Datasheet

AD9984A
Rev. 0 | Page 20 of 44
DATAIN
P0 P1 P2 P5P3 P4 P9P6 P8 P10 P11P7
HSYNCx
DATACK
8 CLOCK CYCLE DELAY
DATAOUT
P0 P1 P2 P3
2 CLOCK CYCLE DELAY
HSOUT
06476-014
Figure 15. 4:4:4 Timing Mode
DATAIN
HSYNCx
DATACK
8 CLOCK CYCLE DELAY
Cb/CrOUT
YOUT
2 CLOCK CYCLE DELAY
HSOUT
NOTES
1. PIXEL AFTER HSOUT CORRESPONDS TO BLUE INPUT.
2. EVEN NUMBER OF PIXEL DELAY BETWEEN HSOUT AND DATAOUT.
P0 P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11
Y0
CB0 CR0 CB2 CR2
Y1 Y2 Y3
06476-015
Figure 16. 4:2:2 Timing Mode
DATAIN P0 P1 P2 P5
P3 P4
P9P6
P8 P10 P11P7
HSYNCx
DATAC
K
8 CLOCK CYCLE DELAY
2 CLOCK CYCLE DELAY
DDR NOTES
1. OUTPUT DATACK MAY BE DELAYED 1/4 CLOCK PERIOD IN THE REGISTERS.
2. SEE PROJECT DOCUMENT FOR VALUES OF F (FALLING EDGE) AND R (RISING EDGE).
3. FOR DDR 4:2:2 MODE: TIMING IS IDENTICAL, VALUES OF F AND R CHANGE.
GENERAL NOTES
1. DATA DELAY MAY VARY ± ONE CLOCK CYCLE, DEPENDING ON PHASE SETTING.
2. ADCs SAMPLE INPUT ON FALLING EDGE OF DATACK.
3. HSYNC SHOWN IS ACTIVE HIGH (EDGE SHOWN IS LEADING EDGE).
HSOUT
F0 R0 F1 R1 F2 R2 F3 R3
06476-016
Figure 17. Double Data Rate (DDR) Timing Mode
HSYNC TIMING
The Hsync is processed in the AD9984A to eliminate ambiguity
in the timing of the leading edge with respect to the phase-
delayed pixel clock and data.
The Hsync input is used as a reference to generate the pixel
sampling clock. The sampling phase can be adjusted with
respect to Hsync through a full 360° in 32 steps via the phase
adjust register (to optimize the pixel sampling time). Display
systems use Hsync to align memory and display write cycles.
Therefore, it is important to have a stable timing relationship
between the Hsync output (HSOUT) and data clock (DATACK).
Three things happen to Hsync in the AD9984A. First, the
polarity of Hsync input is determined and, as a result, has a
known output polarity. The known output polarity can be
programmed either active high or active low (Register 0x12,
Bit 3). Second, HSOUT is aligned with DATACK and data
outputs. Third, the duration of HSOUT (in pixel clocks) is set
via Register 0x13. HSOUT is the sync signal that should be used
to drive the rest of the display system.