LT1490A/LT1491A
1
14901afd
TYPICAL APPLICATION
FEATURES DESCRIPTION
Dual/Quad Over-The-Top
Micropower Rail-to-Rail
Input and Output Op Amps
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 ampli-
fier. 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 150 compensation is used.
The LT1490A/LT1491A have a unique input stage that oper-
ates 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.
Battery Monitor
APPLICATIONS
n
Low Input Offset Voltage: 500μV Max
n
Output Swings to 10mV Max from V
–
n
Rail-to-Rail Input and Output
n
Micropower: 50μA/Amplifier Max
n
Over-The-Top
®
Input Common Mode Range Extends
44V Above V
–
, Independent of V
+
n
Specified on 3V, 5V and ±15V Supplies
n
High Output Current: 20mA
n
Output Drives 10,000pF with Output Compensation
n
Reverse Battery Protection to 18V
n
No Supply Sequencing Problems
n
High Voltage Gain: 1500V/mV
n
High CMRR: 98dB
n
No Phase Reversal
n
Gain Bandwidth Product: 200kHz
n
Tiny 3mm × 3mm × 0.8mm DFN Package
n
Battery- or Solar-Powered Systems
Portable Instrumentation
Sensor Conditioning
n
Supply Current Sensing
n
Battery Monitoring
n
Micropower Active Filters
n
4mA to 20mA Transmitters
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.
–
+
–
+
R
A
2k
Q2
2N3904
S1
S1 = OPEN, GAIN = 1
S1 = CLOSED, GAIN = 10
R
A
= R
B
V
S
= 5V, 0V
10k
90.9k
V
OUT
LOGIC
1490A TA01
LOGIC HIGH (5V) = CHARGING
LOGIC LOW (0V) = DISCHARGING
R
G
10k
Q1
2N3904
R
S
0.2
CHARGER
VOLTAGE
1/4 LT1491A
1/4 LT1491A
R
A´
2k
R
B
2k
V
BATT
= 12V
I
BATT
+
R
B´
2k
LOAD
–
+
–
+
V
OUT
(R
S
)(R
G
/R
A
)(GAIN)
V
OUT
GAIN
I
BATT
= = AMPS
1/4 LT1491A
1/4 LT1491A
