Systems and methods for overcurrent detection of charge pumps

1 . An overcurrent detector for a charging path of a charge pump, the charging path including a switch associated with a switch on-resistance value, the charge pump being configured to receive an input voltage and generate an output voltage to charge a battery, the overcurrent detector comprising:

a reference unit biased to the output voltage and configured to generate a reference voltage representing a predetermined threshold current for the switch of the charging path;

a detection unit coupled to the reference unit and configured to generate a sensing voltage representing a charging current that flows through the switch of the charging path; and

an output unit configured to generate an over-current-protection signal based at least in part on the reference voltage and the sensing voltage;

wherein the output unit is further configured to, in response to the sensing voltage exceeding the reference voltage, generate the over-current-protection signal that indicates the charging current exceeds the predetermined threshold current;

wherein the reference unit includes:

a first current source configured to generate a first reference current; and

a first transistor associated with a first on-resistance value.

2 . The overcurrent detector of claim 1 wherein:

the first reference current is equal to the predetermined threshold current divided by a predetermined constant; and

the first on-resistance value is equal to the switch on-resistance value multiplied by the predetermined constant.

3 . The overcurrent detector of claim 1 wherein the detection unit includes a second current source configured to generate a second reference current that is equal to the first reference current in magnitude.

4 . The overcurrent detector of claim 3 wherein:

the reference unit includes a second transistor associated with a second on-resistance value; and

the detection unit includes a third transistor associated with a third on-resistance value;

wherein:

the second transistor and the third transistor are coupled to each other; and

the second on-resistance value and the third on-resistance value are equal.

5 . The overcurrent detector of claim 4 wherein the output unit includes a third current source configured to generate a third reference current that is equal to the first reference current in magnitude.

6 . The overcurrent detector of claim 5 wherein the output unit further includes:

a fourth transistor connected to the third current source;

a NOT gate connected to the third current source and the fourth transistor and configured to generate a first logic signal; and

an AND gate configured to receive the first logic signal and a second logic signal and generate the over-current-protection signal.

7 . The overcurrent detector of claim 6 wherein:

the first transistor of the reference unit is configured to receive a drive signal; and

the drive signal and the second logic signal are the same.

8 . The overcurrent detector of claim 6 wherein:

the detection unit includes a fifth transistor connected to the third transistor and configured to receive a drive signal; and

the drive signal and the second logic signal are the same.

9 . An overcurrent detector for a charging path of a charge pump, the charging path including a switch associated with a switch on-resistance value, the charge pump being configured to receive an input voltage and generate an output voltage to charge a battery, the overcurrent detector comprising:

a reference unit biased to the output voltage and configured to generate a reference voltage representing a predetermined threshold current for the switch of the charging path;

a detection unit coupled to the reference unit and configured to generate a sensing voltage representing a charging current that flows through the switch of the charging path; and

an output unit configured to generate an over-current-protection signal based at least in part on the reference voltage and the sensing voltage;

wherein the output unit is further configured to, in response to the sensing voltage exceeding the reference voltage, generate the over-current-protection signal that indicates the charging current exceeds the predetermined threshold current;

wherein the overcurrent detector is configured to periodically perform overcurrent detection for the charging path of the charge pump;

wherein the overcurrent detector is further configured to:

perform the overcurrent detection for the charging path of the charge pump during a first charging duration of each period of a periodic clock signal; and

not perform the overcurrent detection for the charging path of the charge pump during a second charging duration of the each period of the periodic clock signal;

wherein the each period of the periodic clock signal includes the first charging duration and the second charging duration.

10 . The overcurrent detector of claim 9 , and further comprising a current holding unit configured to allow a reference current to flow from at least a part of the reference unit through the current holding unit during the second charging duration of the each period of the periodic clock signal.

11 . An overcurrent detector for a charging path of a charge pump, the charging path including a switch associated with a switch on-resistance value, the charge pump being configured to receive an input voltage and generate an output voltage to charge a battery, the overcurrent detector comprising:

a reference unit biased to the output voltage and configured to generate a reference voltage representing a predetermined threshold current for the switch of the charging path;

a detection unit coupled to the reference unit and configured to generate a sensing voltage representing a charging current that flows through the switch of the charging path; and

an output unit configured to generate an over-current-protection signal based at least in part on the reference voltage and the sensing voltage;

wherein the output unit is further configured to, in response to the sensing voltage exceeding the reference voltage, generate the over-current-protection signal that indicates the charging current exceeds the predetermined threshold current;

wherein the overcurrent detector is configured to periodically perform overcurrent detection for the charging path of the charge pump;

wherein the overcurrent detector is further configured to:

not perform the overcurrent detection for the charging path of the charge pump during a first charging duration of each period of a periodic clock signal; and

perform the overcurrent detection for the charging path of the charge pump during a second charging duration of the each period of the periodic clock signal;

wherein the each period of the periodic clock signal includes the first charging duration and the second charging duration.

12 . The overcurrent detector of claim 11 , and further comprising a current holding unit configured to allow a reference current to flow from at least a part of the detection unit through the current holding unit during the first charging duration of the each period of the periodic clock signal.

13 . An overcurrent detection method for a charging path of a charge pump, the charging path including a switch associated with a switch on-resistance value, the charge pump being configured to receive an input voltage and generate an output voltage to charge a battery, the overcurrent detection method comprising:

generating a reference voltage representing a predetermined threshold current for the switch of the charging path based at least in part on the output voltage;

generating a sensing voltage representing a charging current that flows through the switch of the charging path;

processing information associated with the reference voltage and the sensing voltage;

generating an over-current-protection signal based at least in part on the reference voltage and the sensing voltage; and

performing overcurrent detection for the charging path of the charge pump during each period of a periodic clock signal;

wherein the generating an over-current-protection signal based at least in part on the reference voltage and the sensing voltage includes:

in response to the sensing voltage exceeding the reference voltage, generating the over-current-protection signal that indicates the charging current exceeds the predetermined threshold current;

wherein the each period of the periodic clock signal includes the first charging duration and the second charging duration.

14 . The overcurrent detection method of claim 13 wherein the performing overcurrent detection for the charging path of the charge pump during each period of a periodic clock signal includes:

performing the overcurrent detection for the charging path of the charge pump during the first charging duration of the each period of the periodic clock signal; and

not performing the overcurrent detection for the charging path of the charge pump during the second charging duration of the each period of the periodic clock signal.

15 . The overcurrent detection method of claim 13 wherein the performing overcurrent detection for the charging path of the charge pump during each period of a periodic clock signal includes:

not performing the overcurrent detection for the charging path of the charge pump during the first charging duration of the each period of the periodic clock signal; and

performing the overcurrent detection for the charging path of the charge pump during the second charging duration of the each period of the periodic clock signal.