Signal control device

A signal control device comprising:

• a signal input terminal to which an input signal with a voltage value fluctuating within a predetermined fluctuation range is input from an input circuit;
• a sampling capacitor having one end connected to the signal input terminal via an input signal path and another end connected to a reference potential;
• a charge/discharge circuit including a charge path provided from a charge power supply end to a second connection point on the input signal path via a first connection point, a discharge path provided from the second connection point to a reference potential end via the first connection point, a charge switch capable of switching electrical connection and electrical disconnection between the charge path and the sampling capacitor and capable of charging the sampling capacitor when the charge path and the sampling capacitor are electrically connected, and a discharge switch capable of switching electrical connection and electrical disconnection between the discharge path and the sampling capacitor and capable of discharging the sampling capacitor when the discharge path and the sampling capacitor are electrically connected;
• an AD conversion circuit performing an AD conversion by converting an analog voltage value charged in the sampling capacitor into an AD conversion value that is a digital value;
• a switch control circuit operating the charge switch and the discharge switch;
• and
• a malfunction determination section performing the AD conversion with the AD conversion circuit after performing a charge operation or a discharge operation to the sampling capacitor with the charge/discharge circuit, and determining a malfunction of the charge/discharge circuit based on a diagnosis result of the AD conversion value, wherein
• the malfunction determination section performs a charge/discharge circuit simultaneous check in which a malfunction of the charge switch or the charge path and a malfunction of the discharge switch or the discharge path are simultaneously diagnosed, and
• in the charge/discharge circuit simultaneous check, the malfunction determination section performs the AD conversion in a state where both of the charge switch and the discharge switch are turned on, and diagnoses the charge/discharge circuit as the malfunction when the AD conversion value is out of a specified range.

A signal control device comprising:

• a signal input terminal to which an input signal with a voltage value fluctuating within a predetermined fluctuation range is input from an input circuit;
• a sampling capacitor having one end connected to the signal input terminal via an input signal path and another end connected to a reference potential;
• a charge/discharge circuit including a charge path provided from a charge power supply end to a second connection point on the input signal path via a first connection point, a discharge path provided from the second connection point to a reference potential end via the first connection point, a charge switch capable of switching electrical connection and electrical disconnection between the charge path and the sampling capacitor and capable of charging the sampling capacitor when the charge path and the sampling capacitor are electrically connected, and a discharge switch capable of switching electrical connection and electrical disconnection between the discharge path and the sampling capacitor and capable of discharging the sampling capacitor when the discharge path and the sampling capacitor are electrically connected;
• an AD conversion circuit performing an AD conversion by converting an analog voltage value charged in the sampling capacitor into an AD conversion value that is a digital value;
• a switch control circuit operating the charge switch and the discharge switch;
• a malfunction determination section performing the AD conversion with the AD conversion circuit after performing a charge operation or a discharge operation to the sampling capacitor with the charge/discharge circuit, and determining a malfunction of the charge/discharge circuit based on a diagnosis result of the AD conversion value;
• and
• a control arithmetic operation section performing a predetermined control arithmetic operation based on at least a part of the AD conversion value obtained by the AD conversion circuit, wherein
• the signal input terminal is one of a plurality of signal input terminals, and the charge/discharge circuit is one of a plurality of charge/discharge circuits corresponding to the plurality of signal input terminals,
• when the malfunction determination section determines one or more of the plurality of charge/discharge circuits as the malfunction, the control arithmetic operation stops usage of the AD conversion value corresponding to the charge/discharge circuit determined as the malfunction, and performs the predetermined control arithmetic operation using only the AD convention value corresponding to the charge/discharge circuit determined as normal.