LT6557
500MHz, 2200V/µs Gain of 2,
Single Supply Triple Video
Amplifier with Input Bias Control
FEATURES
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DESCRIPTION
–3dB Small-Signal Bandwidth: 500MHz
–3dB 2VP-P Large-Signal Bandwidth: 400MHz
Slew Rate: 2200V/µs
Fixed Gain of 2, No External Resistors Required
AC Coupling with Programmable DC Input Bias
Output Swings to 0.8V of Supply Rails
Full Video Swing with 5V Single Supply
Diff Gain: 0.02%
Diff Phase: 0.05°
Enable/Shutdown Pin
High Output Current: ±100mA
Supply Range: 3V to 7.5V
Operating Temperature Range: –40°C to 85°C
Available in 16-Lead SSOP and 5mm × 3mm DFN
Packages
APPLICATIONS
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LCD Video Projectors
RGB HD Video Amplifiers
Coaxial Cable Drivers
Low Supply ADC Drivers
The LT®6557 is a high speed triple video amplifier with an
internal fixed gain of 2 and a programmable DC input bias
voltage. This amplifier features a 400MHz 2VP-P signal
bandwidth, 2200V/µs slew rate and a unique ability to
drive heavy output loads to 0.8V of the supply rails, making the LT6557 ideal for a single 5V supply, wideband video
application. With just one resistor, the inputs of all three
amplifiers can be programmed to a common voltage level,
simplifying and reducing the need for external circuitry in
the AC-coupled applications. Without the programmable
resistor, the input bias circuit becomes inactive, allowing the
use of an external clamp circuit or direct coupled input.
The LT6557 has separate power supply and ground pins for
each amplifier to improve channel separation and to ease
power supply bypassing. The LT6557 provides uncompromised performance in many high speed applications
where a low voltage, single supply is required.
The LT6557 is available in 16-lead SSOP and 5mm × 3mm
DFN packages.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
AC-Coupled Triple Video Driver
GND
Fast Large-Signal Transient Response
BCV
EN
LT6557
V+
5V
412Ω
22µF
IN R
IN R
75Ω
GND R 500Ω
+
–
OUT R
500Ω
V+ R
75Ω
220µF
75Ω
5V
22µF
IN G
IN G
75Ω
GND G 500Ω
+
–
OUT G
500Ω
V+ G
75Ω
220µF
75Ω
5V
22µF
IN B
IN B
75Ω
GND B 500Ω
+
–
OUT B
500Ω
V+ B
75Ω
220µF
75Ω
5V
6557 TA01a
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LT6557
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Total Supply Voltage (VS+ to GND) ...........................7.5V
Input Current........................................................±10mA
Output Current (Note 2) .......................................±70mA
Output Short-Circuit Duration (Note 2) ............ Indefinite
Operating Temperature Range (Note 3) ... –40°C to 85°C
Specified Temperature Range (Note 4) .... –40°C to 85°C
Junction Temperature
SSOP ................................................................ 150°C
DFN ................................................................... 125°C
Storage Temperature Range
SSOP ................................................. –65°C to 150°C
DFN.................................................... –65°C to 125°C
Lead Temperature (Soldering, 10 sec)
SSOP ................................................................ 300°C
PACKAGE/ORDER INFORMATION
TOP VIEW
TOP VIEW
EN
1
GND
2
IN R
3
GND R
4
IN G
5
GND G
6
IN B
7
GND B
16 BCV
G = +2
15 V+
14 OUT R
G = +2
13 V+ R
12 OUT G
G = +2
8
11 V+ G
10 OUT B
9
V+ B
EN
1
GND
2
16 BCV
17
G = +2
15 V+
14 OUT R
IN R
3
GND R
4
IN G
5
GND G
6
IN B
7
10 OUT B
GND B
8
9
G = +2
13 V+ R
12 OUT G
G = +2
11 V+ G
V+ B
DHC PACKAGE
16-LEAD (5mm × 3mm) PLASTIC DFN
TJMAX = 125°C, θJA = 40°C/W
EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB
GN PACKAGE
16-LEAD PLASTIC SSOP
TJMAX = 150°C, θJA = 110°C/W
ORDER PART NUMBER
GN PART MARKING
ORDER PART NUMBER
DHC PART MARKING*
LT6557CGN
LT6557IGN
6557
6557I
LT6557CDHC
LT6557IDHC
6557
6557
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.
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VS = 5V, RL = 150Ω to VS/2, VEN = 0.4V, RBCV = open, unless
otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
VOS
Input Offset Voltage
VIN = 1.25V
IIN
Input Current
RIN
Input Resistance
CIN
Input Capacitance
VIN = 1.25V
VIN = 0.75V to 1.75V, BCV (Pin 6) Open
f = 1MHz
MIN
TYP
MAX
●
12
15
40
50
mV
mV
●
35
45
70
100
µA
µA
●
90
50
200
150
1.5
UNITS
kΩ
kΩ
pF
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LT6557
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VS = 5V, RL = 150Ω to VS/2, VEN = 0.4V, RBCV = open, unless
otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
AV ERR
Gain Error
VIN = 0.75V to 1.75V
AV MATCH
Gain Match Between Channels
VIN(DC)
Input Voltage Bias
PSRR
Power Supply Rejection Ratio
VOL
Output Voltage Swing Low
VOH
Output Voltage Swing High
IS
Supply Current per Amplifier
MIN
VIN = 0.75V to 1.75V
RBCV = 348Ω
VS = 4V to 6V, VIN = 1.25V
TYP
MAX
UNITS
●
±0.5
±0.5
±2.5
±3.0
%
%
●
±0.4
±0.4
±2.75
±3.25
%
%
1.5
1.7
V
V
●
1.0
0.8
1.25
1.10
●
42
38
50
47
0.8
0.9
●
●
Total Supply Current (Disabled)
VEN = 0.4V, RL = ∞, Includes IS of V+
(Pin 15)
VEN = Open, RL = ∞
IEN
Enable Pin Current
ISC
Short-Circuit Current
SR
Slew Rate
VOUT = 1.25V to 3.75V (Note 5)
–3dB BW
–3dB Bandwidth
VEN = 0.4V
4.1
4.0
dB
dB
0.9
1.0
4.2
4.1
V
V
V
V
●
22.5
25.0
25
29
mA
mA
●
10
10
450
1000
µA
µA
●
–250
–300
–125
–150
µA
µA
●
±70
±40
±100
±90
mA
mA
1400
2200
V/µs
VOUT = 2VP-P
400
MHz
VOUT = 0.2VP-P
500
MHz
120
MHz
350
MHz
0.1dB BW
Gain Flatness ±0.1dB Bandwidth
VOUT = 2VP-P
FPBW
Full Power Bandwidth
VOUT = 2VP-P (Note 6)
XTalk
All Hostile Crosstalk
f = 10MHz, VOUT = 2VP-P
f = 100MHz, VOUT = 2VP-P
–80
–55
dB
dB
tS
Settling Time
To 1%, VOUT = 1.5V to 3.5V
To 0.1%
4
7
ns
ns
tr, tf
Rise Time, Fall Time
10% to 90%, VOUT = 1.5V to 3.5V
875
ps
ΔG
Differential Gain
NTSC Signal
0.02
%
ΔΦ
Differential Phase
NTSC Signal
0.05
Deg
HD2
2nd Harmonic Distortion
f = 10MHz, VOUT = 2VP-P
–68
dBc
HD3
3rd Harmonic Distortion
f = 10MHz, VOUT = 2VP-P
–75
dBc
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: A heat sink may be required to keep the junction temperature
below the Absolute Maximum Rating.
Note 3: The LT6557C is guaranteed functional over the temperature range
of –40°C and 85°C.
Note 4: The LT6557C is guaranteed to meet specified performance from
0°C to 70°C. The LT6557C is designed, characterized and expected to
220
meet specified performance from –40°C to 85°C but is not tested or
QA sampled at these temperatures.The LT6557I is guaranteed to meet
specified performance from –40°C to 85°C.
Note 5: Slew rate is 100% production tested on the R channel and
measured on the rising edge of the output signal. The slew rate of the
falling edge and of the G and B channels is guaranteed through design and
characterization.
Note 6: Large-signal bandwidth is calculated from slew rate:
FPBW = SR/(π • VP-P)
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LT6557
TYPICAL PERFORMANCE CHARACTERISTICS
Gain Error Distribution
Gain Error Matching Distribution
Voltage Gain vs Temperature
Supply Current per Ampifier
vs Supply Voltage
Supply Current per Ampifier
vs Temperature
Supply Current per Ampifier
vs EN Voltage
Input Referred Offset Voltage
vs Temperature
Input Bias Current
vs Input Voltage
50
VOUT = VS/2
45
SUPPLY CURRENT (mA)
40
35
30
25
20
15
10
5
0
0
1
2
6
3
4
5
SUPPLY VOLTAGE (V)
7
8
6557 G04
EN Pin Current vs EN Pin Voltage
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LT6557
TYPICAL PERFORMANCE CHARACTERISTICS
Output Voltage vs Input Voltage
Output Voltage Swing
vs Load Current (Output High)
Output Voltage Swing
vs Load Current (Output Low)
Input Bias Voltage vs Resistance
at BCV Pin
Input Bias Voltage vs Temperature
Bias Control Voltage
vs Temperature
Frequency Response
Frequency Response of Three
Amplifiers
Gain Flatness vs Frequency
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LT6557
TYPICAL PERFORMANCE CHARACTERISTICS
Frequency Response with
Capacitive Loads
Output Impedance vs Frequency
Distortion vs Frequency
Large-Signal Group Delay
Input Impedance vs Frequency
Distortion vs Frequency
Crosstalk Between Amplifiers
vs Frequency
PSRR vs Frequency
Input Referred Noise Spectral
Density
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LT6557
TYPICAL PERFORMANCE CHARACTERISTICS
Overdriven Output Recovery
Enable/Disable Response
6
5
VEN(DISABLE)
5
VOUT
4
VS = 5V
VOUT = 2VP-P
AC COUPLED
RL = 150W
4
VOLTAGE (V)
VIN = 0.5V/DIV, VOUT = 1V/DIV
VIN
3
2
3
2
VOUT
1
1
0
VS = 5V
VIN = 2.4VP-P
RL = 1509
0
0
VEN(ENABLE)
–1
25 50 75 100 125 150 175 200 225 250
TIME (ns)
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2
TIME (ms)
6557 G28
6557 G29
Large-Signal Transient Response
Small-Signal Transient Response
2.65
VS = 5V
VIN = 50mVP-P
RL = 1509
OUTPUT (V)
2.60
2.55
2.50
2.45
0
2
4
6
8 10 12 14 16 18 20 22 24
TIME (ns)
6557 G31
PIN FUNCTIONS
EN (Pin 1): Enable Control Pin. The part is enabled when
this pin is pulled low. An internal pull-up resistor of 40k
will turn the part off if this pin is unconnected.
IN G (Pin 5): Green Channel Input. This pin has a nominal impedance of 200kΩ with input bias circuit inactive,
Pin 16 open.
GND (Pin 2): Ground Reference for Enable Pin (Pin 1)
and Bias Control Voltage Pin (Pin 16). This pin must be
connected externally to ground.
GND G (Pin 6): Ground of Green Channel Amplifier. This
pin is not internally connected to other ground pins and
must be connected externally to ground.
IN R (Pin 3): Red Channel Input. This pin has a nominal
impedance of 200kΩ with input bias circuit inactive,
Pin 16 open.
IN B (Pin 7): Blue Channel Input. This pin has a nominal
impedance of 200kΩ with input bias circuit inactive,
Pin 16 open.
GND R (Pin 4): Ground of Red Channel Amplifier. This pin
is not internally connected to other ground pins and must
be connected externally to ground.
GND B (Pin 8): Ground of Blue Channel Amplifier. This
pin is not internally connected to other ground pins and
must be connected externally to ground.
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LT6557
PIN FUNCTIONS
V+ B (Pin 9): Positive Supply Voltage of Blue Channel
Amplifier. This pin is not internally connected to other
supply voltage pins and must be externally connected to
the supply voltage bus with proper bypassing for best
performance, see Power Supply Considerations.
OUT B (Pin 10): Blue Channel Output.
V+ G (Pin 11): Positive Supply Voltage of Green Channel
Amplifier. This pin is not internally connected to other
supply voltage pins and must be externally connected to
the supply voltage bus with proper bypassing for best
performance, see Power Supply Considerations.
the supply voltage bus with proper bypassing for best
performance, see Power Supply Considerations.
OUT R (Pin 14): Red Channel Output.
V+ (Pin 15): Positive Supply Voltage of Control Circuitry.
This pin is not internally connected to other supply voltage
pins and must be externally connected to supply voltage
bus with proper bypassing for best performance, see
Power Supply Considerations.
OUT G (Pin 12): Green Channel Output.
BCV (Pin 16): Bias Control Voltage. A resistor connected
between Pin 16 and Pin 2 (GND) will generate a DC voltage
bias at the inputs of the three amplifiers for AC coupling
application, see Programmable Input Bias.
V+ R (Pin 13): Positive Supply Voltage of Red Channel
Amplifier. This pin is not internally connected to other
supply voltage pins and must be externally connected to
Exposed Pad (Pin 17, DFN Package): Ground. This pad
must be soldered to PCB and is internally connected to
GND (Pin 2).
APPLICATIONS INFORMATION
Power Supply Considerations
The LT6557 is optimized to provide full video signal swing
output when operated from a standard 5V single supply.
Due to the supply current involved in ultrahigh slew rate
amplifiers like the LT6557, selection of the lowest workable
supply voltage is recommended to minimize heat generation and simplify thermal management. Temperature rise
at the internal devices (TJ) must be kept below 150°C
(SSOP package) or 125°C (DFN package), and can be
estimated from the ambient temperature (TA) and power
dissipation (PD) as follows:
TJ = TA + PD • 40°C/W for DFN package
or
TJ = TA + PD • 110°C/W for SSOP package
where PD = (IS + 0.5 • IO) • VS(TOTAL)
The latter equation assumes (conservatively) that the output
swing is small relative to the supply and RMS load current
(IO) is bidirectional (as with AC coupling).
The grounds are separately pinned for each amplifier to
minimize crosstalk.
Operation from split supplies can be accomplished by
connecting the LT6557 ground pins to the negative rail.
Since the amplifier gain is referenced to its ground pins,
the actual signals are referenced to the negative rail, in
this case, and DC coupled applications need to take this
into consideration. With dual supplies, recommended
voltages range from nominal ±2.5V to ±3.3V.
The ultrahigh frequency (UHF) operating range of the
LT6557 requires that careful printed circuit layout practices be followed to obtain maximum performance. Trace
lengths between power pins and bypass capacitors should
be minimized (