MAX7449EUD+ Maxim Integrated, MAX7449EUD+ Datasheet - Page 5

• Manufacturer Part Number: MAX7449EUD+
• Description: Active Filter Integrated Circuits (ICs)
• Manufacturer: Maxim Integrated

Specifications of MAX7449EUD+

• Number Of Channels: 3
• Cutoff Frequency: 5 MHz
• Supply Voltage - Max: 5.25 V
• Supply Voltage - Min: 4.75 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: TSSOP EP
• Minimum Operating Temperature: - 40 C
• Factory Pack Quantity: 96

The MAX7449 filters and buffers video-encoder DAC
outputs in applications such as set-top boxes, HDRs,
DVD players, and digital VCRs. The MAX7449 recon-
structs and cleans up component RGB analog video
signals. Each channel consists of a lowpass filter and
an output video buffer that drives two standard 150Ω
video loads.
This device operates from a single +5V supply and has
a nominal cutoff frequency of 5MHz optimized for
NTSC, PAL, and SDTV.
The reconstruction filter consists of two 2nd-order Sallen-
Key stages. The Butterworth-type response features a
maximally flat passband for NTSC and PAL bandwidths.
The stopband offers at least 43dB (typ) of attenuation at
a sampling frequency of ≥27MHz (see the Typical
Operating Characteristics).
Each output buffer has a fixed gain of +6dB and can
drive two 150Ω video loads with a 2V
MAX7449 can drive an AC load or drive the video load
directly without using a large output capacitor. The out-
put buffers drive DC loads with an output blanking level
of less than 1V.
When a sync pulse is detected on EXTSYNC, the DC
restore loop is activated for channels A, B, and C. The
function of the loop is to set the DC level of the video
signal to the desired level. See Table 1 for clamp levels.
Table 1. Output Clamp Level
CHANNEL
C
A
B
_______________________________________________________________________________________
Detailed Description
3-Channel Video Reconstruction Filter
Output Clamp Level
CLAMP LEVEL (V)
Output Buffers
Filter Response
P-P
1.5
1.5
1.5
signal. The
Filter
for RGB Component Video
Use 0.1µF ceramic capacitors to AC-couple the inputs.
These input capacitors store a DC level so the outputs
are clamped to an appropriate DC voltage level. The
MAX7449 allows R, G, or B video signals to be processed
by any channel. G must not have sync information.
The outputs are typically connected to a 75Ω series
back-match resistor followed by the video cable.
Because of the inherent divide-by-two of this configura-
tion, the voltage on the video cable is always less than
1V, complying with industry-standard video require-
ments such as the European SCART standard (which
allows up to 2V of DC on the video cable). The video
buffer can also drive an AC-coupled video load. Good
video performance is achieved with an output capacitor
as low as 220µF.
The MAX7449 operates from a single +5V supply.
Bypass V
external components as close to the device as possible.
The TSSOP-EP package has an exposed pad on the
bottom of the package. This pad is electrically connect-
ed to GND and should be connected to the ground
plane for improved thermal conductivity. Do not route
signals under this package.
TRANSISTOR COUNT: 6300
PROCESS: BiCMOS
TOP VIEW
Power-Supply Bypassing and Layout
CC
to GND with a 0.1µF capacitor. Place all
EXTSYNC
DISABLE
Applications Information
GND
V
INC
INA
INB
CC
1
2
3
4
5
6
7
Output Considerations
MAX7449
Pin Configuration
TSSOP
Chip Information
Input Considerations
Exposed Pads
14
13
12
11
10
9
8
N.C.
OUTA
OUTB
OUTC
V
N.C.
GND
CC
5