Datasheet

PGA400 EVM User Guide
TI CONFIDENTIAL – NDA Restrictions
Page 28 of 50
7.2.1.5 Stage 1 Gain Select
The “Stage 1 Gain Select” combo-box controls bits 5-7 of either register 0xA1 or 0xA2
depending on the state of the “Sensor Select” combo-box
7.2.1.6 Stage 2 Gain Select
The “Stage 2 Gain Select” combo-box controls bits 0-4 of either register 0xA1 or 0xA2
depending on the state of the “Sensor Select” combo-box
7.2.2 Capacitive AFE Tab
The capacitive AFE tab is not activated by default when the GUI loads. The user can select the
capacitive tab and then enable the capacitive AFE to begin evaluating the capacitive signal
chain on the PGA400-Q1. An image of the capacitive AFE tab along with a description of the
buttons can be found below.
Figure 21. Capacitive AFE Tab
7.2.2.1 Activate Capacitive AFE
The “Activate Capacitive AFE” button configures the PGA400-Q1 for the Resistive AFE by
controlling bit 7 in ESFR 0xA7.
7.2.2.2 Drive Voltage
The “Drive Voltage” selection boxes control the voltage on the clock generator comparator in the
PGA400-Q1 by controlling bits 2 and 3 in ESFR 0xA7.
7.2.2.3 Drive Current Select
The “Drive Current Select” selection boxes control the current that is switched in and out of the
ICAP pins by controlling bits 4-6 in ESFR 0xA7.