A circuit and method based on temperature detection and protection of MOS transistor on-resistance

Abstract

The application relates to the technical field of lithium batteries, in particular to a circuit based on MOS tube conduction resistance temperature detection and protection. The circuit comprises a battery and main power circuit, a linear voltage stabilizing power supply circuit, a MOS drain-source voltage detection circuit, a current sampling detection circuit, an over-temperature comparison circuit, a proportional mapping circuit and a protection execution circuit. The B+ port of the battery and main power circuit is connected with the VIN port of the linear voltage stabilizing power supply circuit; the B- port of the battery and main power circuit is respectively connected with the GND port of the linear voltage stabilizing power supply circuit, the GND port of the MOS drain-source voltage detection circuit and the GND port of the current sampling detection circuit. Compared with the prior art, the circuit reduces the complexity of peripheral devices and wiring, reduces the system cost, effectively avoids the problem of protection failure caused by program abnormality, introduces a fuse or latch structure, avoids the risk caused by repeated triggering of traditional recoverable protection, and significantly improves the system safety level.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, specifically a circuit and method for detecting and protecting the on-resistance temperature of a MOSFET. Background Technology

[0002] In existing lithium battery systems, temperature protection mainly relies on NTC thermistors for detection. This method has the following problems: NTCs are usually located in the cell or PCB, and cannot accurately reflect the junction temperature of the power MOSFET. As the main charging and discharging path device, the MOSFET generates concentrated heat due to its conduction loss, resulting in a rapid temperature rise. In contrast, NTCs suffer from thermal conduction delay, leading to detection lag. Existing battery management chips (such as the BQ series) can only provide battery temperature protection and cannot monitor the temperature of the MOSFET itself. Most existing over-temperature protection mechanisms are recoverable, automatically resuming conduction after the temperature drops, which carries the risk of repeated triggering. When the battery management chip malfunctions or fails, the system may completely lose its temperature protection capability. The lack of a hardware-level safety protection mechanism independent of the main control system makes it difficult to meet the safety requirements of medical devices. Summary of the Invention

[0003] To address the problems mentioned in the background art, this invention provides a circuit for MOSFET on-resistance temperature detection and protection, including a battery and main power circuit, a linear voltage regulator circuit, a MOSFET drain-source voltage detection circuit, a current sampling detection circuit, an over-temperature comparator circuit, a proportional mapping circuit, and a protection execution circuit. The B+ port of the battery and main power circuit is connected to the VIN port of the linear voltage regulator circuit. The B- port of the battery and main power circuit is connected to the GND port of the linear voltage regulator circuit, the GND port of the MOSFET drain-source voltage detection circuit, and the GND port of the current sampling detection circuit, respectively. The 5V port of the linear voltage regulator circuit is connected to the 5V ports of the MOSFET drain-source voltage detection circuit, the current sampling detection circuit, the proportional mapping circuit, and the over-temperature comparator circuit, respectively. The VR_11 port of the battery and main power circuit is connected to the VR_11 port of the current sampling detection circuit. The VR_12 port of the battery and main power circuit is connected to the VR_12 port of the current sampling detection circuit. The Q3_D port of the MOSFET in the battery and main power circuit is connected to the MOSFET... The MOSFET Q3_D port of the drain-source voltage detection circuit and the MOSFET Q3_S port of the battery and main power circuit are connected to the MOSFET Q3_S port of the drain-source voltage detection circuit. The FUSE port of the battery and main power circuit are connected to the F2_Ctr-A port of the protection execution circuit and the TH port of the over-temperature comparator circuit, respectively. The Vds port of the over-temperature comparator circuit is connected to the Vds port of the drain-source voltage detection circuit. The Vk port of the over-temperature comparator circuit is connected to the Vk port of the proportional mapping circuit. The Vi port of the proportional mapping circuit is connected to the Vi port of the current sampling detection circuit.

[0004] The battery and main power circuit includes a 5-pin socket (5PIN), chip U1, and chip U2. The PBI pin of chip U1 is connected to one end of capacitor C8, and the other end of capacitor C8 is grounded. The VC4 pin of chip U1 is connected to one end of capacitor C15 and one end of resistor R20, with the other end of resistor R20 connected to the B+ port. The VC3 pin of chip U1 is connected to the other end of capacitor C15, one end of capacitor C16, and one end of resistor R21, with the other end of resistor R21 connected to the BT3 port. The VC2 pin of chip U1 is connected to the other end of capacitor C16, one end of capacitor C17, and one end of resistor R22, with the other end of resistor R22 connected to the BT2 port. The VC1 pin of chip U1 is connected to capacitor C15, one end of capacitor C16, one end of capacitor C17, and one end of resistor R22, with the other end of resistor R22 connected to the BT2 port. The other end of C17, one end of capacitor C18, and one end of resistor R23 are connected. The other end of resistor R23 is connected to the BT1 port. The other end of capacitor C18 is grounded. The SRN pin of chip U1 is connected to one end of capacitor C11, one end of capacitor C14, and one end of resistor R24. The other end of capacitor C14 is grounded. The NC pin and VSS pin of chip U1 are grounded together. The SRP pin of chip U1 is connected to the other end of capacitor C11, one end of capacitor C13, and one end of resistor R31. The other end of resistor R31 is connected to one end of resistor R25 (B-port). The TS1 pin of chip U1 is connected to one end of resistor RT2. The #PRES / #SHUTDN pins of chip U1 are connected to... One end of resistor R16, the other end of resistor RT2, the other end of resistor R16, the TS2 pin, TS3 pin, and TS4 pin of chip U1 are connected to ground. The #DISP pin of chip U1 is connected to one end of resistor R12. The other end of resistor R12 is connected to one end of capacitor C6 and one end of switch S1. The other end of capacitor C6 and the other end of switch S1 are connected to ground. The SMBD pin of chip U1 is connected to one end of resistor R8. The other end of resistor R8 is connected to one end of resistor R4, one end of resistor R1, and one end of diode D2. The other end of resistor R1 is connected to the SDA port. The SMBC pin of chip U1 is connected to one end of resistor R7. The other end of resistor R7 is connected to... Connect one end of resistor R6, one end of resistor R2, and one end of diode D2. Connect the other end of resistor R2 to the SCK port. Connect the other ends of resistors R24, R25, R4, R6, and diode D2, along with one end of capacitor C2, to the P- port and ground respectively. Connect the LEDCNTLA pin of chip U1 to the cathode of diode D4 and the anode of diode D1. Connect the LEDCNTLB pin of chip U1 to the anodes of diodes D4, D5, D6, and D1 respectively. Connect the LEDCNTLC pin of chip U1 to the cathode of diode D5 and the anode of diode D6 respectively.The PTC pin of chip U1 is connected to one end of resistor RTC1 and one end of capacitor C5. The PTCEN pin of chip U1 is connected to the other end of resistor RTC1, the other end of capacitor C5, and the B+ port. The VCC pin of chip U1 is connected to one end of resistor R11. The PACK pin of chip U1 is connected to one end of resistor R3. The DSG pin of chip U1 is connected to one end of resistor R10. The PCHG pin of chip U1 is connected to one end of resistor R14. The CHG pin of chip U1 is connected to one end of resistor R13. The BAT pin of chip U1 is connected to one end of diode D7. The source of MOSFET Q3 is connected to one end of resistor R15, one end of capacitor C4, one end of protector F1, and the S port of MOSFET Q3. The gate of MOSFET Q3 is connected to the other ends of resistors R13 and R15. One end of protector F1 is connected to the cathodes of diodes D10 and D11. The anode of diode D10 is connected to the TH interface, and the anode of diode D11 is connected to the F2_Ctr-A interface. The other ends of protector F1, diode D7, and resistor R20 are combined and connected to the B+ port. The drain of MOSFET Q3 is connected to the Q3_D port, the other end of resistor R14, and the other end of resistor R11. The drain of MOSFET Q2 and the source of MOSFET Q2 are connected to one end of resistor R9, the source of MOSFET Q1, one end of capacitor C3, one end of resistor R36, and diode D3. One end of the resistor R1 is connected to the VR_11 port. The other end of capacitor C3 is connected to the other end of capacitor C4. The gate of MOSFET Q2 is connected to the other end of resistor R9, the other end of resistor R10, and the drain of MOSFET Q1. The gate of MOSFET Q1 is connected to the other end of diode D3 and one end of resistor R5. The other end of resistor R5 is grounded. The other end of resistor R36 is connected to the other end of resistor R3, one end of capacitor C1, the VR_12 port, and the P+ port. The other end of capacitor C1 is connected to the other end of capacitor C2. Pin 1 of the 5-pin socket is connected to the P+ port. Pin 2 of the 5-pin socket is connected to the SCK port. Pin 3 of the 5-pin socket is connected to the SDA port. Pin 4 of the chip is connected to one end of resistor RT1 and the TS1 port, respectively. The other end of resistor RT1 is connected to the P- port. Pin 5 of the 5-pin socket is connected to the P- port. The VCC pin of chip U2 is connected to one end of capacitor C12 and one end of resistor R26, respectively. The other end of capacitor C12 is grounded, and the other end of resistor R26 is connected to the B+ port. The ICT pin of chip U2 is connected to one end of capacitor C9, and the other end of capacitor C9 is connected to one end of capacitor C10, the other end of capacitor C10 is grounded. The CO pin of chip U2 is connected to one end of resistor R18, and the other end of resistor R18 is connected to the Q3_G port of MOSFET. The SENSE pin of chip U2 is connected to one end of resistor R27 and one end of capacitor C19, respectively.The other end of resistor R27 is connected to the B+ port. The VC1 pin of chip U2 is connected to the other end of capacitor C19, one end of resistor R28, and one end of capacitor C20. The other end of resistor R28 is connected to the BT3 port. The VC2 pin of chip U2 is connected to the other end of capacitor C20, one end of resistor R29, and one end of capacitor C21. The other end of resistor R29 is connected to the BT2 port. The VC3 pin of chip U2 is connected to the other end of capacitor C21, one end of resistor R30, and one end of capacitor C22. The other end of resistor R30 is connected to the BT1 port. The VSS pin of chip U2 is connected to the other end of capacitor C22 and ground.

[0005] The linear regulated power supply circuit includes a voltage regulator U3. The VIN pin of the voltage regulator U3 is connected to one end of capacitor C29 and the B+ port, respectively. The VOUT pin of the voltage regulator U3 is connected to one end of capacitor C30 and one end of capacitor C31, respectively. The GND pin of the voltage regulator U3, the other end of capacitor C29, the other end of capacitor C30, and the other end of capacitor C31 are connected together to the B- port.

[0006] The MOS drain-source voltage detection circuit includes operational amplifiers U4 and U9. The positive input terminal of operational amplifier U4 is connected to one end of resistor R32 and one end of resistor R34, respectively. The negative input terminal of operational amplifier U4 is connected to one end of resistor R33 and one end of resistor R35, respectively. The positive power supply terminal of operational amplifier U4 is connected to a 5V voltage, and the negative power supply terminal of operational amplifier U4 is grounded. The output terminal of operational amplifier U4 is connected to the other end of resistor R35 and one end of resistor R50, respectively. The other end of resistor R34 is grounded, and the other end of resistor R32 is connected to the port resistor of MOS transistor Q3_D. The other end of R33 is connected to the Q3_S port of the MOSFET. The positive input terminal of the operational amplifier U9 is connected to the other end of the resistor R50 and one end of the capacitor C32. The negative input terminal of the operational amplifier U9 is connected to one end of the resistor R51, one end of the resistor R52 and one end of the capacitor C33. The positive power supply terminal of the operational amplifier U9 is connected to a 5V voltage, and the negative power supply terminal of the operational amplifier U9 is grounded. The output terminal of the operational amplifier U9 is connected to the other end of the resistor R52, the other end of the capacitor C33 and the Vds port. The other end of the capacitor C32 is grounded, and the other end of the resistor R51 is grounded.

[0007] The current sampling and detection circuit includes operational amplifiers U5 and U10. The positive input terminal of operational amplifier U5 is connected to one end of resistor R37 and one end of resistor R39, respectively. The negative input terminal of operational amplifier U5 is connected to one end of resistor R38 and one end of resistor R40, respectively. The positive power supply terminal of operational amplifier U5 is connected to a 5V voltage, and the negative power supply terminal of operational amplifier U5 is grounded. The output terminal of operational amplifier U5 is connected to the other end of resistor R40 and one end of resistor R53, respectively. The other end of resistor R39 is grounded, and the other end of resistor R37 is connected to the VR_11 port. The other end of resistor R38 is connected to port VR_12. The positive input terminal of operational amplifier U10 is connected to the other end of resistor R53 and one end of capacitor C34. The negative input terminal of operational amplifier U10 is connected to one end of resistor R54, one end of resistor R55, and one end of capacitor C35. The positive power supply terminal of operational amplifier U10 is connected to 5V, and the negative power supply terminal of operational amplifier U10 is grounded. The output terminal of operational amplifier U10 is connected to the other end of resistor R55, the other end of capacitor C35, and port Vi. The other end of capacitor C34 is grounded, and the other end of resistor R54 is grounded.

[0008] The proportional mapping circuit includes an operational amplifier U6. The positive input terminal of the operational amplifier U6 is connected to one end of resistor R41 and one end of capacitor C36. The negative input terminal of the operational amplifier U6 is connected to one end of resistor R42 and one end of resistor R56. The positive power supply terminal of the operational amplifier U6 is connected to a 5V voltage, and the negative power supply terminal of the operational amplifier U6 is grounded. The output terminal of the operational amplifier U6 is connected to the other end of resistor R56 and the Vk port. The other end of resistor R42 is grounded, the other end of capacitor C36 is grounded, and the other end of resistor R41 is connected to the Vi port.

[0009] The over-temperature comparison circuit includes a voltage comparator U8. The positive input terminal of the voltage comparator U8 is connected to one end of resistor R46 and one end of capacitor C27. The negative input terminal of the voltage comparator U8 is connected to one end of resistor R47 and one end of capacitor C28. The positive power supply terminal of the voltage comparator U8 is connected to a 5V voltage. The negative power supply terminal of the voltage comparator U8 is connected to port B-. The output terminal of the voltage comparator U8 is connected to one end of resistor R43 and one end of resistor R48. The other end of resistor R48 is connected to one end of resistor R49 and the base of transistor Q9. The collector of transistor Q9 is connected to port TH. The emitter of transistor Q9 and the other end of resistor R49 are combined and connected to port B-. The other end of resistor R43 is connected to port +5. The other ends of capacitor C27 and capacitor C28 are combined and connected to port B-. The other end of resistor R46 is connected to port Vds. The other end of resistor R47 is connected to port Vk.

[0010] The described protection execution circuit includes MOS transistor Q4. The drain of MOS transistor Q4 is connected to one end of fuse J1. The gate of MOS transistor Q4 is respectively connected to one end of resistor R17, one end of resistor R19, and one end of capacitor C7. The other end of resistor R17 is respectively connected to the negative electrodes of diode D8 and diode D9. The source of MOS transistor Q4, the other end of resistor R19, and the other end of capacitor C7 are combined and grounded. The other end of fuse J1 is connected to the F2_Ctr-A port. The positive electrode of diode D8 is connected to the FUSE port. The positive electrode of diode D9 is connected to the MOS transistor Q3_G port.

[0011] The described chip U1 uses the BQ40Z50RSMR-R1 model, and the voltage regulator U3 uses the HT7150-1 model.

[0012] A method for a circuit based on MOS transistor on-resistance temperature detection and protection. The method for this circuit includes the following steps: S1. The system is powered on, and the circuit maintains a stable working power supply; S2. The drain-source voltage Vds and current signal Vi of the MOS transistor are collected in real time; S3. A reference signal Vk is calculated, and its calculation formula is as follows: Vk = K × Vi calculation, where K is a proportionality coefficient; S4. The magnitudes of Vds and Vk are judged in real time. If Vds ≥ Vk, it is judged as an over-temperature state, and step S5 is entered; if Vds < Vk, it is judged as a normal state, and the process returns to step S2 for continuous monitoring; S5. The output node of voltage comparator U8 is pulled up to a high level, and it is judged whether to make transistor Q9 conduct; if the judgment is yes, transistor Q9 conducts, and the system enters the first-level over-temperature protection state and returns to step S2; if the judgment is no, step S six is entered; S6. Transistor Q9 conducts, and it is judged whether to trigger the second-level protection condition. The second-level protection condition is that the comparator U8 continuously outputs an over-temperature signal for more than a preset delay time or the over-temperature state of the MOS transistor is not解除; if the judgment is yes, the fuse is triggered to blow, and the system has permanent failure protection; if the judgment is no, it returns to step S2.

[0013] Compared with the prior art, the present invention reduces the complexity of peripheral devices and wiring, reduces the system cost, uses operational amplifiers and comparators to construct a full analog detection and judgment circuit, does not rely on MCU or software control, effectively avoids the problem of protection failure caused by program anomalies, and constructs an over-temperature protection path independent of the battery management chip. Even if the main control system or fuel gauge fails, reliable protection can still be achieved. A fuse or latch structure is introduced to avoid the risk brought by repeated triggering of traditional recoverable protection, significantly improves the system safety level, is applicable to high-power and high-safety requirement scenarios such as oxygen generators and electric equipment, improves the temperature detection accuracy, realizes independent, fast and non-recoverable over-temperature protection, and significantly enhances the overall safety and reliability of the battery system. Brief Description of the Drawings

[0014] Figure 1 This is a schematic diagram of the overall circuit framework of the present invention; Figure 2 This is a partial circuit diagram of the battery and main power circuit in this invention; Figure 3 This is a partial circuit diagram of the battery and main power circuit in this invention; Figure 4 This is a circuit diagram of the linear voltage regulator power supply circuit in this invention; Figure 5 This is a circuit diagram of the MOS drain-source voltage detection circuit in this invention; Figure 6 This is a circuit diagram of the current sampling and detection circuit in this invention; Figure 7 This is a circuit diagram of the proportional mapping circuit in this invention; Figure 8 This is a circuit diagram of the over-temperature comparison circuit in this invention; Figure 9 This is a circuit diagram of the protection execution circuit in this invention; Figure 10 The temperature change curve is shown in the example. Detailed Implementation

[0015] The present invention will now be further described with reference to the accompanying drawings.

[0016] like Figures 1 to 9A circuit based on MOSFET on-resistance temperature detection and protection includes a battery and main power circuit, a linear voltage regulator circuit, a MOSFET drain-source voltage detection circuit, a current sampling detection circuit, an over-temperature comparator circuit, a proportional mapping circuit, and a protection execution circuit. The B+ port of the battery and main power circuit is connected to the VIN port of the linear voltage regulator circuit. The B- port of the battery and main power circuit is connected to the GND port of the linear voltage regulator circuit, the GND port of the MOSFET drain-source voltage detection circuit, and the GND port of the current sampling detection circuit, respectively. The 5V port of the linear voltage regulator circuit is connected to the 5V ports of the MOSFET drain-source voltage detection circuit, the current sampling detection circuit, the proportional mapping circuit, and the over-temperature comparator circuit, respectively. The VR_11 port of the battery and main power circuit is connected to the VR_11 port of the current sampling detection circuit. The VR_12 port of the battery and main power circuit is connected to the VR_12 port of the current sampling detection circuit. The Q3_D port of the MOSFET in the battery and main power circuit is connected to the MOSFET... The MOSFET Q3_D port of the drain-source voltage detection circuit and the MOSFET Q3_S port of the battery and main power circuit are connected to the MOSFET Q3_S port of the drain-source voltage detection circuit. The FUSE port of the battery and main power circuit are connected to the F2_Ctr-A port of the protection execution circuit and the TH port of the over-temperature comparator circuit, respectively. The Vds port of the over-temperature comparator circuit is connected to the Vds port of the drain-source voltage detection circuit. The Vk port of the over-temperature comparator circuit is connected to the Vk port of the proportional mapping circuit. The Vi port of the proportional mapping circuit is connected to the Vi port of the current sampling detection circuit.

[0017] The battery and main power circuit includes a 5-pin socket (5PIN), chip U1, and chip U2. Chip U1's PBI pin is connected to one end of capacitor C8, with the other end of C8 grounded. Chip U1's VC4 pin is connected to one end of capacitor C15 and one end of resistor R20, with the other end of resistor R20 connected to the B+ port. Chip U1's VC3 pin is connected to the other end of capacitor C15, one end of capacitor C16, and one end of resistor R21, with the other end of resistor R21 connected to the BT3 port. Chip U1's VC2 pin is connected to the other end of capacitor C16, one end of capacitor C17, and one end of resistor R22, with the other end of resistor R22 connected to the BT2 port. Chip U1's VC1 pin is connected to capacitor C15, one end of capacitor C16, one end of capacitor C17, and one end of resistor R22, with the other end of resistor R22 connected to the BT2 port. Chip U1's VC1 pin is connected to capacitor C15, one end of capacitor C16, one end of capacitor C17, and one end of resistor R22, with the other end of resistor R22 connected to the BT2 port. The other end of 7, one end of capacitor C18, and one end of resistor R23 are connected. The other end of resistor R23 is connected to the BT1 port. The other end of capacitor C18 is grounded. The SRN pin of chip U1 is connected to one end of capacitor C11, one end of capacitor C14, and one end of resistor R24. The other end of capacitor C14 is grounded. The NC pin and VSS pin of chip U1 are grounded together. The SRP pin of chip U1 is connected to the other end of capacitor C11, one end of capacitor C13, and one end of resistor R31. The other end of resistor R31 is connected to one end of resistor R25 (B-port). The TS1 pin of chip U1 is connected to one end of resistor RT2. The #PRES / #SHUTDN pins of chip U1 are connected to resistor R One end of resistor R16, the other end of resistor R2, the other end of resistor R16, the TS2 pin, the TS3 pin, and the TS4 pin of chip U1 are connected to ground. The #DISP pin of chip U1 is connected to one end of resistor R12. The other end of resistor R12 is connected to one end of capacitor C6 and one end of switch S1. The other end of capacitor C6 and the other end of switch S1 are connected to ground. The SMBD pin of chip U1 is connected to one end of resistor R8. The other end of resistor R8 is connected to one end of resistor R4, one end of resistor R1, and one end of diode D2. The other end of resistor R1 is connected to the SDA port. The SMBC pin of chip U1 is connected to one end of resistor R7. The other end of resistor R7 is connected to... One end of resistor R6, one end of resistor R2, and one end of diode D2 are connected. The other end of resistor R2 is connected to the SCK port. The other ends of resistors R24, R25, R4, R6, and diode D2, along with one end of capacitor C2, are connected together to the P- port and ground, respectively. The LEDCNTLA pin of chip U1 is connected to the cathode of diode D4 and the anode of diode D1, respectively. The LEDCNTLB pin of chip U1 is connected to the anodes of diodes D4 and D5, the cathode of diode D6, and the cathode of diode D1, respectively. The LEDCNTLC pin of chip U1 is connected to the cathode of diode D5 and the anode of diode D6, respectively.The PTC pin of chip U1 is connected to one end of resistor RTC1 and one end of capacitor C5. The PTCEN pin of chip U1 is connected to the other end of resistor RTC1, the other end of capacitor C5, and the B+ port. The VCC pin of chip U1 is connected to one end of resistor R11. The PACK pin of chip U1 is connected to one end of resistor R3. The DSG pin of chip U1 is connected to one end of resistor R10. The PCHG pin of chip U1 is connected to one end of resistor R14. The CHG pin of chip U1 is connected to one end of resistor R13. The BAT pin of chip U1 is connected to one end of diode D7. The source of MOSFET Q3 is connected to one end of resistor R15, one end of capacitor C4, one end of protector F1, and the S port of MOSFET Q3. The gate of MOSFET Q3 is connected to the other ends of resistors R13 and R15. One end of protector F1 is connected to the cathodes of diodes D10 and D11. The anode of diode D10 is connected to the TH interface, and the anode of diode D11 is connected to the F2_Ctr-A interface. The other ends of protector F1, diode D7, and resistor R20 are combined and connected to the B+ port. The drain of MOSFET Q3 is connected to the Q3_D port, the other end of resistor R14, and the other end of resistor R11. The drain of MOSFET Q2 and the source of MOSFET Q2 are connected to one end of resistor R9, the source of MOSFET Q1, one end of capacitor C3, one end of resistor R36, and diode D3. One end of the resistor R1 is connected to the VR_11 port. The other end of capacitor C3 is connected to the other end of capacitor C4. The gate of MOSFET Q2 is connected to the other end of resistor R9, the other end of resistor R10, and the drain of MOSFET Q1. The gate of MOSFET Q1 is connected to the other end of diode D3 and one end of resistor R5. The other end of resistor R5 is grounded. The other end of resistor R36 is connected to the other end of resistor R3, one end of capacitor C1, the VR_12 port, and the P+ port. The other end of capacitor C1 is connected to the other end of capacitor C2. Pin 1 of the 5-pin socket is connected to the P+ port. Pin 2 of the 5-pin socket is connected to the SCK port. Pin 3 of the 5-pin socket is connected to the SDA port. Pin 4 of the chip is connected to one end of resistor RT1 and the TS1 port, respectively. The other end of resistor RT1 is connected to the P- port. Pin 5 of the 5-pin socket is connected to the P- port. The VCC pin of chip U2 is connected to one end of capacitor C12 and one end of resistor R26, respectively. The other end of capacitor C12 is grounded, and the other end of resistor R26 is connected to the B+ port. The ICT pin of chip U2 is connected to one end of capacitor C9, and the other end of capacitor C9 is connected to one end of capacitor C10, the other end of capacitor C10 is grounded. The CO pin of chip U2 is connected to one end of resistor R18, and the other end of resistor R18 is connected to the Q3_G port of MOSFET. The SENSE pin of chip U2 is connected to one end of resistor R27 and one end of capacitor C19, respectively.The other end of resistor R27 is connected to the B+ port. The VC1 pin of chip U2 is connected to the other end of capacitor C19, one end of resistor R28, and one end of capacitor C20. The other end of resistor R28 is connected to the BT3 port. The VC2 pin of chip U2 is connected to the other end of capacitor C20, one end of resistor R29, and one end of capacitor C21. The other end of resistor R29 is connected to the BT2 port. The VC3 pin of chip U2 is connected to the other end of capacitor C21, one end of resistor R30, and one end of capacitor C22. The other end of resistor R30 is connected to the BT1 port. The VSS pin of chip U2 is connected to the other end of capacitor C22 and ground. When the comparator output is high, the transistor conducts, pulling the control node low and achieving FUSE shutdown. A pull-down resistor is set at the base to prevent false triggering and to transmit the over-temperature protection signal to the system control.

[0018] The linear voltage regulator circuit includes regulator U3. The VIN pin of regulator U3 is connected to one end of capacitor C29 and the B+ port, respectively. The VOUT pin of regulator U3 is connected to one end of capacitor C30 and one end of capacitor C31, respectively. The GND pin of regulator U3, the other end of capacitor C29, the other end of capacitor C30, and the other end of capacitor C31 are combined and connected to the B- port. The battery pack is input to regulator U3, which steps down the input voltage to output a stable low-voltage power supply (e.g., 5V) to power the subsequent operational amplifier and comparator. A filter capacitor is installed at the input to suppress battery-side voltage fluctuations and high-frequency interference, improving system stability. A decoupling capacitor is configured at the output to reduce power supply ripple and ensure the stability of the operational amplifier and comparator. An independent and stable power supply is provided to avoid interference from the main power circuit.

[0019] The MOS drain-source voltage detection circuit includes operational amplifiers U4 and U9. The positive input terminal of operational amplifier U4 is connected to one end of resistor R32 and one end of resistor R34, respectively. The negative input terminal of operational amplifier U4 is connected to one end of resistor R33 and one end of resistor R35, respectively. The positive power supply terminal of operational amplifier U4 is connected to a 5V voltage, and the negative power supply terminal of operational amplifier U4 is grounded. The output terminal of operational amplifier U4 is connected to the other end of resistor R35 and one end of resistor R50, respectively. The other end of resistor R34 is grounded, and the other end of resistor R32 is connected to the port resistor of MOS transistor Q3_D. The other end of R33 is connected to the Q3_S port of the MOSFET. The positive input terminal of the operational amplifier U9 is connected to the other end of the resistor R50 and one end of the capacitor C32. The negative input terminal of the operational amplifier U9 is connected to one end of the resistor R51, one end of the resistor R52 and one end of the capacitor C33. The positive power supply terminal of the operational amplifier U9 is connected to a 5V voltage, and the negative power supply terminal of the operational amplifier U9 is grounded. The output terminal of the operational amplifier U9 is connected to the other end of the resistor R52, the other end of the capacitor C33 and the Vds port. The other end of the capacitor C32 is grounded, and the other end of the resistor R51 is grounded. Detection nodes are led out from both ends of the MOSFET, and a differential sampling structure is formed through a resistor network to detect the drain-source voltage Vds. Matching resistors are used to proportionally attenuate the Vds signal to adapt to the input range of the subsequent operational amplifier. The differential signal is input to the operational amplifier, and the amplification circuit boosts the millivolt-level signal to a processable voltage range. An RC filter network is set at the input to filter out switching noise and high-frequency interference, improving detection accuracy. The output terminal obtains a signal proportional to the MOSFET's turn-on voltage for subsequent judgment.

[0020] The current sampling and detection circuit includes operational amplifiers U5 and U10. The positive input terminal of operational amplifier U5 is connected to one end of resistor R37 and one end of resistor R39, respectively. The negative input terminal of operational amplifier U5 is connected to one end of resistor R38 and one end of resistor R40, respectively. The positive power supply terminal of operational amplifier U5 is connected to a 5V voltage, and the negative power supply terminal of operational amplifier U5 is grounded. The output terminal of operational amplifier U5 is connected to the other end of resistor R40 and one end of resistor R53, respectively. The other end of resistor R39 is grounded, and the other end of resistor R37 is connected to the VR_11 port. The other end of 38 is connected to the VR_12 port. The positive input terminal of operational amplifier U10 is connected to the other end of resistor R53 and one end of capacitor C34. The negative input terminal of operational amplifier U10 is connected to one end of resistor R54, one end of resistor R55, and one end of capacitor C35. The positive power supply terminal of operational amplifier U10 is connected to a 5V voltage, and the negative power supply terminal of operational amplifier U10 is grounded. The output terminal of operational amplifier U10 is connected to the other end of resistor R55, the other end of capacitor C35, and the Vi port. The other end of capacitor C34 and the other end of resistor R54 are grounded. A sampling resistor is connected in series in the main circuit to obtain the current information flowing through the MOSFET. The voltage across the sampling resistor is detected through a differential resistor network to form a current detection signal. The differential signal is amplified by an operational amplifier to obtain a voltage signal Vi proportional to the current. An RC filter circuit is set in the detection path to suppress transient interference caused by current changes.

[0021] The proportional mapping circuit includes operational amplifier U6. The positive input terminal of operational amplifier U6 is connected to one end of resistor R41 and one end of capacitor C36, respectively. The negative input terminal of operational amplifier U6 is connected to one end of resistor R42 and one end of resistor R56, respectively. The positive power supply terminal of operational amplifier U6 is connected to a 5V voltage, and the negative power supply terminal of operational amplifier U6 is grounded. The output terminal of operational amplifier U6 is connected to the other end of resistor R56 and the Vk port, respectively. The other end of resistor R42 and capacitor C36 are grounded, and the other end of resistor R41 is connected to the Vi port. Using a non-inverting operational amplifier structure, the current signal Vi is converted into a reference signal Vk. The proportional coefficient K is set by the ratio of the feedback resistor to the input resistor, Vk = K × Vi. The proportional coefficient K is set according to the on-resistance of the MOSFET at the target temperature (e.g., 85℃), generating a voltage signal that monotonically corresponds to the change in on-resistance, achieving a voltage equivalent expression of the temperature threshold. This structure can automatically offset the influence of current changes, improving the accuracy of temperature judgment.

[0022] The over-temperature comparator circuit includes a voltage comparator U8. The positive input terminal of voltage comparator U8 is connected to one end of resistor R46 and one end of capacitor C27. The negative input terminal of voltage comparator U8 is connected to one end of resistor R47 and one end of capacitor C28. The positive power supply terminal of voltage comparator U8 is connected to 5V. The negative power supply terminal of voltage comparator U8 is connected to port B-. The output terminal of voltage comparator U8 is connected to one end of resistor R43 and one end of resistor R48. The other end of resistor R48 is connected to one end of resistor R49 and the base of transistor Q9. The collector of transistor Q9 is connected to port TH. The emitter of transistor Q9 and the other end of resistor R49 are combined and connected to port B-. The other end of resistor R43 is connected to port +5. The other ends of capacitors C27 and C28 are combined and connected to port B-. The other end of resistor R46 is connected to port Vds. The other end of resistor R47 is connected to port Vk.

[0023] An over-temperature threshold is determined using a comparator, generating an over-temperature signal. The comparator output uses pull-up resistors to achieve a level output, improving anti-interference capability. A filter capacitor is placed at the input to prevent false triggering due to signal jitter.

[0024] The protection circuit includes a MOSFET Q4. The drain of MOSFET Q4 is connected to one end of fuse J1. The gate of MOSFET Q4 is connected to one end of resistor R17, one end of resistor R19, and one end of capacitor C7. The other end of resistor R17 is connected to the cathodes of diodes D8 and D9. The source of MOSFET Q4, the other end of resistor R19, and the other end of capacitor C7 are grounded. The other end of fuse J1 is connected to port F2_Ctr-A. The anode of diode D8 is connected to the FUSE port, and the anode of diode D9 is connected to port Q3_G of MOSFET Q3. When the over-temperature signal persists, the fuse is triggered, permanently disconnecting the main circuit. After the circuit blows, it cannot be restored and requires replacement or repair to resume operation. As a secondary protection measure, it provides final safety assurance in case of main protection failure or abnormality. This method is independent of the battery management chip and does not rely on software control.

[0025] Chip U1 is model BQ40Z50RSMR-R1, and voltage regulator U3 is model HT7150-1.

[0026] A method for temperature detection and protection based on the on-resistance of a MOSFET circuit, the method comprising the following steps: S1, system power supply, the circuit maintains a stable operating power supply; S2. Real-time acquisition of MOSFET drain-source voltage Vds and current signal Vi; S3. Calculate the reference signal Vk, and its calculation formula is as follows: Vk=K×Vi, where K is the proportional coefficient; S4. Continuously judge the magnitudes of Vds and Vk. If Vds ≥ Vk, it is judged as an over-temperature state, and proceed to step S5; if Vds < Vk, it is judged as a normal state, and return to step S2 to continue monitoring; S5. The output node of voltage comparator U8 is pulled up to a high level, and judge whether to turn on transistor Q9; if the judgment is yes, then transistor Q9 is turned on, and the system enters the first-level over-temperature protection state and returns to step S2; if the judgment is no, then proceed to step S6; S6. Transistor Q9 is turned on, and judge whether to trigger the second-level protection condition. The second-level protection condition is that the comparator U8 continuously outputs an over-temperature signal exceeding a preset delay time or the over-temperature state of the MOS transistor is not解除; if the judgment is yes, then trigger the fuse to blow, and the system has permanent failure protection; if the judgment is no, then return to step S2.

[0027] Such as Figure 10 , under different current conditions (5A, 10A, 15A), the Vds signal shows an upward trend as the temperature rises, while the proportional mapping signal Vk maintains a proportional relationship with the current. When the temperature reaches the set threshold of 85°C, the judgment condition of Vds ≥ Vk is satisfied under each working condition, triggering the comparator output, and stable and consistent over-temperature detection can be achieved under different load conditions.

Claims

1. A circuit for temperature detection and protection based on the on-resistance of a MOSFET, comprising a battery and main power circuit, a linear voltage regulator circuit, a MOSFET drain-source voltage detection circuit, a current sampling detection circuit, an over-temperature comparison circuit, a proportional mapping circuit, and a protection execution circuit, characterized in that: The B+ port of the battery and main power circuit is connected to the VIN port of the linear regulator power supply circuit. The B- port of the battery and main power circuit is connected to the GND port of the linear regulator power supply circuit, the GND port of the MOS drain-source voltage detection circuit, and the GND port of the current sampling detection circuit, respectively. The 5V port of the linear regulator power supply circuit is connected to the 5V port of the MOS drain-source voltage detection circuit, the 5V port of the current sampling detection circuit, the 5V port of the proportional mapping circuit, and the 5V port of the over-temperature comparator circuit, respectively. The VR_11 port of the battery and main power circuit is connected to the VR_11 port of the current sampling detection circuit. The VR_12 port of the battery and main power circuit is connected to the VR_12 port of the current sampling detection circuit. The Q3_D port of the MOS transistor in the battery and main power circuit is connected to the Q3_D port of the MOS transistor in the MOS drain-source voltage detection circuit. The Q3_S port of the MOS transistor in the battery and main power circuit is connected to the MOS transistor in the MOS drain-source voltage detection circuit. The MOSFET Q3_S port of the drain-source voltage detection circuit and the FUSE port of the battery and main power circuit are connected to the F2_Ctr-A port of the protection execution circuit and the TH port of the over-temperature comparator circuit, respectively. The Vds port of the over-temperature comparator circuit is connected to the Vds port of the MOSFET drain-source voltage detection circuit. The Vk port of the over-temperature comparator circuit is connected to the Vk port of the proportional mapping circuit. The Vi port of the proportional mapping circuit is connected to the Vi port of the current sampling detection circuit.

2. The circuit for temperature detection and protection based on the on-resistance of a MOSFET according to claim 1, characterized in that: The battery and main power circuit includes a 5-pin socket (5PIN), chip U1, and chip U2. The PBI pin of chip U1 is connected to one end of capacitor C8, and the other end of capacitor C8 is grounded. The VC4 pin of chip U1 is connected to one end of capacitor C15 and one end of resistor R20, with the other end of resistor R20 connected to the B+ port. The VC3 pin of chip U1 is connected to the other end of capacitor C15, one end of capacitor C16, and one end of resistor R21, with the other end of resistor R21 connected to the BT3 port. The VC2 pin of chip U1 is connected to the other end of capacitor C16, one end of capacitor C17, and one end of resistor R22, with the other end of resistor R22 connected to the BT2 port. The VC1 pin of chip U1 is connected to capacitor C15, one end of capacitor C16, one end of capacitor C17, and one end of resistor R22, with the other end of resistor R22 connected to the BT2 port. The other end of C17, one end of capacitor C18, and one end of resistor R23 are connected. The other end of resistor R23 is connected to the BT1 port. The other end of capacitor C18 is grounded. The SRN pin of chip U1 is connected to one end of capacitor C11, one end of capacitor C14, and one end of resistor R24. The other end of capacitor C14 is grounded. The NC pin and VSS pin of chip U1 are grounded together. The SRP pin of chip U1 is connected to the other end of capacitor C11, one end of capacitor C13, and one end of resistor R31. The other end of resistor R31 is connected to one end of resistor R25 (B-port). The TS1 pin of chip U1 is connected to one end of resistor RT2. The #PRES / #SHUTDN pins of chip U1 are connected to... One end of resistor R16, the other end of resistor RT2, the other end of resistor R16, the TS2 pin, TS3 pin, and TS4 pin of chip U1 are connected to ground. The #DISP pin of chip U1 is connected to one end of resistor R12. The other end of resistor R12 is connected to one end of capacitor C6 and one end of switch S1. The other end of capacitor C6 and the other end of switch S1 are connected to ground. The SMBD pin of chip U1 is connected to one end of resistor R8. The other end of resistor R8 is connected to one end of resistor R4, one end of resistor R1, and one end of diode D2. The other end of resistor R1 is connected to the SDA port. The SMBC pin of chip U1 is connected to one end of resistor R7. The other end of resistor R7 is connected to... Connect one end of resistor R6, one end of resistor R2, and one end of diode D2. Connect the other end of resistor R2 to the SCK port. Connect the other ends of resistors R24, R25, R4, R6, and diode D2, along with one end of capacitor C2, to the P- port and ground respectively. Connect the LEDCNTLA pin of chip U1 to the cathode of diode D4 and the anode of diode D1. Connect the LEDCNTLB pin of chip U1 to the anodes of diodes D4, D5, D6, and D1 respectively. Connect the LEDCNTLC pin of chip U1 to the cathode of diode D5 and the anode of diode D6 respectively.The PTC pin of chip U1 is connected to one end of resistor RTC1 and one end of capacitor C5. The PTCEN pin of chip U1 is connected to the other end of resistor RTC1, the other end of capacitor C5, and the B+ port. The VCC pin of chip U1 is connected to one end of resistor R11. The PACK pin of chip U1 is connected to one end of resistor R3. The DSG pin of chip U1 is connected to one end of resistor R10. The PCHG pin of chip U1 is connected to one end of resistor R14. The CHG pin of chip U1 is connected to one end of resistor R13. The BAT pin of chip U1 is connected to one end of diode D7. The source of MOSFET Q3 is connected to one end of resistor R15, one end of capacitor C4, one end of protector F1, and the S port of MOSFET Q3. The gate of MOSFET Q3 is connected to the other ends of resistors R13 and R15. One end of protector F1 is connected to the cathodes of diodes D10 and D11. The anode of diode D10 is connected to the TH interface, and the anode of diode D11 is connected to the F2_Ctr-A interface. The other ends of protector F1, diode D7, and resistor R20 are combined and connected to the B+ port. The drain of MOSFET Q3 is connected to the Q3_D port, the other end of resistor R14, and the other end of resistor R11. The drain of MOSFET Q2 and the source of MOSFET Q2 are connected to one end of resistor R9, the source of MOSFET Q1, one end of capacitor C3, one end of resistor R36, and diode D3. One end of the resistor R1 is connected to the VR_11 port. The other end of capacitor C3 is connected to the other end of capacitor C4. The gate of MOSFET Q2 is connected to the other end of resistor R9, the other end of resistor R10, and the drain of MOSFET Q1. The gate of MOSFET Q1 is connected to the other end of diode D3 and one end of resistor R5. The other end of resistor R5 is grounded. The other end of resistor R36 is connected to the other end of resistor R3, one end of capacitor C1, the VR_12 port, and the P+ port. The other end of capacitor C1 is connected to the other end of capacitor C2. Pin 1 of the 5-pin socket is connected to the P+ port. Pin 2 of the 5-pin socket is connected to the SCK port. Pin 3 of the 5-pin socket is connected to the SDA port. Pin 4 of the chip is connected to one end of resistor RT1 and the TS1 port, respectively. The other end of resistor RT1 is connected to the P- port. Pin 5 of the 5-pin socket is connected to the P- port. The VCC pin of chip U2 is connected to one end of capacitor C12 and one end of resistor R26, respectively. The other end of capacitor C12 is grounded, and the other end of resistor R26 is connected to the B+ port. The ICT pin of chip U2 is connected to one end of capacitor C9, and the other end of capacitor C9 is connected to one end of capacitor C10, the other end of capacitor C10 is grounded. The CO pin of chip U2 is connected to one end of resistor R18, and the other end of resistor R18 is connected to the Q3_G port of MOSFET. The SENSE pin of chip U2 is connected to one end of resistor R27 and one end of capacitor C19, respectively.The other end of resistor R27 is connected to the B+ port. The VC1 pin of chip U2 is connected to the other end of capacitor C19, one end of resistor R28, and one end of capacitor C20. The other end of resistor R28 is connected to the BT3 port. The VC2 pin of chip U2 is connected to the other end of capacitor C20, one end of resistor R29, and one end of capacitor C21. The other end of resistor R29 is connected to the BT2 port. The VC3 pin of chip U2 is connected to the other end of capacitor C21, one end of resistor R30, and one end of capacitor C22. The other end of resistor R30 is connected to the BT1 port. The VSS pin of chip U2 is connected to the other end of capacitor C22 and ground.

3. The circuit for temperature detection and protection based on the on-resistance of a MOSFET according to claim 1, characterized in that: The linear regulated power supply circuit includes a voltage regulator U3. The VIN pin of the voltage regulator U3 is connected to one end of capacitor C29 and the B+ port, respectively. The VOUT pin of the voltage regulator U3 is connected to one end of capacitor C30 and one end of capacitor C31, respectively. The GND pin of the voltage regulator U3, the other end of capacitor C29, the other end of capacitor C30, and the other end of capacitor C31 are connected together to the B- port.

4. The circuit for temperature detection and protection based on the on-resistance of a MOSFET according to claim 1, characterized in that: The MOS drain-source voltage detection circuit includes operational amplifiers U4 and U9. The positive input terminal of operational amplifier U4 is connected to one end of resistor R32 and one end of resistor R34, respectively. The negative input terminal of operational amplifier U4 is connected to one end of resistor R33 and one end of resistor R35, respectively. The positive power supply terminal of operational amplifier U4 is connected to a 5V voltage, and the negative power supply terminal of operational amplifier U4 is grounded. The output terminal of operational amplifier U4 is connected to the other end of resistor R35 and one end of resistor R50, respectively. The other end of resistor R34 is grounded, and the other end of resistor R32 is connected to the port resistor of MOS transistor Q3_D. The other end of R33 is connected to the Q3_S port of the MOSFET. The positive input terminal of the operational amplifier U9 is connected to the other end of the resistor R50 and one end of the capacitor C32. The negative input terminal of the operational amplifier U9 is connected to one end of the resistor R51, one end of the resistor R52 and one end of the capacitor C33. The positive power supply terminal of the operational amplifier U9 is connected to a 5V voltage, and the negative power supply terminal of the operational amplifier U9 is grounded. The output terminal of the operational amplifier U9 is connected to the other end of the resistor R52, the other end of the capacitor C33 and the Vds port. The other end of the capacitor C32 is grounded, and the other end of the resistor R51 is grounded.

5. The circuit for temperature detection and protection based on the on-resistance of a MOSFET according to claim 1, characterized in that: The current sampling and detection circuit includes operational amplifiers U5 and U10. The positive input terminal of operational amplifier U5 is connected to one end of resistor R37 and one end of resistor R39, respectively. The negative input terminal of operational amplifier U5 is connected to one end of resistor R38 and one end of resistor R40, respectively. The positive power supply terminal of operational amplifier U5 is connected to a 5V voltage, and the negative power supply terminal of operational amplifier U5 is grounded. The output terminal of operational amplifier U5 is connected to the other end of resistor R40 and one end of resistor R53, respectively. The other end of resistor R39 is grounded, and the other end of resistor R37 is connected to the VR_11 port. The other end of resistor R38 is connected to port VR_12. The positive input terminal of operational amplifier U10 is connected to the other end of resistor R53 and one end of capacitor C34. The negative input terminal of operational amplifier U10 is connected to one end of resistor R54, one end of resistor R55, and one end of capacitor C35. The positive power supply terminal of operational amplifier U10 is connected to 5V, and the negative power supply terminal of operational amplifier U10 is grounded. The output terminal of operational amplifier U10 is connected to the other end of resistor R55, the other end of capacitor C35, and port Vi. The other end of capacitor C34 is grounded, and the other end of resistor R54 is grounded.

6. The circuit for temperature detection and protection based on the on-resistance of a MOSFET according to claim 1, characterized in that: The proportional mapping circuit includes an operational amplifier U6. The positive input terminal of the operational amplifier U6 is connected to one end of resistor R41 and one end of capacitor C36. The negative input terminal of the operational amplifier U6 is connected to one end of resistor R42 and one end of resistor R56. The positive power supply terminal of the operational amplifier U6 is connected to a 5V voltage, and the negative power supply terminal of the operational amplifier U6 is grounded. The output terminal of the operational amplifier U6 is connected to the other end of resistor R56 and the Vk port. The other end of resistor R42 is grounded, the other end of capacitor C36 is grounded, and the other end of resistor R41 is connected to the Vi port.

7. The circuit for temperature detection and protection based on the on-resistance of a MOSFET according to claim 1, characterized in that: The over-temperature comparison circuit includes a voltage comparator U8. The positive input terminal of the voltage comparator U8 is connected to one end of resistor R46 and one end of capacitor C27. The negative input terminal of the voltage comparator U8 is connected to one end of resistor R47 and one end of capacitor C28. The positive power supply terminal of the voltage comparator U8 is connected to a 5V voltage. The negative power supply terminal of the voltage comparator U8 is connected to port B-. The output terminal of the voltage comparator U8 is connected to one end of resistor R43 and one end of resistor R48. The other end of resistor R48 is connected to one end of resistor R49 and the base of transistor Q9. The collector of transistor Q9 is connected to port TH. The emitter of transistor Q9 and the other end of resistor R49 are combined and connected to port B-. The other end of resistor R43 is connected to port +5. The other ends of capacitor C27 and capacitor C28 are combined and connected to port B-. The other end of resistor R46 is connected to port Vds. The other end of resistor R47 is connected to port Vk.

8. The circuit for temperature detection and protection based on the on-resistance of a MOSFET according to claim 1, characterized in that: The described protection execution circuit includes a MOS transistor Q4. The drain of the MOS transistor Q4 is connected to one end of a fuse J1. The gate of the MOS transistor Q4 is respectively connected to one end of a resistor R17, one end of a resistor R19, and one end of a capacitor C7. The other end of the resistor R17 is respectively connected to the negative electrodes of a diode D8 and a diode D9. The source of the MOS transistor Q4, the other end of the resistor R19, and the other end of the capacitor C7 are combined and grounded. The other end of the fuse J1 is connected to the F2_Ctr-A port. The positive electrode of the diode D8 is connected to the FUSE port. The positive electrode of the diode D9 is connected to the MOS transistor Q3_G port.

9. The circuit for temperature detection and protection based on the on-resistance of a MOSFET according to claim 1, characterized in that: The described chip U1 uses the model BQ40Z50RSMR-R1, and the voltage regulator U3 uses the model HT7150-1.

10. A method for detecting and protecting the temperature based on the on-resistance of a MOSFET as described in any one of claims 1-9, characterized in that: The method of the described circuit includes the following steps: S1. The system is powered on, and the circuit maintains a stable working power supply; S2. The drain-source voltage Vds and the current signal Vi of the MOS transistor are collected in real time; S3. A reference signal Vk is calculated, and its calculation formula is as follows: Vk = K × Vi, where K is a proportionality coefficient; S4. The magnitudes of Vds and Vk are judged in real time. If Vds ≥ Vk, it is judged as an over-temperature state, and step S5 is entered; if Vds < Vk, it is judged as a normal state, and the process returns to step S2 to continue monitoring; S5. The output node of the voltage comparator U8 is pulled up to a high level, and it is judged whether the transistor Q9 is turned on; if the judgment is yes, the transistor Q9 is turned on, and the system enters the first-level over-temperature protection state and returns to step S2; if the judgment is no, step S6 is entered; S,6. The transistor Q9 is turned on, and it is judged whether the second-level protection condition is triggered. The second-level protection condition is that the comparator U8 continuously outputs an over-temperature signal for more than a preset delay time or the over-temperature state of the MOS transistor is not解除; if the judgment is yes, the fuse is triggered to blow, and the system has permanent failure protection; if the judgment is no, the process returns to step S2.

Images