LT1229/LT1230
Dual and Quad 100MHz
Current Feedback Amplifiers
EATU
F
■
100MHz Bandwidth
■
1000V/µs Slew Rate
■
Low Cost
■
30mA Output Drive Current
■
0.04% Differential Gain
■
0.1° Differential Phase
■
High Input Impedance: 25MΩ, 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
PPLICATI
A
■
Video Instrumentation Amplifiers
■
Cable Drivers
■
RGB Amplifiers
■
Test Equipment Amplifiers
RE
S
O
U
S
DUESCRIPTIO
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.
O
A
PPLICATITYPICAL
Video Loop Through Amplifier
RG1
3.01k
RF1
750Ω
–
1/2
–
V
LT1229
IN
+
12.1k
HIGH INPUT RESISTANCE DOES NOT LOAD CABLE EVEN
WHEN POWER IS OFF
187Ω
3.01k3.01k
BNC INPUTS
RG2
V
IN
U
+
R
F2
750Ω
–
1/2
LT1229
+
1% RESISTORS
WORST CASE CMRR = 22dB
12.1k
TYPICALLY = 38dB
V
= G (V
OUT
= RF2
R
F1
R
= (G – 1) RF2
G1
=
R
G2
TRIM CMRR WITH R
R
G – 1
Loop Through Amplifier Frequency
Response
10
0
NORMAL SIGNAL
–10
–20
V
OUT
+
–
– V
)
IN
IN
F2
G1
LT1229 • TA01
–30
GAIN (dB)
–40
COMMON-MODE SIGNAL
–50
–60
100 1k 10k 100M
10
100k 1M 10M
FREQUENCY (Hz)
LT1229 • TA02
1
LT1229/LT1230
A
W
O
LUTEXI T
S
A
WUW
ARB
U
G
I
S
Supply Voltage ...................................................... ±18V
Input Current ......................................................±15mA
Output Short Circuit Duration (Note 1) .........Continuous
Operating Temperature Range
LT1229C, LT1230C ............................... 0°C to 70°C
LT1229M, LT1230M....................... –55°C to 125°C
PACKAGE
/
O
RDER I FOR ATIO
WU
U
ORDER PART
TOP VIEW
1
OUT A
2
–IN A
+IN A
V
J8 PACKAGE
8-LEAD CERAMIC DIP
A
3
–
S8 PACKAGE
8-LEAD PLASTIC SOIC
T
= 175°C, θJA = 100°C/W (J8)
J MAX
T
= 150°C, θJA = 100°C/W (N8)
J MAX
= 150°C, θJA = 150°C/W (S8)
T
J MAX
+
8
V
7
OUT B
6
–IN B
B
+IN B
54
N8 PACKAGE
8-LEAD PLASTIC DIP
LT1124 • POI01
NUMBER
LT1229MJ8
LT1229CJ8
LT1229CN8
LT1229CS8
S8 PART MARKING
1229
Storage Temperature Range ................. –65°C to 150°C
Junction Temperature
Plastic Package .............................................. 150°C
Ceramic Package ............................................ 175°C
Lead Temperature (Soldering, 10 sec.)................. 300°C
TOP VIEW
1
OUT A
2
–IN A
+IN A
+IN B
–IN B
OUT B OUT C
J PACKAGE
14-LEAD CERAMIC DIP
A
3
+
4
V
5
B
6
S PACKAGE
14-LEAD PLASTIC SOIC
T
= 175°C, θJA = 80°C/W (J)
J MAX
T
= 150°C, θJA = 70°C/W (N)
J MAX
T
= 150°C, θJA = 110°C/W (S)
J MAX
14
13
D
12
11
10
C
9
87
N PACKAGE
14-LEAD PLASTIC DIP
OUT D
–IN D
+IN D
–
V
+IN C
–IN C
LT1229 • POI02
ORDER PART
NUMBER
LT1230MJ
LT1230CJ
LT1230CN
LT1230CS
LECTRICAL C CHARA TERIST
E
ICS
Each Amplifier, VCM = 0V, ±5V ≤ VS = ±15V, pulse tested unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
OS
+
I
IN
–
I
IN
e
n
+i
n
–in Inverting Input Noise Current Density f = 1kHz 32 pA/√Hz
R
IN
CINInput Capacitance 3pF
CMRR Common-Mode Rejection Ratio VS = ±15V, V
Input Offset Voltage TA = 25°C ±3 ±10 mV
● ±15 mV
Input Offset Voltage Drift ● 10 µV/°C
Noninverting Input Current TA = 25°C ±0.3 ±3 µA
● ±10 µA
Inverting Input Current TA = 25°C ±10 ±50 µA
● ±100 µA
Input Noise Voltage Density f = 1kHz, RF = 1k, RG = 10Ω, RS = 0Ω 3.2 nV/√Hz
Noninverting Input Noise Current Density f = 1kHz, RF = 1k, RG = 10Ω, RS = 10k 1.4 pA/√Hz
Input Resistance V
Input Voltage Range VS = ±15V, TA = 25°C ±13 ±13.5 V
= ±13V, VS = ±15V ● 225 MΩ
IN
V
= ±3V, VS = ±5V ● 225 MΩ
IN
● ±12 V
V
= ±5V, TA = 25°C ±3 ±3.5 V
S
= ±13V, TA = 25°C5569dB
V
= ±15V, V
S
V
= ±5V, V
S
V
= ±5V, V
S
CM
= ±12V ● 55 dB
CM
= ±3V, TA = 25°C5569dB
CM
= ±2V ● 55 dB
CM
● ±2V
2
LT1229/LT1230
LECTRICAL C CHARA TERIST
E
Each Amplifier, VCM = 0V, ±5V ≤ VS = ±15V, pulse tested unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Inverting Input Current VS = ±15V, V
Common-Mode Rejection V
PSRR Power Supply Rejection Ratio VS = ±2V to ±15V, TA = 25°C6080dB
Noninverting Input Current VS = ±2V to ±15V, TA = 25°C1050nA/V
Power Supply Rejection V
Inverting Input Current VS = ±2V to ±15V, TA = 25°C 0.1 5 µA/V
Power Supply Rejection V
A
V
R
OL
V
OUT
I
OUT
I
S
SR Slew Rate, (Notes 4 and 6) TA = 25°C 300 700 V/µs
SR Slew Rate VS = ±15V, RF = 750Ω, RG= 750Ω, RL = 400Ω 2500 V/µs
t
r
BW Small-Signal Bandwidth VS = ±15V, RF = 750Ω, RG= 750Ω, RL = 100Ω 100 MHz
t
r
t
s
Large-Signal Voltage Gain, (Note 2) VS = ±15V, V
Transresistance, ∆V
OUT
/∆I
, (Note 2) VS = ±15V, V
IN–
Maximum Output Voltage Swing, (Note 2) VS = ±15V, RL = 400Ω, TA = 25°C ±12 ±13.5 V
Maximum Output Current RL = 0Ω, TA = 25°C 30 65 125 mA
Supply Current, (Note 3) V
Rise Time, (Notes 5 and 6) TA = 25°C1020ns
Small-Signal Rise Time VS = ±15V, RF = 750Ω, RG= 750Ω, RL = 100Ω 3.5 ns
Propagation Delay VS = ±15V, RF = 750Ω, RG= 750Ω, RL = 100Ω 3.5 ns
Small-Signal Overshoot VS = ±15V, RF = 750Ω, RG= 750Ω, RL = 100Ω 15 %
Settling Time 0.1%, V
Differential Gain, (Note 7) VS = ±15V, RF = 750Ω, RG= 750Ω, RL = 1k 0.01 %
Differential Phase, (Note 7) VS = ±15V, RF = 750Ω, RG= 750Ω, RL = 1k 0.01 Deg
Differential Gain, (Note 7) VS = ±15V, RF = 750Ω, RG= 750Ω, RL = 150Ω 0.04 %
Differential Phase, (Note 7) VS = ±15V, RF = 750Ω, RG= 750Ω, RL = 150Ω 0.1 Deg
ICS
= ±13V, TA = 25°C 2.5 10 µA/V
= ±15V, V
S
= ±5V, V
V
S
= ±5V, V
V
S
V
= ±3V to ±15V ● 60 dB
S
= ±3V to ±15V ● 50 nA/V
S
= ±3V to ±15V ● 5 µA/V
S
= ±5V, V
V
S
= ±5V, V
V
S
= ±5V, RL = 150Ω, TA = 25°C ±3 ±3.7 V
V
S
OUT
CM
= ±12V ● 10 µA/V
CM
= ±3V, TA = 25°C 2.5 10 µA/V
CM
= ±2V ● 10 µA/V
CM
= ±10V, RL = 1k ● 55 65 dB
OUT
= ±2V, RL = 150Ω ● 55 65 dB
OUT
= ±10V, RL = 1k ● 100 200 kΩ
OUT
= ±2V, RL = 150Ω ● 100 200 kΩ
OUT
● ±10 V
● ±2.5 V
= 0V, Each Amplifier, TA = 25°C 6 9.5 mA
● 11 mA
= 10V, RF =1k, RG= 1k, RL =1k 45 ns
OUT
The ● 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 R
= 1k, RG = 110Ω and RL = 400Ω. The
F
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 R
= 1k, RG = 110Ω and RL =
F
100Ω. 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 2V
.
P
3
LT1229/LT1230
SUPPLY VOLTAGE (±V)
2
–3dB BANDWIDTH (MHz)
40
100
120
12 16
LT1229 • TPC06
4068101418
0
20
60
140
160
180
RF = 500Ω
80
PEAKING ≤ 0.5dB
PEAKING ≤ 5dB
RF = 750Ω
RF = 1k
RF = 2k
RF = 250Ω
SUPPLY VOLTAGE (±V)
2
–3dB BANDWIDTH (MHz)
4
10
12
12 16
LT1229 • TPC09
4068101418
0
2
6
14
16
18
RF = 500Ω
8
RF = 1k
RF = 2k
SUPPLY VOLTAGE (±V)
2
–3dB BANDWIDTH (MHz)
40
100
120
12 16
LT1229 • TPC03
4068101418
0
20
60
140
160
180
80
PEAKING ≤ 0.5dB
PEAKING ≤ 5dB
RF = 750Ω
RF = 1k
RF = 2k
RF = 500Ω
UW
Y
PICA
8
7
6
5
4
3
2
VOLTAGE GAIN (dB)
1
0
–1
–2
0.1 10 100
22
21
20
19
18
17
16
VOLTAGE GAIN (dB)
15
14
13
12
0.1 10 100
LPER
F
O
R
AT
CCHARA TERIST
E
C
ICS
Voltage Gain and Phase vs –3dB Bandwidth vs Supply –3dB Bandwidth vs Supply
Frequency, Gain = 6dB Voltage, Gain = 2, RL = 100Ω Voltage, Gain = 2, RL = 1k
PHASE
GAIN
VS = ±15V
= 100Ω
R
L
= 750Ω
R
F
1
FREQUENCY (MHz)
LT1229 • TPC01
0
45
90
PHASE SHIFT (DEG)
135
180
225
180
160
140
120
100
80
60
–3dB BANDWIDTH (MHz)
40
20
0
PEAKING ≤ 0.5dB
PEAKING ≤ 5dB
4068101418
2
SUPPLY VOLTAGE (±V)
RF = 500Ω
RF = 750Ω
RF = 1k
RF = 2k
12 16
LT1229 • TPC02
Voltage Gain and Phase vs –3dB Bandwidth vs Supply –3dB Bandwidth vs Supply
Frequency, Gain = 20dB Voltage, Gain = 10, RL = 100Ω Voltage, Gain = 10, RL = 1k
PHASE
GAIN
VS = ±15V
= 100Ω
R
L
= 750Ω
R
F
1
FREQUENCY (MHz)
LT1229 • TPC04
0
45
90
PHASE SHIFT (DEG)
135
180
225
180
160
140
120
100
80
60
–3dB BANDWIDTH (MHz)
40
20
0
PEAKING ≤ 0.5dB
PEAKING ≤ 5dB
4068101418
2
SUPPLY VOLTAGE (±V)
RF = 250Ω
RF = 500Ω
RF = 750Ω
RF = 1k
RF = 2k
12 16
LT1229 • TPC05
Voltage Gain and Phase vs –3dB Bandwidth vs Supply –3dB Bandwidth vs Supply
Frequency, Gain = 40dB Voltage, Gain = 100, RL = 100Ω Voltage, Gain = 100, RL = 1kΩ
42
41
40
39
38
37
36
VOLTAGE GAIN (dB)
35
34
33
32
0.1 10 100
4
PHASE
GAIN
VS = ±15V
= 100Ω
R
L
= 750Ω
R
F
1
FREQUENCY (MHz)
LT1229 • TPC07
0
45
90
PHASE SHIFT (DEG)
135
180
225
18
16
14
12
10
8
6
–3dB BANDWIDTH (MHz)
4
2
0
4068101418
2
SUPPLY VOLTAGE (±V)
RF = 500Ω
RF = 1k
RF = 2k
12 16
LT1229 • TPC08
LT1229/LT1230
TEMPERATURE (°C)
–25
OUTPUT SHORT CIRCUIT CURRENT (mA)
40
60
100 150
LT1229 • TPC15
0–50 25 50 75 125 175
30
70
50
FREQUENCY (Hz)
OUTPUT IMPEDANCE (Ω)
0.1
100
10k 1M 10M 100M
LT1229 • TPC18
0.001
100k
0.01
10
VS = ±15V
1.0
RF = RG = 2k
RF = RG = 750Ω
UW
Y
PICA
10000
1000
100
CAPACITIVE LOAD (pF)
10
1
+
V
–0.5
–1.0
–1.5
–2.0
2.0
1.5
COMMON MODE RANGE (V)
1.0
0.5
–
V
–50 25 75 125
LPER
F
O
R
AT
CCHARA TERIST
E
C
ICS
Maximum Capacitance Load vs Total Harmonic Distortion vs 2nd and 3rd Harmonic
Feedback Resistor Frequency Distortion vs Frequency
0.10
VS = ±5V
VS = ±15V
RL = 1k
PEAKING ≤ 5dB
GAIN = 2
023
1
FEEDBACK RESISTOR (kΩ)
LT1229 • TPC10
0.01
TOTAL HARMONIC DISTORTION (%)
0.001
VS = ±15V
= 400Ω
R
L
= RG = 750Ω
R
F
VO = 7V
RMS
VO = 1V
RMS
10 1k 10k 100k
100
FREQUENCY (Hz)
LT1229 • TPC11
–20
VS = ±15V
= 2V
V
O
= 100Ω
R
–30
–40
–50
DISTORTION (dBc)
–60
–70
L
= 750Ω
R
F
= 10dB
A
V
1
P-P
10 100
FREQUENCY (MHz)
Input Common-Mode Limit vs Output Saturation Voltage vs Output Short-Circuit Current vs
Temperature Temperature Junction Temperature
+
V
–0.5
V+ = 2V TO 18V
V– = –2V TO –18V
0
–25 50 100
TEMPERATURE (°C)
LT1229 • TPC13
–1.0
RL = ∞
≤ ±18V
±2V ≤ V
S
1.0
0.5
OUTPUT SATURATION VOLTAGE (V)
–
V
–50 25 75 125
0
–25 50 100
TEMPERATURE (°C)
LT1229 • TPC14
2ND
3RD
LT1229 • TPC12
Spot Noise Voltage and Current vs Power Supply Rejection vs Output Impedance vs
Frequency Frequency Frequency
100
–i
n
10
SPOT NOISE (nV/√Hz OR pA/√Hz)
1
10
e
n
+i
n
100 10k
FREQUENCY (Hz)
1k 100k
LT1229 • TPC16
80
VS = ±15V
= 100Ω
R
L
= RG = 750Ω
R
60
40
20
POWER SUPPLY REJECTION (dB)
0
10k 1M 10M 100M
100k
FREQUENCY (Hz)
F
POSITIVE
NEGATIVE
LT1229 • TPC17
5
LT1229/LT1230
SUPPLY VOLTAGE (±V)
SUPPLY CURRENT (mA)
12
LT1229 • TPC21
40816
0
10
5
1
2
3
4
6
7
8
9
2 6 10 14 18
–55°C
25°C
125°C
175°C
UW
LPER
F
O
R
ATYPICA
Settling Time to 10mV vs Settling Time to 1mV vs
Output Step Output Step Supply Current vs Supply Voltage
10
NONINVERTING
8
6
4
2
0
–2
OUTPUT STEP (V)
–4
–6
–8
NONINVERTING
–10
200 40 80 100
SETTLING TIME (ns)
INVERTING
V
= ±15V
S
= RG = 1k
R
F
INVERTING
60
LT1229 • TPC19
CCHARA TERIST
E
C
10
8
6
4
2
0
–2
OUTPUT STEP (V)
–4
–6
–8
–10
NONINVERTING
NONINVERTING
40 8 16 20
ICS
INVERTING
V
S
R
INVERTING
12
SETTLING TIME (µs)
= ±15V
= RG = 1k
F
LT1229 • TPC20
SPL
I
6
E
W
A
TI
C
W
IIFED S
CH
One Amplifier
+IN –IN V
+
V
OUT
–
V
LT1229 • TA03
LT1229/LT1230
PPLICATI
A
U
O
S
I FOR ATIO
WU
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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 (100Ω) 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 = 750Ω, VS = ±15V, and RL = 100Ω
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.
V
IN
+
1/2
LT1229
–
R
510Ω
V
OUT
F
LT1229 • TA04
At a gain of two, on ± 15V supplies with a 750Ω 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
C
Boosting Bandwidth of High Gain Amplifier with
49
46
43
40
37
34
GAIN (dB)
31
28
25
22
19
RG
G
5.1Ω
Capacitance on Inverting Input
CG = 4700pF
= 2200pF
C
G
C
= 0
G
1
10 100
FREQUENCY (MHz)
LT1229 • TA05
LT1229 • TA06
7
LT1229/LT1230
PVIVV
V
R
PVmAVV
V
W per Amp
d MAX S S MAX S O MAX
O MAX
L
d MAX
() () ()
()
()
=+
()
=× × +
()
×
=+=
2
2 12 7 12 2
2
150
0 168 0 133 0 301
–
–
...
Ω
U
O
PPLICATI
A
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 (10Ω to 20Ω) 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 350µV per volt
of supply mismatch, the inverting bias current changes
about 2.5µA per volt of supply mismatch.
S
I FOR ATIO
WU
U
amplifier at 150°C 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 150Ω.
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
150°C/W junction to ambient in still air.
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
Temperature Rise = P
150°C/W = 90.3°C
The maximum junction temperature allowed in the plastic
package is 150°C. Therefore, the maximum ambient allowed is the maximum junction temperature less the
temperature rise.
Maximum Ambient = 150°C – 90.3°C = 59.7°C
Note that this is less than the maximum of 70°C 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.
d (MAX) RθJA
= 0.602W ×
LT1229/LT1230
PPLICATI
A
U
O
S
I FOR ATIO
WU
U
Assumptions:
1. The maximum ambient is 70°C for the commercial
parts (C suffix) and 125°C for the full temperature
parts (M suffix).
2. The load is a double-terminated video cable, 150Ω.
3. The maximum output voltage is 2V (peak or DC).
4. The thermal resistance of each package:
J8 is 100°C/W J is 80°/W
N8 is 100°C/W N is 70°/W
S8 is 150°C/W S is 110°/W
Maximum Supply Voltage for 75Ω Cable Driving Applications at
Maximum Ambient Temperature
PART PACKAGE MAX POWER AT TAMAX SUPPLY
LT1229MJ8 Ceramic DIP 0.500W @ 125°CV
LT1229CJ8 Ceramic DIP 1.050W @ 70°CV
LT1229CN8 Plastic DIP 0.800W @ 70°CV
LT1229CS8 Plastic SO8 0.533W @ 70°CV
< ±10.1
S
< ±18.0
S
< ±15.6
S
< ±10.6
S
Large-Signal Response, AV = 2, RF = RG = 750Ω
LT1229 • TA07
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 = 110Ω
LT1230MJ Ceramic DIP 0.625W @ 125°CV
LT1230CJ Ceramic DIP 1.313W @ 70°CV
LT1230CN Plastic DIP 1.143W @ 70°CV
LT1230CS Plastic SO14 0.727W @ 70°CV
< ±6.6
S
< ±13.0
S
< ±11.4
S
< ±7.6
S
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/µs 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/µs.
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/µs and –1000V/µs. There
is no input stage enhancement because of the high gain.
LT1229 • TA08
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 20µs. 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 300µV 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
LT1229 • TA11
–
+
1/2
LT1229
V
OUT
R3
150k
R2
2k
V
IN
R5
750Ω
C1
1µF
+
R8
10k
R1
3k
C2
1µF
R4
1.5k
+
2N3904
5V
C3
47µF
R6
510Ω
R7
75Ω
C4
1000µF
PPLICATI
A
U
O
S
I FOR ATIO
WU
U
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
110
100
90
80
70
60
OUTPUT TO INPUT CROSSTALK (dB)
50
100 1k 10k 100M
10
FREQUENCY (Hz)
VS = ±15V
= 10
A
V
= 50Ω
R
S
= 100Ω
R
L
100k 1M 10M
LT1229 • TA12
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 100Ω 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.
U
O
PPLICATITYPICAL
Single 5V Supply Cable Driver for Composite Video
This circuit amplifies standard 1V peak composite video
input (1.4V
terminated cable. In order for the output to swing
2.8V
P-P
) by two and drives an AC coupled, doubly
P-P
on a single 5V supply, it must be biased accu-
SA
(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.
rately. 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
10
PPLICATITYPICAL
Noninverting Inverting
5V
0.1µF
V
IN
10k
10k
+
1/2
LT1229
–
4.7µF
+
AV = 11
BW = 600Hz TO 50MHz
510Ω51Ω
PACKAGEDESCRIPTI
O
4.7µF
+
O
U
SA
Single Supply AC Coupled Amplifiers
V
OUT
LT1229 • TA09
V
IN
0.1µF
4.7µF
R
S
+
51Ω
AV = 10
R
BW = 600Hz TO 50MHz
U
Dimensions in inches (millimeters) unless otherwise noted.
10kΩ
10kΩ
510Ω
+ 51Ω
S
LT1229/LT1230
5V
4.7µF
+
+
1/2
LT1229
–
510Ω
V
LT1229 • TA10
OUT
J8 Package
8-Lead Ceramic DIP
N8 Package
8-Lead Plastic DIP
S8 Package
8-Lead Plastic SOIC
0°– 8° TYP
0.290 – 0.320
(7.366 – 8.128)
0.008 – 0.018
(0.203 – 0.460)
0.385 ± 0.025
(9.779 ± 0.635)
0.300 – 0.320
(7.620 – 8.128)
0.009 – 0.015
(0.229 – 0.381)
0.325
8.255
()
0.010 – 0.020
(0.254 – 0.508)
0.016 – 0.050
0.406 – 1.270
+0.025
–0.015
+0.635
–0.381
0° – 15°
× 45°
0.008 – 0.010
(0.203 – 0.254)
0.038 – 0.068
(0.965 – 1.727)
0.014 – 0.026
(0.360 – 0.660)
0.065
(1.651)
TYP
0.045 ± 0.015
(1.143 ± 0.381)
0.100 ± 0.010
(2.540 ± 0.254)
0.045 – 0.065
(1.143 – 1.651)
0.053 – 0.069
(1.346 – 1.752)
0.014 – 0.019
(0.355 – 0.483)
0.015 – 0.060
(0.381 – 1.524)
0.100 ± 0.010
(2.540 ± 0.254)
0.130 ± 0.005
(3.302 ± 0.127)
0.125
(3.175)
MIN
0.018 ± 0.003
(0.457 ± 0.076)
0.004 – 0.010
(0.101 – 0.254)
0.050
(1.270)
BSC
0.405
0.200
(5.080)
MAX
0.125
3.175
MIN
0.020
(0.508)
MIN
0.005
(0.127)
MIN
0.025
(0.635)
RAD TYP
0.055
(1.397)
MAX
0.228 – 0.244
(5.791 – 6.197)
876
1234
(10.287)
87
12
0.400
(10.160)
MAX
0.189 – 0.197
(4.801 – 5.004)
7
8
MAX
5
6
65
3
4
0.250 ± 0.010
(6.350 ± 0.254)
5
0.220 – 0.310
(5.588 – 7.874)
N8 0392
0.150 – 0.157
(3.810 – 3.988)
J8 0392
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.
1
3
2
4
SO8 0392
11
LT1229/LT1230
PACKAGEDESCRIPTI
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°
0.038 – 0.068
(0.965 – 1.727)
U
O
Dimensions in inches (millimeters) unless otherwise noted.
J Package
14-Lead Ceramic DIP
0.005
(0.127)
0.025
(0.635)
RAD TYP
0.098
(2.489)
MAX
MIN
0.014 – 0.026
(0.360 – 0.660)
0.200
(5.080)
MAX
0.015 – 0.060
(0.381 – 1.524)
0.100 ± 0.010
(2.540 ± 0.254)
0.125
(3.175)
MIN
N Package
14-Lead Plastic DIP
14
234
1
0.785
(19.939)
MAX
12
11 891013
0.220 – 0.310
(5.588 – 7.874)
56
7
J14 0392
0.300 – 0.325
(7.620 – 8.255)
0.009 – 0.015
(0.229 – 0.381)
+0.025
0.325
–0.015
+0.635
8.255
()
–0.381
0° – 8° TYP
0.010 – 0.020
(0.254 – 0.508)
0.016 – 0.050
0.406 – 1.270
× 45°
0.008 – 0.010
(0.203 – 0.254)
0.015
(0.380)
MIN
(1.905 ± 0.381)
(1.346 – 1.752)
0.130 ± 0.005
(3.302 ± 0.127)
0.075 ± 0.015
0.053 – 0.069
0.014 – 0.019
(0.355 – 0.483)
0.045 – 0.065
(1.143 – 1.651)
0.018 ± 0.003
(0.457 ± 0.076)
0.100 ± 0.010
(2.540 ± 0.254)
(3.175)
S Package
14-Lead Plastic SOIC
0.004 – 0.010
(0.101 – 0.254)
0.050
(1.270)
TYP
0.065
(1.651)
TYP
0.125
MIN
0.228 – 0.244
(5.791 – 6.197)
0.260 ± 0.010
(6.604 ± 0.254)
14
1
13
2
14
0.337 – 0.344
(8.560 – 8.738)
12
3
2
11 10
4
0.770
(19.558)
MAX
11
1213
31
5
4
9
5
6
8
7
6
0.150 – 0.157
(3.810 – 3.988)
8910
7
N14 0392
SO14 0392
12
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7487
(408) 432-1900
●
FAX
: (408) 434-0507
●
TELEX
: 499-3977
LT/GP 1092 5K REV A
LINEAR TECHNOLOGY CORPORATION 1992
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