6 Application and Implementation

Note

Information in the following applications sections is not part of the TI component specification,

and TI does not warrant its accuracy or completeness. TI’s customers are responsible for

determining suitability of components for their purposes, as well as validating and testing their design

implementation to confirm system functionality.

6.1 Application Information

The INA146 is a programmable gain difference amplifier consisting of a gain of 0.1 difference amplifier and a

programmable-gain output buffer stage. Basic circuit connections are shown in Figure 6-1. Power supply bypass

capacitors must be connected close to pins 4 and 7, as shown. The amplifier is programmable in the range of G

= 0.1 to G = 50 with two external resistors.

The output of A1 is connected to the noninverting input of A2 through a 10-kΩ resistor which is trimmed to ±1%

absolute accuracy. The A2 input is available for applications such as a filter or a precision current source. See

application figures for examples.

6.1.1 Operating Voltage

The INA146 is fully specified for supply voltages from ±2.25 V to ±18 V with key parameters specified over

the temperature range –40°C to 85°C. The INA146 can be operated with single or dual supplies with excellent

performance. Parameters that vary significantly with operating voltage, load conditions or temperature are shown

in the typical performance curves.

6.1.2 Setting the Gain

The gain of the INA146 is set by using two external resistors, RG1 and RG2, according to the equation:

G = 0.1 × (1 + RG2/RG1)

For a total gain of 0.1, A2 is connected as a buffer amplifier with no RG1. A feedback resistor, RG2 = 10 kΩ,

must be used in the buffer connection. This provides bias current cancellation (in combination with internal R5)

to assure specified offset voltage performance. Commonly used values are shown in the table of Figure 6-1.

Resistor values for other gains must be chosen to provide a 10-kΩ parallel resistance.

6.1.3 Common-mode Range

The 10:1 input resistor ratio of the INA146 provides an input common-mode range that can extend well beyond

the power supply rails. Exact range depends on the power supply voltage and the voltage applied to the Ref

terminal (pin 1). For proper operation, the voltage at the non-inverting input of A1 (an internal node) must be

within the linear operating range. The voltage is determined by the simple 10:1 voltage divider between pin 3 and

pin 1. This voltage must be between V– and (V+) – 1 V.

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INA146

SBOS109A – SEPTEMBER 1999 – REVISED NOVEMBER 2023

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