# US 10,312,702 B2 · Overvoltage and overcurrent protection circuit and mobile terminal

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- Number: US 10,312,702 B2
- Document ID: US10312702B2
- Status: Granted
- Kind: B2
- Application number: 15/114,207
- Filed: 2014-05-26
- Published: 2017-01-12
- Granted: 2019-06-04
- Earliest claimed: 2014-01-28
- Assignees: Guangdong Oppo Mobile Telecommunications Corp., Ltd.
- Applicants: Guang Dong Oppo Mobile Telecommunications Corp., Ltd.
- Inventors: Jialiang Zhang; Kewei Wu; Wenqiang Cheng; Dashuai Huang; Yuanxiang Hu
- Web page: https://patentgrep.com/patent/US10312702B2

## CPC

- H01M 10/44: Methods for charging or discharging (circuits for charging H02J7/00)
- H01M 10/448: {End of discharge regulating measures}
- H01M 50/572: Means for preventing undesired use or discharge
- H01M 50/583: in response to current, e.g. fuses
- H02H 7/18: for batteries; for accumulators
- H02J 7/62: against overcurrent
- H02J 7/64: against overvoltage
- H02J 7/865: {Battery or charger load switching, e.g. concurrent charging and load supply (H02J7/50 takes precedence)}
- H01H 2085/025: {Structural association with a binding post of a storage battery}
- H01H 2085/0283: {Structural association with a semiconductor device}
- H01M 2200/00: Safety devices for primary or secondary batteries
- H01M 2200/103: Fuse
- H01M 2220/30: Batteries in portable systems, e.g. mobile phone, laptop
- H02H 3/087: for DC applications
- H02H 3/202: {for DC systems}
- H02J 7/61: against overcharge
- H02J 7/63: against overdischarge
- H02J 2207/10: Control circuit supply, e.g. means for supplying power to the control circuit
- Y02E 60/10: Energy storage using batteries
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H)
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

The present disclosure provides an overvoltage and overcurrent protection circuit and a mobile terminal. The overvoltage and overcurrent protection circuit comprises a primary protection circuit and a secondary protection circuit. The primary protection circuit comprises a power end coupled to an anode of a cell, a detection end coupled to a cathode of the cell, and a low potential interface end coupled to a ground end of a charging and discharging interface. The secondary protection circuit comprises a high potential cell end, a low potential cell end, and a high potential interface end, in which the high potential cell end is externally coupled to the anode of the cell, the low potential cell end is externally coupled to the cathode of the cell, and the high potential interface end is externally coupled to a power end of the charging and discharging interface.

## Claims

### Claim 1

An overvoltage and overcurrent protection circuit, comprising:
a primary protection circuit, comprising a power end, a detection end, and a low potential interface end, wherein the power end is coupled to an anode of a cell, the detection end is coupled to a cathode of the cell, and the low potential interface end is coupled to a ground end of a charging and discharging interface; the primary protection circuit is configured to detect whether there is an over-charging when the cell is charged, and to switch off charging the cell via the charging and discharging interface if there is the over-charging; the primary protection circuit is further configured to detect whether there is an over-discharging when the cell is discharging, and switch off discharging of the cell via the charging and discharging interface if there is the over-discharging; and
a secondary protection circuit, comprising a high potential cell end, a low potential cell end, and a high potential interface end, wherein the high potential cell end is externally coupled to the anode of the cell, the low potential cell end is externally coupled to the cathode of the cell, and the high potential interface end is externally coupled to a power end of the charging and discharging interface; the secondary protection circuit is configured to perform an overvoltage protection and an overcurrent protection via a fuse when the cell is charged via the charging and discharging interface.

### Claim 2 (depends on 1)

The overvoltage and overcurrent protection circuit according to claim 1, wherein, the overvoltage and overcurrent protection circuit further comprises:
a filtering circuit, comprising a high potential end and a low potential end; wherein, the high potential end is coupled to the low potential interface end of the primary protection circuit, and the low potential end is coupled to the high potential interface end of the secondary protection circuit; the filtering circuit is configured to perform a low-pass filtering on an electric signal inputted from the charging and discharging interface when the cell is charged via the charging and discharging interface.

### Claim 3 (depends on 1)

The overvoltage and overcurrent protection circuit according to claim 1, wherein,
the secondary protection circuit comprises a first resistor, a first capacitor, a second resistor, a second capacitor, a third resistor, a third capacitor, a voltage detection chip, a limit-voltage and limit-current fuse chip and a switch circuit;
a first terminal of the first resistor, a second terminal of third resistor and a second fuse pin of the limit-voltage and limit-current fuse chip are respectively configured as the high potential cell end, the low potential cell end and the high potential interface end of the secondary protection circuit, a positive voltage detection pin, a negative voltage pin, a control output pin, a power pin and a delay pin of the voltage detection chip are respectively coupled to a second terminal of the first resistor, a first terminal of the first capacitor, a second terminal of the third resistor, a controlled terminal of the switch circuit, a first terminal of the third capacitor and a first terminal of the second capacitor, each of a second terminal of the first capacitor, a second terminal of the third capacitor and a second terminal of the second capacitor is coupled to a second terminal of the third resistor, a first terminal and a second terminal of the second resistor are respectively coupled to a first fuse pin of the limit-voltage and limit-current fuse chip and the first terminal of the third capacitor, a first terminal of the third resistor is coupled to a control end of the switch circuit, a high potential end and a low potential end of the switch circuit are respectively coupled to a limit-voltage pin of the limit-voltage and limit-current fuse chip and a second terminal of the third resistor.

### Claim 4 (depends on 3)

The overvoltage and overcurrent protection circuit according to claim 3, wherein,
the switch circuit comprises a NMOS transistor; and
a drain electrode, a gate electrode and a source electrode of the NMOS transistor are respectively configured as the high potential end, the controlled end and the low potential end of the switch circuit.

### Claim 5 (depends on 1)

The overvoltage and overcurrent protection circuit according to claim 1, wherein,
the primary protection circuit comprises a fourth resistor, a fifth resistor, a sixth resistor, a fourth capacitor, a fifth capacitor, a sixth capacitor, an over-charging and over-discharging detecting chip, a third switch chip and a fourth switch chip;
a first terminal of the fourth resistor, a first terminal of the fifth resistor and a second terminal of the sixth resistor are respectively configured as the power end, the detection end and the low potential interface end of the primary protection circuit; a current detection pin, a power pin, a ground pin, a low potential pin, an over-charging pin and an over-discharging pin of the over-charging and over-discharging detecting chip are respectively coupled to a second terminal of the fourth resistor, a first terminal of the fourth capacitor, a first terminal of the fifth resistor, a first terminal of the sixth resistor, a first gate pin of the third switch chip and a second gate pin of the third switch chip, a second terminal of the fourth capacitor is coupled to a first terminal of the fifth resistor, a first source pin and a second source pin of the third switch chip are respectively grounded and coupled to a second terminal of the fifth resistor, a third gate pin, a fourth gate pin, a third source pin, and a fourth source pin of the fourth switch chip are respectively coupled to the first gate pin, the second gate pin, the first source pin, and the second source pin of the third switch chip, the fifth capacitor and the sixth capacitor coupled in series are coupled between the first source pin and the second source pin of the third switch chip, and a second terminal of the sixth resistor is grounded.

### Claim 6 (depends on 2)

The overvoltage and overcurrent protection circuit according to claim 2, wherein,
the filtering circuit comprises a seventh capacitor and an eighth capacitor; and
a first terminal of the seventh capacitor and a second terminal of the eighth capacitor are respectively configured as the high potential end and the low potential end of the filtering circuit, and a second terminal of the seventh capacitor is coupled to a first terminal of the eighth capacitor.

### Claim 7 (depends on 1)

The overvoltage and overcurrent protection circuit according to claim 1, wherein, the charging and discharging interface is a USB (Universal Serial Bus) interface.

### Claim 8 (depends on 7)

The overvoltage and overcurrent protection circuit according to claim 7, wherein, a power end and a ground end of the USB interface can support current equal to or less than a preset current threshold.

### Claim 9 (depends on 8)

The overvoltage and overcurrent protection circuit according to claim 8, wherein,
the power end of the USB interface comprises at least two power pins; and
the ground end of the USB interface comprises at least two ground pins.

### Claim 10

A mobile terminal, comprising a cell and a charging and discharging interface, wherein, the mobile terminal further comprises the overvoltage and overcurrent protection circuit, and the overvoltage and overcurrent protection circuit comprises:
a primary protection circuit, comprising a power end, a detection end, and a low potential interface end, wherein the power end is coupled to an anode of a cell, the detection end is coupled to a cathode of the cell, and the low potential interface end is coupled to a ground end of a charging and discharging interface; the primary protection circuit is configured to detect whether there is an over-charging when the cell is charged, and to switch off charging the cell via the charging and discharging interface if there is the over-charging; the primary protection circuit is further configured to detect whether there is an over-discharging when the cell is discharging, and switch off discharging of the cell via the charging and discharging interface if there is the over-discharging; and
a secondary protection circuit, comprising a high potential cell end, a low potential cell end, and a high potential interface end, wherein the high potential cell end is externally coupled to the anode of the cell, the low potential cell end is externally coupled to the cathode of the cell, and the high potential interface end is externally coupled to a power end of the charging and discharging interface; the secondary protection circuit is configured to perform an overvoltage protection and an overcurrent protection via a fuse when the cell is charged via the charging and discharging interface.

### Claim 11 (depends on 3)

The overvoltage and overcurrent protection circuit according to claim 3, wherein,
the limit-voltage and limit-current fuse chip comprises a first fuse, a second fuse and a seventh resistor;
the first fuse and the second fuse are coupled in series and coupled between the first fuse pin and the second fuse pin of the limit-voltage and limit-current fuse chip; and
the seventh resistor is coupled between a junction of the first fuse and the second fuse and the limit-voltage pin of the limit-voltage and limit-current fuse chip.

### Claim 12 (depends on 9)

The overvoltage and overcurrent protection circuit according to claim 9, wherein a number of the power pins is equal to that of the ground pins.

### Claim 13 (depends on 8)

The overvoltage and overcurrent protection circuit according to claim 8, wherein the preset current threshold is 4 A.

### Claim 14 (depends on 10)

The mobile terminal according to claim 10, wherein the overvoltage and overcurrent protection circuit further comprises:
a filtering circuit, comprising a high potential end and a low potential end; wherein, the high potential end is coupled to the low potential interface end of the primary protection circuit, and the low potential end is coupled to the high potential interface end of the secondary protection circuit; the filtering circuit is configured to perform a low-pass filtering on an electric signal inputted from the charging and discharging interface when the cell is charged via the charging and discharging interface.

### Claim 15 (depends on 10)

The mobile terminal according to claim 10, wherein,
the secondary protection circuit comprises a first resistor, a first capacitor, a second resistor, a second capacitor, a third resistor, a third capacitor, a voltage detection chip, a limit-voltage and limit-current fuse chip and a switch circuit;
a first terminal of the first resistor, a second terminal of third resistor and a second fuse pin of the limit-voltage and limit-current fuse chip are respectively configured as the high potential cell end, the low potential cell end and the high potential interface end of the secondary protection circuit, a positive voltage detection pin, a negative voltage pin, a control output pin, a power pin and a delay pin of the voltage detection chip are respectively coupled to a second terminal of the first resistor, a first terminal of the first capacitor, a second terminal of the third resistor, a controlled terminal of the switch circuit, a first terminal of the third capacitor and a first terminal of the second capacitor, each of a second terminal of the first capacitor, a second terminal of the third capacitor and a second terminal of the second capacitor is coupled to a second terminal of the third resistor, a first terminal and a second terminal of the second resistor are respectively coupled to a first fuse pin of the limit-voltage and limit-current fuse chip and the first terminal of the third capacitor, a first terminal of the third resistor is coupled to a control end of the switch circuit, a high potential end and a low potential end of the switch circuit are respectively coupled to a limit-voltage pin of the limit-voltage and limit-current fuse chip and a second terminal of the third resistor.

### Claim 16 (depends on 15)

The mobile terminal according to claim 15, wherein,
the switch circuit comprises a NMOS transistor; and
a drain electrode, a gate electrode and a source electrode of the NMOS transistor are respectively configured as the high potential end, the controlled end and the low potential end of the switch circuit.

### Claim 17 (depends on 10)

The mobile terminal according to claim 10, wherein the charging and discharging interface is a USB interface.

### Claim 18

An overvoltage and overcurrent protection method, comprising:
when a cell is charged, detecting by a primary protection circuit and a secondary protection circuit, a charging voltage and a charging current in real time;
if a switch-off condition is satisfied, performing at least one act of: switching off a charging loop for charging the cell by the primary protection circuit through controlling a MOS transistor and switching off the charging loop by the secondary protection circuit through switching off a fuse, wherein the switch-off condition comprises at least one of: the charging voltage being greater than a preset voltage threshold, the charging current being greater than a first preset current threshold, and the cell being fully charged.

### Claim 19 (depends on 18)

The overvoltage and overcurrent protection method according to claim 18, further comprising:
when the cell is discharging, detecting by the primary protection circuit a discharging current of the cell through a resistor, and detecting by the second protection circuit the discharging current of the cell through the fuse;
if the discharging current is greater than a second preset current threshold, switching off a discharging loop by the primary protection circuit through controlling the MOS transistor; and/or switching off the discharging loop by the secondary protection circuit through switching off the fuse.

### Claim 20 (depends on 18)

The overvoltage and overcurrent protection method according to claim 18, further comprising:
performing a low-pass filtering on a power signal before the power signal is used to charge the cell.