13

INA148-Q1

www.ti.com

SBOS472B – MARCH 2009 – REVISED JUNE 2016

Product Folder Links: INA148-Q1

Submit Documentation Feedback

Copyright © 2009–2016, Texas Instruments Incorporated

Feature Description (continued)

Source impedances (or shunts) greater than 5 k

Ω are not recommended, even if they are perfectly compensated.

This is because the internal resistor network is laser-trimmed for accurate voltage divider ratios, but not

necessarily to absolute values. Input resistors are shown as 1 M

Ω; however, this is only their nominal value.

In practice, the input resistors' absolute values may vary by as much as 30%. The two input resistors match to

about 5%, so adding compensating resistors greater than 5 k

Ω can cause a serious mismatch in the resulting

resistor network voltage divider ratios, thus degrading CMR.

TI recommends not attempting to extend the INA148-Q1 input voltage range by adding external resistors for the

reasons described in the previous paragraph. CMR suffers serious degradation unless the resistors are carefully

trimmed for CMR and gain. This is an iterative adjustment and can be tedious and time consuming.

7.4 Device Functional Modes

The INA148-Q1 is a unity-gain, differential to single-ended amplifier that can reject high common-mode signals

up to ±200 V with ±15-V supply voltage. This high common-mode rejection is achieved by internal trimmed

resistive divider network. The resistive network provides an attenuation factor of 20:1.

Equation 2 shows the transfer function output to input.

VO = V+IN – V–IN

(2)