Temperature measurement techniques for battery management circuits

A method of measuring a temperature-dependent voltage drop over a temperature sensitive resistor via a temperature measurement circuit that includes:

• a reference voltage supply circuit configured to supply a reference voltage;
• a first current source configured to supply a temperature measurement current;
• a current mirror comprising a plurality of outputs, wherein the current mirror includes a first transistor and a plurality of second transistors connected to a plurality of second current sources that source different current levels in the current mirror to the plurality of outputs;
• and
• a switch circuit configured to select between the reference voltage supply circuit and the first current source,
• the method comprising:
• delivering a reference voltage to the temperature sensitive resistor in a first instance of time;
• determining an auto-ranging current through the temperature sensitive resistor based on the plurality of outputs while the reference voltage is delivered to the temperature sensitive resistor, wherein the current mirror is configured to define the auto-ranging current through the temperature sensitive resistor based on the plurality of outputs;
• determining a temperature measurement current based on the auto-ranging current;
• delivering the temperature measurement current to the temperature sensitive resistor in a second instance of time, wherein the second instance of time is after the first instance of time;
• and
• measuring the temperature-dependent voltage drop over the temperature sensitive resistor while the temperature measurement current is delivered to the temperature sensitive resistor.

A system comprising:

• a plurality of battery cells;
• and
• a plurality of battery management circuits configured to manage different subsets of the plurality of battery cells, wherein each of the battery management circuits includes one or more temperature measurement circuits, wherein each of the temperature measurement circuits is configured to measure a temperature-dependent voltage drop over a temperature sensitive resistor and wherein each of the temperature measurement circuits comprises:
• a reference voltage supply circuit configured to supply a reference voltage;
• a first current source configured to supply a temperature measurement current;
• a current mirror comprising a plurality of outputs, wherein the current mirror includes a first transistor and a plurality of second transistors connected to a plurality of second current sources that source different current levels in the current mirror to the plurality of outputs;
• and
• a switch circuit configured to select between the reference voltage supply circuit and the first current source, wherein each of the temperature measurement circuits is configured to:
• control the switch circuit to deliver the reference voltage to the temperature sensitive resistor;
• determine an auto-ranging current through the temperature sensitive resistor based on the plurality of outputs of the current mirror while the reference voltage is delivered to the temperature sensitive resistor, wherein the current mirror is configured to define the auto-ranging current through the temperature sensitive resistor based on the plurality of outputs;
• determine the temperature measurement current based on the auto-ranging current;
• control the switch circuit to deliver the temperature measurement current to the temperature sensitive resistor;
• and
• measure the temperature-dependent voltage drop over the temperature sensitive resistor while the temperature measurement current is delivered to the temperature sensitive resistor.