LT6556
750MHz Gain of 1 Triple
2:1Video Multiplexer
FEATURES
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DESCRIPTIO
750MHz –3dB Small Signal Bandwidth
450MHz –3dB 2V
P-P
Large-Signal Bandwidth
120MHz ±0.1dB Bandwidth
High Slew Rate: 2100V/µs
Fixed Gain of 1; No External Resistors Required
72dB Channel Separation at 10MHz
52dB Channel Separation at 100MHz
–84dBc 2nd Harmonic Distortion at 10MHz, 2V
P-P
–87dBc 3rd Harmonic Distortion at 10MHz, 2V
P-P
Low Supply Current: 9.5mA per Amplifier
6.5ns 0.1% Settling Time for 2V Step
I
SS
≤ 330µA 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
The LT
®
6556 is a high speed triple 2:1 video multiplexer
with an internally fixed gain of 1. The individual buffers
are optimized for performance with a 1k load and feature a
2V
P-P
–3dB bandwidth of 450MHz, making them ideal for
driving very high resolution video signals. Separate power
supply pins for each amplifier boost channel separation
to 72dB, allowing the LT6556 to excel in many high speed
applications.
While the performance of the LT6556 is optimized for dual
supply operation, it can also be operated with a single sup-
ply as low as 4.5V. Using dual 5V supplies, each amplifier
draws only 9.5mA. When disabled, the amplifiers draw
less than 330µA and the outputs become high impedance.
For applications requiring a fixed gain of 2, refer to the
LT6555 datasheet.
The LT6556 is available in 24-lead SSOP and ultra-compact
24-lead QFN packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
APPLICATIO S
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RGB Buffers
UXGA Video Multiplexing
LCD Projectors
TYPICAL APPLICATIO
R
INA
G
INA
B
INA
LT6556
75Ω
×1
RGB Multiplexer and Line Driver
V
+
Large-Signal Transient Response
1.5
R
OUT
1k
1.0
0.5
OUTPUT (V)
V
IN
= 2V
P-P
V
S
=
±5V
R
L
= 1k
T
A
= 25°C
75Ω
75Ω AGND
×1
1k
R
INB
G
INB
B
INB
G
OUT
0
–0.5
–1.0
75Ω
–1.5
75Ω
×1
SELECT A/B
V
REF
75Ω
ENABLE
DGND
V
–
6556 TA01
0
2
B
OUT
1k
U
4
6
8 10 12 14 16 18 20
TIME (ns)
6556 TA02
U
U
6556f
1
LT6556
ABSOLUTE
AXI U RATI GS
Total Supply Voltage (V
+
to V
–
) .............................12.6V
Input Current (Note 2) .........................................±10mA
Output Current (Continuous) ..............................±70mA
⎯
E
⎯
N 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 85°C
Specified Temperature Range (Note 5) .... –40°C to 85°C
PACKAGE/ORDER I FOR ATIO
TOP VIEW
IN1A
DGND
IN2A
V
REF
IN3A
AGND1
IN1B
AGND2
IN2B
1
2
3
4
5
6
7
8
9
G = +1
G = +1
G = +1
23 EN
22 SEL A/B
21 V
+
20 OUT1
19
V
–
V
REF
1
IN3A 2
AGND1 3
V
–
4
IN1B 5
AGND2 6
24 23 22 21 20 19
18 V
+
17 OUT1
16 V–
15 OUT2
14 V
+
13 OUT3
7
IN2B
8
AGND3
9 10 11 12
+
25
18 OUT2
17 V
+
16 OUT3
15
V
–
14 V
+
13 V
+
V
+
IN3B
IN3B 11
V
–
12
GN PACKAGE
24-LEAD PLASTIC SSOP
UF PACKAGE
24-LEAD (4mm
×
4mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 37°C/W,
θ
JC
= 2.6°C/W
EXPOSED PAD (PIN 25) IS V
–
MUST BE SOLDERED TO PCB
T
JMAX
= 150°C,
θ
JA
= 90°C/W
ORDER PART NUMBER
LT6556CGN
LT6556IGN
GN PART MARKING
LT6556CGN
LT6556IGN
ORDER PART NUMBER
LT6556CUF
LT6556IUF
V
UF PART MARKING*
6556
Order Options
Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
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
= 1k, C
L
= 1.5pF, V
⎯
E
⎯
N
= 0.4V, V
AGND
, V
DGND
, V
VREF
= 0V.
SYMBOL
V
OS
I
IN
R
IN
C
IN
PSRR
PARAMETER
Offset Voltage
Input Current
Input Resistance
Input Capacitance
Power Supply Rejection Ratio
V
IN
= ±1V
f = 100kHz
V
S
= ±2.25V to ±6V (Note 6)
CONDITIONS
V
IN
= 0V, V
OS
= V
OUT
●
●
●
●
●
ELECTRICAL CHARACTERISTICS
MIN
V
–
AGND3 10
EN
V
+
24 V
+
SEL A/B
DGND
IN2A
IN1A
2
U
U
W
W W
U
W
(Note 1)
Junction Temperature
SSOP ................................................................ 150°C
QFN................................................................... 125°C
Storage Temperature Range
SSOP ................................................. –65°C to 150°C
QFN.................................................... –65°C to 125°C
Soldering Temperature (10 sec) ............................ 300°C
TOP VIEW
TYP
18
–12
MAX
±67
±75
±45
UNITS
mV
mV
µA
kΩ
pF
dB
6556f
100
51
500
1
62
LT6556
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
= 1k, C
L
= 1.5pF, V
EN
= 0.4V, V
AGND
, V
DGND
, V
VREF
= 0V.
SYMBOL
I
PSRR
A
V
ERR
A
V
MATCH
V
OUT
I
S
PARAMETER
Input Current Power Supply Rejection
Gain Error
Gain Matching
Output Voltage Swing
Supply Current, Per Amplifier
Supply Current, Disabled, Per Amplifier
I
⎯
E
⎯
N
I
SEL
I
SC
SR
–3dB BW
0.1dB BW
FPBW
Enable Pin Current
Select Pin Current
Output Short-Circuit Current
Slew Rate
Small-Signal –3dB Bandwidth
Gain Flatness ±0.1dB Bandwidth
Full Power Bandwidth 2V
Full Power Bandwidth 4V
All-Hostile Crosstalk
Selected Channel to Unselected
Channel Crosstalk
Channel Select Output Transient
Channel-to-Channel Select Time
t
S
t
R
, t
F
dG
dP
HD2
HD3
Settling Time
Small-Signal Rise and Fall Time
Differential Gain
Differential Phase
2nd Harmonic Distortion
3rd Harmonic Distortion
CONDITIONS
V
S
= ±2.25V to ±6V (Note 6)
V
OUT
= V
REF
= ±2V, Nominal Gain 1V/V
Any One Channel to Another
(Note 7)
R
L
=
∞
V
⎯
E
⎯
N
= 4V, R
L
=
∞
V
⎯
E
⎯
N
= Open, R
L
=
∞
V
⎯
E
⎯
N
= 0.4V
V
⎯
E
⎯
N
= 4V
V
SEL
= 0.4V
V
SEL
= 4V
R
L
= 0Ω, V
IN
= ±2V, V
REF
= ±1V
±1V on ±2.2V Output Step (Note 8)
V
OUT
= 200mV
P-P
V
OUT
= 200mV
P-P
V
OUT
= 2V
P-P
(Note 9)
V
OUT
= 4V
P-P
(Note 9)
f = 10MHz, V
IN
= 2V
P-P
f = 100MHz, V
IN
= 2V
P-P
f = 10MHz, V
IN
= 2V
P-P
f = 100MHz, V
IN
= 2V
P-P
INA = INB = 0V
INA = –1V, INB = 1V
from 50% SEL to V
OUT
= 0V
0.1% of V
FINAL
, V
STEP
= 2V
10% to 90%, V
OUT
= 200mV
P-P
(Note 10)
(Note 10)
f = 10MHz, V
OUT
= 2V
P-P
f = 10MHz, V
OUT
= 2V
P-P
190
●
●
●
●
●
●
●
●
●
●
●
ELECTRICAL CHARACTERISTICS
MIN
–2.8
±3.65
TYP
1
–1.15
±0.05
±3.85
9.5
47
42
MAX
±3
0
UNITS
µA/V
%
%
V
13
14.5
330
330
–200
–75
–50
–50
±50
1200
–95
–21
–5
–1
±105
2100
750
120
335
175
–72
–52
–85
–64
200
8
6.5
500
0.056
0.028
–84
–87
mA
mA
µA
µA
µA
µA
µA
µA
mA
V/µs
MHz
MHz
MHz
MHz
dB
dB
dB
dB
mV
P-P
ns
ns
ps
%
Deg
dBc
dBc
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 LT6556C is guaranteed functional over the operating
temperature range of –40°C to 85°C.
Note 5:
The LT6556C is guaranteed to meet specified performance from
0°C to 70°C. The LT6556C is designed, characterized and expected to
meet specified performance from –40°C and 85°C but is not tested or
QA sampled at these temperatures. The LT6556I is guaranteed to meet
specified performance from –40°C to 85°C.
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
⎯
E
⎯
N 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
⎯
E
⎯
N and SEL pins are
referenced from it.
Note 7:
The V
REF
pin is set to 3V when testing positive swing and –3V
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/(π • 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°.
6556f
3
LT6556
TYPICAL PERFOR A CE CHARACTERISTICS
Supply Current per Amplifier
vs Temperature
12
10
SUPPLY CURRENT (mA)
V
EN
= 0.4V
8
6
4
2
V
EN
= 4V
0
–55 –35 –15
0
5 25 45 65 85 105 125
TEMPERATURE (°C)
6556 G01
V
EN
= 0V
SUPPLY CURRENT (mA)
SUPPLY CURRENT (mA)
Offset Voltage vs Temperature
25
V
S
=
±5V
V
IN
= 0V
INPUT BIAS CURRENT ( A)
0
–5
20
OFFSET VOLTAGE (mV)
EN PIN CURRENT (μA)
15
10
5
0
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
6556 G04
Maximum Output Voltage Swing
vs V
REF
Pin Voltage
5
4
3
OUTPUT VOLTAGE (V)
2
1
0
–1
–2
–3
–4
–5
T
A
= –55°C
LOW SWING
–2 –1.5 –1 –0.5 0 0.5 1
V
REF
PIN VOLTAGE (V)
1.5
2
0
T
A
= 125°C
T
A
= 25°C
T
A
= 25°C
T
A
= 125°C
V
S
=
±5V
R
L
= 1k
HIGH SWING
OUTPUT VOLTAGE (V)
5
T
A
= –55°C
4
OUTPUT VOLTAGE (V)
4
U W
V
S
=
±5V
R
L
=
∞
V
IN
= 0V
Supply Current per Amplifier
vs Supply Voltage
12
V
S
=
±5V
V
EN
, V
IN
, V
DGND
, V
SEL
= 0V
10 T
A
= 25°C
8
6
4
2
12
10
Supply Current per Amplifier
vs
⎯
E
⎯
N Pin Voltage
V
S
=
±5V
R
L
=
∞
V
IN
= 0V
T
A
= –55°C
8
T
A
= 25°C
6
T
A
= 125°C
4
2
0
0
1
2
3 4 5 6 7 8 9 10 11 12
TOTAL SUPPLY VOLTAGE (V)
6556 G02
0
0.5
1.0 1.5 2.0 2.5 3.0
EN PIN VOLTAGE (V)
3.5
4.0
6556 G03
Input Bias Current
vs Temperature
V
S
=
±5V
V
IN
= 1.5V
–10
–15
V
IN
= 0V
–20
V
IN
= –1.5V
–25
–30
–35
–40
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
6556 G05
⎯
E
⎯
N Pin Current vs
⎯
E
⎯
N Pin Voltage
0
–20
–40
–60
–80
T
A
= 25°C
–100
–120
–140
0
1
3
2
EN PIN VOLTAGE (V)
4
5
6556 G06
V
S
=
±5V
V
DGND
= 0V
T
A
= 125°C
T
A
= –55°C
Output Voltage Swing
vs I
LOAD
(Output High)
V
S
=
±5V
V
IN
= 4V
V
VREF
= 3V
T
A
= –55°C
T
A
= 125°C
0
Output Voltage Swing
vs I
LOAD
(Output Low)
V
S
=
±5V
V
IN
= –4V
V
VREF
= –3V
T
A
= 125°C
T
A
= –55°C
–2
T
A
= 25°C
–3
–1
3
2
T
A
= 25°C
1
–4
0
10 20 30 40 50 60 70 80 90 100
SOURCE CURRENT (mA)
6556 G08
–5
0
10 20 30 40 50 60 70 80 90 100
SINK CURRENT (mA)
6556 G09
6556 G07
6556f
LT6556
TYPICAL PERFOR A CE CHARACTERISTICS
Input Noise Spectral Density
1000
INPUT NOISE (nV/√Hz OR pA/√Hz)
1000
V
S
=
±5V
T
A
= 25°C
INPUT IMPEDANCE (kΩ)
100
REJECTION RATIO (dB)
100
e
n
10
i
n
1
0.001
0.01
0.1
1
FREQUENCY (kHz)
10
100
6556 G10
Frequency Response
vs Output Amplitude
3
2
1
0
GAIN (dB)
GAIN (dB)
–1
–2
–3
–4
–5
–6
0.1
1
10
100
FREQUENCY (MHz)
1000
6556 G13
V
S
=
±5V
R
L
= 1k
T
A
= 25°C
0.05
IN1A
0
V
OUT
= 200mV
P-P
V
OUT
= 2V
P-P
V
OUT
= 4V
P-P
–0.10
IN1B
IN2B
IN3B
AMPLITUDE (dB)
Crosstalk vs Frequency
0
V
S
=
±5V
V
OUT
= 2V
P-P
–20 R
L
= 1k
T
A
= 25°C
AMPLITUDE (dB)
AMPLITUDE (dB)
–40
–60
–80
DRIVE IN A;
SELECT IN B
DRIVE IN B;
SELECT IN A
0
DISTORTION (dBc)
–100
–120
0.1
1
10
100
FREQUENCY (MHz)
U W
6556 G16
Input Impedance vs Frequency
V
S
=
±5V
V
IN
= 0V
T
A
= 25°C
70
60
50
40
30
20
10
0.1
0.01
PSRR vs Frequency
±PSRR
–PSRR
+PSRR
V
S
=
±5V
T
A
= 25°C
10
1
0.1
1
10
FREQUENCY (MHz)
100
1000
6556 G11
0
0.001
0.01
0.1
1
FREQUENCY (MHz)
10
100
6556 G12
Gain Flatness vs Frequency
0.15
0.10
V
S
=
±5V
V
OUT
= 200mV
P-P
R
L
= 1k
T
A
= 25°C
9
Frequency Response with
Capacitive Loads
V
S
=
±5V
V
OUT
= 200mV
P-P
R
L
= 1k
T
A
= 25°C
C
L
= 10pF
C
L
= 15pF
C
L
= 6.8pF
6
3
0
C
L
= 3.3pF
–3
C
L
= 0pF
–0.05
IN3A
IN2A
–0.15
0.1
1
10
100
FREQUENCY (MHz)
1000
6556 G14
–6
0.1
1
10
100
FREQUENCY (MHz)
1000
6555 G15
Crosstalk vs Frequency
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
–120
0.1
–100
–110
1000
1
10
100
FREQUENCY (MHz)
1000
6556 G17
Harmonic Distortion vs Frequency
V
S
=
±5V
V
OUT
= 2V
P-P
R
L
= 1k
T
A
= 25°C
V
S
=
±5V
V
OUT
= 2V
P-P
–20 R
L
= 1k
T
A
= 25°C
–40
–60
–80
WORST
ADJACENT
ALL CHANNELS
DRIVEN
HD2
HD3
–120
0.01
0.1
1
10
FREQUENCY (MHz)
100
6556 G18
6556f
5
嵌入式系统
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