Data Sheet

ADA4096-2

Rev. A | Page 17 of 20

COMPARATOR OPERATION

Although op amps are quite different from comparators,

occasionally an unused section of a dual or a quad op amp

may be pressed into service as a comparator; however, this is

not recommended for any rail-to-rail output op amps. For rail-

to-rail output op amps, the output stage is generally a ratioed

current mirror with bipolar or MOSFET transistors. With the part

operating open loop, the second stage increases the current drive

to the ratioed mirror to close the loop, but it cannot, which results

in an increase in supply current. With the op amp configured as

a comparator, the supply current can be significantly higher (see

Figure 48).

500

400

300

200

100

0

36

32

28

24

20

16

12

8

4

0

SUPPLY VOLTAGE (V)

BUFFER

Figure 48. Comparator Supply Current