CN212343641U - Switch power supply starting circuit - Google Patents
Switch power supply starting circuit Download PDFInfo
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- CN212343641U CN212343641U CN202021434855.2U CN202021434855U CN212343641U CN 212343641 U CN212343641 U CN 212343641U CN 202021434855 U CN202021434855 U CN 202021434855U CN 212343641 U CN212343641 U CN 212343641U
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Abstract
The utility model provides a switching power supply starting circuit, include: the transformer comprises an input rectification filter circuit, a starting circuit, a transformer, an output rectification filter circuit, a feedback circuit, a first photoelectric coupler and a power management chip, wherein the power management chip is respectively connected with the output end of the first photoelectric coupler, the output end of the feedback circuit and a primary coil of the transformer; after the first photoelectric coupler is electrified, the starting circuit is conducted, and the power management chip and the transformer are started and work; after the first photoelectric coupler is powered off, the power management chip stops working and enters a standby state, and at the moment, the standby power consumption of the power management chip is equal to zero. Compared with the prior art, the utility model discloses a zero-power consumption under the realization standby mode that switching power supply starting circuit can be real.
Description
Technical Field
The utility model relates to a switching power supply starting circuit belongs to power technical field.
Background
In the prior art, certain power loss exists when a switching power supply is in a no-load mode after being started, and no power supply with no-load power consumption of only a few milliwatts and output power of a few watts exists in the market at present. Both precise theoretical calculation and a large number of actual detections prove that the switch power supply no-load power consumption can not be reduced to several milliwatts for the following three main reasons: firstly, a power management chip with larger self power consumption is used, secondly, a semiconductor element works in a state with quiescent current, and thirdly, the power consumption of a starting resistor is too large.
In addition, in the prior art, under the condition that no other auxiliary power supply circuit exists, there is no way to directly turn off the VCC power supply of the main control chip after the product is used up.
In view of the above, there is a need for an improved starting circuit of a switching power supply to solve the above problems.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a switching power supply starting circuit, this switching power supply starting circuit can really realize the zero-power consumption under the standby mode.
In order to achieve the above object, the utility model provides a switching power supply starting circuit, include:
the input end of the input rectifying filter circuit is connected with an alternating current power supply;
the input end of the starting circuit is connected with the output end of the input rectifying and filtering circuit;
the transformer comprises a primary coil, a secondary coil and a feedback coil, wherein the primary coil is arranged on one side of the transformer and connected with the output end of the input rectifying and filtering circuit, and the secondary coil is arranged on the other side of the transformer;
the input end of the output rectifying filter circuit is connected with the secondary coil of the transformer;
the input end of the feedback circuit is connected with the feedback coil, and the input end of the feedback circuit is also connected with the output end of the output rectifying and filtering circuit;
the first photoelectric coupler is respectively connected with the output end of the starting circuit and an external battery; and
the power management chip is respectively connected with the output end of the first photoelectric coupler, the output end of the feedback circuit and the primary coil of the transformer;
after the first photoelectric coupler is electrified, the starting circuit is conducted, and the power management chip and the transformer are started and work; after the first photoelectric coupler is powered off, the power management chip stops working and enters a standby state, and at the moment, the standby power consumption of the power management chip is equal to zero.
As a further improvement, first photoelectric coupler includes first light emitting source and first photic ware, first light emitting source links to each other with the positive pole of external battery, the one end of first photic ware with starting circuit's output links to each other, the other end with the power management chip links to each other, with after the first light emitting source circular telegram, first photic ware output voltage makes starting circuit with the power management chip switches on.
As a further improvement of the present invention, the starting circuit includes at least one starting resistor connected between the output of the input rectifying and filtering circuit and the first light receiver.
As a further improvement of the present invention, the output rectifying and filtering circuit includes a diode and an output filter capacitor connected to the secondary coil of the transformer, and the diode is connected to the secondary coil in series, and the output filter capacitor is connected to the secondary coil in parallel.
As a further improvement, the feedback circuit includes a reverse cut-off rectifier tube having one end connected to the feedback coil, the other end connected to the power management chip, and one end connected to the feedback coil, the other end connected to the first photoelectric coupler, and the dc negative feedback resistor is connected to the CS pin of the power management chip.
As a further improvement of the present invention, the switching power supply starting circuit further includes a switch device connected between the power management chip and the transformer, the switch device is used for controlling the transformer to start or turn off according to the control signal output by the power management chip.
As a further improvement of the utility model, switching device is field effect transistor, just field effect transistor's grid with the Gate pin of power management chip links to each other, the drain electrode with the primary coil of transformer links to each other, source electrode ground connection, still be connected with parasitic diode between field effect transistor's the source electrode and the drain electrode, parasitic diode is along the one-way conduction of direction of source electrode to drain electrode.
As a further improvement, the switching power supply starting circuit further includes a battery detection circuit, the battery detection circuit includes a voltage regulator tube connected with the output rectification filter circuit, a fourth resistor connected with the voltage regulator tube in series and a second photoelectric coupler connected with the fourth resistor in series, the second photoelectric coupler includes a second light emitting source and a second light receiver, just the second light emitting source with the fourth resistor is connected the second light receiver with the power management chip is connected.
As a further improvement, the second light receiver of the second photoelectric coupler has one end connected to the FB pin of the power management chip and the other end grounded.
As a further improvement, the power management chip is further provided with an RT pin, and the RT pin is grounded through a timing resistor.
The utility model has the advantages that: the utility model discloses a switching power supply starting circuit utilizes first photoelectric coupler to drive the start and stop of power management chip, and after first photoelectric coupler got electric, starting circuit switched on, power management chip and transformer started and work; when the first photoelectric coupler is powered off, the power management chip stops working and enters a standby state, and the standby power consumption of the power management chip is equal to zero at the moment. Compared with the prior art, the utility model discloses a zero-power consumption under the realization standby mode that switching power supply starting circuit can be real.
Drawings
Fig. 1 is a block diagram of the switching power supply start circuit of the present invention.
Fig. 2 is a circuit diagram of the switching power supply start circuit of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in detail with reference to the accompanying drawings and specific embodiments.
As shown in fig. 1 and 2, the utility model discloses a switching power supply starting circuit, including input rectification filter circuit, starting circuit, transformer T1, output rectification filter circuit, feedback circuit, first optoelectronic coupler (U2A, U2B), power management chip and battery detection circuit, the mainly used charges to miniwatt products such as cell-phones.
The input end of the input rectifying and filtering circuit is connected with an alternating current mains supply IN and is used for rectifying and filtering the power frequency mains supply into pulse direct current; IN this embodiment, the input rectifying and filtering circuit mainly includes a filtering capacitor C1, one end of the filtering capacitor C1 is connected to the ac mains IN, and the other end is connected to the GND pin (ground) of the power management chip U1. Of course, in other embodiments, a bridge circuit may be added as needed, and is not limited herein.
The input end of the starting circuit is connected with the output end of the input rectifying and filtering circuit and is mainly used for providing starting current for the power management chip U1. In general, the starting circuit is formed by connecting a plurality of large-resistance resistors in series, and in this embodiment, the starting circuit includes a first starting resistor R1 and a second starting resistor R2 connected to the output end of the input rectifying and filtering circuit.
The transformer T1 includes a primary coil disposed on one side of the transformer T1, a secondary coil disposed on the other side of the transformer T1, and a feedback coil; the primary coil is connected with the output end of the input rectifying and filtering circuit, is used for carrying out safe electrical isolation on the power output end and commercial power, and can also play a role in electric energy transmission, voltage distribution and feedback voltage generation.
The input end of the output rectifying and filtering circuit is connected with the secondary coil and is used for rectifying and filtering the high-frequency current output by the secondary coil of the transformer T1 and outputting stable direct current to a load (such as a mobile phone). In this embodiment, the output rectifying and smoothing circuit includes a diode D1 and an output smoothing capacitor C2 connected to the secondary winding of the transformer T1, the diode D1 is connected in series with the secondary winding, and the output smoothing capacitor C2 is connected in parallel with the secondary winding and grounded.
The input end of the feedback circuit is connected with the feedback coil, the input end of the feedback circuit is also connected with the output end of the output rectifying and filtering circuit, and the feedback circuit is mainly used for transmitting a received feedback signal to the power management chip U1 and controlling the starting or the disconnection of the whole switching power supply starting circuit through the power management chip U1. In this embodiment, the feedback circuit includes a dc negative feedback resistor RS having one end connected to the feedback coil and the other end connected to the power management chip U1, and a reverse blocking rectifier tube D2 having one end connected to the feedback coil and the other end connected to the first photocoupler, where the dc negative feedback resistor RS is connected to the CS pin of the power management chip U1, and is configured to feed back the detected current signal to the power management chip U1.
The first photoelectric coupler is respectively connected with the output end of the starting circuit and an external battery; the power management chip U1 is respectively connected with the output end of the first photoelectric coupler, the output end of the feedback circuit and the primary coil of the transformer T1, so that after the first photoelectric coupler is electrified, the starting circuit is conducted, and the power management chip U1 and the transformer T1 are started and start to work normally; after the first photoelectric coupler is powered off, the power management chip U1 stops working and enters a standby state, and at the moment, the standby power consumption of the power management chip U1 is equal to zero.
Specifically, the first photocoupler includes a first light emitting source U2A and a first light receiver U2B, the first light emitting source U2A is connected to the positive electrode BAT + of the external battery, one end of the first light receiver U2B is connected to the output end of the start circuit, and the other end is connected to the VDD pin of the power management chip U1, so that after the first light emitting source U2A is powered on, the first light receiver U2B outputs a voltage to turn on the start circuit and the power management chip U1. Preferably, the first start resistor R1 and the second start resistor R2 are connected between the output end of the input rectifying and filtering circuit and the first light receiver U2B, the reverse cut-off rectifying tube D2 is connected to the first light receiver U2B, a resistor R3 is further connected between the first light-emitting source U2A and the positive electrode BAT + of the external battery, and the other end of the first light-emitting source U2A is grounded.
The power management chip U1 still is equipped with the RT pin, the RT pin is through a timing resistance RT ground connection.
The switching power supply starting circuit further comprises a switching device Q1 connected between a power management chip U1 and a transformer T1, wherein the switching device Q1 is used for controlling the transformer T1 to be started or shut down according to a control signal output by the power management chip U1. Specifically, the switching device Q1 is a field effect transistor (MOS transistor), a Gate (G pole) of the field effect transistor Q1 is connected to a Gate pin of the power management chip U1, a drain (D pole) is connected to the primary coil of the transformer T1, a source (S pole) is grounded, a parasitic diode D3 is further connected between the source (S pole) and the drain (D pole) of the field effect transistor Q1, and the parasitic diode D3 is unidirectionally turned on along a direction from the source (S pole) to the drain (D pole).
The switching power supply starting circuit also comprises a battery detection circuit which is mainly used for detecting the output voltage of the battery and transmitting the detected voltage value and the isolation signal to the power management chip U1. The battery detection circuit comprises a voltage regulator tube Z connected with the output rectifying and filtering circuit, a fourth resistor R4 connected with the voltage regulator tube Z in series, and a second photoelectric coupler (U3A, U3B) connected with the fourth resistor R4 in series, wherein the second photoelectric coupler comprises a second light-emitting source U3A and a second light receiver U3B, the second light-emitting source U3A is connected with the fourth resistor R4, and the second light receiver U3B is connected with the power management chip U1. Preferably, the second light emitting source U3A is connected in parallel with the output filter capacitor C2 through a voltage regulator tube Z and a fourth resistor R4; one end of the second light receiver U3B is connected to the FB pin of the power management chip U1, and the other end is grounded, so that the detected battery voltage value is transmitted to the power management chip U1.
The arrangement of the battery detection circuit ensures that the utility model not only can charge the corresponding battery type products intelligently by the charger product, but also can reduce the probability of the products being mistakenly used; the method can also identify whether the battery has over-discharge condition under the condition of not using the MCU and not communicating, and the charger will not charge the battery if the battery is over-discharged, thereby playing a certain safety protection role.
When a battery or other external power supply is connected to the switching power supply starting circuit, a voltage higher than 22V is applied to BAT + and GND (the lowest 22V is taken as an example here for explanation, theoretically, the circuit of the utility model can work on any voltage occasion higher than 2.5V), at this moment, the voltage makes the first photoelectric coupler electrified after passing through the resistor R3, the first light-emitting source U2A starts working, the internal light-emitting tube emits light, and the first light-receiving device U2B is conducted; then, the first starting resistor R1 and the second starting resistor R2 are connected into the circuit, the whole starting circuit is conducted, and the VDD pin of the power management chip U1 obtains an initial starting voltage and starts to work; then, the power management chip U1 outputs a control signal to the fet Q1 through a Gate pin, and controls the fet Q1 to be turned on, so that the transformer T1 starts to operate, and outputs the output voltage of the rectifying and smoothing circuit for charging.
When the switching power supply starting circuit works normally, the battery detection circuit detects the output voltage value of the battery in real time so as to control the transformer T1 to be started or shut down in real time according to the detected voltage value. That is, when the battery detection circuit detects that the voltage at the output rectifying and filtering circuit is normally output, an isolation signal is sent to the power management chip U1 and the feedback circuit, and the power management chip U1 controls the transformer T1 to be normally conducted to continue supplying power; when the battery detection circuit detects that no voltage output exists at the output rectifying filter circuit, an isolation signal is sent to the power management chip U1 and the feedback circuit, at the moment, the power management chip U1 cuts off the field effect transistor Q1, the transformer T1 stops working, and at the moment, the whole switching power supply starting circuit enters a standby state (namely a closed state) to play a certain safety protection role.
Of course, when the battery or other external power source is removed, the levels at the two ends of the BTA + and the GND disappear, the first photocoupler stops working, the first light emitting source U2A stops emitting light, the first light receiver U2B is cut off, the VDD pin power supply circuit of the power management chip U1 is completely cut off, the power management chip U1 is powered off and stops working, at this time, the whole switching power supply starting circuit enters a closed state (i.e., a standby state), all chips for controlling the circuit to work stop working (a non-sleep mode), and at this time, the power consumption of the switching power supply starting circuit is zero.
To sum up, the switching power supply starting circuit of the present invention utilizes the first photoelectric coupler (U2A, U2B) to drive the power management chip U1 to start and stop, when the first photoelectric coupler (U2A, U2B) is powered on, the starting circuit is turned on, and the power management chip U1 and the transformer T1 start and work; when the first photocoupler (U2A, U2B) is powered off, the power management chip U1 stops working and enters a standby state, and the standby power consumption of the power management chip U1 is equal to zero.
Compared with the prior art, the utility model discloses a zero-power consumption under the realization standby mode that switching power supply starting circuit can be real has reduced the unnecessary wasting of resources. Furthermore, the utility model discloses solution charger product that can be fine is the problem of stand-by power consumption under the condition of not having load, simultaneously can also effectually prevent that the charger product from nevertheless not using time again at long-term circular telegram, and the product life that stand-by work leads to reduces, and the life of multiplicable product has effectively improved the security and the operational reliability of product.
The above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present invention can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present invention.
Claims (10)
1. A switching power supply startup circuit, comprising:
the input end of the input rectifying filter circuit is connected with an alternating current power supply;
the input end of the starting circuit is connected with the output end of the input rectifying and filtering circuit;
the transformer comprises a primary coil, a secondary coil and a feedback coil, wherein the primary coil is arranged on one side of the transformer and connected with the output end of the input rectifying and filtering circuit, and the secondary coil is arranged on the other side of the transformer;
the input end of the output rectifying filter circuit is connected with the secondary coil of the transformer;
the input end of the feedback circuit is connected with the feedback coil, and the input end of the feedback circuit is also connected with the output end of the output rectifying and filtering circuit;
the first photoelectric coupler is respectively connected with the output end of the starting circuit and an external battery; and
the power management chip is respectively connected with the output end of the first photoelectric coupler, the output end of the feedback circuit and the primary coil of the transformer;
after the first photoelectric coupler is electrified, the starting circuit is conducted, and the power management chip and the transformer are started and work; after the first photoelectric coupler is powered off, the power management chip stops working and enters a standby state, and at the moment, the standby power consumption of the power management chip is equal to zero.
2. The switching power supply startup circuit according to claim 1, wherein: the first photoelectric coupler comprises a first light emitting source and a first light receiver, the first light emitting source is connected with the anode of an external battery, one end of the first light receiver is connected with the output end of the starting circuit, the other end of the first light receiver is connected with the power management chip, and after the first light emitting source is electrified, the first light receiver outputs voltage to enable the starting circuit to be conducted with the power management chip.
3. The switching power supply startup circuit according to claim 2, wherein: the starting circuit comprises at least one starting resistor connected between the output end of the input rectifying and filtering circuit and the first light receiver.
4. The switching power supply startup circuit according to claim 1, wherein: the output rectifying and filtering circuit comprises a diode and an output filtering capacitor, wherein the diode and the output filtering capacitor are connected with a secondary coil of the transformer, the diode is connected with the secondary coil in series, and the output filtering capacitor is connected with the secondary coil in parallel.
5. The switching power supply startup circuit according to claim 1, wherein: the feedback circuit comprises a direct current negative feedback resistor and a reverse cut-off rectifier tube, wherein one end of the direct current negative feedback resistor is connected with the feedback coil, the other end of the direct current negative feedback resistor is connected with the power management chip, one end of the reverse cut-off rectifier tube is connected with the feedback coil, the other end of the reverse cut-off rectifier tube is connected with the first photoelectric coupler, and the direct current negative feedback resistor is connected with a CS (circuit switching) pin of.
6. The switching power supply startup circuit according to claim 1, wherein: the switch power supply starting circuit further comprises a switch device connected between the power supply management chip and the transformer, and the switch device is used for controlling the transformer to be started or shut down according to the control signal output by the power supply management chip.
7. The switching power supply startup circuit of claim 6, wherein: the switch device is a field effect transistor, a grid electrode of the field effect transistor is connected with a Gate pin of the power management chip, a drain electrode of the field effect transistor is connected with a primary coil of the transformer, a source electrode of the field effect transistor is grounded, a parasitic diode is connected between the source electrode and the drain electrode of the field effect transistor, and the parasitic diode is conducted in a one-way mode in the direction from the source electrode to the drain electrode.
8. The switching power supply startup circuit according to claim 1, wherein: the switching power supply starting circuit further comprises a battery detection circuit, the battery detection circuit comprises a voltage-regulator tube connected with the output rectifying and filtering circuit, a fourth resistor connected with the voltage-regulator tube in series and a second photoelectric coupler connected with the fourth resistor in series, the second photoelectric coupler comprises a second light-emitting source and a second light receiver, the second light-emitting source is connected with the fourth resistor, and the second light receiver is connected with the power supply management chip.
9. The switching power supply startup circuit of claim 8, wherein: and one end of a second light receiver of the second photoelectric coupler is connected with the FB pin of the power management chip, and the other end of the second light receiver is grounded.
10. The switching power supply startup circuit according to claim 1, wherein: the power management chip is also provided with an RT pin which is grounded through a timing resistor.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021434855.2U CN212343641U (en) | 2020-07-20 | 2020-07-20 | Switch power supply starting circuit |
| EP21184300.8A EP3944479A1 (en) | 2020-07-20 | 2021-07-07 | Starting circuit of switching power supply |
| US17/368,831 US11502598B2 (en) | 2020-07-20 | 2021-07-07 | Starting circuit of switching power supply |
| AU2021204990A AU2021204990A1 (en) | 2020-07-20 | 2021-07-12 | Starting circuit of switching power supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021434855.2U CN212343641U (en) | 2020-07-20 | 2020-07-20 | Switch power supply starting circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN212343641U true CN212343641U (en) | 2021-01-12 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202021434855.2U Active CN212343641U (en) | 2020-07-20 | 2020-07-20 | Switch power supply starting circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN212343641U (en) |
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2020
- 2020-07-20 CN CN202021434855.2U patent/CN212343641U/en active Active
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