Gain is set by connecting an external resistor, R_G:

Commonly used gains and R_G resistor values are shown in Figure 8-1.

The 80-kΩ term in Equation 1 comes from the internal metal-film resistors, which are laser-trimmed to accurate absolute values. The accuracy and temperature coefficient of these resistors are included in the gain accuracy and drift specifications.

The stability and temperature drift of the external gain setting resistor, R_G, also affects gain. The R_G contribution to gain accuracy and drift can be directly inferred from Equation 1. Low resistor values required for high gain can make wiring resistance important. Sockets add to the wiring resistance, which contributes additional gain error in gains of approximately 100 or greater.