LT1812CS8#PBF [Linear]
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| 型号： | LT1812CS8#PBF |
| 厂家： | 
Linear |
| 描述： | 暂无描述 运算放大器 放大器电路 光电二极管 |
| 文件： | 总12页 (文件大小：206K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LT1812
3mA, 100MHz, 750V/µs
Operational Amplifier
with Shutdown
U
FEATURES
DESCRIPTIO
The LT®1812 is a low power, high speed, very high slew
rate operational amplifier with excellent DC performance.
The LT1812 features reduced supply current, lower input
offset voltage, lower input bias current and higher DC gain
than other devices with comparable bandwidth. A power
saving shutdown feature reduces supply current to 50µA.
The circuit topology is a voltage feedback amplifier with
theslewingcharacteristicsofacurrentfeedbackamplifier.
■
100MHz Gain Bandwidth
■
750V/µs Slew Rate
■
3.6mA Maximum Supply Current
50µA Supply Current in Shutdown
8nV/√Hz Input Noise Voltage
Unity-Gain Stable
■
■
■
■
■
■
■
■
■
■
■
1.5mV Maximum Input Offset Voltage
4µA Maximum Input Bias Current
400nA Maximum Input Offset Current
40mA Minimum Output Current, VOUT = ±3V
±3.5V Minimum Input CMR, VS = ±5V
30ns Settling Time to 0.1%, 5V Step
Specified at ±5V, Single 5V Supplies
Operating Temperature Range: –40°C to 85°C
Theoutputdrivesa100Ωloadto±3.5Vwith±5Vsupplies.
Onasingle5Vsupply,theoutputswingsfrom1.1Vto3.9V
witha100Ωloadconnectedto2.5V.Theamplifierisstable
with a 1000pF capacitive load which makes it useful in
buffer and cable driver applications.
The LT1812 is manufactured on Linear Technology’s
advanced low voltage complementary bipolar process.
The dual version is the LT1813. For higher supply voltage
single, dual and quad operational amplifiers with up to
70MHz gain bandwidth, see the LT1351 through LT1365
data sheets.
U
APPLICATIO S
■
Wideband Amplifiers
■
Buffers
Active Filters
■
■
Video and RF Amplification
, LTC and LT are registered trademarks of Linear Technology Corporation.
■
Cable Drivers
■
Data Acquisition Systems
U
TYPICAL APPLICATIO
Filter Frequency Response
10
0
4MHz, 4th Order Butterworth Filter
–10
–20
232Ω
274Ω
–30
–40
47pF
232Ω
665Ω
–
V
IN
–50
–60
22pF
274Ω
562Ω
–
+
LT1812
220pF
+
LT1812
V
–70
–80
–90
470pF
OUT
V
V
= ±5V
S
= 600mV
P-P
IN
PEAKING < 0.12dB
1812 TA01
0.1
1
10
100
FREQUENCY (MHz)
1812 TA02
1
LT1812
W W U W
U W
U
ABSOLUTE AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
(Note 1)
Total Supply Voltage (V+ to V–)............................. 12.6V
Differential Input Voltage (Transient Only, Note 2) ... ±3V
Input Voltage ........................................................... ±VS
Output Short-Circuit Duration (Note 3)............ Indefinite
Operating Temperature Range (Note 8) ... –40°C to 85°C
Specified Temperature Range
(Note 8) .............................................. –40°C to 85°C
Maximum Junction Temperature ......................... 150°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................... 300°C
ORDER PART
TOP VIEW
NUMBER
NC
–IN
+IN
1
2
3
4
8
7
6
5
SHDN
LT1812CS8
LT1812IS8
+
V
V
OUT
–
V
NC
S8 PART MARKING
S8 PACKAGE
8-LEAD PLASTIC SO
1812
1812I
TJMAX = 150°C, θJA = 80°C/ W (NOTE 9)
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
TA = 25°C, VS = ±5V, VCM = 0V unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
0.4
30
MAX
1.5
UNITS
mV
V
Input Offset Voltage
Input Offset Current
Input Bias Current
(Note 4)
OS
I
I
400
±4
nA
OS
–0.9
8
µA
B
e
Input Noise Voltage Density
Input Noise Current Density
Input Resistance
f = 10kHz
f = 10kHz
nV/√Hz
pA/√Hz
n
i
1
n
R
V
CM
= ±3.5V
3
10
1.5
MΩ
MΩ
IN
Differential
C
V
Input Capacitance
2
pF
IN
Input Voltage Range (Positive)
Input Voltage Range (Negative)
3.5
75
4.2
–4.2
V
V
CM
–3.5
CMRR
Common Mode Rejection Ratio
Minimum Supply Voltage
V
= ±3.5V
85
±1.25
97
dB
V
CM
±2
PSRR
Power Supply Rejection Ratio
Large-Signal Voltage Gain
V = ±2V to ±5.5V
S
78
dB
A
V
V
OUT
V
OUT
= ±3V, R = 500Ω
= ±3V, R = 100Ω
1.5
1.0
3.0
2.5
V/mV
V/mV
VOL
OUT
L
L
Maximum Output Swing
R = 500Ω, 30mV Overdrive
R = 100Ω, 30mV Overdrive
±3.80
±3.35
±4.0
±3.5
V
V
L
L
I
I
Maximum Output Current
Output Short-Circuit Current
Slew Rate
V
V
= ±3V, 30mV Overdrive
±40
±75
500
±60
±110
750
40
mA
mA
V/µs
MHz
MHz
ns
OUT
SC
OUT
OUT
= 0V, 1V Overdrive (Note 3)
SR
A = –1 (Note 5)
V
FPBW
GBW
Full Power Bandwidth
Gain Bandwidth Product
Rise Time, Fall Time
Overshoot
3V Peak (Note 6)
f = 200kHz
75
100
2
t , t
A = 1, 10% to 90%, 0.1V, R = 100Ω
V L
r
f
OS
A = 1, 0.1V, R = 100Ω
V
25
%
L
t
t
Propagation Delay
Settling Time
A = 1, 50% V to 50% V , 0.1V, R = 100Ω
2.8
ns
PD
s
V
IN
OUT
L
5V Step, 0.1%, A = –1
30
ns
V
THD
Total Harmonic Distortion
Differential Gain
f = 1MHz, V
= 2V , A = 2, R = 500Ω
–76
0.12
0.07
0.4
dB
OUT
P-P
V
L
V
OUT
V
OUT
= 2V , A = 2, R = 150Ω
%
P-P
V
L
Differential Phase
Output Resistance
= 2V , A = 2, R = 150Ω
DEG
Ω
P-P
V
L
R
A = 1, f = 1MHz
V
OUT
2
LT1812
ELECTRICAL CHARACTERISTICS
TA = 25°C, VS = ±5V, VCM = 0V unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
–
I
SHDN Pin Current
SHDN > V + 2.0V (On)
SHDN < V + 0.4V (Off)
0
±1
µA
µA
SHDN
–
–100
–50
–
–
I
Supply Current
SHDN > V + 2.0V (On)
3
50
3.6
100
mA
µA
S
SHDN < V + 0.4V (Off)
TA = 25°C, VS = 5V, VCM = 2.5V, RL to 2.5V unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
0.5
30
MAX
2.0
UNITS
mV
V
OS
Input Offset Voltage
Input Offset Current
Input Bias Current
(Note 4)
I
I
400
±4
nA
OS
–1.0
8
µA
B
e
Input Noise Voltage Density
Input Noise Current Density
Input Resistance
f = 10kHz
f = 10kHz
nV/√Hz
pA/√Hz
n
i
1
n
R
IN
V
= 1.5V to 3.5V
3
10
1.5
MΩ
MΩ
CM
Differential
C
V
Input Capacitance
2
pF
IN
Input Voltage Range (Positive)
Input Voltage Range (Negative)
3.5
73
4
1
V
V
CM
1.5
CMRR
Common Mode Rejection Ratio
Large-Signal Voltage Gain
V
= 1.5V to 3.5V
82
dB
CM
A
VOL
V
OUT
V
OUT
= 1.5V to 3.5V, R = 500Ω
= 1.5V to 3.5V, R = 100Ω
1.0
0.7
2.0
1.5
V/mV
V/mV
L
L
V
OUT
Maximum Output Swing (Positive)
Maximum Output Swing (Negative)
R = 500Ω, 30mV Overdrive
L
3.9
3.7
4.1
3.9
V
V
L
R = 100Ω, 30mV Overdrive
R = 500Ω, 30mV Overdrive
0.9
1.1
1.1
1.3
V
V
L
R = 100Ω, 30mV Overdrive
L
I
I
Maximum Output Current
Output Short-Circuit Current
Slew Rate
V
V
= 3.5V or 1.5V, 30mV Overdrive
= 2.5V, 1V Overdrive (Note 3)
±25
±55
200
±40
±80
350
55
mA
mA
V/µs
MHz
MHz
ns
OUT
SC
OUT
OUT
SR
A = –1 (Note 5)
V
FPBW
GBW
Full Power Bandwidth
Gain Bandwidth Product
Rise Time, Fall Time
Overshoot
1V Peak (Note 6)
f = 200kHz
65
94
t , t
A = 1, 10% to 90%, 0.1V, R = 100Ω
V
2.1
25
r
f
L
OS
A = 1, 0.1V, R = 100Ω
V
%
L
t
t
Propagation Delay
Settling Time
A = 1, 50% V to 50% V , 0.1V, R = 100Ω
3
ns
PD
s
V
IN
OUT
L
2V Step, 0.1%, A = –1
30
ns
V
THD
Total Harmonic Distortion
Differential Gain
f = 1MHz, V
= 2V , A = 2, R = 500Ω
–75
0.22
0.21
0.45
dB
OUT
P-P
V
L
V
OUT
V
OUT
= 2V , A = 2, R = 150Ω
%
P-P
V
L
Differential Phase
Output Resistance
SHDN Pin Current
= 2V , A = 2, R = 150Ω
DEG
Ω
P-P
V
L
R
OUT
A = 1, f = 1MHz
V
–
–
I
SHDN > V + 2.0V (On)
SHDN < V + 0.4V (Off)
0
–20
±1
µA
µA
SHDN
–50
–
–
I
Supply Current
SHDN > V + 2.0V (On)
SHDN < V + 0.4V (Off)
2.7
20
3.6
50
mA
µA
S
0°C ≤ TA ≤ 70°C, VS = ±5V, VCM = 0V unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
(Note 4)
MIN
TYP
MAX
2
UNITS
mV
V
Input Offset Voltage
Input Offset Voltage Drift
Input Offset Current
Input Bias Current
OS
∆V /∆T
(Note 7)
10
15
µV/°C
nA
OS
I
I
500
±5
OS
B
µA
3
LT1812
ELECTRICAL CHARACTERISTICS
0°C ≤ TA ≤ 70°C. VS = ±5V, VCM = 0V unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
Input Voltage Range (Positive)
Input Voltage Range (Negative)
3.5
V
V
CM
–3.5
CMRR
Common Mode Rejection Ratio
Minimum Supply Voltage
V
CM
= ±3.5V
73
dB
V
±2
PSRR
Power Supply Rejection Ratio
Large-Signal Voltage Gain
V = ±2V to ±5.5V
76
dB
S
A
V
V
OUT
V
OUT
= ±3V, R = 500Ω
1.0
0.7
V/mV
V/mV
VOL
OUT
L
= ±3V, R = 100Ω
L
Maximum Output Swing
R = 500Ω, 30mV Overdrive
±3.70
±3.25
V
V
L
R = 100Ω, 30mV Overdrive
L
I
I
Maximum Output Current
Output Short-Circuit Current
Slew Rate
V
V
= ±3V, 30mV Overdrive
±35
±60
400
65
mA
mA
OUT
SC
OUT
OUT
= 0V, 1V Overdrive (Note 3)
SR
A = –1 (Note 5)
V
V/µs
MHz
GBW
Gain Bandwidth Product
SHDN Pin Current
f = 200kHz
–
–
I
SHDN > V + 2.0V (On)
SHDN < V + 0.4V (Off)
±1.5
µA
µA
SHDN
–150
–
–
I
Supply Current
SHDN > V + 2.0V (On)
SHDN < V + 0.4V (Off)
4.6
150
mA
µA
S
0°C ≤ TA ≤ 70°C, VS = 5V, VCM = 2.5V, RL to 2.5V unless otherwise noted.
V
Input Offset Voltage
Input Offset Voltage Drift
Input Offset Current
Input Bias Current
(Note 4)
2.5
15
mV
µV/°C
nA
OS
∆V /∆T
(Note 7)
10
OS
I
I
500
±5
OS
B
µA
V
Input Voltage Range (Positive)
Input Voltage Range (Negative)
3.5
71
V
V
CM
1.5
CMRR
Common Mode Rejection Ratio
Large-Signal Voltage Gain
V
= 1.5V to 3.5V
dB
CM
A
V
OUT
V
OUT
= 1.5V to 3.5V, R = 500Ω
= 1.5V to 3.5V, R = 100Ω
0.7
0.5
V/mV
V/mV
VOL
L
L
V
Maximum Output Swing (Positive)
Maximum Output Swing (Negative)
R = 500Ω, 30mV Overdrive
L
3.8
3.6
V
V
OUT
L
R = 100Ω, 30mV Overdrive
R = 500Ω, 30mV Overdrive
1.2
1.4
V
V
L
R = 100Ω, 30mV Overdrive
L
I
I
Maximum Output Current
Output Short-Circuit Current
Slew Rate
V
V
= 3.5V or 1.5V, 30mV Overdrive
= 2.5V, 1V Overdrive (Note 3)
±20
±45
150
55
mA
mA
OUT
SC
OUT
OUT
SR
A = –1 (Note 5)
V
V/µs
MHz
GBW
Gain Bandwidth Product
SHDN Pin Current
f = 200kHz
–
–
I
SHDN > V + 2.0V (On)
SHDN < V + 0.4V (Off)
±1.5
µA
µA
SHDN
–75
–
–
I
Supply Current
SHDN > V + 2.0V (On)
SHDN < V + 0.4V (Off)
4.5
75
mA
µA
S
–40°C ≤ TA ≤ 85°C. VS = ±5V, VCM = 0V unless otherwise noted (Note 8).
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
3
UNITS
mV
V
Input Offset Voltage
Input Offset Voltage Drift
Input Offset Current
Input Bias Current
(Note 4)
OS
∆V /∆T
OS
(Note 7)
10
30
µV/°C
nA
I
I
600
±6
OS
B
µA
V
Input Voltage Range (Positive)
Input Voltage Range (Negative)
3.5
72
V
V
CM
–3.5
CMRR
Common Mode Rejection Ratio
V
CM
= ±3.5V
dB
4
LT1812
ELECTRICAL CHARACTERISTICS
–40°C ≤ TA ≤ 85°C. VS = ±5V, VCM = 0V unless otherwise noted (Note 8).
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
Minimum Supply Voltage
Power Supply Rejection Ratio
Large-Signal Voltage Gain
±2
PSRR
V = ±2V to ±5.5V
75
dB
S
A
V
OUT
V
OUT
= ±3V, R = 500Ω
= ±3V, R = 100Ω
0.8
0.6
V/mV
V/mV
VOL
L
L
V
Maximum Output Swing
R = 500Ω, 30mV Overdrive
L
±3.60
±3.15
V
V
OUT
L
R = 100Ω, 30mV Overdrive
I
I
Maximum Output Current
Output Short-Circuit Current
Slew Rate
V
V
= ±3V, 30mV Overdrive
±30
±55
350
60
mA
mA
OUT
SC
OUT
OUT
= 0V, 1V Overdrive (Note 3)
SR
A = –1 (Note 5)
V
V/µs
MHz
GBW
Gain Bandwidth Product
SHDN Pin Current
f = 200kHz
–
–
I
SHDN > V + 2.0V (On)
SHDN < V + 0.4V (Off)
±2
µA
µA
SHDN
–200
–
–
I
Supply Current
SHDN > V + 2.0V (On)
SHDN < V + 0.4V (Off)
5
200
mA
µA
S
–40°C ≤ TA ≤ 85°C, VS = 5V, VCM = 2.5V, RL to 2.5V unless otherwise noted (Note 8).
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
3.5
30
UNITS
mV
V
Input Offset Voltage
Input Offset Voltage Drift
Input Offset Current
Input Bias Current
(Note 4)
OS
∆V /∆T
OS
(Note 7)
10
µV/°C
nA
I
I
600
±6
OS
B
µA
V
Input Voltage Range (Positive)
Input Voltage Range (Negative)
3.5
70
V
V
CM
1.5
CMRR
Common Mode Rejection Ratio
Large-Signal Voltage Gain
V
= 1.5V to 3.5V
dB
CM
A
V
OUT
V
OUT
= 1.5V to 3.5V, R = 500Ω
= 2.0V to 3.0V, R = 100Ω
0.6
0.4
V/mV
V/mV
VOL
L
L
V
Maximum Output Swing (Positive)
Maximum Output Swing (Negative)
R = 500Ω, 30mV Overdrive
L
3.7
3.5
V
V
OUT
L
R = 100Ω, 30mV Overdrive
R = 500Ω, 30mV Overdrive
1.3
1.5
V
V
L
R = 100Ω, 30mV Overdrive
L
I
I
Maximum Output Current
Output Short-Circuit Current
Slew Rate
V
V
= 3.5V or 1.5V, 30mV Overdrive
= 2.5V, 1V Overdrive (Note 3)
±17
±40
125
50
mA
mA
OUT
SC
OUT
OUT
SR
A = –1 (Note 5)
V
V/µs
MHz
GBW
Gain Bandwidth Product
SHDN Pin Current
f = 200kHz
–
–
I
SHDN > V + 2.0V (On)
SHDN < V + 0.4V (Off)
±2
µA
µA
SHDN
–100
–
–
I
Supply Current
SHDN > V + 2.0V (On)
SHDN < V + 0.4V (Off)
5
100
mA
µA
S
Note 1: Absolute Maximum Ratings are those values beyond which the life of
the device may be impaired.
Note 6: Full power bandwidth is calculated from the slew rate:
FPBW = SR/2πV .
P
Note 2: Differential inputs of ±3V are appropriate for transient operation only,
such as during slewing. Large sustained differential inputs can cause
excessive power dissipation and may damage the part.
Note 7: This parameter is not 100% tested.
Note 8: The LT1812C is guaranteed to meet specified performance from
0°C to 70°C. The LT1812C is designed, characterized and expected to meet
specified performance from –40°C to 85°C but is not tested or QA sampled
Note 3: A heat sink may be required to keep the junction temperature below
absolute maximum when the output is shorted indefinitely.
Note 4: Input offset voltage is pulse tested and is exclusive of warm-up drift.
Note 5: Slew rate is measured between ±2V on the output with ±3V input for
at these temperatures. The LT1812I is guaranteed to meet specified
performance from –40°C to 85°C.
2
Note 9: θ is specified for a 2500mm board covered with 2 oz copper on
JA
both sides. Thermal resistance varies, depending upon the amount of PC
board metal attached to the device. For this package in particular, power is
dissipated primarily through Pin 4, which should therefore, have a good
thermal connection to a copper plane.
±5V supplies and 2V on the output with a 3V input for single 5V
supplies.
P-P
P-P
5
LT1812
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Input Common Mode Range
Input Bias Current vs
Supply Current vs Temperature
vs Supply Voltage
Common Mode Voltage
+
5
4
3
2
1
0
V
0
–0.5
–1.0
–1.5
–2.0
T
= 25°C
= ±5V
A
S
–0.5
–1.0
–1.5
–2.0
V
V
= ±5V
S
T
= 25°C
OS
A
V
S
= ±2.5V
∆V < 1mV
2.0
1.5
1.0
0.5
–
V
0
2.5
–5.0
5.0
50
75 100 125
0
2
3
4
5
6
7
–2.5
–50 –25
0
25
TEMPERATURE (°C)
1
SUPPLY VOLTAGE (± V)
INPUT COMMON MODE VOLTAGE (V)
1812 G03
1812 G01
1812 G02
Input Bias Current
vs Temperature
Open-Loop Gain
vs Resistive Load
Input Noise Spectral Density
100
10
1
10
75.0
72.5
70.0
67.5
65.0
62.5
60
0
T
= 25°C
T
A
= 25°C
= ±5V
= 101
= 10k
A
V
A
S
V
–0.2
R
S
–0.4
–0.6
–0.8
–1.0
–1.2
V
V
= ±5V
S
S
i
n
1
e
n
= ±2.5V
V
S
= ±5V
V
S
= ±2.5V
0.1
100k
–1.4
100
1k
LOAD RESISTANCE (Ω)
50
100 125
10
100
1k
FREQUENCY (Hz)
10k
10k
–50 –25
0
25
75
TEMPERATURE (°C)
1812 G06
1812 G05
1812 G04
Output Voltage Swing
vs Load Current
Output Voltage Swing
vs Supply Voltage
Open-Loop Gain vs Temperature
+
+
V
75.0
72.5
70.0
67.5
V
V
V
= ±5V
= 30mV
85°C
T
= 25°C
IN
V
S
V
O
= ±5V
= ±3V
S
IN
A
–0.5
–1.0
–1.5
–2.0
–0.5
–1.0
–1.5
–2.0
V
= 30mV
R
= 500Ω
= 100Ω
L
25°C
– 40°C
R
R
= 500Ω
= 100Ω
R
L
L
L
2.0
1.5
1.0
0.5
2.0
1.5
1.0
0.5
65.0
62.5
60.0
R
= 100Ω
L
R
L
= 500Ω
–
–
V
V
50
100 125
0
2
3
4
5
7
–40
0
–50 –25
0
25
75
6
–60
–20
20
40
60
1
SUPPLY VOLTAGE (± V)
TEMPERATURE (°C)
OUTPUT CURRENT (mA)
1812 G07
1812 G08
1812 G09
6
LT1812
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Output Short-Circuit Current
vs Temperature
Settling Time vs Output Step
Output Impedance vs Frequency
5
4
100
10
120
115
110
105
V
S
= ± 5V
SOURCE
A
V
= 100
3
A
V
= 10
A
2
= 1
1
1
V
SINK
0
0.1
–1
–2
–3
–4
–5
T
V
A
= 25°C
= ±5V
= –1
A
S
V
100
95
0.01
0.001
R = 500Ω
F
T
= 25°C
= ± 5V
S
C = 3pF
F
A
V
0.1% SETTLING
90
50
TEMPERATURE (°C)
100 125
0
10
5
15
20
25
35
10k
100k
1M
FREQUENCY (Hz)
10M
100M
–50 –25
0
25
75
30
SETTLING TIME (ns)
1812 G12
1812 G10
1812 G11
Shutdown Supply Current
vs Temperature
Gain Bandwidth and Phase
Margin vs Temperature
Gain and Phase vs Frequency
70
60
50
40
30
20
10
0
120
100
80
115
105
95
70
60
–
T
= 25°C
V
SHDN
= V + 0.4V
R = 500Ω
L
A
V
F
A
= –1
R
= R = 500Ω
G
GBW
= ±5V
V
S
= ±5V
V
S
50
40
30
20
10
PHASE
GAIN
GBW
= ±2.5V
60
V
S
±2.5V ±5V
±5V
40
±2.5V
85
40
38
36
20
V
S
= ±2.5V
PHASE MARGIN
V
= ±5V
S
0
PHASE MARGIN
–20
–40
V
= ±2.5V
S
–10
0
10k
100k
1M
10M
100M 1000M
50
100 125
50
125
–50 –25
0
25
75
–50 –25
0
25
75
100
FREQUENCY (Hz)
TEMPERATURE (°C)
TEMPERATURE (°C)
1812 G13
1812 G14
1812 G15
Gain vs Frequency
Gain vs Frequency
Gain vs Frequency
6
4
2
0
12
8
8
6
C = 1000pF
L
T
A
V
= 25°C
= –1
T
= 25°C
A
V
S
T
= 25°C
= 2
A
V
A
V
L
A
= 1
A
C = 500pF
L
V
S
= ±2.5V
= ±5V
NO R
R
= 100Ω
L
R = R = 500Ω
NO R
F
G
C = 200pF
L
4
L
V
= ±5V
C = 100pF
L
S
–2
–4
4
2
C = 50pF
L
V
= ±2.5V
V = ±5V
S
S
0
C = 0
L
–6
–8
0
–2
–4
–6
–10
–12
–14
–4
–8
1M
10M
100M
500M
1
10M
FREQUENCY (Hz)
100M 200M
1M
10M
100M
500M
FREQUENCY (Hz)
FREQUENCY (Hz)
1812 G16
1812 G18
1812 G17
7
LT1812
TYPICAL PERFOR A CE CHARACTERISTICS
U W
Power Supply Rejection Ratio
vs Frequency
Common Mode Rejection Ratio
vs Frequency
Gain Bandwidth and Phase
Margin vs Supply Voltage
100
80
60
40
20
0
100
80
60
40
20
0
110
90
T
A
V
= 25°C
T = 25°C
A
V = ±5V
S
T
= 25°C
A
V
S
A
GBW
= 1
R
R
= 500Ω
L
L
= ±5V
GBW
= 100Ω
–PSRR
+PSRR
70
45
40
35
PHASE MARGIN
R
= 100Ω
L
PHASE MARGIN
= 500Ω
R
L
1k
10k
100k
1M
10M
100M
1k
10k
100k
1M
10M
100M
1
2
4
5
6
7
0
3
FREQUENCY (Hz)
FREQUENCY (Hz)
SUPPLY VOLTAGE (±V)
1812 G20
1812 G21
1812 G19
Slew Rate vs Supply Voltage
Slew Rate vs Supply Voltage
Slew Rate vs Input Level
600
500
400
300
200
1200
1100
1000
900
800
700
600
500
400
300
200
1200
1000
800
T
A
V
=25°C
T
A
V
=25°C
T
A
V
=25°C
= –1
= ±5V
A
V
A
V
A
V
S
= –1
= –1
= V
S(TOTAL)
/2
= ±1V
IN
IN
R = R = R = 500Ω
R = R = R = 500Ω
R = R = R = 500Ω
F
G
L
F
G
L
F
G
L
–
SR
–
+
SR
SR
+
–
SR
SR
+
SR
600
400
200
0
2
3
4
5
6
7
0
2
3
4
5
6
7
0
2
3
4
5
6
7
8
1
1
1
SUPPLY VOLTAGE (±V)
SUPPLY VOLTAGE (±V)
INPUT LEVEL (V
)
P-P
1812 G22
1812 G23
1812 G24
Total Harmonic Distortion + Noise
vs Frequency
Undistorted Output Swing
vs Frequency
Slew Rate vs Temperature
9
8
7
6
5
4
3
2
1
0
0.01
1200
1000
800
A
V
= –1
–
SR
+
A
V
= 1
V
S
= ±5V
SR
= ±5V
A = –1
V
V
S
0.005
A
V
= 1
600
–
SR
V
V
= ±2.5V
S
400
200
0
0.002
0.001
+
SR
T
= 25°C
= ±5V
= 2V
T
= 25°C
= ±5V
= 100Ω
A
S
O
A
S
L
= ±2.5V
S
V
V
V
R
P-P
R
= 500Ω
2% MAX DISTORTION
1M
FREQUENCY (Hz)
L
100k
10M
100M
50
TEMPERATURE (°C)
100 125
–50 –25
0
25
75
10
100
1k
FREQUENCY (Hz)
10k
100k
1812 G27
1812 G26
1812 G25
8
LT1812
U W
TYPICAL PERFOR A CE CHARACTERISTICS
2nd and 3rd Harmonic Distortion
vs Frequency
Differential Gain and Phase
vs Supply Voltage
Capacitive Load Handling
100
90
0.25
0.20
0.15
0.10
0.05
0
–30
–40
–50
–60
–70
–80
–90
–100
T
= 25°C
= ±5V
T
= 25°C
= 2
A
S
A
DIFFERENTIAL GAIN
V
A
V
V
V
S
O
R
= 150Ω
L
= ±5V
80
= 2V
P-P
A = 1
V
70
2ND HARMONIC
3RD HARMONIC
DIFFERENTIAL GAIN
= 1k
R
60
50
L
R
L
= 100Ω
0.25
0.20
0.15
0.10
0.05
0
A
= –1
V
DIFFERENTIAL PHASE
= 150Ω
40
30
20
10
0
R
L
DIFFERENTIAL PHASE
= 1k
3RD HARMONIC
2ND HARMONIC
R
L
R
= 500Ω
L
T
= 25°C
A
10
100
1000
10000
100k
10M
1M
4
8
10
12
6
FREQUENCY (Hz)
CAPACITIVE LOAD (pF)
TOTAL SUPPLY VOLTAGE (V)
1812 G30
1812 G28
1812 G29
Small-Signal Transient,
AV = –1
Small-Signal Transient,
AV = 1
Small-Signal Transient,
AV = 1, CL = 1000pF
1812 G31
1812 G32
1812 G33
Large-Signal Transient,
AV = –1
Large-Signal Transient,
AV = 1
Large-Signal Transient,
AV = 1, CL = 1000pF
1812 G36
1812 G34
1812 G35
9
LT1812
W U U
U
APPLICATIO S I FOR ATIO
Layout and Passive Components
capacitive load increases, both the bandwidth and phase
margin decrease so there will be peaking in the frequency
domainandinthetransientresponse. Coaxialcablecanbe
driven directly, but for best pulse fidelity, a resistor of
value equal to the characteristic impedance of the cable
(i.e., 75Ω) should be placed in series with the output. The
other end of the cable should be terminated with the same
value resistor to ground.
The LT1812 amplifier is more tolerant of less than ideal
layouts than other high speed amplifiers. For maximum
performance (for example, fast settling) use a ground
plane,shortleadlengthsandRF-qualitybypasscapacitors
(0.01µF to 0.1µF). For high drive current applications, use
low ESR bypass capacitors (1µF to 10µF tantalum).
The parallel combination of the feedback resistor and gain
setting resistor on the inverting input combine with the
input capacitance to form a pole that can cause peaking or
even oscillations. If feedback resistors greater than 2k are
used, a parallel capacitor of value
Slew Rate
The slew rate is proportional to the differential input
voltage. Highest slew rates are therefore seen in the
lowest gain configurations. For example, a 5V output step
in a gain of 10 has a 0.5V input step, whereas in unity gain
there is a 5V input step. The LT1812 is tested for slew rate
in a gain of –1. Lower slew rates occur in higher gain
configurations.
CF > RG • CIN/RF
should be used to cancel the input pole and optimize
dynamic performance. For applications where the DC
noise gain is 1 and a large feedback resistor is used, CF
should be greater than or equal to CIN. An example would
be an I-to-V converter.
Shutdown
The LT1812 has a shutdown pin (SHDN, Pin 8) for
conserving power. When this pin is open or biased at
least 2V above the negative supply, the part operates
normally. When pulled down to V–, the supply current
drops to about 50µA. Typically, the turn-off delay is 1µs
and the turn-on delay 0.5µs. The current out of the SHDN
pin is also typically 50µA. In shutdown mode, the ampli-
fier output is not isolated from the inputs, so the LT1812
shutdown feature cannot be used for multiplexing appli-
cations. The 50µA typical shutdown current is exclusive
of any output (load) current. In order to prevent load
current (and maximize the power savings), either the
load needs to be disconnected, or the input signal needs
to be 0V. Even in shutdown mode, the LT1812 can still
drive significant current into a load. For example, in an
AV = 1 configuration, when driven with a 1V DC input, the
LT1812 drives 2mA into a 100Ω load. It takes about
500µs for the load current to reach this value.
Input Considerations
Each of the LT1812 amplifier inputs is the base of an NPN
and PNP transistor whose base currents are of opposite
polarity and provide first-order bias current cancellation.
BecauseofvariationinthematchingofNPNandPNPbeta,
the polarity of the input bias current can be positive or
negative. The offset current does not depend on beta
matching and is well controlled. The use of balanced
source resistance at each input is recommended for
applications where DC accuracy must be maximized. The
inputs can withstand differential input voltages of up to 3V
without damage and need no clamping or source resis-
tance for protection.
The device should not be used as a comparator because
with sustained differential inputs, excessive power dissi-
pation may result.
Capacitive Loading
Power Dissipation
The LT1812 is stable with a 1000pF capacitive load, which
is outstanding for a 100MHz amplifier. This is accom-
plished by sensing the load induced output pole and
adding compensation at the amplifier gain node. As the
The LT1812 combines high speed and large output drive
in a small package. It is possible to exceed the maximum
junction temperature under certain conditions. Maximum
10
LT1812
W U U
APPLICATIO S I FOR ATIO
U
junction temperature (TJ) is calculated from the ambient
appears across the resistor generating currents that are
mirrored into the high impedance node. Complementary
followers form an output stage that buffers the gain node
from the load. The bandwidth is set by the input resistor
andthecapacitanceonthehighimpedancenode.Theslew
rate is determined by the current available to charge the
gainnodecapacitance.Thiscurrentisthedifferentialinput
voltage divided by R1, so the slew rate is proportional to
the input. Highest slew rates are therefore seen in the
lowest gain configurations. The RC network across the
output stage is bootstrapped when the amplifier is driving
a light or moderate load and has no effect under normal
operation. When driving capacitive loads (or a low value
resistive load) the network is incompletely bootstrapped
and adds to the compensation at the high impedance
node. The added capacitance slows down the amplifier
which improves the phase margin by moving the unity-
gain cross away from the pole formed by the output
impedanceandthecapacitiveload.Thezerocreatedbythe
RC combination adds phase to ensure that the total phase
lag does not exceed 180 degrees (zero phase margin) and
the amplifier remains stable. In this way, the LT1812 is
stablewithupto1000pFcapacitiveloadsinunitygain,and
even higher capacitive loads in higher closed-loop gain
configurations.
temperature (TA) and power dissipation (PD) as follows:
LT1812CS8: TJ = TA + (PD • 80°C/W) (Note 9)
Power dissipation is composed of two parts. The first is
due to the quiescent supply current and the second is due
to on-chip dissipation caused by the load current. The
worst-case load induced power occurs when the output
voltage is at 1/2 of either supply voltage (or the maximum
swing if less than 1/2 supply voltage). Therefore PDMAX is:
PDMAX = (V+ – V–)(ISMAX) + (V+/2)2/RL or
PDMAX = (V+ – V–)(ISMAX) + (V+ – VOMAX)(VOMAX/RL)
Example: LT1812CS8 at 70°C, VS = ±5V, RL = 100Ω
PDMAX = (10V)(4.5mA) + (2.5V)2/100Ω = 108mW
TJMAX = 70°C + (108mW)(80°C/W) = 79°C
Circuit Operation
The LT1812 circuit topology is a true voltage feedback
amplifier that has the slewing behavior of a current feed-
back amplifier. The operation of the circuit can be under-
stood by referring to the Simplified Schematic. The inputs
are buffered by complementary NPN and PNP emitter
followers that drive a 300Ω resistor. The input voltage
W
W
SI PLIFIED SCHEMATIC
+
V
R
B
R1
300Ω
C
C
+IN
R
C
OUT
–IN
C
BIAS
CONTROL
SHDN
–
V
1812 SS
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.
11
LT1812
U
TYPICAL APPLICATIO
Single 5V Supply 10MS/s 12-Bit ADC Buffer
V
P-P
IN
2V
+
12 BITS
10MS/s
68Ω
2.5V
DC
LT1812
LTC1420
470pF
–
1812 TA03
U
PACKAGE DESCRIPTION
S8 Package
8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.189 – 0.197*
(4.801 – 5.004)
0.010 – 0.020
(0.254 – 0.508)
7
5
8
6
× 45°
0.053 – 0.069
(1.346 – 1.752)
0.004 – 0.010
(0.101 – 0.254)
0.008 – 0.010
(0.203 – 0.254)
0°– 8° TYP
0.150 – 0.157**
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
0.016 – 0.050
(0.406 – 1.270)
0.050
(1.270)
BSC
0.014 – 0.019
(0.355 – 0.483)
TYP
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
SO8 1298
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
1
3
4
2
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
4mA Supply Current, 1mV Max V , 1µA Max I
LT1360/LT1361/LT1362
LT1363/LT1364/LT1365
LT1395/LT1396/LT1397
LT1398/LT1399
Single/Dual/Quad 50MHz, 800V/µs, C-LoadTM Amplifiers
Single/Dual/Quad 70MHz, 1000V/µs C-Load Amplifiers
Single/Dual/Quad 400MHz Current Feedback Amplifiers
Dual/Triple 300MHz Current Feedback Amplifiers
Dual 3mA, 100MHz, 750V/µs Operational Amplifier
OS
B
50mA Output Current, 1.5mV Max V , 2µA Max I
OS
B
4.6mA Supply Current, 800V/µs, 80mA Output Current
4.5mA Supply Current, 80mA Output Current, Shutdown
Dual Version of the LT1812
LT1813
C-Load is a trademark of Linear Technology Corporation.
1812f LT/TP 0200 4K • PRINTED IN USA
LINEAR TECHNOLOGY CORPORATION 1999
12 LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
●
●
(408)432-1900 FAX:(408)434-0507 www.linear-tech.com
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