LT1990
1
1990fb
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: 120µA 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 120µA
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.
Full-Bridge Load Current Monitor
RS
+VSOURCE
IL
–12V VCM 73V
VOUT = VREF ± (10 • IL • RS)
+
40k
40k 100k
100k
900k
1M
1M
900k 10k
10k
VOUT
LT1990
LT6650
GND
IN OUT
FB
54.9k
20k
1nF
1µF
VREF = 1.5V
1990 TA01
5V
7
2
3
4
1
8
6
5
+
APPLICATIO S
U
DESCRIPTIO
U
FEATURES
TYPICAL APPLICATIO
U
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
LT1990
2
1990fb
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/
S8 PART MARKING
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
= 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
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)
LT1990C .............................................. –40°C to 85°C
LT1990I ............................................... –40°C to 85°C
LT1990H ........................................... –40°C to 125°C
Specified Temperature Range (Note 5)
LT1990C .............................................. –40°C to 85°C
LT1990I ............................................... –40°C to 85°C
LT1990H ........................................... –40°C to 125°C
Junction Temperature........................................... 150°C
Storage Temperature Range .................. 65°C to 150°C
Lead Temperature (Soldering, 10 sec.)................. 300°C
ORDER PART NUMBER
1990
1990I
1990H
1990A
1990AI
1990AH
LT1990CS8
LT1990IS8
LT1990HS8
LT1990ACS8
LT1990AIS8
LT1990AHS8
ABSOLUTE AXI U RATI GS
W
WW
U
PACKAGE/ORDER I FOR ATIO
UUW
3V/5V ELECTRICAL CHARACTERISTICS
VS = 3V, 0V; VS = 5V, 0V; RL = 10k, VCM = VREF = half supply, G = 1, 10, TA = 25°C, unless otherwise noted. (Note 6)
(Notes 1, 2)
Consult LTC Marketing for parts specified with wider operating temperature ranges.
T
JMAX
= 150°C, θ
JA
= 190°C/W
TOP VIEW
GAIN1
V
+
OUT
GAIN2
REF
–IN
+IN
V
S8 PACKAGE
8-LEAD PLASTIC SO
1
2
3
4
8
7
6
5
LT1990
3
1990fb
3V/5V ELECTRICAL CHARACTERISTICS
VS = 3V, 0V; VS = 5V, 0V; RL = 10k, VCM = VREF = half supply, G = 1, 10, TA = 25°C, unless otherwise noted. (Note 6)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
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 µV
P-P
Noise Voltage Density, RTI f
O
= 1kHz 1 µV/Hz
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 µA
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/µs
Settling Time to 0.01% 4V Step, G = 1, V
S
= 5V, 0V 45 µs
AV
REF
Reference Gain to Output G = 1 1 ± 0.0007
G = 10 1 ± 0.007
The denotes the specifications which apply over the temperature range of 0
°
C
TA
70
°
C. VS = 3V, 0V; VS = 5V, 0V; RL = 10k,
VCM = VREF = half supply, G = 1, 10, unless otherwise noted. (Notes 4, 6)
LT1990C/LT1990I
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
LT1990
4
1990fb
3V/5V ELECTRICAL CHARACTERISTICS
The denotes the specifications which apply over the temperature range of 0
°
C
TA
70
°
C. VS = 3V, 0V; VS = 5V, 0V; RL = 10k,
VCM = VREF = half supply, G = 1, 10, unless otherwise noted. (Notes 4, 6)
The denotes the specifications which apply over the temperature range of –40°C TA 85°C. VS = 3V, 0V; VS = 5V, 0V; RL = 10k,
VCM = VREF = half supply, G = 1, 10, unless otherwise noted. (Notes 4, 6)
LT1990C/LT1990I
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
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
V
OS
/T Input Offset Voltage Drift, RTI (Note 10) 522µV/°C
V
OSH
Input Offset Voltage Hysteresis, RTI (Note 11) 230 µV
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 µA
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) 3mA
Short to V
+
(Note 9) 11 mA
LT1990C/LT1990I
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
LT1990
5
1990fb
LT1990H
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
G Gain Error V
OUT
= 0.5V to (+V
S
) – 0.75V
LT1990, G = 1 0.69 %
LT1990A, G = 1 0.37 %
G = 10 0.97 %
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 56 dB
LT1990A 66 dB
V
S
= 5V, 0V
V
CM
= –5V to 80V, V
REF
= 1.25V
LT1990 56 dB
LT1990A 66 dB
V
S
= 5V, 0V (Note 7)
V
CM
= –38V to 47V, V
REF
= 2.5V
LT1990 56 dB
LT1990A 66 dB
3V/5V ELECTRICAL CHARACTERISTICS
The denotes the specifications which apply over the temperature range of –40°C TA 85°C. VS = 3V, 0V; VS = 5V, 0V;
RL = 10k, VCM = VREF = half supply, G = 1, 10, unless otherwise noted. (Notes 4, 6)
LT1990C/LT1990I
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
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) 522µV/°C
V
OSH
Input Offset Voltage Hysteresis, RTI (Note 11) 230 µV
PSRR Power Supply Rejection Ratio, RTI V
S
= 2.7V to 12.7V
V
CM
= V
REF
= 1.25V 76 dB
Minimum Supply Voltage Guaranteed by PSRR 2.7 V
I
S
Supply Current (Note 8) 170 µA
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
+
275 mV
I
SC
Output Short-Circuit Current Short to GND (Note 9) 2mA
Short to V
+
(Note 9) 8mA
The denotes the specifications which apply over the temperature range of –40°C TA 125°C. VS = 3V, 0V; VS = 5V, 0V; RL = 10k,
VCM = VREF = half supply, G = 1, 10, unless otherwise noted. (Notes 4, 6)
3V/5V ELECTRICAL CHARACTERISTICS
LT1990
6
1990fb
±15V ELECTRICAL CHARACTERISTICS
VS = ±15V, RL = 10k, VCM = VREF = 0V, G = 1, 10, TA = 25°C, 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 µV
P-P
Noise Voltage Density, RTI f
O
= 1kHz 1 µV/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 µA
V
OUT
Output Voltage Swing ±14.5 ±14.79 V
LT1990H
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
OS
Input Offset Voltage, RTI V
S
= 3V, 0V
G = 1, 10 5.2 mV
V
S
= 5V, 0V
G = 1, 10 5.2 mV
V
OS
/T Input Offset Voltage Drift, RTI (Note 10) 522µV/°C
V
OSH
Input Offset Voltage Hysteresis, RTI (Note 11) 250 µV
PSRR Power Supply Rejection Ratio, RTI V
S
= 2.7V to 12.7V
V
CM
= V
REF
= 1.25V 75 dB
Minimum Supply Voltage Guaranteed by PSRR 2.7 V
I
S
Supply Current (Note 8) 200 µA
V
OL
Output Voltage Swing LOW –IN = V
+
,
+IN = Half Supply (Note 8) 80 mV
V
OH
Output Voltage Swing HIGH –IN = 0V,
+IN = Half Supply
V
S
= 3V, 0V, Below V
+
230 mV
V
S
= 5V, 0V, Below V
+
275 mV
I
SC
Output Short-Circuit Current Short to GND (Note 9) 1mA
Short to V
+
(Note 9) 5mA
The denotes the specifications which apply over the temperature range of –40°C TA 125°C. VS = 3V, 0V; VS = 5V, 0V; RL = 10k,
VCM = VREF = half supply, G = 1, 10, unless otherwise noted. (Notes 4, 6)
3V/5V ELECTRICAL CHARACTERISTICS
LT1990
7
1990fb
LT1990C/LT1990I
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
G Gain Error V
OUT
= ±10V
LT1990, G = 1 0.65 %
LT1990A, G = 1 0.33 %
G = 10 0.9 %
GNL Gain Nonlinearity V
OUT
= ±10V
G = 1 0.0025 %
G = 10 0.025 %
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 –250 250 V
CMRR Common Mode Rejection Ratio, RTI V
CM
= –250V to 250V
LT1990 59 dB
LT1990A 68 dB
V
OS
Input Offset Voltage, RTI G = 1, 10 6.2 mV
V
OS
/T Input Offset Voltage Drift, RTI (Note 10) 522µV/°C
V
OSH
Input Offset Voltage Hysteresis, RTI (Note 11) 250 µV
PSRR Power Supply Rejection Ratio, RTI V
S
= ±1.35V to ±18V 80 dB
Minimum Supply Voltage Guaranteed by PSRR ±1.35 V
I
S
Supply Current 230 µA
V
OUT
Output Voltage Swing ±14.4 V
I
SC
Output Short-Circuit Current Short to V
5mA
Short to V
+
13 mA
SR Slew Rate G = 1, V
OUT
= ±10V 0.25 V/µs
±15V ELECTRICAL CHARACTERISTICS
The denotes the specifications which apply over the temperature range of 0°C TA 70°C. VS = ±15V, RL = 10k, VCM = VREF = 0V,
G = 1, 10, unless otherwise noted. (Notes 4, 6)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
I
SC
Output Short-Circuit Current Short to V
69 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/µs
Settling Time to 0.01% 10V Step, G = 1 60 µs
AV
REF
Reference Gain to Output G = 1 1 ± 0.0007
G = 10 1 ± 0.007
VS = ±15V, RL = 10k, VCM = VREF = 0V, G = 1, 10, TA = 25°C, unless otherwise noted. (Note 6)
LT1990
8
1990fb
LT1990C/LT1990I
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
G Gain Error V
OUT
= ±10V
LT1990, G = 1 0.67 %
LT1990A, G = 1 0.35 %
G = 10 0.95 %
GNL Gain Nonlinearity V
OUT
= ±10V
G = 1 0.003 %
G = 10 0.03 %
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 250 250 V
CMRR Common Mode Rejection Ratio, RTI V
CM
= –250V to 250V
LT1990 58 dB
LT1990A 67 dB
V
OS
Input Offset Voltage, RTI G = 1, 10 6.7 mV
V
OS
/T Input Offset Voltage Drift, RTI (Note 10) 522µV/°C
V
OSH
Input Offset Voltage Hysteresis, RTI (Note 11) 250 µV
PSRR Power Supply Rejection Ratio, RTI V
S
= ±1.35V to ±18V 78 dB
Minimum Supply Voltage Guaranteed by PSRR ±1.35 V
I
S
Supply Current 280 µA
V
OUT
Output Voltage Swing ±14.3 V
I
SC
Output Short-Circuit Current Short to V
3mA
Short to V
+
10 mA
SR Slew Rate G = 1, V
OUT
= ±10V 0.2 V/µs
±15V ELECTRICAL CHARACTERISTICS
The denotes the specifications which apply over the temperature range of –40°C TA 85°C. VS = ±15V, RL = 10k, VCM = VREF = 0V,
G = 1, 10, unless otherwise noted. (Notes 4, 6)
LT1990H
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
G Gain Error V
OUT
= ±10V
LT1990, G = 1 0.69 %
LT1990A, G = 1 0.37 %
G = 10 0.97 %
GNL Gain Nonlinearity V
OUT
= ±10V
G = 1 0.0035 %
G = 10 0.035 %
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 250 250 V
CMRR Common Mode Rejection Ratio, RTI V
CM
= –250V to 250V
LT1990 57 dB
LT1990A 66 dB
V
OS
Input Offset Voltage, RTI G = 1, 10 7.4 mV
V
OS
/T Input Offset Voltage Drift, RTI (Note 10) 522µV/°C
±15V ELECTRICAL CHARACTERISTICS
The denotes the specifications which apply over the temperature range of –40°C TA 125°C. VS = ±15V, RL = 10k, VCM = VREF = 0V,
G = 1, 10, unless otherwise noted. (Notes 4, 6)
LT1990
9
1990fb
LT1990H
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
OSH
Input Offset Voltage Hysteresis, RTI (Note 11) 250 µV
PSRR Power Supply Rejection Ratio, RTI V
S
= ±1.35V to ±18V 77 dB
Minimum Supply Voltage Guaranteed by PSRR ±1.35 V
I
S
Supply Current 330 µA
V
OUT
Output Voltage Swing ±14.2 V
I
SC
Output Short-Circuit Current Short to V
1.5 mA
Short to V
+
7mA
SR Slew Rate G = 1, V
OUT
= ±10V 0.1 V/µs
±15V ELECTRICAL CHARACTERISTICS
The denotes the specifications which apply over the temperature range of –40°C TA 125°C. VS = ±15V, RL = 10k, VCM = VREF = 0V,
G = 1, 10, unless otherwise noted. (Notes 4, 6)
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, 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 LT1990C/LT1990I are guaranteed functional over the
operating temperature range of –40°C to 85°C. The LT1990H is
guaranteed functional over the operating temperature range of –40°C
to 125°C.
Note 5: The LT1990C is guaranteed to meet the specified performance
from 0°C to70°C and is designed, characterized and expected to meet
specified performance from –40°C to 85°C but is not tested or QA
sampled at these temperatures. The LT1990I is guaranteed to meet
specified performance from –40°C to 85°C. The LT1990H is guaranteed to
meet specified performance from –40°C to 125°C.
Note 6: G = 10 limits are guaranteed by correlation to G = 1 tests and gain
error tests at G = 10.
Note 7: Limits are guaranteed by correlation to –5V to 80V CMRR tests.
Note 8: V
S
= 3V limits are guaranteed by correlation to V
S
= 5V and
V
S
= ±15V tests.
Note 9: V
S
= 5V limits are guaranteed by correlation to V
S
= 3V and
V
S
= ±15V tests.
Note 10: This parameter is not 100% tested.
Note 11: 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 I-grade (70°C C-grade or 125°C H-grade) or –40°C
I/H-grade (0°C C-grade) before successive measurement.
LT1990
10
1990fb
Supply Current
vs Supply Voltage
Supply Current
vs Temperature
Output Voltage Swing
vs Load Current
Output Voltage vs
Input Voltage, G = 1
Output Short-Circuit Current
vs Supply Voltage
Input Voltage Range vs Single
Supply Voltage
Input Voltage Range vs Split
Supply Voltage
TYPICAL PERFOR A CE CHARACTERISTICS
UW
Output Voltage vs
Input Voltage, G = 10
Output Voltage Swing vs
Supply Voltage
G = 1, V
+IN
= V
SUPPLY CURRENT (µA)
220
200
180
160
140
120
100
80
60
40
1990 G01
SUPPLY VOLTAGE (V)
040
10 20 30
51525
35
T
A
= 125°C
T
A
= 85°C
T
A
= –40°C
T
A
= –55°C
T
A
= 25°C
V
REF
= V
OUT
= 1.25V
V
= 0V
TEMPERATURE (°C)
–50 –25
SUPPLY CURRENT (µA)
10075
150
140
130
120
110
100
90
80
70
60
1990 G02
0 25 50 125
V
S
= 5V, 0V
OUTPUT CURRENT (mA)
0.001 0.01 0.1 1 10 100
OUTPUT VOLTAGE SWING
WITH RESPECT TO SUPPLY (V)
1990 G03
SUPPLY VOLTAGE (±V)DIFFERENTIAL INPUT VOLTAGE (±V)
DIFFERENTIAL INPUT VOLTAGE (±V)
01.00.80.60.40.20
4.03.53.02.52.01.51.00.50 2 4 6 8 10 12 14 16
1990 G061990 G05
1990 G04
0.01
0.1
–1
+1
+0.1
+0.01
SOURCING
(+IN = 2.5V)
SINKING
(+IN = –2.5V)
V
S
= ±2.5V
–IN = 0V
G = 1
T
A
= 125°C
T
A
= 125°C
T
A
= –55°C
T
A
= –55°C
T
A
= 25°C
T
A
= 25°C
SUPPLY VOLTAGE (±V)
1
MAXIMUM INPUT VOLTAGE (V)
300
200
100
0
100
200
300 711
1990 G09
35 91315
V
REF
= 0V
T
A
= –40°C TO 85°C
0.01
0.1
+0.1
+0.01
OUTPUT SWING WITH
RESPECT TO SUPPLY (V)
0.01
0.1
–1
+1
+0.1
+0.01
OUTPUT VOLTAGE WITH
RESPECT TO SUPPLY (V)
0.01
0.1
–1
+0.1
+1
+0.01
OUTPUT VOLTAGE WITH
RESPECT TO SUPPLY (V)
OUTPUT FULLY
SATURATED
G = 10 G = 1
G = 10, V
+IN
= V
+
/10
G = 10, V
+IN
= V
/10
G = 1, V
+IN
= V
+
G = 10 G = 1
OUTPUT FULLY
SATURATED
V
–IN
= 0V
V
REF
= 0V
NO LOAD
T
A
= 25°C
V
S
= ±2.5V
G = 1
NO LOAD
V
S
= ±2.5V
G = 10
NO LOAD
T
A
= –55°C
T
A
= –55°C
T
A
= 125°C
T
A
= 125°C
T
A
= 25°C
T
A
= –55°C
T
A
= 125°C
T
A
= 25°C
T
A
= –55°C
T
A
= 125°C
T
A
= 25°C
T
A
= 25°C
POSITIVE SUPPLY VOLTAGE (V)
MAXIMUM INPUT VOLTAGE (V)
250
200
150
100
50
0
–50
100
1990 G08
1990 G07
357 9 11 13 15
V
= 0V
T
A
= –40°C TO 85°C
V
REF
= 1.25V
V
REF
= 1.25V
V
REF
= 4V
V
REF
= 4V
V
REF
= 2.5V
V
REF
= 2.5V
SUPPLY VOLTAGE (±V)
0
OUTPUT SHORT-CIRCUIT CURRENT (mA)
25
20
15
10
5
0
–5
–10
–15
–20
–25
–30 1412
42 6108 16
SOURCE
SINK
T
A
= –55°C
T
A
= –55°C
T
A
= 125°C
T
A
= 125°C
T
A
= 25°C
T
A
= 25°C
V
V
+
V
V
+
V
V
+
V
V
+
LT1990
11
1990fb
TYPICAL PERFOR A CE CHARACTERISTICS
UW
Gain vs Frequency
3dB Bandwidth vs Supply
Voltage, G = 1
3dB Bandwidth vs Supply
Voltage, G = 10
Slew Rate vs Supply Voltage,
G = 1
Slew Rate vs Supply Voltage,
G = 10
Slew Rate vs Temperature
G = 1
Slew Rate vs Temperature
G = 10
Common Mode Rejection Ratio
vs Frequency
FREQUENCY (Hz)
GAIN (dB)
50
40
30
20
10
0
–10
–20
–30
–40
–50
100 10k1k 100k 1M
1990 G12
FREQUENCY (kHz)
1990 G13
120
115
110
105
100
95
90
85
80
75
70
SUPPLY VOLTAGE (±V)
0
FREQUENCY (kHz)
16
1990 G14
4812 14
2610
SUPPLY VOLTAGE (±V)
016
4812 14
2610
8
7
6
5
4
3
SLEW RATE (V/µs)
1.0
0.8
0.6
0.4
0.2
0
1990 G17
SLEW RATE (V/µs)
0.6
0.5
0.4
0.3
0.2
0.1
0
1990 G18
V
S
= 5V, 0V
T
A
= 25°C
T
A
= 25°C
T
A
= 125°C
T
A
= –55°C
T
A
= 25°C
T
A
= 125°C
T
A
= –55°C
G = 1
G = 10
T
A
= 25°C
T
A
= 25°C
TEMPERATURE (°C)
–50 25 75
–25 0 50 100 125
TEMPERATURE (°C)
–50 25 75
–25 0 50 100 125
V
S
= ±15V
R
L
= 10k
V
S
= ±15V
R
L
= 10k
–SR
+SR
–SR
+SR
FREQUENCY (Hz)
100
COMMON MODE REJECTION RATIO (dB)
100
90
80
70
60
50
40
30
20
10
01k 10k 200k
100k
1990 G10
V
S
= 5V, 0V
T
A
= 25°C
G = 1 OR 10
REFERRED TO INPUT
+SR
–SR
SUPPLY VOLTAGE (±V)
0
SLEW RATE (V/µs)
1.0
0.8
0.6
0.4
0.2
0610 16
1990 G15
24 812 14
T
A
= 25°C
R
L
= 10k
+SR
–SR
SUPPLY VOLTAGE (±V)
0
SLEW RATE (V/µs)
0.5
0.4
0.3
0.2
0.1
0610 16
1990 G16
24 812 14
T
A
= 25°C
R
L
= 10k
LT1990
12
1990fb
TYPICAL PERFOR A CE CHARACTERISTICS
UW
Warm-Up Drift vs Time
Settling Time vs Output Step,
G = 1
Settling Time vs Output Step,
G = 10
Voltage Noise Density
vs Frequency
0.01 to 1Hz Noise Voltage
0.1 to 10Hz Noise Voltage Overshoot vs Capacitive Load
Output Impedance vs Frequency
Power Supply Rejection Ratio
vs Frequency
OUTPUT STEP (V)
–10
SETTLING TIME (µs)
60
50
40
30
20 6
1990 G22
–6–8 –4 –2 0 4 8210
OUTPUT STEP (V)
–10 6
–6–8 –4 –2 0 4 8210
SETTLING TIME (µs)
320
300
280
260
240
220
200
180
160
140
1990 G23
TIME (S)
080
1990 G26
2010 30 50 70 90
40 60 100
TIME (S)
0
NOISE VOLTAGE (10µV/DIV)
REF
NOISE VOLTAGE (10µV/DIV)
REF
8
1990 G25
213579
4610
FREQUENCY (Hz)
10
100
1000
10000
100 1000
1990 G24
VOLTAGE NOISE DENSITY (nV/Hz)
110000
CAPACITIVE LOAD (pF)
10
OVERSHOOT (%)
30
25
20
15
10
5100 1000 10000
1990 G27
0.01% OF
STEP
0.01% OF
STEP
0.1% OF
STEP
0.1% OF
STEP
0.01% OF
STEP
0.01% OF
STEP
0.1% OF
STEP 0.1% OF
STEP
V
S
= ±15V
R
L
= 10k
V
S
= ±15V
R
L
= 10k
V
OUT
= ±50mV
GAIN = 1
R
L
= 10k
V
S
= ±1.5V TO ±15V
T
A
= 25°C
V
S
= ±1.5V TO ±15V
T
A
= 25°C
G = 1
V
S
= ±1.5V TO ±15V
T
A
= 25°C
G = 1
V
S
= ±15V
V
S
= 3V, 0V
FREQUENCY (Hz)
10
OUTPUT IMPEDANCE ()
100
1k
5k
100 10k 100k
1990 G19
1
1k 200k
FREQUENCY (Hz)
POWER SUPPLY REJECTION RATIO (dB)
70
60
50
40
30
20
10
0
–10
–20
–30
–40
10 1k 10k
1990 G20
100 100k 200k
V
S
= 5V, 0V
T
A
= 25°C
G = 1
G = 10
G = 1
G = 10
TIME AFTER POWER-UP (S)
0
CHANGE IN OFFSET VOLTAGE (µV)
60
40
20
0
–20
–40
–60 10 20 30 40
1990 G21
50
V
S
= ±15V
T
A
= 25°C
REFERRED TO INPUT
V
S
= 5V, 0V
T
A
= 25°C
LT1990
13
1990fb
Large Signal Transient Response
Small Signal Transient Response Small Signal Transient Response
TYPICAL PERFOR A CE CHARACTERISTICS
UW
5V/DIV
VS = ±15V
G = 1, –1
RL = 10k
VREF = GND
50µs/DIV
GND
1990 G30
50mV/DIV
50mV/DIV
VS = ±15V
G = 1, –1
RL = 10k
VREF = GND
VS = 3V, 0V
G = 1, –1
RL = 10k
VREF = 1.5V
50µs/DIV 50µs/DIV
GND
1.5V
1990 G28 1990 G29
+
6
8
5
7
2
3
4
1
V
+
–IN
V
+IN
REF
GAIN1
OUT
GAIN2
R5
900k
R7
10k
R10
10k
R1
1M
R2
1M
R6
100k
R9
100k
R4
40k
R3
40k
R8
900k
1990 SS
BLOCK DIAGRA
W
REF (Pin 1): Reference Input. Sets the output level when
the difference between the inputs is zero.
–IN (Pin 2): Inverting Input. Connects a 1M resistor to
the op amp’s inverting input. Designed to permit high
voltage operation.
+IN (Pin 3): Noninverting Input. Connects a 1M resistor
to the op amp’s noninverting input. Designed to permit
high voltage operation.
V
(Pin 4): Negative Power Supply. Can be either ground
(in single supply applications) or a negative voltage (in
split supply applications).
GAIN2 (Pin 5): Gain = 10 Select Input. Configures the
amplifier for a gain of 10 when connected to the GAIN1 pin
and the REF pin. The gain is equal to one when both GAIN2
and GAIN1 are open. See Applications section for addi-
tional functions.
OUT (Pin 6): Output. V
OUT
= G • (V
+IN
– V
–IN
) + V
REF
, in the
basic configuration.
V
+
(Pin 7): Positive Power Supply. Can range from 2.7V to
36V above the V
voltage.
GAIN1 (Pin 8): Gain = 10 Select Input. Configures the
amplifier for a gain of 10 when connected to the GAIN2 pin
and the REF pin. The gain is equal to one when both GAIN1
and GAIN2 are open. See Applications section for addi-
tional functions.
UU
U
PI FU CTIO S
LT1990
14
1990fb
V
CM+
27 • V
+
– 26 • V
REF
– 23 – V
GAIN
V
CM–
27 • V
– 26 • V
REF
+ 27 – V
GAIN
For split supplies over about ±11V, the full ±250V common
mode range is normally available (with V
REF
a small
fraction of the supply). With lower supply voltages, an
appropriate selection of V
REF
can tailor the input common
mode range to a specific requirement. As an example, the
following low supply voltage scenarios are readily imple-
mented with the LT1990:
Supply V
REF
V
CM
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)
Configuring Other Gains
An intermediate gain G ranging between 1 and 10 may be
produced by placing an adjustable resistance between the
GAIN1 and GAIN2 pins according to the following nominal
relationship:
R
GAIN
(180k/(G – 1)) – 20k
While the expression is exact, the value is approximate
because the absolute resistance of the internal network
could vary on a unit-to-unit basis by as much as ±30%
from the nominal figures and the external gain resistance
is required to accommodate that deviation. Once ad-
justed, however, the gain stability is excellent by virtue of
the –30ppm/°C typical temperature coefficient offered by
the on-chip thin-film resistor process.
Preserving and Enhancing Common Mode Rejection
The basic difference amplifier topology of the LT1990
requires that source impedances seen by the input pins
+IN and –IN, should be matched to within a few tens of
ohms to avoid increasing common mode induced errors
beyond the basic production limits of the part. Known
source imbalances beyond that level should be compen-
sated for by the addition of series resistance to the lower-
impedance source. Also the source impedance of a signal
connected to the REF pin must be on the order of a few
ohms or less to preserve the high accuracy of the LT1990.
APPLICATIO S I FOR ATIO
WUUU
Primary Features
The LT1990 is a complete gain-block solution for high
input common mode voltage applications, incorporating a
low power precision operational amplifier providing rail-
to-rail output swing along with on-chip precision thin-film
resistors for 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.
With pin-strapping alone either unity gain or gain of 10 is
produced with high precision. The resistor network is
designed to produce internal common-mode voltage divi-
sion of 27 so that a very large input range is available
compared to the power supply voltage(s) used by the
LT1990 itself. The LT1990 is ideally suited to situations
where relatively small signals need to be extracted from
high voltage circuits, as is the case in many current
monitoring instrumentation applications for example. With
the ability to accept a range of input voltages well outside
the limits of the local power rails and its greater than 1M
input impedances, development of precision low power
over-the-top and under-the-bottom instrumentation de-
signs is greatly simplified with the LT1990 single chip
solution over conventional discrete implementations.
Classic Difference Amplifier
Used in the basic difference amplifier topology where the
gain G is pin-strap configurable to be unity or ten, the
following relationship is realized:
V
O
= G • (V
+IN
– V
–IN
) + V
REF
To operate in unity gain, the GAIN1 and GAIN2 pins are left
disconnected. For G = 10 operation, the GAIN1 and GAIN2
pins are simply connected to the REF pin.
The input common mode range capability is up to ±250V,
governed by the following relationships:
For G = 1 and G = 10 where GAIN1 and GAIN2 are only tied
together (not grounded,etc):
V
CM+
27 • V
+
– 26 • V
REF
– 23
V
CM–
27 • V
– 26 • V
REF
+ 27
For G = 10 where GAIN1 and GAIN2 are tied to a common
potential V
GAIN
:
LT1990
15
1990fb
APPLICATIO S I FOR ATIO
WUUU
While the LT1990 comes from the factory with an excellent
CMRR, some precision applications with a large applied
common mode voltage may require a method to trim out
residual common mode error. This is easily accomplished
by adding series resistance to each input, +IN and –IN,
such that an adjustable resistance difference of ±1k is
provided. This is most easily realized by adding a fixed
1k in series with one of the inputs, and a 2k trimmer in
series with the other as shown in Figure 1. The trim range
of this configuration is ±0.1% for the internal gain resistor
matching, so a much more finely resolved correction is
available using the LT1990 than is realizable with ordinary
discrete solutions. In applications where the input
common mode voltage is relatively constant and large
(perhaps at or beyond the supply range), this same
configuration can be treated as an offset adjustment.
+
LT1990
1k
2k
Figure 1. Optional CMRR Trim
Dual Differential-Input Arithmetic Block
The internal resistor network topology of the LT1990
allows the GAIN1 and GAIN2 pins to be used as another
differential input in addition to the normal +IN and –IN
port. This can be a very useful function for implementing
servo-loop differential error amplifiers, for example. In
this mode of operation, the output is governed by the
following relationship:
V
O
= 10 • (V
+IN
– V
–IN
+ V
GAIN2
– V
GAIN1
) + V
REF
Unlike the main inputs, the GAIN1 and GAIN2 pins are
clamped by substrate diodes and ESD structures, thus the
operating voltage range of these pins is limited to V
– 0.2V
to V
+ 36V. If the GAIN inputs are brought beyond the
operating input range, care must be taken to limit the input
currents to less than 10mA to prevent damage to the device.
For best results in this mode of operation the common mode
voltage of the GAIN1 and GAIN2 pins should be equal to the
REF pin voltage. Also, since the gain setting resistors associ-
ated with the GAIN1 and GAIN2 inputs are in the 10k area,
low source impedances are particularly important to preserve
the precision of the LT1990.
This dual differential input mode of operation is used in the
circuit as shown in Figure 2.
This circuit is a high efficiency H-bridge driver that is PWM
modulated to provide a controlled current to an electro-
magnet coil. Since the common mode voltage of the
current sense resistor R
S
varies with operating current
and the coil properties, a differential feedback is required.
In this application, it was desirable to allow the control
input to utilize the wide common mode range port (+IN and
–IN) so that constraints on input referencing are elimi-
nated. The GAIN1 and GAIN2 pins always operate within
the supply range and both ports operate with a gain of 10
to develop the loop error. The LTC1923 provides the loop
integrator and PWM functions of the servo.
Figure 2. PWM-Based ±1A Electromagnet Current Controller
PLLLPF
R
SLEW
SDSYNC
CNTRL
EAOUT
FB
AGND
SS
I
LIM
R
T
C
T
V
REF
PDRVB
NDRVB
V
DD
PGND
NDRVA
PDRVA
LTC1923
V
DD
+
LT1990
REF
10k
10k
330pF
1µF
10µF
L1
10µH
V
DD
R
S
0.1
C1, C2, C3: TAIYO YUDEN JMK325BJ226MM-T (X7R)
L1, L2: SUMIDA CDRH6D2B-220NC
*MNA, MPA: SILICONIX Si9801
**MNB, MPB: SILICONIX Si9801
1990 F02
10nF
10nF
1µF
100k
100k
20k
100k
10k
1µF
L2
10µH
C1
22µF
C2
22µF
C3
22µF
MPA*
V
REF
MPB**
MNA*
MNB**
100k
82k
G2
G1
1
4
8
6
5
7
3
2
V
IN
+
V
IN
V
DD
I
COIL
ELECTRO-
MAGNET
COIL
0.1
I
COIL
= (V
IN
+ – V
IN
)/(10 • R
S
)
(i.e. ±1A FOR ±1V)
V
THRM
H/C
V
TEC
I
TEC
TEC
+
TEC
V
SET
FAULT
CS
+
CS
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-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
LT1990
16
1990fb
© LINEAR TECHNOLOGY CORPORATION 2004
LT 0406 REV B • PRINTED IN USA
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+
LT6650
GND
IN OUT
FB
174k
20k
1nF
1µF
VREF = 4V
1
2
3
2
6
5
7
4
1
8
45
LOAD
RS
48V
IL
+
5V
VOUT
1990 AI01
–77V V
CM
8V
V
OUT
= V
REF
– (10 • I
L
• R
S
)
LT1990
REF
G1
G2
+
3
2
6
7
4
8
5
1
+V
–V
LT1990 V
OUT
V
IN
+
V
IN
1990 AI02
REF
2N7002
2N7002
GAIN_SEL
(HI = 10X, LO = 1X)
G1
G2
+
3
2
6
7
4
1
+V
–V
LT1990
I
LOAD
I
LOAD =
V
CTL
/R
SENSE
5mA
EXAMPLE: FOR R
SENSE
=100,
OUTPUT IS 1mA PER 100mV INPUT
V
CTL
R
SENSE
1990 AI03
REF
+
3
2
6
7
4
1
+V
–V
LT1990
I
LOAD
I
LOAD =
V
CTL
/R
SENSE
100mA
EXAMPLE: FOR R
SENSE
=10,
OUTPUT IS 1mA PER 10mV INPUT
V
CTL
R
SENSE
1990 AI04
10µF
1k
1k
REF
CZT751
CZT651
+
PACKAGE DESCRIPTIO
U
.016 – .050
(0.406 – 1.270)
.010 – .020
(0.254 – 0.508)× 45°
0°– 8° TYP
.008 – .010
(0.203 – 0.254)
SO8 0303
.053 – .069
(1.346 – 1.752)
.014 – .019
(0.355 – 0.483)
TYP
.004 – .010
(0.101 – 0.254)
.050
(1.270)
BSC
1234
.150 – .157
(3.810 – 3.988)
NOTE 3
8765
.189 – .197
(4.801 – 5.004)
NOTE 3
.228 – .244
(5.791 – 6.197)
.245
MIN .160 ±.005
RECOMMENDED SOLDER PAD LAYOUT
.045 ±.005
.050 BSC
.030 ±.005
TYP
INCHES
(MILLIMETERS)
NOTE:
1. DIMENSIONS IN
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)
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)