Datasheet

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LT6555

6555f

APPLICATIO S

DESCRIPTIO

FEATURES

TYPICAL APPLICATIO

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

75Ω 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 500µA 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/µs

■

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

■

≤ 500µA 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

–

INA

INB

75Ω

SELECT A/B

6555 TA01a

AGND

ENABLE

DGND

75Ω

OUT

75Ω

OUT

75Ω

OUT

×2

, LTC and LT are registered trademarks of Linear Technology Corporation.

All other trademarks are the property of their respective owners.

TIME (ns)

OUTPUT (V)

0.6

1.0

1.4

1.8

1.6

6555 G21

0.2

–0.2

0.4

0.8

1.2

–0.4

218

= 0V TO 700mV

= ±5V

= 150Ω

= 25°C

Summary of content (16 pages)

PAGE 1
LT6555 650MHz Gain of 2 Triple 2:1Video Multiplexer U FEATURES DESCRIPTIO ■ 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 75Ω video load and feature a –3dB 2VP-P bandwidth of 450MHz, making them ideal for driving very high resolution video signals.
PAGE 2
LT6555 U W W W ABSOLUTE AXI U RATI GS (Note 1) 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) ...
PAGE 3
LT6555 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, CL = 1.5pF, VEN = 0.4V, VAGND, VDGND, VVREF = 0V. SYMBOL PARAMETER CONDITIONS IS Supply Current, Per Amplifier RL = ∞ MIN TYP MAX 9 12 14 mA mA 47 42 500 500 µA µA ● UNITS Supply Current, Disabled, Per Amplifier VEN = 4V, RL = ∞ VEN = Open, RL = ∞ ● ● IEN Enable Pin Current VEN = 0.
PAGE 4
LT6555 U W TYPICAL PERFOR A CE CHARACTERISTICS Supply Current per Amplifier vs Temperature VEN = 0V VEN = 0.
PAGE 5
LT6555 U W TYPICAL PERFOR A CE CHARACTERISTICS 1000 VS = ±5V TA = 25°C 100 en in 10 0.01 0.1 1 FREQUENCY (kHz) 10 10 1 0.1 0.01 100 0.1 1 10 FREQUENCY (MHz) 100 Frequency Response vs Output Amplitude GAIN (dB) VOUT = 200mVP-P VOUT = 2VP-P 3 VOUT = 4VP-P 2 10 100 FREQUENCY (MHz) 12 6.05 IN1B 6.00 CL = 10pF IN2A 6 CL = 0pF 4 2 IN2B 0 VS = ±5V VOUT = 200mVP-P RL = 150Ω TA = 25°C 1 –2 –4 10 100 FREQUENCY (MHz) –6 0.
PAGE 6
LT6555 U W TYPICAL PERFOR A CE CHARACTERISTICS 1.8 0.4 0.2 0.1 0.01 0.1 1 10 FREQUENCY (MHz) 0.1 0 –0.1 100 1000 –0.4 0 2 4 6 8 10 12 14 16 18 20 TIME (ns) 2 OUTPUT (V) OUTPUT (V) 35 1 0 –1 –2 –1.0 –3 –1.5 –4 8 10 12 14 16 18 20 TIME (ns) 0 2 4 6 10 0 1.5 –1.0 –0.5 0.5 1.0 GAIN ERROR—INDIVIDUAL CHANNEL (%) 6555 G24 INA = 0V TA = 25°C INB = 0V 0.2 1.5 1.0 0.1 0.5 0 0 INB = 300MHz, 1VP-P SINE VS = ±5V RL = 150Ω TA = 25°C INA = 0V –0.
PAGE 7
LT6555 U U U PI FU CTIO S (GN24 Package) IN1A (Pin 1): Channel 1 Input A. This pin has a nominal impedance of 400kΩ and does not have any internal termination resistor. DGND (Pin 2): Digital Ground Reference for Enable Pin. This pin is normally connected to ground. IN2A (Pin 3): Channel 2 Input A. This pin has a nominal impedance of 400kΩ and does not have any internal termination resistor. VREF (Pin 4): Voltage Reference for Input Clamping.
PAGE 8
LT6555 U W U U APPLICATIO S I FOR ATIO Power Supplies The LT6555 is optimized for ±5V supplies but can be operated on as little as ±2.25V or a single 4.5V supply and as much as ±6V or a single 12V supply. Internally, each supply is independent to improve channel isolation. Do not leave any supply pins disconnected or the part may not function correctly! Enable/Shutdown The LT6555 has a shutdown mode controlled by the EN pin and referenced to the DGND pin.
PAGE 9
LT6555 U W U U APPLICATIO S I FOR ATIO V+ 40k IN VREF 40k V– 6555 F01 Figure 1. Simplified Schematic of VREF Pin and Input Clamping VREF voltage to the desired level. The only way to cover the full common mode voltage range of V– + 1V to V+ – 1V is to shift VREF up or down. Note that on a single supply, the unclamped input range limits the output low swing to 2V (1V multiplied by the internal gain of 2). The VREF pin can also be directly driven with a DC source.
PAGE 10
LT6555 U W U U APPLICATIO S I FOR ATIO To maintain the LT6555’s channel isolation, it is beneficial to shield parallel input and parallel output traces using a ground plane or power supply traces. Vias between topside and backside metal may be required to maintain a low inductance ground near the part where numerous traces converge. See Figures 6 and 7 for photos of an optimized layout.
PAGE 11
LT6555 U W U U NUMBER OF DEVICES (n) SERIES RT 2 63.9 3 56.2 4 49.9 Another approach that does not compromise gain accuracy is to connect the outputs directly together before the series termination. In this case, there will be slightly increased output glitching and supply current spiking during the EN pin switching, but the additional output loading will not increase the gain error, and the series termination resistors remain at their ideal value for AC response.
PAGE 12
LT6555 U TYPICAL APPLICATIO E1 EN J1 50Ω BNC 1 EN E4 SEL A/B Z = 50 JP1 3 CONTROL 1 E2 DGND 2 R9 50Ω OPT R8 50Ω OPT 2 EXT ENABLE 5 4 3 2 DGND J8 50Ω BNC 1 SEL A/B Z = 50 3 A R7 B 1 20k VCC JP4 SEL DGND 5 4 3 2 JP2 3 DGND 1 2 FLOAT AGND 3 IN1A IN2A IN3A IN1B IN2B IN3B BNC × 6 5 JP12 1 L1 Z = 75 4 3 2 5 JP13 1 L1 Z = 75 4 3 2 5 JP14 1 L1 Z = 75 4 3 2 5 JP5 1 L1 Z = 75 4 3 2 5 JP6 1 L1 Z = 75 4 3 2 5 JP7 1 L1 Z = 75 4 3 2 JP5 VREF 2 EXT E5 VREF C1 4700pF GND C2 470pF C3 470pF
PAGE 13
V– DGND 1k 46k BIAS V+ SELECT TO OTHER OUTPUT STAGES 770Ω SEL 100Ω TO OTHER INPUT STAGES INA V– V+ VREF V– 40k 40k V REF INB 100Ω V– V+ VREF VREF 360Ω 360Ω 6555 SS V– 360Ω AGND 360Ω OUT V+ W W SI PLIFIED SCHE ATIC EN V+ LT6555 (One channel shown) 6555f 13
PAGE 14
LT6555 U PACKAGE DESCRIPTIO GN Package 24-Lead Plastic SSOP (Narrow .150 Inch) (Reference LTC DWG # 05-08-1641) .337 – .344* (8.560 – 8.738) 24 23 22 21 20 19 18 17 16 15 1413 .033 (0.838) REF .045 ±.005 .229 – .244 (5.817 – 6.198) .254 MIN .150 – .157** (3.810 – 3.988) .150 – .165 1 .0165 ± .0015 2 3 4 5 6 7 8 9 10 11 12 .0250 BSC RECOMMENDED SOLDER PAD LAYOUT .015 ± .004 × 45° (0.38 ± 0.10) .0075 – .0098 (0.19 – 0.25) .0532 – .0688 (1.35 – 1.75) .004 – .0098 (0.102 – 0.
PAGE 15
LT6555 U PACKAGE DESCRIPTIO UF Package 24-Lead Plastic QFN (4mm × 4mm) (Reference LTC DWG # 05-08-1697) 0.70 ±0.05 4.50 ± 0.05 2.45 ± 0.05 3.10 ± 0.05 (4 SIDES) PACKAGE OUTLINE 0.25 ±0.05 0.50 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 4.00 ± 0.10 (4 SIDES) BOTTOM VIEW—EXPOSED PAD 0.75 ± 0.05 R = 0.115 TYP PIN 1 NOTCH R = 0.20 TYP OR 0.35 × 45° CHAMFER 23 24 0.40 ± 0.10 PIN 1 TOP MARK (NOTE 6) 1 2 2.45 ± 0.10 (4-SIDES) (UF24) QFN 0105 0.200 REF 0.00 – 0.05 0.25 ± 0.05 0.50 BSC NOTE: 1.
PAGE 16
LT6555 U TYPICAL APPLICATIO RED 1 GREEN 1 BLUE 1 V+ LT6555 #1 75Ω IN1A IN1B 5V OUT1 ×2 75Ω 75Ω RED 2 GREEN 2 BLUE 2 IN2A IN2B OUT2 ×2 75Ω 75Ω IN3A IN3B 75Ω OUT3 ×2 AGND DGND SEL 75Ω VREF EN ROUT 75Ω V– –2V 5V RED 3 GREEN 3 BLUE 3 IN1A IN1B GOUT 75Ω V+ LT6555 #2 75Ω 75Ω OUT1 ×2 75Ω BOUT 75Ω 75Ω 75Ω RED 4 GREEN 4 BLUE 4 IN2A IN2B OUT2 ×2 75Ω 75Ω IN3A IN3B 75Ω OUT3 ×2 AGND DGND SEL VREF EN SEL0 V– NC75Z14 SEL1 SEL0 OUTPUT 0 0 1 0 1 2 1 0 3 1 1 4 SEL1 6555