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LT1229/LT1230 Dual and Quad 100MHz Current Feedback Amplifiers
FEATURES
s s s s s s s s s s s
DESCRIPTIO
100MHz Bandwidth 1000V/s Slew Rate Low Cost 30mA Output Drive Current 0.04% Differential Gain 0.1 Differential Phase High Input Impedance: 25M, 3pF Wide Supply Range: 2V to 15V Low Supply Current: 6mA Per Amplifier Inputs Common Mode to Within 1.5V of Supplies Outputs Swing Within 0.8V of Supplies
The LT1229/LT1230 dual and quad 100MHz current feedback amplifiers are designed for maximum performance in small packages. Using industry standard pinouts, the dual is available in the 8-pin miniDIP and the 8-pin SO package while the quad is in the 14-pin DIP and 14-pin SO. The amplifiers are designed to operate on almost any available supply voltage from 4V (2V) to 30V (15V). These current feedback amplifiers have very high input impedance and make excellent buffer amplifiers. They maintain their wide bandwidth for almost all closed-loop voltage gains. The amplifiers drive over 30mA of output current and are optimized to drive low impedance loads, such as cables, with excellent linearity at high frequencies. The LT1229/LT1230 are manufactured on Linear Technology's proprietary complementary bipolar process. For a single amplifier like these see the LT1227 and for better DC accuracy see the LT1223.
APPLICATI
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S
Video Instrumentation Amplifiers Cable Drivers RGB Amplifiers Test Equipment Amplifiers
TYPICAL APPLICATI
Video Loop Through Amplifier
R G1 3.01k R F1 750 R G2 187 R F2 750
10 0
Loop Through Amplifier Frequency Response
NORMAL SIGNAL -10
GAIN (dB)
-
3.01k VIN - 1/2 LT1229
-
3.01k VIN+ 1/2 LT1229 VOUT
-20 -30 -40 -50 -60 10 100 1k 10k 100k 1M 10M 100M
LT1229 * TA02
+
+
1% RESISTORS WORST CASE CMRR = 22dB TYPICALLY = 38dB VOUT = G (VIN+ - VIN -) R F1 = RF2
COMMON-MODE SIGNAL
12.1k
12.1k
BNC INPUTS HIGH INPUT RESISTANCE DOES NOT LOAD CABLE EVEN WHEN POWER IS OFF
R G1 = (G - 1) RF2 R F2 RG2 = G-1 TRIM CMRR WITH RG1
LT1229 * TA01
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FREQUENCY (Hz)
UO
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1
LT1229/LT1230 ABSOLUTE AXI U RATI GS
Storage Temperature Range ................. -65C to 150C Junction Temperature Plastic Package .............................................. 150C Ceramic Package ............................................ 175C Lead Temperature (Soldering, 10 sec.)................. 300C Supply Voltage ...................................................... 18V Input Current ...................................................... 15mA Output Short Circuit Duration (Note 1) ......... Continuous Operating Temperature Range LT1229C, LT1230C ............................... 0C to 70C LT1229M, LT1230M ....................... -55C to 125C
PACKAGE/ORDER I FOR ATIO
TOP VIEW OUT A -IN A +IN A V- 1 2 A 3 4 B 6 5 -IN B +IN B 8 7 V+ OUT B
ORDER PART NUMBER LT1229MJ8 LT1229CJ8 LT1229CN8 LT1229CS8 S8 PART MARKING 1229
N8 PACKAGE J8 PACKAGE 8-LEAD CERAMIC DIP 8-LEAD PLASTIC DIP S8 PACKAGE 8-LEAD PLASTIC SOIC LT1124 * POI01
TJ MAX = 175C, JA = 100C/W (J8) TJ MAX = 150C, JA = 100C/W (N8) TJ MAX = 150C, JA = 150C/W (S8)
Each Amplifier, VCM = 0V, 5V VS = 15V, pulse tested unless otherwise noted.
SYMBOL VOS PARAMETER Input Offset Voltage Input Offset Voltage Drift IIN+ IIN- en +in -in RIN CIN Noninverting Input Current Inverting Input Current Input Noise Voltage Density Noninverting Input Noise Current Density Inverting Input Noise Current Density Input Resistance Input Capacitance Input Voltage Range VS = 15V, TA = 25C
q
ELECTRICAL CHARACTERISTICS
CONDITIONS TA = 25C
q q
TA = 25C
q
TA = 25C
q
f = 1kHz, RF = 1k, RG = 10, RS = 0 f = 1kHz, RF = 1k, RG = 10, RS = 10k f = 1kHz VIN = 13V, VS = 15V VIN = 3V, VS = 5V
q q
VS = 5V, TA = 25C
q
CMRR
Common-Mode Rejection Ratio
VS = 15V, VCM = 13V, TA = 25C VS = 15V, VCM = 12V VS = 5V, VCM = 3V, TA = 25C VS = 5V, VCM = 2V
2
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WW
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TOP VIEW
OUT A
1 2 3 4 5 6 7 B C A D
14 OUT D 13 -IN D 12 +IN D 11 V - 10 +IN C 9 8
-IN C
OUT C
ORDER PART NUMBER LT1230MJ LT1230CJ LT1230CN LT1230CS
-IN A +IN A V+ +IN B -IN B
OUT B
J PACKAGE N PACKAGE 14-LEAD CERAMIC DIP 14-LEAD PLASTIC DIP S PACKAGE 14-LEAD PLASTIC SOIC LT1229 * POI02 TJ MAX = 175C, JA = 80C/W (J) TJ MAX = 150C, JA = 70C/W (N) TJ MAX = 150C, JA = 110C/W (S)
MIN
TYP 3 10 0.3 10 3.2 1.4 32
MAX 10 15 3 10 50 100
UNITS mV mV V/C A A A A nV/Hz pA/Hz pA/Hz M M pF V V V V dB dB dB dB
2 2 13 12 3 2 55 55 55 55
25 25 3 13.5 3.5 69 69
q q
LT1229/LT1230
Each Amplifier, VCM = 0V, 5V VS = 15V, pulse tested unless otherwise noted.
SYMBOL PARAMETER Inverting Input Current Common-Mode Rejection CONDITIONS VS = 15V, VCM = 13V, TA = 25C VS = 15V, VCM = 12V VS = 5V, VCM = 3V, TA = 25C VS = 5V, VCM = 2V VS = 2V to 15V, TA = 25C VS = 3V to 15V VS = 2V to 15V, TA = 25C VS = 3V to 15V VS = 2V to 15V, TA = 25C VS = 3V to 15V VS = 15V, VOUT = 10V, RL = 1k VS = 5V, VOUT = 2V, RL = 150 VS = 15V, VOUT = 10V, RL = 1k VS = 5V, VOUT = 2V, RL = 150 VS = 15V, RL = 400, TA = 25C
q q
ELECTRICAL CHARACTERISTICS
MIN
TYP 2.5 2.5
MAX 10 10 10 10
UNITS A/V A/V A/V A/V dB dB
q q q
PSRR
Power Supply Rejection Ratio Noninverting Input Current Power Supply Rejection Inverting Input Current Power Supply Rejection
60 60
80 10 0.1 50 50 5 5
nA/V nA/V A/V A/V dB dB k k V V V V
q q q q q
AV ROL VOUT
Large-Signal Voltage Gain, (Note 2) Transresistance, VOUT/IIN-, (Note 2) Maximum Output Voltage Swing, (Note 2)
55 55 100 100 12 10 3 2.5 30
65 65 200 200 13.5 3.7 65 6 125 9.5 11
VS = 5V, RL = 150, TA = 25C
q
IOUT IS SR SR tr BW tr
Maximum Output Current Supply Current, (Note 3) Slew Rate, (Notes 4 and 6) Slew Rate Rise Time, (Notes 5 and 6) Small-Signal Bandwidth Small-Signal Rise Time Propagation Delay Small-Signal Overshoot
RL = 0, TA = 25C VOUT = 0V, Each Amplifier, TA = 25C
q
mA mA mA V/s V/s
TA = 25C VS = 15V, RF = 750, RG= 750, RL = 400 TA = 25C VS = 15V, RF = 750, RG= 750, RL = 100 VS = 15V, RF = 750, RG= 750, RL = 100 VS = 15V, RF = 750, RG= 750, RL = 100 VS = 15V, RF = 750, RG= 750, RL = 100 0.1%, VOUT = 10V, RF =1k, RG= 1k, RL =1k VS = 15V, RF = 750, RG= 750, RL = 1k VS = 15V, RF = 750, RG= 750, RL = 1k VS = 15V, RF = 750, RG= 750, RL = 150 VS = 15V, RF = 750, RG= 750, RL = 150
300
700 2500 10 100 3.5 3.5 15 45 0.01 0.01 0.04 0.1 20
ns MHz ns ns % ns % Deg % Deg
ts
Settling Time Differential Gain, (Note 7) Differential Phase, (Note 7) Differential Gain, (Note 7) Differential Phase, (Note 7)
The q denotes specifications which apply over the operating temperature range. Note 1: A heat sink may be required depending on the power supply voltage and how many amplifiers are shorted. Note 2: The power tests done on 15V supplies are done on only one amplifier at a time to prevent excessive junction temperatures when testing at maximum operating temperature. Note 3: The supply current of the LT1229/LT1230 has a negative temperature coefficient. For more information see the application information section. Note 4: Slew rate is measured at 5V on a 10V output signal while operating on 15V supplies with RF = 1k, RG = 110 and RL = 400. The
slew rate is much higher when the input is overdriven and when the amplifier is operated inverting, see the applications section. Note 5: Rise time is measured from 10% to 90% on a 500mV output signal while operating on 15V supplies with RF = 1k, RG = 110 and RL = 100. This condition is not the fastest possible, however, it does guarantee the internal capacitances are correct and it makes automatic testing practical. Note 6: AC parameters are 100% tested on the ceramic and plastic DIP packaged parts (J and N suffix) and are sample tested on every lot of the SO packaged parts (S suffix). Note 7: NTSC composite video with an output level of 2VP.
3
LT1229/LT1230
TYPICAL PERFOR A CE CHARACTERISTICS
Voltage Gain and Phase vs Frequency, Gain = 6dB
8 7 6 GAIN PHASE 0 45 90
-3dB BANDWIDTH (MHz)
VOLTAGE GAIN (dB)
5 4 3 2 1 0 -1 -2 0.1 VS = 15V RL = 100 RF = 750 1 10 100
LT1229 * TPC01
135 180 225
120 100 80 60 40 20 0 0 2 4 6 8 10 12
RF = 500 RF = 750 RF = 1k
-3dB BANDWIDTH (MHz)
FREQUENCY (MHz)
Voltage Gain and Phase vs Frequency, Gain = 20dB
22 21 20
VOLTAGE GAIN (dB)
PHASE
-3dB BANDWIDTH (MHz)
19 18 17 16 15 14 13 12 0.1 VS = 15V RL = 100 RF = 750 1 10 100
LT1229 * TPC04
135 180 225
120 100 80 60 40 20 0 0 2 4 6 8 10 12 14 16 18 RF = 250 RF = 500 RF = 750 RF = 1k RF = 2k
-3dB BANDWIDTH (MHz)
GAIN
FREQUENCY (MHz)
Voltage Gain and Phase vs Frequency, Gain = 40dB
42 41 40 PHASE 0 45 90
-3dB BANDWIDTH (MHz)
39 38 37 36 35 34 33 32 0.1 VS = 15V RL = 100 RF = 750 1 10 100
LT1229 * TPC07
135 180 225
12 10 8 6 4 2 0 0 2 4 6 8 10
-3dB BANDWIDTH (MHz)
GAIN
VOLTAGE GAIN (dB)
FREQUENCY (MHz)
4
UW
- 3dB Bandwidth vs Supply Voltage, Gain = 2, RL = 100
180 160 140 PEAKING 0.5dB PEAKING 5dB 180 160 140 120 100 80 60 40 20 0 14 16 18
- 3dB Bandwidth vs Supply Voltage, Gain = 2, RL = 1k
RF = 500 RF = 750
PHASE SHIFT (DEG)
PHASE SHIFT (DEG)
PEAKING 0.5dB PEAKING 5dB RF = 1k RF = 2k
RF = 2k
0
2
4
6
8
10
12
14
16
18
SUPPLY VOLTAGE (V)
LT1229 * TPC02
SUPPLY VOLTAGE (V)
LT1229 * TPC03
- 3dB Bandwidth vs Supply Voltage, Gain = 10, RL = 100
0 45 90
- 3dB Bandwidth vs Supply Voltage, Gain = 10, RL = 1k
180 160 140 120 100 80 60 40 20 0 0 2 4 6 8 10 12 14 16 18 RF = 2k RF = 250 RF = 500 RF = 750 RF = 1k PEAKING 0.5dB PEAKING 5dB
180 160 140 PEAKING 0.5dB PEAKING 5dB
SUPPLY VOLTAGE (V)
LT1229 * TPC05
SUPPLY VOLTAGE (V)
LT1229 * TPC06
- 3dB Bandwidth vs Supply Voltage, Gain = 100, RL = 100
18 16 14 RF = 500 RF = 1k RF = 2k 18 16 14 12 10 8 6 4 2 0 12 14 16 18
- 3dB Bandwidth vs Supply Voltage, Gain = 100, RL = 1k
RF = 500
PHASE SHIFT (DEG)
RF = 1k RF = 2k
0
2
4
6
8
10
12
14
16
18
SUPPLY VOLTAGE (V)
LT1229 * TPC08
SUPPLY VOLTAGE (V)
LT1229 * TPC09
LT1229/LT1230
TYPICAL PERFOR A CE CHARACTERISTICS
Maximum Capacitance Load vs Feedback Resistor
10000
TOTAL HARMONIC DISTORTION (%)
CAPACITIVE LOAD (pF)
1000
VS = 5V
DISTORTION (dBc)
100
VS = 15V
10 RL = 1k PEAKING 5dB GAIN = 2 1 0 1 2 3
LT1229 * TPC10
FEEDBACK RESISTOR (k)
Input Common-Mode Limit vs Temperature
V+
OUTPUT SATURATION VOLTAGE (V)
-0.5
-0.5 -1.0 RL = 2V VS 18V
COMMON MODE RANGE (V)
-1.0 -1.5 -2.0
V + = 2V TO 18V
OUTPUT SHORT CIRCUIT CURRENT (mA)
2.0 1.5 1.0 0.5 V- - 50 -25 0 25 50 75 100 125 TEMPERATURE (C)
LT1229 * TPC13
V - = -2V TO -18V
Spot Noise Voltage and Current vs Frequency
100
80
SPOT NOISE (nV/Hz OR pA/Hz)
60
POSITIVE 40
OUTPUT IMPEDANCE ()
-in
POWER SUPPLY REJECTION (dB)
10
en +in 1 10
100
1k 10k FREQUENCY (Hz)
UW
LT1229 * TPC16
Total Harmonic Distortion vs Frequency
0.10 VS = 15V RL = 400 RF = RG = 750 -20
2nd and 3rd Harmonic Distortion vs Frequency
VS = 15V VO = 2VP-P RL = 100 RF = 750 AV = 10dB
-30
2ND
-40 3RD -50
0.01
VO = 7VRMS
VO = 1VRMS -60
0.001 10 100 1k FREQUENCY (Hz)
LT1229 * TPC11
10k
100k
-70 1 10 FREQUENCY (MHz)
LT1229 * TPC12
100
Output Saturation Voltage vs Temperature
V+
70
Output Short-Circuit Current vs Junction Temperature
60
50
1.0 0.5 V- -50 -25
40
0
25
50
75
100 125
LT1229 * TPC14
30 -50 -25
0
25
50
75 100 125 150 175
LT1229 * TPC15
TEMPERATURE (C)
TEMPERATURE (C)
Power Supply Rejection vs Frequency
100
VS = 15V RL = 100 RF = RG = 750
Output Impedance vs Frequency
VS = 15V 10
1.0 RF = RG = 2k 0.1 RF = RG = 750
NEGATIVE 20
0.01
100k
0 10k
100k
1M FREQUENCY (Hz)
10M
100M
0.001 10k
100k
1M FREQUENCY (Hz)
10M
100M
LT1229 * TPC17
LT1229 * TPC18
5
LT1229/LT1230
TYPICAL PERFOR A CE CHARACTERISTICS
Settling Time to 10mV vs Output Step
10 8 6
OUTPUT STEP (V)
NONINVERTING
INVERTING
SUPPLY CURRENT (mA)
OUTPUT STEP (V)
4 2 0 -2 -4 -6 -8 -10 0 20 40 60 80 100 SETTLING TIME (ns)
LT1229 * TPC19
VS = 15V RF = RG = 1k
NONINVERTING
INVERTING
SI PLIFIED SCHE ATIC
One Amplifier
V+
+IN
6
UW
Settling Time to 1mV vs Output Step
10 8 6 4 2 0 -2 -4 -6 -8 -10 0 4 8 12 16 20 SETTLING TIME (s)
LT1229 * TPC20
Supply Current vs Supply Voltage
10 9 8
NONINVERTING INVERTING
-55C 25C 125C
7 6 5 4 3 2 175C
VS = 15V RF = RG = 1k
INVERTING NONINVERTING
1 0 0 2 4 6 8 10 12 14 16 18 SUPPLY VOLTAGE (V)
LT1229 * TPC21
W
W
-IN
VOUT
V-
LT1229 * TA03
LT1229/LT1230
APPLICATI
S I FOR ATIO
The LT1229/LT1230 are very fast dual and quad current feedback amplifiers. Because they are current feedback amplifiers, they maintain their wide bandwidth over a wide range of voltage gains. These amplifiers are designed to drive low impedance loads such as cables with excellent linearity at high frequencies. Feedback Resistor Selection The small-signal bandwidth of the LT1229/LT1230 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 load resistor. The characteristic curves of Bandwidth versus Supply Voltage are done with a heavy load (100) and a light load (1k) to show the effect of loading. These graphs also show the family of curves that result from various values of the feedback resistor. These curves use a solid line when the response has less than 0.5dB of peaking and a dashed line when the response has 0.5dB to 5dB of peaking. The curves stop where the response has more than 5dB of peaking.
Small-Signal Rise Time with RF = RG = 750, VS = 15V, and RL = 100
LT1229 * TA04
At a gain of two, on 15V supplies with a 750 feedback resistor, the bandwidth into a light load is over 160MHz without peaking, but into a heavy load the bandwidth reduces to 100MHz. The loading has so much effect because there is a mild resonance in the output stage that enhances the bandwidth at light loads but has its Q reduced by the heavy load. This enhancement is only useful at low gain settings; at a gain of ten it does not boost the bandwidth. At unity gain, the enhancement is so effective the value of the feedback resistor has very little effect. At very high closed-loop gains, the bandwidth is
GAIN (dB)
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limited by the gain bandwidth product of about 1GHz. The curves show that the bandwidth at a closed-loop gain of 100 is 10MHz, only one tenth what it is at a gain of two. Capacitance on the Inverting Input Current feedback amplifiers want 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), but it does not degrade the stability of the amplifier. The amount of capacitance that is necessary to cause peaking is a function of the closed-loop gain taken. The higher the gain, the more capacitance is required to cause peaking. We can add capacitance from the inverting input to ground to increase the bandwidth in high gain applications. For example, in this gain of 100 application, the bandwidth can be increased from 10MHz to 17MHz by adding a 2200pF capacitor.
VIN
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+
1/2 LT1229 VOUT
-
RF 510
CG
RG 5.1
LT1229 * TA05
Boosting Bandwidth of High Gain Amplifier with Capacitance on Inverting Input
49 46 43 40 37 34 31 28 25 22 19 1 10 FREQUENCY (MHz)
LT1229 * TA06
C G = 4700pF C G = 2200pF
CG = 0
100
7
LT1229/LT1230
APPLICATI S I FOR ATIO U
amplifier at 150C is less than 7mA and typically is only 4.5mA. The power in the IC due to the load is a function of the output voltage, the supply voltage and load resistance. The worst case occurs when the output voltage is at half supply, if it can go that far, or its maximum value if it cannot reach half supply. For example, let's calculate the worst case power dissipation in a video cable driver operating on 12V supplies that delivers a maximum of 2V into 150. VO (MAX ) Pd (MAX ) = 2 VS IS (MAX ) + VS - VO (MAX ) RL
Capacitive Loads The LT1229/LT1230 can drive capacitive loads directly when the proper value of feedback resistor is used. The graph Maximum Capacitive Load vs Feedback Resistor should be used to select the appropriate value. The value shown is for 5dB peaking when driving a 1k load at a gain of 2. This is a worst case condition; the amplifier is more stable at higher gains and driving heavier loads. 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, and the disadvantage that the gain is a function of the load resistance. Power Supplies The LT1229/LT1230 amplifiers will operate from single or split supplies from 2V (4V total) to 15V (30V 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 350V per volt of supply mismatch, the inverting bias current changes about 2.5A per volt of supply mismatch. Power Dissipation The LT1229/LT1230 amplifiers combine high speed and large output current drive into very small packages. Because these amplifiers work over a very wide supply range, it is possible to exceed the maximum junction temperature under certain conditions. To ensure that the LT1229 and LT1230 remain within their absolute maximum ratings, we must calculate the worst case power dissipation, define the maximum ambient temperature, select the appropriate package and then calculate the maximum junction temperature. The worst case amplifier power dissipation is the total of the quiescent current times the total power supply voltage plus the power in the IC due to the load. The quiescent supply current of the LT1229/LT1230 has a strong negative temperature coefficient. The supply current of each
8
W
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(
)
2V 150 = 0.168 + 0.133 = 0.301W per Amp Now if that is the dual LT1229, the total power in the package is twice that, or 0.602W. We now must calculate how much the die temperature will rise above the ambient. The total power dissipation times the thermal resistance of the package gives the amount of temperature rise. For the above example, if we use the SO8 surface mount package, the thermal resistance is 150C/W junction to ambient in still air. Pd (MAX ) = 2 x 12 V x 7mA + 12 V - 2 V x
Temperature Rise = Pd (MAX) RJA = 0.602W x 150C/W = 90.3C The maximum junction temperature allowed in the plastic package is 150C. Therefore, the maximum ambient allowed is the maximum junction temperature less the temperature rise. Maximum Ambient = 150C - 90.3C = 59.7C Note that this is less than the maximum of 70C that is specified in the absolute maximum data listing. If we must use this package at the maximum ambient we must lower the supply voltage or reduce the output swing. As a guideline to help in the selection of the LT1229/ LT1230 the following table describes the maximum supply voltage that can be used with each part in cable driving applications.
(
)
LT1229/LT1230
APPLICATI
Assumptions: 1. The maximum ambient is 70C for the commercial parts (C suffix) and 125C for the full temperature parts (M suffix). 2. The load is a double-terminated video cable, 150. 3. The maximum output voltage is 2V (peak or DC). 4. The thermal resistance of each package: J8 is 100C/W N8 is 100C/W S8 is 150C/W J is 80/W N is 70/W
LT1229 * TA07
S I FOR ATIO
S is 110/W Larger feedback resistors will reduce the slew rate as will lower supply voltages, similar to the way the bandwidth is reduced.
Large-Signal Response, AV = 10, RF = 1k, RG = 110
Maximum Supply Voltage for 75 Cable Driving Applications at Maximum Ambient Temperature
PART LT1229MJ8 LT1229CJ8 LT1229CN8 LT1229CS8 LT1230MJ LT1230CJ LT1230CN LT1230CS PACKAGE Ceramic DIP Ceramic DIP Plastic DIP Plastic SO8 Ceramic DIP Ceramic DIP Plastic DIP Plastic SO14 MAX POWER AT TA 0.500W @ 125C 1.050W @ 70C 0.800W @ 70C 0.533W @ 70C 0.625W @ 125C 1.313W @ 70C 1.143W @ 70C 0.727W @ 70C MAX SUPPLY VS < 10.1 VS < 18.0 VS < 15.6 VS < 10.6 VS < 6.6 VS < 13.0 VS < 11.4 VS < 7.6
Slew Rate The slew rate of a current feedback amplifier is not independent of the amplifier gain the way it is in a traditional op amp. This is because the input stage and the output stage both have slew rate limitations. The input stage of the LT1229/LT1230 amplifiers slew at about 100V/s before they become nonlinear. Faster input signals will turn on the normally reverse-biased emitters on the input transistors and enhance the slew rate significantly. This enhanced slew rate can be as much as 2500V/s. The output slew rate is set by the value of the feedback resistors and the internal capacitance. At a gain of ten with a 1k feedback resistor and 15V supplies, the output slew rate is typically 700V/s and - 1000V/s. There is no input stage enhancement because of the high gain.
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Large-Signal Response, AV = 2, RF = RG = 750
LT1229 * TA08
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Settling Time The characteristic curves show that the LT1229/LT1230 amplifiers settle to within 10mV of final value in 40ns to 55ns for any output step up to 10V. The curve of settling to 1mV of final value shows that there is a slower thermal contribution up to 20s. The thermal settling component comes from the output and the input stage. The output contributes just under 1mV per volt of output change and the input contributes 300V per volt of input change. Fortunately, the input thermal tends to cancel the output thermal. For this reason the noninverting gain of two configurations settles faster than the inverting gain of one.
9
LT1229/LT1230
APPLICATI
S I FOR ATIO
Crosstalk and Cascaded Amplifiers The amplifiers in the LT1229/LT1230 do not share any common circuitry. The only thing the amplifiers share is the supplies. As a result, the crosstalk between amplifiers is very low. In a good breadboard or with a good PC board layout the crosstalk from the output of one amplifier to the input of another will be over 100dB down, up to 100kHz and 65dB down at 10MHz. The following curve shows the crosstalk from the output of one amplifier to the input of another.
Amplifier Crosstalk vs Frequency
120
OUTPUT TO INPUT CROSSTALK (dB)
110 100 90 80 70 60 50 10 100 1k 10k 100k
VS = 15V AV = 10 RS = 50 RL = 100
1M
10M 100M
LT1229 * TA12
FREQUENCY (Hz)
TYPICAL APPLICATI
S
(the sync pulses). R4, R5 and R6 set the amplifier up with a gain of two and bias the output so the bottom of the sync pulses are at 1.1V. The maximum input then drives the output to 3.9V.
5V R1 3k 2N3904 R2 2k C1 1F VIN C2 1F C4 1000F VOUT R4 1.5k C3 47F
Single 5V Supply Cable Driver for Composite Video This circuit amplifies standard 1V peak composite video input (1.4VP-P) by two and drives an AC coupled, doubly terminated cable. In order for the output to swing 2.8VP-P on a single 5V supply, it must be biased accurately. The average DC level of the composite input is a function of the luminance signal. This will cause problems if we AC couple the input signal into the amplifier because a rapid change in luminance will drive the output into the rails. To prevent this we must establish the DC level at the input and operate the amplifier with DC gain. The transistor's base is biased by R1 and R2 at 2V. The emitter of the transistor clamps the noninverting input of the amplifier to 1.4V at the most negative part of the input
R3 150k R5 750
1/2 LT1229
-
R6 510
10
+
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The high frequency crosstalk between amplifiers is caused by magnetic coupling between the internal wire bonds that connect the IC chip to the package lead frame. The amount of crosstalk is inversely proportional to the load resistor the amplifier is driving, with no load (just the feedback resistor) the crosstalk improves 18dB. The curve shows the crosstalk of the LT1229 amplifier B output (pin 7) to the input of amplifier A. The crosstalk from amplifier A's output (pin 1) to amplifier B is about 10dB better. The crosstalk between all of the LT1230 amplifiers is as shown. The LT1230 amplifiers that are separated by the supplies are a few dB better. When cascading amplifiers the crosstalk will limit the amount of high frequency gain that is available because the crosstalk signal is out of phase with the input signal. This will often show up as unusual frequency response. For example: cascading the two amplifiers in the LT1229, each set up with 20dB of gain and a -3dB bandwidth of 65MHz into 100 will result in 40dB of gain, BUT the response will start to drop at about 10MHz and then flatten out from 20MHz to 30MHz at about 0.5dB down. This is due to the crosstalk back to the input of the first amplifier. For best results when cascading amplifiers use the LT1229 and drive amplifier B and follow it with amplifier A.
+ +
R7 75 R8 10k
LT1229 * TA11
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LT1229/LT1230
TYPICAL APPLICATI UO
5V 4.7F
S
Single Supply AC Coupled Amplifiers Inverting
5V 4.7F
Noninverting
10k
0.1F VIN
10k
+
+
10k 1/2 LT1229 VOUT
0.1F
10k
1/2 LT1229
-
4.7F
-
4.7F
RS 51 510
51
510
VIN 510 10 RS + 51 BW = 600Hz TO 50MHz AV =
AV = 11 BW = 600Hz TO 50MHz
LT1229 * TA09
PACKAGE DESCRIPTIO
0.290 - 0.320 (7.366 - 8.128)
Dimensions in inches (millimeters) unless otherwise noted.
0.405 (10.287) MAX 8 7 6 5
0.200 (5.080) MAX 0.015 - 0.060 (0.381 - 1.524)
0.005 (0.127) MIN
J8 Package 8-Lead Ceramic DIP
0.008 - 0.018 (0.203 - 0.460) 0.385 0.025 (9.779 0.635) 0 - 15 0.038 - 0.068 (0.965 - 1.727) 0.014 - 0.026 (0.360 - 0.660)
0.025 (0.635) RAD TYP 1 2 3
0.125 3.175 0.100 0.010 MIN (2.540 0.254)
0.055 (1.397) MAX
0.300 - 0.320 (7.620 - 8.128)
0.045 - 0.065 (1.143 - 1.651)
0.130 0.005 (3.302 0.127)
0.400 (10.160) MAX 8 7 6 5
N8 Package 8-Lead Plastic DIP
0.009 - 0.015 (0.229 - 0.381)
0.065 (1.651) TYP 0.125 (3.175) MIN 0.020 (0.508) MIN
(
+0.025 0.325 -0.015 +0.635 8.255 -0.381
)
0.045 0.015 (1.143 0.381) 0.100 0.010 (2.540 0.254)
1
2
3
0.018 0.003 (0.457 0.076)
0.189 - 0.197 (4.801 - 5.004) 0.010 - 0.020 x 45 (0.254 - 0.508) 0.053 - 0.069 (1.346 - 1.752) 0.004 - 0.010 (0.101 - 0.254) 0.228 - 0.244 (5.791 - 6.197) 0.150 - 0.157 (3.810 - 3.988) 8 7 6 5
S8 Package 8-Lead Plastic SOIC
0- 8 TYP
0.008 - 0.010 (0.203 - 0.254) 0.016 - 0.050 0.406 - 1.270
0.014 - 0.019 (0.355 - 0.483)
0.050 (1.270) BSC
1
2
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.
+
VOUT
U
+
+
+
LT1229 * TA10
0.220 - 0.310 (5.588 - 7.874)
4
J8 0392
0.250 0.010 (6.350 0.254)
4
N8 0392
3
4
SO8 0392
11
LT1229/LT1230
PACKAGE DESCRIPTIO
0.290 - 0.320 (7.366 - 8.128)
0.008 - 0.018 (0.203 - 0.460) 0.385 0.025 (9.779 0.635)
0 - 15 1 0.038 - 0.068 (0.965 - 1.727) 0.014 - 0.026 (0.360 - 0.660) 0.100 0.010 (2.540 0.254) 0.125 (3.175) MIN 0.098 (2.489) MAX 2 3 4 5 6 7
0.300 - 0.325 (7.620 - 8.255)
0.015 (0.380) MIN 0.130 0.005 (3.302 0.127)
0.009 - 0.015 (0.229 - 0.381) +0.025 0.325 -0.015 +0.635 8.255 -0.381
(
)
0.075 0.015 (1.905 0.381)
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) 0.004 - 0.010 (0.101 - 0.254) 0.228 - 0.244 (5.791 - 6.197)
0 - 8 TYP
0.016 - 0.050 0.406 - 1.270
0.014 - 0.019 (0.355 - 0.483)
12
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7487
(408) 432-1900 q FAX: (408) 434-0507 q TELEX: 499-3977
U
Dimensions in inches (millimeters) unless otherwise noted. J Package 14-Lead Ceramic DIP
0.200 (5.080) MAX 0.015 - 0.060 (0.381 - 1.524) 0.005 (0.127) MIN 0.785 (19.939) MAX 14 13 12 11 10 9 8
0.025 (0.635) RAD TYP
0.220 - 0.310 (5.588 - 7.874)
J14 0392
N Package 14-Lead Plastic DIP
0.065 (1.651) TYP 14 13 12 0.770 (19.558) MAX 11 10 9 8
0.045 - 0.065 (1.143 - 1.651)
0.260 0.010 (6.604 0.254)
0.018 0.003 (0.457 0.076) 0.100 0.010 (2.540 0.254)
1 0.125 (3.175) MIN
2
3
4
5
6
7
N14 0392
S Package 14-Lead Plastic SOIC
0.337 - 0.344 (8.560 - 8.738) 14 13 12 11 10 9 8
0.050 (1.270) TYP
0.150 - 0.157 (3.810 - 3.988)
1
2
3
4
5
6
7
SO14 0392
LT/GP 1092 5K REV A
(c) LINEAR TECHNOLOGY CORPORATION 1992

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