LF3320QC15 LODEV [LOGIC Devices Incorporated], LF3320QC15 Datasheet - Page 12

• Manufacturer Part Number: LF3320QC15
• Description: Horizontal Digital Image Filter
• Manufacturer: LODEV [LOGIC Devices Incorporated]

DEVICES INCORPORATED
the reverse data path. The device must
see a HIGH to LOW transition of
TXFRA/TXFR B in order to switch
LIFOs. If decimating by N,
TXFRA/TXFRB should go LOW once
every N clock cycles. When data
reversal is disabled, the circuitry
functions like an I/D Register. When
feeding interleaved data through the
filter, data reversal should be disabled.
Bit 6 of Configuration Register 1 and
F
F
IGURE
IGURE
DIN
12
14. D
15. M
TXFRA/TXFRB
REGISTERS
FILTER
LIFO A
LIFO B
ATA
I/D
ULTIPLE
A
LF3320
CIRCUIT
16
RSL
R
REGISTERS
EVERSAL
FILTER
I/D
B
LF3320
RIN
COUT
S
ROUT
C
DIN
ASCADED
Configuration Register 3 enables or
disables data reversal for Filters A
and B respectively.
Cascading
Three cascade ports are provided to
allow cascading of multiple devices for
more filter taps (see Figure 15).
COUT
connected to DIN
ROUT
connected to RIN
As many LF3320s as desired may be
cascaded together. However, the
outputs of the LF3320s must be added
together with external adders.
Bit 0 of Configuration Register 5 deter-
mines how the device will send data to
the reverse data path when multiple
LF3320s are cascaded together. If a
LF3320 is the last in the cascade chain,
Bit 0 of Configuration Register 5 should
be set to a “0”. This will cause the data
from the end of the forward data path to
be routed to the beginning of the
reverse data path based on how the
REGISTERS
FILTER
I/D
A
LF3320
11-0
CIRCUIT
11-0
16
RSL
T
REGISTERS
of one device should be
of one device should be
OGETHER
FILTER
I/D
B
11-0
11-0
128 TAP RESULT
2-12
RIN
COUT
25
LF3347
DATA OUT
CIRCUIT
16
of another device.
of another device.
RSL
ROUT
DIN
25
REGISTERS
FILTER
I/D
A
LF3320
CIRCUIT
16
Horizontal Digital Image Filter
RSL
REGISTERS
FILTER
I/D
B
filter is configured (even/odd number
of taps or interleave mode). If a LF3320
is not the last in the cascade chain, Bit 0
of Configuration Register 5 should be set
to a “1”. This will cause RIN
data to the reverse data path. When
not cascading, Bit 0 of Configuration
Register 5 should be set to a “0”.
Special data routing circuitry is used to
feed the COUT and ROUT output
registers. The data routing circuitry is
required to correctly align data in the
forward and reverse data paths as data
passes from one LF3320 to another.
The COUT and ROUT registers are
loaded with data which is two clock
cycles behind the current output of the
I/D Register just before the ROUT or
COUT register. This correctly accounts
for the extra delays added to the forward
and reverse data paths by the
input/output cascade registers.
Video Imaging Products
RIN
COUT
ROUT
DIN
REGISTERS
FILTER
I/D
A
LF3320
CIRCUIT
16
RSL
REGISTERS
FILTER
08/16/2000–LDS.3320-N
I/D
B
LF3320
11-0
to feed