GS4901B Datasheet, PDF (1/95 Pages) Gennum Corporation – SD Clock and Timing Generator with GENLOCK

GS4901B/GS4900B
SD Clock and Timing Generator
with GENLOCK
GS4901B/GS4900B Preliminary Data Sheet
Key Features
Video Clock Synthesis
• Pre-programmed for 4 video clock periods (14.32 MHz,
27 MHz, 36 MHz, and 54 MHz)
• Accuracy of free-running clock frequency limited only by
crystal reference
• One differential and two single-ended video clock outputs
• Each clock may be individually delayed for skew control
• Video output clock may be directly connected to
Gennum’s serializers for a SMPTE-compliant SDI output
Audio Clock Synthesis (GS4901B only)
• Three audio clock outputs
• Generates any audio clock up to 512*96kHz
• Pre-programmed for 7 audio clocks
Timing Generation
• Generates up to 8 timing signals at a time
• Choose from 9 pre-programmed timing signals: H and V
sync and blanking, F Sync, F Digital, AFS (GS4901B
only), Display Enable, 10FID, and up to 4 user-defined
timing signals
• Pre-programmed to generate timing for 9 different video
formats
Genlock Capability
• Clocks may be free-running or genlocked to an input
reference with a variable offset step size of 100-200ps
(depending on exact clock frequency)
• Variable timing offset step size of 100-200ps up to one
frame
• Output may be cross-locked to a different input reference
• Freeze operation on loss of reference
• Optional crash or drift lock on application of reference
• Automatic input format detection
General Features
• Reduces design complexity and saves board space -
9mm x 9mm package plus crystal reference replaces
multiple VCXOs, PLLs and timing generators
• Pb-free and RoHS Compliant
• Low power operation typically 300mW
• 1.8V core and 1.8V or 3.3V I/O power supplies
• 64-PIN QFN package
Applications
• Video cameras; Digital audio and/or video recording/play
back devices; Digital audio and/or video processing
devices; Computer/video displays; DVD/MPEG devices;
Digital Set top boxes; Video projectors; High definition
video systems; Multi-media PC applications
Description
The GS4901B is a highly flexible, digitally controlled
clock synthesis circuit and timing generator with
genlock capability. It can be used to generate video and
audio clocks and timing signals, and allows multiple
devices to be genlocked to an input reference.
The GS4900B includes all the features of the GS4901B,
but does not offer audio clocks or AFS pulse generation.
The GS4901B/GS4900B will recognize input reference
signals conforming to 36 different video standards, and
will genlock the output timing information to the
incoming reference. The GS4901B/GS4900B supports
cross-locking, allowing the output to be genlocked to an
incoming reference that is different from the output
video standard selected.
The user may select to output one of 4 different video
sample clock rates. The chosen clock frequency can be
further divided using internal dividers, and is available
on two video clock outputs and one LVDS video clock
output pair. The video clocks are frequency and
phased-locked to the horizontal timing reference, and
can be individually delayed with respect to the timing
outputs for clock skew control.
Eight user-selectable timing outputs are provided that
can automatically produce the following timing signals
for 9 different video formats: HSync, Hblanking, VSync,
Vblanking, F sync, F digital, AFS (GS4901B only), DE,
and 10FID. These timing outputs may be locked to the
input reference signal for genlock timing and may be
phase adjusted via internal registers.
In addition, the GS4901B provides three audio sample
clock outputs that can produce audio clocks up to 512fs
with fs ranging from 9.7kHz to 96kHz. Audio to video
phasing is accomplished by an external 10FID input
reference, a 10FID signal specified via internal
registers, or a user-programmed audio frame
sequence.
The GS4901B/GS4900B is Pb-free, and the
encapsulation compound does not contain halogenated
flame retardant (RoHS Compliant).
37703 - 0 April 2006
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