EL4501IU-T7 Intersil, EL4501IU-T7 Datasheet - Page 18
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EL4501IU-T7
Manufacturer Part Number
EL4501IU-T7
Description
IC VIDEO FRONT END AMP 24-QSOP
Manufacturer
Intersil
Datasheet
1.EL4501IUZ.pdf
(19 pages)
Specifications of EL4501IU-T7
Applications
Video Front End (VFE)
Number Of Circuits
1
-3db Bandwidth
100MHz
Slew Rate
96 V/µs
Current - Supply
10.5mA
Current - Output / Channel
70mA
Voltage - Supply, Single/dual (±)
4.5 V ~ 5.5 V
Mounting Type
Surface Mount
Package / Case
24-QSOP
Operating Supply Voltage (typ)
5V
Operating Supply Voltage (min)
4.5V
Operating Supply Voltage (max)
5.5V
Operating Temp Range
-40C to 85C
Operating Temperature Classification
Industrial
Package Type
QSOP
Mounting
Surface Mount
Pin Count
24
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Low jitter, temperature-stable timing signals are generated
using a master time-base, embedded within the system. Line
rate is adjustable from 10kHz to 135kHz using a single
external resistor (R
digital filter tracks line rate and rejects high frequency noise
and video artifacts, such as color burst. In addition to the
digital filter, a window-based, time qualification scheme is
employed to improve recovered signal quality. During loss of
signal, all outputs are blanked to prevent output chatter
caused by input noise.
The maximum total source impedance driving the SYNC IN
pin should be 1kΩ or lower. Source impedances greater than
1kΩ may reduce the ability of the EL4501 to reliably recover
the sync signal.
Composite Sync Output
The composite sync output is a reproduction of the signal
waveform below the composite video black level, with the
video completely removed. The composite video signal is
AC-coupled to SYNC IN (pin 9). The video signal passes
through a comparator whose threshold is controlled by the
SLICE MODE pin. The output of the comparator is buffered
to the COMPOSITE output (pin 11) as a CMOS logic signal.
Horizontal Sync Output
The horizontal circuit triggers on the falling edge of the sync
tip of the input composite video signal and produces a
horizontal output with pulse widths about 12 times the
internal oscillator clock. For NTSC video input, the pulse
width of the horizontal sync is 1.5µs, with the digital filter
selected. The half line pulses present in the input signal
during vertical blanking are removed with an internal
2H-eliminator circuit.
Vertical Sync Output
A low-going vertical sync pulse is generated during the start
of the vertical cycle of the incoming composite video signal.
The vertical output pulse is started on the first serration
pulse in the vertical interval and is ended on the second
rising edge during the vertical serration phase. In the
absence of vertical serration pulses, a vertical sync pulse will
be forced out after the vertical sync default delay time,
approximately 31µs after the last falling edge of the vertical
pre-equalizing pulse for R
Back Porch Output
In a composite video signal, the chroma burst is located on
the back porch of the horizontal blanking period and is also
the black level reference for the subsequent video scan line.
The back porch is triggered from the rising edge of the sync
tip. The pulse width of the back porch is about 29 times the
internal oscillator clock cycle. For the NTSC video input, the
pulse width of the back porch is about 3.5µs. In EL4501, the
back porch pulse controls the sample and hold switch of the
DC-restored loop.
FREQ
). An integrated, pin-selectable
FREQ
18
= 130kΩ.
EL4501
Odd and Even Output
For a composite video signal that is interlaced, there is an
odd field that includes all the odd lines, and an even field that
consists of the even lines. The odd and even circuit tracks
the relationship of the horizontal pulses to the leading edge
of the vertical output and will switch on every field at the start
of vertical sync pulse interval. ODD/EVEN, pin 14 is high
during the odd field and low during the even field.
Sync Amplitude Output
The output voltage at the SYNC AMP output (pin 17) is
about 2 times the sync tip voltage. This signal can be used
for AGC applications. When there is no sync signal at the
input, the SYNC AMP output is 0V.
Loss of Sync Output
Loss of video signal can be detected by monitoring the LOS
output at pin 10. LOS goes low indicating the EL4501 has
locked to the right line rate. LOS goes high indicating the
EL4501 is out of lock. When there is loss of sync, all the
sync outputs go high, except ODD/EVEN.
Digital Filter Operation
The EL4501 contains a user-selectable digital filter which
tracks the line rate and rejects high frequency noise and
video artifacts, such as color burst. Basically, the digital filter
delays all signals and filters out the pulses which are shorter
than the filters delay time. The digital filter greatly reduces
the jitters in the outputs. With the digital filter on, the jitter at
the composite sync output is only 2ns. Figure 39 shows the
jitter at the output when the digital filter is selected. However,
the output waveforms will be delayed from 150ns to 300ns
due to this filter. Refer to the performance curves for details.
Applying logic high to the FSEL pin, the digital filter is
enabled. Applying a logic low to the FSEL pin, the digital
filter is disabled.
R
An external R
produces a reference current that is used internally as the
timing reference for all the sync output delay time and output
pulse widths. Decreasing the value of R
reference current and frequency of the internal oscillator,
FREQ
FIGURE 39. JITTER AT THE OUTPUTS WITH FSEL=1
FREQ
CH2=2V/DIV
M=2ns
resistor, connected from pin 7 to ground,
FREQ
increases the