LT1205 Linear Technology Corporation, LT1205 Datasheet - Page 8

• Manufacturer Part Number: LT1205
• Description: 150mhz Video Multiplexers
• Manufacturer: Linear Technology Corporation

LT1203/LT1205
A
8
CONTROL
OUTPUT
OUTPUT
PPLICATI
(PIN 5)
(PIN 7)
1V/DIV
1V/DIV
INPUT
LOGIC
LOGIC
CMOS MUX Channel-to-Channel Switching Transient
CHANNEL 1 = 0V
CHANNEL 2 = 2MHz SINEWAVE
R
NOTE: 50 TIMES LARGER THAN LT1203 TRANSIENT
J1
RED 1
S
= 50
R1
75
J2
RED 2
O
LT1203 Switching Inputs
R2
75
U
J5
BLUE 1
S
J3
GREEN 1
R5
75
R3
75
I FOR ATIO
U
J6
BLUE 2
J4
GREEN 2
+
4.7 F
R6
75
C4
R4
75
W
C1
0.1 F
1
2
3
4
5
6
7
8
1
2
3
4
+1
+1
+1
+1
+1
+1
LT1205
LT1203
LT1203/05 • AI02
LT1203/05 • AI03
U
4.7 F
C3
16
15
14
13
12
11
10
9
8
7
6
5
Figure 1. RGB MUX
+
0.1 F
C2
J8
ENABLE
only 10mV
CMOS MUX shows glitches to be 50 times larger than on
the LT1203. Also shown is the output of the LT1203
switching on and off a 2MHz sinewave cleanly and without
abnormalities.
Pixel Switching
The multiplexers are fabricated on LTC's Complementary
Bipolar Process to attain fast switching speed, high band-
width, and a wide supply voltage range compatible with
traditional video systems. Channel-to-channel switching
time and Enable time are both 25ns, therefore delay is the
same when switching between channels or between ICs.
To demonstrate the switching speed of the LT1203/LT1205
the RGB MUX of Figure 1 is used to switch RGB Worksta-
tion inputs with a 22ns pixel width. Figure 2a is a photo
showing the Workstation output and RGB MUX output.
The slight rise time degradation at the RGB MUX output is
due to the bandwidth of the LT1260 current feedback
amplifier used to drive the 75 cable. In Figure 2b, the
LT1203 switches to an input at zero at the end of the first
pixel and removes the following pixels.
J7
LOGIC
R7*
10k
R8*
10k
R9*
10k
1.5k
1.5k
R12
R14
*OPTIONAL
R13
1.5k
P-P
R11
1.5k
R15
1.5k
. A photo of the switching transients from a
1
2
3
4
5
6
7
8
R10
1.5k
–
+
–
+
+
–
LT1260
R
G
B
16
15
14
13
12
11
10
9
LT1203/05 • F01
V
+
V
–
75
75
75
R16
R17
R18
GND
J9
RED
J10
GREEN
J11
BLUE