Semiconductor device for protecting secondary battery, battery pack, and electronic device using same

1. A battery pack comprising:

a secondary battery:,

a discharge-control transistor;

a charge-control transistor connected in series with the discharge-control transistor between a negative lower source terminal of the secondary battery and either a terminal of a load or a negative power source terminal of a charger; and

a battery protection semiconductor device for protecting the secondary battery,

the battery protection semiconductor device comprising:

a detection circuit to detect at least one of an excessively charged state, an excessive discharging state, an overcurrent state, a short-circuit state, and an overheating state of the secondary battery;

a control circuit to turn on and off the discharge-control transistor and the charge-control transistor; and

a charge prevention circuit to prevent the secondary battery from being charged by turning off the charge-control transistor when a voltage of the secondary battery is not greater than a predetermined low-voltage criteria voltage that is variable by trimming a portion of the charge prevention circuit,

wherein the charge prevention circuit comprises:

a first inverter circuit that receives a high-level signal during a charging mode, connected to both the negative power source terminal and a positive power source terminal of the secondary battery; and

a second inverter circuit that receives an output from the first inverter circuit, connected to both the negative power source terminal and a positive power source terminal of the charger, and

wherein an input threshold voltage of the second inverter circuit is variable by trimming a portion of the second inverter circuit, and the charge-control transistor is turned off according to an output from the second inverter circuit when the voltage of the secondary battery is not greater than the low-voltage criterial voltage.

2. The battery pack according to claim 1 , wherein the input threshold voltage of the second inverter circuit is raised by trimming a portion thereof.

3. The battery pack according to claim 2 , wherein the second inverter circuit comprises:

a second PMOS transistor whose gate and source are connected to an output terminal of the first inverter circuit and the positive power source terminal of the charger, respectively;

a depression-type NMOS transistor whose gate is connected to the negative power source terminal of the charger;

at least one resistor connected serially between a source of the depression-type NMOS transistor and the negative power source terminal of the charger; and

a trimming fuse connected in parallel to each of the at least one resistor,

wherein a function node between drains of the second PMOS transistor and the depression-type NMOS transistor serves as an output terminal of the second inverter circuit.

4. The battery pack according to claim 2 , wherein the second inverter circuit comprises:

a second PMOS transistor whose gate and source are connected to an output terminal of the first inverter circuit and the positive power source terminal of the charger, respectively;

a first depression-type NMOS transistor whose gate, source, and back gate are connected to the negative power source terminal of the charger;

at least one second depression-type NMOS transistor whose gate and back gate are respectively connected to a source thereof and the negative voltage terminal of the charger, connected serially between a drain of the second PMOS transistor and a drain of the first depression-type NMOS transistor; and

a trimming fuse connected between a source and a drain of each of the at least one second depression-type NMOS transistor.

5. The battery pack according to claim 2 , wherein the second inverter circuit comprises:

a second PMOS transistor whose gate and source are connected to an output terminal of the first inverter circuit and the positive power source terminal of the charger, respectively;

a first depression-type NMOS transistor whose gate, source, and back gate are connected to the negative power source terminal of the charger;

at least one second depression-type NMOS transistor whose gate and back gate are respectively connected to the negative voltage terminal of the charger and a source thereof, connected serially between a drain of the second PMOS transistor and a drain of the first depression-type NMOS transistor; and

a trimming fuse connected between a source and a drain of each of the at least one second depression-type NMOS transistor.

6. The battery pack according to claim 2 , wherein the second inverter circuit comprises:

a second PMOS transistor whose gate and source are connected to an output terminal of the first inverter circuit and the positive power source terminal of the charger, respectively;

a first depression-type NMOS transistor whose gate, source, and back gate are connected to the negative power source terminal of the charger;

at least one second depression-type NMOS transistor whose gate and back gate are connected to the negative voltage terminal of the charger, connected serially between a drain of the second PMOS transistor and a drain of the first depression-type NMOS transistor; and

a trimming fuse connected between a source nd a drain of each of he at least one second depression-type NMOS transistor.

7. The battery pack according to claim 1 , wherein the input threshold voltage of the second inverter circuit is lowered by trimming.

8. The battery pack according to claim 7 , wherein the second inverter circuit comprises:

a second PMOS transistor whose gate is connected to an output terminal of e first inverter circuit;

a depression-type NMOS transistor whose gate and source are connected to the negative power source terminal of the charger;

at least one diode-connected PMOS transistor connected serially between a source of the second PMOS transistor nd the positive power source terminal of the charger; and

a trimming fuse connected between a source and a drain of each of the at least one diode-connected PMOS transistor,

wherein a junction node between drains of the second PMOS transistor and the depression-type NMOS transistor serves as an output terminal of the second inverter circuit.

9. The battery pack according to claim 1 , wherein the second inverter circuit comprises:

a second PMOS transistor whose gate is connected to an output terminal of the first inverter circuit;

at least one diode-connected PMOS transistor connected serially between a source of the second PMOS transistor and the positive power source terminal of the charger;

a trimming fuse connected between a source and a drain of each of the at least one diode-connected PMOS transistor;

a depression-type NMOS transistor whose gate is connected to the negative power source terminal of the charger;

at least resistor connected serially between a source of the depression-type NMOS transistor and the negative power source terminal of the charger; and

a trimming fuse connected in parallel to each of the t least one resistor,

wherein a junction node between drains of the second PMOS transistor and the depression-type NMOS transistor serves as an output terminal of the second inverter circuit.

10. The battery pack according to claim 1 , wherein the second inverter circuit comprises:

a second PMOS transistor whose gate is connected to an output terminal of the first inverter circuit;

at least one diode-connected PMOS transistor connected serially between a source of the second PMOS transistor and the positive power source terminal of the charger;

a trimming fuse connected between a source and a drain of each of the at least one diode-connected PMOS transistor;

a first depression-type NMOS transistor whose gate is connected to the negative power source terminal of the charger;

at least one second depression-type NMOS transistor whose gate and back gate are respectively connected to a source thereof and the negative voltage terminal of the charger, connected serially between a drain of the second PMOS transistor and a drain of the first depression-type NMOS transistor; and

a trimming fuse connected between a source and a drain of each of the at a one second depression-type NMOS transistor.

11. The battery pack according to claim 1 , wherein the second inverter circuit comprises:

a second PMOS transistor whose gate is connected to an output terminal of the first inverter circuit;

at least one diode-connected PMOS transistor connected serially between a source of the second PMOS transistor and the positive power source terminal of the charger;

a trimming fuse connected between a source and a drain of each of the at least one diode-connected PMOS transistor;

a first depression-type NMOS transistor whose gate, source, and back gate are connected to the negative power source terminal of the charger;

at least one second depression-type NMOS transistor whose gate and back gate are respectively connected to the negative voltage terminal of the charger and a source thereof, connected serially between a drain of the second PMOS transistor and a drain of the first depression-type NMOS transistor; and

a trimming fuse connected between a source and a drain al each of the at least one second depression-type NMOS transistor.

12. The battery pack according to claim 1 , wherein the second inverter circuit comprises:

a second PMOS transistor whose gate is connected to an output terminal of the first inverter circuit;

at least one diode-connected PMOS transistor connected serially between a source of the second PMOS transistor and the positive power source terminal of the charger;

a trimming fuse connected between a source and a drain of each of the at least one diode-connected PMOS transistor;

a first depression-type NMOS transistor whose gate, source, and back gate are connected to the negative power source terminal of the charger;

at least one second depression-type NMOS transistor whose gate and back gate are connected to the negative voltage terminal of the charger, connected serially between a drain of the second PMOS transistor and a drain of the first depression-type NMOS transistor; and

a trimming fuse connected between a source and a drain of each of the at least one second depression-type NMOS transistor.

13. The battery pack according to claim 1 , wherein an input threshold voltage of the first inverter circuit is variable by trimming a portion thereof as well as that of the second inverter circuit.

14. The battery pack according to claim 13 , wherein the input threshold voltage of the second, inverter circuit is raised by trimming a portion thereof.

15. The battery pack according to claim 13 , wherein the second inverter circuit comprises:

a second PMOS transistor whose gate and source are connected to an output terminal of the first inverter circuit and the positive power source terminal of the charger, respectively;

a depression-type NMOS transistor whose gale is connected to the negative power source terminal of the charger;

at least one resistor connected serially between a source of the depression-type NMOS transistor and the negative power source terminal of the charger; and

a trimming fuse connected in parallel to each of the at least one resistor,

wherein a junction node between drains of the second PMOS transistor and the depression-type NMOS transistor serves as an output terminal of the second inverter circuit.