SBOU315 March 2024 PGA849
The PGA849 provides eight binary gain settings, from an attenuating gain of 0.125V/V to a maximum of 16V/V. The gain is controlled by three digital selection pins: A0, A1, and A2. By default, the PGA849 is configured to a gain of 0.125V/V.
The evaluation board provides shunt jumpers J10, J11, and J12 to set the PGA849 gain-control selection pins. Table 3-4 lists the gain-control options. To set the gain-control pin high, install the shunt on the corresponding jumper. To set the gain-control pin low, remove the shunt jumper.
A2 Jumper J10 Connector J15.1 |
A1 Jumper J11 Connector J15.2 |
A0 Jumper J12 Connector J15.3 |
PGA Gain (V/V) |
---|---|---|---|
Low (Open) | Low (Open) | Low (Open) | 0.125 |
Low (Open) | Low (Open) | High (Shunt) | 0.25 |
Low (Open) | High (Shunt) | Low (Open) | 0.5 |
Low (Open) |
High (Shunt) |
High (Shunt) | 1 |
High (Shunt) |
Low (Open) |
Low (Open) | 2 |
High (Shunt) | Low (Open) | High (Shunt) | 4 |
High (Shunt) |
High (Shunt) |
Low (Open) | 8 |
High (Shunt) | High (Shunt) | High (Shunt) | 16 |
Alternatively, the A0, A1, and A2 digital pins can be driven externally through connector J15. Any pin that is not driven by an external source, or any shunt that is left open, is biased at DGND using pulldown resistors. Figure 3-6 shows the gain-setting block diagram.