ADA4610S

ASD0016547 Rev. A | Page 16 of 18

7.3. INPUT OVERVOLTAGE PROTECTION

The ADA4610 have internal protective circuitry that allows voltages as high as 0.7 V beyond the supplies to

be applied at the input of either terminal without causing damage. For higher input voltages, a series resistor

is necessary to limit the input current. The resistor value can be determined from the formula

mA

R

V

V

S

S

IN

5

≤

−

7.4. COMPARATOR OPERATION

Although op amps are quite different from comparators, occasionally an unused section of a dual or a quad op

amp may be used as a comparator; however, this is not recommended for any rail-to-rail output op amp. 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. However, the second stage cannot close the loop, 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 44). Configuring an unused section as a voltage follower with the noninverting input connected to

a voltage within the input voltage range is recommended. The ADA4610 has a unique output stage design

that reduces the excess supply current, but does not entirely eliminate this effect when the op amp is

operating open loop.