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Final Electrical Specifications
LT1398/LT1399 Low Cost Dual and Triple 300MHz Current Feedback Amplifiers with Shutdown
December 1998
FEATURES
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DESCRIPTIO
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) 80mA Output Current Low Supply Current: 4.5mA/Amplifier Fast Turn-On Time: 30ns Fast Turn-Off Time: 40ns 16-Pin Narrow SO Package
The LT (R)1399 contains three independent 300MHz current feedback amplifiers, each with a shutdown pin. These amplifiers are designed for excellent linearity while driving cables and other low impedance loads. They are especially suited to RGB video applications. These amplifiers operate on all supplies from a single 4V to 6V and draw only 4.5mA per amplifier when active. The LT1398 is a two amplifier version of the LT1399. When disabled, the LT1398/LT1399 amplifiers draw zero supply current and their outputs become high impedance. These amplifiers turn on in only 30ns and turn off in 40ns, making them ideal in spread spectrum and portable equipment applications. The LT1398/LT1399 amplifiers are manufactured on Linear Technology's proprietary complementary bipolar process. The LT1399 is a pin-for-pin upgrade to the LT1260 optimized for use on 5V supplies.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATI
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RGB Cable Drivers Spread Spectrum Amplifiers MUX Amplifiers Composite Video Cable Drivers Portable Equipment
TYPICAL APPLICATI
A VIN A RG 200 CHANNEL SELECT EN A
3-Input Video MUX Cable Driver
BC
+ -
97.6
Square Wave Response
75 CABLE VOUT
1/3 LT1399 RF 324
VIN B RG 200
+ -
EN B 97.6
75
1/3 LT1399 RF 324
VIN C RG 200
+ -
EN C 97.6
1399 TA01
OUTPUT (200mV/DIV)
1/3 LT1399 RF 324
RL = 100 RF = RG = 340 f = 30MHz
Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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TIME (5ns/DIV)
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1398/99 TA02
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LT1398/LT1399 ABSOLUTE AXI U RATI GS
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
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 + 13 GND* 12 GND* 11 V - 10 OUT B 9 EN B
ORDER PART NUMBER
-IN R
LT1398CS
S PACKAGE 16-LEAD PLASTIC SO TJMAX = 150C, JA = 110C/W
*Ground pins are not internally connected. For best channel isolation, connect to ground. Consult factory for Industrial and Military grade parts.
ELECTRICAL CHARACTERISTICS
TA = 25C, for each amplifier: VCM = 0V, VS = 5V, EN = 0V, pulse tested, unless otherwise noted. (Note 4)
SYMBOL VOS VOS/T IIN+ IIN- en + in - in RIN CIN COUT VINH PARAMETER Input Offset Voltage
q
CONDITIONS
Input Offset Voltage Drift Noninverting Input Current
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
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(Note 1)
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 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 LT1399CS
+IN R *GND -IN G +IN G *GND +IN B -IN B
S PACKAGE 16-LEAD PLASTIC SO TJMAX = 150C, JA = 110C/W
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
ELECTRICAL CHARACTERISTICS
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 VS = 2V to 5V
q q
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 36 - 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 VOUT = 2V, RL = 150 VOUT = 2V, RL = 150 RL = 0 VOUT = 0V EN Pin Voltage = 4.5V, RL = 150
q
2 50 65 100 4.5 0 30
q q q q q
40 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 = - 1V, 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
The q denotes specifications which apply over the specified operating temperature range. 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 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: TJ = TA + (PD * 100C/W)
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LT1398/LT1399
ELECTRICAL CHARACTERISTICS
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
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
GAIN (dB) 1M 10M 100M VS = 5V FREQUENCY (Hz) VIN = -10dBm RF = RG = 324 RL = 100 1G
1398/99 G02
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)
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UW
UW
Closed-Loop Gain vs Frequency (AV = 2)
10 8 6 4 2 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
LT1398/LT1399
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 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. 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
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LT1399
- 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.
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 can drive 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 (10 to 20) 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.
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LT1398/LT1399
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). 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 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 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 of the LT1399, 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 the graph below, +IS 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 will remain enabled at all times, then the EN pin
+IS (mA)
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should be tied to the V - supply. The enable pin current is approximately 30A when activated. If using CMOS opendrain logic, an external 1k pull-up resistor is recommended to ensure that the LT1399 remains disabled in spite of any CMOS drain-leakage currents.
+ IS vs (V + - VEN)
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
1399 AI04
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TA = 25C V + = 5V V - = 0V
V - = - 5V
Amplifier Enable Time, AV = 2
OUTPUT
EN VS = 5V VIN = 1V RF = 324 RG = 324 RL = 100
1398/99 AI01
Amplifier Disable Time, AV = 2
OUTPUT
EN VS = 5V VIN = 1V RF = 324 RG = 324 RL = 100
1398/99 AI02
LT1398/LT1399
APPLICATI
S I FOR ATIO
The enable/disable times are very fast when driven from standard 5V CMOS logic. The amplifier enables in about 30ns (50% point to 50% point) while operating on 5V supplies. Likewise, the disable time is approximately 40ns (50% point to 50% point). 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 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.
SI PLIFIED SCHE ATIC , each amplifier
V+
+IN
EN
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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.
3-Input Video MUX Switching Response (AV = 2)
EN A EN B OUTPUT VS = 5V VINA = VINB = 2VP-P at 3.58MHz
1398/99 AI03
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-IN
OUT
V-
1398/99 SS
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LT1398/LT1399
TYPICAL APPLICATI
VCC 4.7F 0.1F
VEE 4.7F 0.1F
GND
PACKAGE DESCRIPTIO
0.010 - 0.020 x 45 (0.254 - 0.508) 0.008 - 0.010 (0.203 - 0.254) 0.053 - 0.069 (1.346 - 1.752) 0 - 8 TYP
0.016 - 0.050 0.406 - 1.270
0.014 - 0.019 (0.355 - 0.483)
*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
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 MUXes with 25ns Switch Time Cascadable Enable 64:1 Multiplexing 1100V/s Slew Rate, Shutdown Mode Single, Dual and Quad Current Feedback Amplifiers 130MHz Baindwidth, 0.1dB Flatness > 30MHz 2.5ns Switching Time, 250MHz Bandwidth
13989i LT/TP 1298 4K * PRINTED IN USA
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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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PC Board Schematic
75 RIN 75 1 2
+
R 1/3 LT1399 15
75 ROUT RENABLE
-
324
16
324 PIN 14
1k
75 PIN 11 GIN 75
5
+
G 1/3 LT1399 12
75 GOUT GENABLE
4 PINS 3, 6
-
324
13
324
1k
75 BIN 75
7
+
B 1/3 LT1399 10
75 BOUT BENABLE
8
-
324
9
324
1k
1398/99 TA03
Dimensions in inches (millimeters) unless otherwise noted.
S Package 16-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.386 - 0.394* (9.804 - 10.008) 0.004 - 0.010 (0.101 - 0.254) 16 15 14 13 12 11 10 9
0.050 (1.270) BSC
0.228 - 0.244 (5.791 - 6.197)
0.150 - 0.157** (3.810 - 3.988)
S16 1098
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(c) LINEAR TECHNOLOGY CORPORATION 1998

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