LF2272
DEVICES INCORPORATED
DEVICES INCORPORATED
Colorspace Converter/
Corrector (3 x 12-bits)
DESCRIPTION
The
LF2272
is a high-speed digital
colorspace converter/corrector
consisting of three simultaneous 12-bit
input and output channels for func-
tionality up to 64 Giga (2
36
) colors.
Some of the applications the LF2272
can be used for include phosphor
colorimetry correction, image captur-
ing and manipulation, composite color
encoding/decoding, color matching,
and composite color standards
conversion/transcoding.
The 3 x 3 matrix multiplier (triple dot
product) allows users to easily per-
form three-dimensional perspective
translations or video format conver-
sions at real-time video rates. By
using the LF2272, conversions can be
made from the RGB (color compo-
nent) format to the YIQ (quadrature
encoded chrominance) or YUV (color
difference) formats and vice versa
(YIQ or YUV to RGB). Differing signal
formats in each stage of a system can
be disregarded. For example, using
an LF2272 at each format interface
allows each stage of a system to
operate on the data while in the
appropriate format.
Colorspace Converter/
Corrector (3 x 12-bits)
LF2272
FEATURES
u
50 MHz Data and Computation
Rate
u
Full Precision Internal Calculations
with Output Rounding
u
On-board 10-bit Coefficient Storage
u
Overflow Capability in Low
Resolution Applications
u
Two’s Complement Input and
Output Data Format
u
3 Simultaneous 12-bit Channels
(64 Giga Colors)
u
Applications:
• Component Color Standards
Translations (RGB, YIQ, YUV)
• Color-Temperature Conversion
• Image Capturing and Manipulation
• Composite Color Encoding/
Decoding
• Three-Dimensional Perspective
Translation
u
Replaces TRW/Raytheon/Fairchild
TMC2272
u
120-pin PQFP
All inputs and outputs, as well as all
control lines, are registered on the
rising edge of clock. The LF2272
operates at clock rates up to 50 MHz
over the full commercial temperature
and supply voltage ranges. A nar-
rower data path can be used to allow
the LF2272 to work with many
different imaging applications.
DETAILS OF OPERATION
All three input ports (A, B, C) and all
three output ports (X, Y, Z) are
utilized to implement a 3 x 3 matrix
multiplication (triple dot product).
Each truncated 12-bit output is the
sum of all three input words multi-
plied by the appropriate coefficients
(Table 1). The pipeline latency is five
clock cycles. Therefore, the sum of
LF2272 B
LOCK
D
IAGRAM
CLK
CWEL
1-0
2
DATA
INPUTS
{
{
B
11-0
C
11-0
12
12
12
12
Y
11-0
Z
11-0
KA
9-0
KB
9-0
KC
9-0
10
10
10
COEFFICIENT
INPUTS
9-MULTIPLIER
ARRAY
Video Imaging Products
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08/16/2000–LDS.2272-I
{
A
11-0
12
12
X
11-0
DATA
OUTPUTS
LF2272
DEVICES INCORPORATED
Colorspace Converter/
Corrector (3 x 12-bits)
T
ABLE
1.
L
ATENCY
E
QUATIONS
X(n+4) = A(n)KA1(n) + B(n)KB1(n)
Y(n+4) = A(n)KA2(n) + B(n)KB2(n)
Z(n+4)
= A(n)KA3(n) + B(n)KB3(n)
+ C(n)KC1(n)
+ C(n)KC2(n)
+ C(n)KC3(n)
products will be output five clock
cycles after the input data has been
registered. New output data is
subsequently available every clock
cycle thereafter.
DATA FORMATTING
The data input ports (A, B, C) and
data output ports (X, Y, Z) are 12-bit
integer two’s complement format.
The coefficient input ports (KA, KB,
KC) are 10-bit fractional two’s
complement format. Refer to
Figures 1a and 1b.
BIT WEIGHTING
The internal sum of products of the
LF2272 can grow to 23 bits. However,
in order to keep the output format
identical to the input format, the X, Y,
and Z outputs are rounded to 12-bit
integer words. The rounding is done
only at the final output stage to allow
accuracy, with correct rounding and
overflow, for applications requiring
less than 12-bit integer words. The
user may adjust the bit weighting by
applying an identical scaling correc-
tion factor to both the input and
output data streams.
DATA OVERFLOW
Because the LF2272’s matched input
and output data formats accommo-
date unity gain (0 dB), input condi-
tions that could lead to numeric
overflow may exist. To ensure that no
overflow conditions occur, the user
must be aware of the maximum input
data and coefficient word sizes
allowable for each specific algorithm
being performed.
SYSTEMS SMALLER THAN 12-BITS
Using a data path less than 12-bits
requires the input data to be right
justified and sign extended to 12-bits
because the LF2272 carries out all
calculations to full precision. Since all
least-significant bits are used, the
desired X, Y, and Z outputs are
rounded correctly and upper-order
output bits are used for overflow.
F
IGURE
1
A
.
I
NPUT
F
ORMATS
Data Input
11 10 9 8 7
–2
11
2
10
2
9
2
8
2
7
(Sign)
6 5 4 3 2 1 0
2
6
2
5
2
4
2
3
2
2
2
1
2
0
Coefficient Input
9 8 7 6 5 4 3 2 1 0
–2
0
2
–1
2
–2
2
–3
2
–4
2
–5
2
–6
2
–7
2
–8
2
–9
(Sign)
Internal Sum
20 19 18 17
–2
11
2
10
2
9
2
8
(Sign)
3 2 1 0
2
–6
2
–7
2
–8
2
–9
F
IGURE
1
B
.
O
UTPUT
F
ORMAT
Result
11 10 9 8 7
–2
11
2
10
2
9
2
8
2
7
(Sign)
6 5 4 3 2 1 0
2
6
2
5
2
4
2
3
2
2
2
1
2
0
Video Imaging Products
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08/16/2000–LDS.2272-I
LF2272
DEVICES INCORPORATED
Colorspace Converter/
Corrector (3 x 12-bits)
T
ABLE
2. C
OEFFICIENT
I
NPUTS
INPUT PORT
KA
KB
KC
REG. AVAILABLE
KA1, KA2, KA3
KB1, KB2, KB3
KC1, KC2, KC3
SIGNAL DEFINITIONS
Power
V
CC
and GND
+5 V power supply. All pins must be
connected.
Clock
CLK — Master Clock
The rising edge of CLK strobes all
enabled registers. All timing specifi-
cations are referenced to the rising
edge of CLK.
Inputs
A
11-0
, B
11-0
, C
11-0
— Data Inputs
A, B, and C are the 12-bit registered
data input ports. Data presented to
these ports is latched into the multi-
plier input registers.
KA
9-0
, KB
9-0
, KC
9-0
— Coefficient Inputs
KA, KB, and KC are the 10-bit regis-
tered coefficient input ports. Data
presented to these ports is latched into
the corresponding internal coefficient
register set defined by CWEL
1-0
(Table 3) on the next rising edge of
CLK. Table 2 shows which coefficient
registers are available for each coeffi-
cient input port.
T
ABLE
3. C
OEFF
. R
EG
. U
PDATE
CWEL
1
-
0
00
01
10
11
COEFFICIENT SET
Hold All Registers
KA1, KB1, KC1
KA2, KB2, KC2
KA3, KB3, KC3
Outputs
X
11-0
, Y
11-0
, Z
11-0
— Data Outputs
X, Y, and Z are the 12-bit registered
data output ports.
Controls
CWEL
1-0
— Coefficient Write Enable
The registered coefficient write enable
inputs determine which internal
coefficient register set to update
(Table 3) on the next clock cycle.
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LF2272
DEVICES INCORPORATED
Colorspace Converter/
Corrector (3 x 12-bits)
F
IGURE
2. D
ETAILED
F
UNCTIONAL
D
IAGRAM
12
A
KA1
KA
10
KA2
KA3
21
21
21
B
12
KB1
KB
10
KB2
KB3
21
21
21
C
12
KC1
KC
10
KC2
KC3
21
21
21
CWEL
2
12 (MSB)
12 (MSB)
12 (MSB)
X
Y
Z
Video Imaging Products
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08/16/2000–LDS.2272-I
LF2272
DEVICES INCORPORATED
Colorspace Converter/
Corrector (3 x 12-bits)
M
AXIMUM
R
ATINGS
Above which useful life may be impaired (Notes 1, 2, 3, 8)
Storage temperature ........................................................................................................... –65°C to +150°C
Operating ambient temperature ........................................................................................... –55°C to +125°C
V
CC
supply voltage with respect to ground ............................................................................ –0.5 V to +7.0 V
Input signal with respect to ground ............................................................................... –0.5 V to V
CC
+ 0.5 V
Signal applied to high impedance output ...................................................................... –0.5 V to V
CC
+ 0.5 V
Output current into low outputs ............................................................................................................. 25 mA
Latchup current ............................................................................................................................... > 400 mA
O
PERATING
C
ONDITIONS
To meet specified electrical and switching characteristics
Mode
Active Operation, Commercial
Active Operation, Military
Temperature Range
(Ambient)
0°C to +70°C
–55°C to +125°C
Supply
Voltage
4.75 V
≤
V
CC
≤
5.25 V
4.50 V
≤
V
CC
≤
5.50 V
E
LECTRICAL
C
HARACTERISTICS
Over Operating Conditions (Note 4)
Symbol
V
OH
V
OL
V
IH
V
IL
I
IX
I
OZ
I
CC1
I
CC2
C
IN
C
OUT
Parameter
Output High Voltage
Output Low Voltage
Input High Voltage
Input Low Voltage
Input Current
Output Leakage Current
V
CC
Current, Dynamic
V
CC
Current, Quiescent
Input Capacitance
Output Capacitance
(Note 3)
Test Condition
Vcc
= Min.,
I
OH
= –2.0 mA
Vcc
= Min.,
I
OL
= 4.0 mA
Min
2.4
Typ
Max
Unit
V
0.4
2.0
0.0
V
CC
0.8
±10
±40
160
12
10
10
V
V
V
µA
µA
mA
mA
pF
pF
Ground
≤
V
IN
≤
V
CC
(Note 12)
(Note 12)
(Notes 5, 6)
(Note 7)
T
A
= 25°C, f = 1 MHz
T
A
= 25°C, f = 1 MHz
Video Imaging Products
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