FEATURES
AD9891: 10-Bit 20 MHz Version
AD9895: 12-Bit 30 MHz Version
Correlated Double Sampler (CDS)
4 6 dB Pixel Gain Amplifier (
2 dB to 36 dB 10-Bit Variable Gain Amplifier (VGA)
10-Bit 20 MHz A/D Converter (AD9891)
12-Bit 30 MHz A/D Converter (AD9895)
Black Level Clamp with Variable Level Control
Complete On-Chip Timing Generator
Precision Timing
Core with 1 ns Resolution
On-Chip 5 V Horizontal and RG Drivers
2-Phase and 4-Phase H-Clock Modes
4-Phase Vertical Transfer Clocks
Electronic and Mechanical Shutter Modes
On-Chip Driver for External Crystal
On-Chip Sync Generator with External Sync Option
64-Lead CSPBGA Package
APPLICATIONS
Digital Still Cameras
Digital Video Camcorders
Industrial Imaging
PxGA
®
)
Precision Timing
™
Generator
AD9891/AD9895
PRODUCT DESCRIPTION
The AD9891 and AD9895 are highly integrated CCD signal
processors for digital still camera applications. Both include a
complete analog front end with A/D conversion combined with
a full-function programmable timing generator. A PrecisionTiming core allows adjustment of high speed clocks with 1 ns
resolution at 20 MHz operation and 700 ps resolution at 30
MHz operation.
The AD9891 is specified at pixel rates of up to 20 MHz, and
the AD9895 is specified at 30 MHz. The analog front end
includes black level clamping, CDS, PxGA, VGA, and a 10-Bit
or 12-Bit A/D converter. The timing generator provides all the
necessary CCD clocks: RG, H-clocks, V-clocks, sensor gate
pulses, substrate clock, and substrate bias control. Operation is
programmed using a 3-wire serial interface.
Packaged in a space-saving 64-lead CSPBGA, the AD9891 and
AD9895 are
–20°C to +85°C.
specified over an operating temperature range of
FUNCTIONAL BLOCK DIAGRAM
VRT VRB
4dB 6dB
CCDIN
RG
H1–H4
V1–V4
VSG1–VSG8
PxGA is a registered trademark and Precision Timing is a trademark of Analog Devices, Inc.
4
4
8
PxGACDS
CLAMP
HORIZONTAL
DRIVERS
V- H
CONTROL
VSUB SUBCKHD VD SYNC
2dB TO 36dB
VGA
INTERNAL CLOCKS
PRECISION
TIMING
GENERATOR
SYNC
GENERATOR
VREF
AD9891/AD9895
ADC
CLAMP
REGISTERS
CLI
SL SCK DATA
10 OR 12
DOUT
DCLK
CLPOB/PBLK
FD/LD
MSHUT
STROBE
CLO
INTERNAL
REV. A
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties that
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices.
POWER DISSIPATION–AD9891 (See TPC 1 for Power Curves)
20 MHz, Typ Supply Levels, 100 pF H1–H4 Loading380mW
Power from HVDD Only
Power-Down 1 Mode42mW
Power-Down 2 Mode8mW
Power-Down 3 Mode2.5mW
POWER DISSIPATION–AD9895 (See TPC 4 for Power Curves)
30 MHz, Typ Supply Levels, 100 pF H1–H4 Loading600mW
Power from HVDD Only
Power-Down 1 Mode138mW
Power-Down 2 Mode22mW
Power-Down 3 Mode2.5mW
MAXIMUM CLOCK RATE (CLI)
AD989120MHz
AD989530MHz
*
The total power dissipated by the HVDD supply may be approximated using the equation:
Total HVDD Power = [C
Reducing the H-loading, using only two of the outputs, and/or using a lower HVDD supply will reduce the power dissipation.
Actual HVDD power may be slightly higher than the calculated value because of stray capacitance inherent in the PCB layout/routing.
Specifications subject to change without notice.
*
*
HVDD Pixel Frequency]
LOAD
HVDD
Number of H-Outputs Used
220mW
320mW
DIGITAL SPECIFICATIONS
(RGVDD = HVDD = 4.75 V to 5.25 V, DVDD = DRVDD = 2.7 V to 3.5 V, CL = 20 pF, T
unless otherwise noted.)
MIN
to T
MAX
ParameterSymbolMinTypMaxUnit
LOGIC INPUTS
High Level Input VoltageV
Low Level Input VoltageV
High Level Input CurrentI
Low Level Input CurrentI
Input CapacitanceC
IH
IL
IH
IL
IN
2.1V
0.6V
10µA
10µA
10pF
LOGIC OUTPUTS (Except H and RG)
High Level Output Voltage @ IOH = 2 mAV
Low Level Output Voltage @ IOL = 2 mAV
OH
OL
2.2V
0.5V
RG and H-DRIVER OUTPUTS (H1–H4)
High Level Output Voltage @ Max CurrentV
Low Level Output Voltage @ Max CurrentV
OH
OL
VDD – 0.5V
0.5V
Maximum Output Current (Programmable)24mA
Maximum Load Capacitance (for Each Output)100pF
Specifications subject to change without notice.
,
REV. A–3–
AD9891/AD9895
AD9891–ANALOG SPECIFICATIONS
(AVDD1, AVDD2 = 3.0 V, f
= 20 MHz, T
CLI
MIN
to T
, unless otherwise noted.)
MAX
ParameterMinTypMaxUnitNotes
CDS
Gain0dB
Allowable CCD Reset Transient500mVInput signal characteristics*
Max Input Range before Saturation1.0V p-p
Max CCD Black Pixel Amplitude± 200mV
PIXEL GAIN AMPLIFIER (PxGA)
Max Input Range1.0V p-p
Max Output Range1.6V p-p
Gain Control Resolution64Steps
Gain MonotonicityGuaranteed
Gain Range
Min Gain (PxGA Code 32)–2.5dB
Med Gain (PxGA Code 0)+3.5dBDefault setting
Max Gain (PxGA Code 31)+9.5dB
VARIABLE GAIN AMPLIFIER (VGA)
Max Input Range1.6V p-p
Max Output Range2.0V p-p
Gain Control Resolution1024Steps
Gain MonotonicityGuaranteed
Gain Range
Low Gain (VGA Code 70)2dB
Max Gain (VGA Code 1023)36dB
BLACK LEVEL CLAMP
Clamp Level Resolution256Steps
Clamp LevelMeasured at ADC output
Reference Top Voltage (VRT)2.0V
Reference Bottom Voltage (VRB)1.0V
SYSTEM PERFORMANCEIncludes entire signal chain
Gain AccuracyIncludes 4 dB default PxGA gain
Low Gain (VGA Code 70)567dBGain = (0.035 Code) + 3.55 dB
Max Gain (VGA Code 1023)38.539.540.5dB
Peak Nonlinearity, 500 mV Input Signal0.2%12 dB gain applied
Total Output Noise0.6LSB rmsAC grounded input, 6 dB gain applied
Power Supply Rejection (PSR)40dBMeasured with step change on supply
*
Input signal characteristics defined as follows:
500mV TYP
RESET
TRANSIENT
200mV MAX
OPTICAL
BLACK PIXEL
Specifications subject to change without notice.
1V MAX
INPUT
SIGNAL RANGE
REV. A–4–
AD9891/AD9895
AD9895–ANALOG SPECIFICATIONS
(AVDD1, AVDD2 = 3.0 V, f
= 30 MHz, T
CLI
MIN
to T
, unless otherwise noted.)
MAX
ParameterMinTypMaxUnitNotes
CDS
Gain0dB
Allowable CCD Reset Transient500mVInput signal characteristics*
Max Input Range before Saturation1.0V p-p
Max CCD Black Pixel Amplitude± 200mV
PIXEL GAIN AMPLIFIER (PxGA)
Max Input Range1.0V p-p
Max Output Range1.6V p-p
Gain Control Resolution64Steps
Gain MonotonicityGuaranteed
Gain Range
Min Gain (PxGA Code 32)–2.5dB
Med Gain (PxGA Code 0)+3.5dBDefault setting
Max Gain (PxGA Code 31)+9.5dB
VARIABLE GAIN AMPLIFIER (VGA)
Max Input Range1.6V p-p
Max Output Range2.0V p-p
Gain Control Resolution1024Steps
Gain MonotonicityGuaranteed
Gain Range
Low Gain (VGA Code 70)2dB
Max Gain (VGA Code 1023)36dB
BLACK LEVEL CLAMP
Clamp Level Resolution256Steps
Clamp LevelMeasured at ADC output
Reference Top Voltage (VRT)2.0V
Reference Bottom Voltage (VRB)1.0V
SYSTEM PERFORMANCEIncludes entire signal chain
Gain AccuracyIncludes 4 dB default PxGA gain
Low Gain (VGA Code 70)567dBGain = (0.035 Code) + 3.55 dB
Max Gain (VGA Code 1023)38.539.540.5dB
Peak Nonlinearity, 500 mV Input Signal0.2%12 dB gain applied
Total Output Noise0.8LSB rmsAC grounded input, 6 dB gain applied
Power Supply Rejection (PSR)40dBMeasured with step change on supply
33.3ns
CLI High/Low Pulsewidth, AD98951316.7ns
Delay from CLI Rising Edge to Internal Pixel Position 0t
1
AFE CLAMP PULSES
CLPDM Pulsewidth410Pixels
CLPOB Pulsewidth
AFE SAMPLE LOCATION
(Figure 13)
2
1
(Figure 10)
SHP Sample Edge to SHD Sample Edge, AD9891t
SHP Sample Edge to SHD Sample Edge, AD9895t
DATA OUTPUTS (Figure 12)
Output Delay from DCLK Rising Edge
1
CLIDLY
S1
S1
t
OD
220Pixels
2025ns
1316.7ns
6ns
8ns
Pipeline Delay from SHP/SHD Sampling9Cycles
SERIAL INTERFACE (Figures 52 and 53)
Maximum SCK Frequencyf
SL to SCK Setup Timet
SCK to SL Hold Timet
SDATA Valid to SCK Rising Edge Setupt
SCK Falling Edge to SDATA Valid Holdt
SCK Falling Edge to SDATA Valid Readt
NOTES
1
Parameter is programmable.
2
Minimum CLPOB pulsewidth is for functional operation only. Wider typical pulses are recommended to achieve good clamp performance.
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection. Although the
AD9891 and AD9895 feature proprietary ESD protection circuitry, permanent damage may occur on
devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are
recommended to avoid performance degradation or loss of functionality.
REV. A–6–
AD9891 PIN CONFIGURATION
A1 CORNER
INDEX AREA
1234567 9108
A
B
C
AD9891
TOP
VIEW
(Not to Scale)
D
E
F
G
H
J
K
AD9891/AD9895
PIN FUNCTION DESCRIPTIONS
PinMnemonic Type2Description
A1VDDOVertical Sync Pulse
(Input for Slave Mode,
Output for Master Mode)
B1HDDOHorizontal Sync Pulse
(Input for Slave Mode,
Output for Master Mode)
C1SYNCDIExternal System Sync Input
C2LD/FDDOLine or Field Designator
Output
D1DCLKDOData Clock Output
D2CLPOB/DOCLPOB or PBLK Output
Crystal
C10CLIDIReference Clock Input
B10TCVDDPAnalog Supply for Timing Core
C9TCVSSPAnalog Ground for Timing
Core
A10AVDD1PAnalog Supply for AFE
B9AVSS1PAnalog Ground for AFE
A9BYP1AOAnalog Circuit Bypass
B8BYP2AOAnalog Circuit Bypass
A8CCDINAICCD Signal Input
A7BYP3AOAnalog Circuit Bypass
B7AVDD2PAnalog Supply for AFE
B6AVSS2PAnalog Ground for AFE
A6REFBAOVoltage Reference Bottom
Bypass
A5REFTAOVoltage Reference Top Bypass
B5SLDI3-Wire Serial Load Pulse
A4SDIDI3-Wire Serial Data Input
B4SCKDI3-Wire Serial Clock
A3MSHUTDOMechanical Shutter Pulse
B3STROBEDOStrobe Pulse
B2DVSSPDigital Ground
A2DVDDPDigital Supply for VSG,
V1–V4, HD, VD, MSHUT,
STROBE, and Serial Interface
NOTES
1
See Figure 50 for circuit configuration.
2
AI = Analog Input, AO = Analog Output, DI = Digital Input,
DO = Digital Output, DIO = Digital Input/Output, P = Power.
3
In Register Readback Mode
4
In Frame Transfer CCD Mode
REV. A
–7–
AD9891/AD9895
AD9895 PIN CONFIGURATION
A1 CORNER
INDEX AREA
1234567 9108
A
B
C
AD9895
TOP
VIEW
(Not to Scale)
D
E
F
G
H
J
K
PIN FUNCTION DESCRIPTIONS
PinMnemonic Type2Description
A1VDDOVertical Sync Pulse
(Input for Slave Mode,
Output for Master Mode)
B1HDDOHorizontal Sync Pulse
(Input for Slave Mode,
Output for Master Mode)
C1SYNCDIExternal System Sync Input
C2LD/FDDOLine or Field Designator
Output
D1DCLKDOData Clock Output
D2CLPOB/DOCLPOB or PBLK Output
Crystal
C10CLIDIReference Clock Input
B10TCVDDPAnalog Supply for Timing Core
C9TCVSSPAnalog Ground for Timing
Core
A10AVDD1PAnalog Supply for AFE
B9AVSS1PAnalog Ground for AFE
A9BYP1AOAnalog Circuit Bypass
B8BYP2AOAnalog Circuit Bypass
A8CCDINAICCD Signal Input
A7BYP3AOAnalog Circuit Bypass
B7AVDD2PAnalog Supply for AFE
B6AVSS2PAnalog Ground for AFE
A6REFBAOVoltage Reference Bottom
Bypass
A5REFTAOVoltage Reference Top Bypass
B5SLDI3-Wire Serial Load Pulse
A4SDIDI3-Wire Serial Data Input
B4SCKDI3-Wire Serial Clock
A3MSHUTDOMechanical Shutter Pulse
B3STROBEDOStrobe Pulse
B2DVSSPDigital Ground
A2DVDDPDigital Supply for VSG,
V1–V4, HD, VD, MSHUT,
STROBE, and Serial Interface
NOTES
1
See Figure 50 for circuit configuration.
2
AI = Analog Input, AO = Analog Output, DI = Digital Input,
DO = Digital Output, DIO = Digital Input/Output, P = Power.
An ideal ADC exhibits code transitions that are exactly 1 LSB
apart. DNL is the deviation from this ideal value. Thus, every
code must have a finite width. No missing codes guaranteed to
12-bit resolution indicates that all 4096 codes, respectively,
must be present over all operating conditions.
Peak Nonlinearity
Peak nonlinearity, a full signal chain specification, refers to the
peak deviation of the output of the AD9891/AD9895 from a
true straight line. The point used as “zero scale” occurs 0.5 LSB
before the first code transition. “Positive full scale” is defined as
a level 1 and 0.5 LSB beyond the last code transition. The
deviation is measured from the middle of each particular output
code to the true straight line. The error is then expressed as a
EQUIVALENT CIRCUITS
AV DD1
R
percentage of the 2 V ADC full-scale signal. The input signal is
always appropriately gained up to fill the ADC’s full-scale range.
Total Output Noise
The rms output noise is measured using histogram techniques. The
standard deviation of the ADC output codes is calculated in LSB
and represents the rms noise level of the total signal chain at the
specified gain setting. The output noise can be converted to an
equivalent voltage, using the relationship 1 LSB = (ADC Full
n
Scale/2
codes) when n is the bit resolution of the ADC. For the
AD9891, 1 LSB is 2 mV, while for the AD9895, 1 LSB is 0.5 mV.
Power Supply Rejection (PSR)
The PSR is measured with a step change applied to the supply
pins. The PSR specification is calculated from the change in the
data outputs for a given step change in the supply voltage.
DVD D
330
DATA
THREE-
STATE
AVSS1AVSS1
Figure 1. CCDIN
DVD D
DVSS
Figure 2. Digital Data Outputs
DRVDD
DRVSS
DOUT
RG, H1–H4
ENABLE
DVSS
Figure 3. Digital Inputs
HVDD OR
RGVDD
HVSS OR
RGVSS
Figure 4. H1–H4, RG Drivers
OUTPUT
REV. A
–9–
AD9891/AD9895–Typical Performance Characteristics
440
RGVDD = HVDD = 5.0V
400
360
320
280
POWER DISSIPATION – mW
240
200
10
VDD = 2.7V
VDD = 3.3V
VDD = 3.0V
15
SAMPLE RATE – MHz
TPC 1. AD9891 Power vs. Sample Rate
1.0
0.5
0
725
RGVDD = HVDD = 5.0V
650
VDD = 3.3V
575
VDD = 3.0V
500
425
POWER DISSIPATION – mW
350
20
275
10
20
SAMPLE RATE – MHz
VDD = 2.7V
30
TPC 4. AD9895 Power vs. Sample Rate
1.0
0.5
0
–0.5
–1.0
0
200600800
400
TPC 2. AD9891 Typical DNL Performance
4
3
2
OUTPUT NOISE – LSB
1
0
0
200
400
VGA GAIN CODE – LSB
600
800
TPC 3. AD9891 Output Noise vs. VGA Gain
1000
1000
–0.5
–1.0
0
80024003200
1600
TPC 5. AD9895 Typical DNL Performance
24
21
18
15
12
9
OUTPUT NOISE – LSB
6
3
0
0
200
400
VGA GAIN CODE – LSB
600
800
TPC 6. AD9895 Output Noise vs. VGA Gain
4000
1000
REV. A–10–
AD9891/AD9895
SYSTEM OVERVIEW
Figure 5 shows the typical system block diagram for the AD9891/
AD9895 used in Master Mode. The CCD output is processed by
the AD9891/AD9895’s AFE circuitry, which consists of a CDS,
PxGA, VGA, black level clamp, and an A/D converter. The digitized pixel information is sent to the digital image processor chip,
which performs the post-processing and compression. To operate
the CCD, all CCD timing parameters are programmed into the
AD9891/AD9895 from the system microprocessor, through the
3-wire serial interface. From the system master clock, CLI, provided by the image processor or external crystal, the AD9891/
AD9895 generates all of the CCD’s horizontal and vertical clocks
and all internal AFE clocks. External synchronization is provided
by a SYNC pulse from the microprocessor, which will reset
internal counters and resync the VD and HD outputs.
V- DRIVER
H1–H4, RG, VSUB
CCDIN
CCD
MSHUT
STROBE
V1–V4, VSG1–VSG8, SUBCK
AD989x
SERIAL
INTERFACE
P
SYNC
DOUT
DCLK
CLPOB/PBLK
LD/FD
HD, VD
CLI
DIGITAL
IMAGE
PROCESSING
ASIC
Figure 5. Typical System Block Diagram, Master Mode
Alternatively, the AD9891/AD9895 may be operated in Slave
Mode, in which the VD and HD are provided externally from
the image processor. In this mode, all AD9891/AD9895 timing
will be synchronized with VD and HD.
The H-drivers for H1–H4 and RG are included in the AD9891/
AD9895, allowing these clocks to be directly connected to the CCD.
H-drive voltage of up to 5 V is supported. An external V-driver is
required for the vertical transfer clocks, the sensor gate pulses,
and the substrate clock.
The AD9891/AD9895 also includes programmable MSHUT
and STROBE outputs, which may be used to trigger mechanical shutter and strobe (flash) circuitry.
Figure 6 shows the horizontal and vertical counter dimensions
for the AD9891/AD9895. All internal horizontal and vertical
clocking is programmed using these dimensions to specify line
and pixel locations.
MAXIMUM
FIELD
DIMENSIONS
12-BIT HORIZONTAL = 4096 PIXELS MAX
12-BIT VERTICAL = 4096 LINES MAX
Figure 6. Vertical and Horizontal Counters
REV. A
–11–
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 foundation 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 routine 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 positions. Using a 20 MHz CLI frequency, the edge resolution of
the Precision Timing core is 1 ns. If a 1 system clock is not
available, it is also possible to use a 2 reference clock by programming the CLIDIVIDE Register (Addr x01F). The AD9891/
AD9895 will then internally divide the CLI frequency by two.
POSITION
CLI
P[0]P[48] = P[0]P[12]P[24]P[36]
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
1 PIXEL
PERIOD
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 (
t
CLIDLY
= 6ns TYP).
Figure 7. High Speed Clock Resolution from CLI Master Clock Input
3
CCD
SIGNAL
12
RG
56
H1
H2
78
H3
H4
4
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)
Figure 8. High Speed Clock Programmable Locations
REV. A–12–
AD9891/AD9895
the corresponding edge locations. Figure 10 shows the range
and default locations of the high speed clock signals.
H-Driver and RG Outputs
In addition to the programmable timing positions, the AD9891/
AD9895 features on-chip output drivers for the RG and H1–H4
outputs. These drivers are powerful enough to directly drive the
CCD inputs. The H-driver current can be adjusted for optimum
rise/fall time into a particular load by using the DRV Registers
(Addr x0E1 to x0E4). The RG drive current is adjustable using
the RGDRV Register (Addr x0E8). Each 3-bit DRV Register is
adjustable in 3.5 mA increments, with the minimum setting of 0
equal to OFF or three-state, and the maximum setting of 7
equal to 24.5 mA.
As shown in Figure 11, the H2 and H4 outputs are inverses of
H1 and H3, respectively. The internal propagation delay resulting
from the signal inversion is less than 1 ns, which is significantly
less than the typical rise time driving the CCD load. This results
Table I. H1–H4, RG, SHP, and SHD Timing Parameters
in an H1/H2 crossover voltage at approximately 50% of the output swing. The crossover voltage is not programmable.
Digital Data Outputs
The AD9891/AD9895 data output and DCLK phase are programmable using the DOUTPHASE Register (Addr x01D). Any
edge from 0 to 47 may be programmed, as shown in Figure 12.
Normally, the DOUT and DCLK signals will track in phase,
based on the DOUTPHASE Register contents. The DCLK
output phase can also be held fixed with respect to the data
outputs, by changing the DCLKMODE Register (Addr x01E)
HIGH. In this mode, the DCLK output will remain at a fixed
phase equal to CLO (the inverse of CLI) while the data output
phase is still programmable.
There is a fixed output delay from the DCLK rising edge to the
DOUT transition, called t
. This delay can be programmed to
OD
four values between 0 ns and 12 ns, using the DOUT_DELAY
Register (Addr x032). The default value is 8 ns.
RegisterLengthRangeDescription
POL1bHigh/LowPolarity Control for H1, H3, and RG (0 = No Inversion, 1 = Inversion)
POSLOC6b0–47 Edge LocationPositive Edge Location for H1, H3, and RG
Sample Location for SHP, SHD
NEGLOC6b0–47 Edge LocationNegative Edge Location for H1, H3, and RG
DRV3b0–7 Current StepsDrive Current for H1–H4 and RG Outputs (3.5 mA per Step)
CCD
SIGNAL
RG
H1/H3
H2/H4
USING THE SAME TOGGLE POSITIONS FOR H1 AND H3 GENERATES STANDARD 2-PHASE H-CLOCKING.
Figure 9. 2-Phase H-Clock Operation
Table II. Precision Timing Edge Locations
QuadrantEdge Location (Dec)Register Value (Dec)Register Value (Bin)
I0 to 110 to 11000000 to 001011
II12 to 2316 to 27010000 to 011011
III24 to 3532 to 43100000 to 101011
IV36 to 4748 to 59110000 to 111011
REV. A
–13–
AD9891/AD9895
POSITION
PIXEL
PERIOD
RG
H1/H3
CCD
SIGNAL
NOTES
ALL SIGNAL EDGES ARE FULLY PROGRAMMABLE TO ANY OF THE 48 POSITIONS WITHIN ONE PIXEL PERIOD.
DEFAULT POSITIONS FOR EACH SIGNAL ARE SHOWN.
P[0]
RGr[0]
Hr[0]
RGf[12]
P[24]P[12]P[36]
Hf[24]
SHP[28]
t
S1
Figure 10. High Speed Clock Default and Programmable Locations
t
H1/H3
H2/H4
RISE
P[48] = P[0]
SHD[48]
t
<
t
PD
RISE
H1/H3
FIXED CROSSOVER VOLTAGE
t
PD
Figure 11. H-Clock Inverse Phase Relationship
P[0]P[48] = P[0]
PIXEL
PERIOD
DCLK
t
OD
DOUT
NOTES
DATA OUTPUT (DOUT) AND DCLK PHASE ARE ADJUSTABLE WITH RESPECT TO THE PIXEL PERIOD.
WITHIN 1 CLOCK PERIOD, THE DATA TRANSITION CAN BE PROGRAMMED TO 48 DIFFERENT LOCATIONS.
OUTPUT DELAY (
t
) FROM DCLK RISING EDGE TO DOUT RISING EDGE IS PROGRAMMABLE.
OD
P[12]P[24]P[36]
Figure 12. Digital Output Phase Adjustment
H2/H4
REV. A–14–
AD9891/AD9895
HORIZONTAL CLAMPING AND BLANKING
The AD9891/AD9895’s horizontal clamping and blanking pulses
are fully programmable to suit a variety of applications. As with
the vertical timing generation, individual sequences are defined
for each signal, which are then organized into multiple regions
during image readout. This allows the dark pixel clamping and
blanking patterns to be changed at each stage of the readout in
order to accommodate different image transfer timing and high
speed line shifts.
Individual CLPOB, CLPDM, and PBLK Sequences
The AFE horizontal timing consists of CLPOB, CLPDM, and
PBLK, as shown in Figure 13. These three signals are independently programmed using the registers in Table III. SPOL is
the start polarity for the signal, and TOG1 and TOG2 are the
first and second toggle positions of the pulse. All three signals
are active low and should be programmed accordingly. Up to
four individual sequences can be created for each signal.
HD
123
CLPOB
CLPDM
PBLK
PROGRAMMABLE SETTINGS:
1: START POLARITY (CLAMP AND BLANK REGION ARE ACTIVE LOW)
2: 1ST TOGGLE POSITION
3: 2ND TOGGLE POSITION
CLAMPCLAMP
Figure 13. Clamp and Preblank Pulse Placement
To simplify the programming requirements, the CLPDM signal
will track the CLPOB signal by default. If separate control of
the CLPDM signal is desired, the SINGLE_CLAMP Register
(Addr x031) should be set LOW.
Individual HBLK Sequences
The HBLK programmable timing shown in Figure 14 is similar
to CLPOB, CLPDM, and PBLK. However, there is no start
polarity control. Only the toggle positions are used to designate
the start and the stop positions of the blanking period. Additionally, there is a polarity control, HBLKMASK, that designates the
polarity of the horizontal clock signals H1–H4 during the blanking period. Setting HBLKMASK high will set H1 = H3 = Low
and H2 = H4 = High during the blanking, as shown in Figure 15.
Up to four individual sequences are available for HBLK.
Horizontal Sequence Control
The AD9891/AD9895 use sequence change positions (SCP)
and
sequence pointers (SPTR) to organize the individual hori-
HD
12
HBLK
PROGRAMMABLE SETTINGS:
1: 1ST TOGGLE POSITION = START OF BLANKING
2: 2ND TOGGLE POSITION = END OF BLANKING
THE POLARITY OF H1 DURING BLANKING IS PROGRAMMABLE (H2 IS OPPOSITE POLARITY OF H1)
REV. A
Figure 15. HBLK Masking Control
–15–
AD9891/AD9895
zontal
sequences. Up to four SCPs are available to divide the
readout into four separate regions, as shown in Figure 16. The
SCP0 is always hard-coded to line 0, and SCP1–SCP3 are
register programmable. During each region bound by the SCP,
the
SPTR Registers designate which sequence is used by each
signal.
CLPOB and CLPDM share the same SCP, PBLK has a
separate
set of SCP, and HBLK shares the vertical RCP (see
Vertical Timing Generation section). For example,
CLPSCP1 will define Region 0 for CLPOB and CLPDM,
and in that region
CLPDM sequences may be selected with the
The next SCP defines a new
any of the four individual
CLPOB and
region, and in that region each
SPTR Registers.
signal can be assigned to a different individual sequence. Because HBLK shares the vertical RCP, there are up to eight
regions where HBLK sequences may be changed using the eight
HBLKSPTR Registers.
Table III. CLPOB, CLPDM, and PBLK Individual Sequence Parameters
RegisterLengthRangeDescription
SPOL1bHigh/LowStarting Polarity of Vertical Transfer Pulse for Sequences 0–3
TOG112b0–4095 Pixel LocationFirst Toggle Position within Line for Sequences 0–3
TOG212b0–4095 Pixel LocationSecond Toggle Position within Line for Sequences 0–3
Table IV. HBLK Individual Sequence Parameters
RegisterLengthRangeDescription
HBLKMASK1bHigh/LowMasking Polarity for H1 for Sequences 0–3 (0 = H1 Low, 1 = H1 High)
HBLKTOG112b0–4095 Pixel LocationFirst Toggle Position within Line for Sequences 0–3
HBLKTOG212b0–4095 Pixel LocationSecond Toggle Position within Line for Sequences 0–3
Table V. Horizontal Sequence Control Parameters for CLPOB, CLPDM, and PBLK
RegisterLengthRangeDescription
SCP1–SCP312b0–4095 Line NumberCLPOB/PBLK SCP to Define Horizontal Regions 0–3
SPTR0–SPTR3 2b0–3 Sequence NumberSequence Pointer for Horizontal Regions 0–3
Table VI. Horizontal Sequence Control Parameters for HBLK
RegisterLengthRangeDescription
VTPRCP1–12b0–4095 Line NumberVertical Region Change Positions (See Table IX.)
VTPRCP7
HBLKSPTR0–2b0–3 Sequence NumberSequence Pointer for HBLK Regions 0–7
HBLKSPTR7
SEQUENCE CHANGE POSITION #0
SEQUENCE CHANGE POSITION #1
SEQUENCE CHANGE POSITION #2
SEQUENCE CHANGE POSITION #3
UP TO FOUR INDIVIDUAL HORIZONTAL CLAMP AND BLANKING REGIONS MAY BE PROGRAMMED WITHIN A SINGLE FIELD, USING THE SEQUENCE CHANGE POSITIONS.
(V-COUNTER = 0)
SINGLE FIELD (1 VD INTERVAL)
CLAMP AND PBLK SEQUENCE REGION 1
CLAMP AND PBLK SEQUENCE REGION 2
CLAMP AND PBLK SEQUENCE REGION 3
CLAMP AND PBLK SEQUENCE REGION 4
Figure 16. Clamp and Blanking Sequence Flexibility
REV. A–16–
AD9891/AD9895
VERTICAL TIMING GENERATION
The AD9891/AD9895 provide a very flexible solution for generating vertical CCD timing and can support multiple CCDs and
different system architectures. The 4-phase vertical transfer
clocks V1–V4 are used to shift each line of pixels into the horizontal output register of the CCD. The AD9891/AD9895 allow
these outputs to be individually programmed into different pulse
patterns. Vertical sequence control registers then organize the
individual vertical pulses into the desired CCD vertical timing
arrangement.
Figure 17 shows an overview of how the vertical timing is generated in three basic steps. First, the individual pulse patterns or
CREATE THE INDIVIDUAL VERTICAL
SEQUENCES (MAXIMUM OF 12 SEQUENCES).
SEQUENCE 0
SEQUENCE 1
SEQUENCE 2
SEQUENCE 3
SEQUENCE 4
SEQUENCE 5
SEQUENCE 6
SEQUENCE 7
SEQUENCE 8
SEQUENCE 9
SEQUENCE 10
SEQUENCE 11
sequences are created by using the Vertical Transfer Pulse (VTP)
Registers. These sequences are a essentially a “pool” of pulse
patterns that may be assigned to any of the V1-V4 outputs. Second, individual regions are built by assigning a sequence to each
of the V1–V4 outputs. Up to five unique regions may be specified. Finally, the readout of the entire field is constructed by
combining one or more of the individual regions sequentially.
With up to eight region areas available, different steps of the
readout such as high speed line shifts and vertical image transfer
can be supported.
BUILD THE INDIVIDUAL VERTICAL REGIONS BY ASSIGNING
EACH SEQUENCE TO V1–V4 OUTPUTS (MAXIMUM OF 5 REGIONS).
REGION 0 V1 (SEQ 0)
V2 (SEQ 0*)
V3 (SEQ 1)
V4 (SEQ 1*)
REGION 1 V1 (SEQ 2)
V2 (SEQ 3)
V3 (SEQ 4)
V4 (SEQ 5)
BUILD THE ENTIRE FIELD READOUT BY COMBINING
MULTIPLE REGIONS (MAXIMUM OF 8 COMBINATIONS).
USE REGION 2 FOR LINES 1 TO 20
USE REGION 1 FOR LINE 21
USE REGION 0 FOR LINES 22 TO 2000
USE REGION 2 FOR LINES 2001 TO 2020
Figure 17. Summary of Vertical Timing Generation
REGION 4 V1 (SEQ 6)
V2 (SEQ 6*)
V3 (SEQ 7)
V4 (SEQ 7*)
*SEQUENCES MAY BE SHIFTED AND/OR INVERTED
REV. A
–17–
AD9891/AD9895
Individual Vertical Sequences
To generate the individual vertical sequences or patterns shown
in Figure 18, five registers are required for each sequence.
Table VII summarizes these registers and their respective bit
lengths.
polarity of
The start polarity (VTPPOL) determines the starting
the vertical sequence and can be programmed high
or low. The first toggle position (VTPTOG1) and second
toggle position (VTPTOG2) are the pixel locations within the
line
where the pulse transitions. A third toggle position
(VTPTOG3) is also available for sequences 0 through 7. All
toggle positions are 10-bit values, which limits the placement of
a pulse to within 1024 pixels of a line. A separate register,
VSTART, sets the start position of the sequence within the line
(see Individual Vertical Regions section). The Length
(VTPLEN) Register determines the number of pixels between
each of the pulse repetitions, if any repetitions have been
programmed. The number of repetitions (VTPREP) simply
determines the number of pulse repetitions desired within a
single line. Programming “1” for VTPREP gives a single
pulse, while setting to “0” will provide a fixed dc output based
on the start polarity value. There is a total of 12 individual
sequences that may be programmed.
When specifying the individual regions, each sequence may be
assigned to any of the V1–V4 outputs. For example, Figure 19
shows a typical 4-phase V-clock arrangement. Two different
sequences are needed to generate the different pulsewidths.
The use of individual start positions for V1–V4 allows the four
outputs to be generated from two sequences. Figure 20 shows a
slightly different V-clock arrangement in which V2, V3, and V4
are simply shifted and/or inverted versions of V1. Only one
individual sequence is needed because all signals have the same
pulsewidth. The invert sequence registers (VINV) are used for
V3 and V4 (see Table VII).
Note that for added flexibility, the VTPPOL Registers (Start
Polarity) may be used as an extra toggle position.
Table VII. Individual VTP Sequence Parameters
RegisterLengthRangeDescription
VTPPOL1bHigh/LowStarting Polarity of Vertical Transfer Pulse for Each Sequence 0–11
VTPTOG110b0–1023 Pixel LocationFirst Toggle Position within Line for Each Sequence 0–11
VTPTOG210b0–1023 Pixel LocationSecond Toggle Position within Line for Each Sequence 0–11
VTPTOG310b0–1023 Pixel LocationThird Toggle Position within Line for Each Sequence 0–7
VTPLEN10b0–1023 PixelsLength between Pulse Repetitions for Each Sequence 0–11
VTPREP12b0–4095 PulsesNumber of Pulse Repetitions for Each Sequence 0–11 (0 = DC Output)
START POSITION OF SEQUENCE IS INDIVIDUALLY PROGRAMMABLE FOR EACH V1–V4 OUTPUT
HD
5
4
V1–V4
PROGRAMMABLE SETTINGS FOR EACH SEQUENCE:
1: START POLARITY
2: 1ST TOGGLE POSITION
3: 2ND TOGGLE POSITION (THERE IS ALSO A 3RD TOGGLE POSITION AVAILABLE FOR SEQUENCES 0 TO 7)
4: LENGTH BETWEEN REPEATS
5: NUMBER OF REPEATS