CN219477591U - Under-voltage protection circuit of DC/DC converter - Google Patents
Under-voltage protection circuit of DC/DC converter Download PDFInfo
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- CN219477591U CN219477591U CN202320367061.6U CN202320367061U CN219477591U CN 219477591 U CN219477591 U CN 219477591U CN 202320367061 U CN202320367061 U CN 202320367061U CN 219477591 U CN219477591 U CN 219477591U
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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
In order to solve the problem that the whole circuit does not have a protection function because the CS end voltage value of a pulse width modulator is not shut down and locked when the DC/DC converter is in no-load state and has no hysteresis function between the under-voltage shutdown and the startup when the DC/DC converter is in normal operation and loaded state, the utility model designs a voltage dividing circuit comprising a resistor R1 and a resistor R2, wherein R3 is a feedback resistor, gain control is determined by the three resistors, a filter circuit comprising a capacitor C1 is designed, an output end is connected to a COMP port of the pulse width modulator IC1, and when the voltage value of the output end of the comparator is in low level, the COMP port of the pulse width modulator IC1 is shut down to output voltage so as to achieve the protection.
Description
Technical Field
The utility model relates to the technical field of DC/DC converters, in particular to an under-voltage protection circuit of a DC/DC converter.
Background
The undervoltage protection function is an important index of the DC/DC converter which can be used in the whole machine system at present, when the input voltage in the whole machine system is too low, namely the input voltage is not in a specified range, the DC/DC converter cannot work normally, if the DC/DC converter is in an undervoltage input state for a long time, the internal devices of the DC/DC converter are damaged due to the fact that the born voltage and current stress exceed the normal use range, and the failure of the DC/DC converter is caused, so the undervoltage protection function is generally required to stop the occurrence of the phenomenon, and the reliability and the safety of the DC/DC converter are improved.
When the line voltage is reduced to the critical voltage, the protection circuit mainly has the task of reducing the failure probability of the pulse width modulator and improving the stability of the whole system.
The undervoltage protection circuit of the traditional DC/DC converter is common: the change of the CS terminal voltage value of the pulse width modulator IC1 plays a role of a protection circuit, the traditional circuit is simple and saves space, and the defect is that when the DC/DC converter works in an idle state, the CS terminal voltage value of the pulse width modulator is not shut down and locked after a plurality of periods, so that the whole circuit does not play a role of protection, the DC/DC converter still works normally, and no hysteresis function exists between under-voltage turn-off and turn-on during load.
Disclosure of Invention
In order to solve the problem that when the DC/DC converter works in an idle state, the CS end voltage value of the pulse width modulator is not shut down and locked after a plurality of periods, so that the whole circuit does not have a protection function, the DC/DC converter still works normally, and when the DC/DC converter is loaded, no hysteresis function exists between under-voltage turn-off and turn-on.
The technical scheme of the utility model is as follows: the undervoltage protection circuit of the DC/DC converter comprises a voltage comparator Q1, a pulse width modulator IC1, a voltage dividing circuit consisting of a resistor R1 and a resistor R2, a feedback resistor R3 and a filter circuit consisting of a capacitor C1;
the non-inverting input end of the voltage comparator Q1 is connected with the sampling voltages of the sampling resistor R1 and the sampling resistor R2, the inverting input end of the voltage comparator Q1 is connected with the REF end of the pulse width modulator IC1, and the output end of the voltage comparator Q1 is connected with the COMP end of the pulse width modulator IC 1;
COMP of pulse width modulator IC1 is connected with the non-inverting input end of Q1 through feedback resistor R3
The pulse width modulator IC1 is connected with the VCC end of the voltage comparator Q1, and a filter circuit formed by a capacitor C1 is connected between the pulse width modulator IC1 and the VCC end.
The voltage dividing circuit is as follows: r1 is connected to the input voltage and R2 is connected to GND.
The filter circuit formed by the capacitor C1 is that the capacitor C1 is connected with GND.
The utility model has the following beneficial effects:
the utility model has ingenious circuit design, and realizes the under-voltage protection function of the DC/DC converter by combining devices such as a voltage comparator, a pulse width modulator, a resistor and the like.
The utility model saves space, is not affected by other circuits in the interior, and can be used for multiplexing DC/DC converters.
The utility model has good output control capability, can solve the undervoltage protection function of the DC/DC converter which is used in the whole system by turning off the COMP end of the pulse width modulator IC1 of the DC/DC converter, and can also ensure that the whole DC/DC converter has hysteresis function in the undervoltage state. Meanwhile, the scheme has good universality, the voltage value range of the DC/DC converter, which needs to be turned on and off under the condition of different conditions, can be realized through simple resistance parameter change, and the design scheme of the function is simple and has good universality, good popularization space and wider application field.
Drawings
Fig. 1 is a schematic diagram of a prior art circuit principle.
Fig. 2 is a schematic circuit diagram of the present utility model.
Detailed Description
The present utility model will be described in detail with reference to the accompanying drawings.
In order to make the objects, technical solutions and advantages of the present utility model more apparent, the technical solutions of the present utility model will be described in detail below. It will be apparent that the described embodiments are only some, but not all, embodiments of the utility model. All other embodiments, which can be made by a person of ordinary skill in the art based on the examples of the utility model without any inventive effort, are within the scope of the utility model.
The undervoltage protection circuit of the DC/DC converter comprises a voltage comparator Q1, a pulse width modulator IC1, a voltage dividing circuit consisting of a resistor R1 and a resistor R2, a feedback resistor R3 and a filter circuit consisting of a capacitor C1;
the non-inverting input end of the voltage comparator Q1 is connected with the sampling voltages of the sampling resistor R1 and the sampling resistor R2, the inverting input end of the voltage comparator Q1 is connected with the REF end of the pulse width modulator IC1, and the output end of the voltage comparator Q1 is connected with the COMP end of the pulse width modulator IC 1;
COMP of pulse width modulator IC1 is connected with the non-inverting input end of Q1 through feedback resistor R3
The pulse width modulator IC1 is connected with the VCC end of the voltage comparator Q1, and a filter circuit formed by a capacitor C1 is connected between the pulse width modulator IC1 and the VCC end.
The voltage dividing circuit is as follows: r1 is connected to the input voltage and R2 is connected to GND.
The filter circuit composed of the capacitor C1 is that the capacitor C1 is connected with GND.
As shown in fig. 1, the circuit in the prior art is simple and saves space, and has the defects that when the DC/DC converter works in an idle state, the CS terminal voltage value of the pulse width modulator is not turned off and locked after a plurality of periods, so that the whole circuit does not have a protection function, the DC/DC converter still works normally, and no hysteresis function exists between the under-voltage turn-off and turn-on when the DC/DC converter is loaded.
As shown in fig. 2, the utility model provides an undervoltage protection circuit of a DC/DC converter, which is characterized by comprising a voltage dividing circuit consisting of a resistor R1 and a resistor R2, wherein the voltage dividing circuit consists of a voltage comparator Q1 and a pulse width modulator IC1, and the voltage dividing circuit consists of a feedback resistor and a filter circuit consisting of a capacitor C1;
the non-inverting input end of the voltage comparator Q1 is connected with the sampling voltages of the two sampling resistors R1 and R2, the inverting input end of the voltage comparator Q1 is connected with the REF end of the pulse width modulator IC1, and the output end of the voltage comparator Q1 is connected with the COMP end of the pulse width modulator IC 1;
the VCC end of the pulse width modulator IC1 is connected with the VCC end of the voltage comparator Q1, and the power supply circuits of the two devices consist of linear power supply resistors; .
The circuit voltage comparator Q1 uses the detected output voltage variation to control the COMP terminal of the pulse width modulator IC1 to realize the function of the protection circuit.
The specific process is as follows: the resistors R1 and R2 form a pair of voltage division sampling resistors, R3 is feedback voltage, and the voltage of the non-inverting input end of the voltage comparator Q1 is calculated
Wherein Vin is the input voltage of the turn-off point set by the DC/DC converter, vout is the COMP terminal voltage of the pulse width modulator IC1 in the normal operation state of the DC/DC converter, V is the inverted input voltage, that is, the reference voltage of the pulse width modulator IC1, as the reference voltage, the relation formula of the resistors R1 and R2 is calculated from the above formula, and it is assumed that one R1 resistance value and the other resistance value can be calculated. When the input voltage enters, comparing the input voltage with an inverted input voltage reference, and if the homodromous input voltage is higher than the reference, outputting a high level, wherein the pulse width modulator IC1 works normally; when the in-phase input voltage is lower than the reference voltage, a low level is output, the COMP terminal voltage of the pulse width modulator IC1 is turned off, and the pulse width modulator IC1 does not work, so that the purpose of under-voltage protection is achieved. The DC/DC converter has the function of under-voltage protection no matter in no-load state or in load state, and has the hysteresis function between under-voltage turn-off and turn-on. The voltage value range of the DC/DC converter, which needs to be turned on and off under the undervoltage under different conditions, can be realized through simple resistance parameter change, and different performance index requirements are met.
The undervoltage protection circuit of the DC/DC converter has the advantages that the voltage comparator turns off the COMP end voltage value of the pulse width modulator IC1 to play a role of a protection circuit, so that the DC/DC converter has an undervoltage protection function and a hysteresis function when meeting the no-load state operation, the hysteresis circuit is arranged inside the voltage comparator, the speed is high, and the circuit has the advantages of simple components, good universality, flexible application and the like.
The foregoing is merely a specific embodiment of the present utility model, but the scope of the present utility model is not limited thereto, and any changes or substitutions easily conceivable by those skilled in the art within the technical scope of the present utility model should be included in the scope of the present utility model.
Claims (3)
1. The undervoltage protection circuit of the DC/DC converter comprises a voltage comparator Q1 and a pulse width modulator IC1, and is characterized in that: the circuit also comprises a voltage dividing circuit consisting of a resistor R1 and a resistor R2, a feedback resistor R3 and a filter circuit consisting of a capacitor C1;
the non-inverting input end of the voltage comparator Q1 is connected with the sampling voltages of the sampling resistor R1 and the sampling resistor R2, the inverting input end of the voltage comparator Q1 is connected with the REF end of the pulse width modulator IC1, and the output end of the voltage comparator Q1 is connected with the COMP end of the pulse width modulator IC 1;
the COMP of the pulse width modulator IC1 is connected with the non-inverting input end of the Q1 through a feedback resistor R3, the pulse width modulator IC1 is connected with the VCC end of the voltage comparator Q1, and a filter circuit formed by a capacitor C1 is connected between the pulse width modulator IC1 and the VCC end.
2. The undervoltage protection circuit of a DC/DC converter of claim 1, wherein: the voltage dividing circuit is as follows: r1 is connected to the input voltage and R2 is connected to GND.
3. The undervoltage protection circuit of a DC/DC converter of claim 1, wherein: the filter circuit formed by the capacitor C1 is that the capacitor C1 is connected with GND.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320367061.6U CN219477591U (en) | 2023-03-02 | 2023-03-02 | Under-voltage protection circuit of DC/DC converter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320367061.6U CN219477591U (en) | 2023-03-02 | 2023-03-02 | Under-voltage protection circuit of DC/DC converter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN219477591U true CN219477591U (en) | 2023-08-04 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202320367061.6U Active CN219477591U (en) | 2023-03-02 | 2023-03-02 | Under-voltage protection circuit of DC/DC converter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN219477591U (en) |
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2023
- 2023-03-02 CN CN202320367061.6U patent/CN219477591U/en active Active
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