MAX9504AEUT+T Maxim Integrated Products, MAX9504AEUT+T Datasheet - Page 8

• Manufacturer Part Number: MAX9504AEUT+T
• Description: IC AMP VIDEO HI CUR SOT23-6
• Manufacturer: Maxim Integrated Products

Specifications of MAX9504AEUT+T

• Applications: General Purpose
• Number Of Circuits: 1
• -3db Bandwidth: 47MHz
• Slew Rate: 165 V/µs
• Current - Supply: 5mA
• Current - Output / Channel: 110mA
• Voltage - Supply, Single/dual (±): 2.7 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: SOT-23-6
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Video current DACs source current into a resistor con-
nected to ground. The output voltage range for com-
posite video and luma (Y) is usually from ground up to
1V (see Figure 1). Notice that the sync tip is quite close
to ground. Standard single-supply amplifiers with rail-
to-rail outputs have difficulty amplifying input signals at
or near ground because their output stages enter a
nonlinear mode of operation when the output is pulled
close to ground.
The MAX9504B level shifts the input signal up by
160mV so that the output has a positive DC offset of
3V/5V, 6dB Video Amplifiers with
High Output-Current Capability
Figure 1. Oscilloscope Trace of Luma and Chroma Signals
from Video Current DAC
Figure 2. 2nd-Order Butterworth LPF with MAX9504
8
_______________________________________________________________________________________
GND
GND
CURRENT
VIDEO
DAC
Using the MAX9504A/MAX9504B
Applications Information
with Video Current DACs
150Ω
10µs/div
R1
2-POLE RECONSTRUCTION LPF
150pF
C1
MAX9504 fig01
3.9µH
L1
LUMA
500mV/div
CHROMA
500mV/div
R2
150Ω
320mV. As a result, the MAX9504B output stage always
operates in the linear mode. Even if the input signal is
at ground, the MAX9504B output is at 320mV.
At the output of a video current DAC, the blank level of
the chroma signal is usually between 500mV to 650mV.
The voltage swing above and below the blank level is
approximately ±350mV (see Figure 1). If the blank level
is 550mV, then the lowest voltage for the chroma signal
is 200mV. For the case of chroma signals, no input
level shift is needed because 200mV gained up by two
is 400mV, which is well within the linear output range of
the MAX9504A or MAX9504B. Since the MAX9504A
does not have an input level shift, the MAX9504A
should be used with chroma signals. In summary, use
the MAX9504B with composite video and luma signals
from a DAC, and use the MAX9504A with chroma sig-
nals from a DAC.
In most video applications, the video signal generated
from the DAC requires a reconstruction filter to smooth
out the steps and reduce the spikes. The MAX9504 has
a high-impedance, DC-coupled input that can be con-
nected directly to the reconstruction filter.
For standard-definition video, the video passband is
approximately 6MHz, and the DAC sampling clock is
27MHz. Normally, a 9MHz lowpass filter can be used
for the reconstruction filter. This section demonstrates
the methods to build simple 2nd- and 3rd-order pas-
sive Butterworth lowpass filters with 9MHz cutoff fre-
quency. See Figures 2 and 3.
V
CC
Using the MAX9504A/MAX9504B with a
SHDN
IN
MAX9504
GND
V
CC
Video Reconstruction Filter
OUT
FB
C7
0.1µF
75Ω
R3
V
V
CC
OUT