LT6559 Low Cost 5V/±5V 300MHz Triple Video Amplifier in 3mm × 3mm QFN DESCRIPTION FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ 300MHz Bandwidth on Single 5V and ±5V (AV = 1, 2 and –1) 0.1dB Gain Flatness: 150MHz (AV = 1, 2 and –1) High Slew Rate: 800V/µs Wide Supply Range: ±2V to ±6V (Dual Supply) 4V to 12V (Single Supply) 80mA Output Current Low Supply Current: 3.9mA/Amplifier Shutdown Mode Fast Turn-On Time: 30ns Fast Turn-Off Time: 40ns Small 0.75mm Tall 16-Lead 3mm × 3mm QFN Package APPLICATIONS ■ ■ ■ ■ ■ ■ ■ The LT®6559 is a low cost, high speed, triple amplifier that has been optimized for excellent video performance on a single 5V supply, yet fits in the small footprint of a 3mm × 3mm QFN package. With a –3dB bandwidth of 300MHz, a 0.1dB bandwidth of 150MHz, and a slew rate of 800V/µs, the LT6559’s dynamic performance is an excellent match for high speed RGB or YPBPR video applications. For multiplexing applications such as KVM switches or selectable video inputs, each channel has an independent high speed enable/disable pin. Each amplifier will turn on in 30ns and off in 40ns. When enabled, each amplifier draws 3.9mA from a 5V supply. The LT6559 operates on a single supply voltage ranging from 4V to 12V, and on split supplies ranging from ±2V to ±6V. The LT6559 comes in a compact 16-lead 3mm × 3mm QFN package, and operates over a –40°C to 85°C temperature range. The LT6559 is manufactured on Linear Technology’s proprietary complementary bipolar process. RGB/YPBPR Cable Drivers LCD Projectors KVM Switches A/V Receivers MUX Amplifiers Composite Video Cable Drivers ADC Drivers , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. TYPICAL APPLICATION 3-Input Video MUX Cable Driver 5V A EN A + RG 182Ω C 100Ω 1/3 LT6559 – – 5V RF 301Ω 5V + VIN B RG 182Ω 75Ω CABLE EN B 100Ω OUTPUT 200mV/DIV VOUT 1/3 LT6559 – 75Ω – 5V RF 301Ω 5V + VIN C RG 182Ω EN C TIME (10ns/DIV) 100Ω 1/3 LT6559 – – 5V RF 301Ω 6559 TA02 RL = 100Ω RF = RG = 301Ω f = 10MHz 6559 TA01 VIN A Square Wave Response CHANNEL SELECT B 6559f 1 LT6559 ABSOLUTE MAXIMUM RATINGS PACKAGE/ORDER INFORMATION (Note 1) OUT R EN R +IN R –IN R TOP VIEW Total Supply Voltage (V+ to V–) ..............................12.6V Input Current (Note 2)......................................... ±10mA Output Current .................................................. ±100mA Differential Input Voltage (Note 2) ............................±5V Output Short-Circuit Duration (Note 3) ........ Continuous Operating Temperature Range (Note 9) –40°C to 85°C Specified Temperature Range (Note 4) .. –40°C to 85°C Storage Temperature Range.................. –65°C to 125°C Junction Temperature (Note 5) ............................ 125°C 16 15 14 13 12 V + *GND 1 –IN G 2 11 EN G 17 5 6 7 8 EN B OUT B 9 –IN B 10 OUT G *GND 4 +IN B +IN G 3 V– UD PACKAGE 16-LEAD (3mm × 3mm) PLASTIC QFN TJMAX = 125°C, θJA = 68°C/W, θJC = 4.2°C/W EXPOSED PAD (PIN 17) IS V –, MUST BE SOLDERED TO THE PCB ORDER PART NUMBER UD PART MARKING LT6559CUD LCHG 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. * Ground pins are not internally connected. For best channel isolation, connect to ground. 5V ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the specified operating temperature range, otherwise specifications are at TA = 25°C. For each amplifier: VCM = 2.5V, VS = 5V, ⎯E⎯N = 0V, pulse tested, unless otherwise noted. (Note 4) SYMBOL PARAMETER VOS Input Offset Voltage CONDITIONS MIN TYP MAX 1.5 10 12 ● ΔVOS /ΔT Input Offset Voltage Drift IIN+ Noninverting Input Current ● 15 Inverting Input Current mV mV µV/°C 10 25 30 µA µA 10 60 70 4.5 µA µA ⎯ z⎯ nV/√H ● IIN – UNITS ● en Input Noise Voltage Density f = 1kHz, RF = 1k, RG = 10Ω, RS = 0Ω +in Noninverting Input Noise Current Density f = 1kHz 6 ⎯ ⎯z pA/√H –in Inverting Input Noise Current Density f = 1kHz 25 ⎯ ⎯z pA/√H RIN Input Resistance VIN = ±1V 0.14 MΩ CIN Input Capacitance Amplifier Enabled Amplifier Disabled 2.0 2.5 pF pF COUT Output Capacitance Amplifier Disabled 8.5 pF VINH Input Voltage Range, High 3.5 4.0 V VINL Input Voltage Range, Low VOUTH Maximum Output Voltage Swing, High RL = 100k 4.1 4.15 VOUTL Maximum Output Voltage Swing, Low RL = 100k VOUTH Maximum Output Voltage Swing, High RL = 150Ω RL = 150Ω 1.0 0.85 ● 3.85 3.65 3.95 1.5 V V 0.9 V V V 6559f 2 LT6559 5V ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the specified operating temperature range, otherwise specifications are at TA = 25°C. For each amplifier: VCM = 2.5V, VS = 5V, ⎯E⎯N = 0V, pulse tested, unless otherwise noted. (Note 4) SYMBOL PARAMETER CONDITIONS VOUTL Maximum Output Voltage Swing, Low RL = 150Ω RL = 150Ω CMRR Common Mode Rejection Ratio = ±2V to ±5V, ⎯E⎯N = V – Power Supply Rejection Ratio VS ROL Transimpedance, ΔVOUT/ΔIIN– VOUT = 1.5V to 3.5V, RL = 150Ω IOUT Maximum Output Current RL = 0Ω IS Supply Current per Amplifier I⎯E⎯N Enable Pin Current SR Slew Rate (Note 6) tON Turn-On Delay Time (Note 7) tOFF Turn-Off Delay Time (Note 7) tr, tf Small-Signal Rise and Fall Time tPD Propagation Delay os ⎯E⎯N Pin Voltage = 4.5V, RL = 150Ω TYP MAX UNITS 1.05 1.15 1.35 V V ● VCM = 1.5V to 3.5V PSRR Disable Supply Current per Amplifier MIN 40 50 dB 56 70 dB 40 80 kΩ 65 mA ● 3.9 6.1 mA ● 0.1 100 µA 30 µA AV = 10, RL = 150Ω, VS = ±5V 500 V/µs RF = RG = 301Ω, RL = 150Ω, VS = ±5V 30 75 RF = RG = 301Ω, RL = 150Ω, VS = ±5V 40 100 RF = RG = 301Ω, RL = 150Ω, VOUT = 1VP-P, VS = ±5V 1.3 ns RF = RG = 301Ω, RL = 150Ω, VOUT = 1VP-P, VS = ±5V 2.5 ns Small-Signal Overshoot RF = RG = 301Ω, RL = 150Ω, VOUT = 1VP-P, VS = ±5V 10 % tS Settling Time 0.1%, AV = –1V, RF = RG = 301Ω, RL = 150Ω, VS = ±5V 25 ns dG Differential Gain (Note 8) RF = RG = 301Ω, RL = 150Ω, VS = ±5V 0.13 % dP Differential Phase (Note 8) RF = RG = 301Ω, RL = 150Ω, VS = ±5V 0.10 DEG ns ns ±5V ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the specified operating temperature range, otherwise specifications are at TA = 25°C. For each amplifier: VCM = 0V, VS = ±5V, ⎯E⎯N = 0V, pulse tested, unless otherwise noted. (Note 4) SYMBOL PARAMETER VOS Input Offset Voltage ΔVOS/ΔT Input Offset Voltage Drift + CONDITIONS MIN ● TYP MAX 1.5 10 15 UNITS mV µV/°C Noninverting Input Current 10 25 µA IIN– Inverting Input Current 10 60 µA en Input Noise Voltage Density f = 1kHz, RF = 1k, RG = 10Ω, RS = 0Ω +in Noninverting Input Noise Current Density –in IIN 4.5 ⎯ ⎯z nV/√H f = 1kHz 6 ⎯ ⎯z pA/√H Inverting Input Noise Current Density f = 1kHz 25 ⎯ ⎯z pA/√H RIN Input Resistance VIN = ±3.5V 1 MΩ CIN Input Capacitance Amplifier Enabled Amplifier Disabled 2.0 2.5 pF pF COUT Output Capacitance Amplifier Disabled 8.5 pF VINH Input Voltage Range, High VS = ±5V VINL Input Voltage Range, Low VOUTH Maximum Output Voltage Swing, High 3.5 4.0 –4.0 RL = 100k 4.0 4.2 V –3.5 V V 6559f 3 LT6559 ±5V ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the specified operating temperature range, otherwise specifications are at TA = 25°C. For each amplifier: VCM = 0V, VS = ±5V, ⎯E⎯N = 0V, pulse tested, unless otherwise noted. (Note 4) SYMBOL PARAMETER CONDITIONS VOUTL Maximum Output Voltage Swing, Low RL = 100k VOUTH Maximum Output Voltage Swing, High RL = 150Ω RL = 150Ω ● RL = 150Ω RL = 150Ω ● VOUTL CMRR Maximum Output Voltage Swing, Low MIN MAX UNITS –4.0 V 3.6 –3.6 VCM = ±3.5V Common Mode Rejection Ratio 3.4 3.2 TYP –4.2 = ±2V to ±5V, ⎯E⎯N = V – V V –3.4 –3.2 V V 42 52 dB 56 70 dB 40 100 kΩ PSRR Power Supply Rejection Ratio VS ROL Transimpedance, ΔVOUT/ΔIIN– VOUT = ±2V, RL = 150Ω IOUT Maximum Output Current RL = 0Ω IS Supply Current per Amplifier VOUT = 0V ● 4.6 6.5 mA Disable Supply Current per Amplifier ⎯E⎯N Pin Voltage = 4.5V, RL = 150Ω ● 0.1 100 µA 100 mA I⎯E⎯N Enable Pin Current SR Slew Rate (Note 6) AV = 10, RL = 150Ω tON Turn-On Delay Time (Note 7) RF = RG = 301Ω, RL = 150Ω 30 75 ns tOFF Turn-Off Delay Time (Note 7) RF = RG = 301Ω, RL = 150Ω 40 100 ns tr, tf Small-Signal Rise and Fall Time RF = RG = 301Ω, RL = 150Ω, VOUT = 1VP-P 1.3 ns tPD Propagation Delay RF = RG = 301Ω, RL = 150Ω, VOUT = 1VP-P 2.5 ns os Small-Signal Overshoot RF = RG = 301Ω, RL = 150Ω, VOUT = 1VP-P 10 % 500 30 µA 800 V/µs tS Settling Time 0.1%, AV = –1, RF = RG = 301Ω, RL = 150Ω 25 ns dG Differential Gain (Note 8) RF = RG = 301Ω, RL = 150Ω 0.13 % dP Differential Phase (Note 8) RF = RG = 301Ω, RL = 150Ω 0.10 DEG 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: This parameter is guaranteed to meet specified performance through design and characterization. It has not been tested. Note 3: A heat sink may be required depending on the power supply voltage and how many amplifiers have their outputs short circuited. Note 4: The LT6559 is guaranteed to meet specified performance from 0°C to 70°C and is designed, characterized and expected to meet these extended temperature limits, but is not tested or QA sampled at –40°C and 85°C. Note 5: TJ is calculated from the ambient temperature TA and the power dissipation PD according to the following formula: TJ = TA + (PD • 68°C/W) Note 6: At ±5V, slew rate is measured at ±2V on a ±3V output signal. At 5V, slew rate is measured from 2V to 3V on a 1.5V to 3.5V output signal. Slew rate is 100% production tested at ±5V for both the rising and falling edge of the B channel. The slew rate of the R and G channels is guaranteed through design and characterization. Note 7: Turn-on delay time (tON) is measured from control input to appearance of 1V at the output, for VIN = 1V. Likewise, turn-off delay time (tOFF) is measured from control input to appearance of 0.5V on the output for VIN = 0.5V. This specification is guaranteed by design and characterization. Note 8: 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 0.1% and 0.1°. Ten identical amplifier stages were cascaded giving an effective resolution of 0.01% and 0.01°. Note 9: The LT6559 is guaranteed functional over the operating temperature range of –40°C to 85°C. TYPICAL AC PERFORMANCE VS (V) AV RL (Ω) RF (Ω) RG (Ω) SMALL SIGNAL –3dB BW (MHz) SMALL SIGNAL 0.1dB BW (MHz) SMALL SIGNAL PEAKING (dB) ±5, 5 1 150 365 - 300 150 0.05 ±5, 5 2 150 301 301 300 150 0 ±5, 5 –1 150 301 301 300 150 0 6559f 4 LT6559 TYPICAL PERFORMANCE CHARACTERISTICS Closed-Loop Gain vs Frequency (AV = 2) 4 2 8 2 0 GAIN (dB) 10 6 0 –2 4 –2 –4 2 –4 1M 10M 100M FREQUENCY (Hz) VS = ±5V VIN = –10dBm RF = 365Ω RL = 150Ω 1G 1M 10M 100M FREQUENCY (Hz) VS = ±5V VIN = –10dBm RF = RG = 301Ω RL = 150Ω 6559 G01 1M 10M 100M FREQUENCY (Hz) VS = ±5V VIN = –10dBm RF = RG = 301Ω RL = 150Ω 1G 6559 G02 Large-Signal Transient Response (AV = 2) TIME (5ns/DIV) 6559 G04 80 70 HD3 80 90 AV = +1 5 4 TA = 25°C RF = 301Ω RL = 150Ω VS = ± 5V 2 110 100 1000 10000 100000 FREQUENCY (kHz) 6559 G07 60 6 3 100 AV = +2 PSRR (dB) HD2 OUTPUT VOLTAGE (VP-P) 7 60 6559 G06 PSRR vs Frequency 8 TA = 25°C 40 RF = RG = 301Ω RL = 150Ω 50 VS = ± 5V VOUT = 2VPP 10 TIME (5ns/DIV) VS = ±5V VIN = ±2.5V RF = RG = 301Ω RL = 150Ω Maximum Undistorted Output Voltage vs Frequency 30 1 6559 G05 TIME (5ns/DIV) VS = ±5V VIN = ±1.25V RF = RG = 301Ω RL = 150Ω 2nd and 3rd Harmonic Distortion vs Frequency 70 OUTPUT (1V/DIV) OUTPUT (1V/DIV) VS = ±5V VIN = ±2.5V RF = 365Ω RL = 150Ω 1G 6559 G03 Large-Signal Transient Response (AV = –1) OUTPUT (1V/DIV) Large-Signal Transient Response (AV = 1) DISTORTION (dB) Closed-Loop Gain vs Frequency (AV = –1) 4 GAIN (dB) GAIN (dB) Closed-Loop Gain vs Frequency (AV = 1) 1 30 10 100 6559 G08 + PSRR 40 20 10 FREQUENCY (MHz) – PSRR 50 TA = 25°C RF = RG = 301Ω RL = 150Ω AV = +2 0 10k 100k 1M 10M FREQUENCY (Hz) 100M 6559 G09 6559f 5 LT6559 TYPICAL PERFORMANCE CHARACTERISTICS Input Voltage Noise and Current Noise vs Frequency Output Impedance (Disabled) vs Frequency Output Impedance vs Frequency 100 1000 100k 100 – IN +IN 10 EN 1 10 30 10 1 0.1 0.01 10k 100 300 1k 3k 10k 30k 100k FREQUENCY (Hz) OUTPUT IMPEDANCE (DISABLED) (Ω) OUTPUT IMPEDANCE (Ω) 100k 1M 10M FREQUENCY (Hz) Maximum Capacitive Load vs Feedback Resistor RF = R G AV = +2 VS = ± 5V PEAKING ≤ 5dB 900 1500 2100 2700 FEEDBACK RESISTANCE (Ω) 30 20 10 0 100 CAPACITIVE LOAD (pF) 10 – 10 4 EN = 0V 3 2 0 1000 0 2 1 0 –1 –2 RL = 150Ω VS = ± 5V EN = 0V – 30 – 40 EN = –5V – 50 – 60 – 70 –4 –5 50 25 0 75 100 –50 –25 AMBIENT TEMPERATURE (°C) 125 6559 G16 1 2 7 3 5 6 4 SUPPLY VOLTAGE (± V) – 80 – 50 – 25 8 9 6559 G15 Positive Supply Current per Amplifier vs Temperature – 20 ENABLE PIN CURRENT (µA) OUTPUT VOLTAGE SWING (V) 4 Enable Pin Current vs Temperature RL = 150Ω EN = V – 6559 G14 Output Voltage Swing vs Temperature RL = 100k 5 1 6559 G13 –3 6 RF = RG = 301Ω VS = ± 5V OVERSHOOT < 2% 3300 5 100M Supply Current per Amplifier vs Supply Voltage SUPPLY CURRENT (mA) 10 OUTPUT SERIES RESISTANCE (Ω) CAPACITIVE LOAD (pF) 100 1M 10M FREQUENCY (Hz) 6559 G12 40 RL = 100k 1k Capacitive Load vs Output Series Resistor 1000 3 10k 6559 G11 6559 G10 1 300 RF = 365Ω AV = +1 VS = ± 5V 100 100k 100M 50 100 25 75 0 AMBIENT TEMPERATURE (°C) 125 6559 G17 POSITIVE SUPPLY CURRENT PER AMPLIFIER (mA) INPUT NOISE (nV/√Hz OR pA/√Hz) RF = RG = 301Ω AV = +2 VS = ± 5V 5.00 VS = ± 5V EN = – 5V 4.75 4.50 EN = 0 4.25 4.00 3.75 3.50 3.25 3.00 –50 –25 0 50 75 100 25 AMBIENT TEMPERATURE (°C) 125 6559 G18 6559f 6 LT6559 TYPICAL PERFORMANCE CHARACTERISTICS Input Offset Voltage vs Temperature 3.0 Input Bias Currents vs Temperature 15 VS = ± 5V VS = ± 5V 12 INPUT BIAS CURRENT (µA) INPUT OFFSET VOLTAGE (mV) 2.5 2.0 1.5 1.0 0.5 0 IB+ IB– 9 6 3 0 –3 – 0.5 –1.0 – 50 – 25 0 50 75 100 25 AMBIENT TEMPERATURE (°C) –6 –50 –25 125 50 100 25 75 0 AMBIENT TEMPERATURE (°C) 6559 G19 6559 G20 All Hostile Crosstalk ALL HOSTILE CROSSTALK (dB) –10 –20 –30 –40 All Hostile Crosstalk (Disabled) –10 RF = RG = 301Ω RL = 150Ω AV = +2 R G B –20 ALL HOSTILE CROSSTALK (dB) 0 125 –50 –60 –70 –80 –90 –30 –40 RF = RG = 301Ω RL = 150Ω AV = +2 R G B –50 –60 –70 –80 –90 –100 –100 100k 1M 10M FREQUENCY (Hz) 100M 500M –110 100k 1M 10M FREQUENCY (Hz) 6559 G21 100M 500M 6559 G24 Rise Time and Overshoot | | Propagation Delay INPUT 100mV/DIV OUTPUT 200mV/DIV | tPD = 2.5ns TIME (500ps/DIV) AV = +2 RL = 150Ω RF = RG = 301Ω | 6559 G22 os = 10% VOUT 200mV/DIV | t r = 1.3ns | TIME (500ps/DIV) AV = +2 RL = 150Ω RF = RG = 301Ω 6559 G23 6559f 7 LT6559 PIN FUNCTIONS GND (Pins 1, 4): Ground. Not connected internally. OUT G (Pin 10): G Channel Output. –IN G (Pin 2): Inverting Input of G Channel Amplifier. ⎯E⎯N G (Pin 11): G Channel Enable Pin. Logic low to enable. +IN G (Pin 3): Noninverting Input of G Channel Amplifier. V+ (Pin 12): Positive Supply Voltage, Usually 5V. +IN B (Pin 5): Noninverting Input of B Channel Amplifier. OUT R (Pin 13): R Channel Output. –IN B (Pin 6): Inverting Input of B Channel Amplifier. ⎯E⎯N R (Pin 14): R Channel Enable Pin. Logic low to enable. ⎯E⎯N B (Pin 7): B Channel Enable Pin. Logic low to enable. –IN R (Pin 15): Inverting Input of R Channel Amplifier. OUT B (Pin 8): B Channel Output. +IN R (Pin 16): Noninverting Input of R Channel Amplifier. V – (Pin 9): Negative Supply Voltage, Usually Ground or –5V. Exposed Pad (Pin 17): V –. Must Be Soldered to the PCB. APPLICATIONS INFORMATION Feedback Resistor Selection The small-signal bandwidth of the LT6559 is set by the external feedback resistors and the internal junction capacitors. As a result, the bandwidth is a function of the supply voltage, the value of the feedback resistor, the closed-loop gain and the load resistor. Optimized for ±5V and single-supply 5V operation, the LT6559 has a –3dB bandwidth of 300MHz at gains of +1, –1, or +2. Refer to the resistor selection guide in the Typical AC Performance table. Capacitance on the Inverting Input Current feedback amplifiers require resistive feedback from the output to the inverting input for stable operation. Take care to minimize the stray capacitance between the output and the inverting input. Capacitance on the inverting input to ground will cause peaking in the frequency response and overshoot in the transient response. Capacitive Loads The LT6559 can drive many capacitive loads directly when the proper value of feedback resistor is used. The required value for the feedback resistor will increase as load capacitance increases and as closed-loop gain decreases. Alternatively, a small resistor (5Ω to 35Ω) can be put in series with the output to isolate the capacitive load from the amplifier output. This has the advantage that the ampli- fier bandwidth is only reduced when the capacitive load is present. The disadvantage is that the gain is a function of the load resistance. Power Supplies The LT6559 will operate from single or split supplies from ±2V (4V total) to ±6V (12V total). It is not necessary to use equal value split supplies, however the offset voltage and inverting input bias current will change. The offset voltage changes about 600µV per volt of supply mismatch. The inverting bias current will typically change about 2µA per volt of supply mismatch. Slew Rate Unlike a traditional voltage feedback op amp, the slew rate of a current feedback amplifier is dependent on the amplifier gain configuration. In a current feedback amplifier, both the input stage and the output stage have slew rate limitations. In the inverting mode, and for gains of 2 or more in the noninverting mode, the signal amplitude between the input pins is small and the overall slew rate is that of the output stage. For gains less than 2 in the noninverting mode, the overall slew rate is limited by the input stage. The input slew rate of the LT6559 is approximately 600V/µs and is set by internal currents and capacitances. The output slew rate is set by the value of the feedback resistor and 6559f 8 LT6559 APPLICATIONS INFORMATION internal capacitance. At a gain of 2 with 301Ω feedback and gain resistors and ±5V supplies, the output slew rate is typically 800V/µs. Larger feedback resistors will reduce the slew rate as will lower supply voltages. The enable/disable times are very fast when driven from standard 5V CMOS logic. Each amplifier enables in about 30ns (50% point to 50% point) while operating on ±5V supplies (Figure 2). Likewise, the disable time is approximately 40ns (50% point to 50% point) (Figure 3). Enable/Disable Each amplifier of the LT6559 has a unique high impedance, zero supply current mode which is controlled by its own ⎯E⎯N pin. These amplifiers are designed to operate with CMOS logic; the amplifiers draw 0.1µA of current when these pins are high or floated. To activate each amplifier, its ⎯E⎯N pin is normally pulled to a logic low. However, supply current will vary as the voltage between the V+ supply and ⎯E⎯N is varied. As seen in Figure 1, +IS does vary with (V+ – V⎯E⎯N), particularly when the voltage difference is less than 3V. For normal operation, it is important to keep the ⎯E⎯N pin at least 3V below the V+ supply. If a V+ of less than 3V is used, for the amplifier to remain enabled at all times the ⎯E⎯N pin should be tied to the V – supply. The enable pin current is approximately 30µA when activated. If using CMOS open-drain logic, an external 1k pull-up resistor is recommended to ensure that the LT6559 remains disabled regardless of any CMOS drain-leakage currents. 2V OUTPUT 0V 5V EN 0V VS = ±5V VIN = 1V RF = 301Ω RG = 301Ω RL = 100Ω 6559 F02 Figure 2. Amplifier Enable Time, AV = 2 2V OUTPUT 0V 5.0 TA = 25°C V + = 5V 4.5 4.0 V – = 0V +IS (mA) 3.5 3.0 V – = – 5V 2.5 5V EN VS = ±5V VIN = 1V 2.0 1.5 1.0 RF = 301Ω RG = 301Ω RL = 100Ω 6559 F03 0V Figure 3. Amplifier Disable Time, AV = 2 0.5 0 0 1 2 4 3 V + – VEN (V) 5 6 Figure 1. +IS vs (V+ – V⎯E⎯N) 7 6559 F01 Differential Input Signal Swing To avoid any breakdown condition on the input transistors, the differential input swing must be limited to ±5V. In normal operation, the differential voltage between the input pins is small, so the ±5V limit is not an issue. In the disabled mode however, the differential swing can be the same as the input swing, and there is a risk of device breakdown if the input voltage range has not been properly considered. 6559f 9 LT6559 TYPICAL APPLICATIONS 3-Input Video MUX Cable Driver Using the LT6559 to Drive LCD Displays The application on the first page of this data sheet shows a low cost, 3-input video MUX cable driver. The scope photo below (Figure 4) displays the cable output of a 30MHz square wave driving 150Ω. In this circuit the active amplifier is loaded by the sum of RF and RG of each disabled amplifier. Resistor values have been chosen to keep the total back termination at 75Ω while maintaining a gain of 1 at the 75Ω load. The switching time between any two channels is approximately 32ns when both enable pins are driven (Figure 5). Driving a variety of XGA and UXGA LCD displays can be a difficult problem because they are usually a capacitive load of over 300pF, and require fast settling. The LT6559 is particularly well suited for driving these LCD displays because it can drive large capacitive loads with a small series resistor at the output, minimizing settling time. As seen in Figure 6, at a gain of +3 with a 16.9Ω output series resistor and a 330pF load, the LT6559 is capable of settling to 0.1% in 30ns for a 6V step. When building the board, care was taken to minimize trace lengths at the inverting inputs. The ground plane was also pulled a few millimeters away from RF and RG on both sides of the board to minimize stray capacitance. EN A EN B OUTPUT 200mV/DIV OUTPUT RL = 150Ω RF = RG = 301Ω f = 10MHz VS = ±5 VINA = VINB = 2VP-P at 3.58MHz 6559 F04 5ns/DIV Figure 4. Square Wave Response 20ns/DIV 6559 F05 Figure 5. 3-Input Video MUX Switching Response (AV = 2) VIN VOUT VS = ±5 RF = 301Ω 20ns/DIV CL = 330pF RG = 150Ω RS = 16.9Ω 6559 F06 Figure 6. Large-Signal Pulse Response 6559f 10 LT6559 TYPICAL APPLICATIONS Buffered RGB to YPBPR Conversion An LT6559 and an LT1395 can be used to map RGB signals into YPBPR “component” video as shown in Figure 7. The LT1395 performs a weighted inverting addition of all three inputs. The LT1395 output includes an amplification of the R input by: − 324 = − 0 . 30 1 . 07k The amplification of the G input is by: The LT6559 section A1 provides a gain of 2 for the R signal, and performs a subtraction of 2Y from the section A2 output. The output resistor divider provides a scaling factor of 0.71 and forms the 75Ω back-termination resistance. Thus, the signal seen at the terminated load is the desired 0.71(R – Y) = PR. The LT6559 section A3 provides a gain of 2 for the B signal, and also performs a subtraction of 2Y from the section A2 output. The output resistor divider provides a scaling factor of 0.57 and forms the 75Ω back-termination resistance. Thus the signal seen at the terminated load is the desired 0.57(B – Y) = PB. − 324 = − 0 . 59 549 Finally, the B input is amplified by: − 324 = − 0 . 11 2 . 94k For this circuit to develop a normal sync on the Y signal, a normal sync must be inserted on each of the R, G, and B inputs. Alternatively, additional circuitry could be added to inject sync directly at the Y output with controlled current pulses. Therefore, the LT1395 output is: –0.3R – 0.59G – 0.11B = –Y. 75Ω SOURCES This output is further scaled and inverted by –301/150 = –2 by LT6559 section A2, thus producing 2Y. With the division by two that occurs due to the termination resistors, the desired Y signal is generated at the load. + A1 1/3 LT6559 1.07k R R11 80.6Ω – 105Ω PR 261Ω 301Ω 549Ω G 324Ω R12 86.6Ω 2.94k B R13 76.8Ω – 150Ω 301Ω 301Ω LT1395 + – 75Ω A2 1/3 LT6559 Y + 301Ω Y = 0.30R + 0.59G + 0.11B PB = 0.57 (B – Y) PR = 0.71 (R – Y) – ALL RESISTORS 1% VS = ±3V TO ±5V A3 1/3 LT6559 + 301Ω 133Ω PB 174Ω 6559 F07 Figure 7. RGB to YPBPR Conversion 6559f 11 LT6559 TYPICAL APPLICATIONS YPBPR to RGB Conversion Two LT6559s can be used to map the YPBPR “component” video into the RGB color space as shown in Figure 8. The Y input is properly terminated with 75Ω and buffered with a gain of 2 by amplifier A2. The PR input is terminated and buffered with a gain of 2.8 by amplifier A1. The PB input is terminated and buffered with a gain of 3.6 by amplifier A3. Amplifier B1 performs an equally weighted addition of amplifiers A1 and A2 outputs, thereby producing 2(Y + 1.4PR), which generates the desired R signal at the terminated load due to the voltage division by 2 caused by the termination resistors. Amplifier B3 forms the equally weighted addition of amplifiers A2 and A3 outputs, thereby producing 2(Y + 1.8PB), which generates the desired B signal at the terminated load. Amplifier B2 performs a weighted summation of all three inputs. The PB signal is amplified overall by: − 301 • 3 . 6 = 2(− 0 . 34) 1 . 54k The PR signal is amplified overall by: − 301 • 2 . 8 = 2(− 0 . 71) 590 The Y signal is amplified overall by: 1k 301 • 1+ • 2 = 2(1) 1k + 698 590 || 1 . 54k Therefore the amplifier B2 output is: 2(Y – 0.34PB – 0.71PR) which generates the desired G signal at the terminated load. The sync present on the Y input is reconstructed on all three R, G, and B outputs. 301Ω 301Ω – 165Ω B1 1/3 LT6559 301Ω 1k – A1 1/3 LT6559 R = Y + 1.40PR G = Y – 0.34PB – 0.71 PR B = Y + 1.77PB 1k 75Ω 590Ω 301Ω 301Ω – B2 1/3 LT6559 698Ω 75Ω 1k 301Ω 118Ω 75Ω G + + Y 301Ω ALL RESISTORS 1% VS = ±3V TO ±5V 1.54k – A2 1/3 LT6559 R + + PR 75Ω 301Ω 301Ω – – A3 1/3 LT6559 + PB 75Ω B3 1/3 LT6559 1k 75Ω B + 1k 6559 F08 Figure 8. YPBPR to RGB Conversion 6559f 12 LT6559 TYPICAL APPLICATIONS Application (Demo) Boards The DC1063A demo board has been created for evaluating the LT6559 and is available directly from Linear Technology. It has been designed as an RGB video buffer/cable driver, using standard VGA 15-pin D-Sub (HD-15) connectors for input and output signals. All sync signals are also passed directly from the input to the output, so the LT6559’s performance can be determined by applying a 5V supply to the DC1063A demo board and then inserting the board between a computer’s analog video output and a monitor. Schematics for the DC1063A demo board can be found on the back page of this datasheet. As seen in the DC1063A schematic, each amplifier is configured in a gain of 2, with a 75Ω back-termination resulting in a final gain of 1. Each input is properly terminated for 75Ω input impedance with AC coupling capacitors at each input and output. Additionally, for proper operation, the positive input of each amplifier is biased to mid-supply with a high impedance resistor divider. As seen below, the DC1063A is a 2-sided board. 6559 F09 Figure 9. DC1063A Component Locator 6559 F10 Figure 10. DC1063A Top Side 6559 F11 Figure 11. DC1063A Bottom Side 6559f 13 LT6559 SIMPLIFIED SCHEMATIC, each amplifier V+ +IN –IN OUT EN V– 6559 SS 6559f 14 LT6559 PACKAGE DESCRIPTION UD Package 16-Lead Plastic QFN (3mm × 3mm) (Reference LTC DWG # 05-08-1691) 0.70 ±0.05 3.50 ± 0.05 1.45 ± 0.05 2.10 ± 0.05 (4 SIDES) PACKAGE OUTLINE 0.25 ±0.05 0.50 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 3.00 ± 0.10 (4 SIDES) BOTTOM VIEW—EXPOSED PAD PIN 1 NOTCH R = 0.20 TYP OR 0.25 × 45° CHAMFER R = 0.115 TYP 0.75 ± 0.05 15 16 PIN 1 TOP MARK (NOTE 6) 0.40 ± 0.10 1 1.45 ± 0.10 (4-SIDES) 2 (UD16) QFN 0904 0.200 REF 0.00 – 0.05 NOTE: 1. DRAWING CONFORMS TO JEDEC PACKAGE OUTLINE MO-220 VARIATION (WEED-2) 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 0.25 ± 0.05 0.50 BSC 6559f 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. 15 LT6559 TYPICAL APPLICATION DC1063A Demo Circuit Schematic R10 301Ω 16 R1 78.7Ω R5 3.32k C4 22µF 15 12 + 14 13 U1:A LT6559 C7 220µF R16 75Ω ENABLE E1 5V 2mm C10 100nF C11 4.7µF + 9 R6 3.32k C2 22µF R2 78.7Ω R7 3.32k R12 301Ω 3 2 E2 GROUND 12 + 10 C8 220µF R17 75Ω GREEN – R13 301Ω C5 22µF 11 U1:B LT6559 9 C3 22µF R3 78.7Ω R8 3.32k R9 3.32k R14 301Ω 12 5 + 6 C6 22µF R15 301Ω 7 U1:C LT6559 8 – 9 R18 75Ω C9 220µF BLUE + H SYNC V SYNC VIDEO OUT J2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 6559 TA03 VIDEO IN J1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 JP1 RED – R11 301Ω 1 2 3 + R4 3.32k + C1 22µF HD-15-M HD-15-F RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1203/LT1205 150MHz Video Multiplexers 2:1 and Dual 2:1 MUXs with 25ns Switch Time LT1204 4-Input Video MUX with Current Feedback Amplifier Cascadable Enable 64:1 Multiplexing LT1395/LT1396/LT1397 Single/Dual/Quad Current Feedback Amplifiers 400MHz Bandwidth, 0.1dB Flatness >100MHz LT1399 300MHz Triple Current Feedback Amplifier 0.1dB Gain Flatness to 150MHz, Shutdown LT1675/LT1675-1 Triple/Single 2:1 Buffered Video Mulitplexer 2.5ns Switching Time, 250MHz Bandwidth LT1806/LT1807 Single/Dual 325MHz Rail-to-Rail In/Out Op Amp Low Distortion, Low Noise LT1809/LT1810 Single/Dual 180MHz Rail-to-Rail In/Out Op Amp Low Distortion, Low Noise LT6550/LT6551 3.3V Triple and Quad Video Buffers 110MHz Gain of 2 Buffers in MS Package LT6553 650MHz Gain of 2 Triple Video Amplifier LT6554 650MHz Gain of 1 Triple Video Amplifier LT6555 650MHz Gain of 2 Triple 2:1 Video Multiplexor LT6556 750MHz Gain of 1 Triple 2:1 Video Multiplexor LT6557 500MHz Gain of 2 Single-Supply Triple Video Amplifier Optimized for Single 5V Supply, 2200V/µs Slew Rate, Input Bias Control LT6558 550MHz Gain of 1 Single-Supply Triple Video Amplifier Optimized for Single 5V Supply, 2200V/µs Slew Rate, Input Bias Control Same Pinout as the LT6553 but Optimized for High Impedance Loads Same Pinout as the LT6553 but Optimized for High Impedance Loads 6559f 16 Linear Technology Corporation LT 0606 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2006