SBOS464A October 2019 – May 2020 INA333-Q1
The gain of the INA333-Q1 is set by a single external resistor, RG, connected between pins 1 and 8. The value of RG is selected according to Equation 1:
Table 1 lists several commonly-used gains and resistor values. The 100 kΩ in Equation 1 comes from the sum of the two internal feedback resistors of A1 and A2. These on-chip resistors are laser trimmed to accurate absolute values. The accuracy and temperature coefficient of these resistors are included in the gain accuracy and drift specifications of the INA333-Q1.
The stability and temperature drift of the external gain setting resistor, RG, also affects gain. The contribution of RG 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 and contribute additional gain error (possibly an unstable gain error) in gains of approximately 100 or greater. To maintain stability, avoid parasitic capacitance greater than a few picofarads at the RG connections. Careful matching of any parasitics on both RG pins maintains optimal CMRR over frequency.
|DESIRED GAIN||RG (Ω)||NEAREST 1% RG (Ω)|