LT1490A/LT1491A
Dual/Quad Over-The-Top
Micropower Rail-to-Rail
Input and Output Op Amps
DESCRIPTION
FEATURES
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Low Input Offset Voltage: 500μV Max
Output Swings to 10mV Max from V–
Rail-to-Rail Input and Output
Micropower: 50μA/Amplifier Max
Over-The-Top® Input Common Mode Range Extends
44V Above V–, Independent of V+
Specified on 3V, 5V and ±15V Supplies
High Output Current: 20mA
Output Drives 10,000pF with Output Compensation
Reverse Battery Protection to 18V
No Supply Sequencing Problems
High Voltage Gain: 1500V/mV
High CMRR: 98dB
No Phase Reversal
Gain Bandwidth Product: 200kHz
Tiny 3mm × 3mm × 0.8mm DFN Package
APPLICATIONS
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Battery- or Solar-Powered Systems
Portable Instrumentation
Sensor Conditioning
Supply Current Sensing
Battery Monitoring
Micropower Active Filters
4mA to 20mA Transmitters
The LT1490A/LT1491A have a unique input stage that operates and remains high impedance when above the positive
supply. The inputs take 44V both differential and common
mode even when operating on a 3V supply. Built-in resistors
protect the inputs for faults below the negative supply up to
15V. There is no phase reversal of the output for inputs 15V
below V– or 44V above V–, independent of V+.
The LT1490A dual op amp is available in the 8-pin MSOP PDIP
,
and SO packages. For space limited applications LT1490A is
available in a 3mm × 3mm × 0.8mm, dual fine pitch leadless
package (DFN). The quad LT1491A is available in the 14-pin
SO, PDIP and 5mm × 3mm × 0.8mm DFN packages.
L, LT, LTC, LTM, Over-The-Top, Linear Technology and the Linear logo are registered
trademarks of Linear Technology Corporation. All other trademarks are the property of their
respective owners. Protected by U.S. Patents including 5825228.
TYPICAL APPLICATION
Battery Monitor
RS
0.2Ω
RA
2k
IBATT
CHARGER
VOLTAGE
The LT®1490A/LT1491A are dual and quad op amps with a
low input offset voltage of 500μV max. The LT1490A/LT1491A
operate on all single and split supplies with a total voltage of
2V to 44V, drawing only 40μA of quiescent current per amplifier. These amplifiers are reverse supply protected; they draw
virtually no current for reverse supply up to 18V. The input
range of the LT1490A/LT1491A includes both supplies and
the output swings to both supplies. Unlike most micropower
op amps, the LT1490A/LT1491A can drive heavy loads; their
rail-to-rail outputs drive 20mA. The LT1490A/LT1491A are
unity-gain stable and drive all capacitive loads up to 10,000pF
when optional 0.22μF and 150Ω compensation is used.
RA´
2k
+
Q1
2N3904
1/4 LT1491A
–
–
1/4 LT1491A
LOGIC
+
RB
2k
R B´
2k
LOAD
+
Q2
2N3904
LOGIC HIGH (5V) = CHARGING
LOGIC LOW (0V) = DISCHARGING
1/4 LT1491A
–
+
+
RG
10k
VBATT = 12V
S1
1/4 LT1491A
VOUT
–
10k
90.9k
S1 = OPEN, GAIN = 1
S1 = CLOSED, GAIN = 10
RA = RB
VS = 5V, 0V
1490A TA01
IBATT =
VOUT
V
= OUT AMPS
(RS)(RG /RA)(GAIN) GAIN
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