A DC power supply programmable overvoltage protection, undervoltage protection, and current limiting circuit

Abstract

This invention discloses a programmable overvoltage protection, undervoltage protection, and current limiting circuit for a DC power supply. It includes at least one DC power supply protection unit, with all protection units connected in parallel at their input and output. The parallel connection of multiple protection units enhances overcurrent capability. Each protection unit comprises a first digital potentiometer, a second digital potentiometer, a third digital potentiometer, and a power supply protection controller. The controller includes an overvoltage comparator, an undervoltage comparator, and an overcurrent operational amplifier. The resistance value of the digital potentiometers is set via a low-speed serial bus, thereby enabling programmable input power supply overvoltage threshold, undervoltage threshold, and current limiting value. This improves the versatility, integration, and reliability of the protection circuit, as well as its current breaking capacity and response speed.

Description

Technical Field

[0001] This invention belongs to the field of electronic engineering technology, specifically relating to a programmable overvoltage protection, undervoltage protection, and current limiting circuit for a DC power supply. Background Technology

[0002] During the testing and use of electronic products, operational errors, electrical assembly mistakes, power supply and load aging and drift may cause the power supply output voltage to exceed or fall below the threshold value, or the output current to exceed the maximum current of the electronic product, resulting in damage to the test equipment or electronic equipment, causing economic losses and personal injury.

[0003] Existing technical solutions are based on the operating power supply voltage range of electronic products, designing overvoltage and undervoltage protection, and selecting fuses according to the maximum current. The advantage is circuit simplicity, but the disadvantages are:

[0004] 1. Different electronic products have different operating power supply voltage ranges and operating currents, so overvoltage protection circuits, undervoltage protection circuits, and current limiting circuits that are not designed for electronic products have poor versatility.

[0005] 2. Using discrete components to implement circuit protection results in low integration, low reliability, and complex design.

[0006] 3. Ordinary fuses have weak current breaking capacity and slow response speed. Summary of the Invention

[0007] To overcome the shortcomings of existing technologies, this invention provides a programmable overvoltage protection, undervoltage protection, and current limiting circuit for a DC power supply. It includes at least one DC power supply protection unit, with all DC power supply protection units connected in parallel at their input and output. The parallel connection of multiple DC power supply protection units enhances overcurrent capability. Each DC power supply protection unit includes a first digital potentiometer, a second digital potentiometer, a third digital potentiometer, and a power supply protection controller. The power supply protection controller includes an overvoltage comparator, an undervoltage comparator, and an overcurrent operational amplifier. The resistance value of the digital potentiometer is set via a low-speed serial bus, thereby enabling programmable input power supply overvoltage threshold level, undervoltage threshold level, and input power supply current limiting value. This improves the versatility, integration, and reliability of the protection circuit, as well as its current breaking capacity and response speed.

[0008] The technical solution adopted by this invention to solve its technical problem is as follows:

[0009] A DC power supply programmable overvoltage protection, undervoltage protection and current limiting circuit includes at least one DC power supply protection unit, wherein each DC power supply protection unit is connected in parallel in the circuit, with the same power input and the same power output;

[0010] The DC power supply protection unit includes a first digital potentiometer, a second digital potentiometer, a third digital potentiometer, a first resistor, a second resistor, and a power supply protection controller; the power supply protection controller includes an overvoltage comparator, an undervoltage comparator, and an overcurrent operational amplifier;

[0011] One end of the first resistor is connected to the power input, and the other end is connected to the first digital potentiometer. The first digital potentiometer is equipped with a low-speed serial bus interface. The resistance value of the first digital potentiometer is set through the low-speed serial bus. After voltage division, an overvoltage acquisition signal is generated between the first resistor and the first digital potentiometer. The output power supply is controlled to be turned on or off by a voltage comparator.

[0012] One end of the second resistor is connected to the power input, and the other end is connected to the second digital potentiometer. The second digital potentiometer is equipped with a low-speed serial bus interface. The resistance value of the second digital potentiometer is set through the low-speed serial bus. After voltage division, an undervoltage acquisition signal is generated between the second resistor and the second digital potentiometer. The undervoltage comparator controls the on / off of the output power supply.

[0013] The third digital potentiometer is equipped with a low-speed serial bus interface. The resistance value of the third digital potentiometer is set through the low-speed serial bus, and the current acquisition signal is output by the third digital potentiometer. The output power supply current is limited by the current operational amplifier.

[0014] Preferably, the low-speed serial bus interface is an I2C interface or an SPI interface.

[0015] Preferably, the power protection controller is an electronic fuse.

[0016] Preferably, the power protection controller is model TPS26631RGER.

[0017] Preferably, the number of DC power supply protection units is determined based on the total overcurrent capacity requirement and the overcurrent capacity of a single DC power supply protection unit.

[0018] The beneficial effects of this invention are as follows:

[0019] 1. This invention has high versatility;

[0020] 2. The power protection controller of this invention uses a highly integrated electronic fuse, which makes the entire protection circuit highly integrated and reliable, while simplifying the design.

[0021] 3. The current breaking capacity of the electronic fuse of the present invention is within 10% of the set value, which is superior to that of ordinary fuses. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the DC power supply overvoltage protection, undervoltage protection, and current limiting circuit of the present invention.

[0023] Figure 2 This is a schematic diagram of the DC power supply protection unit of the present invention.

[0024] Figure 3 This is a circuit diagram of the DC power supply protection unit of the present invention.

[0025] Figure 4 This is a circuit diagram of the first digital potentiometer of the present invention.

[0026] Figure 5 This is a circuit diagram of the second digital potentiometer of the present invention.

[0027] Figure 6 This is a circuit diagram of the third digital potentiometer of the present invention. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0029] This invention calculates the resistance value of a first digital potentiometer based on the input power supply overvoltage threshold level, the resistance value of a first resistor, and the overvoltage comparison level inside the electronic fuse. The resistance value of the first digital potentiometer is configured via an I2C interface, thus enabling programmable input power supply overvoltage threshold. Similarly, it calculates the resistance value of a second digital potentiometer based on the input power supply undervoltage threshold level, the resistance value of a second resistor, and the undervoltage comparison level inside the electronic fuse. The resistance value of the second digital potentiometer is configured via an I2C interface, thus enabling programmable input power supply undervoltage threshold. Finally, it calculates the resistance value of a third digital potentiometer based on the maximum operating current and the overcurrent comparison level inside the electronic fuse. The resistance value of the third digital potentiometer is configured via an I2C interface, thus enabling programmable overcurrent threshold.

[0030] A DC power supply programmable overvoltage protection, undervoltage protection and current limiting circuit includes at least one DC power supply protection unit, wherein each DC power supply protection unit is connected in parallel in the circuit, with the same power input and the same power output;

[0031] The DC power supply protection unit includes a first digital potentiometer, a second digital potentiometer, a third digital potentiometer, a first resistor, a second resistor, and a power supply protection controller; the power supply protection controller includes an overvoltage comparator, an undervoltage comparator, and an overcurrent operational amplifier;

[0032] One end of the first resistor is connected to the power input, and the other end is connected to the first digital potentiometer. The first digital potentiometer is equipped with a low-speed serial bus interface. The resistance value of the first digital potentiometer is set through the low-speed serial bus. After voltage division, an overvoltage acquisition signal is generated between the first resistor and the first digital potentiometer. The output power supply is controlled to be turned on or off by a voltage comparator.

[0033] One end of the second resistor is connected to the power input, and the other end is connected to the second digital potentiometer. The second digital potentiometer is equipped with a low-speed serial bus interface. The resistance value of the second digital potentiometer is set through the low-speed serial bus. After voltage division, an undervoltage acquisition signal is generated between the second resistor and the second digital potentiometer. The undervoltage comparator controls the on / off of the output power supply.

[0034] The third digital potentiometer is equipped with a low-speed serial bus interface. The resistance value of the third digital potentiometer is set through the low-speed serial bus, and the current acquisition signal is output by the third digital potentiometer. The output power supply current is limited by the current operational amplifier. Specific implementation examples:

[0036] like Figure 1 As shown, a DC power supply programmable overvoltage protection, undervoltage protection and current limiting circuit includes at least one DC power supply protection unit, with the power inputs of all DC power supply protection units connected in parallel and the power outputs connected in parallel.

[0037] In this embodiment, the total overcurrent capacity is programmable from 0.6 amps to 18 amps, the overvoltage threshold level is programmable from 5V to 60V, and the undervoltage threshold level is programmable from 4.5V to 59V; the overcurrent capacity allocated to each DC power supply protection unit is programmable from 0.2 amps to 6 amps.

[0038] In this embodiment, the three DC protection units are designed identically, so one of them will be used as an example for explanation.

[0039] like Figure 2 As shown, the DC power supply protection unit includes a first digital potentiometer, a second digital potentiometer, a third digital potentiometer, a first resistor, a second resistor, and a power supply protection controller; the power supply protection controller includes an overvoltage comparator, an undervoltage comparator, and an overcurrent operational amplifier.

[0040] like Figure 3 As shown, the power protection controller U101 selects an electronic fuse of model TPS26631RGER, with an operating voltage of 4.5V to 60V, a single-chip overcurrent capability of 6A (error ±7%), overvoltage monitoring accuracy of ±2%, undervoltage monitoring accuracy of ±2%, an overvoltage comparator comparison voltage of 1.2V, and an undervoltage comparator comparison voltage of 1.2V.

[0041] In the diagram, PS_UV is the overvoltage acquisition signal generated by the first digital potentiometer voltage divider; PS_OV is the undervoltage acquisition signal generated by the second digital potentiometer voltage divider; PS_ILIM is the current acquisition signal generated by the third digital potentiometer; PS_IN is the power input; PS_OUT is the power output; SHDN is the shutdown control signal, active low, controlled by a microcontroller, DSP, or FPGA; R101 is a 4.7 kΩ pull-down resistor, used when the POWER GOOD function is not used; R103 is a 4.7 kΩ pull-down resistor, set to automatically retry every 648 milliseconds after overcurrent shutdown; capacitor C101 is the output surge current setting capacitor, selected as a 47 nF capacitor with a withstand voltage greater than 7 V.

[0042] like Figure 4 As shown, the first digital potentiometer U201 is an AD5272BCPZ-100-RL7 potentiometer with an I2C interface. The ADDR pin pull-high corresponds to the 7-bit I2C address 0x2C. The I2C interface is used to set the resistance value of the first digital potentiometer U201, and to generate an overvoltage acquisition signal PS_OV through voltage division. This signal is compared with 1.2V by the internal overvoltage comparator of the electronic fuse U101 to control the on / off state of the output power supply. The first resistor R202 is an RMK2012MB274FMT, 0805 package, with a resistance of 270 kΩ. The I2C bus signal is pulled up to 3.3V via 4.7 kΩ resistors R203 and R204.

[0043] The relationship between the overvoltage threshold level and the resistance value of the first digital potentiometer is as follows:

[0044]

[0045] In the formula:

[0046] R OV Program the resistance value for the first potentiometer;

[0047] U ULIM This is the overvoltage threshold level for the input power supply.

[0048] It can be seen that if the overvoltage threshold level is 5V, the first potentiometer programming resistance value needs to be set to 85.3 kΩ via the I2C interface; if the overvoltage threshold level is 60V, the first potentiometer programming resistance value needs to be set to 5.5 kΩ via the I2C interface.

[0049] like Figure 5As shown, the second digital potentiometer U301 is an AD5272BCPZ-100-RL7 potentiometer with an I2C interface. The floating ADDR pin corresponds to the 7-bit I2C address 0x2E. The I2C interface is used to set the resistance value of the second digital potentiometer U301, and to generate an undervoltage acquisition signal PS_UV through voltage division. This signal is compared with 1.2V by the undervoltage comparator inside the electronic fuse U101 to control the on / off state of the output power supply. The second resistor is an RMK2012MB274FMT, packaged in 0805, with a resistance of 270 kΩ.

[0050] The relationship between the undervoltage threshold level and the resistance value of the second digital potentiometer is as follows:

[0051]

[0052] In the formula:

[0053] R UV Program the resistance value for the second potentiometer;

[0054] U LLIM This is the undervoltage threshold level for the input power supply.

[0055] It can be seen that if the undervoltage threshold level is 4.5V, the second potentiometer needs to be programmed to a resistance of 98.2 kΩ via the I2C interface; if the undervoltage threshold level is 59V, the second potentiometer needs to be programmed to a resistance of 5.6 kΩ via the I2C interface.

[0056] like Figure 6 As shown, the third digital potentiometer U401 is an AD5272BCPZ-100-RL7 potentiometer with an I2C interface. Pulling the ADDR pin low corresponds to the 7-bit I2C address 0x2F. The I2C interface is used to set the resistance value of the third digital potentiometer U401 and generate a current acquisition signal PS_ILIM, which limits the power supply output current via the internal overcurrent operational amplifier of the electronic fuse U101. According to the formula, a current limit of 0.2 amps corresponds to a resistance of 90.0 kΩ, and a current limit of 6 amps corresponds to a resistance of 3 kΩ.

[0057] The relationship between the current limiting value and the resistance value of the third potentiometer is as follows:

[0058]

[0059] In the formula:

[0060] R (ILIM) The resistance value of the third potentiometer is in kiloohms.

[0061] I OL This is the current-limiting resistor value, in amperes.

[0062] It can be seen that if the current limiting value of a single DC power supply protection unit is 0.2 amps, then the programming resistance of the second potentiometer needs to be set to 90.0 kΩ via the I2C interface; if the current limiting value of a single DC power supply protection unit is 6 amps, then the programming resistance of the second potentiometer needs to be set to 3.0 kΩ via the I2C interface.

[0063] Based on the required input power overvoltage threshold level, input power undervoltage threshold level, and power current limit value, the resistance values ​​of the first digital potentiometer U201, the second digital potentiometer U301, and the third digital potentiometer U401 are calculated using the three formulas in the embodiment. Then, the resistance values ​​of the three digital potentiometers are configured through the I2C interface to complete the configuration of the programmable overvoltage protection, undervoltage protection, and current limiting circuit of the power supply.

[0064] In the diagram, U101 is the electronic fuse; U201 is the first digital potentiometer; U301 is the second digital potentiometer; U401 is the third digital potentiometer; R202 is the first resistor; R302 is the second resistor; C201, C202, C301, C302, C401, and C402 are power supply decoupling capacitors; SDA and SCL are I2C signal lines; PS_IN is the power input; PS_OUT is the power output; PS_OV is the overvoltage acquisition signal; PS_UV is the undervoltage acquisition signal; and PS_ILIM is the current acquisition signal.

Claims

1. A programmable overvoltage protection, undervoltage protection, and current limiting circuit for a DC power supply, characterized in that, include: At least one DC power supply protection unit is provided, and all DC power supply protection units are connected in parallel in the circuit, with the same power input and the same power output. The DC power supply protection unit includes a first digital potentiometer, a second digital potentiometer, a third digital potentiometer, a first resistor, a second resistor, and a power supply protection controller; the power supply protection controller includes an overvoltage comparator, an undervoltage comparator, and an overcurrent operational amplifier; One end of the first resistor is connected to the power input, and the other end is connected to the first digital potentiometer. The first digital potentiometer is equipped with a low-speed serial bus interface. The resistance value of the first digital potentiometer is set through the low-speed serial bus. After voltage division, an overvoltage acquisition signal is generated between the first resistor and the first digital potentiometer. The output power supply is controlled to be turned on or off by a voltage comparator. One end of the second resistor is connected to the power input, and the other end is connected to the second digital potentiometer. The second digital potentiometer is equipped with a low-speed serial bus interface. The resistance value of the second digital potentiometer is set through the low-speed serial bus. After voltage division, an undervoltage acquisition signal is generated between the second resistor and the second digital potentiometer. The undervoltage comparator controls the on / off of the output power supply. The third digital potentiometer is equipped with a low-speed serial bus interface. The resistance value of the third digital potentiometer is set through the low-speed serial bus. The current acquisition signal is output by the third digital potentiometer and the output power current is limited by the current operational amplifier. The relationship between the input power supply overvoltage threshold level and the programming resistance value of the first digital potentiometer is as follows: ； in, The programming resistance value for the first digital potentiometer. This is the input power supply overvoltage threshold level; The relationship between the input power supply undervoltage threshold level and the programming resistance value of the second digital potentiometer is as follows: ； in, The programming resistance value for the second digital potentiometer. This is the input power supply undervoltage threshold level; The relationship between the power supply current limit value and the programming resistance value of the third digital potentiometer is as follows: ； in, The programming resistance value for the third digital potentiometer. This is the power supply current limit value; Based on the required input power overvoltage threshold level, input power undervoltage threshold level, and power current limiting value, calculate the programming resistance values ​​of the first, second, and third digital potentiometers. Then, configure the programming resistance values ​​of the three digital potentiometers through the I2C interface to complete the configuration of the programmable overvoltage protection, undervoltage protection, and current limiting circuit.

2. The DC power supply programmable overvoltage protection, undervoltage protection, and current limiting circuit according to claim 1, characterized in that, The low-speed serial bus interface is either an I2C interface or an SPI interface.

3. The DC power supply programmable overvoltage protection, undervoltage protection, and current limiting circuit according to claim 1, characterized in that, The power protection controller is an electronic fuse.

4. The DC power supply programmable overvoltage protection, undervoltage protection, and current limiting circuit according to claim 1, characterized in that, The power protection controller is model TPS26631RGER.

5. A DC power supply programmable overvoltage protection, undervoltage protection, and current limiting circuit according to claim 1, characterized in that, The number of DC power supply protection units is determined based on the total overcurrent capacity requirement and the overcurrent capacity of a single DC power supply protection unit.

Images