Users Manual

Table Of Contents
R01UH0823EJ0110 Rev.1.10 Page 1628 of 1852
Nov 30, 2020
RX23W Group 44. 12-Bit A/D Converter (S12ADE)
44.3.9 Disconnection Detection Assist Function
This converter incorporates the function to fix the charge for sampling capacitance to the specified state (reference
voltage selected by the A/D high-potential/low-potential reference voltage control register) before start of A/D
conversion. This function enables disconnection detection in wiring of analog inputs.
Figure 44.24 illustrates the A/D conversion operation when the disconnection detection assist function is used. Figure
44.25
shows an example of disconnection detection when precharge is selected. Figure 44.26 shows an example of
disconnection detection when discharge is selected.
Figure 44.24 Operation of A/D Conversion When the Disconnection Detection Assist Function is Used
Figure 44.25 Example of Disconnection Detection When Precharge is Selected
ADST
A/D conversion
operation
Sampling time
Disconnection detection assist time (0 to 15 cycles of ADCLK)
Conversion time Sampling time
Disconnection detection assist time (0 to 15 cycles of ADCLK)
Conversion time
Precharge
control signal
Discharge
control signal
Analog input
ANn
ON
OFF
R = 1 MΩ
Disconnection
Sampling capacitance
Example of the
external circuit
*1
Precharge
VREFH0
or AVCC0
Note 1. The converted result should be used after fully evaluated because the result data when disconnection
occurs varies depending on the external circuit.