LT1490 Datasheet, PDF (1/12 Pages) Linear Technology – Dual and Quad Micropower Rail-to-Rail Input and Output Op Amps

LT1490/LT1491
Dual and Quad
Micropower Rail-to-Rail
Input and Output Op Amps
FEATURES
s _{Rail-to-Rail Input and Output}
s _{Single Supply Input Range: – 0.4V to 44V}
s _{Micropower: 50µA/Amplifier Max}
s _{Specified on 3V, 5V and ±15V Supplies}
s _{High Output Current: 20mA}
s _{Output Drives 10,000pF with Output Compensation}
s _{Reverse Battery Protection to 18V}
s _{No Supply Sequencing Problems}
s _{High Voltage Gain: 1500V/mV}
s _{High CMRR: 98dB}
s _{No Phase Reversal}
s _{Gain Bandwidth Product: 200kHz}
U
APPLICATIONS
s _{Battery- or Solar-Powered Systems}
Portable Instrumentation
Sensor Conditioning
s _{Supply Current Sensing}
s _{Battery Monitoring}
s _{Micropower Active Filters}
s _{4mA to 20mA Transmitters}
DESCRIPTION
The dual LT^®1490 and quad LT1491 op amps 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 no current
for reverse supply up to 18V. The input range of the LT1490/
LT1491 includes both supplies and the output swings to both
supplies. Unlike most micropower op amps, the LT1490/
LT1491 can drive heavy loads; their rail-to-rail outputs drive
20mA. The LT1490/LT1491 are unity-gain stable and drive all
capacitive loads up to 10,000pF when optional 0.22µF and
150Ω compensation is used.
The LT1490/LT1491 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 resis-
tors protect the inputs for faults below the negative supply
up to 22V. There is no phase reversal of the output for inputs
22V below V ^– or 44V above V^–, independent of V ⁺.
The LT1490 dual op amp is available in the 8-pin SO and
PDIP packages. The quad LT1491 is available in the 14-pin
SO and PDIP packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATION
CHARGER
VOLTAGE
R_S
RA
0.2Ω
2k
I_BATT
R_A'
2k
Battery Monitor
+
A
1/4 LT1491
–
Q1
2N3904
LOAD
R_B
2k
R_B'
2k
+
V_BATT = 12V
+
B
1/4 LT1491
–
Q2
2N3904
S1
R_G
10k
10k
–
C
1/4 LT1491
+
LOGIC
LOGIC HIGH (5V) = CHARGING
LOGIC LOW (0V) = DISCHARGING
+
D
1/4 LT1491
V_OUT
–
90.9k
I_BATT
=
V_OUT
=
(R_S)(R_G/R_A)(GAIN)
V_{OUT AMPS}
GAIN
S1 = OPEN, GAIN = 1
S1 = CLOSED, GAIN = 10
R_A = R_B
V_S = 5V, 0V
1490/91 TA01
1