CN210639607U - Reset signal filter circuit - Google Patents
Reset signal filter circuit Download PDFInfo
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- CN210639607U CN210639607U CN201922058754.3U CN201922058754U CN210639607U CN 210639607 U CN210639607 U CN 210639607U CN 201922058754 U CN201922058754 U CN 201922058754U CN 210639607 U CN210639607 U CN 210639607U
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- voltage monitoring
- monitoring chip
- resistor
- transient suppression
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Abstract
The utility model discloses a reset signal filter circuit relates to embedded system's hardware technical field for filter reset signal to MCU in embedded system, including voltage monitoring chip protection unit, high frequency signal filter unit, voltage monitoring chip and the reset signal filter unit who establishes ties in proper order, connect after establishing ties in proper order MCU. The utility model discloses can guarantee to monitor real power loss of electricity signal, can ensure the system operation reliably again general interference signal of filtering.
Description
[ technical field ] A method for producing a semiconductor device
The utility model relates to an embedded system's hardware technical field, concretely relates to reset signal filter circuit.
[ background of the invention ]
At present, besides the watchdog function of the MCU itself, an external reset chip is used for various embedded systems, especially those with high reliability requirements, and its main function is to monitor the voltage supplied to the MCU in real time, for example, the voltage is 3.3V when the normal operation is normal, and the threshold voltage is set at 2.8V, and if the voltage is lower than 2.8V, the reset chip immediately gives a reset signal to force the MCU to reset.
However, the reset circuit in the prior art monitors the power voltage in real time, and when the detected voltage is lower than the threshold voltage, the chip immediately outputs a signal to reset the chip even if the time is in ns level. The interference of system power supply can be the interference from the start and stop of power equipment, such as a fan, a water pump and the like, the time is generally in the ms level, and the interference belongs to the interference of a common power supply. When the system is reset, the parameters of the general RAM are all lost, so that the system reset can cause input and output detection to be completely closed, the equipment operation logic is very easy to be abnormal, and the equipment is easy to be damaged.
[ Utility model ] content
For solving the problem, the utility model provides a reset signal filter circuit can guarantee to monitor real power loss of electricity signal promptly, can filter general interference signal again, ensures that the system operation is reliable.
In order to achieve the above purpose, the utility model adopts the following technical scheme:
the utility model provides a reset signal filter circuit for filter reset signal to MCU in embedded system, reset signal filter circuit includes voltage monitoring chip protection unit, high frequency signal filter unit, voltage monitoring chip and reset signal filter unit, voltage monitoring chip protection unit, high frequency signal filter unit, voltage monitoring chip and reset signal filter unit connect after establishing ties in proper order MCU.
Optionally, the reset signal filtering unit includes a first bidirectional transient suppression diode, a resistor R1 and an electrolytic capacitor C1, the output end of the voltage monitoring chip is connected to one end of the first bidirectional transient suppression diode, the other end of the first bidirectional transient suppression diode is grounded, the anode of the electrolytic capacitor C1 is connected to the MCU, the cathode of the electrolytic capacitor C1 is grounded, and the resistor R1 is connected to the output end of the voltage monitoring chip and the anode of the electrolytic capacitor C1.
Optionally, the resistance of the resistor R1 is 20k Ω, and the capacitance of the electrolytic capacitor C1 is 10 μ F.
Optionally, the voltage monitoring chip protection unit includes a second bidirectional transient suppression diode, the operating voltage of the embedded system is input from one end of the second bidirectional transient suppression diode, and the other end of the second bidirectional transient suppression diode is grounded.
Optionally, the high-frequency signal filtering unit includes a resistor R2 and a capacitor C2, one end of the capacitor C2 is connected to the input terminal of the voltage monitoring chip, the other end of the capacitor C2 is grounded, one end of the resistor R2 is connected to one end of the operating voltage of the second bidirectional transient suppression diode input embedded system, and the other end of the resistor R2 is connected to the input terminal of the voltage monitoring chip.
Optionally, the resistance of the resistor R2 is 100 Ω, and the capacitance of the capacitor C2 is 0.1 μ F.
Optionally, the second bi-directional transient suppression diode filters interference voltage above 5V.
Optionally, the voltage monitoring chip outputs a low level signal to the reset signal filtering unit when the voltage received by the voltage monitoring chip is lower than 2.8V.
Optionally, the period of the low-level signal is 100 ms.
The utility model provides a method has following beneficial effect:
the utility model provides a reset signal filter circuit improves the reset circuit among the prior art. After improvement, the original real-time voltage monitoring function is kept, when microsecond-level interference pulses such as power grid voltage fluctuation, surge, motor start and stop and the like are received and interference signals which cannot cause MCU (microprogrammed control unit) dead halt or disorderly action are not generated, wrong reset signals caused by the interference signals can be filtered and eliminated in time, and a huge stabilizing effect is achieved on an embedded system.
These features and advantages of the present invention will be disclosed in more detail in the following detailed description and the accompanying drawings. The best mode or means of the present invention will be described in detail with reference to the accompanying drawings, but not limited thereto. In addition, the features, elements and components appearing in each of the following and in the drawings are plural and different symbols or numerals are labeled for convenience of representation, but all represent components of the same or similar construction or function.
[ description of the drawings ]
The present invention will be further explained with reference to the accompanying drawings:
fig. 1 is a circuit diagram of an embodiment of the present invention.
The device comprises a power supply, a voltage monitoring chip, a 1-MCU, a 2-voltage monitoring chip, a 3-reset signal filtering unit, a 4-voltage monitoring chip protecting unit and a 5-high-frequency signal filtering unit.
[ detailed description ] embodiments
The technical solutions of the embodiments of the present invention are explained and explained below with reference to the drawings of the embodiments of the present invention, but the embodiments described below are only preferred embodiments of the present invention, and not all embodiments. Based on the embodiments in the embodiment, other embodiments obtained by those skilled in the art without any creative work belong to the protection scope of the present invention.
Reference in the specification to "one embodiment" or "an example" means that a particular feature, structure or characteristic described in connection with the embodiment itself may be included in at least one embodiment of the patent disclosure. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment.
Examples
As shown in fig. 1, the present embodiment provides a reset signal filtering circuit for filtering an erroneous reset signal to the MCU1 in an embedded system. When the interference of power supply of the embedded system comes from power equipment, such as the interference of starting and stopping of a fan, a water pump and the like, the time is generally in the ms level, and the interference belongs to general power supply interference, but a reset circuit in the prior art still can send a reset signal to reset the MCU, so the sent reset signal is an error reset signal, general RAM parameters can be completely lost when the embedded system is reset, the reset of the embedded system can cause input, the output detection is completely closed, the abnormal operation logic of the equipment is easily caused, and the equipment is easily damaged. Therefore, such erroneous reset signals need to be filtered out. The reset signal filter circuit that this embodiment provided includes voltage monitoring chip protection unit 4, high frequency signal filter unit 5, voltage monitoring chip 2 and reset signal filter unit 3, and voltage monitoring chip protection unit 4, high frequency signal filter unit 5, voltage monitoring chip 2 and reset signal filter unit 3 connect MCU1 after establishing ties in proper order.
The reset signal filtering unit 3 comprises a first bi-directional transient suppression diode T1, a resistor R1 and an electrolytic capacitor C1, wherein the model of the first bi-directional transient suppression diode T1 is GBLC05, the resistance of the resistor R1 is 20k Ω, and the capacitance of the electrolytic capacitor C1 is 10 μ F. The output end of the voltage monitoring chip 2 is connected with one end of a first bidirectional transient suppression diode T1, the other end of the first bidirectional transient suppression diode T1 is grounded, the anode of an electrolytic capacitor C1 is connected with the MCU1, the cathode of the electrolytic capacitor C1 is grounded, and a resistor R1 is connected with the output end of the voltage monitoring chip 2 and the anode of the electrolytic capacitor C1. In other words, one end of the resistor R1 is connected to the common terminal of the voltage monitoring chip 3 and the first bi-directional transient suppression diode T1, and the other end of the resistor R1 is connected to the anode of the electrolytic capacitor C1 and the common terminal of the MCU 1.
The voltage monitoring chip protection unit 4 comprises a second bidirectional transient suppression diode T2, the operating voltage of the embedded system is input from one end of the second bidirectional transient suppression diode T2, and the other end of the second bidirectional transient suppression diode T2 is grounded. The model of the second bi-directional transient suppression diode T2 is GBLC05, and is used for filtering voltage interference above 5V to protect the voltage monitoring chip 2.
The high-frequency signal filtering unit 5 comprises a first-order filtering circuit formed by a resistor R2 and a capacitor C2, wherein the resistance value of the resistor R2 is 100 omega, and the capacitance value of the capacitor C2 is 0.1 muF. One end of the capacitor C2 is connected to the input end of the voltage monitoring chip 2, the other end of the capacitor C2 is grounded, one end of the resistor R2 is connected to one end of the second bidirectional transient suppression diode T2, at which the operating voltage of the embedded system is input, and the other end of the resistor R2 is connected to the input end of the voltage monitoring chip 2. In other words, one end of the resistor R2 is connected to the common terminal of the embedded system power supply and the second bi-directional transient suppression diode T2, and the other end of the resistor R2 is connected to the common terminal of the capacitor C2 and the voltage monitoring chip 2. The high frequency signal filtering unit 5 directly couples the high frequency signal to the ground terminal of the embedded system, which is equivalent to filtering the high frequency interference signal.
When the voltage received by the voltage monitoring chip 2 is lower than 2.8V, a low level signal is output to the reset signal filtering unit 3. The period of the low level signal is 100 ms.
In the reset signal filtering unit 3, if the time constant τ of the RC circuit formed by the resistor R1 and the electrolytic capacitor C1 is RC:
when charging, Uc is Ux [1-e (-t/tau) ], and U is the power supply voltage of the embedded system;
when discharging, Uc is Uo × e (-t/tau), and Uo is the voltage on the electrolytic capacitor C1 before discharging.
Time constant of RL circuit: τ is L/R;
in this embodiment, the requirement of the embedded system is satisfied when the voltage of 0.5V is the reset voltage of the MCU1, that is, when the low-level signal is surrounded by T equal to 100ms, Uc is less than 0.5, and the resistance R1 and the electrolytic capacitor C1 in the reset signal filtering unit 3 are calculated to be at least equal to 18K and 10uf, respectively. In order to make the reset signal filtering unit 3 have a margin, the resistance R1 is 20k, and the electrolytic capacitor C1 is 10 uf.
When the interference of embedded system power supply comes from the interference of starting and stopping of power equipment, such as a fan, a water pump and the like, the time is generally in the ms level, and the interference belongs to a common power supply, so that a reset signal can be generated only once, and the reset signal is filtered by the reset signal filtering circuit provided by the embodiment, so that the MCU1 cannot be reset. When the reset signal filtering circuit receives a true power-off signal, the voltage monitoring chip 2 continuously outputs a reset signal of 100ms, but the reset signal filtering unit 3 can only filter one reset signal, so that even if the reset signal is filtered, the reset signal which is continuously output and not filtered is still received by the MCU1, and the MCU1 can reset the reset signal which is not filtered, thereby improving the anti-interference capability of the embedded system.
When the number of the reset signals to be filtered is more than one, the number of the reset signals to be filtered can be estimated according to actual conditions, and then the appropriate resistance is calculated by combining the capacitance charging and discharging formula, and the number of the reset signals to be filtered can be increased by selecting the appropriate capacitance.
In addition, the monitoring voltage of the embedded system can be flexibly adjusted according to the actual situation.
The reset signal filtering circuit provided by the embodiment improves the reset circuit in the prior art. After improvement, the original real-time voltage monitoring function is kept, when microsecond-level interference pulses such as power grid voltage fluctuation, surge, motor start and stop and the like are received and interference signals which cannot cause the halt or the disorderly action of the MCU1 are not generated, wrong reset signals caused by the error reset signals can be filtered and eliminated in time, and a huge stabilizing effect is achieved on an embedded system.
In other embodiments, if the PCB has no volume limitation requirement, the first bi-directional transient suppression diode T1 and the second bi-directional transient suppression diode T2 may be replaced by bi-directional transient suppression diodes with larger power to further increase the immunity of the embedded system to interference.
While the present invention has been described with reference to the particular illustrative embodiments, it will be understood by those skilled in the art that the present invention is not limited thereto, and may be embodied in many different forms without departing from the spirit and scope of the present invention as set forth in the following claims. Any modification which does not depart from the functional and structural principles of the present invention is intended to be included within the scope of the claims.
Claims (9)
1. The utility model provides a reset signal filter circuit for filter reset signal to MCU in embedded system, its characterized in that, reset signal filter circuit includes voltage monitoring chip protection unit, high frequency signal filter unit, voltage monitoring chip and reset signal filter unit, voltage monitoring chip protection unit, high frequency signal filter unit, voltage monitoring chip and reset signal filter unit connect after establishing ties in proper order MCU.
2. The reset signal filtering circuit of claim 1, wherein: the reset signal filtering unit comprises a first bidirectional transient suppression diode, a resistor R1 and an electrolytic capacitor C1, the output end of the voltage monitoring chip is connected with one end of the first bidirectional transient suppression diode, the other end of the first bidirectional transient suppression diode is grounded, the anode of the electrolytic capacitor C1 is connected with the MCU, the cathode of the electrolytic capacitor C1 is grounded, and the resistor R1 is connected with the output end of the voltage monitoring chip and the anode of the electrolytic capacitor C1.
3. The reset signal filtering circuit of claim 2, wherein: the resistance value of the resistor R1 is 20k omega, and the capacitance value of the electrolytic capacitor C1 is 10 muF.
4. The reset signal filtering circuit of claim 1, wherein: the voltage monitoring chip protection unit comprises a second bidirectional transient suppression diode, the working voltage of the embedded system is input from one end of the second bidirectional transient suppression diode, and the other end of the second bidirectional transient suppression diode is grounded.
5. The reset signal filtering circuit of claim 4, wherein: the high frequency signal filtering unit comprises a resistor R2 and a capacitor C2, one end of the capacitor C2 is connected with the input end of the voltage monitoring chip, the other end of the capacitor C2 is grounded, one end of the resistor R2 is connected with one end of the second bidirectional transient suppression diode, which is used for inputting the working voltage of the embedded system, and the other end of the resistor R2 is connected with the input end of the voltage monitoring chip.
6. The reset signal filtering circuit of claim 5, wherein: the resistance value of the resistor R2 is 100 omega, and the capacitance value of the capacitor C2 is 0.1 muF.
7. The reset signal filtering circuit of claim 4, wherein: the second bidirectional transient suppression diode filters interference voltage above 5V.
8. The reset signal filtering circuit of claim 1, wherein: and when the voltage received by the voltage monitoring chip is lower than 2.8V, a low-level signal is output to the reset signal filtering unit.
9. The reset signal filtering circuit of claim 8, wherein: the period of the low level signal is 100 ms.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922058754.3U CN210639607U (en) | 2019-11-25 | 2019-11-25 | Reset signal filter circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922058754.3U CN210639607U (en) | 2019-11-25 | 2019-11-25 | Reset signal filter circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN210639607U true CN210639607U (en) | 2020-05-29 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201922058754.3U Active CN210639607U (en) | 2019-11-25 | 2019-11-25 | Reset signal filter circuit |
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| Country | Link |
|---|---|
| CN (1) | CN210639607U (en) |
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2019
- 2019-11-25 CN CN201922058754.3U patent/CN210639607U/en active Active
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