CN213461545U - Flyback switching power supply with wide output voltage range - Google Patents
Flyback switching power supply with wide output voltage range Download PDFInfo
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- CN213461545U CN213461545U CN202021996190.4U CN202021996190U CN213461545U CN 213461545 U CN213461545 U CN 213461545U CN 202021996190 U CN202021996190 U CN 202021996190U CN 213461545 U CN213461545 U CN 213461545U
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Abstract
The utility model relates to the field of switch power supply, in particular to a flyback switch power supply with wide output voltage range, which comprises a rectifier, a filter circuit, a transformer, a starting circuit, a power chip and a power supply loop of the power chip; the output end of the rectifier is connected with the input end of the filter circuit, and the output end of the filter circuit is connected with the starting circuit and the primary winding of the transformer; the output end of the starting circuit is connected with the power supply chip; the input in power chip power supply loop is connected to the auxiliary winding of transformer, and power chip is connected to power chip power supply loop's output, the utility model discloses increase series voltage stabilizing circuit between auxiliary winding and power chip, guarantee when the wide voltage range of secondary side voltage output, auxiliary winding output is stable, ensures that power chip normal operation, the condition of excessive pressure or under-voltage can not appear to enlarge the output range of power.
Description
Technical Field
The utility model relates to a switching power supply technical field specifically is a flyback switching power supply of wide output voltage scope.
Background
The flyback switching power supply needs to be connected with different types of LED lamps, the types of the LED lamps are different, the serial connection or parallel connection modes are different, the required driving direct current voltage is different, and the LED driving power supply is required to output wide voltage.
At present, a switching power supply adopting a flyback topology structure adopts secondary side feedback, the influence of an output voltage range on the normal working voltage of a primary side control chip is large, if the output voltage range of the secondary side is too large, the primary side control chip can be caused to enter an overvoltage or undervoltage protection state, and finally the primary side control chip can not work.
Disclosure of Invention
The to-be-solved technical problem of the utility model is, improve and turn over the flyback switching power supply output voltage scope, simultaneously, can not lead to former limit control chip work unusual, the utility model provides a flyback switching power supply of wide output voltage scope has increased supplementary power supply voltage stabilizing circuit, ensures that chip operating voltage clock maintains in normal operating range, improves power output voltage.
A flyback switching power supply with a wide output voltage range comprises a rectifying device, a filter circuit, a transformer, a starting circuit, a power chip and a power supply circuit of the power chip;
the transformer comprises a primary winding, a secondary winding and an auxiliary winding;
the output end of the rectifier is connected with the input end of the filter circuit, and the output end of the filter circuit is connected with the starting circuit and the primary winding of the transformer;
the output end of the starting circuit is connected with the power supply chip;
the auxiliary winding of the transformer is connected with the input end of a power supply circuit of the power chip, and the output end of the power supply circuit of the power chip is connected with the power chip;
the power supply circuit of the power supply chip comprises a diode D9, a capacitor C9, a capacitor C20, a resistor R23, a resistor R26, a resistor R19, a resistor R91, a triode Q4 and a voltage regulator tube ZD 1;
the output end of the secondary winding is connected with the anode of a diode D9 and one end of a resistor R23, the other end of a resistor R23 is connected with a resistor R19, the other end of the resistor R19 is connected with a PGND, the cathode of a diode D9 is connected with the first polar plate of a capacitor C9, the collector of a triode Q4 and one end of a resistor R91, the other end of a resistor R91 is connected with the base of the triode Q4 and one end of a voltage regulator ZD1, the other end of the voltage regulator ZD1 is connected with the second polar plate of the capacitor C9 and the PGND, the emitter of the triode Q4 is connected with one end of a resistor R9, and the other end of the resistor R9. The power supply chip adopts a DX8660 chip; the filter circuit is a pi-type filter circuit.
Advantageous effects
The utility model discloses increase series voltage stabilizing circuit between auxiliary winding and power chip, guarantee when the wide voltage range of secondary side voltage output, auxiliary winding output is stable, ensures that power chip normal operation, the excessive pressure or the under-voltage condition can not appear to enlarge the output range of power. Through practical tests, the fact that the range of the output voltage can be expanded by 1 time after the auxiliary power supply voltage stabilizing circuit is added is found.
Drawings
Fig. 1 is a schematic circuit diagram of the present invention.
Detailed Description
A flyback switching power supply with a wide output voltage range comprises a rectifying device, a filter circuit, a transformer, a starting circuit, a power chip and a power supply circuit of the power chip;
the transformer comprises a primary winding, a secondary winding and an auxiliary winding;
the output end of the rectifier is connected with the input end of the filter circuit, and the output end of the filter circuit is connected with the starting circuit and the primary winding of the transformer;
the output end of the starting circuit is connected with the power supply chip;
the auxiliary winding of the transformer is connected with the input end of a power supply circuit of the power chip, and the output end of the power supply circuit of the power chip is connected with the power chip;
the power supply circuit of the power supply chip comprises a diode D9, a capacitor C9, a capacitor C20, a resistor R23, a resistor R26, a resistor R19, a resistor R91, a triode Q4 and a voltage regulator tube ZD 1;
the output end of the secondary winding is connected with the anode of a diode D9 and one end of a resistor R23, the other end of a resistor R23 is connected with a resistor R19, the other end of the resistor R19 is connected with a PGND, the cathode of a diode D9 is connected with the first polar plate of a capacitor C9, the collector of a triode Q4 and one end of a resistor R91, the other end of a resistor R91 is connected with the base of the triode Q4 and one end of a voltage regulator ZD1, the other end of the voltage regulator ZD1 is connected with the second polar plate of the capacitor C9 and the PGND, the emitter of the triode Q4 is connected with one end of a resistor R9, and the other end of the resistor R9. The power supply chip adopts a DX8660 chip; the filter circuit is a pi-type filter circuit.
As shown in fig. 1, the ac power is rectified by the rectifier bridge so that the input voltage and the input current are positive, and then the input voltage and the input current are filtered to the primary winding of the transformer. The starting resistors R21, R28 and R21A charge a power supply capacitor C21 of a DX8660 system of the chip, and when the voltage of the power supply capacitor C21 reaches 19.8V, the chip starts to work. After the chip works, the power supply of the chip system is provided by the auxiliary coil.
When the MOS tube is conducted, input voltage charges a primary winding of the transformer, and according to the polarity of the same-name end of the transformer, Uc is greater than Ud, Ue is greater than Uf, the output of a secondary winding is reversed, and a secondary output diode is reversely biased; the voltage of the auxiliary winding is reversed, and the diode of the auxiliary winding is reversely biased; the system stores energy in a transformer. At the moment, the system discharges electricity to supply power to the load by virtue of the output electrolytic capacitor C7; the auxiliary power supply powers DX8660 by virtue of capacitor C9.
After the MOS tube is switched on, the primary side current is increased sharply, and when the CS voltage of the primary side current detection pin of the chip reaches a threshold value of 1.1V, namely the primary side current reaches a peak value Ipk, the MOS tube is switched off, wherein the switching off is hard switching off.
When the MOS tube is turned off, the primary current is instantaneously reduced to zero, at the moment Uc < Ud and Ue < Uf, the secondary output diode D10 and the auxiliary coil diode D9 are positively biased, and the energy stored in the transformer charges the secondary output electrolytic capacitors C33, C34, C35, C37 and the auxiliary power supply capacitor C9 to make up for the electric energy consumed when the MOS tube is turned on.
The secondary winding and the auxiliary winding have a fixed turn ratio, so that the output voltage range of the secondary winding has a fixed proportional relation with the output voltage range of the auxiliary winding, but because the auxiliary winding directly supplies power to the power chip, the power supply voltage range of the power chip is the voltage range of the auxiliary winding.
If the voltage range of the secondary winding is required to be enlarged, the voltage range of the auxiliary winding must be enlarged, and in order to ensure the normal working range of the power supply chip, a voltage stabilizing circuit is particularly added to the voltage of the auxiliary winding, so that the working requirement of the power supply chip can be still met even if the power supply output voltage range of the auxiliary winding is greatly changed.
The voltage stabilizing circuit comprises a triode Q4, a resistor R91 and a voltage stabilizing tube ZD 1; the voltage is output through the emitter of the transistor Q4, the voltage of the emitter of the transistor Q4 is equal to the base voltage of Q4 minus the voltage difference Vbe between the base and the emitter of Q4, Vbe is actually a diode voltage drop, and the forward voltage drop of a silicon diode or a germanium diode is fixed. When the auxiliary winding outputs a large voltage value and the voltage applied to the two ends of the voltage regulator tube ZD1 reaches the working voltage of the voltage regulator tube ZD1, the base voltage of the triode Q4 is regulated by the voltage regulator tube ZD1, so that the output voltage of the emitter of the triode Q4 is stabilized, and the voltage at the VDD end of the power chip is stabilized.
When the valley bottom detection circuit of the FB pin detects that the voltage (FB value) of the auxiliary coil is reduced to zero, the voltage of the secondary output winding is reduced to zero, namely the energy of the secondary output winding is completely released, the system is in a DCM discontinuous mode, and at the moment, the MOS tube is opened again to store energy for the transformer.
Claims (3)
1. A flyback switching power supply with wide output voltage range is characterized by comprising
The power supply comprises a rectifier, a filter circuit, a transformer, a starting circuit, a power chip and a power chip power supply loop;
the transformer comprises a primary winding, a secondary winding and an auxiliary winding;
the output end of the rectifier is connected with the input end of the filter circuit, and the output end of the filter circuit is connected with the starting circuit and the primary winding of the transformer;
the output end of the starting circuit is connected with the power supply chip;
the auxiliary winding of the transformer is connected with the input end of a power supply circuit of the power chip, and the output end of the power supply circuit of the power chip is connected with the power chip;
the power supply circuit of the power supply chip comprises a diode D9, a capacitor C9, a capacitor C20, a resistor R23, a resistor R26, a resistor R19, a resistor R91, a triode Q4 and a voltage regulator tube ZD 1;
the output end of the secondary winding is connected with the anode of a diode D9 and one end of a resistor R23, the other end of a resistor R23 is connected with a resistor R19, the other end of the resistor R19 is connected with a PGND, the cathode of a diode D9 is connected with the first polar plate of a capacitor C9, the collector of a triode Q4 and one end of a resistor R91, the other end of a resistor R91 is connected with the base of the triode Q4 and one end of a voltage regulator ZD1, the other end of the voltage regulator ZD1 is connected with the second polar plate of the capacitor C9 and the PGND, the emitter of the triode Q4 is connected with one end of a resistor R9, and the other end of the resistor R9.
2. The flyback switching power supply of claim 1, wherein the power chip is a DX8660 chip.
3. The flyback switching power supply of claim 1, wherein the filter circuit is a pi-filter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021996190.4U CN213461545U (en) | 2020-09-14 | 2020-09-14 | Flyback switching power supply with wide output voltage range |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021996190.4U CN213461545U (en) | 2020-09-14 | 2020-09-14 | Flyback switching power supply with wide output voltage range |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN213461545U true CN213461545U (en) | 2021-06-15 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202021996190.4U Active CN213461545U (en) | 2020-09-14 | 2020-09-14 | Flyback switching power supply with wide output voltage range |
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| Country | Link |
|---|---|
| CN (1) | CN213461545U (en) |
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2020
- 2020-09-14 CN CN202021996190.4U patent/CN213461545U/en active Active
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