operating without load. In this
case, the MAX9509/MAX9510 consume approximately
5.8mW. Average power consumption, which is defined
when the MAX9509/MAX9510 drive a 150Ω load to
ground with a 50% flat field, is about 11.7mW. Table 1
shows the power consumption with different video sig-
nals. The supply voltage is 1.8V. OUT drives a 150Ω
load to ground.
Table 1. Power Consumption of MAX9509/
MAX9510 with Different Video Signals
Notice that the two extremes in power consumption occur
with a video signal that is all black and a video signal that
is all white. The power consumption with 75% color bars
and 50% flat field lies in between the extremes.
Interfacing to Video DACs that Produce
Video Signals Larger than 0.25V
P-P
Devices designed to generate 1V
P-P
video signals at
the output of the video DAC can still work with the
MAX9509/MAX9510. Most video DACs source current
into a ground-referenced resistor, which converts the
current into a voltage. Figure 3 shows a video DAC that
creates a video signal from 0 to 1V across a 150Ω
resistor. The following video filter amplifier has a gain of
2V/V so that the output is 2V
P-P
.
The MAX9509/MAX9510 expect input signals that are
0.25V
P-P
nominally. The same video DAC can be made
to work with the MAX9509/MAX9510 by scaling down the
150Ω resistor to a 37.5Ω resistor, as shown in Figure 4.
The 37.5Ω resistor is 1/4 the size of the 150Ω resistor,
resulting in a video signal that is 1/4 the amplitude.
1.8V, Ultra-Low Power, DirectDrive
Video Filter Amplifiers
10 ______________________________________________________________________________________
VIDEO SIGNAL
MAX9509 POWER
CONSUMPTION
(mW)
MAX9510 POWER
CONSUMPTION
(mW)
All Black Screen 6.7 6.2
All White Screen 18.2 17.9
75% Color Bars 11.6 11.0
50% Flat Field 11.7 11.3
150
Ω
0 TO 1V
LPF
DAC
IMAGE
PROCESSOR
ASIC
75
Ω
2V
P-P
2V/V
37.5
Ω
*FOR MAX9509 ONLY.
0 TO 0.25V
LPF*
DAC
IMAGE
PROCESSOR
ASIC
MAX9509
MAX9510
75
Ω
2V
P-P
8V/V
Figure 3. The video DAC generates a 1V
P-P
signal across a
150
Ω
resistor connected to ground.
Figure 4. The video DAC generates a 0.25V
P-P
signal across a
37.5
Ω
resistor connected to ground.
Anti-Alias Filter
The MAX9509 can also provide anti-alias filtering with a
buffer before an ADC, which would be present in a
NTSC/PAL video decoder, for example. Figure 5 shows
an example application circuit. An external composite
video signal is applied to VIDIN, which is terminated
with a total of 74Ω (56Ω and 18Ω resistors) to ground.
The signal is attenuated by four, and then AC-coupled
to IN. The normal 1V
P-P
video signal must be attenuat-
ed because with a 1.8V supply, the MAX9509 can only
handle a video signal of approximately 0.25V
P-P
at IN.
AC-couple the video signal to IN because the DC level
of an external video signal is usually not well specified,
although it is reasonable to expect that the signal is
between -2V and +2V. The 10Ω series resistor increas-
es the equivalent source resistance to approximately
25Ω, which is the minimum necessary for a video
source to drive the internal sync-tip clamp.
For external video signals larger than 1V
P-P
, operate
the MAX9509 from a 2.5V supply so that IN can accom-
modate a 0.325V
P-P
video signal, which is equivalent to
a 1.3V
P-P
video signal at VIDIN.
MAX9509/MAX9510
1.8V, Ultra-Low Power, DirectDrive
Video Filter Amplifiers
______________________________________________________________________________________ 11
MAX9509
SHUTDOWN
CIRCUIT
VIDEO
DECODER
LINEAR
REGULATOR
CHARGE PUMP
V
DD
DC-LEVEL
SHIFT
75Ω
75Ω
OUT
GND C1P
C1N
V
SS
C1
1µF
0.1µF
C2
1µF
V
DD
VIDIN
C3
0.1µF
IN
V
DD
= 1.8V
SHDN
CLAMP
LPF
10Ω
18Ω
56Ω
V
DD
A
V
= 8V/V
Figure 5. MAX9509 Used as an Anti-Alias Filter with Buffer
MAX9509/MAX9510
Video Source with a Positive DC Bias
In some applications, the video source generates a sig-
nal with a positive DC voltage bias, i.e., the sync tip of
the signal is well above ground. Figure 6 shows an
example in which the outputs of the luma (Y) DAC and
the chroma (C) DAC are connected together. Since the
DACs are current-mode, the output currents sum togeth-
er into the resistor, which converts the resulting current
into a voltage representing a composite video signal.
If the chroma DAC has an independent output resistor
to ground, then the chroma signal, which is a carrier at
3.58MHz for NTSC or at 4.43MHz for PAL, has a posi-
tive DC bias to keep the signal above ground at all
times. If the luma DAC has an independent output
resistor to ground, then the luma signal usually does
not have a positive DC bias, and the sync tip is at
approximately ground. When the chroma and luma sig-
nals are added together, the resulting composite video
signal still has a positive DC bias. Therefore, the signal
must be AC-coupled into the MAX9509/MAX9510
because the composite video signal is above the nomi-
nal, DC-coupled input range of 0 to 0.25V.
Video Signal Routing
Minimize the length of the PCB trace between the out-
put of the video DAC and the input of the MAX9509/
MAX9510 to reduce coupling of external noise into the
video signal. If possible, shield the PCB trace.
1.8V, Ultra-Low Power, DirectDrive
Video Filter Amplifiers
12 ______________________________________________________________________________________
Figure 6. Luma (Y) and chroma (C) signals are added together to create a composite video signal, which is AC-coupled into the
MAX9509/MAX9510.
MAX9509
MAX9510
SHUTDOWN
CIRCUIT
LINEAR
REGULATOR
CHARGE PUMP
V
DD
DC-LEVEL
SHIFT
OUT
GND C1P
C1N
V
SS
C1
1µF
C2
1µF
V
DD
DAC
VIDEO
ASIC
C3
0.1µF
IN
V
DD
= 1.8V
C
Y
SHDN
CLAMP
LPF*
*FOR MAX9509 ONLY.
DAC
75Ω
75Ω
A
V
= 8V/V
V
DD
0.1µF
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P17

MAX9510AUA+T

Mfr. #:
Buy MAX9510AUA+T
Manufacturer:
Maxim Integrated
Description:
Video Amplifiers 1.8V DirectDrive Video Filter Amp
Lifecycle:
New from this manufacturer.
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