AD9891KBCZ Analog Devices Inc, AD9891KBCZ Datasheet - Page 12

• Manufacturer Part Number: AD9891KBCZ
• Manufacturer: Analog Devices Inc

Specifications of AD9891KBCZ

• Analog Front End Type: CCD
• Analog Front End Category: Video
• Interface Type: Serial (3-Wire)
• Operating Supply Voltage (min): 2.7/3V
• Resolution: 10b
• Number Of Adc's: 1
• Power Supply Type: Analog/Digital
• Operating Temp Range: -20C to 85C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Pin Count: 64
• Package Type: CSPBGA
• Number Of Channels: 1
• Lead Free Status / RoHS Status: Compliant

AD9891/AD9895
PRECISION TIMING HIGH SPEED TIMING GENERATION
The AD9891/AD9895 generates flexible, high speed timing
signals using the Precision Timing core. This core is the founda-
tion for generating the timing used for both the CCD and the
AFE: the reset gate RG, horizontal drivers H1–H4, and the
SHP/SHD sample clocks. A unique architecture makes it rou-
tine for the system designer to optimize image quality by
providing precise control over the horizontal CCD readout and
the AFE correlated double sampling.
The high speed timing of the AD9891/AD9895 operates the
same in either Master or Slave Mode configuration.
Timing Resolution
The Precision Timing core uses a 1 master clock input (CLI) as
a reference. This clock should be the same as the CCD pixel
clock frequency. Figure 7 illustrates how the internal timing
core divides the master clock period into 48 steps or edge posi-
tions. Using a 20 MHz CLI frequency, the edge resolution of
the Precision Timing core is 1 ns. If a 1
available, it is also possible to use a 2 reference clock by pro-
gramming the CLIDIVIDE Register (Addr x01F). The AD9891/
AD9895 will then internally divide the CLI frequency by two.
POSITION
NOTES
PIXEL CLOCK PERIOD IS DIVIDED INTO 48 POSITIONS, PROVIDING FINE EDGE RESOLUTION FOR HIGH SPEED CLOCKS.
THERE IS A FIXED DELAY FROM THE CLI INPUT TO THE INTERNAL PIXEL PERIOD POSITIONS (
PERIOD
1 PIXEL
CLI
PROGRAMMABLE CLOCK POSITIONS:
1: RG RISING EDGE
2: RG FALLING EDGE
3: SHP SAMPLE LOCATION
4: SHD SAMPLE LOCATION
5: H1 RISING EDGE POSITION AND 6: H1 FALLING EDGE POSITION (H2 IS INVERSE OF H1)
7: H3 RISING EDGE POSITION AND 8: H3 FALLING EDGE POSITION (H4 IS INVERSE OF H3)
SIGNAL
t
CLIDLY
CCD
RG
H1
H2
H3
H4
1
5
Figure 7. High Speed Clock Resolution from CLI Master Clock Input
P[0]
7
2
Figure 8. High Speed Clock Programmable Locations
system clock is not
3
6
8
P[12]
4
–12–
P[24]
The AD9891/AD9895 also includes a master clock output,
CLO, which is the inverse of CLI. This output is intended to be
used as a crystal driver. A crystal can be placed between the
CLI and CLO Pins to generate the master clock for the
AD9891/AD9895. For more information on using a crystal, see
Figure 51.
High Speed Clock Programmability
Figure 8 shows how the high speed clocks RG, H1–H4, SHP,
and SHD are generated. The RG pulse has programmable
rising and falling edges, and may be inverted using the polarity
control. The horizontal clocks H1 and H3 have programmable
rising and falling edges and polarity control. The H2 and H4
clocks are always inverses of H1 and H3, respectively.
Table I summarizes the high speed timing registers and their
parameters. Figure 9 shows the typical 2-phase H-clock
arrangement in which H3 and H4 are programmed for the same
edge location as H1 and H2.
The edge location registers are six bits wide, but there are only
48 valid edge locations available. Therefore, the register values
are mapped into four quadrants, with each quadrant containing
12 edge locations. Table II shows the correct register values for
t
CLIDLY
P[36]
= 6ns TYP).
P[48] = P[0]
REV. A