LT1490A
Dual Over-The-Top
Micropower Rail-to-Rail
Input and Output Op Amp
FEATURES
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DESCRIPTIO
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Low Input Offset Voltage: 500
µ
V Max
Output Swings to 10mV Max from V
–
Rail-to-Rail Input and Output
Micropower: 50µA/Amplifier Max
µ
MSOP Package
Over-The-Top
TM
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
APPLICATIO S
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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 LT
®
1490A is an enhanced version of the popular LT1490
op amp with improved input offset voltage (500µV max) and
output voltage swing (10mV max from V
–
). It is recom-
mended for all new designs. The LT1490A operates on all
single and split supplies with a total voltage of 2V to 44V,
drawing only 40µA of quiescent current per amplifier. It is
reverse supply protected; it draws virtually no current for
reverse supply up to 18V. The input range of the LT1490A
includes both supplies and the output swings to both sup-
plies. Unlike most micropower op amps, the LT1490A can
drive heavy loads; its rail-to-rail output drives 20mA. The
LT1490A is unity-gain stable and drives all capacitive loads
up to 10,000pF when optional 0.22µF and 150Ω compensa-
tion is used.
The LT1490A has 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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Over-The-Top is a trademark of Linear Technology Corporation.
TYPICAL APPLICATIO
CHARGER
VOLTAGE
Battery Monitor
R
S
0.2Ω
I
BATT
RA
2k
R
A
´
2k
+
1/2 LT1490A
Q1
2N3904
–
1/2 LT1490A
LOGIC
–
Q2
2N3904
+
R
B
2k
R
B
´
2k
LOAD
+
1/2 LT1490A
LOGIC HIGH (5V) = CHARGING
LOGIC LOW (0V) = DISCHARGING
–
R
G
10k
S1
10k
+
1/2 LT1490A
V
OUT
+
V
BATT
= 12V
–
90.9k
14901A TA01
V
OUT
V
I
BATT
=
=
OUT
AMPS
(R
S
)(R
G
/R
A
)(GAIN) GAIN
S1 = OPEN, GAIN = 1
S1 = CLOSED, GAIN = 10
R
A
= R
B
V
S
= 5V, 0V
U
U
U
1
LINER [ LINEAR TECHNOLOGY ]
