LT1675/LT1675-1
250MHz, Triple and Single
RGB Multiplexer with Current Feedback Amplifiers
configured for a fixed gain of 2, eliminating six external
FEATURES
s
s
s
s
s
s
s
s
s
s
100MHz Pixel Switching
– 3dB Bandwidth: 250MHz
Small 16-Pin SSOP Package
Channel Switching Time: 2.5ns
Expandable to Larger Arrays
Drives Cables Directly
High Slew Rate: 1100V/µs
Low Switching Transient: 50mV
Shutdown Supply Current: 0mA
Output Short-Circuit Protected
gain setting resistors. The SPDT switches are designed to
be break-before-make to minimize unwanted signals cou-
pling to the input.
The LT1675-1 is a single version with two inputs, a single
output and is ideal for a single channel application such as
video sync.
APPLICATIONS
s
s
s
s
s
RGB Switching
Workstation Graphics
Pixel Switching
Coaxial Cable Drivers
High Speed Signal Processing
DESCRIPTION
The LT
®
1675 is a high speed RGB multiplexer designed for
pixel switching and fast workstation graphics.
Included on chip are three SPDT switches and three
current feedback amplifiers. The current feedback ampli-
fiers drive double-terminated 50Ω or 75Ω cables and are
The key to the LT1675 fast switching speed is Linear
Technology’s proprietary high speed bipolar process. This
MUX can toggle between sources in excess of 100MHz,
has a slew rate over 1000V/µs and has a –3dB bandwidth
of 250MHz. The speed and ease of use of the LT1675 make
it ideal for high performance PCs, workstations and pro-
fessional video monitors. The input-referred switching
transient is only 50mV
P-P
and lasts just 5ns, making it
virtually undetectable. Power supply requirements are
±4V
to
±6V
and power dissipation is only 300mW on
±5V,
or 100mW for the LT1675-1. The expandable feature uses
the disable pin to reduce the power dissipation to near
0mW in the off parts.
Unlike competitive solutions that are in bulky high pin
count packages, the LT1675 is in a 16-lead narrow body
SSOP. This small footprint, the size of an SO-8, results in
a very clean high performance solution. The LT1675-1 is
available in the tiny MSOP and the SO-8.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATION
High Speed RGB MUX
LT1675
RED 1
75Ω
+2
GREEN 1
75Ω
75Ω
BLUE 1
75Ω
RED 2
75Ω
GREEN 2
75Ω
SELECT RGB1/RGB2
BLUE 2
75Ω
+1
ENABLE
1675 TA01
+1
+1
CABLE
+1
+2
+1
+2
+1
U
U
U
Select Pin Switches Inputs at 100MHz
V
+
75Ω CABLE
V
OUT RED
75Ω
SELECT
LOGIC
PIN 10
0V
1V
RED
OUT
0V
500mV/DIV
3V
1V/DIV
V
OUT GREEN
75Ω
75Ω CABLE
V
OUT BLUE
75Ω
V
–
RED 1 = 0V, RED 2 = 1V, R
L
= 100Ω
MEASURED BETWEEN 50Ω BACK TERMINATION AND 50Ω LOAD
1675 TA02
1
LT1675/LT1675-1
ABSOLUTE
MAXIMUM
RATINGS
Supply Voltage .....................................................
±6.3V
Inputs, ENABLE and SELECT, Current ................
±20mA
Output Short-Circuit Duration (Note 2) ......... Continuous
Specified Temperature Range (Note 3) ....... 0°C to 70°C
PACKAGE/ORDER INFORMATION
TOP VIEW
V
IN1
GND
V
IN2
V
–
1
2
3
4
8
7
6
5
V
+
ENABLE
V
OUT
SELECT
V
IN1
1
GND 2
V
IN2
3
V
–
4
TOP VIEW
8
7
6
5
V
+
ENABLE
V
OUT
SELECT
MS8 PACKAGE
8-LEAD PLASTIC MSOP
T
JMAX
= 150°C,
θ
JA
= 250°C/ W
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 150°C,
θ
JA
= 150°C/ W
ORDER PART
NUMBER
LT1675CMS8-1
MS8 PART
MARKING
LTGX
ORDER PART
NUMBER
LT1675CS8-1
Consult factory for Industrial and Military grade parts.
2
U
U
W
W W
U
W
(Note 1)
Operating Temperature Range ................ – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 150°C
Junction Temperature (Note 4) ............................ 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
TOP VIEW
RED 1
GREEN 1
BLUE 1
GND
GND
RED 2
GREEN 2
BLUE 2
1
2
3
4
5
6
7
8
16 V
+
15 V
OUT RED
14 V
OUT GREEN
13 V
OUT BLUE
12 V
–
11 V
–
10 SELECT
9
ENABLE
GN PACKAGE
16-LEAD PLASTIC SSOP NARROW
T
JMAX
= 150°C,
θ
JA
= 120°C/ W
S8 PART
MARKING
16751
ORDER PART
NUMBER
LT1675CGN
GN PART
MARKING
1675
LT1675/LT1675-1
ELECTRICAL CHARACTERISTICS
PARAMETER
Output Offset Voltage
Output Offset Matching
Input Current
Input Resistance
PSRR
DC Gain Error 0V to 1V
CONDITIONS
Any Input Selected
0°C
≤
T
A
≤
70°C, V
S
=
±5V,
R
L
=
∞
,
V
IN
= 0V LT1675 (Pins 1, 2, 3, 6, 7, 8),
LT1675-1 (Pins 1, 3), ENABLE = 0V, unless otherwise specified.
MIN
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
TYP
20
5
– 12
MAX
40
20
– 30
UNITS
mV
mV
µA
kΩ
dB
Between Outputs R1 to R2, G1 to G2, B1 to B2
Any Input Selected
V
IN
=
±1V
V
S
=±2.6V to
±6V,
Measured at Output
V
IN
= 1V, R
L
=
∞
V
IN
= 1V, R
L
= 150Ω
V
IN
= 1V, R
L
= 75Ω
V
IN
= –1V, R
L
=
∞
V
IN
= –1V, R
L
= 150Ω
V
IN
= –1V, R
L
= 75Ω
V
IN
= 2V, R
L
=
∞
V
IN
= 2V, R
L
= 150Ω
V
IN
= 2V, R
L
= 75Ω
V
IN
= – 2V, R
L
=
∞
V
IN
= – 2V, R
L
= 150Ω
V
IN
= – 2V, R
L
= 75Ω
100
38
700
50
3
4
5
3
4
8
6
8
10
6
8
20
%
%
%
%
%
%
V
V
V
V
V
V
DC Gain Error 0V to –1V
Output Voltage
3.1
2.8
2.4
– 3.1
– 2.7
– 2.3
1.1
50
25
8
3.4
3.0
2.8
– 3.3
– 3.0
– 2.6
1.5
70
33
1
11
0.3
450
150
90
30
42
100
14
33
600
200
180
60
0.8
2.0
Disabled Output Impedance
Maximum Output Current
Supply Current
LT1675
LT1675-1
ENABLE Pin Current
SELECT Pin Current
SELECT Low
SELECT High
LT1675
LT1675-1
LT1675
LT1675-1
ENABLE Open
V
IN
=
±1V,
V
O
= 0V
ENABLE = 0V
ENABLE = 4.7V
ENABLE = 0V
ENABLE = 4.7V
ENABLE= 0V
ENABLE= 0V
SELECT = 0V
SELECT = 0V
SELECT (See Truth Table)
SELECT (See Truth Table)
kΩ
mA
mA
µA
mA
µA
µA
µA
µA
µA
V
V
2
3
LT1675/LT1675-1
AC CHARACTERISTICS
PARAMETER
Slew Rate
Full Power Bandwidth (Note 5)
Small-Signal –3dB Bandwidth
Gain Flatness
Gain Matching
Channel-to-Channel Select Time
Delay Time
Switching Time
Enable Time
Disable Time
Input Pin Capacitance
SELECT Pin Capacitance
ENABLE Pin Capacitance
LT1675
LT1675-1
LT1675
LT1675-1
Output Pin Capacitance (Disabled)
Small-Signal Rise Time
Propagation Delay
Overshoot
On-Channel to Off-Channel Crosstalk
Chip Disable Crosstalk
Channel Select Output Transient
Differential Gain (Note 6)
Differential Phase (Note 6)
0°C
≤
T
A
≤
70°C, V
S
=
±5V,
R
L
= 150Ω
,
V
IN
= 0V LT1675 (Pins 1, 2, 3, 6, 7, 8),
LT1675-1 (Pins 1, 3), ENABLE = 0V, unless otherwise specified.
CONDITIONS
V
OUT
= 5V
P-P
V
OUT
=6V
P-P
Less Than 1dB Peaking
Less Than 0.1dB
R to G to B
R1 to R2, G1 to G2, B1 to B2, LT1675-1 V
IN1
to V
IN2
R1 = 0V, R2 = 1V
Measured from Time SELECT Pin Crosses Logic Threshold
Time for V
OUT
to Go from 0V to 1V
MIN
TYP
1100
58
250
70
0.10
0.01
5.0
2.5
10
100
2
2.2
1.5
2.1
1.5
ENABLE Open
V
IN
= 300mV
P-P
, R
L
= 100Ω
V
IN
= 300mV
P-P
, R
L
= 100Ω
V
IN
= 300mV
P-P
, R
L
= 100Ω
Measured at 10MHz
Measured at 10MHz, ENABLE Open
Measured Between Back Termination and Load
4.4
1.85
3
10
60
90
50
0.07
0.05
MAX
UNITS
V/µs
MHz
MHz
MHz
dB
dB
ns
ns
ns
ns
pF
pF
pF
pF
pF
pF
ns
ns
%
dB
dB
mV
P-P
%
DEG
The
q
denotes specifications that apply over the specified temperature
range.
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
May require a heat sink.
Note 3:
The LT1675/LT1675-1 are guaranteed to meet specified
performance from 0°C to 70°C and are designed, characterized and
expected to meet these extended temperature limits, but are not tested at
– 40°C and 85°C. Guaranteed I grade parts are available; consult factory.
Note 4:
T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formula:
LT1675CGN: T
J
= T
A
+ (P
D
)(120°C/W)
LT1675CMS8-1: T
J
= T
A
+ (P
D
)(250°C/W)
LT1675CS8-1: T
J
= T
A
+ (P
D
)(150°C/W)
Note 5:
Full power bandwidth is calculated from the slew rate
measurement:
FPBW = SR/2πV
PEAK
.
Note 6:
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°. Nine
identical MUXs were cascaded giving an effective resolution of 0.011%
and 0.011°.
LT1675
LT1675-1
BLUE OUT
BLUE 1
BLUE 2
OFF
VOUT
VIN1
VIN2
OFF
Truth Table
SELECT
1
0
X
ENABLE
0
0
1
RED OUT
RED 1
RED 2
OFF
GREEN OUT
GREEN 1
GREEN 2
OFF
4
LT1675/LT1675-1
TYPICAL PERFORMANCE CHARACTERISTICS
Gain and Phase vs
Frequency
5
4
3
2
GAIN (dB)
1
0
–1
–2
–3
–4
C
L
= 0pF
R
L
= 150Ω
1M
10M
100M
FREQUENCY (Hz)
GAIN
PHASE
0
–20
–40
–60
PHASE (DEG)
GAIN (dB)
C
L
= 3pF
–100
–120
–140
–160
–180
–200
1G
1675 G01
1
0
–1
–2
–3
–4
100k
1M
10M
100M
FREQUENCY (Hz)
1G
1675 G02
GAIN (dB)
–5
100k
– 3dB Bandwidth vs
Supply Voltage
300
280
260
R
L
= 150Ω
CROSSTALK REJECTION (dB)
CROSSTALK REJECTION (dB)
FREQUENCY (MHz)
240
220
200
180
160
140
120
100
2
4
5
3
SUPPLY VOLTAGE (±V)
6
1675 G04
Crosstalk Rejection vs Frequency
(Disabled)
–10
70
POWER SUPPLY REJECTION RATIO (dB)
–20
CROSSTALK REJECTION (dB)
–30
–40
–50
–60
–70
–80
–90
–100
R
S
= 75Ω
R
L
= 150Ω
40
30
20
10
0
–10
–20
–30
100k
1M
–PSRR
OUTPUT VOLTAGE (V
P-P
)
–110
100k
1M
10M
100M
FREQUENCY (Hz)
U W
1675 G06
Frequency Response with
Capacitive Loads
6
5
4
3
2
R
L
= 150Ω
C
L
= 10pF
C
L
= 5pF
6.5
6.4
6.3
6.2
6.1
6.0
5.9
5.8
5.7
5.6
Gain vs Frequency
R
L
= 100Ω
–80
C
L
= 0pF
R G
B
5.5
10k
100k
1M
10M
FREQUENCY (Hz)
100M
1675 G03
Crosstalk Rejection vs Frequency
–30
–40
–50
–60
–70
–80
–90
–100
–110
–120
–130
100k
1M
10M
100M
FREQUENCY (Hz)
1G
1675 G05
Crosstalk Rejection vs Frequency
20
10
0
–10
–20
–30
–40
–50
–60
–70
–80
100k
1M
10M
100M
FREQUENCY (Hz)
1G
1675 G23
R
S
= 75Ω
R
L
= 150Ω
R1 DRIVEN
R2 SELECTED
R
S
= 75Ω
R
L
= 150Ω
G1 DRIVEN
R1 SELECTED
Power Supply Rejection Ratio
vs Frequency
60
50
+PSRR
V
S
=
±5V
T
A
= 25°C
R
L
= 150Ω
8
7
6
5
4
3
2
Undistorted Output Swing
vs Frequency
V
S
=
±5V
R
L
= 150Ω
1G
10M
100M
FREQUENCY (Hz)
1G
1675 G07
1M
10M
100M
FREQUENCY (Hz)
1G
1675 G08
5
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
