Rapid discharge and reverse connection prevention protection circuit

Abstract

The utility model discloses a rapid discharge and reverse connection prevention protection circuit, which belongs to the field of integrated circuits and comprises a reverse connection protection circuit, a power failure detection circuit, a rapid discharge circuit, a driving circuit and a power supply circuit. The reverse connection protection circuit is composed of a metal oxide semiconductor field effect transistor (MOSFET) T1 and a bidirectional voltage-regulator tube ZD1. The power-off detection circuit is composed of a falling edge trigger circuit and a level conversion circuit. The rapid bleeder circuit is composed of a bleeder MOSFET (Metal Oxide Semiconductor Field Effect Transistor) T2 and a driver of the bleeder MOSFET T2; and the power supply circuit is connected with the level conversion circuit and the rapid bleeder circuit. According to the invention, repeated restart of the device caused by electrification of the output capacitor after switching off can be prevented, protection of the discharge tube QD when the charger is reversely connected can also be realized in a simplest mode, the reliability of the handheld device is improved, the repeated restart phenomenon during shutdown can also be prevented, and the user experience is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of integrated circuits, in particular to a fast discharge and anti-reverse connection protection circuit. Background Art

[0002] In personal laptops or handheld devices, the power supply mostly comes from lithium batteries. The characteristics of lithium batteries determine that the battery pack needs additional protection circuits and has very high requirements for the power consumption of the entire device after shutdown, so as to increase the battery standby time.

[0003] Currently, most solutions use AFE (Active Front End, rectifier / feedback unit) analog front end or fuel gauge to control the on / off of the current path to protect the battery and achieve low power consumption. However, there are also many pain points, especially the reverse connection protection of the charger and the residual voltage of the output capacitor. Figure 1 As shown, since the fuel gauge or AFE is powered by the battery, if the charger is reversely connected to the PACK+ terminal, the discharge tube will not shut off and a high negative voltage will appear on the PACK+ terminal. At this time, the discharge tube QD will discharge with a very large current, causing QD damage. Therefore, a separate circuit is required to prevent the charger from being reversely connected. In addition, the capacitor COUT at the output PACK+ terminal stores a high amount of energy. If the power is disconnected at this time, downstream devices (such as displays) will still flicker or turn on and off repeatedly due to the capacitor's charge, which is undesirable. Utility Model Content

[0004] The purpose of the utility model is to provide a fast discharge and anti-reverse connection protection circuit to solve the problems in the background technology.

[0005] In order to solve the above technical problems, the utility model provides a fast discharge and anti-reverse connection protection circuit, including a reverse connection protection circuit, a power failure detection circuit, a fast discharge circuit, a drive circuit and a power supply circuit;

[0006] The reverse connection protection circuit includes MOSFET1 and bidirectional voltage regulator ZD1. The two ends of the bidirectional voltage regulator ZD1 are connected to the gate and source of MOSFET1 respectively. The drain and source of MOSFET1 are connected to the gate and source of the discharge tube QD to be protected respectively as two output ends.

[0007] The power-off detection circuit includes a falling-edge trigger circuit and a level conversion circuit. The falling-edge trigger circuit detects the drive signal DRV_DIS from the front-end discharge tube QD. When the gate drive signal of the discharge tube QD falls, it indicates that the discharge tube QD is turned off and needs to be discharged quickly. The level conversion circuit converts the floating signal of the falling-edge trigger circuit into a ground-based signal.

[0008] The fast discharge circuit includes a discharge MOSFET2 and a driver for MOSFET2. The drive power of the discharge MOSFET2 comes from the power supply circuit. The drain end of MOSFET2 is directly connected to the positive terminal PACK+ of the external electrolytic capacitor as a terminal PACK+, or connected through an external resistor. When the drive signal DRV_DIS of the external discharge tube QD becomes low, the drive circuit drives MOSFET2 to turn on, and the electricity stored in the electrolytic capacitor is discharged to the ground through this path.

[0009] The power supply circuit is connected to the level conversion circuit and the fast discharge circuit to provide basic current capacity for the two.

[0010] In one embodiment, the MOSFET 2 is an N-type transistor with a low Vth threshold.

[0011] In one embodiment, a Vth threshold of the MOSFET2 of the fast discharge circuit is less than 2.7V.

[0012] The utility model provides a fast discharge and anti-reverse connection protection circuit, which can prevent the device from repeatedly restarting due to the output capacitor being charged after shutdown. It can also use the simplest method to realize the protection of the discharge tube QD when the charger is reversely connected. It not only improves the reliability of the handheld device, but also prevents the repeated restart phenomenon when shutting down, thereby improving the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of the current basic battery protection unit circuit structure.

[0014] Figure 2 It is a schematic diagram of the structure of the fast discharge circuit and the anti-reverse connection protection circuit provided by the present invention.

[0015] Figure 3 It is a schematic diagram of the overall circuit application structure of the present invention. DETAILED DESCRIPTION

[0016] The following is a detailed description of the rapid discharge and reverse polarity protection circuit proposed by the present invention, with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the accompanying drawings are highly simplified and not to exact scale, and are intended solely to facilitate and clearly illustrate the embodiments of the present invention.

[0017] The present invention provides a fast discharge and anti-reverse connection protection circuit, the structure of which is as follows: Figure 2 As shown, it includes a reverse connection protection circuit, a power failure detection circuit, a fast discharge circuit, a drive circuit and a power supply circuit.

[0018] like Figure 3The figure shows the overall application diagram of the present invention. The reverse connection protection circuit is composed of MOSFET1 and bidirectional voltage regulator ZD1. The two ends of the bidirectional voltage regulator ZD1 are respectively connected to the gate and source ends of MOSFET1 to protect MOSFET1; the drain and source ends of MOSFET1 are respectively connected to the two output ends of the chip of the present invention. Figure 1 The gate and source of the discharge tube QD that needs to be protected. When the charger is reversely connected, the reverse protection circuit will short-circuit the gate and source of the discharge tube QD, putting the discharge tube QD in a disconnected state to protect the discharge tube QD.

[0019] The power-off detection circuit consists of a falling-edge trigger circuit and a level conversion circuit. The falling-edge trigger circuit detects the discharge tube QD drive signal DRV_DIS from the front-end AFE. When the gate drive signal of the discharge tube QD drops, it indicates that the discharge tube QD is turned off. At this time, the output capacitor needs to be discharged quickly. The level conversion circuit converts the floating signal of the falling-edge trigger circuit (because the discharge tube QD is a high-side N-type MOSFET, its gate drive is floating) into a ground signal.

[0020] The fast discharge circuit consists of a discharge MOSFET2 and a driver for MOSFET2. The driving power of the discharge MOSFET2 comes from the power supply circuit, and MOSFET2 is an N-tube with a low Vth threshold, which can still work when the output capacitor voltage is low; the drain end of MOSFET2 is directly connected to the positive end PACK+ of the external electrolytic capacitor as a terminal PACK+ of the circuit of the present invention, or it can be connected through an external resistor. When the drive signal DRV_DIS of the external discharge tube QD becomes low, the drive circuit will drive MOSFET2 to open, and the electricity stored in the electrolytic capacitor will be discharged to the ground through this path.

[0021] The power supply circuit is connected to the level conversion circuit and the fast discharge circuit to provide basic current capacity for both. The power supply circuit comes from the output electrolytic capacitor, and its operating range is very wide, down to 2.7V. When the voltage of the electrolytic capacitor is higher than 2.7V, the circuit of the present invention can continue to work and discharge until the electrolytic voltage is lower than 2.7V. Therefore, the Vth threshold of MOSFET2 of the fast discharge circuit must also be less than 2.7V.

[0022] The above description is only a description of the preferred embodiment of the present invention and does not limit the scope of the present invention. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A fast discharge and anti-reverse connection protection circuit, characterized in that: Including reverse connection protection circuit, power failure detection circuit, fast discharge circuit, drive circuit and power supply circuit; The reverse connection protection circuit includes MOSFET1 and bidirectional voltage regulator ZD1. The two ends of the bidirectional voltage regulator ZD1 are connected to the gate and source of MOSFET1 respectively. The drain and source of MOSFET1 are connected to the gate and source of the discharge tube QD to be protected respectively as two output ends. The power-off detection circuit includes a falling-edge trigger circuit and a level conversion circuit. The falling-edge trigger circuit detects the drive signal DRV_DIS from the front-end discharge tube QD. When the gate drive signal of the discharge tube QD falls, it indicates that the discharge tube QD is turned off and needs to be discharged quickly. The level conversion circuit converts the floating signal of the falling-edge trigger circuit into a ground-based signal. The fast discharge circuit includes a discharge MOSFET2 and a driver for MOSFET2. The drive power of the discharge MOSFET2 comes from the power supply circuit. The drain end of MOSFET2 is directly connected to the positive terminal PACK+ of the external electrolytic capacitor as a terminal PACK+, or connected through an external resistor. When the drive signal DRV_DIS of the external discharge tube QD becomes low, the drive circuit drives MOSFET2 to turn on, and the electricity stored in the electrolytic capacitor is discharged to the ground through this path. The power supply circuit is connected to the level conversion circuit and the fast discharge circuit to provide basic current capacity for the two.

2. The fast discharge and anti-reverse connection protection circuit according to claim 1, characterized in that: The MOSFET 2 is an N-type transistor with a low Vth threshold.

3. The fast discharge and anti-reverse connection protection circuit according to claim 1, characterized in that: The Vth threshold of the MOSFET2 of the fast discharge circuit is less than 2.7V.

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