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LT1398/LT1399/LT1399HV Low Cost Dual and Triple 300MHz Current Feedback Amplifiers with Shutdown
FEATURES
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DESCRIPTIO
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300MHz Bandwidth on 5V (AV = 1, 2 and -1) 0.1dB Gain Flatness: 150MHz (AV = 1, 2 and -1) Completely Off in Shutdown, 0A Supply Current High Slew Rate: 800V/s 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
The LT (R)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. 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.
APPLICATIO S
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RGB Cable Drivers LCD Drivers Spread Spectrum Amplifiers MUX Amplifiers Composite Video Cable Drivers Portable Equipment
TYPICAL APPLICATIO
A VIN A RG 200 CHANNEL SELECT EN A BC
3-Input Video MUX Cable Driver Square Wave Response
97.6
+ -
1/3 LT1399 RF 324 75 CABLE VOUT
VIN B RG 200
+ -
EN B 97.6
75
OUTPUT 200mV/DIV
1/3 LT1399 RF 324
VIN C RG 200
+ -
EN C 97.6
1399 TA01
RL = 100 RF = RG = 324 f = 10MHz
1/3 LT1399 RF 324
U
TIME (10ns/DIV)
1398/99 TA02
U
U
1
LT1398/LT1399/LT1399HV ABSOLUTE AXI U RATI GS
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
PACKAGE/ORDER I FOR ATIO
TOP VIEW -IN A +IN A *GND *GND *GND *GND +IN B -IN B 1 2 3 4 5 6 7 8 B A 16 EN A 15 OUT A 14 V+
ORDER PART NUMBER LT1398CS
13 GND* 12 GND* 11 V - 10 OUT B 9 EN B
S PACKAGE 16-LEAD PLASTIC SO TJMAX = 150C, JA = 100C/W
*Ground pins are not internally connected. For best channel isolation, connect to ground. Consult factory for Industrial and Military grade parts.
(LT1398/LT1399) The q denotes specifications which apply over the specified operating temperature range, otherwise specifications are at TA = 25C. For each amplifier: VCM = 0V, VS = 5V, EN = 0V, pulse tested, unless otherwise noted. (Note 4)
SYMBOL VOS VOS/T IIN
+
ELECTRICAL CHARACTERISTICS
PARAMETER Input Offset Voltage
CONDITIONS
q
Input Offset Voltage Drift Noninverting Input Current
IIN- en + in - in RIN CIN COUT VINH
Inverting Input Current
q
Input Noise Voltage Density Noninverting Input Noise Current Density Inverting Input Noise Current Density Input Resistance Input Capacitance Output Capacitance Input Voltage Range, High
f = 1kHz, RF = 1k, RG = 10, RS = 0 f = 1kHz f = 1kHz VIN = 3.5V Amplifier Enabled Amplifier Disabled Amplifier Disabled VS = 5V VS = 5V, 0V
q q
2
U
U
W
WW U
W
(Note 1)
Output Short-Circuit Duration (Note 3) ........ Continuous Operating Temperature Range ............... - 40C to 85C Specified Temperature Range (Note 4) .. - 40C to 85C Storage Temperature Range ................ - 65C to 150C Junction Temperature (Note 5) ............................ 150C Lead Temperature (Soldering, 10 sec)................. 300C
TOP VIEW -IN R +IN R *GND -IN G +IN G *GND +IN B -IN B 1 2 3 4 5 6 7 8 B G R 16 EN R 15 OUT R 14 V + 13 EN G 12 OUT G 11 V - 10 OUT B 9 EN B
ORDER PART NUMBER LT1399CGN LT1399CS LT1399HVCS GN PART MARKING 1399
GN PACKAGE S PACKAGE 16-LEAD PLASTIC SSOP 16-LEAD PLASTIC SO
TJMAX = 150C, JA = 120C/W (GN) TJMAX = 150C, JA = 100C/W (S)
MIN
TYP 1.5
MAX 10 12 25 30 50 60
UNITS mV mV V/C A A A A nV/Hz pA/Hz pA/Hz M pF pF pF V V
q q
15 10 10 4.5 6 25 0.3 1 2.0 2.5 8.5 3.5 4.0 4.0
LT1398/LT1399/LT1399HV
(LT1398/LT1399) The q denotes specifications which apply over the specified operating temperature range, otherwise specifications are at TA = 25C. For each amplifier: VCM = 0V, VS = 5V, EN = 0V, pulse tested, unless otherwise noted. (Note 4)
SYMBOL VINL VOUTH PARAMETER Input Voltage Range, Low Maximum Output Voltage Swing, High CONDITIONS VS = 5V VS = 5V, 0V VS = 5V, RL = 100k VS = 5V, RL = 100k VS = 5V, 0V; RL = 100k VS = 5V, RL = 100k VS = 5V, RL = 100k VS = 5V, 0V; RL = 100k VS = 5V, RL = 150 VS = 5V, RL = 150 VS = 5V, 0V; RL = 150 VS = 5V, RL = 150 VS = 5V, RL = 150 VS = 5V, 0V; RL = 150 VCM = 3.5V VCM = 3.5V VCM = 3.5V VS = 2V to 5V, EN = V - VS = 2V to 5V, EN = V -
q q
ELECTRICAL CHARACTERISTICS
MIN - 3.5 3.9 3.7 - 3.9 - 3.7 3.4 3.2 - 3.4 - 3.2 42
TYP - 4.0 1.0 4.2 4.2 - 4.2 0.8 3.6 3.6 - 3.6 0.6
MAX
UNITS V V V V V V V V V V V V V V dB
q
VOUTL
Maximum Output Voltage Swing, Low
q
VOUTH
Maximum Output Voltage Swing, High
q
VOUTL
Maximum Output Voltage Swing, Low
q q q q
CMRR - ICMRR PSRR + IPSRR - IPSRR AV ROL IOUT IS IEN SR tON tOFF tr, tf tPD os tS dG dP
Common Mode Rejection Ratio Inverting Input Current Common Mode Rejection Power Supply Rejection Ratio Noninverting Input Current Power Supply Rejection Inverting Input Current Power Supply Rejection Large-Signal Voltage Gain Transimpedance, VOUT/IIN Maximum Output Current Supply Current per Amplifier Disable Supply Current per Amplifier Enable Pin Current
-
52 10 16 22 2 3 7
A/V A/V dB A/V A/V A/V dB k mA
56
70 1
VS =
2V to 5V, EN = V -
q
2 50 40 65 100 4.6 0.1 30
VOUT = 2V, RL = 150 VOUT = 2V, RL = 150 RL = 0 VOUT = 0V EN Pin Voltage = 4.5V, RL = 150
q q q q
80 6.5 100 110 200 75 100
mA A A A V/s ns ns ns ns % ns % DEG
Slew Rate (Note 6) Turn-On Delay Time (Note 7) Turn-Off Delay Time (Note 7) Small-Signal Rise and Fall Time Propagation Delay Small-Signal Overshoot Settling Time Differential Gain (Note 8) Differential Phase (Note 8)
AV = 10, RL = 150 RF = RG = 324, RL = 100 RF = RG = 324, RL = 100 RF = RG = 324, RL = 100, VOUT = 1VP-P RF = RG = 324, RL = 100, VOUT = 1VP-P RF = RG = 324, RL = 100, VOUT = 1VP-P 0.1%, AV = - 1, RF = RG = 309, RL = 150 RF = RG = 324, RL = 150 RF = RG = 324, RL = 150
500
800 30 40 1.3 2.5 10 25 0.13 0.10
3
LT1398/LT1399/LT1399HV
(LT1399HV) The q denotes specifications which apply over the specified operating temperature range, otherwise specifications are at TA = 25C. For each amplifier: VCM = 0V, VS = 7.5V, EN = 0V, pulse tested, unless otherwise noted. (Note 4)
SYMBOL VOS VOS/T IIN+ IIN- en + in - in RIN CIN COUT VINH VINL VOUTH PARAMETER Input Offset Voltage
q
ELECTRICAL CHARACTERISTICS
CONDITIONS
MIN
TYP 1.5
MAX 10 12 25 30 50 60
UNITS mV mV V/C A A A A nV/Hz pA/Hz pA/Hz M pF pF pF V V V V V V V V V V V V V V V V dB
Input Offset Voltage Drift Noninverting Input Current
q q
15 10 10
Inverting Input Current
q
Input Noise Voltage Density Noninverting Input Noise Current Density Inverting Input Noise Current Density Input Resistance Input Capacitance Output Capacitance Input Voltage Range, High Input Voltage Range, Low Maximum Output Voltage Swing, High
f = 1kHz, RF = 1k, RG = 10, RS = 0, VS = 5V f = 1kHz, VS = 5V f = 1kHz, VS = 5V VIN = 6V Amplifier Enabled Amplifier Disabled Amplifier Disabled VS = 7.5V VS = 7.5V, 0V VS = 7.5V VS = 7.5V, 0V VS = 7.5V, RL = 100k VS = 7.5V, RL = 100k VS = 7.5V, 0V; RL = 100k VS = 7.5V, RL = 100k VS = 7.5V, RL = 100k VS = 7.5V, 0V; RL = 100k VS = 7.5V, RL = 150 VS = 7.5V, RL = 150 VS = 7.5V, 0V; RL = 150 VS = 7.5V, RL = 150 VS = 7.5V, RL = 150 VS = 7.5V, 0V; RL = 150 VCM = 6V VCM = 6V VCM = 6V VS = 2V to 7.5V, EN = V - VS = 2V to 7.5V, EN = V -
q q q q
4.5 6 25 0.3 1 2.0 2.5 8.5 6 -6 6.4 6.1 - 6.4 - 6.1 5.4 5.1 - 5.4 - 5.1 42 6.5 6.5 - 6.5 1.0 6.7 6.7 - 6.7 0.8 5.8 5.8 - 5.8 0.6
q q q q q q
q
VOUTL
Maximum Output Voltage Swing, Low
VOUTH
Maximum Output Voltage Swing, High
VOUTL
Maximum Output Voltage Swing, Low
CMRR - ICMRR PSRR + IPSRR - IPSRR AV ROL IOUT IS IEN
Common Mode Rejection Ratio Inverting Input Current Common Mode Rejection Power Supply Rejection Ratio Noninverting Input Current Power Supply Rejection Inverting Input Current Power Supply Rejection Large-Signal Voltage Gain Transimpedance, VOUT/IIN Maximum Output Current Supply Current per Amplifier Disable Supply Current per Amplifier Enable Pin Current
-
52 10 16 22 2 3 7
A/V A/V dB A/V A/V A/V dB k mA
56
70 1
VS = 2V to 7.5V, EN =
V-
q
2 50 40 65 100 4.6 0.1 30
VOUT = 4.5V, RL = 150 VOUT = 4.5V, RL = 150 RL = 0 VOUT = 0V EN Pin Voltage = 7V, RL = 150
q q q q
80 7 100 110 200
mA A A A
4
LT1398/LT1399/LT1399HV
(LT1399HV) The q denotes specifications which apply over the specified operating temperature range, otherwise specifications are at TA = 25C. For each amplifier: VCM = 0V, VS = 7.5V, EN = 0V, pulse tested, unless otherwise noted. (Note 4)
SYMBOL SR tON tOFF tr, tf tPD os tS dG dP PARAMETER Slew Rate (Note 6) Turn-On Delay Time (Note 7) Turn-Off Delay Time (Note 7) Small-Signal Rise and Fall Time Propagation Delay Small-Signal Overshoot Settling Time Differential Gain (Note 8) Differential Phase (Note 8) CONDITIONS AV = 10, RL = 150, VS = 5V RF = RG = 324, RL = 100, VS = 5V RF = RG = 324, RL = 100, VS = 5V RF = RG = 324, RL = 100, VOUT = 1VP-P, VS = 5V RF = RG = 324, RL = 100, VOUT = 1VP-P, VS = 5V RF = RG = 324, RL = 100, VOUT = 1VP-P, VS = 5V 0.1%, AV = - 1V, RF = RG = 309, RL = 150, VS = 5V RF = RG = 324, RL = 150, VS = 5V RF = RG = 324, RL = 150, VS = 5V MIN 500 TYP 800 30 40 1.3 2.5 10 25 0.13 0.10 75 100 MAX UNITS V/s ns ns ns ns % ns % DEG
ELECTRICAL CHARACTERISTICS
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 0C to 70C and are designed, characterized and expected to meet these extended temperature limits, but are not tested at - 40C and 85C. 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 * 100C/W) LT1399CGN: TJ = TA + (PD * 120C/W)
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.
TYPICAL AC PERFOR A CE
VS (V) 5 5 5 AV 1 2 -1 RL () 100 100 100 RF () 365 324 309 RG () - 324 309 SMALL SIGNAL - 3dB BW (MHz) 300 300 300 SMALL SIGNAL 0.1dB BW (MHz) 150 150 150 SMALL SIGNAL PEAKING (dB) 0.05 0 0
UW
5
LT1398/LT1399/LT1399HV
TYPICAL PERFOR A CE CHARACTERISTICS
Closed-Loop Gain vs Frequency (AV = 1)
4 2 GAIN (dB) GAIN (dB) 0 -2 -4 1M 10M 100M VS = 5V FREQUENCY (Hz) VIN = -10dBm RF = 365 RL = 100 1G
1398/99 G01
6 4 2 1M 10M 100M VS = 5V FREQUENCY (Hz) VIN = -10dBm RF = RG = 324 RL = 100 1G
1398/99 G02
GAIN (dB)
Large-Signal Transient Response (AV = 1)
OUTPUT (1V/DIV)
OUTPUT (1V/DIV)
VS = 5V VIN = 2.5V RF = 365 RL = 100
TIME (5ns/DIV)
1398/99 G04
VS = 5V TIME (5ns/DIV) VIN = 1.25V RF = RG = 324 RL = 100
1398/99 G05
OUTPUT (1V/DIV)
2nd and 3rd Harmonic Distortion vs Frequency
30 TA = 25C 40 RF = RG = 324 RL = 100 50 VS = 5V VOUT = 2VPP 60 70 80 90 100 110 1 10 100 1000 10000 100000 FREQUENCY (kHz)
1398/1399 G07
OUTPUT VOLTAGE (VP-P)
DISTORTION (dB)
HD2
5 4 3 2 1 TA = 25C RF = 324 RL = 100 VS = 5V 10 FREQUENCY (MHz) 100
1398/1399 G08
PSRR (dB)
HD3
6
UW
Closed-Loop Gain vs Frequency (AV = 2)
10 8 4 2 0 -2 -4
Closed-Loop Gain vs Frequency (AV = - 1)
1M 10M 100M VS = 5V FREQUENCY (Hz) VIN = -10dBm RF = RG = 309 RL = 100
1G
1398/99 G03
Large-Signal Transient Response (AV = 2)
Large-Signal Transient Response (AV = - 1)
VS = 5V TIME (5ns/DIV) VIN = 2.5V RF = RG = 309 RL = 100
1398/99 G06
Maximum Undistorted Output Voltage vs Frequency
8 7 AV = +1 6 AV = +2
80 70 60 50 40 30 20 10
PSRR vs Frequency
- PSRR
+ PSRR
0 10k
TA = 25C RF = RG = 324 RL = 100 AV = +2 100k 1M 10M FREQUENCY (Hz) 100M
1398/1399 G09
LT1398/LT1399/LT1399HV
TYPICAL PERFOR A CE CHARACTERISTICS
Input Voltage Noise and Current Noise vs Frequency
1000 INPUT NOISE (nV/Hz OR pA/Hz) 100 RF = RG = 324 RL = 50 AV = +2 VS = 5V
100
OUTPUT IMPEDANCE ()
10
OUTPUT IMPEDANCE (DISABLED) ()
- IN 10 EN +IN
1 10 30 100 300 1k 3k 10k 30k 100k FREQUENCY (Hz)
1398/1399 G10
Maximum Capacitive Load vs Feedback Resistor
1000 OUTPUT SERIES RESISTANCE () 40
100
SUPPLY CURRENT (mA)
CAPACITIVE LOAD (pF)
10 RF = RG AV = +2 VS = 5V PEAKING 5dB 900 1500 2100 2700 FEEDBACK RESISTANCE () 3300
1 300
Output Voltage Swing vs Temperature
5 4
POSITIVE SUPPLY CURRENT PER AMPLIFIER (mA)
OUTPUT VOLTAGE SWING (V)
ENABLE PIN CURRENT (A)
3 2 1 0 -1 -2 -3 -4
RL = 100k
RL = 150
RL = 100k
RL = 150
-5 50 25 0 75 100 -50 -25 AMBIENT TEMPERATURE (C)
UW
1398/1399 G13
1398/1399 G16
Output Impedance vs Frequency
100k
Output Impedance (Disabled) vs Frequency
RF = 365 AV = +1 VS = 5V 10k
1
1k
0.1
0.01 10k
100k
1M 10M FREQUENCY (Hz)
100M
1398/1399 G11
100 100k
1M 10M FREQUENCY (Hz)
100M
1398/1399 G12
Capacitive Load vs Output Series Resistor
RF = RG = 324 VS = 5V OVERSHOOT < 2% 30
6 5 4
Supply Current vs Supply Voltage
EN = V -
EN = 0V 3 2 1
20
10
0 10 100 CAPACITIVE LOAD (pF) 1000
1398/1399 G14
0 0 1 2 7 3 5 6 4 SUPPLY VOLTAGE ( V) 8 9
1398/1399 G15
Enable Pin Current vs Temperature
- 10 - 20 EN = 0V - 30 - 40 EN = -5V - 50 - 60 - 70 - 80 - 50 - 25 VS = 5V 5.00 4.75 4.50 4.25 4.00 3.75 3.50 3.25
Positive Supply Current per Amplifier vs Temperature
VS = 5V EN = - 5V
EN = 0
125
50 100 25 75 0 AMBIENT TEMPERATURE (C)
125
3.00 -50 -25
75 100 0 50 25 AMBIENT TEMPERATURE (C)
125
1398/1399 G17
1398/1399 G18
7
LT1398/LT1399/LT1399HV
TYPICAL PERFOR A CE CHARACTERISTICS
Input Offset Voltage vs Temperature
3.0 2.5
INPUT OFFSET VOLTAGE (mV)
VS = 5V
INPUT BIAS CURRENT (A)
2.0 1.5 1.0 0.5 0 - 0.5 -1.0 - 50 - 25 75 100 50 25 AMBIENT TEMPERATURE (C) 0 125
All Hostile Crosstalk
0 -10 RF = RG = 324 RL = 100 AV = +2 R G B -10 -20
ALL HOSTILE CROSSTALK (dB)
-20 -30 -40 -50 -60 -70 -80 -90
ALL HOSTILE CROSSTALK (dB)
-100 100k
1M
Propagation Delay
INPUT 100mV/DIV OUTPUT 200mV/DIV
AV = +2 TIME (500ps/DIV) RL = 100 RF = RG = 324
8
UW
Input Bias Currents vs Temperature
15 12 IB+ 9 6 3 0 -3 -6 -50 -25 IB- VS = 5V
50 100 25 75 0 AMBIENT TEMPERATURE (C)
125
1398/1399 G19
1398/99 G20
All Hostile Crosstalk (Disabled)
RF = RG = 324 RL = 100 AV = +2 R G B
-30 -40 -50 -60 -70 -80 -90 -100
10M FREQUENCY (Hz)
100M
500M
-110 100k
1M
10M FREQUENCY (Hz)
100M
500M
1398/1399 G21
1398/1399 G24
Rise Time and Overshoot
OS = 10%
VOUT 200mV/DIV
tPD = 2.5ns
1398/1399 G22
tr = 1.3ns AV = +2 TIME (500ps/DIV) RL = 100 RF = RG = 324
1398/1399 G23
LT1398/LT1399/LT1399HV
PIN FUNCTIONS
LT1398
- IN A (Pin 1): Inverting Input of A Channel Amplifier. + IN A (Pin 2): Noninverting Input of A Channel Amplifier. GND (Pins 3, 4, 5, 6): Ground. Not connected internally. + IN B (Pin 7): Noninverting Input of B Channel Amplifier. - IN B (Pin 8): Inverting Input of B Channel Amplifier. EN B (Pin 9): B Channel Enable Pin. Logic low to enable. OUT B (Pin 10): B Channel Output. V - (Pin 11): Negative Supply Voltage, Usually - 5V. GND (Pins 12, 13): Ground. Not connected internally. V + (Pin 14): Positive Supply Voltage, Usually 5V. OUT A (Pin 15): A Channel Output. EN A (Pin 16): A Channel Enable Pin. Logic low to enable.
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.
U
W
U
U
UO
U
U
LT1399, LT1399HV
- IN R (Pin 1): Inverting Input of R Channel Amplifier. + IN R (Pin 2): Noninverting Input of R Channel Amplifier. GND (Pin 3): Ground. Not connected internally. - IN G (Pin 4): Inverting Input of G Channel Amplifier. + IN G (Pin 5): Noninverting Input of G Channel Amplifier. GND (Pin 6): Ground. Not connected internally. + IN B (Pin 7): Noninverting Input of B Channel Amplifier. - IN B (Pin 8): Inverting Input of B Channel Amplifier. EN B (Pin 9): B Channel Enable Pin. Logic low to enable. OUT B (Pin 10): B Channel Output. V - (Pin 11): Negative Supply Voltage, Usually - 5V. 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.
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 (5 to 35) 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
APPLICATI
Power Supplies
S I FOR ATIO
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 600V per volt of supply mismatch. The inverting bias current will typically change about 2A 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/s 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 324 feedback and gain resistors and 5V supplies, the output slew rate is typically 800V/s. 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
+IS (mA)
10
U
will remain enabled at all times, then the EN pin should be tied to the V - supply. The enable pin current is approximately 30A 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 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 0 1 2 4 3 V + - VEN (V) 5 6 7 V - = - 5V TA = 25C V + = 5V V - = 0V
1398/99 F01
W
U
UO
Figure 1. + IS
vs (V +
- VEN)
OUTPUT
EN VS = 5V VIN = 1V RF = 324 RG = 324 RL = 100
1398/99 F02
Figure 2. Amplifier Enable Time, AV = 2
OUTPUT
EN VS = 5V VIN = 1V RF = 324 RG = 324 RL = 100
1398/99 F03
Figure 3. Amplifier Disable Time, AV = 2
LT1398/LT1399/LT1399HV
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). 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 150. 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 75 while maintaining a gain of 1 at the 75 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.
OUTPUT 200mV/DIV
RL = 150 RF = RG = 324 f = 10MHz
5ns/DIV
1398/99 F04
Figure 4. Square Wave Response
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EN A EN B OUTPUT VS = 5V VINA = VINB = 2VP-P at 3.58MHz 20ns/DIV
1398/99 F05
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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 16.9 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
VS = 5V RF = 324 RG = 162 RS = 16.9 CL = 330pF
20ns/DIV
1398/99 AI06
Figure 6. LT1399/LT1399HV Large-Signal Pulse Response
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LT1398/LT1399/LT1399HV
APPLICATI
VIN
S I FOR ATIO
VOUT
VS = 7.5V RF = 324 RG = 162 RS = 16.9 CL = 330pF
50ns/DIV
1398/99 F07
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 75 coax. It is routed to the noninverting input of LT1398 amplifier A1 and to a 1082 resistor R8. There is also an 80.6 termination
75 SOURCES R R11 80.6 G R12 86.6 B R13 76.8
R8 1082
R9 549 R7 324 R10 2940
B1 1/2 LT1398
ALL RESISTORS 1% VS = 5V
B2 1/2 LT1398
1398/99 F08
Figure 8. Buffered RGB to Color-Difference Matrix
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+
+
-
-
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resistor R11, which yields a 75 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. The B input is similar to the R input. It arrives via 75 coax, and is routed to the noninverting input of LT1398 amplifier B2, and to a 2940 resistor R10. There is also a 76.8 termination resistor R13, which yields a 75 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.
+
A1 1/2 LT1398 R-Y R1 324
A2 1/2 LT1398
+
-
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-
R6 162
R5 324
R2 324
Y R4 324
R3 324 B-Y
LT1398/LT1399/LT1399HV
APPLICATI
S I FOR ATIO
The G input also arrives via 75 coax and adds its contribution to the Y signal via a 549 resistor R9, which is tied to the inverting input of amplifier A2. There is also an 86.6 termination resistor R12, which yields a 75 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. 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 75 signal created using resistor R5 and LT1399 amplifier A1 configured for a gain of +2 via 324 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 B output is also a back-terminated 75 signal created using resistor R16 and amplifier A3 configured for a gain of +2 via 324 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
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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 The back-termination resistor R11 then halves the output of A2 resulting in the G output.
R1 1k Y R2 1k R-Y
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+
A1 1/3 LT1399
R5 75 R R3 324
-
R6 205 R7 1k R8 316 R9 845 B-Y R12 1k R13 1k ALL RESISTORS 1% VS = 5V
R4 324
+
A2 1/3 LT1399
R11 75 G R10 324
-
+
A3 1/3 LT1399
R16 75 B R14 324
-
R15 324
1398/99 F09
Figure 9. Buffered Color-Difference to RGB Matrix
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LT1398/LT1399/LT1399HV
SI PLIFIED SCHE ATIC , each amplifier
V+
EN
14
W
W
+IN
-IN
OUT
V-
1398/99 SS
LT1398/LT1399/LT1399HV PACKAGE DESCRIPTIO U
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) 16 15 14 13 12 11 10 9
0.009 (0.229) REF
0.229 - 0.244 (5.817 - 6.198)
0.150 - 0.157** (3.810 - 3.988)
1 0.015 0.004 x 45 (0.38 0.10) 0.007 - 0.0098 (0.178 - 0.249) 0.016 - 0.050 (0.406 - 1.270) * 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 0 - 8 TYP 0.053 - 0.068 (1.351 - 1.727)
23
4
56
7
8 0.004 - 0.0098 (0.102 - 0.249)
0.008 - 0.012 (0.203 - 0.305)
0.025 (0.635) BSC
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
0.228 - 0.244 (5.791 - 6.197)
0.150 - 0.157** (3.810 - 3.988)
1 0.010 - 0.020 x 45 (0.254 - 0.508) 0.008 - 0.010 (0.203 - 0.254) 0 - 8 TYP 0.053 - 0.069 (1.346 - 1.752)
2
3
4
5
6
7
8
0.004 - 0.010 (0.101 - 0.254)
0.016 - 0.050 0.406 - 1.270 *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
0.014 - 0.019 (0.355 - 0.483)
0.050 (1.270) TYP
S16 0695
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
TYPICAL APPLICATI
Single Supply RGB Video Amplifier 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. Amplifier A1 is used in a positive gain configuration. The feedback resistor R8 is 324. The gain resistor is created from the parallel combination of R6 and R7, giving a Thevenin equivalent 80.4 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
VIN
RELATED PARTS
PART NUMBER LT1203/LT1205 LT1204 LT1227 LT1252/LT1253/LT1254 LT1259/LT1260 LT1675 DESCRIPTION 150MHz Video Multiplexers 4-Input Video MUX with Current Feedback Amplifier 140MHz Current Feedback Amplifier Low Cost Video Amplifiers Dual/Triple Current Feedback Amplifier Triple 2:1 Buffered Video Mulitplexer COMMENTS 2:1 and Dual 2:1 MUXs with 25ns Switch Time Cascadable Enable 64:1 Multiplexing 1100V/s Slew Rate, Shutdown Mode Single, Dual and Quad Current Feedback Amplifiers 130MHz Bandwidth, 0.1dB Flatness > 30MHz 2.5ns Switching Time, 250MHz Bandwidth
16
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 q FAX: (408) 434-0507 q www.linear-tech.com
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input. Assuming a 75 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 714. The combination of these two inputs gives an output at the cathode of D2 of 2 * VIN with no additional DC offset. The 75 back termination resistor R9 halves the signal again such that VOUT equals a buffered version of VIN. It is important to note that the 4.7F 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.
R1 1000 R2 1300 R3 160 R4 75 R5 2.32 R6 107 VS 6V TO 12V C1 4.7F D2 D1 1N4148 1N4148
+
A1 1/3 LT1399
R9 75
VOUT
-
R8 324
1398/99 F10
R7 324
Figure 10. Single Supply RGB Video Amplifier (1 of 3 Channels)
13989f LT/TP 0699 4K * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1998

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