Software
17
SLDU031 – December 2017
Copyright © 2017, Texas Instruments Incorporated
PGAxxxEVM-037 Pressure Sensor Signal Conditioner Evaluation Module
4.5.2
Input Signal MUX Select and Additional Settings
The MUX select setting allows the user to choose the input type of the signal connected to the VINPP and
VINPN pins of the device. For a differential signal, select VINPP – VINPN, and for single-ended signals
the user can choose either VINPP – 1.25 V, or 1.25 V – VINPN depending on which of the input pins the
signal is connected to. The
Single Ended Input
box must also be selected if using a single-ended input
signal. Additionally, the input signal can be inverted if desired by checking the
Invert Signal
box. The
Single Ended Input
and
Invert Signal
check boxes are available for both the P Gain and T Gain input
blocks, and can be configured separately.
4.5.3
P Channel and T Channel
Both the P Channel and T Channel blocks have adjustable gains with a range of 1.33 V/V up to 200 V/V
to properly amplify any input signal to take advantage of the full input range of the ADC.
4.5.4
P/T Channel Select
The
P/T Channel MUX Select
allows the user to determine which input signals are directed to the ADC of
the PGAxxx device. In fixed-channel mode, either the P Channel or T Channel inputs can be directed to
the ADC for sampling. The
Auto Scan
mode allows the ADC to sample from both the P Channel and the T
Channel at user-defined intervals.
4.5.5
T Channel MUX Select
The T Channel MUX Select allows the user to determine which signals will be passed through the T
Channel to the ADC for sampling. The VINTP and VINTN pin option can be selected for use with an
external temperature sensor, or other sensor. To use the internal temperature sensor of the PGAxxx
device, select the
Internal Temp Sense
option. The
Bridge Current
option allows the user to read the
current through the internal VBRG voltage supply of the PGAxxx device. Additionally, the TEST1 pin can
be MUXed through to monitor a variety of internal signals for debugging purposes. The output of the
TEST1 pin can be set on the
Test Mode
page (see
). Finally, the DACCAP pin can be used
as an additional input if desired, and can be sent through the MUX to the ADC for sampling.
4.5.6
Block Enable Check Boxes
There are several block enable check boxes on the analog front end page. The ITEMP enable box will
turn on and connect the internal temperature sensor current source for use with external temperature
sensors that need current excitation. The VBRG enable box activates the internal bridge voltage supply to
provide voltage excitation for resistive bridge pressure sensors. The ADC is enabled with a check box,
and finally the DACCAP can be connected with an enable check box to provide a low-pass filter to the
DAC output buffer.
4.5.7
ITEMP Select
ITEMP select gives the user the option to select the current output of the ITEMP internal current source.
The current source can supply 50 to 1000 µA, or it can be disabled with this control.
4.6
Output DAC Page
illustrates the output DAC page.
