AD8278ARMZ-R7 datasheet(17/24 Pages) AD

17 / 24 page

AD8278

Rev. 0 | Page 17 of 24

POWER SUPPLIES

The AD8278 operates extremely well over a very wide range of

supply voltages. It can operate on a single supply as low as 2 V

and as high as 36 V, under appropriate setup conditions.

For best performance, the user must exercise care that the setup

conditions ensure that the internal op amp is biased correctly.

The internal input terminals of the op amp must have sufficient

voltage headroom to operate properly. Proper operation of the

part requires at least 1.5 V between the positive supply rail and

the op amp input terminals. This relationship is expressed in

the following equation:

−

REF

For example, when operating on a +VS= 2 V single supply and

VREF = 0 V, it can be seen from Figure 47 that the op amps input

terminals are biased at 0 V, allowing more than the required 1.5 V

headroom. However, if VREF = 1 V under the same conditions, the

input terminals of the op amp are biased at 0.66 V (G = ½). Now

the op amp does not have the required 1.5 V headroom and can

not function. Therefore, the user needs to increase the supply

voltage or decrease VREF to restore proper operation.

The AD8278 is typically specified at single- and dual-supplies,

but it can be used with unbalanced supplies as well; for example,

−VS = −5 V, +VS = 20 V. The difference between the two supplies

must be kept below 36 V. The positive supply rail must be at

least 2 V above the negative supply and reference voltage.

R1 + R2

(VREF)

R1 + R2

(VREF)

VREF

Figure 47. Ensure Sufficient Voltage Headroom on the Internal Op Amp

Inputs

Use a stable dc voltage to power the AD8278. Noise on the

supply pins can adversely affect performance. Place a bypass

capacitor of 0.1 μF between each supply pin and ground, as

close as possible to each supply pin. Use a tantalum capacitor

of 10 μF between each supply and ground. It can be farther

away from the supply pins and, typically, it can be shared by

other precision integrated circuits.

AD8278ARMZ-R7 Datasheet(PDF) 17 Page - Analog Devices

AD8278ARMZ-R7 Datasheet(HTML) 17 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Datasheet Download

Link URL