OP490
Rev. E | Page 9 of 16
APPLICATIONS INFORMATION
00308-019
GND
+18
12345 67
14 13 12 11 10 9 8
18
AB
DC
Figure 19. Burn-In Circuit
V
IN
+15
–15V
00308-020
1/4
OP490
A
+
–
OP37
A
+
–
+15V
V2
V1
20V p-p @ 10Hz
1k
100 10k
1/4
OP490
B
+
–
1/4
OP490
C
+
–
1/4
OP490
D
+
–
–15V
CHANNEL SEPARATION = 20 log
V1
V2/1000
Figure 20. Channel Separation Test Circuit
BATTERY-POWERED APPLICATIONS
The OP490 can be operated on a minimum supply voltage of
1.6 V or with dual supplies of ±0.8 V drawing only 60 μA of
supply current. In many battery-powered circuits, the OP490
can be continuously operated for hundreds of hours before
requiring battery replacement, thereby reducing equipment
downtime and operating costs.
High performance portable equipment and instruments
frequently use lithium cells because of their long shelf life, light
weight, and high energy density relative to older primary cells.
Most lithium cells have a nominal output voltage of 3 V and are
noted for a flat discharge characteristic. The low supply current
requirement of the OP490, combined with the flat discharge
characteristic of the lithium cell, indicates that the OP490 can
be operated over the entire useful life of the cell. Figure 21
shows the typical discharge characteristic of a 1 Ah lithium cell
powering an OP490 with each amplifier, in turn, driving full
output swing into a 100 kΩ load.
00308-021
4
3
0
1
2
LITHIUM-SULPHUR DIOXIDE CELL VOLTAGE (V)
HOURS
0 250 500 1000 1250 1500750
Figure 21. Lithium-Sulphur Dioxide Cell Discharge Characteristic with
OP490 and 100 kΩ Loads
SINGLE-SUPPLY OUTPUT VOLTAGE RANGE
In single-supply operation the input and output ranges of the
OP490 include ground. This allows true zero-in, zero-out
operation. The output stage provides an active pull-down to
around 0.8 V above ground. Below this level, a load resistance of up
to 1 MΩ to ground is required to pull the output down to zero.
In the region from ground to 0.8 V, the OP490 has voltage gain
equal to the data sheet specification. Output current source
capability is maintained over the entire voltage range including
ground.
