EL4544IGZ Intersil, EL4544IGZ Datasheet - Page 24

• Manufacturer Part Number: EL4544IGZ
• Description: IC CROSSPOINT VID 16X5RGB 356BGA
• Manufacturer: Intersil

Specifications of EL4544IGZ

• Function: Crosspoint Switch
• Circuit: 3 x 16:5
• Voltage Supply Source: Single Supply
• Voltage - Supply, Single/dual (±): 4.75 V ~ 5.25 V, 2.4 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 356-PBGA
• Rohs Compliant: YES
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

connecting each to an external -5V supply. This keeps the
auto-zero circuitry active all the way down to ground.
Switchable Video Output Group Has Overlay
Capability and Offset Cancellation
The S group of output signals have an overlay switch that
allows single-ended inputs R
inserted on a pixel-by-pixel basis. The pin Ref
user to program the overlay input (reference) level that
produces an output voltage equal to the output reference pin
RefS. The S group of video outputs has an Auto-Calibration
mode which can null out offsets through the entire selected
signal path from its inputs to its outputs. (It is usually
triggered during the front or back porch of video when the
input signal is known to be at Black Level.)
Transparent vs Opaque Overlays
The overlay input for the S group is directly selected by the
Overlay control pin Ovl. Two types of overlay are possible.
The simplest overlay alternates between the dedicated
overlay input and the "thru" input (that has been selected by
the cross-point multiplexor). The "transparent" overlay mode
is different from the standard overlay mode in that it presents
the average of the overlay input and the "thru" input signal
during overlay. The transparent mode is selected either by
driving the Trans pin low or by programming bit D2 in
Register D of the Serial Interface to a logical "1".
Serial Interface Control of the Auto-Calibration
Feature
Programming bit D0 in Register D of the Serial Interface to a
logical "1" activates the "Auto-Calibration" Mode which
allows offsets from all inputs to the S group to be nulled-out
via a calibration sequence. The programming Bit D1 in
Register D of the Serial Interface is called Toggle. It allows
for two modes of auto-calibration. If Toggle is programmed to
a logical "0", Toggle mode is inactive. The auto-calibration
cycle must be executed separately for both input groups (the
overlay and the through signal groups).
What Happens During an Auto-Calibration Cycle
The auto-calibration (auto-zero) feature only applies to the S
group of outputs. An auto-calibration cycle works as follows
for either the overlay input or a selected "thru" input from the
cross-point: During any time when the input signal is known
to be at a "zero-level" ("zero-level" is a differential-zero input
signal for any of the 16-RGB differential inputs or when the
pin voltages to the overlay inputs R
equal to Ref
"LO" activates the sample phase of auto-calibration and
forces the analog outputs to be equal to the reference
voltage of pin RefS. When pin Cal is brought back to a
logical "HI", the calibration is held until the next calibration
cycle, and the S group will accurately convey the video
signal with low offsets. A small hold-step (≤1mV) can be
observed whenever the calibration signal is released. Each
subsequent activation of the sampling phase refreshes the
OL
), setting the calibration pin Cal to a logical
OL
24
, G
OL
OL
, and B
= G
OL
OL
= B
OL
, to be
OL
allows the
are all
EL4544
calibration. If Toggle mode is inactive, the user must
individually calibrate both the overlay and non-overlay
("thru") output states by selecting the between them and
running calibration separately for both of the input
conditions. Changing the input selections by reprogramming
the crosspoint to another input path or by changing the
overlay mode (transparent/opaque), requires refreshing of
this calibration. Ideally, the calibration is refreshed once per
line of video. The drift during a line of video is negligible. (On
the lab bench, using manual control, a drift rate on the order
of 0.2mV/s will be observed.)
Toggle Mode Automatically Supervises the
Calibration Cycles
The purpose of Toggle mode is to automatically alternate
between calibrating the overlay and calibrating the "thru"
paths to the S Output group. The Toggle mode assumes that
overlays never exist outside of the video screen (that overlay
only occurs during active video). When using the Toggle
mode, the overlay function must be inactive during and
around sync. When Toggle mode is active and the overlay
switch is disabled, the EL4544 will automatically toggle
between "thru" and overlay selections for alternate pulsing of
the calibrate signal. Thus, every alternate calibrate pulse will
override the selected "thru" state of the overlay switch,
perform an auto-zero function, and then return the overlay
switch back to its original "thru" position. This is true if the
programming Bit D1 in Register D (labelled Toggle) of the
Serial Interface is programmed to a logical "1". Whenever
the IC is reset by momentarily pulling the Reset pin "LO", the
Toggle mode is initialized such that the first path calibrated is
the overlay path. The next calibration cycle will automatically
calibrate the "thru" path.
Incorrect Use of the Toggle Mode
If the overlay is selected during auto-calibration with the
Toggle mode active, the "thru" path will never be calibrated.
Only the overlay gets calibrated in this configuration.
Integrated Die Temperature Probes
Thermal monitoring pins TMon1 and TMon2 allow the user
to effectively monitor the die temperature by lightly forward
biasing internal diodes and measuring their forward voltage
drop. Since these diodes will have a -2mV/°C tempco, they
can be an effective means of evaluating the thermal
management of the user's application board and may even
be configured to provide a thermally-triggered shutdown. To
implement this feature, pull either of these pins below the
negative supply with precision current source of 10µA to
100µA. Measure the forward drop at room temperature with
the chip disabled. During operation, every +1°C rise in
temperature will produce a 2mV drop in the forward voltage.
Some Tips on the Most Effective Programming of
the EL4544
The video inputs present a 1.75kΩ single ended and a 3.5kΩ
differential load to an incoming video signal. Since this load
December 21, 2007
FN7362.4