MAX7474EAE+T Maxim Integrated Products, MAX7474EAE+T Datasheet - Page 6

• Manufacturer Part Number: MAX7474EAE+T
• Description: IC ADAPTV EQ VID OVER UTP 16SSOP
• Manufacturer: Maxim Integrated Products
• Type: Equalizerr

Specifications of MAX7474EAE+T

• Applications: Security Systems
• Mounting Type: Surface Mount
• Package / Case: 16-SSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Adaptive Equalizer for
Video Over Twisted Pair
The MAX7474 compensates for cable losses that
occur when transmitting a composite video signal over
unshielded twisted-pair cable (see the Typical
Application Circuit ). The device automatically adapts
to cable length by monitoring the sync and color-burst
amplitudes of the color video signal at the output
(OUT) and adjusting the gains accordingly. Video sig-
nals without burst are automatically detected and a
user-selectable fixed equalization is applied to the sig-
nal. The MAX7474 provides full equalization up to
300m of Category 5e cable and greatly improves per-
formance up to 600m.
The MAX7474 accepts differential video input signals in
NTSC or PAL standards. The MAX7474 includes an
output unity-gain video driver and adjustable back-
porch DC level. The device also features LOS and LOB
logic outputs.
The MAX7474 accepts a differential video input with a
maximum 2.4V
carries the differential video signal to the positive (INP)
and negative (INN) inputs, which are AC-coupled with
0.022µF capacitors. Each input is internally clamped to
a DC level (see the Input Clamp section).
6
5, 10, 13
1, 2, 3,
_______________________________________________________________________________________
PIN
4, 9
11
12
14
15
16
6
7
8
P-P
NAME
BPLVL
FEQ0
FEQ1
GND
LOB
OUT
V
LOS
INN
INP
CC
voltage swing. A twisted-pair cable
Detailed Description
Ground. Connect all GND terminals together.
Power-Supply Input. Connect a +4.75V to +5.25V supply to V
Bypass each V
Loss-of-Burst Logic Output. LOB goes high when the output color burst goes below the LOB threshold
(V
when the output color burst exceeds V
device enters the fixed equalization mode. LOB is valid only when LOS is low.
Back-Porch Level Input. The voltage applied to BPLVL sets the output back-porch voltage level.
Composite Video Output
Fixed-Cable Equalization inputs. FEQ0 and FEQ1 set the fixed equalization level. See Table 1.
Noninverted Video Input. AC-couple video signal with a 0.022µF capacitor.
Inverted Video Input. AC-couple video signal with a 0.022µF capacitor.
Loss-of-Sync Logic Output. LOS goes high when the input sync amplitude goes below the loss-of-sync
threshold (V
exceeds V
impedance state.
LOB
) for 32 consecutive horizontal lines when the equalizer is at its maximum gain. LOB goes low
LOS
LOS
for 32 consecutive horizontal lines. When LOS is active, the output enters a high-
CC
) for 32 consecutive horizontal lines. LOS is pulled low when the input sync amplitude
Video Input
input with a 0.1µF capacitor to GND as close as possible to the device.
LOB
The MAX7474 clamps the sync tip of the input signal to
internally set DC levels effectively correcting, on a line-
by-line basis, any shift in the sync-tip level of the input
video signal. The sync-tip of the positive video input
signal (V
tive video input signal (V
3.2V. The input clamp enables capacitive coupling of
the input, permitting a large common-mode DC differ-
ence between the line driver (camera) and the device.
The adaptive equalizer in the MAX7474 provides the
appropriate inverse frequency response needed to
compensate for UTP cable loss. The equalizer adjusts
the low-frequency amplitude and chroma amplitude of
the input CVBS signal. The low-frequency component
of the CVBS is adjusted according to the feedback
information obtained from the internal automatic gain-
control (AGC) circuit, which monitors the sync pulse
amplitude of the output signal (see the Automatic Gain
Control (AGC) section). The chroma gain of the video
signal is adjusted according to the feedback informa-
tion obtained from the internal automatic equalization
control circuit, which monitors the color-burst amplitude
of the output signal (see the Automatic Equalization
Control (AEQ) section).
for 32 consecutive horizontal lines. When LOB is active, the
FUNCTION
INP
) is clamped to typically 2.0V and the nega-
CC
. Connect both V
INN
) is clamped to typically
Pin Description
Adaptive Equalizer
CC
inputs together.
Input Clamp