LT1398/LT1399/LT1399HV Low Cost Dual and Triple 300MHz Current Feedback Amplifiers with Shutdown U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO 300MHz Bandwidth on ± 5V (AV = 1, 2 and –1) 0.1dB Gain Flatness: 150MHz (AV = 1, 2 and –1) Completely Off in Shutdown, 0µA Supply Current High Slew Rate: 800V/µs Wide Supply Range: ±2V(4V) to ±6V(12V) (LT1398/LT1399) ±2V (4V) to ±7.5V (15V) (LT1399HV) 80mA Output Current Low Supply Current: 4.6mA/Amplifier Fast Turn-On Time: 30ns Fast Turn-Off Time: 40ns 16-Pin Narrow SO/Narrow SSOP Packages U APPLICATIO S ■ ■ ■ ■ ■ RGB Cable Drivers LCD Drivers Spread Spectrum Amplifiers MUX Amplifiers Composite Video Cable Drivers Portable Equipment The LT1398/LT1399 operate on all supplies from a single 4V to ±6V. The LT1399HV operates on all supplies from 4V to ±7.5V. Each amplifier draws 4.6mA when active. When disabled each amplifier draws zero supply current and its output becomes high impedance. The amplifiers turn on in only 30ns and turn off in 40ns, making them ideal in spread spectrum and portable equipment applications. The LT1398/LT1399/LT1399HV are manufactured on Linear Technology’s proprietary complementary bipolar process. The LT1399/LT1399HV are pin-for-pin upgrades to the LT1260 optimized for use on ±5V/±7.5V supplies. , LTC and LT are registered trademarks of Linear Technology Corporation. U ■ The LT ®1399 and LT1399HV contain three independent 300MHz current feedback amplifiers, each with a shutdown pin. The LT1399HV is a higher voltage version of the LT1399. The LT1398 is a two amplifier version of the LT1399. TYPICAL APPLICATIO 3-Input Video MUX Cable Driver A + VIN A RG 200Ω CHANNEL SELECT B C Square Wave Response EN A 97.6Ω 1/3 LT1399 – 75Ω CABLE RF 324Ω VOUT + VIN B RG 200Ω RG 200Ω 75Ω OUTPUT 200mV/DIV 97.6Ω 1/3 LT1399 – + VIN C EN B RF 324Ω TIME (10ns/DIV) 1398/99 TA02 97.6Ω 1/3 LT1399 – RL = 100Ω RF = RG = 324Ω f = 10MHz EN C 1399 TA01 RF 324Ω 1 LT1398/LT1399/LT1399HV W W W AXI U U ABSOLUTE RATI GS (Note 1) Total Supply Voltage (V + to V –) LT1398/LT1399 ................................................ 12.6V LT1399HV ....................................................... 15.5V Input Current (Note 2) ....................................... ±10mA Output Current ................................................. ±100mA Differential Input Voltage (Note 2) ........................... ±5V Output Short-Circuit Duration (Note 3) ........ Continuous Operating Temperature Range ............... – 40°C to 85°C Specified Temperature Range (Note 4) .. – 40°C to 85°C Storage Temperature Range ................ – 65°C to 150°C Junction Temperature (Note 5) ............................ 150°C Lead Temperature (Soldering, 10 sec)................. 300°C W U U PACKAGE/ORDER I FOR ATIO TOP VIEW –IN A 1 +IN A 2 15 OUT A *GND 3 14 V+ *GND 4 13 GND* A 16 EN A ORDER PART NUMBER LT1398CS –IN R 1 +IN R 2 15 OUT R *GND 3 14 V + –IN G 4 12 OUT G 11 V – *GND 5 12 GND* +IN G 5 *GND 6 11 V – *GND 6 +IN B 7 10 OUT B +IN B 7 –IN B 8 –IN B B 8 9 ORDER PART NUMBER TOP VIEW EN B R G B 16 EN R LT1399CGN LT1399CS LT1399HVCS 13 EN G 10 OUT B 9 GN PART MARKING EN B 1399 GN PACKAGE S PACKAGE 16-LEAD PLASTIC SSOP 16-LEAD PLASTIC SO S PACKAGE 16-LEAD PLASTIC SO TJMAX = 150°C, θJA = 100°C/W TJMAX = 150°C, θJA = 120°C/W (GN) TJMAX = 150°C, θJA = 100°C/W (S) *Ground pins are not internally connected. For best channel isolation, connect to ground. Consult factory for Industrial and Military grade parts. ELECTRICAL CHARACTERISTICS (LT1398/LT1399) 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, EN = 0V, pulse tested, unless otherwise noted. (Note 4) SYMBOL PARAMETER VOS Input Offset Voltage CONDITIONS MIN TYP MAX 1.5 10 12 ● ∆VOS/∆T IIN + Input Offset Voltage Drift Noninverting Input Current 10 25 30 µA µA 10 50 60 µA µA ● IIN– Inverting Input Current mV mV µV/°C 15 ● UNITS ● en Input Noise Voltage Density f = 1kHz, RF = 1k, RG = 10Ω, RS = 0Ω + in Noninverting Input Noise Current Density – in Inverting Input Noise Current Density RIN Input Resistance VIN = ±3.5V CIN Input Capacitance Amplifier Enabled Amplifier Disabled COUT Output Capacitance Amplifier Disabled 8.5 pF VINH Input Voltage Range, High VS = ±5V VS = 5V, 0V 4.0 4.0 V V 2 4.5 nV/√Hz f = 1kHz 6 pA/√Hz f = 1kHz 25 pA/√Hz 1 MΩ 2.0 2.5 pF pF ● ● 0.3 3.5 LT1398/LT1399/LT1399HV ELECTRICAL CHARACTERISTICS (LT1398/LT1399) 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, EN = 0V, pulse tested, unless otherwise noted. (Note 4) SYMBOL PARAMETER CONDITIONS VINL Input Voltage Range, Low VS = ±5V VS = 5V, 0V VOUTH Maximum Output Voltage Swing, High VS = ±5V, RL = 100k VS = ±5V, RL = 100k VS = 5V, 0V; RL = 100k VOUTL VOUTH VOUTL Maximum Output Voltage Swing, Low Maximum Output Voltage Swing, High Maximum Output Voltage Swing, Low MIN TYP ● – 3.5 – 4.0 1.0 V V 3.9 3.7 4.2 ● V V V – 4.2 ● – 3.9 – 3.7 VS = ±5V, RL = 150Ω VS = ±5V, RL = 150Ω VS = 5V, 0V; RL = 150Ω 3.6 ● 3.4 3.2 VS = ±5V, RL = 150Ω VS = ±5V, RL = 150Ω VS = 5V, 0V; RL = 150Ω ● VS = ±5V, RL = 100k VS = ±5V, RL = 100k VS = 5V, 0V; RL = 100k 4.2 Common Mode Rejection Ratio VCM = ±3.5V ● – ICMRR Inverting Input Current Common Mode Rejection VCM = ±3.5V VCM = ±3.5V ● PSRR Power Supply Rejection Ratio VS = ±2V to ±5V, EN = V – ● + IPSRR Noninverting Input Current Power Supply Rejection VS = ±2V to ±5V, EN = V – 42 – 3.6 0.6 V V V 52 dB 16 22 µA/V µA/V 1 2 3 µA/V µA/V 2 7 µA/V 10 56 70 ● dB – IPSRR Inverting Input Current Power Supply Rejection AV Large-Signal Voltage Gain ROL Transimpedance, ∆VOUT/∆IIN IOUT Maximum Output Current RL = 0Ω ● IS Supply Current per Amplifier VOUT = 0V ● 4.6 6.5 mA Disable Supply Current per Amplifier EN Pin Voltage = 4.5V, RL = 150Ω ● 0.1 100 µA 30 110 200 µA µA IEN VS = V V V 3.6 – 3.4 – 3.2 UNITS V V V 0.8 CMRR ±2V to ±5V, EN = V – MAX ● VOUT = ±2V, RL = 150Ω – VOUT = ±2V, RL = 150Ω 50 65 40 100 mA ● Slew Rate (Note 6) AV = 10, RL = 150Ω tON Turn-On Delay Time (Note 7) RF = RG = 324Ω, RL = 100Ω tOFF Turn-Off Delay Time (Note 7) tr, tf Small-Signal Rise and Fall Time tPD os tS kΩ 80 Enable Pin Current SR dB 500 800 V/µs 30 75 ns RF = RG = 324Ω, RL = 100Ω 40 100 ns RF = RG = 324Ω, RL = 100Ω, VOUT = 1VP-P 1.3 ns Propagation Delay RF = RG = 324Ω, RL = 100Ω, VOUT = 1VP-P 2.5 ns Small-Signal Overshoot RF = RG = 324Ω, RL = 100Ω, VOUT = 1VP-P 10 % Settling Time 0.1%, AV = – 1, RF = RG = 309Ω, RL = 150Ω 25 ns dG Differential Gain (Note 8) RF = RG = 324Ω, RL = 150Ω 0.13 % dP Differential Phase (Note 8) RF = RG = 324Ω, RL = 150Ω 0.10 DEG 3 LT1398/LT1399/LT1399HV ELECTRICAL CHARACTERISTICS (LT1399HV) The ● denotes specifications which apply over the specified operating temperature range, otherwise specifications are at TA = 25°C. For each amplifier: VCM = 0V, VS = ±7.5V, EN = 0V, pulse tested, unless otherwise noted. (Note 4) SYMBOL PARAMETER VOS Input Offset Voltage CONDITIONS MIN TYP MAX 1.5 10 12 ● ∆VOS/∆T Input Offset Voltage Drift IIN+ Noninverting Input Current 10 25 30 µA µA 10 50 60 µA µA ● IIN– Inverting Input Current mV mV µV/°C 15 ● UNITS ● en Input Noise Voltage Density f = 1kHz, RF = 1k, RG = 10Ω, RS = 0Ω, VS = ±5V + in Noninverting Input Noise Current Density f = 1kHz, VS = ±5V 6 pA/√Hz – in Inverting Input Noise Current Density f = 1kHz, VS = ±5V 25 pA/√Hz RIN Input Resistance VIN = ±6V 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 = ±7.5V VS = 7.5V, 0V ● 6 6.5 6.5 V V VINL Input Voltage Range, Low VS = ±7.5V VS = 7.5V, 0V ● –6 – 6.5 1.0 V V VOUTH Maximum Output Voltage Swing, High VS = ±7.5V, RL = 100k VS = ±7.5V, RL = 100k VS = 7.5V, 0V; RL = 100k 6.4 6.1 6.7 ● V V V – 6.7 ● – 6.4 – 6.1 VS = ±7.5V, RL = 150Ω VS = ±7.5V, RL = 150Ω VS = 7.5V, 0V; RL = 150Ω 5.8 ● 5.4 5.1 VS = ±7.5V, RL = 150Ω VS = ±7.5V, RL = 150Ω VS = 7.5V, 0V; RL = 150Ω ● VOUTL VOUTH VOUTL Maximum Output Voltage Swing, Low Maximum Output Voltage Swing, High Maximum Output Voltage Swing, Low 4.5 ● 0.3 nV/√Hz 6.7 VS = ±7.5V, RL = 100k VS = ±7.5V, RL = 100k VS = 7.5V, 0V; RL = 100k V V V 0.8 V V V 5.8 – 5.4 – 5.1 – 5.8 0.6 V V V 52 dB CMRR Common Mode Rejection Ratio VCM = ±6V ● – ICMRR Inverting Input Current Common Mode Rejection VCM = ±6V VCM = ±6V ● PSRR Power Supply Rejection Ratio VS = ±2V to ±7.5V, EN = V – ● + IPSRR Noninverting Input Current Power Supply Rejection VS = ±2V to ±7.5V, EN = V – – IPSRR Inverting Input Current Power Supply Rejection VS = ±2V to ±7.5V, EN = AV Large-Signal Voltage Gain ROL Transimpedance, ∆VOUT/∆IIN IOUT Maximum Output Current RL = 0Ω ● IS Supply Current per Amplifier VOUT = 0V ● 4.6 7 mA Disable Supply Current per Amplifier EN Pin Voltage = 7V, RL = 150Ω ● 0.1 100 µA 30 110 200 µA µA IEN 16 22 µA/V µA/V 1 2 3 µA/V µA/V 2 7 µA/V 10 56 70 ● V– ● VOUT = ±4.5V, RL = 150Ω – VOUT = ±4.5V, RL = 150Ω Enable Pin Current ● 4 42 50 65 40 100 dB dB kΩ 80 mA LT1398/LT1399/LT1399HV ELECTRICAL CHARACTERISTICS (LT1399HV) The ● denotes specifications which apply over the specified operating temperature range, otherwise specifications are at TA = 25°C. For each amplifier: VCM = 0V, VS = ±7.5V, EN = 0V, pulse tested, unless otherwise noted. (Note 4) SYMBOL PARAMETER CONDITIONS MIN TYP SR Slew Rate (Note 6) AV = 10, RL = 150Ω, VS = ±5V 500 800 tON Turn-On Delay Time (Note 7) RF = RG = 324Ω, RL = 100Ω, VS = ±5V 30 75 ns tOFF Turn-Off Delay Time (Note 7) RF = RG = 324Ω, RL = 100Ω, VS = ±5V 40 100 ns tr, tf Small-Signal Rise and Fall Time RF = RG = 324Ω, RL = 100Ω, VOUT = 1VP-P, VS = ±5V 1.3 ns tPD Propagation Delay RF = RG = 324Ω, RL = 100Ω, VOUT = 1VP-P, VS = ±5V 2.5 ns os Small-Signal Overshoot RF = RG = 324Ω, RL = 100Ω, VOUT = 1VP-P, VS = ±5V 10 % tS Settling Time 0.1%, AV = – 1V, RF = RG = 309Ω, RL = 150Ω, VS = ±5V 25 ns dG Differential Gain (Note 8) RF = RG = 324Ω, RL = 150Ω, VS = ±5V 0.13 % dP Differential Phase (Note 8) RF = RG = 324Ω, RL = 150Ω, VS = ±5V 0.10 DEG 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 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 LT1398/LT1399/LT1399HV are guaranteed to meet specified performance from 0°C to 70°C and are designed, characterized and expected to meet these extended temperature limits, but are not tested at – 40°C and 85°C. Guaranteed I grade parts are available, consult factory. Note 5: TJ is calculated from the ambient temperature TA and the power dissipation PD according to the following formula: LT1398CS, LT1399CS, LT1399HVCS: TJ = TA + (PD • 100°C/W) LT1399CGN: TJ = TA + (PD • 120°C/W) MAX UNITS V/µs Note 6: Slew rate is measured at ±2V on a ±3V output signal. 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°. W U TYPICAL AC PERFOR A CE 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 1 100 365 – 300 150 0.05 ±5 2 100 324 324 300 150 0 ±5 –1 100 309 309 300 150 0 5 LT1398/LT1399/LT1399HV U W TYPICAL PERFOR A CE 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 VS = ±5V FREQUENCY (Hz) VIN = –10dBm RF = 365Ω RL = 100Ω 1G 1M 10M 100M VS = ±5V FREQUENCY (Hz) VIN = –10dBm RF = RG = 324Ω RL = 100Ω 1398/99 G01 1M 10M 100M VS = ±5V FREQUENCY (Hz) VIN = –10dBm RF = RG = 309Ω RL = 100Ω Large-Signal Transient Response (AV = 2) TIME (5ns/DIV) 1398/99 G04 VS = ±5V TIME (5ns/DIV) VIN = ±1.25V RF = RG = 324Ω RL = 100Ω 2nd and 3rd Harmonic Distortion vs Frequency Large-Signal Transient Response (AV = – 1) 70 HD3 80 90 70 AV = +1 100 5 4 10 100 1000 10000 100000 FREQUENCY (kHz) 1398/1399 G07 60 1 100 1398/1399 G08 + PSRR 40 30 10 10 FREQUENCY (MHz) – PSRR 50 20 TA = 25°C RF = 324Ω RL = 100Ω VS = ± 5V 2 110 AV = +2 6 3 1 PSRR vs Frequency 7 HD2 1398/99 G06 80 PSRR (dB) 60 VS = ±5V TIME (5ns/DIV) VIN = ±2.5V RF = RG = 309Ω RL = 100Ω 8 OUTPUT VOLTAGE (VP-P) TA = 25°C 40 RF = RG = 324Ω RL = 100Ω 50 VS = ± 5V VOUT = 2VPP 1398/99 G05 Maximum Undistorted Output Voltage vs Frequency 30 1G 1398/99 G03 OUTPUT (1V/DIV) OUTPUT (1V/DIV) VS = ±5V VIN = ±2.5V RF = 365Ω RL = 100Ω 6 1G 1398/99 G02 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) TA = 25°C RF = RG = 324Ω RL = 100Ω AV = +2 0 10k 100k 1M 10M FREQUENCY (Hz) 100M 1398/1399 G09 LT1398/LT1399/LT1399HV U W TYPICAL PERFOR A CE CHARACTERISTICS Input Voltage Noise and Current Noise vs Frequency 100k 100 100 – IN +IN 10 EN 1 10 30 10 RF = RG = 324Ω RL = 50Ω AV = +2 VS = ± 5V 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 900 1500 2100 2700 FEEDBACK RESISTANCE (Ω) RF = RG = 324Ω VS = ± 5V OVERSHOOT < 2% 30 20 10 100 CAPACITIVE LOAD (pF) 10 4 EN = 0V 3 2 0 1000 0 5 – 10 4 ENABLE PIN CURRENT (µA) 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 1398/1399 G16 2 7 3 5 6 4 SUPPLY VOLTAGE (± V) – 80 – 50 – 25 8 9 Positive Supply Current per Amplifier vs Temperature – 20 2 1 1398/1399 G15 Enable Pin Current vs Temperature RL = 150Ω EN = V – 1398/1399 G14 Output Voltage Swing vs Temperature RL = 100k 5 1 1398/1399 G13 OUTPUT VOLTAGE SWING (V) Supply Current vs Supply Voltage 0 3300 100M 6 SUPPLY CURRENT (mA) RF = RG AV = +2 VS = ± 5V PEAKING ≤ 5dB OUTPUT SERIES RESISTANCE (Ω) CAPACITIVE LOAD (pF) 10 1M 10M FREQUENCY (Hz) 1398/1399 G12 40 100 –3 1k Capacitive Load vs Output Series Resistor 1000 RL = 100k 10k 1398/1399 G11 1398/1399 G10 1 300 RF = 365Ω AV = +1 VS = ± 5V 100 100k 100M 50 100 25 75 0 AMBIENT TEMPERATURE (°C) 125 1398/1399 G17 POSITIVE SUPPLY CURRENT PER AMPLIFIER (mA) INPUT NOISE (nV/√Hz OR pA/√Hz) 1000 3 Output Impedance (Disabled) vs Frequency Output Impedance vs Frequency 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 75 100 0 50 25 AMBIENT TEMPERATURE (°C) 125 1398/1399 G18 7 LT1398/LT1399/LT1399HV U W TYPICAL PERFOR A CE 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+ 9 6 3 IB– 0 –3 – 0.5 –1.0 – 50 – 25 75 100 50 25 AMBIENT TEMPERATURE (°C) 0 –6 –50 –25 125 50 100 25 75 0 AMBIENT TEMPERATURE (°C) 1398/1399 G19 1398/99 G20 All Hostile Crosstalk ALL HOSTILE CROSSTALK (dB) –10 –20 –30 –40 All Hostile Crosstalk (Disabled) –10 RF = RG = 324Ω RL = 100Ω AV = +2 R G B –20 ALL HOSTILE CROSSTALK (dB) 0 125 –50 –60 –70 –80 –90 –30 –40 RF = RG = 324Ω RL = 100Ω 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) 1398/1399 G21 100M 500M 1398/1399 G24 Propagation Delay Rise Time and Overshoot OS = 10% INPUT 100mV/DIV OUTPUT 200mV/DIV tPD = 2.5ns AV = +2 TIME (500ps/DIV) RL = 100Ω RF = RG = 324Ω 8 1398/1399 G22 VOUT 200mV/DIV tr = 1.3ns AV = +2 TIME (500ps/DIV) RL = 100Ω RF = RG = 324Ω 1398/1399 G23 LT1398/LT1399/LT1399HV U U U PIN FUNCTIONS LT1398 LT1399, LT1399HV – IN A (Pin 1): Inverting Input of A Channel Amplifier. – IN R (Pin 1): Inverting Input of R Channel Amplifier. + IN A (Pin 2): Noninverting Input of A Channel Amplifier. + IN R (Pin 2): Noninverting Input of R Channel Amplifier. GND (Pins 3, 4, 5, 6): Ground. Not connected internally. GND (Pin 3): Ground. Not connected internally. + IN B (Pin 7): Noninverting Input of B Channel Amplifier. – IN G (Pin 4): Inverting Input of G Channel Amplifier. – IN B (Pin 8): Inverting Input of B Channel Amplifier. + IN G (Pin 5): Noninverting Input of G Channel Amplifier. EN B (Pin 9): B Channel Enable Pin. Logic low to enable. GND (Pin 6): Ground. Not connected internally. OUT B (Pin 10): B Channel Output. + IN B (Pin 7): Noninverting Input of B Channel Amplifier. V – (Pin 11): Negative Supply Voltage, Usually – 5V. – IN B (Pin 8): Inverting Input of B Channel Amplifier. GND (Pins 12, 13): Ground. Not connected internally. EN B (Pin 9): B Channel Enable Pin. Logic low to enable. V + (Pin 14): Positive Supply Voltage, Usually 5V. OUT B (Pin 10): B Channel Output. OUT A (Pin 15): A Channel Output. V – (Pin 11): Negative Supply Voltage, Usually – 5V. EN A (Pin 16): A Channel Enable Pin. Logic low to enable. OUT G (Pin 12): G Channel Output. EN G (Pin 13): G Channel Enable Pin. Logic low to enable. V + (Pin 14): Positive Supply Voltage, Usually 5V. OUT R (Pin 15): R Channel Output. EN R (Pin 16): R Channel Enable Pin. Logic low to enable. U W U UO APPLICATI S I FOR ATIO Feedback Resistor Selection The small-signal bandwidth of the LT1398/LT1399/ LT1399HV 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. The LT1398/LT1399 have been optimized for ±5V supply operation and have a – 3dB bandwidth of 300MHz at a gain of 2. The LT1399HV provides performance similar to the LT1399. Please 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 LT1398/LT1399/LT1399HV 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 amplifier bandwidth is only reduced when the capacitive load is present. The disadvantage is that the gain is a function of the load resistance. 9 LT1398/LT1399/LT1399HV U W U UO S I FOR ATIO Power Supplies The LT1398/LT1399 will operate from single or split supplies from ±2V (4V total) to ±6V (12V total). The LT1399HV will operate from single or split supplies from ±2V (4V total) to ±7.5V (15V 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 not independent of 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 LT1398/LT1399/LT1399HV 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 internal capacitance. At a gain of 2 with 324Ω 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. Enable/ Disable Each amplifier of the LT1398/LT1399/LT1399HV has a unique high impedance, zero supply current mode which is controlled by its own EN pin. These amplifiers are designed to operate with CMOS logic; the amplifiers draw zero current when these pins are high. To activate each amplifier, its EN pin is normally pulled to a logic low. However, supply current will vary as the voltage between the V + supply and EN is varied. As seen in Figure 1, +I S does vary with (V + – VEN), particularly when the voltage difference is less than 3V. For normal operation, it is important to keep the EN pin at least 3V below the V + supply. If a V + of less than 3V is desired, and the amplifier 10 will remain enabled at all times, then the EN 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 LT1399 remains disabled in spite of any CMOS drain-leakage currents. 5.0 TA = 25°C V + = 5V 4.5 4.0 V – = 0V 3.5 +IS (mA) APPLICATI 3.0 V – = – 5V 2.5 2.0 1.5 1.0 0.5 0 0 1 2 4 3 V + – VEN (V) 5 6 7 1398/99 F01 Figure 1. + IS vs (V + – VEN) OUTPUT EN VS = ±5V VIN = 1V RF = 324Ω RG = 324Ω RL = 100Ω 1398/99 F02 Figure 2. Amplifier Enable Time, AV = 2 OUTPUT EN VS = ±5V VIN = 1V RF = 324Ω RG = 324Ω RL = 100Ω 1398/99 F03 Figure 3. Amplifier Disable Time, AV = 2 LT1398/LT1399/LT1399HV W U U UO APPLICATI S I FOR ATIO 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). EN A EN B OUTPUT 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 input voltage range has not been properly considered. 3-Input Video MUX Cable Driver 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. When building the board, care was taken to minimize trace lengths at the inverting input. The ground plane was also pulled away from RF and RG on both sides of the board to minimize stray capacitance. VS = ±5V VINA = VINB = 2VP-P at 3.58MHz 1398/99 F05 20ns/DIV Figure 5. 3-Input Video MUX Switching Response (AV = 2) Using the LT1399 to Drive LCD Displays Driving the current crop of XGA and UXGA LCD displays can be a difficult problem because they require drive voltages of up to 12V, are usually a capacitive load of over 300pF, and require fast settling. The LT1399HV is particularly well suited for driving these LCD displays because it is capable of swinging more than ±6V on ±7.5V supplies, and it can drive large capacitive loads with a small series resistor at the output, minimizing settling time. As seen in Figures 6 and 7, at a gain of +3 with a 16.9Ω output series resistor and a 330pF load, the LT1399HV is capable of settling to 0.1% in 30ns for a 6V step. Similarly, a 12V output step settles in 70ns. VIN VOUT OUTPUT 200mV/DIV VS = ±5V RF = 324Ω RG = 162Ω RS = 16.9Ω CL = 330pF 20ns/DIV 1398/99 AI06 Figure 6. LT1399/LT1399HV Large-Signal Pulse Response RL = 150Ω RF = RG = 324Ω f = 10MHz 5ns/DIV 1398/99 F04 Figure 4. Square Wave Response 11 LT1398/LT1399/LT1399HV W U U UO APPLICATI S I FOR ATIO resistor R11, which yields a 75Ω input impedance at the R input when considered in parallel with R8. R8 connects to the inverting input of a second LT1398 amplifier (A2), which also sums the weighted G and B inputs to create a –0.5 • Y output. LT1398 amplifier B1 then takes the –0.5 • Y output and amplifies it by a gain of –2, resulting in the Y output. Amplifier A1 is configured in a noninverting gain of 2 with the bottom of the gain resistor R2 tied to the Y output. The output of amplifier A1 thus results in the color-difference output R-Y. VIN VOUT VS = ±7.5V RF = 324Ω RG = 162Ω RS = 16.9Ω CL = 330pF 1398/99 F07 50ns/DIV Figure 7. LT1399HV Output Voltage Swing Buffered RGB to Color-Difference Matrix Two LT1398s can be used to create buffered colordifference signals from RGB inputs (Figure 8). In this application, the R input arrives via 75Ω coax. It is routed to the noninverting input of LT1398 amplifier A1 and to a 1082Ω resistor R8. There is also an 80.6Ω termination The B input is similar to the R input. It arrives via 75Ω coax, and is routed to the noninverting input of LT1398 amplifier B2, and to a 2940Ω resistor R10. There is also a 76.8Ω termination resistor R13, which yields a 75Ω input impedance when considered in parallel with R10. R10 also connects to the inverting input of amplifier A2, adding the B contribution to the Y signal as discussed above. Amplifier B2 is configured in a noninverting gain of 2 configuration with the bottom of the gain resistor R4 tied to the Y output. The output of amplifier B2 thus results in the color-difference output B-Y. + 75Ω SOURCES R8 1082Ω A1 1/2 LT1398 R R11 80.6Ω – R1 324Ω R9 549Ω R7 324Ω G R12 86.6Ω R-Y R10 2940Ω B R13 76.8Ω – A2 1/2 LT1398 + R6 162Ω R5 324Ω R2 324Ω – B1 1/2 LT1398 Y + R4 324Ω – ALL RESISTORS 1% VS = ±5V B2 1/2 LT1398 + Figure 8. Buffered RGB to Color-Difference Matrix 12 R3 324Ω B-Y 1398/99 F08 LT1398/LT1399/LT1399HV U W U UO APPLICATI S I FOR ATIO The G input also arrives via 75Ω coax and adds its contribution to the Y signal via a 549Ω resistor R9, which is tied to the inverting input of amplifier A2. There is also an 86.6Ω termination resistor R12, which yields a 75Ω termination when considered in parallel with R9. Using superposition, it is straightforward to determine the output of amplifier A2. Although inverted, it sums the R, G and B signals in the standard proportions of 0.3R, 0.59G and 0.11B that are used to create the Y signal. Amplifier B1 then inverts and amplifies the signal by 2, resulting in the Y output. R10, giving an amplification of – 0.37. This results in a contribution at the output of A2 of 0.37Y – 0.37B. If we now sum the three contributions at the output of A2, we get: A2OUT = 3.40Y – 1.02R – 0.37B It is important to remember though that Y is a weighted sum of R, G and B such that: Y = 0.3R + 0.59G + 0.11B If we substitute for Y at the output of A2 we then get: A2OUT = (1.02R – 1.02R) + 2G + (0.37B – 0.37B) = 2G Buffered Color-Difference to RGB Matrix The LT1399 can be used to create buffered RGB outputs from color-difference signals (Figure 9). The R output is a back-terminated 75Ω signal created using resistor R5 and LT1399 amplifier A1 configured for a gain of +2 via 324Ω resistors R3 and R4. The noninverting input of amplifier A1 is connected via 1k resistors R1 and R2 to the Y and R-Y inputs respectively, resulting in cancellation of the Y signal at the amplifier input. The remaining R signal is then amplified by A1. The back-termination resistor R11 then halves the output of A2 resulting in the G output. R1 1k Y R2 1k A1 1/3 LT1399 R-Y – The B output is also a back-terminated 75Ω signal created using resistor R16 and amplifier A3 configured for a gain of +2 via 324Ω resistors R14 and R15. The noninverting input of amplifier A3 is connected via 1k resistors R12 and R13 to the Y and B-Y inputs respectively, resulting in cancellation of the Y signal at the amplifier input. The remaining B signal is then amplified by A3. The G output is the most complicated of the three. It is a weighted sum of the Y, R-Y and B-Y inputs. The Y input is attenuated via resistors R6 and R7 such that amplifier A2’s noninverting input sees 0.83Y. Using superposition, we can calculate the positive gain of A2 by assuming that R8 and R9 are grounded. This results in a gain of 2.41 and a contribution at the output of A2 of 2Y. The R-Y input is amplified by A2 with the gain set by resistors R8 and R10, giving an amplification of –1.02. This results in a contribution at the output of A2 of 1.02Y – 1.02R. The B-Y input is amplified by A2 with the gain set by resistors R9 and + R R3 324Ω R4 324Ω R6 205Ω + R7 1k R8 316Ω R5 75Ω A2 1/3 LT1399 – R11 75Ω G R10 324Ω R9 845Ω B-Y R12 1k R13 1k ALL RESISTORS 1% VS = ± 5V + A3 1/3 LT1399 – R16 75Ω B R14 324Ω R15 324Ω 1398/99 F09 Figure 9. Buffered Color-Difference to RGB Matrix 13 LT1398/LT1399/LT1399HV W W SI PLIFIED SCHE ATIC , each amplifier V+ +IN –IN OUT EN V– 14 1398/99 SS LT1398/LT1399/LT1399HV U PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted. GN Package 16-Lead Plastic SSOP (Narrow 0.150) (LTC DWG # 05-08-1641) 0.189 – 0.196* (4.801 – 4.978) 0.009 (0.229) REF 16 15 14 13 12 11 10 9 0.229 – 0.244 (5.817 – 6.198) 0.150 – 0.157** (3.810 – 3.988) 1 0.015 ± 0.004 × 45° (0.38 ± 0.10) 0.007 – 0.0098 (0.178 – 0.249) 4 2 3 5 6 7 0.053 – 0.068 (1.351 – 1.727) 8 0.004 – 0.0098 (0.102 – 0.249) 0° – 8° TYP 0.016 – 0.050 (0.406 – 1.270) 0.025 (0.635) BSC 0.008 – 0.012 (0.203 – 0.305) * 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 GN16 (SSOP) 0398 S Package 16-Lead Plastic Small Outline (Narrow 0.150) (LTC DWG # 05-08-1610) 0.386 – 0.394* (9.804 – 10.008) 16 15 14 13 12 11 10 9 0.150 – 0.157** (3.810 – 3.988) 0.228 – 0.244 (5.791 – 6.197) 1 0.010 – 0.020 × 45° (0.254 – 0.508) 0.008 – 0.010 (0.203 – 0.254) 2 3 4 5 6 0.053 – 0.069 (1.346 – 1.752) 0.014 – 0.019 (0.355 – 0.483) 8 0.004 – 0.010 (0.101 – 0.254) 0° – 8° TYP 0.016 – 0.050 0.406 – 1.270 7 0.050 (1.270) TYP S16 0695 *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 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 LT1398/LT1399/LT1399HV UO TYPICAL APPLICATI Single Supply RGB Video Amplifier input. Assuming a 75Ω source impedance for the signal driving VIN, the Thevenin equivalent signal arriving at A1’s positive input is 3V + 0.4VIN, with a source impedance of 714Ω. The combination of these two inputs gives an output at the cathode of D2 of 2 • VIN with no additional DC offset. The 75Ω back termination resistor R9 halves the signal again such that VOUT equals a buffered version of VIN. The LT1399 can be used with a single supply voltage of 6V or more to drive ground-referenced RGB video. In Figure 10, two 1N4148 diodes D1 and D2 have been placed in series with the output of the LT1399 amplifier A1 but within the feedback loop formed by resistor R8. These diodes effectively level-shift A1’s output downward by 2 diodes, allowing the circuit output to swing to ground. It is important to note that the 4.7µF capacitor C1 has been added to provide enough current to maintain the voltage drop across diodes D1 and D2 when the circuit output drops low enough that the diodes might otherwise reverse bias. This means that this circuit works fine for continuous video input, but will require that C1 charge up after a period of inactivity at the input. Amplifier A1 is used in a positive gain configuration. The feedback resistor R8 is 324Ω. The gain resistor is created from the parallel combination of R6 and R7, giving a Thevenin equivalent 80.4Ω connected to 3.75V. This gives an AC gain of + 5 from the noninverting input of amplifier A1 to the cathode of D2. However, the video input is also attenuated before arriving at A1’s positive 5V R1 1000Ω R6 107Ω + A1 1/3 LT1399 R2 1300Ω – R3 160Ω VIN R4 75Ω R5 2.32Ω C1 4.7µF VS 6V TO 12V D2 D1 1N4148 1N4148 R9 75Ω VOUT R8 324Ω 1398/99 F10 R7 324Ω Figure 10. Single Supply RGB Video Amplifier (1 of 3 Channels) 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 LT1227 140MHz Current Feedback Amplifier 1100V/µs Slew Rate, Shutdown Mode LT1252/LT1253/LT1254 Low Cost Video Amplifiers Single, Dual and Quad Current Feedback Amplifiers LT1259/LT1260 Dual/Triple Current Feedback Amplifier 130MHz Bandwidth, 0.1dB Flatness > 30MHz LT1675 Triple 2:1 Buffered Video Mulitplexer 2.5ns Switching Time, 250MHz Bandwidth 16 Linear Technology Corporation 13989f LT/TP 0699 4K • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com LINEAR TECHNOLOGY CORPORATION 1998