LT1203CS8#PBF [Linear]
LT1203 - 150MHz Video Multiplexers; Package: SO; Pins: 8; Temperature Range: 0°C to 70°C;
| 型号： | LT1203CS8#PBF |
| 厂家： | 
Linear |
| 描述： | LT1203 - 150MHz Video Multiplexers; Package: SO; Pins: 8; Temperature Range: 0°C to 70°C 复用器 光电二极管 |
| 文件： | 总16页 (文件大小：561K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LT1203/LT1205
150MHz Video Multiplexers
U
DESCRIPTIO
EATURE
S
F
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The LT1203 is a wideband 2-input video multiplexer
designed for pixel switching and broadcast quality rout-
ing. The LT1205 is a dual version that is configured as a
4-input, 2-output multiplexer.
–3dB Bandwidth: 150MHz
0.1dB Gain Flatness: 30MHz
Channel-to-Channel Switching Time: 25ns
Turn-On/Turn-Off Time: 25ns
High Slew Rate: 300V/µs
These multiplexers act as SPDT video switches with 10ns
transition times at toggle rates up to 30MHz. The –3dB
bandwidth is 150MHz and 0.1dB gain flatness is 30MHz.
Many parts can be tied together at their outputs by using
the enable feature which reduces the power dissipation
and raises the output impedance to 10MΩ. Output capaci-
tancewhendisabledisonly3pFandtheLT1203peaksless
than 3dB into a 50pF load. Channel crosstalk and disable
isolation are greater than 90dB up to 10MHz. An on-chip
buffer interfaces to fast TTL or CMOS logic. Switching
transients are only 50mV with a 25ns duration. The
LT1203 and LT1205 outputs are protected against shorts
to ground.
Disabled Output Impedance: 10MΩ
50mV Switching Transient
Channel Separation at 10MHz: >90dB
Differential Gain: 0.02%
Differential Phase: 0.02°
Wide Supply Range: ±5V to ±15V
Output Short-Circuit Protected
Push-Pull Output
O U
PPLICATI
S
A
■
■
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■
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■
Broadcast Quality Video Multiplexing
Picture-in-Picture Switching
HDTV
Computer Graphics
Title Generation
Video Crosspoint Matrices
Video Routers
The LT1203/LT1205 are manufactured using Linear
Technology’sproprietarycomplementarybipolarprocess.
The LT1203 is available in both the 8-lead PDIP and SO
package while the LT1205 is available in the 16-lead
narrow body SO package.
U
O
TYPICAL APPLICATI
Large-Signal Response
High Speed RGB MUX
CHANNEL SELECT
+
V
RED 1
+1
+1
+1
+1
V
RED
OUT
OUT
EN
RED 2
LOGIC
–
LT1205
V
+
V
GREEN 1
V
GREEN
EN
GREEN 2
LOGIC
–
V
+
V
BLUE 1
+1
+1
LT1203
V
BLUE
OUT
EN
BLUE 2
LOGIC
–
V
LT1203 • TA01
1
LT1203/LT1205
W W W
U
ABSOLUTE AXI U RATI GS
Supply Voltage ...................................................... ±18V
Signal Input Current (Note 1) ............................ ±20mA
Logic Input Current (Note 2).............................. ±50mA
Output Short-Circuit Duration (Note 3)........ Continuous
Specified Temperature Range (Note 4)....... 0°C to 70°C
Operating Temperature Range ............... –40°C to 85°C
Storage Temperature Range ................ –65°C to 150°C
Junction Temperature (Note 5)............................ 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
W
U
/O
PACKAGE RDER I FOR ATIO
TOP VIEW
ORDER PART
ORDER PART
+
V
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
V
NUMBER
INO
NUMBER
TOP VIEW
GND
V
OUT1
+
V
1
2
3
4
V
V
8
7
6
5
IN0
V
EN1
IN1
LT1203CN8*
LT1203CS8*
LT1205CS*
GND
OUT
–
V
LOGIC 1
+
V
EN
IN1
V
V
IN2
–
V
LOGIC
GND
V
OUT2
N8 PACKAGE
S8 PACKAGE
V
EN2
IN3
S8 PART MARKING
1203
8-LEAD PLASTIC DIP 8-LEAD PLASTIC SOIC
–
V
LOGIC 2
TJMAX = 150°C, θJA = 100°C/W (N)
S PACKAGE
16-LEAD PLASTIC SOIC
T
JMAX = 150°C, θJA = 150°C/W (S)
TJMAX = 150°C, θJA = 100°C/W
*See Note 4
Consult factory for Industrial and Military grade parts.
ELECTRICAL CHARACTERISTICS
0°C ≤ TA ≤ 70°C, ±5V ≤ VS ≤ ±15V, RL = 1k, pulse tested, EN pin open or high, unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
10
MAX
30
UNITS
V
OS
Output Offset Voltage
Output Offset Matching
Output Offset Drift
Input Current
Any Input Selected
Between Outputs
●
●
●
●
mV
mV
0.3
40
5
∆V /∆T
OS
µV/°C
µA
I
0.6
5
IN
R
IN
Input Resistance
V = ±5V, V = ±2V
●
●
1
2
5
5
MΩ
MΩ
S
IN
V = ±15V, V = ±2V
S
IN
C
IN
Input Capacitance
Input Selected
Input Deselected
2.6
2.6
pF
pF
C
V
Disabled Output Capacitance
Input Voltage (Note 1)
EN Pin Voltage ≤ 0.8V
2.8
pF
OUT
V = ±5V
●
●
±2
±2
±2.8
±3.0
V
V
IN
S
V = ±15V
S
PSRR
Power Supply Rejection Ratio
Gain Error
V = ±4.5 to ±15V
●
60
70
dB
S
V = ±15V, V = ±2V, R = 1k
●
●
●
2
6
3
4
10
6
%
%
%
S
IN
L
V = ±15V, V = ±2V, R = 400Ω
S
IN
L
V = ±5V, V = ±2V, R = 1k
S
IN
L
2
LT1203/LT1205
ELECTRICAL CHARACTERISTICS
0°C ≤ TA ≤ 70°C, ±5V ≤ VS ≤ ±15V, RL = 1k, pulse tested, EN pin open or high, unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
V = ±15V, V = ±2V, R = 400Ω
MIN
TYP
MAX
UNITS
V
OUT
Output Voltage
●
●
±1.8
±1.8
±1.90
±1.94
V
V
S
IN
L
V = ±5V, V = ±2V, R = 1k
S
IN
L
Overload Swing (Note 1)
Output Current
V = ±15V, V = ±5V
●
●
±0.9
±0.9
±1.5
±1.5
V
V
S
IN
V = ±5V, V = ±5V
S
IN
I
V = ±15V, V = ±2V, R = 400Ω
●
●
±4.5
±1.8
±4.75
±2.00
mA
mA
OUT
S
IN
L
V = ±5V, V = ±2V, R = 1k
S
IN
L
R
OUT
Enabled Output Resistance
Disabled Output Resistance
EN Pin Voltage = 2V, V
EN Pin Voltage = 0.5V, V
= ±2V, V = ±15V
●
●
20
10
42
Ω
MΩ
OUT
S
= ±2V, V = ±15V
1
OUT
S
I
Supply Current (LT1203)
EN Pin Voltage = 2V
EN Pin Voltage = 0.5V
●
●
10.0
5.8
14
8
mA
mA
S
Supply Current (LT1205)
EN Pin Voltage = 2V
EN Pin Voltage = 0.5V
●
●
20.0
11.6
28
16
mA
mA
V
V
Logic Low
Logic Pin
Logic Pin
EN Pin
●
●
●
●
●
●
●
0.8
V
V
IL
Logic High
2
2
IH
Enable Low
0.5
V
Enable High
EN Pin
V
I
I
I
Digital Input Current Low
Digital Input Current High
Enable Pin Current
LT1203 Pin 5, LT1205 Pins 9, 13 = 0V
LT1203 Pin 5, LT1205 Pins 9, 13 = 5V
LT1203 Pin 6, LT1205 Pins 10, 14
1.5
10
20
6.5
200
80
µA
nA
µA
IL
IH
EN
TA = 25°C, VS = ±15V, RL = 1k, EN pin open or high, unless otherwise noted.
AC CHARACTERISTICS
SYMBOL PARAMETER
CONDITIONS
MIN
180
TYP
300
47.7
25
MAX
UNITS
V/µs
MHz
ns
SR
Slew Rate (Note 6)
FPBW
Full Power Bandwidth (Note 7)
V
= 2V
28.6
OUT
P-P
t
Channel-to-Channel Select Time (Note 8) R = 10k
35
35
35
SEL
L
Enable Time (Note 9)
Disable Time (Note 9)
Small-Signal Rise and Fall Time
Propagation Delay
R = 1k
25
ns
L
R = 1k
L
20
ns
t , t
r
V
V
V
= 250mV , 10% to 90%
2.6
2.9
5
ns
f
OUT
OUT
OUT
P-P
= 250mV
= 250mV
ns
P-P
P-P
Overshoot
%
Crosstalk (Note 10)
R = 10Ω
S
90
dB
Chip Disabled Crosstalk (Note 10)
Channel Select Output Transient
Settling Time
R = 10Ω, EN Pin Voltage ≤ 0.8V
110
50
dB
L
All V = 0V
mV
P-P
IN
t
1%, V
= 1V
30
ns
S
OUT
Differential Gain (Note 11)
Differential Phase (Note 11)
Insertion Loss
V = ±15V, R = 10k
0.02
0.02
0.02
%
S
L
V = ±15V, R = 10k
DEG
dB
S
L
R = 100k, C = 30pF, V
= 500mV , f = 1MHz
P-P
L
L
OUT
The
●
denotes specifications which apply over the specified
For inputs ≤±2.8V the SCR will not fire. Voltages above 2.8V will fire the
SCR and the DC current should be limited to 20mA. To turn off the SCR
the pin voltage must be reduced to less than 1V or the current reduced to
less than 600µA.
temperature range.
Note 1: The analog inputs (pins 1, 3 for the LT1203, pins 1, 3, 5, 7 for the
LT1205) are protected against ESD and overvoltage with internal SCRs.
3
LT1203/LT1205
Note 2: The digital inputs (pins 5, 6 for the LT1203, pins 9, 10, 13, 14 for
the LT1205) are protected against ESD and overvoltage with internal
SCRs. For inputs ≤±6V the SCR will not fire. Voltages above 6V will fire
the SCR and the DC current should be limited to 50mA. To turn off the
SCR the pin voltage must be reduced to less than 2V or the current
reduced to less than 10mA.
to pin 1 and measure the time for disappearance of 0.5V at pin 7 when
pin 5 goes from 0V to 5V. Apply 1VDC to pin 3 and measure the time for
the appearance of 0.5V at pin 7 when pin 5 goes from 0V to 5V. Apply
1VDC to pin 3 and measure the time for disappearance of 0.5V at pin 7
when pin 5 goes from 5V to 0V. For the LT1205 the same test is
performed on both MUXs.
Note 3: A heat sink may be required depending on the power supply
voltage.
Note 4: Commercial grade parts are designed to operate over the
temperature range of –40°C to 85°C but are neither tested nor guaranteed
beyond 0°C to 70°C. Industrial grade parts specified and tested over
–40°C to 85°C are available on special request, consult factory.
Note 9: For the LT1203, apply 1VDC to pin 1 and measure the time for the
appearance of 0.5V at pin 7 when pin 6 goes from 0V to 5V. Pin 5 voltage
= 0V. Apply 1VDC to pin 1 and measure the time for disappearance of 0.2V
at pin 7 when pin 6 goes from 5V to 0V. Pin 5 voltage = 0V. Apply 1VDC
to pin 3 and measure the time for the appearance of 0.5V at pin 7 when
pin 6 goes from 0V to 5V. Pin 5 voltage = 5V. Apply 1VDC to pin 3 and
measure the time for disappearance of 0.2V at pin 7 when pin 5 goes from
5V to 0V. Pin 5 voltage = 5V. For the LT1205 the same test is performed
on both MUXs.
Note 5: T is calculated from the ambient temperature T and the power
J
A
dissipation P according to the following formulas:
D
LT1203CN8: T = T + (P × 100°C/W)
J
A
D
Note 10: V = 0dBm (0.223V
) at 10MHz on one input with the other
RMS
IN
LT1203CS8: T = T + (P × 150°C/W)
J
A
D
input selected and R = 10Ω. For disable crosstalk all inputs are driven
S
LT1205CS: T = T + (P × 100°C/W)
J
A
D
simultaneously. In disable the output impedance is very high and signal
couples across the package; the load impedance determines the crosstalk.
Note 11: Differential gain and phase are measured using a Tektronix
TSG120 YC/NTSC signal generator and a Tektronix 1780R video
measurement set. The resolution of this equipment is 0.1% and 0.1°.
Ten identical MUXs were cascaded giving an effective resolution of
0.01% and 0.01°.
Note 6: Slew rate is measured at ±2.0V on a ±2.5V output signal while
operating on ±15V supplies, R = 1k.
L
Note 7: Full power bandwidth is calculated from the slew rate
measurement:
FPBW = SR/2πV
PEAK
Note 8: For the LT1203, apply 1VDC to pin 1 and measure the time for the
appearance of 0.5V at pin 7 when pin 5 goes from 5V to 0V. Apply 1VDC
TRUTH TABLE
LOGIC
EN
V
OUT
0
1
V
V
IN0
IN1
1
1
0
0*
0
HIGH Z
HIGH Z
OUT
OUT
1
*Must be ≤0.5V
W U
TYPICAL PERFOR A CE CHARACTERISTICS
±5V Frequency Response
±15V Frequency Response
5
4
3
2
0
5
4
3
2
0
V
T
R
= ±15V
= 25°C
V
T
= ±5V
S
A
S
A
R
–20
–40
–60
–20
–40
–60
= 25°C
= ∞
L
= ∞
L
1
0
–80
1
0
–80
–100
–100
–1
–2
–3
–4
–5
–120
–140
–160
–180
–200
–1
–2
–3
–4
–5
–120
–140
–160
–180
–200
1
10
100
1000
1
10
100
1000
FREQUENCY (MHz)
FREQUENCY (MHz)
LT1203/05 • TPC02
LT1203/05 • TPC01
4
LT1203/LT1205
W U
TYPICAL PERFOR A CE CHARACTERISTICS
–3dB Bandwidth
vs Supply Voltage
Frequency Response
with Capacitive Loads
Crosstalk Rejection
vs Frequency
5
4
–30
–40
–50
200
180
160
140
120
V
T
= ±15V
= 25°C
V
T
= ±15V
= 25°C
T
= 25°C
= 10k
S
A
S
A
A
L
R
C
= 20pF
L
R
= ∞
L
R
= ∞
L
PEAKING ≤ 0.5dB
3
C
= 50pF
C
L
= 10pF
L
2
C
= 100pF
L
–60
–70
1
R
S
= 75Ω
0
R
S
= 37.5Ω
–1
–2
–3
–4
–5
–80
R
= 0Ω
S
R
S
= 10Ω
–90
–100
–110
6
8
10 12 14 16
1
10
FREQUENCY (MHz)
100
1
10
FREQUENCY (MHz)
100
0
2
4
18
SUPPLY VOLTAGE (±V)
LT1203/05 • TPC04
LT1203/05 • TPC05
LT1203/05 • TPC03
Crosstalk Rejection
vs Frequency
Disable Rejection
vs Frequency
Power Supply Rejection Ratio
vs Frequency
–30
–40
–50
–20
–30
70
60
50
40
30
20
10
0
T
R
R
= 25°C
V
T
= ±15V
= 25°C
V
T
= ±15V
A
S
L
S
A
S
= 0Ω
= 25°C
A
=
∞
R
= ∞
–40
–50
L
–PSRR
R
= 0Ω
S
R
= ∞
L
–60
–70
–60
–70
+PSRR
R
= 1k
L
–80
–80
V
= ±5V
S
V
= ±15V
–90
S
–90
–100
–110
R
= 100Ω
L
–100
–110
–120
R
= 10Ω
L
1
10
FREQUENCY (MHz)
100
1
10
FREQUENCY (MHz)
100
1
100
10
FREQUENCY (MHz)
LT1203/05 • TPC07
LT1203/05 • TPC06
LT1203/05 • TPC08
Supply Current
vs Supply Voltage (Disabled)
Output Impedance (Enabled)
vs Frequency
Supply Current
vs Supply Voltage (Enabled)
5.2
5.0
4.8
4.6
4.4
9.6
9.2
8.8
8.4
8.0
7.6
100
80
V
= ±15V
= 25°C
LT1203
L
LT1203
L
S
A
T
R
=
∞
R = ∞
125°
25°
60
25°
–55°
40
30
125°
–55°
20
10
10k
0
2
4
6
8
10 12 14 16 18
0
2
4
6
8
10 12 14 16 18
100k
1M
10M
100M
SUPPLY VOLTAGE (±V)
SUPPLY VOLTAGE (±V)
FREQUENCY (Hz)
LT1203/05 • TPC10
LT1203/05 • TPC11
LT1203/05 • TPC09
5
LT1203/LT1205
W U
TYPICAL PERFOR A CE CHARACTERISTICS
Gain Error vs Temperature
Input Bias Current vs Input Voltage
Output Voltage vs Input Voltage
4
3
8
7
1.2
1.0
0.8
0.6
0.4
0.2
0
V
T
= ±15V
= 25°C
= 1k
V
= ±15V
V
V
= ±15V
IN
S
S
S
R
= ∞
L
= –2V TO 2V
A
R
L
125°C
25°C
R
= 400Ω
L
2
6
5
4
3
2
1
–55°C
0
–1
–2
–3
–4
R
= 1k
25
L
–0.2
–0.4
1
50
100 125
0
1
–50 –25
0
75
–4 –3 –2 –1
2
3
4
–5 –4 –3 –2 –1
0
1
2
3
4
5
TEMPERATURE (°C)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
LT1203/05 • TPC12
LT1203/05 • TPC13
LT1203/05 • TPC14
Settling Time to 1mV and 10mV
vs Output Step
Small-Signal Rise Time
2.0
1.5
1.0
0.5
0
V
= ±15V
= 1k
S
L
R
10mV 1mV
–0.5
–1.0
–1.5
–2.0
1mV
10mV
0
100
200
300
400
500
SETTLING TIME (ns)
LT1203/05 • TPC16
RL = 1k
LT1203/05 • TPC15
VIN1 to VIN0 Select Time
VIN0 to VIN1 Select Time
LOGIC
(PIN 5)
LOGIC
(PIN 5)
VOUT
(PIN 7)
VOUT
(PIN 7)
LT1203/05 • TPC17
LT1203/05 • TPC18
VS = ±15V VINO = 1V
VS = ±15V
VINO = 1V
RL = 10k
VIN1 = 0V
RL = 10k VIN1 = 0V
6
LT1203/LT1205
W U
TYPICAL PERFOR A CE CHARACTERISTICS
Channel 1 Enable
Channel 1 Disable
EN
(PIN 6)
EN
(PIN 6)
VOUT
(PIN 7)
VOUT
(PIN 7)
LT1203/05 • TPC19
LT1203/05 • TPC20
VINO = 1V
VIN1 = 0V
V
INO = 1V
VS = ±15V
L = 1k
VS = ±15V
L = 1k
R
R
VIN1 = 0V
O U
W
U
PPLICATI
A
S I FOR ATIO
with ground plane to ensure high channel separation. For
minimum peaking, maximum bandwidth and maximum
gain flatness sockets are not recommended because they
can add considerable stray inductance and capacitance. If
a socket must be used, use a low profile, low capacitance
socket such as the SamTec ISO-308.
Input Protection
The logic inputs have ESD protection (≥2kV) and short-
ing them to 12V or 15V will cause excessive current to
flow. Limit the current to less than 50mA when driving
the logic above 6V. The analog inputs are protected
against ESD and overvoltage with internal SCRs. For
inputs ≥±2.8V the SCRs will fire and the DC current
should be limited to 20mA.
Switching Transients
TheLT1203/LT1205useinputbufferstoensureswitching
transients do not couple to other video equipment sharing
the input line. Output switching transients are about
50mVP-P with a 20ns duration and input transients are
Power Supplies
The LT1203/LT1205 will operate from ±5V (10V total) to
±15V (30V total) and is specified over this range. Charac-
teristics change very little over this voltage range. It is not
necessaryto useequalvaluesupplies however, the output
offset voltage will change. The offset will change about
300µV per volt of supply mismatch. The LT1203/LT1205
have a very wide bandwidth yet are tolerant of power
supply bypassing. The power supplies should be by-
passedwitha0.1µFor0.01µFceramiccapacitorwithin0.5
inch of the part.
LT1203 Channel-to-Channel Switching Transient
OUTPUT
50mV/DIV
INPUT
20mV/DIV
Circuit Layout
LOGIC
(PIN 5)
Use a ground plane to ensure a low impedance ground is
available throughout the PCB layout. Separate the inputs
LT1203/05 • AI01
RS = 50Ω
7
LT1203/LT1205
O U
W
U
PPLICATI
A
S I FOR ATIO
CMOS MUX Channel-to-Channel Switching Transient
only 10mVP-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.
OUTPUT
1V/DIV
Pixel Switching
INPUT
1V/DIV
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.
TodemonstratetheswitchingspeedoftheLT1203/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 75Ω cable. In Figure 2b, the
LT1203 switches to an input at zero at the end of the first
pixel and removes the following pixels.
LOGIC
CONTROL
LT1203/05 • AI02
RS = 50Ω
NOTE: 50 TIMES LARGER THAN LT1203 TRANSIENT
LT1203 Switching Inputs
LOGIC
(PIN 5)
OUTPUT
(PIN 7)
LT1203/05 • AI03
CHANNEL 1 = 0V
CHANNEL 2 = 2MHz SINEWAVE
J8
ENABLE
+
–
V
V
GND
J7
LOGIC
C4
4.7µF
+
+
R11
1.5k
R10
1.5k
C3
4.7µF
16
J1
R16
1
–
+
RED 1
75Ω
1
16
15
14
13
12
11
10
9
15
14
13
J9
RED
+1
+1
+1
+1
R
G
2
3
4
2
3
4
5
6
7
8
J2
R1
75Ω
RED 2
R7*
10k
R12
1.5k
J3
R2
75Ω
R17
75Ω
–
+
LT1205
GREEN 1
12
11
J10
GREEN
5
6
7
J4
R3
75Ω
GREEN 2
R8*
10k
R13
1.5k
R4
75Ω
R18
75Ω
+
–
C2
0.1µF
10
9
R14
1.5k
J11
BLUE
J5
BLUE 1
B
8
1
2
3
4
8
7
6
5
+1
+1
R15
1.5k
J6
BLUE 2
R5
75Ω
LT1203
LT1260
R9*
10k
R6
75Ω
LT1203/05 • F01
*OPTIONAL
C1
0.1µF
Figure 1. RGB MUX
8
LT1203/LT1205
O U
W
U
PPLICATI
A
S I FOR ATIO
4
3
V
= ±15V
S
L
F
R
= 150Ω
R = R = 1.3k
G
2
1
WORKSTATION
OUTPUT
R, B
0
G
–1
–2
–3
–4
RGB MUX
OUTPUT
1
10
100
1000
FREQUENCY (MHz)
LT1203/05 • F02a
LT1203/05 • F04
Figure 2a. Workstation and RGB MUX Output
Figure 4. RGB MUX Frequency Response of
Demonstration Board #041
Input Expansion
WORKSTATION
OUTPUT
The output impedance of the LT1203/LT1205 is typically
20Ω when enabled and 10MΩ when disabled or not
selected. This high disabled output impedance allows the
output of many LT1205s to be shorted together to form
large crosspoint arrays. With their outputs shorted to-
gether, shoot-through current is low because the “on”
channel is disabled before the “off” channel is activated.
RGB MUX
OUTPUT
Timing and Supply Current Waveforms
LT1203/05 • F02b
Figure 2b. RGB MUX Output Switched to Ground
After One Pixel
ENABLE
5V/DIV
IC #1
ENABLE
IC #2
5V/DIV
Demonstration Board
VOUT
1V/DIV
A Demonstration Board (#041) of the RGB MUX in Figure
1
has been fabricated and its layout is shown in Figure 3.
The small-signal bandwidth of the RGB MUX is set by the
bandwidth of the LT1260. The stray capacitance of the
surface mount feedback resistors RF and RG restricts the
–3dB bandwidth to about 95MHz. The bandwidth can be
improved by about 20% using the through-hole LT1260
and components. A frequency response plot in Figure 4
shows that the R, G, and B amplifiers have slightly
different frequency responses. The difference in the G
amplifier is due to different output trace routing to
feedback resistor R13.
IS
10mA/DIV
LT1203/05 • AI04
Four LT1205s are used in Figure 5 to form a 16-to-1
multiplexer which is very space efficient and uses only six
SOpackages. Inthisapplication15switchesareturnedoff
and only one is active. An attenuator is formed by the 15
deselected switches and the active device which has an
9
LT1203/LT1205
041A
R1
–
+
V
V
GND
LOGIC
ENABLE
R1
R
R2
R2
R10 C3
U3
R11
U1
U2
R7
R12
R3
R16
G
B
R17
R13
R14
G1
G2
C1
C2
R18
R8
C4
R15
R9
R4
B1
R5
(408) 432-1900
LT1203/LT1205 FAST SWITCHING
RGB MULTIPLEXER DEMO BOARD
B2
R6
COPYWRITE '93
MADE IN USA
LT1205/03 • F03
Figure 3. Demo Board #041 Layout
10
LT1203/LT1205
O U
W
U
PPLICATI
A
S I FOR ATIO
–15V
15V
GND
5V
C7
0.1µF
C1
0.1µF
A
16
8
B
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
15
14
13
12
11
10
9
1
2
3
CH0
+1
+1
+1
+1
Y0
A
C2
0.1µF
R1
75Ω
C
Y1
Y2
Y3
Y4
Y5
Y6
Y7
B
C
D
U5
74HCT238
EN
6
G1
5
4
G2B
G2A
7
U1
LT1205
OPTIONAL
X
10k
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
R
+1
+1
+1
+1
+
+
C5
2
3
7
R
S
+
4.7µF
75Ω
U6
LT1252
6
OUTPUT
U2
LT1205
–
4
R
1.6k
F
C6
4.7µF
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
+1
+1
+1
+1
R
G
1.6k
TRUTH TABLE
LOGIC
SELECT
OUTPUT
ENABLE
EN
D
X
L
L
L
L
L
L
L
C
X
L
L
L
B
X
L
A
X
L
H
L
H
L
H
L
H
L
H
L
H
L
H
L
U3
LT1205
L
OFF
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
L
H
H
L
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
L
+1
+1
+1
+1
H
H
H
H
L
L
L
L
H
H
H
H
L
H
H
L
L
H
H
H
H
H
H
H
H
CH8
CH9
L
H
H
L
L
H
H
CH10
CH11
CH12
CH13
CH14
CH15
CH15
R16
75Ω
U4
LT1205
C3
0.1µF
C4
0.1µF
H
LT1203/05 • F05
Figure 5. 16-to-1 Multiplexer and Truth Table
11
LT1203/LT1205
O U
W
U
PPLICATI
A
S I FOR ATIO
16-to-1 MUX Response
output impedance of only 25Ω at 10MHz. This attenuator
is responsible for the outstanding All Hostile Crosstalk
Rejection of 90dB at 10MHz with 15 input signals.
V
R
R
= ±15V
S
L
F
2
0
= 100Ω
= R = 1.6k
G
Several suggestions to attain this high rejection include:
1. Mount the feedback resistors for the surface mount
LT1252 on the back side of the PC board.
–2
–4
–6
2. Keepthefeedbacktrace(pin3)oftheLT1252asshort
as possible.
3. Route V+ and V– for the LT1205s on the component
(top) side and under the devices (between inputs and
outputs).
1
10
FREQUENCY (MHz)
100
LT1203/05 • AI07
4. Use the backside of the PC board as a solid ground
plane. Connect the LT1205 device grounds and by-
pass capacitors grounds as vias to the backside
ground plane.
Each “off” switch has 2.8pF of output capacitance and 15
“off” switches tied together represent a 48pF load to the
one active switch. In this case the active device will peak
about 3dB at 50MHz. An attribute of current feedback
amplifiers is that the bandwidth can easily be adjusted by
changing the feedback resistors, and in this application
the LT1252’s bandwidth is reduced to about 60MHz using
1.6kfeedbackresistors. Thishastheeffectofreducingthe
peaking in the MUX to 0.25dB and flattening the response
to 0.05dB at 30MHz.
16-to-1 MUX, Switching LT1205 Enable Lines
5V
SELECT
LINE C
0V
1V
4 × 4 Crosspoint
The compact high performance 4 × 4 crosspoint shown in
Figure 6 uses four LT1205s to route any input to any or all
outputs. The complete crosspoint uses only six SO pack-
ages and less than six square inches of PC board space.
The LT1254 quad current feedback amplifier serves as a
cabledriverwithagainof2.A±5Vsupplyisusedtoensure
that the maximum 150°C junction temperature of the
LT1254 is not exceeded in the SO package. With this
supply voltage the crosspoint can operate at a 70°C
ambient temperature and drive 2V (peak or DC) into a
double-terminated 75Ω video cable. The feedback resis-
tors of these output amplifiers have been optimized for
thissupplyvoltage.The –3dBbandwidthofthecrosspoint
is over 100MHz with only 0.8dB of peaking. All Hostile
Crosstalk Rejection is 85dB at 10MHz when a shorted
input is routed to all outputs. To obtain this level of
performanceitisnecessarytofollowtechniquessimilarto
0V
LT1203/05 • AI05
VIN4 = 0V
VIN0 = 1V
RF = RG = 1.6k
L = 100Ω
R
16-to-1 Multiplexer All Hostile Crosstalk Rejection
–20
V
R
R
= ±15V
= 10Ω
= 100Ω
S
S
L
–40
–60
–80
–100
–120
1
10
100
FREQUENCY (MHz)
LT1203/05 • AI06
12
LT1203/LT1205
O U
S
W
U
PPLICATI
A
I FOR ATIO
–5V
5V
GND
OUTPUT 0
3
2
R17
J5
+
75Ω
1
U6 A
LT1254
C1
0.1µF
CH0
J1
–
C2
0.1µF
1
2
3
4
5
6
7
8
16
R9
820Ω
+1
+1
+1
+1
15
14
13
12
11
10
9
R1
75Ω
R5
10k
R10
820Ω
OUTPUT 1
J6
5
R18
75Ω
+
U1
LT1205
7
U6 B
LT1254
6
–
R6
R11
820Ω
10k
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
+1
+1
+1
+1
R12
820Ω
C5
4.7µF
+
CH1
J2
OUTPUT 2
J7
10
4
R19
75Ω
+
8
U6 C
LT1254
R2
75Ω
U2
LT1205
9
–
11
CH2
J3
R13
820Ω
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
U5
74HC04
+1
+1
+1
+1
C6
4.7µF
R3
75Ω
R7
10k
R14
820Ω
+
OUTPUT 3
12
R20
75Ω
+
J8
14
U6 D
LT1254
U3
LT1205
13
–
R15
820Ω
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
+1
+1
+1
+1
R8
10k
R16
820Ω
TRUTH TABLE
SELECT LOGIC
INPUT
CH3
J4
CHANNEL
A
L
L
H
H
B
L
H
L
CH0
CH1
CH2
CH3
R4
75Ω
U4
LT1205
H
C3
0.1µF
C4
0.1µF
LT1203/05 • F06
A
B
A
B
A
B
A
B
SELECT LOGIC SELECT LOGIC SELECT LOGIC SELECT LOGIC
OUTPUT 0 OUTPUT 1 OUTPUT 2 OUTPUT 3
Figure 6. 4 × 4 Crosspoint and Truth Table
13
LT1203/LT1205
O U
W
U
PPLICATI
A
S I FOR ATIO
Output 3, the 4th pair of logic inputs labeled Select Logic
Output 3 is coded A = Low and B = High. To route
Channel 3 Input to all outputs, set all eight logic inputs
High. Channel 3 is the default input with all logic inputs
open. To shut off all channels a pair of LT1259s can be
substituted for the LT1254. The LT1259 is a dual current
feedback amplifier with a shutdown pin that reduces the
supply current to 0µA.
those used in the 16-to-1 crosspoint with one additional
suggestion:SurroundtheLT1205outputtracesbyground
plane and route them away from the (–) inputs of the
other three LT1254s.
Each pair of logic inputs labeled Select Logic Output is
used to select a particular output. The truth table is used
to select the desired input and is applied to each pair of
logic inputs. For example, to route Channel 1 Input to
Response of All Four Inputs for the 4 × 4 Crosspoint
4 × 4 Crosspoint, All Hostile Rejection
2
V
= ±5V
S
–40
–60
0
–2
–4
–80
–100
–120
–6
–8
V
R
R
= ±5V
S
F
L
= R = 820Ω
G
= 100Ω
1
10
FREQUENCY (MHz)
100 200
1
10
100
FREQUENCY (MHz)
LT1203/05 • AI08
LT1203/05 • AI09
4 × 4 Crosspoint, Switching Channel 0 to Channel 2
5V
INPUT A
OF SELECT
LOGIC
OUTPUT 0
0V
LT1203/05 • AI10
CHANNEL 0 = 1V
CHANNEL 2 = 0V
14
LT1203/LT1205
W
W
SI PLIFIED SCHE ATIC
+
V
2V
–
V
–
+
V
V
OFF
IN 0
IN 1
OUT
ENABLE
LOGIC
LOGIC
+
V
–2V
–
GND
V
LT1203/05 • SS
U
PACKAGE DESCRIPTIO
Dimensions in inches (millimeters) unless otherwise noted.
N8 Package
8-Lead Plastic DIP
0.400
(10.160)
MAX
8
7
6
5
4
0.250 ± 0.010
(6.350 ± 0.254)
1
2
3
0.130 ± 0.005
0.300 – 0.320
0.045 – 0.065
(3.302 ± 0.127)
(1.143 – 1.651)
(7.620 – 8.128)
0.065
(1.651)
TYP
0.009 – 0.015
(0.229 – 0.381)
0.125
0.020
(0.508)
MIN
(3.175)
MIN
+0.025
0.045 ± 0.015
(1.143 ± 0.381)
0.325
–0.015
+0.635
8.255
(
)
–0.381
0.100 ± 0.010
(2.540 ± 0.254)
0.018 ± 0.003
(0.457 ± 0.076)
N8 0392
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
15
LT1203/LT1205
U
PACKAGE DESCRIPTIO
Dimensions in inches (millimeters) unless otherwise noted.
S8 Package
8-Lead Plastic SOIC
0.189 – 0.197*
(4.801 – 5.004)
7
5
8
6
0.150 – 0.157*
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
1
3
4
2
0.010 – 0.020
(0.254 – 0.508)
× 45°
0.053 – 0.069
(1.346 – 1.752)
0.004 – 0.010
(0.101 – 0.254)
0.008 – 0.010
(0.203 – 0.254)
0°– 8° TYP
0.016 – 0.050
0.406 – 1.270
0.050
(1.270)
BSC
0.014 – 0.019
(0.355 – 0.483)
SO8 0294
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006 INCH (0.15mm).
S Package
16-Lead Plastic SOIC
0.386 – 0.394*
(9.804 – 10.008)
16
15
14
13
12
11
10
9
0.150 – 0.157*
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
5
7
8
1
2
3
4
6
0.010 – 0.020
(0.254 – 0.508)
× 45°
0.053 – 0.069
(1.346 – 1.752)
0.004 – 0.010
(0.101 – 0.254)
0.008 – 0.010
(0.203 – 0.254)
0° – 8° TYP
0.050
(1.270)
TYP
0.014 – 0.019
(0.355 – 0.483)
0.016 – 0.050
0.406 – 1.270
SO16 0893
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006 INCH (0.15mm).
LT/GP 0494 10K • PRINTED IN USA
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7487
16
●
●
LINEAR TECHNOLOGY CORPORATION 1994
(408) 432-1900 FAX: (408) 434-0507 TELEX: 499-3977
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