LT1675 LINER [Linear Technology], LT1675 Datasheet - Page 16

• Manufacturer Part Number: LT1675
• Description: 250MHz, Triple and Single RGB Multiplexer with Current Feedback Amplifiers
• Manufacturer: LINER [Linear Technology]

LT1675/LT1675-1
TYPICAL
An RGB color bar test pattern is easily generated by
dividing down a suitable clock. To form a stable pattern,
the clock must be synchronous with the horizontal scan
rate. Four times subcarrier, or 14.318MHz, is a readily
available frequency, which when divided by 91, gives
157.343KHz. Dividing this signal by two, four and eight,
gives the blue, read and green signals, respectively. This
timing gives eight bars including white and black that fill
the 52.6 s active video time. The digital signals are run
RELATED PARTS
PART NUMBER
LT1203/LT1205
LT1204
LT1260
LT1398/LT1399
16
SUBCARRIER 4
OR 157.343kHz
DIVIDED BY 91
0.714V
0.714V
0.714V
CLOCK IS
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone] FAX: [phone] www.linear-tech.com
R
G
B
0
0
0
COMPOSITE
APPLICATION
BLANKING
DESCRIPTION
150MHz Video MUX
4-Input Video MUX with 75MHz Current Feedback Amp
Low Cost Dual and Triple 130MHz Current Feedback Amp
with Shutdown
Low Cost Dual and Triple 300MHz Current Feedback Amp
with Shutdown
5V
D
A
B
C
CLR
CLK
LOAD
74LS163
ENP
5V
ENT
U
QA
QB
QC
74ACT04
NTSC-Related Color Bar Generator
640
10k
6.04k
6.04k
6.04k
–5V
–0.285V
G
B
1k
1k
R
through a 74ACT04 inverter because the CMOS output
swings rail-to-rail. The inverter output is scaled to make
video (0.714V peak, for NTSC-related RGB). The LT1675
drives the cable and adds sync to the RGB signals by
switching in –0.286V. If no sync is required, this voltage
can be set to zero and composite blanking can be used to
drive the select pin of the LT1675 in order to provide a
more precise blanking level.
1k
COMMENTS
2-Input and 4-Input, 90dB Channel Separation, Wide Supply Range
Drives Cables, Adjustable Gain, 90dB Channel Separation
Drives Cables, Wide Supply Range, 0 A Shutdown Current
Performance Upgrade for the LT1259/LT1260
+1
+1
+1
+1
+1
+1
LT1675
COMPOSITE
16751fs, sn16751 LT/TP 0199 4K • PRINTED IN USA
SYNC
+2
+2
+2
LINEAR TECHNOLOGY CORPORATION 1998
75
75
75
V
SELECT
ENABLE
+
V
CABLE
CABLE
CABLE
–
75
75
75
V
V
V
OUT BLUE
OUT RED
OUT GREEN
1675 TA04