LT6555
1
6555f
APPLICATIO S
U
DESCRIPTIO
U
FEATURES
TYPICAL APPLICATIO
U
The LT
6555 is a high speed triple 2:1 video multiplexer
with an internally fixed gain of 2. The individual amplifiers
are optimized for performance with a double terminated
75
video load and feature a 3dB 2V
P-P
bandwidth of
450MHz, making them ideal for driving very high resolu-
tion video signals. Separate power supply pins for each
amplifier boost channel separation to 72dB, allowing the
LT6555 to excel in many high speed applications.
While the performance of the LT6555 is optimized for dual
supply operation, it can also be operated with a single
supply as low as 4.5V. Using dual 5V supplies, each
amplifier draws only 9mA. When disabled, the amplifiers
draw less than 500
A and the outputs become high
impedance.
The LT6555 is manufactured on Linear Technology's
proprietary low voltage complementary bipolar process
and is available in 24-lead SSOP and ultra-compact
24-lead QFN packages.
RGB Amplifiers
UXGA Video Multiplexing
LCD Projectors
650MHz 3dB Small Signal Bandwidth
450MHz 3dB 2V
P-P
Large-Signal Bandwidth
120MHz
0.1dB Bandwidth
High Slew Rate: 2200V/
s
Fixed Gain of 2; No External Resistors Required
72dB Channel Separation at 10MHz
50dB Channel Separation at 100MHz
80dBc 2nd Harmonic Distortion at 10MHz, 2V
P-P
70dBc 3rd Harmonic Distortion at 10MHz, 2V
P-P
Low Supply Current: 9mA per Amplifier
6.5ns 0.1% Settling Time for 2V Step
I
SS
500A per Amplifier when Disabled
Differential Gain of 0.033%, Differential
Phase of 0.022
Wide Supply Range:
2.25V (4.5V) to 6V (12V)
Available in 24-Lead SSOP and 24-Lead QFN
Packages
650MHz Gain of 2 Triple
2:1Video Multiplexer
RGB Multiplexer and Line Driver
Video Amplitude Transient Response
LT6555
V
+
V
R
INA
G
INA
B
INA
R
INB
G
INB
B
INB
75
75
75
75
75
75
SELECT A/B
6555 TA01a
AGND
ENABLE
DGND
75
75
R
OUT
75
75
G
OUT
75
75
B
OUT
2
2
2
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TIME (ns)
0
OUTPUT (V)
0.6
1.0
1.4
1.8
1.6
16
6555 G21
0.2
0.2
0.4
0.8
1.2
0
0.4
4
8
12
2
18
6
10
14
20
V
IN
= 0V TO 700mV
V
S
=
5V
R
L
= 150
T
A
= 25
C
LT6555
2
6555f
Total Supply Voltage (V
+
to V
) ............................ 12.6V
Input Current (Note 2) ........................................
10mA
Output Current (Continuous) .............................
70mA
EN to DGND Voltage (Note 2) ................................. 5.5V
SEL to DGND Voltage (Note 2) .................................. 8V
Output Short-Circuit Duration (Note 3) ............ Indefinite
Operating Temperature Range (Note 4) ... 40
C to 85C
Specified Temperature Range (Note 5) .... 40
C to 85C
ORDER PART
NUMBER
T
JMAX
= 150
C,
JA
= 90
C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
LT6555CGN
LT6555IGN
ABSOLUTE AXI U
RATI GS
W
W
W
U
PACKAGE/ORDER I FOR ATIO
U
U
W
(Note 1)
Junction Temperature
SSOP ................................................................ 150
C
QFN .................................................................. 125
C
Storage Temperature Range
SSOP ................................................. 65
C to 150C
QFN ................................................... 65
C to 125C
Lead Temperature (Soldering, 10 sec)
SSOP ................................................................ 300
C
1
2
3
4
5
6
7
8
9
10
11
12
TOP VIEW
GN PACKAGE
24-LEAD PLASTIC SSOP
24
23
22
21
20
19
18
17
16
15
14
13
IN1A
DGND
IN2A
V
REF
IN3A
AGND1
IN1B
AGND2
IN2B
AGND3
IN3B
V
V
+
EN
SEL A/B
V
+
OUT1
V
OUT2
V
+
OUT3
V
V
+
V
+
G = +2
G = +2
G = +2
ORDER PART
NUMBER
UF PART*
MARKING
6555
LT6555CUF
LT6555IUF
24 23 22 21 20 19
7
8
9
TOP VIEW
25
UF PACKAGE
24-LEAD (4mm
4mm) PLASTIC QFN
10 11 12
6
5
4
3
2
1
13
14
15
16
17
18
V
REF
IN3A
AGND1
V
IN1B
AGND2
V
+
OUT1
V
OUT2
V
+
OUT3
IN2A
DGND
IN1A
V
+
EN
SEL A/B
IN2B
AGND3
IN3B
V
+
V
+
V
T
JMAX
= 125
C,
JA
= 37
C/W,
JC
= 2.6
C/W
EXPOSED PAD (PIN 25) IS V
MUST BE SOLDERED TO PCB
ELECTRICAL CHARACTERISTICS
The
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
C. V
S
=
5V, R
L
= 150
, C
L
= 1.5pF, V
EN
= 0.4V, V
AGND
, V
DGND
, V
VREF
= 0V.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
OS
Input Referred Offset Voltage
V
IN
= 0V, V
OS
= V
OUT
/2
5
16
mV
24
mV
I
IN
Input Current
17
45
A
R
IN
Input Resistance
V
IN
=
1V
100
400
k
C
IN
Input Capacitance
f = 100kHz
1
pF
PSRR
Power Supply Rejection Ratio
V
S
=
2.25V to 6V (Note 6)
56
62
dB
I
PSRR
Input Current Power Supply Rejection
V
S
=
2.25V to 6V (Note 6)
1
4
A/V
A
V
ERR
Gain Error
V
OUT
=
2V, Nominal Gain 2V/V
2.5
%
A
V
MATCH
Gain Matching
Any One Channel to Another
0.33
%
V
OUT
Output Voltage Swing
(Note 7)
3.15
3.4
V
3.0
V
LT6555
3
6555f
I
S
Supply Current, Per Amplifier
R
L
=
9
12
mA
14
mA
Supply Current, Disabled, Per Amplifier
V
EN
= 4V, R
L
=
47
500
A
V
EN
= Open, R
L
=
42
500
A
I
EN
Enable Pin Current
V
EN
= 0.4V
200
95
A
V
EN
= 4V
75
21
A
I
SEL
Select Pin Current
V
SEL
= 0.4V
50
5
A
V
SEL
= 4V
50
1
A
I
SC
Output Short-Circuit Current
R
L
= 0
, V
IN
=
1V
50
105
mA
SR
Slew Rate
1V on 2.5V Output Step (Note 8)
1600
2200
V/
s
3dB BW
Small-Signal 3dB Bandwidth
V
OUT
= 200mV
P-P
650
MHz
0.1dB BW
Gain Flatness
0.1dB Bandwidth
V
OUT
= 200mV
P-P
120
MHz
FPBW
Full Power Bandwidth 2V
V
OUT
= 2V
P-P
(Note 9)
250
350
MHz
Full Power Bandwidth 4V
V
OUT
= 4V
P-P
(Note 9)
175
MHz
All-Hostile Crosstalk
f = 10MHz, V
IN
= 1V
P-P
72
dB
f = 100MHz, V
IN
= 1V
P-P
50
dB
Selected Channel to Unselected
f = 10MHz, V
IN
= 1V
P-P
80
dB
Channel Crosstalk
f = 100MHz, V
IN
= 1V
P-P
55
dB
Channel Select Output Transient
INA = INB = 0V
200
mV
P-P
Channel-to-Channel Select Time
INA = 1V, INB = 1V
8
ns
from 50% SEL to V
OUT
= 0V
t
S
Settling Time
0.1% of V
FINAL
, V
STEP
= 2V
6.5
ns
t
R
,
t
F
Small-Signal Rise and Fall Time
10% to 90%, V
OUT
= 400mV
P-P
520
ps
dG
Differential Gain
(Note 10)
0.033
%
dP
Differential Phase
(Note 10)
0.022
Deg
HD2
2nd Harmonic Distortion
f = 10MHz, V
OUT
= 2V
P-P
80
dBc
HD3
3rd Harmonic Distortion
f = 10MHz, V
OUT
= 2V
P-P
70
dBc
ELECTRICAL CHARACTERISTICS
The
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
C. V
S
=
5V, R
L
= 150
, C
L
= 1.5pF, V
EN
= 0.4V, V
AGND
, V
DGND
, V
VREF
= 0V.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: This parameter is guaranteed to meet specified performance
through design and characterization. It is not production tested.
Note 3: As long as output current and junction temperature are kept below
the Absolute Maximum Ratings, no damage to the part will occur.
Depending on the supply voltage, a heat sink may be required.
Note 4: The LT6555C is guaranteed functional over the operating
temperature range of 40
C to 85C.
Note 5: The LT6555C is guaranteed to meet specified performance from
0
C to 70C. The LT6555C is designed, characterized and expected to
meet specified performance from 40
C and 85C but is not tested or QA
sampled at these temperatures. The LT6555I is guaranteed to meet
specified performance from 40
C to 85C.
Note 6: In order to follow the constraints for 4.5V operation for PSRR
and I
PSRR
testing at
2.25V, the DGND pin is set to V
, the EN pin is set
to V
+ 0.4V, and the SEL pin is set to either V
+ 0.4V or V
+ 4V. At
6V
and all other cases, DGND is set to ground and the EN and SEL pins are
referenced from it.
Note 7: The V
REF
pin is set to 1V when testing positive swing and 1V
when testing negative swing to ensure that the internal input clamps do
not limit the output swing.
Note 8: Slew rate is 100% production tested using both inputs of
channel 2. Slew rates of channels 1 and 3 are guaranteed through
design and characterization.
Note 9: Full power bandwidth is calculated from the slew rate:
FPBW = SR/(
V
P-P
)
Note 10: Differential gain and phase are measured using a Tektronix
TSG120YC/NTSC signal generator and a Tektronix 1780R video
measurement set. The resolution of this equipment is better than 0.05%
and 0.05
. Nine identical amplifier stages were cascaded giving an
effective resolution of better than 0.0056% and 0.0056%.
LT6555
4
6555f
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
Output Voltage Swing
vs I
LOAD
(Output High)
Output Voltage Swing
vs I
LOAD
(Output Low)
Input Bias Current
vs Temperature
Maximum Output Voltage Swing
vs V
REF
Pin Voltage
EN Pin Current vs EN Pin Voltage
Input Referred Offset Voltage
vs Temperature
Supply Current per Amplifier
vs Temperature
Supply Current per Amplifier
vs Supply Voltage
Supply Current per Amplifier
vs EN Pin Voltage
TEMPERATURE (
C)
55
SUPPLY CURRENT (mA)
15
25
45
125
6555 G01
35
5
65
85 105
12
10
8
6
4
2
0
V
S
=
5V
R
L
=
V
IN
= 0V
V
EN
= 0V
V
EN
= 4V
V
EN
= 0.4V
TOTAL SUPPLY VOLTAGE (V)
0
4
6555 G02
1
2
3
5
6
7
8
9 10 11 12
SUPPLY CURRENT (mA)
12
10
8
6
4
2
0
V
EN
, V
IN
,
V
DGND
, V
SEL
= 0V
T
A
= 25
C
TEMPERATURE (
C)
55
15
OFFSET VOLTAGE (mV)
10
0
5
10
15
25
45
125
6555 G04
5
35
5
65
85 105
15
V
S
=
5V
V
IN
= 0V
TEMPERATURE (
C)
55
INPUT BIAS CURRENT (
A)
20
15
10
105
6555 G05
25
30
40
15
25
65
35
125
5
45
85
35
0
5
V
S
=
5V
V
IN
= 1.5V
V
IN
= 1.5V
V
IN
= 0V
EN PIN VOLTAGE (V)
0
EN PIN CURRENT (
A)
0
20
40
60
80
100
120
140
6555 G06
2
5
1
3
4
V
S
=
5V
V
DGND
= 0V
T
A
= 55
C
T
A
= 25
C
T
A
= 125
C
V
REF
PIN VOLTAGE (V)
2
OUTPUT VOLTAGE (V)
0
2
2
6555 G07
2
4
1
0
1
1.5
0.5
0.5
1.5
4
1
1
3
3
V
S
=
5V
R
L
= 150
HIGH SWING
LOW SWING
T
A
= 125
C
T
A
= 125
C
T
A
= 25
C
T
A
= 25
C
T
A
= 55
C
T
A
= 55
C
SOURCE CURRENT (mA)
0
OUTPUT VOLTAGE (V)
3
4
5
80
6555 G08
2
1
0
10 20 30 40 50 60 70
90 100
V
S
=
5V
V
IN
= 2V
V
VREF
= 0V
T
A
= 125
C
V
REF
INPUT
CLAMPING
T
A
= 25
C
T
A
= 55
C
SINK CURRENT (mA)
0
OUTPUT VOLTAGE (V)
2
1
0
80
6555 G09
3
4
5
10 20 30 40 50 60 70
90 100
V
S
=
5V
V
IN
= 2V
V
VREF
= 0V
T
A
= 125
C
V
REF
INPUT
CLAMPING
T
A
= 25
C
T
A
= 55
C
EN PIN VOLTAGE (V)
SUPPLY CURRENT (mA)
6555 G03
12
10
8
6
4
2
0
0
1.0
2.0
2.5
0.5
1.5
3.0
3.5
4.0
V
S
=
5V
R
L
=
V
IN
= 0V
T
A
= 55
C
T
A
= 125
C
T
A
= 25
C
LT6555
5
6555f
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
Frequency Response
vs Output Amplitude
Gain Flatness vs Frequency
Crosstalk vs Frequency
Frequency Response with
Capacitive Loads
Harmonic Distortion vs Frequency
Input Noise Spectral Density
Input Impedance vs Frequency
Input Referred PSRR
vs Frequency
FREQUENCY (kHz)
0.001
0.01
0.1
1
10
1
INPUT NOISE VOLTAGE (nV/
Hz OR pA/
Hz)
10
100
i
n
1000
100
6555 G10
V
S
=
5V
T
A
= 25
C
e
n
6555 G11
FREQUENCY (MHz)
INPUT IMPEDANCE (k
)
0.01
0.1
10
100
1000
1
1000
100
10
1
0.1
V
S
=
5V
V
IN
= 0V
T
A
= 25
C
FREQUENCY (MHz)
20
POWER SUPPLY REJECTION RATIO (dB)
40
70
10
30
50
60
0.001
0.1
1
10
100
6555 G12
0
0.01
PSRR
+PSRR
PSRR
V
S
=
5V
T
A
= 25
C
FREQUENCY (MHz)
2
GAIN (dB)
4
5
7
9
8
0.1
10
100
1000
6555 G13
0
1
6
3
1
V
S
=
5V
R
L
= 150
T
A
= 25
C
V
OUT
= 2V
P-P
V
OUT
= 4V
P-P
V
OUT
= 200mV
P-P
FREQUENCY (MHz)
6.00
NORMALIZED GAIN (dB)
6.10
6.20
5.95
6.05
6.15
0.1
10
100
1000
6555 G14
5.90
1
IN3A
IN1B
IN1A
IN2B
IN2A
IN3B
V
S
=
5V
V
OUT
= 200mV
P-P
R
L
= 150
T
A
= 25
C
FREQUENCY (MHz)
2
GAIN (dB)
2
6
10
14
0.1
10
100
1000
6555 G15
6
1
18
4
0
4
8
12
16
V
S
=
5V
V
OUT
= 2V
P-P
R
L
= 150
T
A
= 25
C
C
L
= 4.7pF
C
L
= 10pF
C
L
= 0pF
FREQUENCY (MHz)
80
AMPLITUDE (dB)
40
0
100
60
20
0.1
10
100
1000
6555 G16
120
1
V
S
=
5V
V
OUT
= 2V
P-P
R
L
= 150
T
A
= 25
C
WORST
ADJACENT
ALL
CHANNELS
DRIVEN
Crosstalk vs Frequency
FREQUENCY (MHz)
100
DISTORTION (dBc) 80
60
40
20
0.01
1
10
100
6555 G18
120
0.1
0
110
90
70
50
30
10
V
S
=
5V
V
OUT
= 2V
P-P
R
L
= 150
T
A
= 25
C
HD3
HD2
FREQUENCY (MHz)
80
AMPLITUDE (dB)
40
0
100
60
20
0.1
10
100
1000
6555 G17
120
1
V
S
=
5V
V
IN
= 1V
P-P
R
L
= 150
T
A
= 25
C
DRIVE IN A,
SELECT IN B
DRIVE IN B,
SELECT IN A
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