The Programmable Gain Amplifier (PGA) is an electronic amplifier with gain that can be controlled through certain parameters. The PGA is connected directly to the ADC and has various Modes, Gain and Input options.
Turns PGA on or off, given ADC is off. Note that if ADC is powered-on, PGA is always forced on, even if Power down is applied here.
There are seven gain values to choose from, x0.25, x0.5, x1, x2, x4, x8 an x16. Available gain settings are different for different operating modes as below:
• Single-ended: x0.25, x0.5, x1, x2, x4, x8;
• Differential: x1, x2, x4, x8, x16;
• Pseudo-differential: x1, x2, x4;
• Single-ended: gain is applied to IN+ (Channel 1 or Channel 2) with reference to GND;
• Differential: gain is applied to the difference between IN+ (Channel 1 only) and IN- and given with an offset of 550 mV. e.g. Output is 550 mV when difference is zero. IN+ can be above or below IN-;
• Pseudo-differential: gain is applied to the difference between IN+ (Channel 1 only) and IN- with an offset of 180 mV. Output is 180 mV when difference is zero. Operating range assumes IN+ is always above IN-;
“Force analog part” option in ADC should be enabled or ADC should be turned on for PGA to operate in Differential and Pseudo-differential modes.
Available in Single-ended mode only, the channel selector is a digital input where HIGH selects IN+ Channel1 and LOW selects IN+ Channel 2.
• VDD: enables only IN+ Channel 1;
• PIN16: is an external selector input to choose between IN+ Channel1 and IN+ Channel 2;
Analog Input to the PGA IN+ Channel 1 available from two external sources.
• PIN8 Analog input;
• PIN9 Analog input;
Analog Input to the PGA IN+ Channel 2 available from two external sources.
• PIN8 Analog input;
• PIN9 Analog input;
Analog Input to the PGA IN- Channel available from an internal or external source.
• PIN9 Analog input;
• DAC0 out Analog input;
Enable/Disable PIN7 as analog output of the PGA. For proper functionality, PIN7 must be configured as Analog input/output.