INA849 datasheet(23/52 Pages) TI

23 / 52 page

8.2 Functional Block Diagram

─IN

Current-

Feedback

Input Stage

Current-

Feedback

Input Stage

+IN

Fully Differential

Amplifier

OUT+

VOCM

External Gain Set

Resistor (Optional)

Overvoltage

Protection

Overvoltage

Protection

Input Bias

Current

Cancellation

Input Bias

Current

Cancellation

OUT─

FDA_IN─ (Optional)

FDA_IN+ (Optional)

G02+ (Optional, Externally

Short to OUT+ or Float)

G02─ (Optional, Externally

Short to OUT─ or Float)

LDO

VCLAMP+

LDO

VCLAMP─

8.3 Feature Description

8.3.1 Adjustable Gain Setting

Figure 8-2 shows that the INA851 input-stage gain is set by a single external resistor (RG) connected between

the RG pins. The gain of the output stage can be set to a unity gain of 1 V/V by floating the G02+ and G02– pins,

or to an attenuating gain of 0.2 V/V by shorting those pins to the respective OUT+ and OUT– pins.

–

OUT+

IN+

RG+

OUT

VOCM

G02

G02+

3 k

5 k

3 k

5 k

1.25 k

5 k

1.25 k

ADC

INP

INN

FDA_IN

FDA_IN+

–

INA851

–

VIN+

VIN

VO = G • (VIN+

VIN ) + VOCM

G = GIN * GOUT

Short OUT to G02 and

OUT+ to G02+ for output

stage G = 0.2 option

VOCM

GOUT = 0.2 or 1

GIN =

6 k

1 +

Figure 8-2. Simplified Diagram of the INA851 With Gain Equations

If the output stage is in the unity gain configuration, the value of RG is selected according to the following

equation:

G= 1+6kΩRG

(1)

When OUT+ is shorted to G02+ (pin 11 to pin 12) and OUT– is shorted to G02– (pin 9 to pin 10) so that the

output stage is in the attenuating configuration, the gain equation becomes:

G=0.2× 1+6kΩRG

(2)

Table 8-1 lists several commonly used gains and resistor values, as well as the additional gain error that is

contributed by the gain resistors. The 6-kΩ term in the gain equation is a result of the sum of the two internal

3-kΩ feedback resistors. These on-chip resistors are laser-trimmed to accurate absolute values. The accuracy

and temperature coefficients of these resistors are included in the gain accuracy and drift specifications of the

www.ti.com

INA851

SBOS999A – MARCH 2022 – REVISED OCTOBER 2022

Submit Document Feedback

Product Folder Links: INA851

INA849 датащи(PDF) 23 Page - Texas Instruments

INA849 датащи(HTML) 23 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 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52

датащи скачать

ссылки URL