INA821 datasheet(27/43 Pages) TI2

Il numero della parte	INA821

Spiegazioni elettronici	INA818 35-μV Offset, 8-nV/√Hz Noise, Low-Power, Precision Instrumentation Amplifier

PDF	43 Pages

Scroll/Zoom	100%

Produttore elettronici	TI2 [Texas Instruments]

Homepage	https://www.ti.com

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27 / 43 page

+IN

±IN

INA818

5 V

OPA191

100 k

5 V

1 F

5 V

100 k

OUT

100

120

100

10k

0 Ω

10 Ω

5 Ω

15 Ω

20 Ω

Frequency (Hz)

INA818

www.ti.com

SBOS894A – APRIL 2019 – REVISED JUNE 2019

Product Folder Links: INA818

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Application Information (continued)

The parasitic resistance at the reference pin (RREF) creates an imbalance in the four resistors of the internal

difference amplifier, which degrades the common-mode rejection ratio (CMRR). Figure 66 shows the degradation

in CMRR of the INA818 as a result of increased resistance at the reference pin. For the best performance, keep

the source impedance to the REF pin (RREF) below 5 Ω.

Figure 66. The Effect of Increasing Resistance at the Reference Pin

Voltage-reference devices are a suitable option for providing a low-impedance voltage source for the reference

pin. However, if a resistor voltage divider generates a reference voltage, the divider must be buffered by an op

amp, as Figure 67 shows, in order to avoid CMRR degradation.

Figure 67. Using an Op Amp to Buffer Reference Voltages

INA821 Scheda tecnica(PDF) 27 Page - Texas Instruments