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LT1990
1
1990f
Battery Cell Voltage Monitoring
High Voltage Current Sensing
Signal Acquisition in Noisy Environments
Input Protection
Fault Protected Front Ends
Level Sensing
Isolation
Pin Selectable Gain of 1 or 10
High Common Mode Voltage Range:
85V Window (V
S
= 5V, 0V)
250V (V
S
= 15V)
Common Mode Rejection Ratio: 70dB Min
Input Protection to 350V
Gain Error: 0.28% Max
PSRR: 82dB Min
High Input Impedance: 2M Differential,
500k Common Mode
Micropower: 120A Max Supply Current
Wide Supply Range: 2.7V to 36V
3dB Bandwidth: 100kHz
Rail-to-Rail Output
8-Pin SO Package
250V Input Range
G = 1, 10, Micropower,
Difference Amplifier
The LT
1990 is a micropower precision difference ampli-
fier with a very high common mode input voltage range. It
has pin selectable gains of 1 or 10. The LT1990 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 is ideally suited for both
high side and low side current or voltage monitoring.
On a single 5V supply, the LT1990 has an adjustable 85V
input range, 70dB min CMRR and draws less than 120A
supply current. The rail-to-rail output maximizes the dy-
namic range, especially important for single supplies as
low as 2.7V.
The LT1990 is specified for single 3V, 5V and 15V
supplies over both commercial and industrial temperature
ranges. The LT1990 is available in the 8-pin SO package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Full-Bridge Load Current Monitor
R
S
+V
SOURCE
I
L
12V V
CM
73V
V
OUT
= V
REF
(10 I
L
R
S
)
+
40k
40k
100k
100k
900k
1M
1M
900k
10k
10k
V
OUT
LT1990
LT6650
GND
IN
OUT
FB
54.9k
20k
1nF
1F
V
REF
= 1.5V
1990 TA01
5V
7
2
3
4
1
8
6
5
+
APPLICATIO S
U
DESCRIPTIO
U
FEATURES
TYPICAL APPLICATIO
U
LT1990
2
1990f
Total Supply Voltage (V
+
to V
) ............................... 36V
Input Voltage Range
Continuous ...................................................... 250V
Transient (0.1s) ............................................... 350V
Differential ....................................................... 500V
Output Short-Circuit Duration (Note 3) ............ Indefinite
Operating Temperature Range (Note 4) ...40C to 85C
Specified Temperature Range (Note 5) ....40C to 85C
Storage Temperature Range .................. 65C to 150C
Lead Temperature (Soldering, 10 sec.)................. 300C
ORDER PART
NUMBER
T
JMAX
= 150C,
JA
= 190C/W
1990
1990A
1990I
1990AI
LT1990CS8
LT1990IS8
LT1990ACS8
LT1990AIS8
ABSOLUTE AXI U
RATI GS
W
W
W
U
PACKAGE/ORDER I FOR ATIO
U
U
W
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
G
Gain
Pins 5 and 8 = Open
1
Pins 5 and 8 = GND
10
G
Gain Error
V
OUT
= 0.5V to (+Vs) 0.75V
LT1990, G = 1
0.4
0.6
%
LT1990A, G = 1
0.07
0.28
%
G = 10, V
S
= 5V, 0V
0.2
0.8
%
GNL
Gain Nonlinearity
V
S
= 5V, 0V; V
OUT
= 0.5V to 4.25V
G = 1
0.001
0.005
%
G = 10
0.01
%
V
CM
Input Voltage Range
Guaranteed by CMRR
V
S
= 3V, 0V; V
REF
= 1.25V
5
25
V
V
S
= 5V, 0V; V
REF
= 1.25V
5
80
V
V
S
= 5V, 0V; V
REF
= 2.5V
38
47
V
CMRR
Common Mode Rejection Ratio
V
S
= 3V, 0V (Note 7)
RTI (Referred to Input)
V
CM
= 5V to 25V, V
REF
= 1.25V
LT1990
60
68
dB
LT1990A
70
75
dB
V
S
= 5V, 0V
V
CM
= 5V to 80V, V
REF
= 1.25V
LT1990
60
68
dB
LT1990A
70
75
dB
V
S
= 5V, 0V (Note 7)
V
CM
= 38V to 47V, V
REF
= 2.5V
LT1990
60
68
dB
LT1990A
70
75
dB
V
OS
Offset Voltage, RTI
G = 1, 10
0.8
3
mV
e
n
Input Noise Voltage, RTI
f
O
= 0.1Hz to 10Hz
22
V
P-P
Noise Voltage Density, RTI
f
O
= 1kHz
1
V/Hz
3V/5V ELECTRICAL CHARACTERISTICS
V
S
= 3V, 0V; V
S
= 5V, 0V; R
L
= 10k, V
CM
= V
REF
= half supply, G = 1, 10, T
A
= 25C, unless otherwise noted. (Note 6)
S8 PART
MARKING
TOP VIEW
GAIN1
V
+
OUT
GAIN2
REF
IN
+IN
V
S8 PACKAGE
8-LEAD PLASTIC SO
1
2
3
4
8
7
6
5
(Notes 1, 2)
LT1990
3
1990f
3V/5V ELECTRICAL CHARACTERISTICS
V
S
= 3V, 0V; V
S
= 5V, 0V; R
L
= 10k, V
CM
= V
REF
= half supply, G = 1, 10, T
A
= 25C, unless otherwise noted. (Note 6)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
R
IN
Input Resistance
Differential
2
M
Common Mode
0.5
M
PSRR
Power Supply Rejection Ratio, RTI
V
S
= 2.7V to 12.7V, V
CM
= V
REF
= 1.25V
80
92
dB
Minimum Supply Voltage
Guaranteed by PSRR
2.4
2.7
V
I
S
Supply Current
(Note 8)
105
120
A
V
OL
Output Voltage Swing LOW
IN = V
+
,
+IN = Half Supply (Note 8)
30
50
mV
V
OH
Output Voltage Swing HIGH
IN = 0V,
+IN = Half Supply
V
S
= 3V, 0V, Below V
+
100
150
mV
V
S
= 5V, 0V, Below V
+
120
175
mV
I
SC
Output Short-Circuit Current
Short to GND (Note 9)
4
8
mA
Short to V
+
(Note 9)
13
20
mA
BW
Bandwidth (3dB)
G = 1
100
kHz
G = 10
6.5
kHz
SR
Slew Rate
G = 1, V
S
= 5V, 0V, V
OUT
= 0.5V to 4.5V
0.5
V/s
Settling Time to 0.01%
4V Step, G = 1, V
S
= 5V, 0V
45
s
AV
REF
Reference Gain to Output
1 0.0007
The
denotes the specifications which apply over the temperature range of 0
C
T
A
70
C. V
S
= 3V, 0V; V
S
= 5V, 0V; R
L
= 10k,
V
CM
= V
REF
= half supply, G = 1, 10, unless otherwise noted. (Notes 4, 6)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
G
Gain Error
V
OUT
= 0.5V to (+V
S
) 0.75V
LT1990, G = 1
0.65
%
LT1990A, G = 1
0.33
%
G = 10
0.90
%
G/T
Gain vs Temperature
G = 1 (Note 10)
2
10
ppm/C
G = 10 (Note 10)
7
20
ppm/C
V
CM
Input Voltage Range
Guaranteed by CMRR
V
S
= 3V, 0V, V
REF
= 1.25V
5
25
V
V
S
= 5V, 0V, V
REF
= 1.25V
5
80
V
V
S
= 5V, 0V, V
REF
= 2.5V
37
48
V
CMRR
Common Mode Rejection Ratio, RTI
V
S
= 3V, 0V (Note 7)
V
CM
= 5V to 25V, V
REF
= 1.25V
LT1990
58
dB
LT1990A
68
dB
V
S
= 5V, 0V
V
CM
= 5V to 80V, V
REF
= 1.25V
LT1990
58
dB
LT1990A
68
dB
V
S
= 5V, 0V (Note 7)
V
CM
= 38V to 47V, V
REF
= 2.5V
LT1990
58
dB
LT1990A
68
dB
V
OS
Input Offset Voltage, RTI
V
S
= 3V, 0V
G = 1, 10
4.1
mV
V
S
= 5V, 0V
G = 1, 10
4.1
mV
LT1990
4
1990f
3V/5V ELECTRICAL CHARACTERISTICS
The
denotes the specifications which apply over the temperature range of 0
C
T
A
70
C. V
S
= 3V, 0V; V
S
= 5V, 0V; R
L
= 10k,
V
CM
= V
REF
= half supply, G = 1, 10, unless otherwise noted. (Notes 4, 6)
The
denotes the specifications which apply over the temperature range of 40C T
A
85C. V
S
= 3V, 0V; V
S
= 5V, 0V; R
L
= 10k,
V
CM
= V
REF
= half supply, G = 1, 10, unless otherwise noted. (Notes 4, 6)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
G
Gain Error
V
OUT
= 0.5V to (+V
S
) 0.75V
LT1990, G = 1
0.67
%
LT1990A, G = 1
0.35
%
G = 10
0.95
%
G/T
Gain vs Temperature
G = 1 (Note 10)
2
10
ppm/C
G = 10 (Note 10)
7
20
ppm/C
V
CM
Input Voltage Range
Guaranteed by CMRR
V
S
= 3V, 0V, V
REF
= 1.25V
5
25
V
V
S
= 5V, 0V, V
REF
= 1.25V
5
80
V
V
S
= 5V, 0V, V
REF
= 2.5V
37
48
V
CMRR
Common Mode Rejection Ratio, RTI
V
S
= 3V, 0V (Note 7)
V
CM
= 5V to 25V, V
REF
= 1.25V
LT1990
57
dB
LT1990A
67
dB
V
S
= 5V, 0V
V
CM
= 5V to 80V, V
REF
= 1.25V
LT1990
57
dB
LT1990A
67
dB
V
S
= 5V, 0V (Note 7)
V
CM
= 38V to 47V, V
REF
= 2.5V
LT1990
57
dB
LT1990A
67
dB
V
OS
Input Offset Voltage, RTI
V
S
= 3V, 0V
G = 1, 10
4.5
mV
V
S
= 5V, 0V
G = 1, 10
4.5
mV
V
OS
/T
Input Offset Voltage Drift, RTI
(Note 10)
5
22
V/C
V
OSH
Input Offset Voltage Hysteresis, RTI
(Note 11)
230
V
PSRR
Power Supply Rejection Ratio, RTI
V
S
= 2.7V to 12.7V
V
CM
= V
REF
= 1.25V
76
dB
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
OS
/T
Input Offset Voltage Drift, RTI
(Note 10)
5
22
V/C
V
OSH
Input Offset Voltage Hysteresis, RTI
(Note 11)
230
V
PSRR
Power Supply Rejection Ratio, RTI
V
S
= 2.7V to 12.7V
V
CM
= V
REF
= 1.25V
G = 1, 10
78
dB
Minimum Supply Voltage
Guaranteed by PSRR
2.7
V
I
S
Supply Current
(Note 8)
150
A
V
OL
Output Voltage Swing LOW
IN = V
+
,
+IN = Half Supply (Note 8)
60
mV
V
OH
Output Voltage Swing HIGH
IN = 0V,
+IN = Half Supply
V
S
= 3V, 0V, Below V
+
180
mV
V
S
= 5V, 0V, Below V
+
205
mV
I
SC
Output Short-Circuit Current
Short to GND (Note 9)
3
mA
Short to V
+
(Note 9)
11
mA
LT1990
5
1990f
3V/5V ELECTRICAL CHARACTERISTICS
The
denotes the specifications which apply over the temperature range of 40C T
A
85C. V
S
= 3V, 0V; V
S
= 5V, 0V;
R
L
= 10k, V
CM
= V
REF
= half supply, G = 1, 10, unless otherwise noted. (Notes 4, 6)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Minimum Supply Voltage
Guaranteed by PSRR
2.7
V
I
S
Supply Current
(Note 8)
170
A
V
OL
Output Voltage Swing LOW
IN = V
+
,
+IN = Half Supply (Note 8)
70
mV
V
OH
Output Voltage Swing HIGH
IN = 0V,
+IN = Half Supply
V
S
= 3V, 0V, Below V
+
200
mV
V
S
= 5V, 0V, Below V
+
225
mV
I
SC
Output Short-Circuit Current
Short to GND (Note 9)
2
mA
Short to V
+
(Note 9)
8
mA
15V ELECTRICAL CHARACTERISTICS
V
S
= 15V, R
L
= 10k, V
CM
= V
REF
= 0V, G = 1, 10, T
A
= 25C, unless otherwise noted. (Note 6)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
G
Gain
Pins 5 and 8 = Open
1
Pins 5 and 8 = V
REF
10
G
Gain Error
V
OUT
= 10V
LT1990, G = 1
0.4
0.6
%
LT1990A, G = 1
0.07
0.28
%
G = 10
0.2
0.8
%
GNL
Gain Nonlinearity
V
OUT
= 10V
G = 1
0.0008
0.002
%
G = 10
0.005
0.02
%
V
CM
Input Voltage Range
Guaranteed by CMRR
250
250
V
CMRR
Common Mode Rejection Ratio, RTI
V
CM
= 250V to 250V
LT1990
60
68
dB
LT1990A
70
75
dB
V
OS
Offset Voltage, RTI
G = 1, 10
0.9
5.2
mV
e
n
Input Noise Voltage, RTI
f
O
= 0.1Hz to 10Hz
22
V
P-P
Noise Voltage Density, RTI
f
O
= 1kHz
1
V/Hz
R
IN
Input Resistance
Differential
2
M
Common Mode
0.5
M
PSRR
Power Supply Rejection Ratio, RTI
V
S
= 1.35V to 18V
82
100
dB
Minimum Supply Voltage
Guaranteed by PSRR
1.2
1.35
V
I
S
Supply Current
140
180
A
V
OUT
Output Voltage Swing
14.5
14.79
V
I
SC
Output Short-Circuit Current
Short to V
6
9
mA
Short to V
+
15
22
mA
BW
Bandwidth
G = 1
105
kHz
G = 10
7
kHz
SR
Slew Rate
G = 1, V
OUT
= 10V
0.3
0.55
V/s
Settling Time to 0.01%
10V Step, G = 1
60
s
AV
REF
Reference Gain to Output
1 0.0007
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