LT1990-10
±250V Input Range,
100kHz, G =10, Micropower,
Difference Amplifier
DESCRIPTION
FEATURES
Gain = 10
n –3dB Bandwidth = 100kHz
n High Common Mode Voltage Range:
nn ±250V (V = ±15V)
S
nn 85V Window (V = 5V, 0V)
S
n Common Mode Rejection Ratio: 60dB Min
n Input Protection to ±350V
n Gain Error: 0.8% Max
n PSRR: 82dB Min
n High Input Impedance: 2MΩ Differential,
500kΩ Common Mode
n Micropower: 180µA Max Supply Current
n Wide Supply Range: 2.7V to 36V
n Rail-to-Rail Output
n 8-pin SO and pin FMEA Compatible MSOP Packages
The LT®1990-10 is a micropower precision difference amplifier with a very high common mode input voltage range,
a fixed gain of 10 and 100kHz bandwidth. The LT1990-10
operates over a ±250V common mode voltage range on a
±15V supply. The inputs are fault protected from common
mode voltage transients up to ±350V and differential
voltages up to ±500V. The LT1990-10 is ideally suited for
both high side and low side current or voltage monitoring.
n
On a single 5V supply, the LT1990-10 has an adjustable
85V input range, 60dB min CMRR and draws less than
180µA supply current. The rail-to-rail output maximizes
the dynamic range, especially important for single supplies as low as 2.7V.
The LT1990-10 is specified for single 3V, 5V and ±15V
supplies over the industrial temperature range.
APPLICATIONS
The LT1990-10 is available in the 8-pin SO and pin FMEA
compatible MSOP packages.
Battery Cell Voltage Monitoring
High Voltage Current Sensing
n Signal Acquisition in Noisy Environments
n Input Protection
n Fault Protected Front Ends
n Level Sensing
n Isolation
n
n
All registered trademarks and trademarks are the property of their respective owners.
TYPICAL APPLICATION
Full-Bridge Load Current Monitor
+VSOURCE
5V
LT1990-10
1M
– +
RS
–12V ≤ VCM ≤ 73V
VOUT = VREF ± (10 • IL • RS)
OUT
LT6650
GND FB
1nF
54.9k
VOUT
+
VREF = 1.5V
IN
10k
100k
–
1M
IL
900k
10k
40k
40k
900k
100k
20k
199010 TA01
1µF
Rev 0
For more information www.analog.com
1
LT1990-10
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
Total Supply Voltage (V + to V–).................................36V
Input Voltage Range
Each Input Continuous.......................................±250V
Each Input Transient (0.1s).................................±350V
Differential.........................................................±500V
Output Short-Circuit Duration (Note 3)............. Indefinite
Operating Temperature Range (Note 4)
LT1990I-10.......................................... –55°C to 125°C
Specified Temperature Range (Note 5)
LT1990I-10............................................–40°C to 85°C
Junction Temperature............................................ 150°C
Storage Temperature Range................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec.)................... 300°C
PIN CONFIGURATION
TOP VIEW
TOP VIEW
–IN
NC
NC
+IN
1
2
3
4
8
7
6
5
REF
V+
OUT
V–
REF 1
8
NC
–IN 2
7
V+
+IN 3
6
OUT
5
NC
V–
MS8 PACKAGE
8-LEAD PLASTIC MSOP
4
S8 PACKAGE
8-LEAD PLASTIC SO
TJMAX = 150°C, θJA = 250°C/W
TJMAX = 150°C, θJA = 190°C/W
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
SPECIFIED TEMPERATURE RANGE
LT1990IS8-10#PBF
LT1990IS8-10#TRPBF
199010
8-Lead Plastic SO
–40°C to 85°C
LT1990IMS8-10#PBF
LT1990IMS8-10#TRPBF
LTHBQ
8-Lead Plastic MSOP
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
For more information on tape and reel specifications, go to: Tape and reel specifications. Some packages are available in 500 unit reels through designated
sales channels with #TRMPBF suffix.
Rev 0
2
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LT1990-10
3V/5V ELECTRICAL CHARACTERISTICS
VS = V+, V–; VS = 3V, 0V; VS = 5V, 0V; RL = 10kΩ, VCM = VREF =
half supply, TA = 25°C, unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
G
Gain
∆G
Gain Error
VOUT = 0.5V to (+VS) –0.75V
0.2
0.01
MAX
UNITS
10
0.8
%
GNL
Gain Nonlinearity
VS = 5V, 0V; VOUT = 0.5V to 4.25V
VCM
Input Voltage Range
Guaranteed by CMRR
VS = 3V, 0V; VREF = 1.25V
VS = 5V, 0V; VREF = 1.25V
VS = 5V, 0V; VREF = 2.5V
-5
-5
-38
CMRR
Common Mode Rejection Ratio
RTI (Referred to Input)
VS = 3V, 0V (Note 6)
VCM = –5V to 25V, VREF = 1.25V
60
72
dB
VS = 5V, 0V
VCM = –5V to 80V, VREF = 1.25V
60
72
dB
VS = 5V, 0V (Note 6)
VCM = –38V to 47V, VREF = 2.5V
60
VOS
Offset Voltage, RTI
25
80
47
72
0.8
Input Noise Voltage, RTI
fO = 0.1Hz to 10Hz
%
dB
3
mV
30
µVP-P
1
µV/√Hz
en
Noise Voltage Density, RTI
fO = 1kHz
RIN
Input Resistance
Differential
Common Mode
PSRR
Power Supply Rejection Ratio, RTI
VS = 2.7V to 12.7V, VCM = VREF = 1.25V
Minimum Supply Voltage
Guaranteed by PSRR
2.4
2.7
2
0.5
80
V
V
V
MΩ
MΩ
92
dB
V
IS
Supply Current
(Note 7)
160
180
µA
VOL
Output Voltage Swing LOW
–IN = V+, +IN = Half Supply (Note 7)
20
50
mV
VOH
Output Voltage Swing HIGH
–IN = 0V, +IN = Half Supply
VS = 3V, 0V, Below V+
VS = 5V, 0V, Below V+
80
100
150
175
mV
mV
ISC
Output Short-Circuit Current
Short to GND (Note 8)
Short to V+ (Note 8)
BW
Bandwidth (–3dB)
SR
Slew Rate
VS = 5V, 0V, VOUT = 0.5V to 4.5V
Settling Time to 0.01%
4V Output Step, VS = 5V, 0V
AVREF
Reference Gain to Output
4
13
8
20
mA
mA
100
kHz
1
V/µs
20
µs
1 ± 0.007
Rev 0
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3
LT1990-10
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the temperature range of
–40°C ≤ TA ≤ 85°C. VS = V+, V–; VS = 3V, 0V; VS = 5V, 0V; RL = 10kΩ, VCM = VREF = half supply, unless otherwise noted. (Note 4)
SYMBOL PARAMETER
CONDITIONS
∆G
Gain Error
VOUT = 0.5V to (+VS) – 0.75V
l
∆G/∆T
Gain vs Temperature
(Note 9)
l
VCM
Input Voltage Range
Guaranteed by CMRR
VS = 3V, 0V; VREF = 1.25V
VS = 5V, 0V; VREF = 1.25V
VS = 5V, 0V; VREF = 2.5V
l
l
l
–5
–5
–38
VS = 3V, 0V (Note 6)
VCM = –5V to 25V, VREF = 1.25V
l
57
dB
VS = 3V, 0V
VCM = –5V to 80V, VREF = 1.25V
l
57
dB
VS = 5V, 0V (Note 6)
VCM = –38V to 47V, VREF = 2.5V
l
57
dB
CMRR
Common Mode Rejection Ratio
RTI (Referred to Input)
MIN
TYP
MAX
0.95
7
%
20
ppm/°C
25
80
47
V
V
V
VOS
Offset Voltage, RTI
∆VOS/∆T
Input Offset Voltage Drift, RTI
(Note 9)
l
5
VOSH
Input Offset Voltage Hysteresis, RTI
(Note 10)
l
230
PSRR
Power Supply Rejection Ratio, RTI
VS = 2.7V to 12.7V, VCM = VREF = 1.25V
l
Minimum Supply Voltage
Guaranteed by PSRR
l
2.7
l
UNITS
4.5
mV
22
µV/°C
µV
76
dB
V
IS
Supply Current
(Note 7)
l
250
µA
VOL
Output Voltage Swing LOW
–IN = V+, +IN = Half Supply (Note 7)
l
70
mV
VOH
Output Voltage Swing HIGH
–IN = 0V, +IN = Half Supply
VS = 3V, 0V, Below V+
VS = 5V, 0V, Below V+
l
l
200
225
mV
mV
Short to GND (Note 8)
Short to V+ (Note 8)
l
l
ISC
Output Short-Circuit Current
2
8
mA
mA
Rev 0
4
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LT1990-10
±15V ELECTRICAL CHARACTERISTICS
VS = ±15V, RL = 10kΩ, VCM = VREF = 0V, TA = 25°C, unless
otherwise noted.
SYMBOL PARAMETER
G
Gain
∆G
Gain Error
CONDITIONS
MIN
Gain Nonlinearity
VOUT = ±10V
VCM
Input Voltage Range
Guaranteed by CMRR
-250
CMRR
Common Mode Rejection Ratio, RTI
VCM = –250V to 250V
60
VOS
Offset Voltage, RTI
fO = 0.1Hz to 10Hz
en
Noise Voltage Density, RTI
fO = 1kHz
RIN
Input Resistance
Differential
Common Mode
PSRR
Power Supply Rejection Ratio, RTI
VS = ±1.35V to ±18V, VCM = VREF = 1.25V
Minimum Supply Voltage
Guaranteed by PSRR
VOUT
Output Voltage Swing
ISC
Output Short-Circuit Current
UNITS
0.2
0.8
%
0.005
0.02
%
250
V
72
0.9
Input Noise Voltage, RTI
Supply Current
MAX
10
VOUT = ±10V
GNL
IS
TYP
1
µV/√Hz
2
0.5
82
100
V
200
275
µA
9
22
0.8
VOUT = ±10V, No RL
Settling Time to 0.01%
10V Output Step
AVREF
Reference Gain to Output
dB
±1.35
±14.75
Bandwidth (–3dB)
MΩ
MΩ
±1.2
6
15
Slew Rate
mV
µVP-P
±14.5
BW
5.2
30
Short to VShort to V+
SR
dB
V
mA
mA
110
kHz
1.2
V/µs
25
µs
1 ± 0.007
Rev 0
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5
LT1990-10
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the temperature range of
-40°C ≤ TA ≤ 85°C. VS = ±15V, RL = 10kΩ, VCM = VREF = 0V, unless otherwise noted. (Note 4)
SYMBOL PARAMETER
CONDITIONS
MAX
UNITS
VOUT = ±10V
l
∆G
Gain Error
GNL
Gain Nonlinearity
∆G/∆T
VCM
MIN
TYP
0.95
%
VOUT = ±10V
l
0.03
%
Gain vs Temperature
(Note 9)
l
Input Voltage Range
Guaranteed by CMRR
l
-250
CMRR
Common Mode Rejection Ratio, RTI
VCM = –250V to 250V
l
58
VOS
Offset Voltage, RTI
∆VOS/∆T
Input Offset Voltage Drift, RTI
7
l
VOSH
Input Offset Voltage Hysteresis, RTI
(Note 10)
l
PSRR
Power Supply Rejection Ratio, RTI
VS = ±1.35V to ±18V, VCM = VREF = 1.25V
l
Minimum Supply Voltage
Guaranteed by PSRR
l
ppm/°C
V
dB
l
(Note 9)
20
250
5
6.7
mV
22
µV/°C
250
µV
78
IS
Supply Current
l
VOUT
Output Voltage Swing
l
±14.3
dB
±1.35
V
375
µA
V
ISC
Output Short-Circuit Current
Short to V-
Short to V+
l
l
3
10
mA
mA
SR
Slew Rate
VOUT = ±10V, No RL
l
0.4
V/µs
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: ESD (Electrostatic Discharge) sensitive device. Extensive use of
ESD protection devices are used internal to the LT1990-10, however, high
electrostatic discharge can damage or degrade the device. Use proper ESD
handling precautions.
Note 3: A heat sink may be required to keep the junction temperature
below absolute maximum.
Note 4: The LT1990I-10 is designed, characterized and expected to be
functional over the operating temperature range of – 55°C to 125°C, but is
not tested or QA sampled at these temperatures.
Note 5: The LT1990I-10 is guaranteed to meet specified performance from
–40°C to 85°C.
Note 6: Limits are guaranteed by correlation to –5V to 80V CMRR tests.
Note 7: VS = 3V limits are guaranteed by correlation to VS = 5V and
VS = ±15V tests.
Note 8: VS = 5V limits are guaranteed by correlation to VS = 3V and
VS = ±15V tests.
Note 9: This parameter is not 100% tested.
Note 10: Hysteresis in offset voltage is created by package stress that
differs depending on whether the IC was previously at a higher or lower
temperature. Offset voltage hysteresis is always measured at 25°C, but the
IC is cycled to 85°C or –40°C before successive measurement.
Rev 0
6
For more information www.analog.com
LT1990-10
TYPICAL PERFORMANCE CHARACTERISTICS
Supply Current
vs Supply Voltage
300
TA = 125°C
TA = 85°C
TA = 25°C
TA = –40°C
TA = –55°C
50
5
0
10 15 20 25 30
SUPPLY VOLTAGE (V)
200
150
100
0
–50
40
35
0
25
50
75
TEMPERATURE (°C)
–25
1990 G01
TA = 125°C
TA = 25°C
TA = –55°C
0.01
0.1
1
10
OUTPUT CURRENT (mA)
100
VS = ±2.5V
NO LOAD
–0.01
0
6
8
10 12
4
SUPPLY VOLTAGE (±V)
14
OUTPUT VOLTAGE SWING
WITH RESPECT TO V+ (V)
OUTPUT VOLTAGE SWING
WITH RESPECT TO V – (V)
16
TA = 125°C
TA = 25°C
TA = –55°C
0.1
0.01
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
DIFFERENTIAL INPUT VOLTAGE (±V)
VS = ±2.5V
NO LOAD
0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
DIFFERENTIAL INPUT VOLTAGE (±V)
1990 G05
1
VIN+ = V+/10
100
1
1990 G06
Output Voltage Swing vs Supply
Voltage (Low)
VIN+ = 2V
0.01
0.1
1
10
OUTPUT CURRENT (mA)
1990 G03
10
–0.1
TA = 25°C
VIN–= 0V
NO LOAD
2
– 0.01
0.001
TA = 125°C
TA = 25°C
TA = –55°C
–1
Output Voltage Swing
vs Supply Voltage (High)
0
TA = 125°C
TA = 25°C
TA = –55°C
Output Voltage Swing
vs Input Voltage (Low)
1990 G04
–0.1
125
OUTPUT VOLTAGE SWING
WITH RESPECT TO V– (V)
0.1
OUTPUT VOLTAGE SWING
WITH RESPECT TO V+ (V)
OUTPUT VOLTAGE SWING
WITH RESPECT TO V– (V)
–10
1
–1
100
Output Voltage Swing
vs Input Voltage (High)
VS = ±2.5V
–IN = 0V
+IN = –2.5V
0.01
0.001
– 0.1
1990 G02
Output Voltage Swing
vs Load Current (Sink)
10
–1
50
Output Short-Circuit Current
vs Supply Voltage
20
TA = 25°C
VIN– = 0V
NO LOAD
OUTPUT SHORT-CIRCUIT CURRENT (mA)
100
OUTPUT VOLTAGE SWING
WITH RESPECT TO V+ (V)
SUPPLY CURRENT (µA)
150
–0.01
VS = ±2.5V
–IN = 0V
+IN = 2.5V
VS = 5V, 0V
250
200
0
Output Voltage Swing
vs Load Current (Source)
– 10
300
VREF = VOUT = 1.25V
V – = 0V
250
SUPPLY CURRENT (µA)
Supply Current
vs Temperature
VIN+ = V –/10
0.1
VIN+ = –2V
0.01
0
2
10 12
8
4
6
SUPPLY VOLTAGE (±V)
14
16
15 SOURCE
10
TA = –55°C
TA = 25°C
5
TA = 125°C
0
–5
–10
TA = 125°C
–15
TA = –55°C
–20
SINK
–25
–30
0
2
TA = 25°C
4
6
8
10 12
SUPPLY VOLTAGE (±V)
14
16
199010 G09
1990 G08
1990 G07
Rev 0
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7
LT1990-10
TYPICAL PERFORMANCE CHARACTERISTICS
Input Voltage Range
vs Split Supply Voltage
300
V – = 0V
TA = –40°C TO 85°C
VREF = 4V
VREF = 1.25V
100
VREF = 2.5V
50
VREF = 1.25V
0
VREF = 2.5V
–50
–100
VREF = 4V
3
7
9
11
13
5
POSITIVE SUPPLY VOLTAGE (V)
200
100
0
–100
–200
–300
15
1
9
7
11
5
SUPPLY VOLTAGE (V)
3
13
1990 G10
20
10
130
FREQUENCY (kHz)
GAIN (dB)
0
–10
–20
–30
90
70
10k
100k
FREQUENCY (Hz)
1M
60
10M
1k
VS = ±15V
TA = 25°C
OUTPUT IMPEDANCE (Ω)
SLEW RATE (V/µS)
1.8
1.6
1.4
1.2
1.0
0.8
TA = 125°C
TA = 85°C
TA = 25°C
TA = –40°C
TA = –55°C
2
0
8
6
10 12
4
SUPPLY VOLTAGE (±V)
0
25
50
75
TEMPERATURE (°C)
100
125
TA = 25°C
NO LOAD
14
1.0
0.8
0.6
0.4
+SR
–SR
0.2
0
16
0
2
4
6
8
10 12
SUPPLY VOLTAGE (±V)
14
1990 G15
100
100
10
1
100
RL = 10k
NO LOAD
1k
10k
100k
FREQUENCY (Hz)
1M
1990 G17
1990 G16
16
Power Supply Rejection Ratio
vs Frequency
VS = 5V, 0V
TA = 25°C
+SR
–SR
0.6
1M
10k
100k
FREQUENCY(Hz)
1.2
Output Impedance vs Frequency
2.0
1k
1990 G14
Slew Rate vs Temperature
–25
10
1.4
1990 G13
0.4
–50
20
1.6
100
–50
2.2
30
Slew Rate vs Supply Voltage
110
80
2.4
40
1.8
120
–40
1k
50
1990 G12
160
TA = 25°V
150 V OUT = HALF SUPPLY
NO LOAD
140
–60
100
60
–3dB Bandwidth
vs Supply Voltage
VS = 5V, 0V
TA = 25°C
30
70
1990 G11
Gain vs Frequency
40
VS = 5V, 0V
90 TA = 25°C
REFERRED TO INPUT
80
0
100
15
SLEW RATE (V/µS)
150
100
VREF = 0V
TA = –40°C TO 85°C
POWER SUPPLY REJECTION RATIO (dB)
200
MAXIMUM INPUT VOLTAGE (V)
MAXIMUM INPUT VOLTAGE (V)
250
Common Mode Rejection Ratio
vs Frequency
COMMON MODE REJECTION RATIO (dB)
Input Voltage Range
vs Single Supply Voltage
VS = 5V, 0V
TA = 25°C
REFERRED TO INPUT
90
80
70
60
50
40
30
20
10
0
100
NEGATIVE SUPPLY
POSITIVE SUPPLY
1k
10k
100k
FREQUENCY (Hz)
1M
1990 G18
Rev 0
8
For more information www.analog.com
LT1990-10
TYPICAL PERFORMANCE CHARACTERISTICS
30
20
10
0
–10
10000
VS = ±15V
RL = 10k
25
0.01% OF
STEP
0.01% OF
STEP
20
0.1% OF
STEP
15
0.1% OF
STEP
10
–20
–30
30
VS = ±15V
TA = 25°C
REFERRED TO INPUT
SETTLING TIME (µS)
CHANGE IN OFFSET VOLTAGE (µV)
40
Voltage Noise Density
vs Frequency
Settling Time vs Output Step
VOLTAGE NOISE DENSITY (nV/√Hz)
Warm–up Drift
0
10
20
30
40
50
TIME AFTER POWER–UP (S)
5
–10 –8 –6 –4 –2 0 2 4
OUTPUT STEP (V)
60
6
8
1000
100
10
1
10
100
1k
FREQUENCY (Hz)
0.1Hz to 10Hz Noise Voltage
1990 G21
0.01Hz to 1Hz Noise Voltage
VS = ±1.5V TO ±15V
TA = 25°C
REFERRED TO INPUT
Overshoot vs Capacitive Load
60
50
OVERSHOOT (%)
NOISE VOLTAGE (10µV/DIV)
VS = ±1.5V TO ±15V
TA = 25°C
REFERRED TO INPUT
VOUT = ±50mV
RL = 10k
40
30
20
10
0
1
2
3
4 5 6
TIME (S)
7
8
9
0
10
0
10 20 30 40 50 60 70 80 90 100
TIME (S)
VS = ±15V
VS = 3V, 0V
1000
100
CAPACITIVE LOAD (pF)
10
199010 G23
Instability with
Output Saturated to V+
Small Signal Transient Response
Small Signal Transient Response
1400
VS = 3V, 0V
RL = 10k
VREF = 1.5V
UNSTABLE
VS = ±15V
RL=10k
VREF=GND
STABLE
800
600
STABLE ILOAD = 1mA
ILOAD = 2mA
ILOAD = 3mA
ILOAD = 4mA
STABLE ILOAD = 5mA
400
200
0
50mV/DIV
1000
50mV/DIV
CAPACITIVE LOAD (pF)
10000
1990 G24
1990 G22
1200
10k
1990 G20
1990 G19
NOISE VOLTAGE (10µV/DIV)
VS = ±1.5V TO ±15V
T A = 25°C
REFERRED TO INPUT
0
5
10
15
20
SUPPLY VOLTAGE (V)
25
30
50µs/DIV
50µs/DIV
1990 G26
199010 G27
1990 G25
Rev 0
For more information www.analog.com
9
LT1990-10
TYPICAL PERFORMANCE CHARACTERISTICS
INPUT VOLTAGE (V)
VS = ±15V
RL = 10k
VREF = GND
15
5
–5
–15
5V/DIV
VS = ±15V
VREF = GND
NO LOAD
20
10
0
–10
–20
50µs/DIV
50µs/DIV
1990 G28
OUTPUT VOLTAGE (V)
5V/DIV
Input Common Mode Voltage
Transient Response
Large Signal Transient Response
Large Signal Transient Response
20µs/DIV
1990 G29
1990 G30
PIN FUNCTIONS
REF: Reference Input. Sets the output level when the difference between the inputs is zero.
–IN: Inverting Input. Connects a 1MΩ resistor divider
to the op amp’s inverting input. Designed to permit high
voltage operation.
+IN: Noninverting Input. Connects a 1MΩ resistor divider
to the op amp’s noninverting input. Designed to permit
high voltage operation.
V–: Negative Power Supply. Can be either ground (in single
supply applications) or a negative voltage (in split supply
applications).
NC: Not internally connected. May be tied to any pin or
floated.
OUT: Output. VOUT = 10 • (V+IN – V–IN) + VREF.
V+: Positive Power Supply. Can range from 2.7V to 36V
above the V– voltage.
Rev 0
10
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LT1990-10
BLOCK DIAGRAM
V+
R5
900k
–IN
R1
1M
+IN
R2
1M
R7
10k
NC
R6
100k
–
OUT
+
R8
900k
R3
40k
R4
40k
REF
R10
10k
R9
100k
NC
V–
199010 SS
Rev 0
For more information www.analog.com
11
LT1990-10
APPLICATIONS INFORMATION
Primary Features
The LT1990-10 is a complete gain-block solution for
high input common mode voltage applications. The part
combines a low-power precision operational amplifier
with thin-film resistors trimmed to produce a gain of 10
with high accuracy. The Block Diagram shows the internal architecture of the part. The on-chip resistors form a
modified difference-amplifier including a reference port for
introducing offset or other additive waveforms. The resistor
network is structured to produce internal common mode
voltage division of 27, enabling a very large input range.
The input range can far exceed the power supply voltage(s)
used by the LT1990-10 itself. Standard ESD clamp diodes
are included on all the I/O except the –IN and +IN pins.
The inputs are rated to ±250V and protected to ±500V. The
LT1990-10 is ideally suited to situations where relatively
small signals need to be extracted from high voltage circuits,
as is the case in many instrumentation applications. With its
wide input voltage range and greater than 1 megohm input
impedances, development of instrumentation designs is
greatly simplified with the LT1990-10 single-chip solution
over conventional discrete methods.
Classic Difference Amplifier
The basic gain of ten difference amplifier topology has the
following dc transfer function:
VO = 10·(V+IN – V–IN) + VREF
By including the internal common mode division by 27,
the input common mode range capability is extended up
to ±250V according to the following relationships:
VCM+ ≤ 27 • V+ – 26 • VREF – 23
VCM– ≥ 27 • V– – 26 • VREF + 27
For split supplies over about ±11V, the full ±250V common
mode range is normally available (with VREF a small fraction
of the supply). With lower supply voltages, an appropriate
selection of VREF can tailor the input common mode range
to a specific requirement. For single supply circuits, VREF
should be greater than V– to allow bidirectional output
swing and to keep the inputs of the internal op amp within
their operating region. Note: the differential input voltage
range is reduced as VCM approaches its limits. The following low supply-voltage scenarios are readily implemented
with the LT1990-10:
Table 1.
Supply
VREF
VCM Range
3V
1.25V
–5V to 25V (e.g. 12V Automotive Environment)
5V
1.25V
–5V to 80V (e.g. 42V Automotive Environment)
5V
4.00V
–77V to 8V (e.g. Telecom Environment;
Use Downward Signaling)
Preserving and Enhancing Common Mode Rejection
The basic difference amplifier topology of the LT1990-10 is
sensitive to the external resistances of circuits driving the
part. To preserve the high accuracy of the LT1990-10, the
source impedance of any signal connected to the REF pin
must be on the order of a few ohms or less, such as from
a Reference or op-amp output. The difference inputs have
nominal 1 megohm internal resistances that are matched
to within a few hundred ohms, so source resistances
should also be kept low to maximize accuracy and CMRR.
While every LT1990-10 is factory trimmed, some precision
applications with a large applied common mode voltage
may benefit from a trim method to further minimize common mode error. This is easily accomplished as shown in
Figure 1. A series resistance is added to each input: a fixed
1kΩ in series with one of the inputs and a 2kΩ trimmer
Rev 0
12
For more information www.analog.com
LT1990-10
APPLICATIONS INFORMATION
in series with the other. The trim range of this configuration is ±0.1% for the internal input resistor matching.
This technique using the LT1990-10 offers a much more
finely resolved correction than is available from ordinary
discrete solutions. In applications where the common mode
is relatively constant and large, this same configuration
can be treated as an offset adjustment.
1k
2k
–
LT1990-10
+
Output Stability with Capacitive Loads
The LT1990-10 is internally compensated to drive high
capacitive loads of at least 2nF under all output loading conditions when the output is in its linear region or
saturated to V–. However, a small oscillation may occur if
the output is saturated to V+ with capacitive loads greater
than 300pF at higher load currents and higher supply
voltages. A 10nF capacitor in series with a 600Ω resistor
placed between the output and ground will compensate
the amplifier for capacitive loads up to 10nF at all output
loading conditions. See the region of instability in the
Typical Performance Characteristics section.
199010 F01
Figure 1. Optional CMRR Trim
Rev 0
For more information www.analog.com
13
LT1990-10
PACKAGE DESCRIPTION
MS8 Package
8-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1660 Rev G)
0.889 ±0.127
(.035 ±.005)
5.10
(.201)
MIN
3.20 – 3.45
(.126 – .136)
3.00 ±0.102
(.118 ±.004)
(NOTE 3)
0.65
(.0256)
BSC
0.42 ± 0.038
(.0165 ±.0015)
TYP
8
7 6 5
0.52
(.0205)
REF
RECOMMENDED SOLDER PAD LAYOUT
0.254
(.010)
3.00 ±0.102
(.118 ±.004)
(NOTE 4)
4.90 ±0.152
(.193 ±.006)
DETAIL “A”
0° – 6° TYP
GAUGE PLANE
0.53 ±0.152
(.021 ±.006)
DETAIL “A”
1
2 3
4
1.10
(.043)
MAX
0.86
(.034)
REF
0.18
(.007)
SEATING
PLANE
0.22 – 0.38
(.009 – .015)
TYP
0.65
(.0256)
BSC
0.1016 ±0.0508
(.004 ±.002)
MSOP (MS8) 0213 REV G
NOTE:
1. DIMENSIONS IN MILLIMETER/(INCH)
2. DRAWING NOT TO SCALE
3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX
Rev 0
14
For more information www.analog.com
LT1990-10
PACKAGE DESCRIPTION
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610 Rev G)
.050 BSC
.189 – .197
(4.801 – 5.004)
NOTE 3
.045 ±.005
8
.245
MIN
.160 ±.005
.010 – .020
× 45°
(0.254 – 0.508)
NOTE:
1. DIMENSIONS IN
5
.150 – .157
(3.810 – 3.988)
NOTE 3
1
RECOMMENDED SOLDER PAD LAYOUT
.053 – .069
(1.346 – 1.752)
0°– 8° TYP
.016 – .050
(0.406 – 1.270)
6
.228 – .244
(5.791 – 6.197)
.030 ±.005
TYP
.008 – .010
(0.203 – 0.254)
7
.014 – .019
(0.355 – 0.483)
TYP
INCHES
(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)
4. PIN 1 CAN BE BEVEL EDGE OR A DIMPLE
2
3
4
.004 – .010
(0.101 – 0.254)
.050
(1.270)
BSC
SO8 REV G 0212
Rev 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog
Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications
subject to change without notice. No license For
is granted
implication or
otherwise under any patent or patent rights of Analog Devices.
more by
information
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15
LT1990-10
TYPICAL APPLICATIONS
Telecom Supply Current Monitor
+
LOAD
IL
Boosted Bidirectional Controlled Current Source
+V
5V
48V
–
1k
+
RS
VOUT
LT1990-10
–77V ≤ VCM ≤ 8V
VOUT = VREF – (10 • IL • RS)
LT1990-10
REF
IN
OUT
LT6650
GND FB
+
VCTL
–
CZT751
–
VREF = 4V
+
10µF
RSENSE
REF
ILOAD
1nF
174k
1k
CZT651
20k
–V
199010 TA02
ILOAD = 10 • VCTL/RSENSE ≤ 100mA
EXAMPLE: FOR RSENSE =100 ,
OUTPUT IS 1mA PER 10mV INPUT
1µF
199010 TA03
Bidirectional Controlled Current Source
+V
VCTL
+
LT1990-10
–
REF
RSENSE
–V
ILOAD
ILOAD = 10 • VCTL/RSENSE ≤ 3mA
EXAMPLE: FOR RSENSE =1k,
OUTPUT IS 1mA PER 100mV INPUT
199010 TA04
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±160V Input Voltage Range, Pin Selectable G = –13 to 14
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97dB Minimum CMRR, Over the Top Protected Inputs
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±230V Common Mode Voltage Difference Amplifier G = 10
90dB Minimum CMRR, Over the Top Protected Inputs
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Three Gain Options, –5V to 80V Input Common Mode Voltage Range
Rev 0
16
D17017-0-6/18(0)
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