AC protection system and method for electronic detonator modules

Abstract

This invention provides an AC / DC protection system and method for an electronic detonator module, including a high-voltage transient suppression tube, a first current-limiting resistor, a second current-limiting resistor, and an electronic detonator chip. The electronic detonator chip integrates a voltage clamping unit and a rectifier bridge. The high-voltage transient suppression tube is connected between the first and second input terminals of the electronic detonator module. Both ends of the high-voltage transient suppression tube are connected to the left ends of the first and second current-limiting resistors, respectively. The right end of the first current-limiting resistor is connected to the first input pin of the electronic detonator chip. The right end of the second current-limiting resistor is connected to the second input pin of the electronic detonator chip. The input terminal of the rectifier bridge inside the electronic detonator chip is connected to the first and second input pins, and the output terminal is connected to the power supply and ground. The voltage clamping unit is connected between the power supply and ground, with its high end connected to the power supply and its low end connected to ground. The other end of the electronic detonator module is connected to the firing head.

Description

Technical Field

[0001] This invention relates to the field of AC / DC protection technology for electronic detonator modules, specifically to an AC / DC protection system and method for electronic detonator modules. Background Technology

[0002] There are three main standard documents related to digital electronic detonators: "Safety Technical Requirements for Electronic Control Modules of Electronic Detonators," "WJT 9107-2025 Industrial Electronic Detonator Electronic Ignition Module," and "WJ9085-2024 Industrial Digital Electronic Detonators." All of these standards include test requirements for AC / DC safety protection, specifically divided into three items: applying 220V AC voltage for 10 seconds; applying 48V DC voltage for 10 seconds; and applying a 2kV DC voltage pulse. In all three tests, the module or detonator should not ignite.

[0003] As safety requirements for electronic detonators become increasingly stringent, the latest standards have raised the bar for the 220V AC test and the 2kV DC pulse test among the three tests mentioned above. Specifically: For the 10-second energization test of 220V AC voltage, the traditional test method allowed a 100ohm / 2W resistor to be connected in series on the test line, but the new standard no longer allows this resistor to be connected in series.

[0004] For the 2kV DC high-voltage pulse test, the internal capacitance of the detonator used to generate the high-voltage pulse was increased from 20μF to 200μF, and the equivalent energy was increased by 10 times.

[0005] With the improvement of standards, traditional modular design methods are no longer applicable. In traditional modular designs, a low-voltage transient voltage suppressor (TVS) is usually placed at the front end of the module, with an operating voltage typically in the range of 24V to 40V. During 220V AC testing, this TVS forms a complete circuit with the power supply path. The 100ohm / 2W resistor connected in series on the circuit burns out first due to excessive current, acting like a fuse. Therefore, neither the electronic detonator module nor the finished electronic detonator will catch fire or explode.

[0006] However, with the adoption of the new standard, the 100ohm / 2W resistor is no longer connected in series on the circuit. At this point, the low-voltage TVS on the module will burn out due to excessive current, creating a short circuit—the failure mode of TVS overheating and burning out is almost always a short circuit. Electronic detonator modules produce open flames, and for finished electronic detonators, if there is residual detonating material on the inner wall of the detonator casing during production, it will most likely directly detonate the detonator, posing an extremely high safety hazard.

[0007] To address the aforementioned 220V AC testing issue, one electronic detonator solution involves connecting a fuse in series with the TVS (Transient Voltage Suppressor) of the module. When 220V AC is applied, the fuse blows, protecting the module from ignition. However, this solution can cause the fuse to explode during 2kV high-voltage pulse testing, potentially even generating an open flame. The danger of this solution is further amplified by the new standard, which increases the energy of the 2kV high-voltage pulse by nearly tenfold.

[0008] The existing solutions mentioned above cannot simultaneously meet the safety requirements of 220V AC testing and 2kV DC pulse testing in the new standard, and there is an urgent need for a new modular solution to solve this problem.

[0009] Patent application CN113405416A discloses an intrinsically safe circuit and delay device for electronic detonators, which can eliminate potential safety hazards in coal mine operations and has a high safety factor. The intrinsically safe circuit includes the following electrically connected components: a current limiting module, whose input is connected to the detonator leads to limit the current; a transient suppression module, whose input is connected to the current limiting module's output to prevent surge pulses; a rectifier module, whose input is connected to the transient suppression module's output to convert AC to DC; a blocking module, whose input is connected to the rectifier module's output to prevent the energy storage module at the electronic detonator's control end from discharging to the detonator leads; and a transceiver auxiliary module, connected to the blocking module's output to clamp the output signal. However, this patent cannot completely solve the existing technical problems and does not meet the needs of this invention. Summary of the Invention

[0010] In view of the deficiencies in the prior art, the purpose of this invention is to provide an AC / DC protection system and method for an electronic detonator module.

[0011] The AC / DC protection system for the electronic detonator module provided by the present invention includes: a high-voltage transient suppression tube, a first current-limiting resistor, a second current-limiting resistor, and an electronic detonator chip; The electronic detonator chip integrates a voltage clamping unit and a rectifier bridge. The electronic detonator module includes a first input terminal and a second input terminal; The high-voltage transient suppression tube is connected across the first and second input terminals of the electronic detonator module. The two ends of the high-voltage transient suppression tube are respectively connected to the left end of the first current-limiting resistor and the left end of the second current-limiting resistor; The right end of the first current-limiting resistor is connected to the first input pin of the electronic detonator chip; The right end of the second current-limiting resistor is connected to the second input pin of the electronic detonator chip; The input terminal of the rectifier bridge inside the electronic detonator chip is connected to the first input pin and the second input pin, and the output terminal is connected to the power supply VDD and ground GND. The voltage clamping unit is connected between the power supply VDD and the ground GND, with its high end connected to VDD and its low end connected to GND. The other end of the electronic detonator module is connected to the firing head.

[0012] Preferably, it further includes a first electrostatic discharge (ESD) protection device and a second ESD protection device; The right end of the first current-limiting resistor is connected to the first input pin of the electronic detonator chip and the upper end of the first electrostatic discharge protection device; The right end of the second current-limiting resistor is connected to the second input pin of the electronic detonator chip and the lower end of the second electrostatic discharge protection device; The lower end of the first electrostatic discharge protection device is connected to the upper end of the second electrostatic discharge protection device, and they are both led to a metal spring. The metal shrapnel contacts the inner wall of the detonator casing in the electronic detonator; The high-voltage transient suppression tube constitutes the first level of protection, the first current-limiting resistor and the second current-limiting resistor constitute the second level of protection, and the first electrostatic discharge protection device and the second electrostatic discharge protection device connected in series constitute the third level of protection.

[0013] Preferably, it further includes a first discharge capacitor and a second discharge capacitor; The two ends of the high-voltage transient suppression tube are respectively connected to the upper end of the first discharge capacitor and the lower end of the second discharge capacitor; The right end of the first current-limiting resistor is connected to the first input pin of the electronic detonator chip and the upper end of the first discharge capacitor; The right end of the second current-limiting resistor is connected to the second input pin of the electronic detonator chip and the lower end of the second discharge capacitor; The lower end of the first bleeder capacitor is connected to the upper end of the second bleeder capacitor, and both are led to a metal spring. The metal shrapnel contacts the inner wall of the detonator casing in the electronic detonator; The high-voltage transient suppression tube constitutes the first level of protection, and the first current-limiting resistor, the second current-limiting resistor, and the internal protection unit of the electronic detonator chip work together to constitute the second level of protection.

[0014] Preferably, the package size of the high-voltage transient suppression tube is SOD123.

[0015] Preferably, the operating voltage of the high-voltage transient suppression tube is above 380V and not higher than 2kV.

[0016] Preferably, the resistance values ​​of both the first current-limiting resistor and the second current-limiting resistor are greater than or equal to 1 kΩ.

[0017] Preferably, the input withstand voltage of the first and second input pins of the electronic detonator chip exceeds 45V.

[0018] Preferably, the voltage clamping unit has a continuous current carrying capacity greater than 150mA.

[0019] The AC / DC protection method for an electronic detonator module provided by the present invention includes: When a 220V AC voltage is applied to the first input terminal and the second input terminal, the high-voltage transient suppression tube does not operate, and the current is connected by the first current-limiting resistor, the second current-limiting resistor and the voltage clamping unit inside the electronic detonator chip. When a 2kV DC high-voltage pulse is applied to the first input terminal and the second input terminal, the high-voltage transient suppression tube activates to absorb the pulse energy; When a 48V DC voltage is applied to the first input terminal and the second input terminal, the high-voltage transient suppression tube does not operate, and the first and second input pins of the electronic detonator chip form a voltage divider with the first current-limiting resistor and the second current-limiting resistor.

[0020] Preferably, when a 220V AC voltage is applied, the peak current of the circuit does not exceed 150mA.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention uses a specially customized high-voltage transient voltage suppression device (TVS) to replace the low-voltage TVS device on the traditional module. Combined with the high-voltage characteristics of the electronic detonator chip pins, the voltage clamping unit PowerClamp inside the chip, and the current limiting resistor on the module, the electronic detonator can safely not ignite under three safety protection tests: 220V AC for 10 seconds, 48V DC for 10 seconds, and 2kV DC pulse. (2) In the 220V AC test, since the high voltage TVS operating voltage is higher than the AC peak voltage, the TVS will not operate. The circuit current is limited to below 150mA by the current limiting resistor and the internal voltage clamping unit of the chip. There is no open flame or smoke in the module. In the 2kV DC pulse test, the high voltage TVS operates instantaneously to absorb the pulse energy. There is no open flame or smoke in the module. In the 48V DC test, the TVS does not operate. Relying on the high withstand voltage characteristics of the chip pins and the voltage division effect of the current limiting resistor, there is no open flame or smoke in the module. (3) The electronic detonator module using this protection system can be implemented without changing the existing design of the module, the device pins are compatible, no additional devices are needed, and only direct replacement is required, which only increases the cost slightly. At the same time, since the module design remains unchanged and the TVS that is replaced is only a protective device, most of the test items related to the module and the finished detonator do not need to be redone. Only the three related AC and DC test items mentioned above need to be focused on, which is economically efficient and the module is safer and more reliable. Attached Figure Description

[0022] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a diagram of the three-level protection structure of an electronic detonator module; Figure 2 This is a diagram of the two-stage protection structure of an electronic detonator module. Detailed Implementation

[0023] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0024] Example This invention provides an AC / DC protection system for an electronic detonator module, comprising a high-voltage transient suppression tube D1, a first current-limiting resistor R1, a second current-limiting resistor R2, a first electrostatic discharge (ESD) protection device D2, a second ESD protection device D3, and a high-voltage-resistant electronic detonator chip. Alternatively, the ESD protection device can be replaced with a capacitor discharge branch consisting of a first discharge capacitor C1 and a second discharge capacitor C2.

[0025] The core innovation of this invention lies in changing the traditional electronic detonator module design method. It replaces the low-voltage TVS device on the traditional module with a specially customized high-voltage transient suppression tube D1, and simultaneously employs an electronic detonator chip with an integrated voltage clamping unit (Power Clamp) to form a complete AC / DC protection system. This voltage clamping unit has a continuous current carrying capacity greater than 150mA.

[0026] The high-voltage transient suppressor diode D1 has the following characteristics: its operating voltage is at least 380V. Considering a certain design margin, it needs to be 1.2 times higher than the peak voltage of 220V AC voltage, i.e., 311V×1.2≈374V, while not exceeding 2kV. Furthermore, this device adopts the same package size SOD123 as the low-voltage TVS, maximizing power within a limited size.

[0027] The working mechanism of the protection system of the present invention is as follows: When a 220V AC voltage is applied to the line, D1 will not activate because the operating voltage of the high-voltage transient suppression transistor D1 is not reached. The current flows through the first current-limiting resistor R1, the second current-limiting resistor R2, and the voltage clamping unit (Power Clamp) in the rectified power supply path inside the electronic detonator chip, forming a complete circuit. When this voltage clamping unit activates, the total peak current does not exceed 150mA, calculated as 311V / 2kohm≈150mA, where the values ​​of R1 and R2 are generally greater than or equal to 1kohm. During a prolonged 10-second current flow, the current-limiting resistors of the electronic detonator module may be slightly damaged due to overload, increasing their resistance and further suppressing the circuit current. However, the module will not exhibit any signs of open flame or smoke, fully meeting all relevant standards for electronic detonators.

[0028] When performing a 2kV DC high-voltage pulse test, the high-voltage transient suppression diode D1 is designed to operate at approximately 380V. When the 2kV high-voltage pulse enters the electronic detonator module, D1 will activate instantaneously, completely absorbing the high-voltage pulse. Due to the size limitations of the electronic detonator module, D1 is packaged in an SOD123 package, limiting its power output. After the 2kV DC high-voltage pulse test, the D1 device will essentially be damaged into a short-circuit state, but the electronic detonator module will not show any signs of open flame or smoke, fully meeting all relevant standards and requirements for electronic detonators.

[0029] When a 48V DC 10-second test is performed, the high-voltage transient suppression tube D1 will not activate. The electronic detonator chip used in this system has an input withstand voltage of over 45V at its A and B pins. Combined with the voltage division effect of the first current-limiting resistor R1 and the second current-limiting resistor R2 on the module, the electronic detonator module will not show any signs of open flame or smoke after the 48V DC test, fully meeting all relevant standards and requirements for electronic detonators.

[0030] In summary, by replacing the traditional low-voltage TVS device with a high-voltage transient suppression transistor D1, and combining the high-voltage characteristics of the electronic detonator chip pins (greater than 45V), the voltage clamping unit Power Clamp with a current-carrying capacity greater than 150mA inside the chip, and the current-limiting resistor on the module, the electronic detonator can safely remain undisturbed under three tests: 220V AC for 10 seconds, 48V DC for 10 seconds, and 2kV DC pulse.

[0031] Based on the above core ideas, this invention provides two typical protective structure implementation schemes: Option 1: Adopt a three-level protection structure.

[0032] like Figure 1 As shown, the protection structure of this scheme is composed of three levels of protection mechanisms working together.

[0033] The first level of protection is provided by the high-voltage transient suppression tube D1 connected between the input interfaces A and B of the electronic detonator leads. When a surge or electrostatic high voltage from the electronic detonator leads intrudes, if the voltage reaches the operating voltage of D1 (around 380V), D1 will conduct instantaneously, clamping the voltage between lines A and B to a safe level, absorbing most of the surge energy, and achieving primary transient overvoltage protection.

[0034] The second level of protection is provided by the first current-limiting resistor R1 and the second current-limiting resistor R2. The two ends of the high-voltage transient suppression transistor D1 are connected to the left ends of the first current-limiting resistor R1 and the second current-limiting resistor R2, respectively. The right end of the first current-limiting resistor R1 is connected to pin A of the electronic detonator chip and the upper end of the second electrostatic discharge (ESD) device D2; the right end of the second current-limiting resistor R2 is connected to pin B of the electronic detonator chip and the lower end of the second ESD device D3. The current-limiting resistors R1 and R2 limit the residual voltage entering the subsequent stage, restricting the current amplitude flowing into the chip pins and subsequent discharge branches, thus acting as a buffer and energy attenuation mechanism. Simultaneously, in 220V AC testing, this current-limiting resistor, in conjunction with the chip's internal voltage clamping unit Power Clamp, forms a complete circuit, limiting the peak current to below 150mA.

[0035] The third level of protection is provided by an electrostatic discharge branch consisting of the first electrostatic discharge device D2 and the second electrostatic discharge device D3 connected in series. The lower end of the first electrostatic discharge device D2 is connected to the upper end of the second electrostatic discharge device D3, and they are both led to a metal spring. The residual surge or electrostatic energy, after being attenuated by the current-limiting resistor, is conducted to the metal spring through the discharge channel formed by D2 and D3. The metal spring contacts the inner wall of the detonator shell in the electronic detonator and is finally discharged to the ground through the shell. In addition, the electronic detonator chip also integrates a rectifier bridge function and a voltage clamping unit, Power Clamp. The input of the rectifier bridge is pins A and B, and the output is power supply VDD and ground GND. The voltage clamping unit, Power Clamp, is connected between power supply VDD and ground GND, with its high end connected to VDD and its low end connected to GND, providing further voltage clamping protection for the internal power domain of the chip. The other end of the electronic detonator module is connected to the firing head.

[0036] For this type of three-level protection structure module, simply replacing the original first-level low-voltage TVS with a high-voltage transient suppression tube D1 is sufficient to achieve the AC / DC protection function of this invention.

[0037] Option 2: Adopt a two-level protection structure.

[0038] like Figure 2 As shown, the protection structure of this scheme consists of two levels of protection mechanisms working together.

[0039] The first level of protection is provided by the high-voltage transient suppressor D1 connected between the input interfaces A and B of the electronic detonator pins. When a surge or electrostatic high voltage from the electronic detonator pins intrudes, if the voltage reaches approximately 380V, the operating voltage of D1, D1 will instantly conduct, clamping the voltage between lines A and B to a safe level. Simultaneously, the voltage is conducted to the ground through two high-voltage capacitors via the metal contact spring, achieving primary transient overvoltage protection and common-mode energy discharge. Specifically, the two ends of the high-voltage transient suppressor D1 are connected to the left ends of the first current-limiting resistor R1 and the second current-limiting resistor R2, respectively, and are also connected to the upper end of the first discharge capacitor C1 and the lower end of the second discharge capacitor C2, respectively.

[0040] The second level of protection is achieved collaboratively by the first current-limiting resistor R1, the second current-limiting resistor R2, and the internal protection unit of the chip. The right end of the first current-limiting resistor R1 is connected to pin A of the electronic detonator chip and the upper end of the first bleeder capacitor C1; the right end of the second current-limiting resistor R2 is connected to pin B of the electronic detonator chip and the lower end of the second bleeder capacitor C2. The lower end of the first bleeder capacitor C1 is connected to the upper end of the second bleeder capacitor C2, and both are led to a metal spring. This metal spring contacts the inner wall of the detonator casing within the electronic detonator, ultimately discharging the energy to the ground through the casing. The residual surge energy, initially absorbed by the first-stage D1 and bleeder capacitor, is further limited and attenuated by the current-limiting resistors R1 and R2, restricting the current amplitude entering the chip pins. The electronic detonator chip integrates a rectifier bridge, with inputs at pins A and B and outputs at power supply VDD and ground GND. A power clamp unit is connected between VDD and GND, with its high-side connected to VDD and its low-side connected to GND, providing final voltage clamping protection for the chip's internal power domain. In 220V AC testing, current-limiting resistors R1 and R2, together with the chip's internal power clamp unit, form a complete circuit, limiting the peak current to below 150mA. The other end of the electronic detonator module is connected to the ignition head.

[0041] For modules with this type of two-stage protection structure, the AC / DC protection function of the present invention can be achieved simply by replacing the original first-stage low-voltage TVS with the high-voltage transient suppression tube D1.

[0042] The protection system of this invention has the advantage of not requiring changes to the existing module design, ensuring pin compatibility, eliminating the need for additional components, and allowing for direct replacement with only a minimal increase in cost. Furthermore, since the module design remains unchanged, and the replaced TVS is merely a protective device, most tests related to the module and the finished detonator do not need to be repeated. Only the three AC / DC tests mentioned above need to be performed, resulting in high economic efficiency and a safer, more reliable module.

[0043] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0044] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. An AC / DC protection system for an electronic detonator module, characterized in that, include: High-voltage transient suppression tube, first current-limiting resistor, second current-limiting resistor, and electronic detonator chip; The electronic detonator chip integrates a voltage clamping unit and a rectifier bridge. The electronic detonator module includes a first input terminal and a second input terminal; The high-voltage transient suppression tube is connected across the first and second input terminals of the electronic detonator module. The two ends of the high-voltage transient suppression tube are respectively connected to the left end of the first current-limiting resistor and the left end of the second current-limiting resistor; The right end of the first current-limiting resistor is connected to the first input pin of the electronic detonator chip; The right end of the second current-limiting resistor is connected to the second input pin of the electronic detonator chip; The input terminal of the rectifier bridge inside the electronic detonator chip is connected to the first input pin and the second input pin, and the output terminal is connected to the power supply VDD and ground GND. The voltage clamping unit is connected between the power supply VDD and the ground GND, with its high end connected to VDD and its low end connected to GND. The other end of the electronic detonator module is connected to the firing head.

2. The AC / DC protection system of the electronic detonator module according to claim 1, characterized in that, It also includes a first electrostatic discharge (ESD) protection device and a second ESD protection device; The right end of the first current-limiting resistor is connected to the first input pin of the electronic detonator chip and the upper end of the first electrostatic discharge protection device; The right end of the second current-limiting resistor is connected to the second input pin of the electronic detonator chip and the lower end of the second electrostatic discharge protection device; The lower end of the first electrostatic discharge protection device is connected to the upper end of the second electrostatic discharge protection device, and they are both led to a metal spring. The metal shrapnel contacts the inner wall of the detonator casing in the electronic detonator; The high-voltage transient suppression tube constitutes the first level of protection, the first current-limiting resistor and the second current-limiting resistor constitute the second level of protection, and the first electrostatic discharge protection device and the second electrostatic discharge protection device connected in series constitute the third level of protection.

3. The AC / DC protection system of the electronic detonator module according to claim 1, characterized in that, It also includes a first bleeder capacitor and a second bleeder capacitor; The two ends of the high-voltage transient suppression tube are respectively connected to the upper end of the first discharge capacitor and the lower end of the second discharge capacitor; The right end of the first current-limiting resistor is connected to the first input pin of the electronic detonator chip and the upper end of the first discharge capacitor; The right end of the second current-limiting resistor is connected to the second input pin of the electronic detonator chip and the lower end of the second discharge capacitor; The lower end of the first bleeder capacitor is connected to the upper end of the second bleeder capacitor, and both are led to a metal spring. The metal shrapnel contacts the inner wall of the detonator casing in the electronic detonator; The high-voltage transient suppression tube constitutes the first level of protection, and the first current-limiting resistor, the second current-limiting resistor, and the internal protection unit of the electronic detonator chip work together to constitute the second level of protection.

4. The AC / DC protection system of the electronic detonator module according to claim 1, characterized in that, The package size of the high-voltage transient suppression tube is SOD123.

5. The AC / DC protection system of the electronic detonator module according to claim 1, characterized in that, The operating voltage of the high-voltage transient suppression tube is above 380V and not higher than 2kV.

6. The AC / DC protection system of the electronic detonator module according to claim 1, characterized in that, The resistance values ​​of both the first current-limiting resistor and the second current-limiting resistor are greater than or equal to 1 kΩ.

7. The AC / DC protection system of the electronic detonator module according to claim 1, characterized in that, The first and second input pins of the electronic detonator chip have an input withstand voltage exceeding 45V.

8. The AC / DC protection system of the electronic detonator module according to claim 1, characterized in that, The voltage clamping unit has a continuous current carrying capacity of more than 150mA.

9. A method for AC / DC protection of an electronic detonator module based on the system of any one of claims 1 to 8, characterized in that, include: When a 220V AC voltage is applied to the first input terminal and the second input terminal, the high-voltage transient suppression tube does not operate, and the current is connected by the first current-limiting resistor, the second current-limiting resistor and the voltage clamping unit inside the electronic detonator chip. When a 2kV DC high-voltage pulse is applied to the first input terminal and the second input terminal, the high-voltage transient suppression tube activates to absorb the pulse energy; When a 48V DC voltage is applied to the first input terminal and the second input terminal, the high-voltage transient suppression tube does not operate, and the first and second input pins of the electronic detonator chip form a voltage divider with the first current-limiting resistor and the second current-limiting resistor.

10. The AC / DC protection method for the electronic detonator module according to claim 9, characterized in that, When a 220V AC voltage is applied, the peak current of the circuit does not exceed 150mA.

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