CN220492978U - Input undervoltage sampling circuit - Google Patents
Input undervoltage sampling circuit Download PDFInfo
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- CN220492978U CN220492978U CN202321289062.XU CN202321289062U CN220492978U CN 220492978 U CN220492978 U CN 220492978U CN 202321289062 U CN202321289062 U CN 202321289062U CN 220492978 U CN220492978 U CN 220492978U
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- 238000005070 sampling Methods 0.000 title claims abstract description 47
- 238000004804 winding Methods 0.000 claims abstract description 44
- 238000002955 isolation Methods 0.000 claims abstract description 24
- 238000004146 energy storage Methods 0.000 claims abstract description 21
- 238000001914 filtration Methods 0.000 claims abstract description 3
- 239000003990 capacitor Substances 0.000 claims description 15
- 230000002265 prevention Effects 0.000 claims description 8
- 238000010168 coupling process Methods 0.000 abstract description 7
- 230000008878 coupling Effects 0.000 abstract description 5
- 238000005859 coupling reaction Methods 0.000 abstract description 5
- 238000011217 control strategy Methods 0.000 description 4
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000010248 power generation Methods 0.000 description 3
- HEZMWWAKWCSUCB-PHDIDXHHSA-N (3R,4R)-3,4-dihydroxycyclohexa-1,5-diene-1-carboxylic acid Chemical compound O[C@@H]1C=CC(C(O)=O)=C[C@H]1O HEZMWWAKWCSUCB-PHDIDXHHSA-N 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000005674 electromagnetic induction Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000008054 signal transmission Effects 0.000 description 1
Classifications
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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
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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- Dc-Dc Converters (AREA)
Abstract
The utility model discloses an input undervoltage sampling circuit which is applied to a switching power supply with a flyback circuit and a control chip, and comprises a winding N2, a sampling voltage dividing circuit, an energy storage filter circuit and a chip control port which are connected in sequence; the winding N2 is used for being coupled with a primary winding N1 of an isolation transformer of the flyback circuit; the sampling voltage division circuit is used for sampling input voltage transmitted through the transformer coupling circuit and dividing the input voltage, the energy storage filter circuit is used for filtering the divided output voltage and outputting the filtered output voltage to the chip control port, and the chip control port is used for being connected with the control end of the control chip of the switching power supply. By the mode, the input undervoltage protection sampling device can realize input undervoltage protection sampling, feed back input voltage signals in real time, effectively reduce the number of devices, reduce the occupied space and realize low cost and miniaturization under the condition of meeting the requirements of high power density and isolation.
Description
Technical Field
The utility model relates to the technical field of electronics, in particular to an input undervoltage sampling circuit applied to a switching power supply circuit with high power density and isolation requirements.
Background
In order to ensure that the DCDC converter can effectively and normally work in a certain fluctuation of input voltage, input voltage signals need to be simultaneously supplied to a control chip so as to adjust an output end control strategy, so that an undervoltage sampling circuit and a corresponding protection circuit are needed to limit the input voltage which is too low, the input current is prevented from being too large, the converter is prevented from working abnormally, and the control strategy of the output end can be adjusted in real time according to the input voltage.
The existing DCDC converter with high power density and high isolation is designed by a multipurpose high-frequency control chip. The control chip is required to monitor the condition of the output end and adjust the control strategy in real time, and is mostly placed on the secondary side, but the high isolation property of the control chip makes the control chip unable to directly sample and detect the input voltage of the primary side. In this case, it is necessary to use an isolation device such as a photocoupler to perform circuit design, and to perform signal transmission between two stages of circuits, thereby achieving an electrical isolation function. The photoelectric coupler is internally integrated with a power generation diode and a photoelectric triode, wherein the power generation diode is connected with a power input end of a primary side, and the photoelectric triode is connected with a current limiting circuit of a secondary side and a control chip port. The power generation diode in the photoelectric coupler is driven by the electric signal to emit light with a certain wavelength, and the light is received by the secondary side photoelectric triode to generate photocurrent, and the photocurrent is further amplified and output to realize that an input voltage signal is transmitted to the control chip at the output end, so that the control strategy is adjusted. The signal in the photoelectric coupler is transmitted unidirectionally, the input end and the output end are completely electrically isolated, and the isolation property of the photoelectric coupler is ensured.
However, the photoelectric coupler required by the scheme has larger volume and high cost, and is inconvenient in miniaturization and low cost due to overlarge occupied area for products with high power density.
Disclosure of Invention
In order to solve the technical problems, the utility model provides an input undervoltage sampling circuit, which is characterized in that a winding is added on an isolation transformer of a flyback circuit to couple primary side input voltage, and the input voltage is sampled to a control chip, so that the sampling of input undervoltage protection is realized, input voltage signals are fed back in real time, isolation requirements are not influenced, devices are fewer, and the cost is low.
The scheme adopted by the utility model is as follows:
in a first aspect, an input undervoltage sampling circuit is provided, and is applied to a switching power supply with a flyback circuit and a control chip, and the switching power supply comprises a winding N2, a sampling voltage dividing circuit, an energy storage filter circuit and a chip control port which are sequentially connected; the winding N2 is used for being coupled with a primary winding N1 of an isolation transformer of the flyback circuit; the sampling voltage division circuit is used for sampling input voltage transmitted through the transformer coupling circuit and dividing the input voltage, the energy storage filter circuit is used for filtering the divided output voltage and outputting the filtered output voltage to the chip control port, and the chip control port is used for being connected with the control end of the control chip of the switching power supply.
Preferably, the anti-negative-pressure circuit is connected in parallel with the energy storage filter circuit and is used for clamping the negative voltage of the chip control port after the switch tube S1 of the flyback circuit is turned off.
Preferably, the sampling voltage division circuit comprises a first resistor R1 and a second resistor R2; one end of the first resistor R1 is connected with the same-name end of the winding N2, and the other end of the first resistor R2, one end of the energy storage filter circuit and the control chip port are connected; the other end of the second resistor R2, the synonym end of the winding N2 and the other end of the energy storage filter circuit are grounded.
Preferably, the tank filter circuit is a capacitor C1.
Preferably, the negative pressure prevention circuit is a diode D1, a cathode of the diode D1 is connected with one end of the energy storage filter circuit and a port of the control chip, and an anode of the diode D1 is grounded with the other end of the energy storage filter circuit.
The second aspect provides an input undervoltage sampling circuit, which is applied to a switching power supply with a flyback circuit and a control chip, and is characterized by comprising a winding N2, a sampling voltage dividing circuit, an energy storage filter circuit, an anti-negative pressure circuit and a chip control port which are sequentially connected;
the chip control port is used for being connected with the control end of the control chip of the switching power supply;
the winding N2 is used for being coupled with a primary winding of an isolation transformer of the flyback circuit;
the sampling voltage division circuit comprises a first resistor R1 and a second resistor R2;
the energy storage filter circuit is a capacitor C1;
the negative pressure prevention circuit is a diode D1;
one end of the first resistor R1 is connected with the same-name end of the winding N2, and the other end of the first resistor R1 is connected with one end of the second resistor R2, one end of the capacitor C1, the cathode of the diode D1 and the port of the control chip; the other end of the second resistor R2, the synonym end of the winding N2, the other end of the capacitor C1 and the anode of the diode D1 are all grounded.
Compared with the prior art, the utility model has the beneficial effects that: according to the utility model, the winding is added on the isolation transformer of the flyback circuit, the primary side input voltage is coupled through the winding and is connected to the control chip through the sampling circuit, so that the sampling voltage proportional to the input voltage is fed back, sampling of the input undervoltage protection is realized under the condition of meeting the isolation attribute, the input voltage signal is fed back in real time, the number of used devices is small, the occupied space is effectively reduced, and the requirements of miniaturization and low cost are met; meanwhile, in order to prevent negative pressure generated in the coupling process of the transformer from damaging the control chip, a negative pressure prevention circuit is added for protection.
Drawings
FIG. 1 is a schematic diagram of an input undervoltage sampling circuit according to the present utility model.
Detailed Description
The present utility model will now be described in further detail with reference to the drawings and examples, it being understood that the specific examples described herein are intended to be illustrative of the utility model rather than limiting. It should be further noted that, for convenience of description, only some, but not all of the circuits related to the present utility model are shown in the drawings.
As shown in fig. 1, in this embodiment, on the basis of the original isolation circuit, because the current density of the main power portion is high, a planar transformer is adopted for design, and there is no design allowance of other windings on the PCB, therefore, a transformer of a flyback module for supplying power to other functional circuits (such as LDO, isolation driving IC, etc.) in the circuit is used as a coupling source of input voltage, a winding is added on the isolation transformer of the flyback circuit to couple primary side input voltage, and is connected to a control chip through a sampling voltage dividing circuit 100 for feedback of sampling voltage proportional to the input voltage, the homonymous end of the primary side winding N1 of the isolation transformer is connected with the power input end Vin, the heteronymous end of the primary side winding N1 is connected with the drain electrode of a switching tube S1, and the source electrode of the switching tube S1 is connected with the power input end GND, wherein, the switching tube S1 is an N-MOS tube. In this embodiment, the scheme adopted is to provide an input under-voltage sampling circuit, which comprises a winding N2, a sampling voltage dividing circuit 100, an energy storage filter circuit 200 and a chip control port which are sequentially connected; the winding N2 is used for being coupled with a primary winding N1 of an isolation transformer of the flyback circuit; the sampling voltage division circuit 100 is configured to sample an input voltage transmitted through the transformer coupling circuit and divide the input voltage, the energy storage filter circuit 200 is configured to filter the divided output voltage and output the filtered output voltage to a chip control port, and the chip control port is configured to be connected to a control end of a control chip of the switching power supply.
According to the voltage of the coupling input end of the transformer, a relatively stable and accurate proportion signal is obtained on the energy storage filter circuit 200 through the sampling voltage dividing circuit 100, the signal is transmitted to the port of the control chip for judgment, and meanwhile, in order to prevent negative pressure generated in the coupling process of the transformer from damaging the control chip, a negative pressure prevention circuit 300 module is added for protection. Through the mode, the input undervoltage protection sampling can be realized, the input voltage signal is fed back in real time, the scheme meets the isolation requirement, the number of used devices is small, the occupied plate space is effectively reduced, and the requirements of miniaturization and low cost are met.
Specifically, the sampling voltage dividing circuit 100 includes a first resistor R1 and a second resistor R2, where the homonymous end of the winding N2 is connected to one end of the first resistor R1, the heteronymous end of the winding N2 is connected to one end of the second resistor R2, and the other end of the first resistor R1 is connected to the other end of the second resistor R2.
The two ends of the second resistor R2 are used as output ports of the sampling voltage-dividing circuit 100, the energy storage filter circuit 200 is a capacitor C1, and the capacitor C1 is connected in parallel with the output ports of the sampling voltage-dividing circuit 100 and is used as an output signal to be transmitted to the control chip ports.
Optionally, since the negative voltage value allowed by the I/O port of the control chip is typically-0.3V, in order to prevent the control chip from being damaged, a negative voltage prevention circuit 300 is connected in parallel between the control chip port and the ground port of the output terminal, specifically, the negative voltage prevention circuit 300 is a diode D1, if the negative voltage is lower than-0.3V, the negative voltage is clamped to-0.3V by the diode, and the control chip still regards the negative voltage as a low level, so that the control chip is not damaged.
Specifically, the specific connection relation between each component in the input under-voltage sampling circuit in this embodiment is as follows: one end of the first resistor R1 is connected with the same-name end of the winding N2, and the other end of the first resistor R1 is connected with one end of the second resistor R2, one end of the capacitor C1, the cathode of the diode D1 and the port of the control chip; the other end of the second resistor R2, the synonym end of the winding N2, the other end of the capacitor C1 and the anode of the diode D1 are all grounded.
The working principle of the embodiment is as follows:
when the power supply supplies power, the voltage of the input end is Vin, and in the normal working process of the flyback circuit, the first working state is as follows: when the switching tube S1 is conducted, the homonymous end of the primary winding N1 is positive according to Lenz' S law, the homonymous end of the winding N2 is positive according to Faraday electromagnetic induction law, and the induced voltage on the winding N2 is Vin/N when the turn ratio of the isolation transformer is assumed to be N. The current flows to the first branch and the second branch, wherein the first branch is the same-name end of the winding N2, the first resistor R1, the second resistor R2 and the output ground port, the second branch is the same-name end of the second winding N2, the first resistor R1, the first capacitor C1, the control chip port and the output ground port, the voltage of the control chip port is the divided voltage of the second resistor R2 at the moment, vin/N (R2/(R1 + R2)), and the voltage can enable the voltage reaching the control chip port to be more stable after being filtered by the capacitor C1.
The second working state: when the switching tube S1 is turned off, the synonym end of the primary winding N1 is positive according to Lenz' S law, so that the synonym end of the winding N2 is also positive, induced current passes through the anode of the diode D1, negative pressure of a port can be clamped at the conduction voltage drop of the diode D1, the reliability of the device is ensured, and meanwhile, the capacitor C1 continuously supplies power for the port of the control chip.
The above is a preferred embodiment of the present utility model, and those skilled in the art to which the present utility model pertains may also make alterations and modifications to the above detailed description, and these improvements and modifications should also be regarded as the scope of the utility model. Therefore, the utility model is not limited to the above-described embodiments, and some modifications and changes of the utility model should fall within the scope of the claims of the utility model. In addition, although specific terms are used in the present specification, these terms are for convenience of description only and do not limit the present utility model in any way.
Claims (6)
1. An input undervoltage sampling circuit is applied to a switching power supply with a flyback circuit and a control chip, and is characterized by comprising a winding N2, a sampling voltage dividing circuit, an energy storage filter circuit and a chip control port which are sequentially connected; the winding N2 is used for being coupled with a primary winding N1 of an isolation transformer of the flyback circuit; the sampling voltage division circuit is used for sampling the input voltage transmitted through the isolation transformer and dividing the input voltage, the energy storage filter circuit is used for filtering the divided output voltage and outputting the filtered output voltage to the chip control port, and the chip control port is used for being connected with the control end of the control chip of the switching power supply.
2. The under-input voltage sampling circuit according to claim 1, further comprising an anti-negative voltage circuit connected in parallel with the tank filter circuit for clamping a negative voltage of the chip control port after the switching tube S1 of the flyback circuit is turned off.
3. The under-input voltage sampling circuit according to any one of claims 1 or 2, wherein the sampling voltage dividing circuit comprises a first resistor R1 and a second resistor R2; one end of the first resistor R1 is connected with the same-name end of the winding N2, and the other end of the first resistor R2, one end of the energy storage filter circuit and the chip control port are connected; the other end of the second resistor R2, the synonym end of the winding N2 and the other end of the energy storage filter circuit are grounded.
4. The under-input voltage sampling circuit of claim 3, wherein the tank filter circuit is a capacitor C1.
5. The input undervoltage sampling circuit according to claim 2, wherein the negative pressure prevention circuit is a diode D1, a cathode of the diode D1 is connected with one end of the tank filter circuit and a control chip port, and an anode of the diode D1 is grounded with the other end of the tank filter circuit.
6. An input undervoltage sampling circuit is applied to a switching power supply with a flyback circuit and a control chip, and is characterized by comprising a winding N2, a sampling voltage dividing circuit, an energy storage filter circuit, an anti-negative-pressure circuit and a chip control port which are connected in sequence;
the chip control port is used for being connected with the control end of the control chip of the switching power supply;
the winding N2 is used for being coupled with a primary winding of an isolation transformer of the flyback circuit;
the sampling voltage division circuit comprises a first resistor R1 and a second resistor R2;
the energy storage filter circuit is a capacitor C1;
the negative pressure prevention circuit is a diode D1;
one end of the first resistor R1 is connected with the same-name end of the winding N2, and the other end of the first resistor R1 is connected with one end of the second resistor R2, one end of the capacitor C1, the cathode of the diode D1 and the chip control port; the other end of the second resistor R2, the synonym end of the winding N2, the other end of the capacitor C1 and the anode of the diode D1 are all grounded.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321289062.XU CN220492978U (en) | 2023-05-25 | 2023-05-25 | Input undervoltage sampling circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321289062.XU CN220492978U (en) | 2023-05-25 | 2023-05-25 | Input undervoltage sampling circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN220492978U true CN220492978U (en) | 2024-02-13 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202321289062.XU Active CN220492978U (en) | 2023-05-25 | 2023-05-25 | Input undervoltage sampling circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN220492978U (en) |
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2023
- 2023-05-25 CN CN202321289062.XU patent/CN220492978U/en active Active
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