FMS9875
PRODUCT SPECIFICATION
REV. 1.2.15 1/14/02
27
Figure 26. Recommended Power Distribution
VPLL
Power Input
Pin 39
Pin 37
Pin 33
Pins
26, 27
VADC Pins
VDD Pins
C4
0.1
μ
F
C5
10
μ
F
L1
BEAD
BEAD
BEAD
L2
L3
U1
RC1117-3.3
3
1
1
2
4
OUT
OUT
IN
ADJ/GND
OUT
OUT
IN
ADJ/GND
U2
RC1117-3.3
3
2
4
C3
0.01
μ
F
C2
0.1
μ
F
C1
0.01
μ
F
+
+
C24
10
μ
F
C25
10
μ
F
+
C7
10
μ
F
C23
0.1
μ
F
C6
0.1
μ
F
C8
0.1
μ
F
C9
0.1
μ
F
C10
0.1
μ
F
C11
0.1
μ
F
C12
0.1
μ
F
C13
0.1
μ
F
C14
0.1
μ
F
C15
0.1
μ
F
C16
0.1
μ
F
C17
0.1
μ
F
C18
0.1
μ
F
C19
0.1
μ
F
C20
0.1
μ
F
C21
0.1
μ
F
C22
0.1
μ
F
Physical placement of PLL power supply decoupling
components is critical. Bearing in mind the following
suggestions:
1.
All components should be placed in close proximity to
the FMS9875 pins.
2.
Routing through vias should be avoided, if possible.
3.
Each V
DDP
/GND pin pair: 26&27/28, 33/32, 37/38, and
39/40 should be decoupled with a either a 0.01 or 0.1 μF
capacitor (see Figure 24).
4.
Use Fair-rite 274 301 9447 bead.
Firmware
Best performance can be achieved by correctly setting the
FMS9875 registers. Here are some recommendations:
1.
For analog video, the sampling rate is usually 2X–3X
the video bandwidth. PLLN and PHASE are not critical.
For PC video, set the value of PLLN equal to the num-
ber of pixels to be sampled minus one. With this setting,
the number of samples per horizontal line equals the
number of pixels. If PLLN + 1 does not equal the num-
ber of pixels, there will be irregular intensities on text
and an interference pattern on a vertical grill pattern.
In the GBR mode, calibrate Offset and Gain by first set-
ting each input to 0mV. Then adjust OSGY, OSBP, and
OSRP to set each RGB data output D
7-0
= 0x00. Next
2.
3.
with 700mV input, adjust GGY, GBP and GRP so that
each RGB data output D
7-0
= (same value), typically
240 decimal. Average values during calibration to
minimize the impact of noise.
In the YP
B
P
R
mode, the Y-channel calibration procedure
is the same as for GBR. P
B
P
R
channels must be
calibrated differently. If the internal mid-scale clamp is
used, Offset is automatically preset. Only the Gain need
be adjusted to accomodate the swing from peak blue to
peak orange on the P
B
channel; and peak red to peak
cyan onthe P
R
channel. Average values during calibra-
tion to minimize the impact of noise.
Clamp registers, CD and CW, should be programmed to
maximize the period of the clamp during the backporch,
while not encroaching into the sync or active video
periods.
PHASE must be trimmed to minimize onscreen snow
(intensity noise) when a vertical grill pattern is
displayed.
FVCO must be set to encompass the incoming
frequency range.
IPUMP must be set to minimize intensity noise.
To ensure correct power-on defaults, program all regis-
ters including Test Register 0x0F, which must be set to
0x00 for normal operation. Note that unlike registers
0x00 through 0x0D, register 0x0F does not acknowl-
edge. The ACK bit remains H instead of being pulled L.
4.
5.
6.
7.
8.
9.