OP490

Rev. E | Page 9 of 16

APPLICATIONS INFORMATION

GND

+18V

12

3

4

5

6

7

14

13

12

11

10

9

8

–18V

AB

DC

Figure 19. Burn-In Circuit

+15V

1/4

OP490

A

+

–

OP37

A

+

–

+15V

V2

V1

20V p-p @ 10Hz

1k

Ω

100

Ω

10k

Ω

1/4

OP490

B

+

–

1/4

OP490

C

+

–

1/4

OP490

D

+

–

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.

4

3

0

1

2

HOURS

0

250

500

1000

1250

1500

750

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.