DATASHEET
VIDEO GENLOCK PLL
Description
The MK9173-01/-15 provide the analog PLL circuit blocks
to implement a frequency multiplier. Because the device is
configured to use an external divider in the PLL clock
feedback path, a large divider can be used to result in a
large frequency multiplication ratio. This is useful when
using a low frequency input clock to generate a high
frequency output clock. The MK9173-01/-15 contains a
phase detector, charge pump, loop filter, and
voltage-controlled oscillator (VCO). The ICS674-01 can be
used as the external feedback divider.
A common application of the MK9173-01/-15 is the
implementation of a video genlock circuit. Because of this,
the MK9173-01/-15 inputs operate on the negative-going
clock edge.
The MK9173-01/-15 is pin and function compatible to the
AV9173-01/15.
MK9173-01/-15
Features
•
Phase-detector/VCO circuit block
•
Ideal for genlock system
•
Reference clock range 12 kHz to 1 MHz for full output
clock range
•
Output clock range of 1.25 to 75 MHz (-01), and 0.625 to
37.5 MHz (-15). See “Allowable Input Frequency to
Output Frequency” table for conditions
•
•
•
•
•
On-chip loop filter
Single 5 V power supply
Low power CMOS technology
8-pin SOIC package
For new video genlock applications, please refer to the
ICS673-01, ICS1522 or ICS1523.
Block Diagram
IDT™
VIDEO GENLOCK PLL
1
MK9173-01/-15
REV C 12/21/06
MK9173-01/-15
VIDEO GENLOCK PLL
CLOCK SYNTHESIZER
Using the MK9173-01/-15 in Genlock Applications
Most video sources, such as video cameras, are
asynchronous, free-running devices. To digitize video or
synchronize one video source to another free-running
reference video source, a video “genlock” (generator lock)
circuit is required. The MK9173-01/-15 integrate the analog
blocks which make the task much easier.
In the complete video genlock circuit, the primary function of
the MK9173-01/-15 is to provide the analog circuitry
required to generate the video dot clock within a PLL. This
application is illustrated in Figure 1. The input reference
signal for this circuit is the horizontal synchronization
(H-SYNC) signal. If a composite video reference source is
being used, the h-sync pulses must be separated from the
composite signal. A video sync separator circuit, such as the
National Semiconductor LM1881, can be used for this
purpose.
The clock feedback divider shown in Figure 1 is a digital
divider used within the PLL to multiply the reference
frequency. Its divide ratio establishes how many video dot
clock cycles occur per h-sync pulse. For example, if 880
pixel clocks are desired per h-sync pulse, then the divider
ratio is set to 880. Hence, together the h-sync frequency and
external divider ratio establish the dot clock frequency:
f
OUT
= f
IN
x N where N is external divide ratio
Both input pins IN and FBIN respond only to negative-going
clock edges of the input signal. The H-SYNC signal must be
constant frequency in the 12 kHz to 1 MHz range and stable
(low clock jitter) for creation of a stable output clock.
The output hook-ups of the MK9173-01/-15 are dictated by
the desired dot clock frequency. The primary consideration
is the internal VCO which operates over a frequency range
of 10 MHz to 75 MHz. Because of the selectable VCO
output divider and the additional divider on output CLK2,
four distinct output frequency ranges can be achieved. The
following Table lists these ranges and the corresponding
device configuration.
FS0
State
0
0
1
1
Output
Used
CLK1
CLK2
CLK1
CLK2
Frequency /Range
MK9173-01
10 to 75 MHz
5 to 37.5 MHz
2.5 to 18.75 MHz
1.25 to 9.375 MHz
Frequency /Range
MK9173-15
5 to 37.5 MHz
2.5 to 18.75 MHz
1.25 to 9.375 MHz
0.625 to 4.6875 MHz
Note that both outputs, CLK1 and CLK2, are available
during operation even though only one is fed back via the
external clock divider.
Pin 5, OE, tristates both CLK1 and CLK2 upon logic low
input. This feature can be used to revert dot clock control to
the system clock when not in genlock mode (hence, when in
genlock mode the system dot clock must be tristated).
When unused, inputs FS0 and OE must be tied to either
GND (logic low) or VDD (logic high).
Figure 1: Typical Application of MK9173-01/-15 in a Video Genlock System
IDT™
VIDEO GENLOCK PLL
3
MK9173-01/-15
REV C 12/21/06
MK9173-01/-15
VIDEO GENLOCK PLL
CLOCK SYNTHESIZER
Absolute Maximum Ratings
Stresses above the ratings listed below can cause permanent damage to the MK9173-01/-15. These ratings, which
are standard values for IDT commercially rated parts, are stress ratings only. Functional operation of the device at
these or any other conditions above those indicated in the operational sections of the specifications is not implied.
Exposure to absolute maximum rating conditions for extended periods can affect product reliability. Electrical
parameters are guaranteed only over the recommended operating temperature range.
Item
Supply Voltage, VDD
Storage Temperature
Voltage on I/O Pins referenced to GND
Junction Temperature
Soldering Temperature
Power Dissipation
7V
-65 to +150°C
Rating
GND - 0.5 V to VDD + 0.5 V
125°C
260°C
0.5 Watts
Recommended Operation Conditions
Parameter
Operating Temperature under Bias
Power Supply Voltage (measured with respect to
GND)
Min.
-0
+4.75
Typ.
+5 V
Max.
+70
+5.25
Units
°C
V
IDT™
VIDEO GENLOCK PLL
4
MK9173-01/-15
REV C 12/21/06
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