ZHCSJM1A April 2019 – June 2019 INA818
PRODUCTION DATA.
8.3.1 Setting the Gain
Figure 55 shows that the gain of the INA818 is set by a single external resistor (RG) connected between the RG pins (pins 1 and 8).
Figure 55. Simplified Diagram of the INA818 With Gain and Output Equations The value of RG is selected according to Equation 1:
Table 2 lists several commonly-used gains and resistor values. The 50-kΩ term in Equation 1 comes from the sum of the two internal 25-kΩ feedback resistors. These on-chip resistors are laser-trimmed to accurate absolute values. The accuracy and temperature coefficients of these resistors are included in the gain accuracy and drift specifications of the INA818. As shown in Figure 55 and explained in more details in the Layout section, make sure to connect low-ESR, 0.1-µF ceramic bypass capacitors between each supply pin and ground that are placed as close to the device as possible.
Table 2. Commonly-Used Gains and Resistor Values
| DESIRED GAIN | RG (Ω) | NEAREST 1% RG (Ω) |
|---|---|---|
| 1 | NC | NC |
| 2 | 50 k | 49.9 k |
| 5 | 12.5 k | 12.4 k |
| 10 | 5.556 k | 5.49 k |
| 20 | 2.632 k | 2.61 k |
| 50 | 1.02 k | 1.02 k |
| 100 | 505.1 | 511 |
| 200 | 251.3 | 249 |
| 500 | 100.2 | 100 |
| 1000 | 50.05 | 49.9 |