Self-test circuit, and corresponding device, vehicle and method

An electrically-propelled vehicle comprising:

• an electrical battery pack including a plurality of battery cells;
• a differential stage having a first input node and a second input node, the differential stage having a first output node and a second output node configured to provide a differential output signal therebetween;
• an analog-to-digital converter coupled to the first and second output nodes of the differential stage, the analog-to-digital converter configured to provide an output signal that is a function of the differential output signal from the differential stage;
• a multiplexer having a first input terminal and a second input terminal that is coupled to one of the battery cells of the electrical battery pack, wherein the multiplexer comprises a test switch switchable between a conductive state and a non-conductive state, wherein the test switch in the conductive state couples the first input node and the second input node of the differential stage;
• test signal injection circuitry activatable to force a differential current through the differential stage;
• wherein the test signal injection circuitry is selectively switchable between an operational mode and a self-test mode;
• wherein, in the operational mode, the test switch is in the non-conductive state and the multiplexer is configured to transfer a differential input signal to the first input node and the second input node of the differential stage and the test signal injection circuitry is inactive, wherein the differential output signal from the differential stage comprises a replica of the differential input signal;
• and
• wherein, in the self-test mode, the test switch is in the conductive state and the test signal injection circuitry is active, wherein the differential output signal from the differential stage is a function of the differential current forced through the differential stage by the test signal injection circuitry.

A method of operating a circuit, wherein:

• the circuit comprises:
• a differential stage having a first input node and a second input node, the differential stage having a first output node and a second output node configured to provide a differential output signal therebetween;
• an analog-to-digital converter coupled to the first and second output nodes of the differential stage, the analog-to-digital converter configured to provide an output signal that is a function of the differential output signal from the differential stage;
• a multiplexer comprising a first input terminal and a second input terminal configured to receive a differential input signal therebetween, the multiplexer also comprising a test switch switchable between a conductive state and a non-conductive state, wherein the test switch in the conductive state couples the first input node and the second input node of the differential stage;
• and,
• test signal injection circuitry activatable to force a differential current through the differential stage;
• the method comprises switching the circuit between:
• an operational mode, with the test switch in the non-conductive state and the multiplexer configured to transfer the differential input signal to the first input node and the second input node of the differential stage and the test signal injection circuitry is inactive, wherein the differential output signal from the differential stage comprises a replica of the differential input signal;
• and
• a self-test mode, with the test switch in the conductive state and the test signal injection circuitry active, wherein the differential output signal from the differential stage is a function of the differential current forced through the differential stage by the test signal injection circuitry.