A protection circuit for preventing a load switch from being burned out by heat

Abstract

The present invention provides a protection circuit for preventing a load switch from being burned by heat. A plurality of branches are connected in parallel. In each parallel branch, one end of a current source IDC is connected to a power input terminal VCC, the other end of the current source IDC is connected to one end of an inverter INV and the collector of a transistor, the base of the transistor is connected to the positive terminal of a voltage source VDC, the emitter of the transistor is grounded, and the other end of the reflector is connected to the input terminal of an OR gate OR. The present invention selects many points around the power tube, and can accurately detect temperature changes in multiple directions. When temperature changes occur in any part of the power tube, it can be detected in real time. The number of temperature sensors is selected according to the specific conditions inside the circuit, and they are arranged around the power tube according to a certain sorting method, which can more effectively control the internal temperature of the chip, thereby protecting the chip.

Description

Technical Field

[0001] The invention relates to the field of protection circuits, in particular to a protection structure and method for preventing thermal burnout. Background Art

[0002] With the continuous integration of chips, high-power devices are often used in power management chips, which has strict requirements on the temperature of the chip to prevent accidents caused by excessive temperature. At present, most chips use built-in temperature sensors inside the chip to detect the temperature of the power tube to prevent the power tube from burning due to excessive temperature. However, the current technical methods also have some problems, such as Figure 1 As shown, the solid-line frame is a schematic diagram of the power tube position, and the dotted-line frame is a schematic diagram of the temperature sensor position. Generally, the temperature sensor is placed on one side of the power tube for temperature detection. Since the power tube occupies a large area in the chip, the temperature of each part is different. Generally, the temperature at the center of the power tube is higher than the temperature on both sides. However, since the temperature sensor can only detect the temperature on one side of the power tube, it cannot detect the actual temperature inside the power tube, causing deviation in temperature detection, which may also burn the power tube.

[0003] Therefore, it is necessary to develop a protection circuit that can accurately detect the temperature of the power tube and further accurately monitor the temperature inside the chip to avoid further losses caused by chip burning. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, the present invention provides a protection circuit for preventing a load switch from being burned by heat. The circuit can accurately detect the real-time temperature inside the power tube at multiple locations inside the chip of the load switch, thereby controlling whether the chip continues to work. The circuit inside the chip can be effectively shut down in time when the temperature is too high, thereby solving the shortcomings of the above-mentioned traditional temperature detection.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] A protection circuit for preventing a load switch from being burned by heat, comprising an input terminal VCC, a voltage source VDC, current sources IDC1, IDC2, IDC3, transistors Q1, Q2, Q3 with negative temperature coefficients, inverters INV1, INV2, INV3, an OR gate OR and an output terminal VOUT;

[0007] The power input terminal VCC is connected to one end of the current source IDC1, one end of the current source IDC2 and one end of the current source IDC3; the other end of the current source IDC1 is connected to one end of the inverter INV1 and the collector of the transistor Q1; the other end of the current source IDC2 is connected to one end of the inverter INV2 and the collector of the transistor Q2; the other end of the current source IDC3 is connected to one end of the inverter INV3 and the collector of the transistor Q3; the voltage source VDC is the regulator voltage, and the positive end of the voltage source VDC is connected to the transistors Q1 and Q 2. The base of Q3 and the negative terminal of the voltage source VDC are grounded; the base of the transistor Q1 is connected to the positive terminal of the voltage source VDC, the collector is connected to the other end of the current source IDC1 and one end of the inverter INV1, and the emitter is grounded; the base of the transistor Q2 is connected to the positive terminal of the voltage source VDC, the collector is connected to the other end of the current source IDC2 and one end of the inverter INV2, and the emitter is grounded; the base of the transistor Q3 is connected to the positive terminal of the voltage source VDC, the collector is connected to the other end of the current source IDC3 and one end of the inverter INV3, and the emitter is grounded;

[0008] One end of the inverter INV1 is connected to the other end of the current source IDC1 and the collector of the transistor Q1, and the other end is connected to the input end of the OR gate OR; one end of the inverter INV2 is connected to the other end of the current source IDC2 and the collector of the transistor Q2, and the other end is connected to the input end of the OR gate OR; one end of the inverter INV3 is connected to the other end of the current source IDC3 and the collector of the transistor Q3, and the other end is connected to the input end of the OR gate OR; the input end of the OR gate OR is respectively connected to the other end of the inverter INV1, the other end of INV2 and the other end of INV3, and the output end of the OR gate OR is connected to the output port VOUT of the over-temperature protection circuit.

[0009] Furthermore, the transistors Q1, Q2 and Q3 act as temperature sensors, and multiple parallel branches can be added according to actual circuit requirements, and the transistors in the parallel branches are evenly distributed on the power tube to detect the temperature of the power tube; in each parallel branch, one end of the current source IDC is connected to the power input terminal VCC, the other end of the current source IDC is connected to one end of the inverter INV and the collector of the transistor, the base of the transistor is connected to the positive end of the voltage source VDC, the emitter of the transistor is grounded, and the other end of the reflector is connected to the input end of the OR gate OR.

[0010] The beneficial effects of the present invention are:

[0011] 1. Many points are selected around the power tube, which can accurately detect temperature changes in all directions. When the temperature changes in any part of the power tube, it can be detected in real time.

[0012] 2. Select the number of temperature sensors according to the specific situation inside the circuit, and arrange them around the power tube in a certain sorting method, which can more effectively control the internal temperature of the chip and thus protect the chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Schematic diagram of the position relationship between traditional temperature sensors and power tubes.

[0014] Figure 2 The circuit diagram of the protection structure for preventing a load switch from being burned out by heat according to the present invention.

[0015] Figure 3 It is a schematic diagram of the position relationship between the temperature sensor and the power tube of the present invention. DETAILED DESCRIPTION

[0016] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0017] A protection circuit to prevent a load switch from being burned out by heat. Figure 2 As shown, it includes an input terminal VCC, a voltage source VDC, current sources IDC1, IDC2, IDC3, transistors Q1, Q2, Q3 of a temperature sensor with a negative temperature coefficient, inverters INV1, INV2, INV3, an OR gate OR and an output terminal VOUT.

[0018] The power input terminal VCC is connected to one end of the current source IDC1, one end of the current source IDC2 and one end of the current source IDC3; the other end of the current source IDC1 is connected to one end of the inverter INV1 and the collector of the transistor Q1; the other end of the current source IDC2 is connected to one end of the inverter INV2 and the collector of the transistor Q2; the other end of the current source IDC3 is connected to one end of the inverter INV3 and the collector of the transistor Q3; the voltage source VDC is Figure 2 In the actual application of the circuit shown, the Regulator voltage provided by other parts of the chip, the positive end of the voltage source VDC is connected to the bases of the transistors Q1, Q2, and Q3, and the negative end of the voltage source VDC is grounded; the base of the transistor Q1 is connected to the positive end of the voltage source VDC, the collector is connected to the other end of the current source IDC1 and one end of the inverter INV1, and the emitter is grounded; the base of the transistor Q2 is connected to the positive end of the voltage source VDC, the collector is connected to the other end of the current source IDC2 and one end of the inverter INV2, and the emitter is grounded; the base of the transistor Q3 is connected to the positive end of the voltage source VDC, the collector is connected to the other end of the current source IDC3 and one end of the inverter INV3, and the emitter is grounded;

[0019] One end of the inverter INV1 is connected to the other end of the current source IDC1 and the collector of the transistor Q1, and the other end is connected to the input end of the OR gate OR; one end of the inverter INV2 is connected to the other end of the current source IDC2 and the collector of the transistor Q2, and the other end is connected to the input end of the OR gate OR; one end of the inverter INV3 is connected to the other end of the current source IDC3 and the collector of the transistor Q3, and the other end is connected to the input end of the OR gate OR; the input end of the OR gate OR is respectively connected to the other end of the inverter INV1, the other end of INV2 and the other end of INV3, and the output end of the OR gate OR is connected to the output port VOUT of the over-temperature protection circuit.

[0020] Furthermore, the transistors Q1, Q2 and Q3 act as temperature sensors, and multiple parallel branches can be added according to actual circuit requirements, and the transistors in the parallel branches are evenly distributed on the power tube to detect the temperature of the power tube; in each parallel branch, one end of the current source IDC is connected to the power input terminal VCC, the other end of the current source IDC is connected to one end of the inverter INV and the collector of the transistor, the base of the transistor is connected to the positive end of the voltage source VDC, the emitter of the transistor is grounded, and the other end of the reflector is connected to the input end of the OR gate OR.

[0021] A protection circuit to prevent the load switch from being burned out by heat, such as Figure 3 As shown: A temperature sensor is fixed at the center point and four corners of the power tube to detect the center temperature of the power tube and the temperature of the four corners respectively; Figure 2 The chip of the circuit shown has many monitoring points for detecting temperature, which can more effectively and timely monitor the temperature of each point inside the power tube. Since the selected temperature sensor has a negative temperature coefficient, when the temperature of the power tube rises, the resistance value of the temperature sensor itself decreases, and the voltage value of the collector of the temperature sensor decreases. After being inverted by the inverter, the changes of several temperature sensors placed in the chip are ORed through the OR gate. If the temperature of any monitoring point is higher than the set temperature threshold, the OR gate outputs a high potential and transmits a signal to shut down the chip in time, thereby protecting the chip in time.

[0022] In summary, the present invention proposes a protection circuit for preventing a load switch from being burned by heat. The circuit is simple to implement and can accurately detect the temperature change of the power tube inside the chip in real time, thereby effectively preventing the load switch from being burned due to excessive temperature.

Claims

1. A protection circuit for preventing a load switch from being burned by heat, characterized in that: The protection circuit for preventing the load switch from being burned by heat comprises an input terminal VCC, a voltage source VDC, current sources IDC1, IDC2, IDC3, transistors Q1, Q2, Q3 with negative temperature coefficients, inverters INV1, INV2, INV3, an OR gate OR and an output terminal VOUT; The input terminal VCC is connected to one end of the current source IDC1, one end of the current source IDC2 and one end of the current source IDC3; the other end of the current source IDC1 is connected to one end of the inverter INV1 and the collector of the transistor Q1; the other end of the current source IDC2 is connected to one end of the inverter INV2 and the collector of the transistor Q2; the other end of the current source IDC3 is connected to one end of the inverter INV3 and the collector of the transistor Q3; the voltage source VDC is the regulator voltage, and the positive end of the voltage source VDC is connected to the transistors Q1 and Q2. , the base of Q3, and the negative terminal of the voltage source VDC are grounded; the base of the transistor Q1 is connected to the positive terminal of the voltage source VDC, the collector is connected to the other end of the current source IDC1 and one end of the inverter INV1, and the emitter is grounded; the base of the transistor Q2 is connected to the positive terminal of the voltage source VDC, the collector is connected to the other end of the current source IDC2 and one end of the inverter INV2, and the emitter is grounded; the base of the transistor Q3 is connected to the positive terminal of the voltage source VDC, the collector is connected to the other end of the current source IDC3 and one end of the inverter INV3, and the emitter is grounded; One end of the inverter INV1 is connected to the other end of the current source IDC1 and the collector of the transistor Q1, and the other end is connected to the input end of the OR gate OR; one end of the inverter INV2 is connected to the other end of the current source IDC2 and the collector of the transistor Q2, and the other end is connected to the input end of the OR gate OR; one end of the inverter INV3 is connected to the other end of the current source IDC3 and the collector of the transistor Q3, and the other end is connected to the input end of the OR gate OR; the input end of the OR gate OR is respectively connected to the other end of the inverter INV1, the other end of INV2 and the other end of INV3, and the output end of the OR gate OR is connected to the output port VOUT of the over-temperature protection circuit.

2. A protection circuit for preventing a load switch from being burned out by heat according to claim 1, characterized in that: Transistors Q1, Q2 and Q3 act as temperature sensors. Multiple parallel branches can be added according to actual circuit requirements, and the transistors in the parallel branches are evenly distributed on the power tube to detect the temperature of the power tube; in each parallel branch, one end of the current source IDC is connected to the power input terminal VCC, the other end of the current source IDC is connected to one end of the inverter INV and the collector of the transistor, the base of the transistor is connected to the positive terminal of the voltage source VDC, the emitter of the transistor is grounded, and the other end of the reflector is connected to the input terminal of the OR gate OR.

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