CN217486156U - Sampling circuit of input over-voltage and under-voltage protection circuit - Google Patents
Sampling circuit of input over-voltage and under-voltage protection circuit Download PDFInfo
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- CN217486156U CN217486156U CN202221091730.3U CN202221091730U CN217486156U CN 217486156 U CN217486156 U CN 217486156U CN 202221091730 U CN202221091730 U CN 202221091730U CN 217486156 U CN217486156 U CN 217486156U
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- voltage
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- signal output
- undervoltage protection
- division circuit
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
Abstract
The utility model discloses a sampling circuit of undervoltage protection circuit is crossed in input, including first divider circuit, second divider circuit, shunt resistor and switch tube, the first termination of first divider circuit connects the positive pole of DC power supply input, and the second end ground connection, the voltage signal output part of first divider circuit connects the voltage sampling signal input part of undervoltage protection chip, and the first end of switch tube connects the voltage signal output part of first divider circuit through shunt resistor, and the second end ground connection of switch tube; the first end of the second voltage division circuit is connected with the voltage signal output end of the first voltage division circuit, and the second end of the second voltage division circuit is grounded; the control end of the switch tube is connected with the voltage signal output end of the second voltage division circuit. The utility model discloses can extend the scope of crossing undervoltage protection chip and crossing undervoltage protection, it is big to satisfy electric wire netting voltage fluctuation, has the switching power supply's of wide range voltage input demand.
Description
[ technical field ]
The utility model relates to a switching power supply especially relates to an input sampling circuit who crosses undervoltage protection circuit.
[ background art ]
In the existing switching power supply, it is generally required to have an input over-voltage and under-voltage protection function. The input over-voltage and under-voltage protection function is used for preventing the power supply or power supply equipment from being damaged due to the fact that input voltage is too low or too high, and the power supply is controlled to be turned off through the protection circuit when the input voltage is too low or too high. Traditional crossing undervoltage protection circuit includes sampling circuit and crosses undervoltage protection chip, as shown in fig. 1, sampling circuit includes bleeder circuit, bleeder circuit's first termination direct current power supply input end anodal DC +, second end ground connection, bleeder circuit's voltage signal output end connects the voltage sampling signal input VIN of crossing undervoltage protection chip. The threshold value of the overvoltage and undervoltage protection chip is usually matched through resistance sampling, and when the voltage signal output by the sampling circuit is lower than the undervoltage protection set value of the overvoltage and undervoltage protection chip or higher than the overvoltage protection set value of the overvoltage and undervoltage protection chip, the main circuit of the switching power supply is switched off by the overvoltage and undervoltage protection chip.
However, in a service environment with large power grid fluctuation, such as an electricity meter service environment, the voltage range required for input is 65V-500Vac, and the overvoltage protection set value and the undervoltage protection set value of the overvoltage and undervoltage protection chip cannot be simultaneously satisfied by using the voltage dividing circuit as the sampling circuit for inputting the overvoltage and undervoltage protection circuit.
[ summary of the invention ]
The to-be-solved technical problem of the utility model is to provide a sampling circuit that can adapt to the electric wire netting voltage fluctuation big, has the input of wide range voltage input demand to cross undervoltage protection circuit.
In order to solve the technical problem, the utility model adopts the technical scheme that a sampling circuit of an input undervoltage protection circuit comprises a first voltage division circuit, a second voltage division circuit, a shunt resistor and a switch tube, wherein the first end of the first voltage division circuit is connected with the anode of a direct current power supply input end, the second end of the first voltage division circuit is grounded, the voltage signal output end of the first voltage division circuit is connected with the voltage sampling signal input end of an undervoltage protection chip, the first end of the switch tube is connected with the voltage signal output end of the first voltage division circuit through the shunt resistor, and the second end of the switch tube is grounded; the first end of the second voltage division circuit is connected with the voltage signal output end of the first voltage division circuit, and the second end of the second voltage division circuit is grounded; and the control end of the switch tube is connected with the voltage signal output end of the second voltage division circuit.
In the sampling circuit, the switch tube is an MOS tube, a drain of the MOS tube is connected to the voltage signal output terminal of the first voltage-dividing circuit through a shunt resistor, a source of the MOS tube is grounded, and a gate of the MOS tube is connected to the voltage signal output terminal of the second voltage-dividing circuit.
The sampling circuit comprises a first filter capacitor and a second filter capacitor, wherein the first filter capacitor is connected between the voltage signal output end of the second voltage division circuit and the ground, and the second filter capacitor is connected between the voltage signal output end of the first voltage division circuit and the ground.
The utility model discloses an input is crossed undervoltage protection circuit and can be extended the scope of crossing undervoltage protection chip and cross undervoltage protection, and it is big to satisfy electric wire netting voltage fluctuation, has wide range voltage input's switching power supply's demand.
[ description of the drawings ]
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
Fig. 1 is a sampling circuit of a prior art input over-voltage and under-voltage protection circuit.
Fig. 2 is the embodiment of the utility model provides a sampling circuit who inputs under-voltage protection circuit.
[ detailed description of the invention ]
The embodiment of the utility model provides an input undervoltage protection circuit's sampling circuit's structure is shown in FIG. 2, including first divider circuit, second divider circuit, shunt resistance R5, MOS pipe Q1, first filter capacitance C1 and second filter capacitance C2.
The first voltage division circuit is formed by sequentially connecting a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a resistor R8 in series. One end of the first voltage division circuit close to the resistor R1 is connected with the anode DC + of the direct-current power supply input end, one end close to the resistor R8 is grounded, and the connection point of the first voltage division circuit, namely the resistor R8 and the resistor R4, is used as the voltage signal output end of the first voltage division circuit and is connected with the voltage sampling signal input end VIN of the overvoltage protection chip.
The second voltage divider is formed by connecting a resistor R6 and a resistor R7 in series. The first end of the second voltage division circuit is connected with the voltage signal output end of the first voltage division circuit, one end of the second voltage division circuit close to the resistor R6 is connected with the voltage signal output end of the first voltage division circuit, and one end close to the resistor R7 is grounded.
The drain of the MOS transistor Q1 is connected to the voltage signal output terminal of the first voltage-dividing circuit through a shunt resistor R5, the source of the MOS transistor Q1 is grounded, and the gate of the MOS transistor Q1 is connected to the voltage signal output terminal of the second voltage-dividing circuit (the connection point of the resistor R6 and the resistor R7).
The first filter capacitor C1 is connected between the voltage signal output terminal of the second voltage-dividing circuit and ground, and the second filter capacitor C2 is connected between the voltage signal output terminal of the first voltage-dividing circuit and ground.
The Voltage sampling signal VIN of the undervoltage protection chip generally sets three voltages, PWM Turn-Off Threshold Voltage, PWM Turn-On Threshold Voltage, and PWM Protect Threshold Voltage. When the Voltage value sampled by VIN is lower than PWM Turn-Off Threshold Voltage, the overvoltage and undervoltage protection chip triggers undervoltage protection, and the overvoltage and undervoltage protection chip closes PWM output. When the sampled Voltage value is larger than the PWM Turn-On Threshold Voltage, the overvoltage and undervoltage protection chip turns On the PWM output power supply to normally work. When the sampled Voltage value is higher than PWM Protect Threshold Voltage, triggering overvoltage protection, turning off PWM by the overvoltage and undervoltage protection chip, and turning off output by the main circuit of the power supply.
The utility model discloses above embodiment suitably improves resistance R8, resistance R6 and resistance R7 for resistance R1, resistance R2, resistance R3 and resistance R4's resistance, can reduce the direct current power supply input and trigger undervoltage protection's magnitude of voltage.
When the gate voltage of the MOS transistor Q1 reaches the threshold value of the conduction of the MOS transistor Q1, the shunt resistor R5 is connected in parallel with the series-parallel circuit formed by the resistor R8, the resistor R6 and the resistor R7, so that the output voltage of the first voltage division circuit is reduced, and the voltage value of the direct-current power supply input terminal for triggering overvoltage protection is correspondingly increased.
The utility model discloses undervoltage protection circuit is crossed in input of above embodiment can extend the scope of crossing undervoltage protection chip and crossing undervoltage protection. To meet the requirements of switching power supplies for a wide range of input voltages.
Claims (3)
1. A sampling circuit for inputting an overvoltage and undervoltage protection circuit comprises a first voltage division circuit, wherein the first end of the first voltage division circuit is connected with the anode of a direct-current power supply input end, the second end of the first voltage division circuit is grounded, and the voltage signal output end of the first voltage division circuit is connected with the voltage sampling signal input end of an overvoltage and undervoltage protection chip; the first end of the second voltage division circuit is connected with the voltage signal output end of the first voltage division circuit, and the second end of the second voltage division circuit is grounded; the control end of the switch tube is connected with the voltage signal output end of the second voltage division circuit.
2. The sampling circuit according to claim 1, wherein the switching transistor is a MOS transistor, a drain of the MOS transistor is connected to the voltage signal output terminal of the first voltage-dividing circuit through a shunt resistor, a source of the MOS transistor is grounded, and a gate of the MOS transistor is connected to the voltage signal output terminal of the second voltage-dividing circuit.
3. The sampling circuit of claim 1, comprising a first filter capacitor coupled between the voltage signal output of the second voltage divider circuit and ground, and a second filter capacitor coupled between the voltage signal output of the first voltage divider circuit and ground.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202221091730.3U CN217486156U (en) | 2022-05-09 | 2022-05-09 | Sampling circuit of input over-voltage and under-voltage protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202221091730.3U CN217486156U (en) | 2022-05-09 | 2022-05-09 | Sampling circuit of input over-voltage and under-voltage protection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN217486156U true CN217486156U (en) | 2022-09-23 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202221091730.3U Active CN217486156U (en) | 2022-05-09 | 2022-05-09 | Sampling circuit of input over-voltage and under-voltage protection circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN217486156U (en) |
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2022
- 2022-05-09 CN CN202221091730.3U patent/CN217486156U/en active Active
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