Start
Tdischarge
Vreflo
Sampling time
Tsamp
ADINx
Sample cap discharge time
Conversion of last value sampled
ADC Special Modes
716
SPNU503C – March 2018
Copyright © 2018, Texas Instruments Incorporated
Analog To Digital Converter (ADC) Module
19.8.4 ADC Sample Capacitor Discharge Mode
This mode allows the charge on the ADC core’s internal sampling capacitor to be discharged before
starting the sampling phase of the next channel.
The ADC Sample Cap Discharge Mode is enabled by setting the SAMP_DIS_EN bit of the group’s
ADSAMPDISEN register. A discharge period for the sampling capacitor is added before the sampling
period for each channel as shown in
. The duration of this discharge period is configurable via
the corresponding group’s SAMP_DIS_CYC field in the ADSAMPDISEN register. The discharge time is
specified in terms of number of ADCLK cycles.
During the sample capacitor discharge period, the V
REFLO
reference voltage is connected to the input
voltage terminal of the ADC core. This allows any charge collected on the sampling capacitor from the
previous conversion to be discharged to ground. The V
REFLO
reference voltage is usually connected to
ground.
Figure 19-15. Timing for Sample Capacitor Discharge Mode