9.2.2 Detailed Design Procedure

9.2.2.1 Reference Pin

The output voltage of the INA848 is developed with respect to the voltage on the reference pin (REF.)

Any additional resistance at the reference pin creates an imbalance in the four resistors of the internal difference

amplifier, resulting in degraded common-mode rejection ratio (CMRR).

Voltage reference devices are an excellent 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 shown in Figure 9-5, to avoid CMRR degradation.

+

±

100 k

100 k

5 V

5 V

í5 V

1 …F

OUT

INA848

REF

+IN

íIN

5 V

Figure 9-5. Buffer to drive the Reference Voltage

Often in dual-supply operation, the reference pin connects to the low-impedance system ground. The

referred to the reference pin (REF).

In single-supply operation, the output signal is offset to a precise midsupply level (for example, 2.5 V in a 5-V

supply environment). In applications where the output voltage is offset to a reference voltage but referred to

system ground, the degradation effect of common-mode rejection ratio must be considered.

INA848

SBOS946 – SEPTEMBER 2020

www.ti.com

20

Submit Document Feedback

Copyright © 2020 Texas Instruments Incorporated

Product Folder Links: INA848