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LT6557 500MHz, 2200V/s Gain of 2, Single Supply Triple Video Amplifier with Input Bias Control FEATURES

DESCRIPTION
The LT(R)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/s 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 x 3mm DFN packages.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.
-3dB Small-Signal Bandwidth: 500MHz -3dB 2VP-P Large-Signal Bandwidth: 400MHz Slew Rate: 2200V/s 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: -40C to 85C Available in 16-Lead SSOP and 5mm x 3mm DFN Packages
APPLICATIONS

LCD Video Projectors RGB HD Video Amplifiers Coaxial Cable Drivers Low Supply ADC Drivers
TYPICAL APPLICATION
AC-Coupled Triple Video Driver
EN GND 22F IN R 75 IN R LT6557 BCV V+ OUT R 500 5V 75 220F 412
Fast Large-Signal Transient Response
GND R 500
+ -
V+ R
75 5V
22F IN G 75 IN G
GND G 500
+ -
OUT G 500
75
220F
V+ G
75 5V
22F IN B 75 IN B
GND B 500
+ -
OUT B 500
75
220F
V+ B
75 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) ... -40C to 85C Specified Temperature Range (Note 4) .... -40C to 85C
Junction Temperature SSOP ................................................................ 150C DFN ................................................................... 125C Storage Temperature Range SSOP ................................................. -65C to 150C DFN.................................................... -65C to 125C Lead Temperature (Soldering, 10 sec) SSOP ................................................................ 300C
PACKAGE/ORDER INFORMATION
TOP VIEW TOP VIEW EN GND IN R GND R IN G GND G IN B GND B 1 2 3 4 5 6 7 8 G = +2 G = +2 G = +2 16 BCV 15 V+ 14 OUT R 13 V+ R 12 OUT G 11 V+ G 10 OUT B 9 V+ B EN GND IN R GND R IN G GND G IN B GND B 1 2 3 4 5 6 7 8 G = +2 G = +2 17 G = +2 16 BCV 15 V+ 14 OUT R 13 V+ R 12 OUT G 11 V+ G 10 OUT B 9 V+ B
GN PACKAGE 16-LEAD PLASTIC SSOP TJMAX = 150C, JA = 110C/W
DHC PACKAGE 16-LEAD (5mm x 3mm) PLASTIC DFN TJMAX = 125C, JA = 40C/W EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB
ORDER PART NUMBER LT6557CGN LT6557IGN
GN PART MARKING 6557 6557I
ORDER PART NUMBER LT6557CDHC LT6557IDHC
DHC PART MARKING* 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.
The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VS = 5V, RL = 150 to VS/2, VEN = 0.4V, RBCV = open, unless otherwise noted.
SYMBOL VOS IIN RIN CIN PARAMETER Input Offset Voltage Input Current Input Resistance Input Capacitance CONDITIONS VIN = 1.25V VIN = 1.25V VIN = 0.75V to 1.75V, BCV (Pin 6) Open f = 1MHz

ELECTRICAL CHARACTERISTICS
MIN
TYP 12 15 35 45
MAX 40 50 70 100
UNITS mV mV A A k k pF
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90 50
200 150 1.5
2
LT6557
The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VS = 5V, RL = 150 to VS/2, VEN = 0.4V, RBCV = open, unless otherwise noted.
SYMBOL AV ERR AV MATCH VIN(DC) PSRR VOL VOH IS PARAMETER Gain Error Gain Match Between Channels Input Voltage Bias Power Supply Rejection Ratio Output Voltage Swing Low
ELECTRICAL CHARACTERISTICS
CONDITIONS VIN = 0.75V to 1.75V VIN = 0.75V to 1.75V RBCV = 348 VS = 4V to 6V, VIN = 1.25V

MIN
TYP 0.5 0.5 0.4 0.4
MAX 2.5 3.0 2.75 3.25 1.5 1.7
UNITS % % % % V V dB dB
1.0 0.8 42 38
1.25 1.10 50 47 0.8 0.9
0.9 1.0
V V V V
Output Voltage Swing High
4.1 4.0
4.2 4.1 22.5 25.0 10 10 25 29 450 1000
Supply Current per Amplifier Total Supply Current (Disabled)
VEN = 0.4V, RL = , Includes IS of V+ (Pin 15) VEN = Open, RL = VEN = 0.4V

mA mA A A A A mA mA V/s MHz MHz MHz MHz dB dB ns ns ps % Deg dBc dBc
IEN ISC SR -3dB BW 0.1dB BW FPBW XTalk tS tr, tf G HD2 HD3
Enable Pin Current Short-Circuit Current Slew Rate -3dB Bandwidth Gain Flatness 0.1dB Bandwidth Full Power Bandwidth All Hostile Crosstalk Settling Time Rise Time, Fall Time Differential Gain Differential Phase 2nd Harmonic Distortion 3rd Harmonic Distortion
-250 -300 70 40 1400
-125 -150 100 90 2200 400 500 120
VOUT = 1.25V to 3.75V (Note 5) VOUT = 2VP-P VOUT = 0.2VP-P VOUT = 2VP-P VOUT = 2VP-P (Note 6) f = 10MHz, VOUT = 2VP-P f = 100MHz, VOUT = 2VP-P To 1%, VOUT = 1.5V to 3.5V To 0.1% 10% to 90%, VOUT = 1.5V to 3.5V NTSC Signal NTSC Signal f = 10MHz, VOUT = 2VP-P f = 10MHz, VOUT = 2VP-P
220
350 -80 -55 4 7 875 0.02 0.05 -68 -75
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 -40C and 85C. Note 4: The LT6557C is guaranteed to meet specified performance from 0C to 70C. The LT6557C is designed, characterized and expected to
meet specified performance from -40C to 85C but is not tested or QA sampled at these temperatures.The LT6557I is guaranteed to meet specified performance from -40C to 85C. 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/( * 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
50 45 40 SUPPLY CURRENT (mA) 35 30 25 20 15 10 5 0 0 1 2 6 3 4 5 SUPPLY VOLTAGE (V) 7 8 VOUT = VS/2
Supply Current per Ampifier vs Temperature
Supply Current per Ampifier vs EN Voltage
6557 G04
EN Pin Current vs EN Pin Voltage
Input Referred Offset Voltage vs Temperature
Input Bias Current vs Input 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 Large-Signal Group Delay Crosstalk Between Amplifiers vs Frequency
Output Impedance vs Frequency
Input Impedance vs Frequency
PSRR vs Frequency
Distortion vs Frequency
Distortion vs Frequency
Input Referred Noise Spectral Density
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LT6557 TYPICAL PERFORMANCE CHARACTERISTICS
Overdriven Output Recovery
5 VIN VIN = 0.5V/DIV, VOUT = 1V/DIV 4 VOUT 5 4 3 VOLTAGE (V) 3 2 VOUT 1 1 VS = 5V VIN = 2.4VP-P RL = 1509 0 25 50 75 100 125 150 175 200 225 250 TIME (ns)
6557 G28
Enable/Disable Response
6 VEN(DISABLE)
VS = 5V VOUT = 2VP-P AC COUPLED RL = 150W
2
0 VEN(ENABLE) -1 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 G29
0
Large-Signal Transient Response
2.65
Small-Signal Transient Response
VS = 5V VIN = 50mVP-P RL = 1509
2.60 OUTPUT (V)
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. 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. IN R (Pin 3): Red Channel Input. This pin has a nominal impedance of 200k 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. IN G (Pin 5): Green Channel Input. This pin has a nominal impedance of 200k with input bias circuit inactive, Pin 16 open. 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 B (Pin 7): Blue Channel Input. This pin has a nominal impedance of 200k with input bias circuit inactive, Pin 16 open. 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. OUT G (Pin 12): Green Channel Output. 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 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. 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. 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 150C (SSOP package) or 125C (DFN package), and can be estimated from the ambient temperature (TA) and power dissipation (PD) as follows: TJ = TA + PD * 40C/W for DFN package or TJ = TA + PD * 110C/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 (<0.1 inch) and one or more dedicated ground planes should be employed to minimize parasitic inductance. Poor layout or breadboarding methods can seriously impact amplifier stability, frequency response and crosstalk performance. A 2.2F and a 10F bypass capacitor is recommended for the LT6557supply bus, plus a 10nF high frequency bypass capacitor at each individual power pin.
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LT6557 APPLICATIONS INFORMATION
Programmable Input Bias The LT6557 contains circuitry that provides a user-programmed bias voltage to the inputs of all three amplifier sections. The internal biasing feature is designed to minimize external component count in AC-coupled applications, but may be defeated if external biasing is desired. Figure 1 shows the simplified equivalent circuit feeding the noninverting input of each amplifier. A programming resistor from Pin 16 to GND (Pin 2) establishes the nominal
V+
no-signal amplifier input bias condition according to the following relationship:
VBIAS(IN) = VPIN16 * 9.1k RSET
where VPIN16 = 0.048V typical. For single 5V supply operation, a 400 programming resistor is generally optimal. In applications that demand maximum amplifier linearity, or if external biasing is preferred (in DC-coupled applications, for example), the internal biasing circuitry may be disabled by leaving Pin 16 open. With Pin 16 open, input loading is approximately 200k. Shutdown Control
V I = PIN16 RSET
2.5k IN 9.1k
6557 F01
Figure 1. Simplified Programmable Input Bias Circuit Diagram
V+
40k
BIAS CIRCUITRY EN
The LT6557 may be placed into a shutdown mode, where all three amplifier sections are deactivated and power supply draw is reduced to approximately 10A. When the EN pin is left open, an internal 40k pull-up resistor brings the pin to V+ and the part enters the shutdown mode. Pulling the pin more than approximately 1.5V below V+ will enable the LT6557 (see Figure 2 for equivalent circuit). The pull-down current required to activate the part is typically 125A. In most applications, the EN pin is simply connected to ground (for continuous operation) or driven directly by a CMOS-level logic gate (see Figure 3 for examples). Response time is typically 50ns for enabling, and 1s for shutdown. In shutdown mode, the feedback resistors remain connected between the output pins and the individual ground (or V- connected) pins.
Figure 2. Simplified Shutdown Circuit Diagram
V+ 1 EN DISABLE 2 1 DISABLE V+
LT6557
EN
LT6557 2
6557 F03
(3a) Open Drain or Open Collector
(3b) CMOS Gate with Shared Supply
Figure 3. Suitable Shutdown Pin Drive Circuits
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LT6557 SIMPLIFIED SCHEMATIC
V+
EN
BIAS
OUT
IN
500
500
6557 SS
PACKAGE DESCRIPTION
GN Package 16-Lead Plastic SSOP (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1641)
.045 .005 .189 - .196* (4.801 - 4.978) 16 15 14 13 12 11 10 9
.009 (0.229) REF
.254 MIN
.150 - .165 .229 - .244 (5.817 - 6.198) .150 - .157** (3.810 - 3.988)
.0165 .0015
.0250 BSC 1 .015 .004 x 45 (0.38 0.10) .0532 - .0688 (1.35 - 1.75) 23 4 56 7 8 .004 - .0098 (0.102 - 0.249)
RECOMMENDED SOLDER PAD LAYOUT
.007 - .0098 (0.178 - 0.249)
0 - 8 TYP
.016 - .050 (0.406 - 1.270) NOTE: 1. CONTROLLING DIMENSION: INCHES INCHES 2. DIMENSIONS ARE IN (MILLIMETERS) 3. DRAWING NOT TO SCALE *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
.008 - .012 (0.203 - 0.305) TYP
.0250 (0.635) BSC
GN16 (SSOP) 0204
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LT6557 PACKAGE DESCRIPTION
DHC Package 16-Lead Plastic DFN (5mm x 3mm)
(Reference LTC DWG # 05-08-1706)
0.65 0.05 3.50 0.05
1.65 0.05 2.20 0.05 (2 SIDES) PACKAGE OUTLINE 0.25 0.05 0.50 BSC 4.40 0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 5.00 0.10 (2 SIDES) R = 0.20 TYP R = 0.115 TYP 9 16 0.40 0.10
3.00 0.10 (2 SIDES) PIN 1 TOP MARK (SEE NOTE 6)
1.65 0.10 (2 SIDES) PIN 1 NOTCH
(DHC16) DFN 1103
8 0.200 REF 0.75 0.05 4.40 0.10 (2 SIDES)
1 0.25 0.05 0.50 BSC
0.00 - 0.05 NOTE: 1. DRAWING PROPOSED TO BE MADE VARIATION OF VERSION (WJED-1) IN JEDEC PACKAGE OUTLINE MO-229 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE
BOTTOM VIEW--EXPOSED PAD
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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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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LT6557 TYPICAL APPLICATION
Split Supply Operation with DC Bias Servo
RELATED PARTS
PART NUMBER LT1399 LT1675 LT6550/LT6551 LT6553 LT6554 LT6555 LT6556 LT6558 DESCRIPTION 300MHz Triple Current Feedback Amplifier 250MHz Triple RGB Multiplexer 3.3V Triple and Quad Video Buffers 650MHz Gain of 2 Triple Video Amplifier 650MHz Gain of 1 Triple Video Amplifier 650MHz Gain of 2 Triple Video Multiplexer 750MHz Gain of 1 Triple Video Multiplexer COMMENTS 0.1dB Gain Flatness to 150MHz, Shutdown 100MHz Pixel Switching, 1100V/s Slew Rate, 16-Lead SSOP 110MHz Gain of 2 Buffers in MS Package Optimized for Driving 75 Cables Performance Similar to the LT6553 with AV = 1, 16-Lead SSOP Optimized for Driving 75 Cables High Slew Rate 2100V/s
550MHz, 2200V/s Gain of 1 Triple Video Amplifier Single Supply with Input Bias Control
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Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 FAX: (408) 434-0507
LT/LWI 0606 * REV A * PRINTED IN USA
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2006

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