1 MW

50 kW

52.6316 kW

50 kW

2.7778 kW

1 MW

V

+IN

7

3

2

6

4

1

A1

INA148-Q1

–V

S

V

O

V

–IN

0.1 µF

+V

S

0.1 µF

V = (V

– V

)

O

+IN

–IN

Copyright © 2016, Texas Instruments Incorporated

10

INA148-Q1

SBOS472B – MARCH 2009 – REVISED JUNE 2016

www.ti.com

Product Folder Links: INA148-Q1

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Copyright © 2009–2016, Texas Instruments Incorporated

7 Detailed Description

7.1 Overview

The INA148-Q1 is a unity-gain difference amplifier with a high common-mode input voltage range. To achieve its

high common-mode voltage range, the INA148-Q1 features a precision, laser-trimmed, thin-film resistor network

with a 20:1 input voltage divider ratio. High input voltages are thereby reduced in amplitude, delivering input

voltages to the op amp that are within its linear operating range. A Tee network in the op amp feedback network

places the amplifier in a gain of 20 V/V, restoring the overall circuit gain to unity (1 V/V).

External voltages can be summed into the amplifier's output by using the REF pin, making the differential

amplifier a highly versatile design tool. Voltages on the REF pin also influence the INA148-Q1's common-mode

voltage range.

In accordance with good engineering practice for linear integrated circuits, the INA148-Q1's power-supply bypass

capacitors must be connected as close to the supply pins (V+ and V–) as practical. TI recommends ceramic or

tantalum capacitors for use as bypass capacitors.

The input impedances are unusually high for a difference amplifier and this must be considered when routing

input signal traces on a PCB. Avoid placing digital signal traces near the difference amplifier's input traces to

minimize noise pickup.

7.2 Functional Block Diagram

7.3 Feature Description

7.3.1 Operating Voltage

The INA148-Q1 is specified for ±15-V and ±5-V dual supplies and 5-V single supplies. The INA148-Q1 can be

operated with single or dual supplies with excellent performance.

The INA148-Q1 is fully characterized for supply voltages from ±1.35 V to ±18 V and over temperatures of –40°C

to 125°C. Parameters that vary significantly with operating voltage, load conditions, or temperature are shown in

Typical Characteristics.

7.3.2 Gain Equation

An internal on-chip resistor network sets the overall differential gain of the INA148-Q1 to precisely 1 V/V.

Equation 1 shows the output.

VO = (V+IN – V–IN) + VREF

(1)