Methods and apparatus to implement current sensors

An apparatus comprising:

• a first input terminal, a second input terminal, and an output terminal;
• an amplifier including a first input terminal and a second input terminal;
• a multiplexer configured to:
• connect the first input terminal to the first input terminal of the amplifier based on a polarity signal being a first voltage, the polarity signal corresponding to a direction of a first current;
• and
• connect the second input terminal to the first input terminal of the amplifier based on the polarity signal being a second voltage;
• and
• the amplifier configured to:
• based on (a) the first current between the first input terminal and the second input terminal flowing in a first direction and (b) the multiplexer connection the first input terminal to the first input terminal of the amplifier, operate as an amplifier to cause sinking of a second current through the output terminal;
• and
• after the first current changes to a second direction opposite the first direction, operate as a comparator to cause the polarity signal to change to the second voltage.

A system comprising:

• a first battery configured to provide first power to a load;
• a second battery configured to provide second power to the load;
• a switch coupled to the first battery and the second battery, the switch configured to, based on a control signal, connect or disconnect at least one of the first battery from the load or the second battery from the load;
• and
• a current sensor to generate the control signal, the current sensor including:
• a first sensor input terminal and a second sensor input terminal;
• and
• an amplifier configured to:
• operate as an amplifier to determine an amount of current between the first sensor input terminal and the second sensor input terminal;
• and
• operate as a comparator to determine a direction of the current between the first sensor input terminal and the second sensor input terminal, the control signal corresponding to at least one of the amount of current or the direction of the current.

A current sensor comprising:

• a first input terminal and a second input terminal;
• an amplifier including a first input terminal and a second input terminal;
• polarity detection circuitry to output a polarity signal based on an output of the amplifier, the output of the amplifier corresponding to whether the amplifier is in regulation;
• a first multiplexer configured to:
• connect the first input terminal (202) to the first input terminal (+) of the amplifier based on the polarity signal being a first voltage (high), the polarity signal corresponding to a direction of a current between the first input terminal and the second input terminal;
• and
• connect the second input terminal (204) to the first input terminal (+) of the amplifier based on the polarity signal being a second voltage (low);
• and
• a second multiplexer to:
• connect the first input terminal to the second input terminal of the amplifier based on the polarity signal being the second voltage;
• and
• connect the second input terminal to the second input terminal of the amplifier based on the polarity signal being the first voltage.