INA350 datasheet(20/45 Pages) TI

20 / 45 page

8.3 Feature Description

8.3.1 Gain-Setting

The gain equation of INA350ABS can be given by Equation 1:

G = 1+180 kΩRG

(1)

The value of the internal gain resistor RG for INA350ABS can then be derived from the gain equation:

RG = 180 kΩG − 1

(2)

Similarly The gain equation of INA350CDS can be given by Equation 1:

G = 1+290 kΩRG

(3)

The value of the internal gain resistor RG for INA350CDS can then be derived from the gain equation:

RG = 290 kΩG − 1

(4)

Gain selection table below outlines how to choose different gain options across INA350ABS and INA350CDS.

The 60-kΩ, 90-kΩ, and 145-kΩ resistors mentioned are all typical values of the on-chip resistors.

Table 8-1. Gain Selection Table

DEVICE

GAIN SELECT (GS)

SELECTED GAIN

INA350ABS

High or No Connect

Low

INA350CDS

High or No Connect

Low

8.3.1.1 Gain Error and Drift

Gain error in INA350 is limited by the mismatch of the integrated precision resistors and it is specified based

on characterization results. Gain error of maximum 0.5% can be expected for the gains of 10 and 0.6% for the

gains of 20, 30 and 50. Gain drift in INA350 is limited by the slight mismatch of the temperature coefficient of

the integrated resistors. Since these integrated resistors are precision matched with low temperature coefficient

resistors to begin with, the overall gain drift would be much better in comparison to discrete implementation of

the instrumentation amplifiers built using external resistors.

8.3.2 Input Common-Mode Voltage Range

INA350 has two gain stages, the first stage has a common-mode gain of 1 and a differential gain set by the GS

pin. The second stage is configured in a difference-amplifier configuration with differential gain of 1 and ideally

rejects all of the input common mode completely. The second stage also provides a gain of 1 from REF pin to set

the output common-mode voltage.

The linear input voltage range of the INA350, even for a rail-to-rail first stage is dictated by the signal swing at

output of the first stage as well as the input common-mode voltage range output swing of the second stage. It is

imperative that the INA350 stays linear for a particular combination of gain, reference, and input common-mode

voltage for a chosen input differential. Input common-mode voltage (VCM) vs output voltage graphs (VOUT) in this

section show a particular reference voltage and gain configuration to outline the linear performance region of

INA350. A good common-mode rejection can be expected when operating with in the limits of the VCM vs VOUT

graph. Note, that the INA350 linear input voltage cannot be close to or extend beyond the supply rails as the

output of the first stage will be driven into saturation.

The common-mode range for the most common operating conditions is outlined below. Figure 8-1 shows the

region of operation where a minimum of 85 dB can be achieved. Figure 8-2 has much wider region of operation

INA350

SBOSAA0A – NOVEMBER 2021 – REVISED DECEMBER 2021

www.ti.com

Submit Document Feedback

Product Folder Links: INA350

INA350 Datasheet(PDF) 20 Page - Texas Instruments

INA350 Datasheet(HTML) 20 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

Datasheet Download

Link URL