Overcurrent protection circuit and method for limiting discharge current of battery within safety limiting value

Patent metadata

Field	Value
Publication number	US-10090689-B2
Application number	US-201315103930-A
Country	US
Kind code	B2
Filing date	Dec 13, 2013
Priority date	Dec 13, 2013
Publication date	Oct 2, 2018
Grant date	Oct 2, 2018

Abstract

An overcurrent protection circuit and method for battery discharge. The overcurrent protection circuit includes a discharge switch tube; a discharge control module which is used for detecting the discharge current of batteries in real time, and judging whether an overcurrent is generated by way of comparing the detected discharge current with a preset limiting value, the discharge control module controlling switch-on of the discharge switch tube if no overcurrent is generated, the discharge control module controlling switch-off of the discharge switch tube if an overcurrent is generated, and the discharge control module locking the discharge switch tube in a switch-off state when the overcurrent has timed out; and a time delay module which is used for judging whether the overcurrent has timed out by way of comparing the time when the overcurrent is generated with a preset delay time.

First claim

What is claimed is:

1. An overcurrent protection circuit for battery discharge, comprising: a discharge switch transistor connected in a battery discharge path, wherein the overcurrent protection circuit further comprises:
a discharge control module configured to detect a discharge current of a battery in real time, and determine whether an overcurrent occurs by comparing the detected discharge current with a preset limiting value, wherein if no overcurrent occurs, the discharge control module controls the discharge switch transistor to be switched on; and if the overcurrent occurs, the discharge control module controls the discharge switch transistor to operate in a manner of being switched-on discontinuously, and when the overcurrent has timed out, the discharge control module locks the discharge switch transistor in the switch-off state; and
a time delay module configured to determine whether the overcurrent has timed out by comparing the time of the overcurrent with a preset delay time.

2. The overcurrent protection circuit for battery discharge of claim 1 , wherein the discharge control module comprises a battery protection chip, a sampling resistor, a comparator, and a current limit control switch transistor, a first terminal of the sampling resistor is connected to a negative electrode of the battery and a ground, a second terminal of the sampling resistor is connected to a second terminal of the discharge switch transistor and a first input terminal of the comparator, a first terminal of the discharge switch transistor is connected to a negative electrode of a discharge port, a second input terminal of the comparator is connected to a reference voltage, an output terminal of the comparator is connected to a control terminal of the current limit control switch transistor, a second terminal of the current limit control switch transistor is connected to the ground, and a first terminal of the current limit control switch transistor is connected to a control terminal of the discharge switch transistor and a discharge control terminal of the battery protection chip.

3. The overcurrent protection circuit for battery discharge of claim 2 , wherein the discharge control module further comprises a current limit resistor, a first terminal of the current limit resistor is connected to the discharge control terminal of the battery protection chip, and a second terminal of the current limit resistor is connected to the control terminal of the discharge switch transistor and the first terminal of the current limit control switch transistor.

4. The overcurrent protection circuit for battery discharge of claim 2 , wherein the time delay module comprises a first diode, a first switch transistor, a second switch transistor, a first capacitor, a first resistor, a second resistor, a third resistor and a fourth resistor, a first terminal of the first switch transistor is connected to a voltage sampling terminal of the battery protection chip, a second terminal of the first switch transistor and a second terminal of the second switch transistor are connected to the ground, a control terminal of the first switch transistor and a first terminal of the second switch transistor are connected to the negative electrode of the discharge port via the first resistor, a positive electrode of the first diode is connected to the negative electrode of the discharge port, a negative electrode of the first diode is connected to a first terminal of the first capacitor and a control terminal of the second switch transistor via the second resistor, a second terminal of the first capacitor is connected to the ground, the negative electrode of the discharge port is further connected to the voltage sampling terminal of the battery protection chip via the third resistor, and the fourth resistor is connected between the negative electrode of the first diode and the ground.

5. The overcurrent protection circuit for battery discharge of claim 1 , wherein the discharge control module comprises a battery protection chip, a sampling resistor, a comparator, an amplifier, and a current limit control switch transistor, a first terminal of the sampling resistor is connected to a positive electrode of the battery and a first input terminal of the amplifier, a second terminal of the sampling resistor is connected to a positive electrode of a discharge port and a second input terminal of the amplifier, an output terminal of the amplifier is connected to a first input terminal of the comparator, a second input terminal of the comparator is connected to a reference voltage, an output terminal of the comparator is connected to a control terminal of the current limit control switch transistor, a second terminal of the current limit control switch transistor is connected to the ground, a first terminal of the current limit control switch transistor is connected to a control terminal of the discharge switch transistor and a discharge control terminal of the battery protection chip, a first terminal of the discharge switch transistor is connected to a negative electrode of the discharge port, and a second terminal of the discharge switch transistor is connected to a negative electrode of the battery and the ground.

6. The overcurrent protection circuit for battery discharge of claim 5 , wherein the discharge control module further comprises a current limit resistor, a first terminal of the current limit resistor is connected to the discharge control terminal of the battery protection chip, and a second terminal of the current limit resistor is connected to the control terminal of the discharge switch transistor and the first terminal of the current limit control switch transistor.

7. The overcurrent protection circuit for battery discharge of claim 5 , wherein the time delay module comprises a first diode, a first switch transistor, a second switch transistor, a first capacitor, a first resistor, a second resistor, a third resistor and a fourth resistor, a first terminal of the first switch transistor is connected to a voltage sampling terminal of the battery protection chip, a second terminal of the first switch transistor and a second terminal of the second switch transistor are connected to the ground, a control terminal of the first switch transistor and a first terminal of the second switch transistor are connected to the negative electrode of the discharge port via the first resistor, a positive electrode of the first diode is connected to the negative electrode of the discharge port, a negative electrode of the first diode is connected to a first terminal of the first capacitor and a control terminal of the second switch transistor via the second resistor, a second terminal of the first capacitor is connected to the ground, the negative electrode of the discharge port is further connected to the voltage sampling terminal of the battery protection chip via the third resistor, and the fourth resistor is connected between the negative electrode of the first diode and the ground.

8. The overcurrent protection circuit for battery discharge of claim 1 , wherein the discharge control module comprises a battery protection chip, a sampling resistor, a current limit control switch transistor, a fifth resistor, a sixth resistor, a second capacitor and a second diode, a first terminal of the sampling resistor is connected to a negative electrode of the battery and a ground, a second terminal of the sampling resistor is connected to a second terminal of the discharge switch transistor and a second terminal of the current limit control switch transistor, a first terminal of the discharge switch transistor is connected to a negative electrode of a discharge port, a control terminal of the discharge switch transistor is connected to a positive elect

Assignees

• Hytera Comm Corp Ltd

Inventors

• Pan Qihui
• Lu Liangfei
• Yu Kok Hoong
• Xiong Yunyuan

Classifications

• H02J7/96

  in response to battery voltage · CPC title

• H02J7/63

  against overdischarge · CPC title

• H02J7/663

  using battery or load disconnect circuits (H02J9/002 takes precedence) · CPC title

• H02J7/94

  in response to battery current · CPC title

• H02J7/62

  against overcurrent · CPC title