ISL59601_14 Datasheet, PDF (22/28 Pages) Intersil Corporation – MegaQ™: An Automatic Composite Video Equalizer,Fully-Adaptive to 1 Mile (1600m)

ISL59601, ISL59602, ISL59603, ISL59604, ISL59605
CONTINUOUS UPDATE
In the Continuous Update mode, MegaQ™ will continuously try to
find the optimum equalization solution. When the equalization
has settled for 100 sequential video lines with no changes, the
LOCKED pin will go high. However once lock is achieved, noise
and average-picture-level changes may cause the device to
unlock, causing some image perturbation while MegaQ™
re-equalizes.
The Continuous Update mode is enabled whenever the FREEZE
pin is set to a logic low (grounded).
Polarity Detection and Correction
MegaQ™ features polarity detection and correction,
automatically detecting incorrectly-wired input signals and
inverting the signal inside the IC as necessary. The detected
polarity is indicated by the state of the INVERT pin.
The INVERT pin has 2 modes of operation. It is typically used to
indicate whether or not the incoming signal is inverted (the “+”
signal on the “-” input and vice-versa). The state of the invert
signal is then used to tell the signal processing logic whether or
not to invert the signal in the signal path.
A logic high on INVERT indicates that the positive differential
input signal is on IN- (pin 5) and the negative differential input
signal is on IN+ (pin 3). A logic low indicates nominal polarity.
However the unique design of the INVERT I/O pin (Figure 48) also
allows MegaQ™’s internal inversion detector to be overdriven
externally, forcing MegaQ™ to invert or not invert the signal
regardless of the state of the inversion detection function. This is
not necessary in normal operation, but it may improve
performance in particularly noisy environments when the polarity
of the signal is guaranteed to be correct.
INVERT
PIN
INVERSION
DETECTION
LOGIC
13k
ISL5960x
SIGNAL
PROCESSING
FIGURE 48. INVERT PIN STRUCTURE
The COLOR Pin
The color pin has 2 modes of operation. It is typically used to
indicate whether or not the incoming signal has a colorburst or
not. The state of the color signal is then used to tell the signal
processing logic whether or not it can rely on the presence of a
colorburst signal. A logic high indicates a color signal; a logic low
indicates monochrome.
COLOR
PIN
COLOR
DETECTION
LOGIC
13k
ISL5960x
SIGNAL
PROCESSING
FIGURE 49. COLOR PIN STRUCTURE
However the unique design of the COLOR I/O pin (Figure 49) also
allows MegaQ™’s internal color detector to be overdriven
externally. This is not necessary in normal operation, but it may
improve performance in particularly noisy environments when
the signal type is predetermined.
Monochrome Video Signals
MegaQ™ will equalize monochrome signals to the same distance
as color signals. However due to the high level of noise past
~4800 feet, the COLOR and LOCKED indicators may become
invalid for monochrome signals. The device will still equalize
properly if this occurs.
Security Cameras
MegaQ™ is ideal for security camera installations.
The automatic adaptive equalizer doesn't need any active silicon
on the transmit side of the cable, enabling upgrading of older
installations without having to touch the installed camera base,
including older monochrome cameras.
MegaQ™ automatically adjusts for wiring polarity errors as well
as adjusts for optimum image quality. These features eliminates
the need for the installer to make any adjustments.
With an extended equalization range of 5300ft, the ISL59605
enables cameras to be placed in even more remote locations,
enabling coverage of up to three square miles from a single
monitoring station.
Additional Equalization Modes Available
With the Serial Interface
In addition to the Lock Until Reset and Continuous Update
modes, software control of MegaQ™ through the SPI interface
adds a Lock Until Signal Loss mode and a Manual Equalization
mode.
Note: When controlling MegaQ™ through the SPI interface, the
external FREEZE pin must be tied to ground (logic low). Failure to
keep FREEZE at a logic low will prevent the software controls
from working properly.
All of the equalization modes are selected via the two “Locking
Mode/Manual Length Enable” register bits, 0x05[1:0].
CONTINUOUS UPDATE
Continuous Update mode is entered by setting address
0x05[1:0] = 00b. Continuous Update behavior is the same as
described in the stand-alone mode.
22
FN6739.2
September 5, 2012