CELL BALANCING CIRCUIT, METHOD OF DRIVING THE SAME, AND BATTERY MANAGEMENT SYSTEM THAT INCLUDES THE CELL BALANCING CIRCUIT

1 . A cell balancing circuit comprising:

a reference voltage generator coupled in parallel to at least one battery and configured to generate a reference voltage;

a comparator for comparing a voltage output from a terminal of the at least one battery with the reference voltage; and

a switch coupled in series to the at least one battery through a discharge resistor, the switch being configured to discharge a current from the at least one battery, when turned on in response to a signal output from the comparator, through the discharge resistor.

2 . The cell balancing circuit of claim 1 , wherein the reference voltage comprises a first reference voltage, and the cell balancing circuit is configured to determine whether or not the battery is overcharged based on the first reference voltage.

3 . The cell balancing circuit of claim 2 , wherein the comparator is configured to output a first voltage signal when the voltage of the at least one battery is greater than the first reference voltage.

4 . The cell balancing circuit of claim 1 , further comprising a resistor coupled between the comparator and the switch.

5 . The cell balancing circuit of claim 1 ,

wherein the at least one battery comprises at least two batteries;

wherein the comparator comprises:

at least two comparators for respectively comparing battery voltages output from respective terminals of the at least two batteries with at least two reference voltages output from the reference voltage generator; and

wherein the discharge resistor comprises:

at least two discharge resistors respectively coupled in parallel to the at least two batteries.

6 . The cell balancing circuit of claim 5 , wherein the at least two batteries are independently cell-balanced through the at least two discharge resistors respectively.

7 . The cell balancing circuit of claim 5 , further comprising a charge pump coupled between the reference voltage generator and at least one of the at least two comparators.

8 . The cell balancing circuit of claim 1 , wherein the reference voltage generator comprises a low dropout (LDO) regulator or a regulator.

9 . A battery management system (BMS) comprising:

a reference voltage generator coupled in parallel to a plurality of battery cells and configured to generate a reference voltage;

a plurality of comparators respectively coupled to terminals of the battery cells and an output terminal of the reference voltage generator;

a plurality of transistors respectively coupled to the comparators; and

a plurality of discharge resistors respectively coupled between the terminals of the battery cells and the plurality of transistors.

10 . The BMS of claim 9 , further comprising at least one charge pump coupled between the reference voltage generator and at least one of the plurality of comparators.

11 . The BMS of claim 9 , further comprising a plurality of first resistors respectively coupled between the plurality of comparators and the plurality of transistors.

12 . The BMS of claim 9 , wherein the BMS is configured to determine whether or not the batteries are overcharged based on the reference voltage.

13 . The BMS of claim 9 , wherein the BMS is configured to cell-balance the battery cells based on the reference voltage.

14 . The BMS of claim 9 , wherein each of the comparators is configured to turn on a corresponding one of the transistors by outputting a voltage signal when a voltage of a corresponding one of the batteries is greater than the reference voltage.

15 . A method of driving a cell balancing circuit, the method comprising:

generating a reference voltage;

comparing a battery voltage output from a battery with the reference voltage;

outputting a signal according to the comparison result;

turning on a transistor in response to the output signal; and

discharging a current from the battery through a discharge resistor coupled in series to the battery.