MAX9503GEEE+T Maxim Integrated Products, MAX9503GEEE+T Datasheet - Page 9

• Manufacturer Part Number: MAX9503GEEE+T
• Description: IC VIDEO AMP W/FILTER 16-QSOP
• Manufacturer: Maxim Integrated Products
• Series: DirectDrive™r

Specifications of MAX9503GEEE+T

• Applications: Filter
• Number Of Circuits: 1
• Current - Supply: 12mA
• Current - Output / Channel: 50mA
• Voltage - Supply, Single/dual (±): 2.7 V ~ 3.6 V
• Mounting Type: Surface Mount
• Package / Case: 16-SSOP (0.150", 3.90mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: MAX9503GEEE+TTR

Figure 1. AC-Coupled Output
The MAX9503 has an integrated charge pump and linear
regulator to create a low-noise negative supply from the
positive supply voltage. The charge pump inverts the
positive supply to create a raw negative voltage that is
then fed into the linear regulator, which outputs -2V. The
linear regulator filters out the charge-pump noise.
The actual level of the video signal varies less with a
DirectDrive output than an AC-coupled output. The
video signal average can change greatly depending
upon the picture content. With an AC-coupled output,
the average will change according to the time constant
formed by the series capacitor and series resistance
(usually 150Ω). For example, Figure 1 shows an AC-
coupled video signal alternating between a completely
black screen and a completely white screen. Notice the
excursion of the video signal as the screen changes.
With the DirectDrive amplifier, the black level is held at
ground. The video signal is constrained between
-0.3V to +0.7V. Figure 2 shows the video signal from a
DirectDrive amplifier with the same input signal as the
AC-coupled system.
Comparison Between DirectDrive Output
_______________________________________________________________________________________
2ms/div
vs. AC-Coupled Output
DirectDrive Video Amplifier with
INPUT
500mV/div
OUTPUT
500mV/div
Before the video signal from the DAC can be amplified,
it must be lowpass filtered to smooth the steps and to
reduce the spikes created whenever the DAC output
changes value. In the frequency domain, the steps and
spikes cause images of the video signal to appear at
multiples of the sampling clock. The MAX9503 contains
a six-pole Butterworth lowpass filter. The passband
extends to 5.5MHz, and the minimum attenuation is
35dB at 27MHz.
The MAX9503 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
MAX9503 features internal output, short-circuit protection
to prevent device damage in prototyping and applica-
tions where the amplifier output can be directly shorted.
The MAX9503 features a low-power shutdown mode for
battery-powered/portable applications. Shutdown
reduces the quiescent current to less than 10nA.
Connecting SHDN to ground (SGND) disables the out-
puts and places the MAX9503 into a low-power shut-
down mode. In shutdown mode, the amplifier, charge
pump, and linear regulator are turned off and the video
output impedance is 4kΩ.
Figure 2. DirectDrive Output
Reconstruction Filter
0V
0V
Video Reconstruction Filter
2ms/div
Short-Circuit Protection
INPUT
500mV/div
OUTPUT
1V/div
Shutdown
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