Power supply chip with load impedance detection protection and power supply

Abstract

The invention discloses a power supply chip with load impedance detection protection and a power supply. The power supply chip with the load impedance detection protection function comprises a DCDC power supply function module, a constant current source module, a load impedance detection circuit and a logic control circuit, during each power-on, the constant current source module outputs a constant current to supply power to load impedance detection, the load impedance detection circuit collects the voltage of the power supply output end to carry out load impedance detection, and the logic control circuit carries out logic control. The logic control circuit controls the DCDC power supply function module to be started or closed according to a load impedance detection result, and the power supply chip starts the DCDC power supply function module to start working only when it is confirmed that no short circuit exists at the load end through load impedance detection. The problem that the load is short-circuited and ignited or is overheated and burnt due to direct electrification when the load is short-circuited is avoided, and the technical effect of protecting the power supply chip and the load when the load is short-circuited is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply design, and particularly to a power supply chip and a power supply with load impedance detection and protection. Background Art

[0002] At present, some DCDC power supply chips on the market have overcurrent protection or over-temperature protection functions. In actual applications, various situations such as soldering short circuits, wiring short circuits at the load end, or internal short circuits caused by ESD (Electro-Static discharge) damage inside the load device often occur. In such situations, the overcurrent protection or over-temperature protection function of the DC / DC power supply chip can protect the power supply chip itself from being burned. However, usually, the threshold for triggering overcurrent protection requires a current of several amperes to be satisfied, which cannot ensure effective protection of the load device when a short circuit occurs, and there is a risk of directly burning the load.

[0003] Therefore, the existing overcurrent protection method of DCDC power supply chips can only protect the power supply chip itself when a short circuit occurs at the load, but cannot protect the load. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a power supply chip and a power supply with load impedance detection and protection, which can protect both the power supply chip and the load when a short circuit occurs at the load.

[0005] On the one hand, the present invention provides a power supply chip with load impedance detection and protection, including a power input terminal, a power output terminal, and a chip enable input terminal. The power supply chip with load impedance detection and protection further includes: a DCDC power function module for stabilizing the voltage input from the power input terminal and outputting a stable voltage to the power output terminal; a constant current source module, whose input terminal is connected to the power input terminal through a switching tube, and whose output terminal outputs a constant current to the power output terminal; a load impedance detection circuit for collecting the voltage at the power output terminal and outputting a corresponding feedback control signal according to the comparison result between the collected voltage and a reference voltage; a logic control circuit for controlling the start or stop of the DCDC power function module according to the feedback control signal, and for controlling the opening or closing of the switching tube according to the feedback control signal.

[0006] Preferably, the switching tube is a PMOS tube, and the output terminal of the logic control circuit is connected to the gate of the PMOS tube.

[0007] Preferably, the logic control circuit includes an AND gate, a NOT gate, and an OR gate. One input terminal of the AND gate is connected to the output terminal of the load impedance detection circuit, and the other input terminal of the AND gate is connected to the chip enable input terminal. The output terminal of the AND gate is respectively connected to the enable input terminal of the DCDC power supply function module and one input terminal of the OR gate. The input terminal of the NOT gate is connected to the chip enable input terminal, and the output terminal of the NOT gate is connected to the other input terminal of the OR gate. The output terminal of the OR gate is connected to the gate of the PMOS transistor.

[0008] Preferably, the load impedance detection circuit includes a comparator and a variable resistor R1. One fixed terminal of the variable resistor R1 is connected to the power input terminal, and the other fixed terminal of the variable resistor R1 is grounded. The positive input terminal of the comparator is connected to the power output terminal, the negative input terminal of the comparator is connected to the movable terminal of the variable resistor R1, and the output terminal of the comparator is connected to one input terminal of the AND gate.

[0009] On the other hand, the present invention provides a power supply, which includes the above-mentioned power supply chip with load impedance detection and protection.

[0010] When the above-mentioned power supply chip with load impedance detection and protection and the power supply are powered on each time, the load impedance is detected first, and the start or shutdown of the DCDC power supply function module inside the power supply chip is controlled according to the load impedance detection result. When it is confirmed through the load impedance detection that there is no short circuit at the load end, the power supply chip starts the DCDC power supply function module to start working, avoiding the problems of load short circuit and fire or load overheating and burnout caused by directly powering on when the load is short-circuited, and achieving the technical effect of protecting both the power supply chip and the load when the load has a short circuit. Description of the Drawings

[0011] Figure 1 It is a schematic circuit diagram of the power supply chip with load impedance detection and protection in an embodiment of the present invention. Detailed Embodiments

[0012] To make those of ordinary skill in the art understand the purpose, technical solution, and advantages of the present invention more clearly, the present invention will be further described below with reference to the drawings and embodiments.

[0013] The present invention provides a power chip with load impedance detection and protection, which includes a DCDC power function module, a constant current source module, a load impedance detection circuit, and a logic control circuit. Among them, the DCDC power function module is used to stabilize the voltage input from the power input terminal (Vin terminal) and output a stable voltage to the power output terminal (Vout terminal); the input terminal of the constant current source module is connected to the power input terminal through a switching transistor, and its output terminal outputs a constant current to the power output terminal to supply power for load impedance detection. The current output by the constant current source module should be small enough, such as 1 mA or 0.5 mA, to avoid burning the load when the load is short-circuited; the load impedance detection circuit is used to collect the voltage at the power output terminal and output a corresponding feedback control signal according to the comparison result between the collected voltage and the reference voltage; the logic control circuit is used to control the start or stop of the DCDC power function module according to the feedback control signal, and to control the opening or closing of the switching transistor according to the feedback control signal. The power chip with load impedance detection and protection of the present invention first performs load impedance detection each time it is powered on, and controls the start or stop of the DCDC power function module inside the power chip according to the load impedance detection result. When it is confirmed through load impedance detection that there is no short circuit at the load terminal, the power chip starts the DCDC power function module to start working, avoiding the problems of load short-circuit fire or load overheating and burning caused by directly powering on when the load is short-circuited, and achieving the technical effect of protecting both the power chip and the load when the load has a short circuit.

[0014] As Figure 1 shown, in an embodiment of the present invention, the switching transistor is a PMOS transistor, and the output terminal of the logic control circuit is connected to the gate of the PMOS transistor. Of course, in other embodiments of the present invention, the switching transistor can also be an NMOS transistor or other types of switching transistors.

[0015] In this embodiment, the logic control circuit includes an AND gate, a NOT gate, and an OR gate. One input terminal of the AND gate is connected to the output terminal of the load impedance detection circuit, and the other input terminal of the AND gate is connected to the chip enable input terminal (Enable terminal). The output terminal of the AND gate is respectively connected to the enable input terminal of the DCDC power function module and one input terminal of the OR gate. The input terminal of the NOT gate is connected to the chip enable input terminal, and the output terminal of the NOT gate is connected to the other input terminal of the OR gate. The output terminal of the OR gate is connected to the gate of the PMOS transistor. Of course, in other embodiments of the present invention, the logic control circuit can also select different logic devices and connect them in different ways to achieve the same circuit function as the logic control circuit in this embodiment.

[0016] In this embodiment, the load impedance detection circuit includes a comparator and a variable resistor R1. One fixed terminal of the variable resistor R1 is connected to the power input terminal, and the other fixed terminal of the variable resistor R1 is grounded. The positive input terminal of the comparator is connected to the power output terminal, the negative input terminal of the comparator is connected to the movable terminal of the variable resistor R1, and the output terminal of the comparator is connected to one input terminal of the AND gate. The output of the comparator is the feedback control signal. The variable resistor R1 is used for voltage division. By adjusting the movable terminal of the variable resistor R1, a reference level can be set to provide a reference level for the comparator as the threshold for judging load short circuit. The comparator is used for level comparison to judge whether the load is short-circuited by comparing the voltage at the power output terminal (Vout terminal) and the reference voltage. Of course, in other embodiments of the present invention, multiple series resistors can also be used to replace the variable resistor R1 to achieve the voltage division function and provide a reference level for the comparator.

[0017] The working principle of the power supply chip with load impedance detection and protection in this embodiment is as follows:

[0018] After the power supply chip is powered on at the Vin terminal, the DCDC power function module is not started. When the Enable signal is pulled high, the output of the AND gate (AND logic) is low, and the output of the OR gate (OR logic) is low. At this time, the PMOS is turned on, and the constant current source module starts to work, stably outputting a 1 mA current. At this time, there will be a 1 mA output at the Vout terminal, and the load connected to the Vout terminal of the power supply chip will form a certain voltage drop, which is the voltage on the feedback voltage line. When the feedback voltage is greater than the input level at the negative input terminal of the comparator, it is determined that the load impedance is normal; when the feedback voltage is less than the input level at the negative input terminal of the comparator, it is determined that the load impedance is too low (indicating a load short circuit). When it is determined that the load impedance is normal, the comparator outputs a high level, the AND gate outputs a high level, the DCDC power function module is turned on, and the power supply officially starts to work; the OR gate outputs a high level, the PMOS is turned off, and the constant current module stops working. When it is determined that the load impedance is too low, the comparator outputs a low level, the AND gate outputs a low level, the DCDC power function module remains off, the OR gate outputs a low level, and the PMOS and the constant current module remain working to continue detecting the load impedance until the load impedance is normal.

[0019] The present invention also provides a power supply, which includes the above-mentioned power supply chip with load impedance detection and protection. The power supply of the present invention includes a power supply chip with load impedance detection and protection. Each time when power is applied, load impedance detection is first performed, and according to the load impedance detection result, the DCDC power function module inside the power supply chip is controlled to start or stop. When it is confirmed through load impedance detection that there is no short circuit at the load end, the power supply chip starts the DCDC power function module to start working, avoiding the problems of load short circuit and ignition or load overheating and burning caused by directly applying power when there is a load short circuit, and achieving the technical effect of protecting both the power supply chip and the load when there is a load short circuit.

[0020] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Those skilled in the art can make various equivalent changes and improvements based on the above embodiments. Any equivalent changes or modifications made within the scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A power supply chip with load impedance detection and protection, comprising a power input terminal, a power output terminal, and a chip enable input terminal, characterized in that, Comprising: A DCDC power function module for regulating the voltage input from the power input terminal and outputting a stable voltage to the power output terminal; A constant current source module, whose input terminal is connected to the power input terminal through a switching transistor, and whose output terminal outputs a constant current to the power output terminal; A load impedance detection circuit for collecting the voltage at the power output terminal and outputting a corresponding feedback control signal according to the comparison result between the collected voltage and a reference voltage; A logic control circuit for controlling the startup or shutdown of the DCDC power function module according to the feedback control signal, and for controlling the opening or closing of the switching transistor according to the feedback control signal.

2. The power supply chip with load impedance detection and protection as described in claim 1, characterized in that, The switching transistor is a PMOS transistor, and the output terminal of the logic control circuit is connected to the gate of the PMOS transistor.

3. The power supply chip with load impedance detection and protection according to claim 2, wherein The logic control circuit includes an AND gate, a NOT gate, and an OR gate. One input terminal of the AND gate is connected to the output terminal of the load impedance detection circuit, and the other input terminal of the AND gate is connected to the chip enable input terminal. The output terminal of the AND gate is respectively connected to the enable input terminal of the DCDC power function module and one input terminal of the OR gate. The input terminal of the NOT gate is connected to the chip enable input terminal, and the output terminal of the NOT gate is connected to the other input terminal of the OR gate. The output terminal of the OR gate is connected to the gate of the PMOS transistor.

4. The power supply chip with load impedance detection and protection as described in claim 3, characterized in that, The load impedance detection circuit includes a comparator and a variable resistor R1. One fixed terminal of the variable resistor R1 is connected to the power input terminal, the other fixed terminal of the variable resistor R1 is grounded, the positive input terminal of the comparator is connected to the power output terminal, the negative input terminal of the comparator is connected to the movable terminal of the variable resistor R1, and the output terminal of the comparator is connected to one input terminal of the AND gate.

5. A power supply, characterized in that, The power supply includes a power supply chip with load impedance detection protection as described in any one of claims 1-4.

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