Datasheet

8
LT1203/LT1205
U
S
A
O
PP
L
IC
AT
I
WU
U
I FOR ATIO
CMOS MUX Channel-to-Channel Switching Transient
OUTPUT
1V/DIV
LT1203/05 • AI02
R
S
= 50
NOTE: 50 TIMES LARGER THAN LT1203 TRANSIENT
LT1203/05 • AI03
OUTPUT
(PIN 7)
CHANNEL 1 = 0V
CHANNEL 2 = 2MHz SINEWAVE
LOGIC
(PIN 5)
LT1203 Switching Inputs
only 10mV
P-P
. A photo of the switching transients from a
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.
+1
1
2
3
4
5
6
7
8
16
15
14
13
1
2
3
4
8
7
6
5
12
1
16
15
14
13
12
11
10
9
2
3
4
5
6
7
8
LT1260
11
10
9
+1
+1
+1
LT1205
LT1203/05 • F01
+1
+1
LT1203
R4
75
J4
GREEN 2
J7
LOGIC
R6
75
C1
0.1µF
C2
0.1µF
C3
4.7µF
C4
4.7µF
J6
BLUE 2
R8*
10k
R13
1.5k
R15
1.5k
R9*
10k
*OPTIONAL
R14
1.5k
R7*
10k
R5
75
J5
BLUE 1
R3
75
J3
GREEN 1
R2
75
J2
RED 2
R1
75
J1
RED 1
+
+
+
R12
1.5k
R10
1.5k
V
+
V
R11
1.5k
R
G
B
+
+
GND
J8
ENABLE
J9
RED
J10
GREEN
J11
BLUE
R16
75
R17
75
R18
75
Figure 1. RGB MUX
INPUT
1V/DIV
LOGIC
CONTROL