LT1223MJ8#TRPBF [Linear]
IC 1 CHANNEL, VIDEO AMPLIFIER, CDIP8, 0.300 INCH, LEAD FREE, HERMETIC SEALED, CERAMIC, DIP-8, Audio/Video Amplifier;
| 型号： | LT1223MJ8#TRPBF |
| 厂家： | 
Linear |
| 描述： | IC 1 CHANNEL, VIDEO AMPLIFIER, CDIP8, 0.300 INCH, LEAD FREE, HERMETIC SEALED, CERAMIC, DIP-8, Audio/Video Amplifier 放大器 CD |
| 文件： | 总16页 (文件大小：252K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LT1223
100MHz Current
Feedback Amplifier
U
DESCRIPTIO
FEATURES
■
100MHz Bandwidth at AV = 1
The LT®1223 is a 100MHz current feedback amplifier with
very good DC characteristics. The LT1223’s high slew
rate,1000V/µs,widesupplyrange,±15V,andlargeoutput
drive, ±50mA, make it ideal for driving analog signals over
double-terminated cables. The current feedback amplifier
hashighgainbandwidthathighgains,unlikeconventional
op amps.
■
1000V/µs Slew Rate
■
Wide Supply Range: ±5V to ±15V
■
1mV Input Offset Voltage
■
1µA Input Bias Current
■
5MΩ Input Resistance
■
75ns Settling Time to 0.1%
■
50mA Output Current
6mA Quiescent Current
The LT1223 comes in the industry standard pinout and
can upgrade the performance of many older products.
■
■
Available in 8-LeUad Plastic DIP and SO Packages
The LT1223 is manufactured on Linear Technology’s
proprietary complementary bipolar process.
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
APPLICATIO S
■
Video Amplifiers
Buffers
IF and RF Amplification
Cable Drivers
■
■
■
■
8-, 10-, 12-Bit Data Acquisition Systems
U
TYPICAL APPLICATIO
Video Cable Driver
Voltage Gain vs Frequency
60
100MHz GAIN
BANDWIDTH
+
+
V
50
40
IN
75Ω
–
R
G
R
G
R
G
R
G
R
G
= 10
= 33
= 110
= 470
= ∞
1k
LT1223
RG
–
30
75Ω
CABLE
R
F
20
1k
10
V
OUT
0
R
G
1k
75Ω
–10
–20
100k
1M
10M
FREQUENCY (Hz)
100M
1G
R
R
F
A
= 1 +
V
G
LT1223 • TPC01
AT AMPLIFIER OUTPUT
6dB LESS AT V
OUT
LT1223 • TA02
1223fb
1
LT1223
W W U W
W U
ABSOLUTE AXI U RATI GS
/O
PACKAGE RDER I FOR ATIO
(Note 1)
TOP VIEW
ORDER PART
NUMBER
Supply Voltage ...................................................... ±18V
Differential Input Voltage ......................................... ±5V
Input Voltage ............................ Equal to Supply Voltage
Output Short Circuit Duration (Note 2) .........Continuous
Operating Temperature Range
LT1223M (OBSOLETE) .............. –55°C to 125°C
LT1223C................................................ 0°C to 70°C
Storage Temperature Range ..................–65°C to 150°C
Junction Temperature Plastic Package........... 150°C
Junction Temperature Ceramic Package
NULL
–IN
1
2
3
4
SHUTDOWN
8
7
6
5
+
V
LT1223CN8
LT1223CS8
+IN
OUT
–
V
NULL
S8 PART MARKING
1223
N8 PACKAGE
S8 PACKAGE
8-LEAD PLASTIC DIP 8-LEAD PLASTIC SO
TJ MAX = 150°C, θJA = 100°C/W(N8)
TJ MAX = 150°C, θJA = 150°C/W(S8)
J8 PACKAGE
8-LEAD CERAMIC DIP
= 175°C, θ = 100°CW (J8)
JA
LT1223CJ8
LT1223MJ8
T
JMAX
OBSOLETE PACKAGE
(OBSOLETE) ..................................... 175°C
Lead Temperature (Soldering, 10 sec.)................. 300°C
Consider the N8 or S8 for Alternative Source
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS V = ± 15V, T = 25°C, unless otherwise noted.
S
A
LT1223M/C
TYP
SYMBOL
PARAMETER
CONDITIONS
MIN
MAX
±3
UNITS
mV
V
Input Offset Voltage
V
V
V
= 0V
= 0V
= 0V
± 1
± 1
± 1
3.3
2.2
10
OS
CM
CM
CM
I +
IN
Noninverting Input Current
Inverting Input Current
±3
µA
I –
IN
±3
µA
e
Input Noise Voltage Density
Input Noise Current Density
Input Resistance
f = 1kHz, R = 1k, R = 10Ω
nV/√Hz
pA/√Hz
MΩ
pF
n
F
G
i
f = 1kHz, R = 1k, R = 10Ω
F G
n
R
V
= ±10V
1
IN
IN
IN
C
Input Capacitance
1.5
± 12
63
Input Voltage Range
± 10
V
CMRR
PSRR
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
V
V
= ±10V
= ±10V
56
dB
CM
CM
30
100
nA/V
dB
V = ±4.5V to ±18V
S
68
80
V = ±4.5V to ±18V
S
12
100
500
nA/V
nA/V
dB
V = ±4.5V to ±18V
S
60
A
R
LOAD
R
LOAD
R
LOAD
R
LOAD
= 400Ω, V
= 400Ω, V
= 200Ω
= ±10V
= ±10V
70
1.5
± 10
50
89
V
OUT
OUT
R
Transresistance, ∆V /∆I –
5
MΩ
V
OL
OUT
OUT
OUT IN
V
Maximum Output Voltage Swing
Maximum Output Current
Slew Rate
± 12
60
I
= 200Ω
mA
SR
R = 1.5k, R = 1.5k (Note 3)
800
1300
100
V/µs
MHz
F
G
BW
Bandwidth
R = 1k, R = 1k, V
= 100mV
OUT
F
G
1223fb
2
LT1223
ELECTRICAL CHARACTERISTICS V = ± 15V, T = 25°C, unless otherwise noted.
S
A
LT1223M/C
TYP
SYMBOL
PARAMETER
CONDITIONS
MIN
MAX
UNITS
ns
t
t
Rise Time
R = 1.5k, R = 1.5k, V
= 1V
= 1V
= 1V
6.0
6.0
5
r
F
G
OUT
OUT
OUT
Propagation Delay
Overshoot
R = 1.5k, R = 1.5k, V
ns
PD
F
G
R = 1.5k, R = 1.5k, V
%
F
G
t
Settling Time, 0.1%
Differential Gain
R = 1k, R = 1k, V = 10V
OUT
75
0.02
0.12
35
6
ns
s
F
G
R = 1k, R = 1k, R = 150Ω
%
F
G
L
Differential Phase
Open-Loop Output Resistance
Supply Current
R = 1k, R = 1k, R = 150Ω
Deg
Ω
F
G
L
R
V
V
= 0, I
= 0
OUT
OUT
OUT
I
= 0V
IN
10
4
mA
mA
S
Supply Current, Shutdown
Pin 8 Current = 200µA
2
The
CM
●
denotes the specifications which apply over the full operating temperature range, otherwise specifications are at V = ± 15V,
S
V
= 0V, 0°C ≤ T ≤ 70°C, unless otherwise noted.
A
LT1223C
TYP
SYMBOL
PARAMETER
CONDITIONS
MIN
MAX
±3
UNITS
mV
µA
V
Input Offset Voltage
V
V
V
V
= 0V
= 0V
= 0V
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
±1
±1
±1
10
±12
63
30
80
12
60
89
5
OS
CM
CM
CM
I +
IN
Noninverting Input Current
±3
I –
IN
Inverting Input Current
±3
µA
R
IN
Input Resistance
= ±10V
1
MΩ
V
IN
Input Voltage Range
± 10
56
CMRR
PSRR
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
V
V
= ±10V
= ±10V
dB
CM
CM
100
nA/V
dB
V = ±4.5V to ±18V
S
68
V = ±4.5V to ±18V
S
100
500
nA/V
nA/V
dB
V = ±4.5V to ±18V
S
A
R
LOAD
R
LOAD
R
LOAD
R
LOAD
= 400Ω, V
= 400Ω, V
= 200Ω
= ±10V
= ±10V
70
1.5
± 10
50
V
OUT
OUT
R
Transresistance, ∆V /∆I –
MΩ
V
OL
OUT
OUT
S
OUT IN
V
Maximum Output Voltage Swing
Maximum Output Current
Supply Current
± 12
60
6
I
I
= 200Ω
mA
mA
mA
V
= 0V
10
4
IN
Supply Current, Shutdown
Pin 8 Current = 200µA
2
1223fb
3
LT1223
ELECTRICAL CHARACTERISTICS The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at V = ± 15V, V = 0V, –55°C ≤ T ≤ 125°C, unless otherwise noted.
S
CM
A
LT1223M
TYP
SYMBOL
PARAMETER
CONDITIONS
MIN
MAX
±5
UNITS
mV
µA
V
Input Offset Voltage
Noninverting Input Current
Inverting Input Current
Input Resistance
V
V
V
V
= 0V
= 0V
= 0V
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
± 1
± 1
± 1
10
± 12
63
30
80
12
60
89
5
OS
+
CM
CM
CM
I
I
±5
IN
–
±10
µA
IN
R
IN
= ±10V
1
MΩ
V
IN
Input Voltage Range
Common Mode Rejection Ratio
± 10
56
CMRR
PSRR
V
V
= ±10V
= ±10V
dB
CM
CM
Inverting Input Current Common Mode Rejection
Power Supply Rejection Ratio
100
nA/V
dB
V = ±4.5V to ±15V
S
68
Noninverting Input Current Power Supply Rejection
Inverting Input Current Power Supply Rejection
Large-Signal Voltage Gain
V = ±4.5V to ±15V
S
200
500
nA/V
nA/V
dB
V = ±4.5V to ±15V
S
A
R
LOAD
R
LOAD
R
LOAD
R
LOAD
= 400Ω, V
= 400Ω, V
= 200Ω
= ±10V
= ±10V
70
1.5
±7
35
V
OUT
OUT
R
Transresistance, ∆V /∆I –
MΩ
V
OL
OUT
OUT
S
OUT IN
V
Maximum Output Voltage Swing
Maximum Output Current
Supply Current
± 12
60
6
I
I
= 200Ω
mA
mA
mA
V
= 0V
10
4
IN
Supply Current, Shutdown
Pin 8 Current = 200µA
2
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: A heat sink may be required.
Note 3: Noninverting operation, V
= ±10V, measured at ±5V.
OUT
1223fb
4
LT1223
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Supply Current vs Supply Voltage,
IN
Supply Current vs Supply Voltage
(Shutdown)
Output Short Circuit-Current vs
Temperature
V
= 0 (Operating)
10
8
4
3
2
1
0
100
90
80
70
60
50
40
PIN 8 = 0V
125°C
25°C
25°C
6
125°C
–55°C
4
–55°C
30
20
2
0
10
0
0
2
4
6
8
10 12 14 16 18 20
0
2
4
6
8
10 12 14 16 18 20
–50 –25
0
25
CASE TEMPERATURE (°C)
LT1223 • TPC04
50
75 100 125
SUPPLY VOLTAGE (±V)
SUPPLY VOLTAGE (±V)
LT1223 • TPC02
LT1223 • TPC03
Input Common Mode Limit vs
Temperature
+I vs Common Mode Voltage
–I vs Common Mode Voltage
B
B
+
5
4
V
10
8
V
= ±15V
V
= 15V
S
S
–1
–2
–3
–4
4
125°C
V
= 15V
3
2
1
6
4
2
S
–55°C
25°C
V = 5V
S
–55°C
25°C
0
0
125°C
–1
–2
3
–2
–3
–4
–5
–4
–6
2
V = ±15V
S
V = ±5V
S
1
–8
–
V
–10
–50 –25
0
25
50
75 100 125
–15 –10
–5
0
5
10
15
–15 –10
–5
0
5
10
15
TEMPERATURE (°C)
COMMON MODE VOLTAGE (V)
COMMON MODE VOLTAGE (V)
LT1223 • TPC05
LT1223 • TPC06
LT1223 ∑ TPC07
Output Voltage Swing vs
Load Resistor
Output Voltage Swing vs
Supply Voltage
V
vs Common Mode Voltage
OS
20
15
20
15
20
15
V
= ±15V
±
15V
V
=
S
S
125°C
125°C
10
5
10
5
25°C, –55°C
10
–55°C
25°C
5
125°C
0
0
0
25°C
125°C
–5
–5
25°C
–5
–10
–15
–20
–55°C
–10
–15
–20
–10
–15
–20
25°C, –55°C
125°C
–55°C
–15 –10
–5
0
5
10
15
100
1000
LOAD RESISTOR (Ω)
10000
0
2
4
6
8
10 12 14 16 18 20
COMMON MODE VOLTAGE (V)
SUPPLY VOLTAGE (±V)
LT1223 • TPC10
LT1223 • TPC08
LT1223 • TPC09
1223fb
5
LT1223
TYPICAL PERFOR A CE CHARACTERISTICS
U W
–3dB Bandwidth vs
Feedback Resistor
–3dB Bandwidth vs
Supply Voltage
Minimum Feedback Resistor vs
Voltage Gain
100
90
80
70
60
50
40
1000
900
800
700
600
500
400
300
200
100
100
90
80
70
60
50
40
±
R
A
R
= R
= 2
= 100
= 25°C
V
=
15V
A
R
= 2; R = R
F
F
V
L
G
S
L
G
S
V
L
R
= 100
Ω
±
15V
= 100 ; V
=
Ω
NO CAPACITIVE LOAD
T
A
R
= 750
F
R
= 1k
F
0dB PEAKING
2dB PEAKING
R
= 1.5k
F
30
20
30
20
R
= 2k
F
10
0
10
0
0
1
2
3
0
10
20
30
40
50
60
0
5
10
15
FEEDBACK RESISTOR (kΩ)
VOLTAGE GAIN (V/V)
SUPPLY VOLTAGE (±V)
LT1223 • TPC11
LT1223 • TPC13
LT1223 • TPC12
Maximum Capacitive Load vs
Feedback Resistor
Open-Loop Voltage Gain vs
Load Resistor
Transimpedance vs Load Resistor
10
9
100
90
10k
1k
25°C
A
R
= 2; R = R
V = ± 15V
S
V = 10V
±
O
F
G
=
V
L
±
= 100; V
15V
S
PEAKING < 5dB
8
7
6
5
4
3
2
1
0
–55°C
80
25°C
125°C
–55°C
70
60
125°C
100
10
50
40
V = ±15V
O
S
V = ± 10V
100
1000
10000
100
1000
10000
0
1
2
3
FEEDBACK RESISTOR (kΩ)
LOAD RESISTOR (Ω)
LOAD RESISTOR (Ω)
LT1223 • TPC16
LT1223 • TPC15
LT1223 • TPC14
Spot Noise Voltage and Current vs
Frequency
Power Supply Rejection vs
Frequency
Output Impedance vs Frequency
1000
100
10
80
60
40
100
10
1
V
= ±15V
S
F
V
= ±15V
S
R = 1k
POSITIVE
–i
n
R
= R = 3k
G
F
NEGATIVE
R
= R = 1k
G
e
F
n
20
0
0.1
+i
n
1
0.01
10
100
1k
10k
10k
100k
1M
10M
100M
10k
100k
1M
10M
100M
FREQUENCY (Hz)
FREQUENCY (Hz)
FREQUENCY (Hz)
LT1223 • TPC18
LT1223 • TPC17
LT1223 • TPC19
1223fb
6
LT1223
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Voltage Gain and Phase vs
Frequency
Total Harmonic Distortion vs
Frequency
2nd and 3rd Harmonic
Distortion vs Frequency
20
15
225
180
0.1
–20
–30
–40
–50
–60
–70
V
= ±15V
V
= ± 15V
V
= ±15V
S
F
S
S
R = R = 1k
V
= 2V
P-P
V
= 7V
RMS
2ND
3RD
G
O
O
R
R
R
R
A
= 100
= 1k
= 10dB
= 400Ω
= R =1k
G
L
F
L
F
10
5
135
90
GAIN
V
R = 100Ω
R
≥ 1k
L
L
0
–5
45
PHASE
0
0.01
R
≥ 1k
L
–10
–15
–20
–25
–30
–45
–90
–135
–180
–225
R
= 100Ω
L
THD
0.001
1M
10M
100M
1G
10
100
1k
FREQUENCY (Hz)
10k
100k
1
10
100
FREQUENCY (Hz)
FREQUENCY (MHz)
LT1223 • TPC20
LT1223 • TPC21
LT1223 • TPC22
Noninverting Amplifier Settling
Time to 10mV vs Output Step
Noninverting Amplifier Settling
Time to 1mV vs Output Step
Inverting Amplifier Settling
Time vs Output Step
10
8
10
8
10
8
A
R
V
= +1
A
R
V
= –1
A
R
V
= +1
V
F
V
F
V
F
TO 10mV
= 1k
= 1k
= 1k
= ± 15V
= 1k
= ±15V
= 1k
= ±15V
= 1k
S
S
R
S
6
6
6
TO 10mV
TO 1mV
R
R
L
L
L
TO 1mV
4
4
4
2
2
2
0
0
0
–2
–2
–2
–4
–6
–4
–6
–4
–6
TO 1mV
TO 10mV
20
TO 1mV
TO 10mV
60
–8
–8
–8
–10
–10
–10
0
1
2
0
40
60
80
100
0
20
40
80
100
SETTLING TIME (µs)
SETTLING TIME (ns)
SETTLING TIME (ns)
LT1223 • TPC24
LT1223 • TPC25
LT1223 • TPC23
U
W
U U
APPLICATIO S I FOR ATIO
Current Feedback Basics
does in a voltage feedback op amp, the closed-loop
bandwidth does not change. This is because the equiva-
lent gain bandwidth product of the current feedback am-
plifier is set by the Thevenin equivalent resistance at the
inverting input and the internal compensation capacitor.
By keeping RF constant and changing the gain with RG, the
Thevenin resistance changes by the same amount as the
change in gain. As a result, the net closed-loop bandwidth
of the LT1223 remains the same for various closed-loop
gains.
The small-signal bandwidth of the LT1223, like all current
feedback amplifiers, isn’t a straight inverse function of the
closed-loop gain. This is because the feedback resistors
determine the amount of current driving the amplifier’s
internal compensation capacitor. In fact, the amplifier’s
feedback resistor (RF) from output to inverting input
workswithinternaljunctioncapacitancesoftheLT1223to
set the closed-loop bandwidth.
Eventhoughthegainsetresistor(RG)frominvertinginput
to ground works with RF to set the voltage gain just like it
1223fb
7
LT1223
U
W U U
APPLICATIO S I FOR ATIO
The curve on the first page shows the LT1223 voltage gain
versusfrequencywhiledriving100Ω,forfivegainsettings
from 1 to 100. The feedback resistor is a constant 1k and
the gain resistor is varied from infinity to 10Ω. Shown for
comparison is a plot of the fixed 100MHz gain bandwidth
limitation that a voltage feedback amplifier would have. It
is obvious that for gains greater than one, the LT1223
provides 3 to 20 times more bandwidth. It is also evident
thatsecondordereffectsreducethebandwidthsomewhat
at the higher gain settings.
is not necessary to use equal value split supplies, how-
ever, the offset voltage will degrade about 350µV per volt
of mismatch. The internal compensation capacitor de-
creases with increasing supply voltage. The –3dB Band-
width versus Supply Voltage curve shows how this affects
the bandwidth for various feedback resistors. Generally,
the bandwidth at ±5V supplies is about half the value it is
at ±15V supplies for a given feedback resistor.
The LT1223 is very stable even with minimal supply
bypassing, however, the transient response will suffer if
thesupplyrings.Itisrecommendedforgoodslewrateand
settling time that 4.7µF tantalum capacitors be placed
within 0.5 inches of the supply pins.
Feedback Resistor Selection
Because the feedback resistor determines the compensa-
tion of the LT1223, bandwidth and transient response can
be optimized for almost every application. To increase the
bandwidth when using higher gains, the feedback resistor
(and gain resistor) can be reduced from the nominal 1k
value. The Minimum Feedback Resistor versus Voltage
Gain curve shows the values to use for ± 15V supplies.
Larger feedback resistors can also be used to slow down
the LT1223 as shown in the –3dB Bandwidth versus
Feedback Resistor curve.
Input Range
The noninverting input of the LT1223 looks like a 10M
resistor in parallel with a 3pF capacitor until the common
mode range is exceeded. The input impedance drops
somewhat and the input current rises to about 10µA when
the input comes too close to the supplies. Eventually,
when the input exceeds the supply by one diode drop, the
base collector junction of the input transistor forward
biases and the input current rises dramatically. The input
current should be limited to 10mA when exceeding the
supplies. The amplifier will recover quickly when the input
is returned to its normal common mode range unless the
input was over 500mV beyond the supplies, then it will
take an extra 100ns.
Capacitive Loads
The LT1223 can be isolated from capacitive loads with a
small resistor (10Ω to 20Ω) or it can drive the capacitive
load directly if the feedback resistor is increased. Both
techniques lower the amplifier’s bandwidth about the
same amount. The advantage of resistive isolation is that
the bandwidth is only reduced when the capacitive load is
present. The disadvantage of resistor isolation is that
resistive loading causes gain errors. Because the DC
accuracy is not degraded with resistive loading, the de-
sired way of driving capacitive loads, such as flash con-
verters, istoincreasethefeedbackresistor. TheMaximum
Capacitive Load versus Feedback Resistor curve shows
the value of feedback resistor and capacitive load that
gives 5dB of peaking. For less peaking, use a larger
feedback resistor.
Offset Adjust
Output offset voltage is equal to the input offset voltage
times the gain plus the inverting input bias current times
the feedback resistor. For low gain applications (3 or less)
a 10kΩ pot connected to Pins 1 and 5 with wiper to V+ will
trim the inverting input current (±10µA) to null the output;
it does not change the offset voltage very much. If the
LT1223 is used in a high gain application, where input
offset voltage is the dominate error, it can be nulled by
pulling approximately 100µA from Pin 1 or 5. The easy
waytodothisistousea10kΩpotbetweenPin1and5with
a 150k resistor from the wiper to ground for 15V supply
applications. Use a 47k resistor when operating on a 5V
Power Supplies
The LT1223 may be operated with single or split supplies
as low as ±4V (8V total) to as high as ±18V (36V total). It
supply.
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8
LT1223
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APPLICATIO S I FOR ATIO
Output Slew Rate of 500V/µs
Shutdown
Pin 8 activates a shutdown control function. Pulling more
than 200mA from Pin 8 drops the supply current to less
than3mA,andputstheoutputintoahighimpedancestate.
The easy way to force shutdown is to ground Pin 8, using
an open collector (drain) logic stage. An internal resistor
limits current, allowing direct interfacing with no addi-
tional parts. When Pin 8 is open, the LT1223 operates
normally.
Slew Rate
The slew rate of a current feedback amplifier is not inde-
pendent of the amplifier gain configuration the way it is in
a traditional op amp. This is because the input stage and
the output stage both have slew rate limitations. Inverting
amplifiers do not slew the input and are therefore limited
only by the output stage. High gain, noninverting amplifi-
ers are similar. The input stage slew rate of the LT1223 is
about 350V/µs before it becomes nonlinear and is en-
hanced by the normally reverse-biased emitters on the
input transistors. The output slew rate depends on the size
of the feedback resistors. The peak output slew rate is
about 2000V/µs with a 1k feedback resistor and drops
proportionally for larger values. At an output slew rate of
1000V/µs or more, the transistors in the “mirror circuits”
will begin to saturate due to the large feedback currents.
Thiscausestheoutputtohaveslewinducedovershootand
is somewhat unusual looking; it is in no way harmful or
dangerous to the device. The photos show the LT1223 in
a noninverting gain of three (RF = 1k, RG = 500Ω) with a
20V peak-to-peak output slewing at 500V/µs, 1000V/µs
and 2000V/µs.
1223 A01
Output Slew Rate of 1000V/µs
1223 A02
Output Slew Rate at 2000V/µs Shows Aberrations (See Text)
Settling Time
The Inverting Amplifier Settling Time versus Output Step
curve shows that the LT1223 will settle to within 1mV of
final value in less than 100ns for all output changes of 10V
or less. When operated as an inverting amplifier there is
less than 500µV of thermal settling in the amplifier.
However, when operating the LT1223 as a noninverting
amplifier, there is an additional thermal settling compo-
nent that is about 200µV for every volt of input common
mode change. So a noninverting gain of one amplifier will
1223 A03
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9
LT1223
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APPLICATIO S I FOR ATIO
have about 2.5mV thermal tail on a 10V step. Unfortu-
nately, reducing the input signal and increasing the gain
always results in a thermal tail of about the same amount
for a given output step. For this reason we show separate
graphs of 10mV and 1mV non-inverting amplifier settling
times. Just as the bandwidth of the LT1223 is fairly
constant for various closed-loop gains, the settling time
remains constant as well.
Accurate Bandwidth Limiting the LT1223
It is very common to limit the bandwidth of an op amp by
putting a small capacitor in parallel with RF. DO NOT PUT
A SMALL CAPACITOR FROM THE INVERTING INPUT OF
ACURRENTFEEDBACKAMPLIFIERTOANYWHERE ELSE,
ESPECIALLY NOT TO THE OUTPUT. The capacitor on the
inverting input will cause peaking or oscillations. If you
needtolimitthebandwidthofacurrentfeedbackamplifier,
use a resistor and capacitor at the noninverting input (R1
and C1). This technique will also cancel (to a degree) the
peakingcausedbystraycapacitanceattheinvertinginput.
Unfortunately, this will not limit the output noise the way
it does for the op amp.
Adjustable Gain Amplifier
TomakeavariablegainamplifierwiththeLT1223,varythe
value of RG. The implementation of RG can be a pot, a light
controlled resistor, a FET, or any other low capacitance
variable resistor. The value of RF should not be varied to
change the gain. If RF is changed, then the bandwidth will
be reduced at maximum gain and the circuit will oscillate
when RF is very small.
R1
V
+
IN
LT1223
V
OUT
C1
–
V
+
IN
R
F
R1 = 300Ω
C1 = 100pF
BW = 5MHz
LT1223
V
OUT
–
R
G
R
F
LT1223 • TA05
R
G
LT1223 • TA03
Current Feedback Amplifier Integrator
Adjustable Bandwidth Amplifier
Since we remember that the inverting input wants to see
a resistor, we can add one to the standard integrator
circuit. Thisgeneratesanewsummingnodewherewecan
apply capacitive feedback. The LT1223 integrator has
excellentlargesignalcapabilityandaccuratephaseshiftat
high frequencies.
Because the resistance at the inverting input determines
the bandwidth of the LT1223, an adjustable bandwidth
circuit can be made easily. The gain is set as before with
RF and RG; the bandwidth is maximum when the variable
resistor is at a minimum.
V
+
+
IN
LT1223
C1
V
OUT
LT1223
V
OUT
V
V
OUT
1
=
–
–
sC1R1
IN
R
F
5k
1k
R1
R
R
F
G
V
IN
LT1223 • TA06
LT1223 • TA04
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10
LT1223
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APPLICATIO S I FOR ATIO
Summing Amplifier (DC Accurate)
inverting input (A1) senses the shield and the non-invert-
ing input (A2) senses the center conductor. Since this
amplifier does not load the cable (take care to minimize
stray capacitance) and it rejects common mode hum and
noise, several amplifiers can sense the signal with only
one termination at the end of the cable. The design
equations are simple. Just select the gain you need (it
should be two or more) and the value of the feedback
resistor (typically 1k) and calculate RG1 and RG2. The gain
canbetweakedwithRG2 andtheCMRRwithRG1 ifneeded.
The bandwidth of the noninverting input signal is not
reduced by the presence of the other amplifier, however,
the inverting input signal bandwidth is reduced since it
passes two amplifiers. The CMRR is good at high frequen-
cies because the bandwidth of the amplifiers are about the
same even though they do not necessarily operate at the
same gain.
Thesummingamplifieriseasilymadebyaddingadditional
inputs to the basic inverting amplifier configuration. The
LT1223 has no IOS spec because there is no correlation
betweenthetwoinputbiascurrents. Therefore, wewillnot
improve the DC accuracy of the inverting amplifier by
putting in the extra resistor in the noninverting input.
+
LT1223
V
OUT
1
2
R
R
R
G
V
V
–
I1
I2
R
F
G
•
V
V
V
In
•
I1
I2
V
= –R
+
+
•
OUT
F
(
)
n
R
R
R
G1
G2
Gn
G
V
In
LT1223 • TA07
R
G1
1k
R
F1
1k
R
G2
1k
R
F2
1k
Difference Amplifier
The LT1223 difference amplifier delivers excellent
performance if the source impedance is very low. This is
because the common mode input resistance is only equal
to RF + RG.
–
–
A1
LT1223
A2
LT1223
V
OUT
+
+
V
–
V +
IN
IN
+
–
R
(R – 50)
F
G
V
R
= G (V – V )
IN IN
OUT
OPTIONAL TRIM
FOR CMRR
R
F2
G – 1
V1
= R ; R = (G – 1) R ; R
F2 G1 F2 G2
=
F1
100
TRIM GAIN (G) WITH R ; TRIM CMRR WITH R
LT1223 • TA09
G2
G1
+
LT1223
V
OUT
R
Cable Driver
G
V2
–
The cable driver circuit is shown on the front page. When
driving a cable it is important to properly terminate both
ends if even modest high frequency performance is
required. The additional advantage of this is that it isolates
the capacitive load of the cable from the amplifier so it can
operate at maximum bandwidth.
R
F
V
=
(V1 – V2)
R
F
OUT
R
G
LT1223 • TA08
Video Instrumentation Amplifier
This instrumentation amplifier uses two LT1223s to in-
crease the input resistance to well over 1M. This makes an
excellent “loop through” or cable sensing amplifier if the
1223fb
11
LT1223
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TYPICAL APPLICATIO
150mA Output Current Video Amp
75Ω
75Ω
75Ω
75Ω
75Ω
75Ω
75Ω
75Ω
75Ω
75Ω
+
V
+
V
20Ω
BIAS
OUT
V
IN
+
–
IN
2k
LT1223
LT1010
–
–
V
V
2k
R
= 2k TO STABILIZE CIRCUIT
f
DIFFERENTIAL GAIN = 1%
DIFFERENTIAL PHASE = 1°
LT1223 • TA10
W
W
SI PLIFIED SCHE ATIC
7
15k
1
5
BIAS
10k
8
3
6
2
BIAS
4
LT1223 • TA01
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12
LT1223
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PACKAGE DESCRIPTIO
J8 Package
8-Lead CERDIP (Narrow .300 Inch, Hermetic)
(Reference LTC DWG # 05-08-1110)
.405
(10.287)
MAX
CORNER LEADS OPTION
(4 PLCS)
.005
(0.127)
MIN
6
5
4
8
7
2
.023 – .045
(0.584 – 1.143)
HALF LEAD
OPTION
.025
(0.635)
RAD TYP
.220 – .310
(5.588 – 7.874)
.045 – .068
(1.143 – 1.650)
FULL LEAD
OPTION
1
3
.200
.300 BSC
(5.080)
MAX
(7.62 BSC)
.015 – .060
(0.381 – 1.524)
.008 – .018
(0.203 – 0.457)
0° – 15°
.045 – .065
(1.143 – 1.651)
.125
3.175
MIN
NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE
OR TIN PLATE LEADS
.014 – .026
(0.360 – 0.660)
.100
(2.54)
BSC
J8 0801
OBSOLETE PACKAGE
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13
LT1223
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PACKAGE DESCRIPTIO
N8 Package
8-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510)
.400*
(10.160)
MAX
8
7
6
5
4
.255 ± .015*
(6.477 ± 0.381)
1
2
3
.130 ± .005
.300 – .325
.045 – .065
(3.302 ± 0.127)
(1.143 – 1.651)
(7.620 – 8.255)
.065
(1.651)
TYP
.008 – .015
(0.203 – 0.381)
.120
.020
(0.508)
MIN
(3.048)
MIN
+.035
.325
–.015
.018 ± .003
(0.457 ± 0.076)
.100
(2.54)
BSC
+0.889
8.255
(
)
N8 1002
–0.381
NOTE:
INCHES
1. DIMENSIONS ARE
MILLIMETERS
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm)
1223fb
14
LT1223
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PACKAGE DESCRIPTIO
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
.189 – .197
(4.801 – 5.004)
.045 ±.005
.160 ±.005
NOTE 3
.050 BSC
7
5
8
6
.245
MIN
.150 – .157
(3.810 – 3.988)
NOTE 3
.228 – .244
(5.791 – 6.197)
.030 ±.005
TYP
1
3
4
2
RECOMMENDED SOLDER PAD LAYOUT
.010 – .020
(0.254 – 0.508)
× 45°
.053 – .069
(1.346 – 1.752)
.004 – .010
(0.101 – 0.254)
.008 – .010
(0.203 – 0.254)
0°– 8° TYP
.016 – .050
(0.406 – 1.270)
.050
(1.270)
BSC
.014 – .019
(0.355 – 0.483)
TYP
NOTE:
INCHES
1. DIMENSIONS IN
(MILLIMETERS)
2. DRAWING NOT TO SCALE
3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
SO8 0303
1223fb
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 represen-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
15
LT1223
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT1206
250mA/60MHz Current Feedback Amplifier
400MHz Current Feedback Amplifier
900V/µs, Shutdown
LT1395
800V/µs, 4.6mA Supply Current, SOT-23 Package
900V/µs, 7mA Supply Current
C-LoadTM Stable, 200MHz, 700V/µs
LT1497
Dual 125mA, 50MHz Current Feedback Amplifier
LT6210/LT6211
Single/Dual Programmable Supply Current, Rail-to-Rail
Output
C-Load is a trademark of Linear Technology Corporation.
1223fb
LT/LT 0605 REV B • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
16
●
●
© LINEAR TECHNOLOGY CORPORATION 1992
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
相关型号：
LT1224CS8#TR
LT1224 - Very High Speed Operational Amplifier; Package: SO; Pins: 8; Temperature Range: 0°C to 70°C
Linear
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