OPA656SLASH7 datasheet(9/26 Pages) TI2

9 / 26 page

OPA381

OPA2381

SBOS313B − AUGUST 2004 − REVISED NOVEMBER 2004

www.ti.com

OUTPUT RANGE

The OPA381 is specified to swing within at least 600mV

of the positive rail and 50mV of the negative rail with a

10k

Ω load while maintaining good linearity. Swing to the

negative rail while maintaining linearity can be extended

to 0V—see the section, Achieving Output Swing to

Ground. See the Typical Characteristic curve, Output

Voltage Swing vs Output Current.

The OPA381 can swing slightly closer than specified to

the positive rail; however, linearity will decrease and a

high-speed overload recovery clamp limits the amount

of positive output voltage swing available—see

Figure 2.

−5

−10

−15

−20

−25

OUT (V)

−1

456

S =5.5V

P =10kΩ to −5V

L = 10kΩ to VS/2

Figure 2. Effect of High-Speed Overload

Recovery Clamp on Output Voltage

OVERLOAD RECOVERY

The OPA381 has been designed to prevent output

saturation. After being overdriven to the positive rail, it

will typically require only 200ns to return to linear

operation. The time required for negative overload

recovery is greater, unless a pulldown resistor

connected to a more negative supply is used to extend

the output swing all the way to the negative rail—see the

following section, Achieving Output Swing to Ground.

ACHIEVING OUTPUT SWING TO GROUND

Some applications require output voltage swing from

0V to a positive full-scale voltage (such as +4.096V)

with excellent accuracy. With most single-supply op

amps,

problems

arise

when

the

output

signal

approaches 0V, near the lower output swing limit of a

single-supply op amp. A good single-supply op amp

may swing close to single-supply ground, but will not

reach 0V.

The output of the OPA381 can be made to swing to 0V,

or slightly below, on a single-supply power source. This

extended output swing requires the use of another

resistor and an additional negative power supply. A

pulldown resistor may be connected between the

output and the negative supply to pull the output down

to 0V; see Figure 3.

OPA381

OUT

P =10kΩ

V+=+5V

− =Gnd

−V

S = − 5V

Negative Supply

P =

−V

500

µA

Figure 3. Amplifier with Pull-Down Resistor to

Achieve VOUT = 0V

The OPA381 has an output stage that allows the output

voltage to be pulled to its negative supply rail using this

technique. However, this technique only works with

some types of output stages. The OPA381 has been

designed to perform well with this method. Accuracy is

excellent down to 0V. Reliable operation is assured over

the specified temperature range.

OPA656/7 Datasheet(PDF) 9 Page - Texas Instruments

OPA656/7 Datasheet(HTML) 9 Page - Texas Instruments

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 25 26

Datasheet Download

Link URL