CN210273865U - Synchronous rectification circuit of charger - Google Patents
Synchronous rectification circuit of charger Download PDFInfo
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- CN210273865U CN210273865U CN201921309150.5U CN201921309150U CN210273865U CN 210273865 U CN210273865 U CN 210273865U CN 201921309150 U CN201921309150 U CN 201921309150U CN 210273865 U CN210273865 U CN 210273865U
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Abstract
The utility model relates to the technical field of circuits, in particular to a synchronous rectification circuit of a charger, which comprises a transformer, wherein the primary side of the transformer transmits electric quantity to the secondary side of the transformer to generate high-frequency square waves; and the input end of the synchronous rectification module is connected with the secondary side of the transformer, and the output end of the synchronous rectification module is connected with the anode of the external battery and used for controlling the high-frequency square waves to be output to the external battery for power supply through synchronous rectification. The technical scheme of the utility model beneficial effect lies in: through connecting external battery to for synchronous rectifier circuit power supply, need not additionally to increase supply circuit, through synchronous rectifier module, the voltage of external battery is low excessively, causes under the not enough condition of supply voltage, makes synchronous rectifier circuit continue normal work, with the reduction power loss, thereby reduces heat dissipation device cost.
Description
Technical Field
The utility model relates to the technical field of circuits, especially, relate to a synchronous rectification circuit of charger.
Background
The storage battery charger organically combines a high-frequency switching power supply technology and an embedded microcomputer control technology, and utilizes an intelligent dynamic adjustment technology to realize optimization of a charging characteristic curve and effectively prolong the service life of a storage battery. The device adopts a constant-current/constant-voltage/small constant-current charging mode in multiple stages, and has the characteristics of high reliability, simplicity and convenience in operation, light weight, small size and the like. In order to facilitate users and save resources, intelligent chargers compatible with 6V/12V storage batteries appear on the market. The intelligent charger can be intelligently matched with storage batteries with different voltages of 6V or 12V through detection of an MCU (micro control unit). In order to reduce the cost, it is currently common practice to use schottky diodes for the main output, and after rectification and filtering, the schottky diodes generate a supply voltage of usually 15V or more at the minimum.
In the existing 6V/12V intelligent charger power supply, a Schottky diode is used as a main output in a common method, and a power supply voltage above 15V is generated after rectification and filtering. Because the charging voltage of the 6V storage battery is lower, the working voltage of the circuit is also lower, the conduction voltage drop of the rectifier diode is higher under the condition of low voltage and large current output, and the loss of the rectifier tube at the output end is particularly prominent. The Fast Recovery Diode (FRD) or the ultrafast recovery diode (SRD) may reach 1.0-1.2V, and a voltage drop of about 0.6V may be generated even if a low-voltage-drop schottky diode (SBD) is used, which may cause an increase in rectification loss and a decrease in power efficiency. Therefore, the above problems are difficult problems to be solved by those skilled in the art.
Disclosure of Invention
In view of the above problems in the prior art, a synchronous rectification circuit of a charger is provided to reduce power loss. The specific technical scheme is as follows:
the utility model provides a synchronous rectifier circuit of charger connects an external battery, wherein, include:
the primary side of the transformer transmits electric quantity to the secondary side of the transformer so as to generate high-frequency square waves;
and the input end of the synchronous rectification module is connected with the secondary side of the transformer, and the output end of the synchronous rectification module is connected with the anode of the external battery and is used for controlling the high-frequency square waves to be output to the external battery for supplying power through synchronous rectification.
Preferably, the synchronous rectification module includes:
a power supply pin of the synchronous rectification control chip is connected with the anode of the external battery, an analog grounding pin of the synchronous rectification control chip is connected with the cathode of the external battery, and a shell grounding pin of the synchronous rectification control chip is connected with the cathode of the external battery;
the grid electrode of the switch tube is connected with an enabling pin of the synchronous rectification control chip, the drain electrode of the switch tube is connected with the secondary side of the transformer, and the source electrode of the switch tube is connected with the negative electrode of the external battery;
and the anode of the diode is connected to the source electrode of the switch tube, and the cathode of the diode is connected to the drain electrode of the switch tube.
Preferably, the synchronous rectification module further includes a current limiting resistor, and the current limiting resistor is connected between the detection pin of the synchronous rectification control chip and the drain of the switching tube.
Preferably, the synchronous rectification module further includes a filter capacitor, an anode of the filter capacitor is connected to a power pin of the synchronous rectification control chip, and a cathode of the filter capacitor is connected to a cathode of the external battery.
Preferably, the transformer is a high frequency transformer.
Preferably, the switch tube is a field effect tube.
Preferably, the diode is a rectifier diode.
Preferably, the filter capacitor is a polar capacitor.
The technical scheme of the utility model beneficial effect lies in: through connecting external battery to for synchronous rectifier circuit power supply, need not additionally to increase supply circuit, through synchronous rectifier module, the voltage of external battery is low excessively, causes under the not enough condition of supply voltage, makes synchronous rectifier circuit continue normal work, with the reduction power loss, thereby reduces heat dissipation device cost.
Drawings
Embodiments of the present invention will now be described more fully hereinafter with reference to the accompanying drawings. The drawings are, however, to be regarded as illustrative and explanatory only and are not restrictive of the scope of the invention.
Fig. 1 is a circuit diagram of a synchronous rectification circuit according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.
It should be noted that, in the present invention, the embodiments and features of the embodiments may be combined with each other without conflict.
The present invention will be further described with reference to the accompanying drawings and specific embodiments, but the present invention is not limited thereto.
The utility model provides a synchronous rectifier circuit of charger, wherein, include:
the primary side of the transformer T transmits electric quantity to the secondary side of the transformer T to generate high-frequency square waves;
and the input end of the synchronous rectification module 1 is connected with the secondary side of the transformer T, and the output end of the synchronous rectification module 1 is connected with the anode of the external battery Batt and is used for controlling the high-frequency square wave to be output to the external battery Batt for power supply through synchronous rectification.
The transformer T is a high frequency transformer.
With the synchronous rectification circuit, as shown in fig. 1, the transformer T is a high-frequency transformer, and the electric quantity of the primary side of the transformer T is converted and coupled to the secondary side of the transformer T through a switch to generate a high-frequency square wave.
Further, alternating current voltage in the transformer T is rectified into direct current voltage through the synchronous rectification module 1, after filtering processing is carried out, power is supplied to an external battery Batt, a power supply circuit does not need to be additionally arranged, and under the condition that the voltage of the external battery is too low and the power supply voltage is insufficient, the synchronous rectification circuit can continuously and normally work through the synchronous rectification module 1, so that power loss is reduced, and the cost of a heat dissipation device is reduced.
In a preferred embodiment, the synchronous rectification module 1 comprises:
a power supply pin VDD of the synchronous rectification control chip U is connected with the positive electrode of the external battery Batt, an analog grounding pin AGND of the synchronous rectification control chip U is connected with the negative electrode of the external battery Batt, and a shell grounding pin PGND of the synchronous rectification control chip U is connected with the negative electrode of the external battery Batt;
the grid electrode of the switching tube Q is connected with an enabling pin SYNC of the synchronous rectification control chip U, the drain electrode of the switching tube Q is connected with the secondary side of the transformer T, and the source electrode of the switching tube Q is connected with the negative electrode of the external battery Batt;
and the anode of the diode D is connected to the source electrode of the switching tube Q, and the cathode of the diode D is connected to the drain electrode of the switching tube Q.
The synchronous rectification module 1 further includes a current-limiting resistor R connected between the detection pin VDET of the synchronous rectification chip U and the drain of the switching tube Q.
The synchronous rectification module 1 further comprises a filter capacitor E, an anode of the filter capacitor E is connected to a power pin VDD of the synchronous rectification control chip U, and a cathode of the filter capacitor E is connected to a cathode of an external battery Batt.
Specifically, the synchronous rectification control chip U in the synchronous rectification module 1 may adopt chips of different models, where the model of the synchronous rectification control chip U in this embodiment is ME8415, the synchronous rectification control chip U includes five pins, which are a power supply pin VDD, an analog ground pin AGND, a case ground pin PGND, and an enable pin SYNC, respectively, where the power supply pin VDD is connected to an anode of an external battery Batt to supply power to the synchronous rectification control chip U through the external battery Batt, and the analog ground pin AGND and the case ground pin PGND are respectively connected to a cathode of the external battery Batt to protect the synchronous rectification circuit to normally operate.
Further, the gate of the switching tube Q is connected to an enable pin SYNC of the synchronous rectification control chip U, the drain of the switching tube Q is connected to the secondary side of the transformer T, and the source of the switching tube Q is connected to the negative electrode of the external battery Batt, so as to control the switching-on or switching-off of the switching tube Q through the enable pin SYNC.
Further, the voltage of the switching tube Q is detected through a current limiting resistor R connected between a detection pin VDET of the synchronous rectification control chip U and the drain of the switching tube Q and the detection pin VDET.
Further, a diode D is connected in parallel with the switching tube Q, that is, the anode of the diode D is connected to the source of the switching tube Q, and the cathode of the diode D is connected to the drain of the switching tube Q, when the voltage of the external battery Batt is too low (for example, the voltage of the external battery Batt is below 6V), the synchronous rectification control chip U may be powered insufficiently and cannot work normally, so that the switching tube Q cannot work normally, and at this time, the normal operation of the synchronous rectification circuit can be maintained by adding one diode D, which is described in detail in the following example in this embodiment:
if a Schottky diode is adopted for rectification and the conduction voltage drop is 0.6V, the rectification loss is as follows: 10A 0.6V ═ 6W; and adopt synchronous rectification, select for use and conduct impedance about 10m omega's switching tube Q, then the rectification loss is: 10A 0.01 Ω 1W, power loss of about 5W can be saved. Therefore, by the comparison, when the voltage of the external battery Batt is too low, the charging current can be set to be half or less by adding a diode D when the charger is charged below a certain voltage (e.g., 6V) to reduce the rectifying loss, and the normal charging current is set after the charging voltage rises with the charging of the battery and reaches the operating voltage of the synchronous rectifying control chip U.
In addition, through actual test comparison, the 120W charger can save power loss by more than 4W and improve conversion efficiency by more than 3 percentage points.
Further, since power loss is reduced, heat dissipation requirements are reduced, and the cost of the heat dissipation device can be reduced, the overall material cost is not increased or is increased little.
Further, the synchronous rectification module 1 further includes a filter capacitor E, an anode of the filter capacitor E is connected to the power pin VDD of the synchronous rectification control chip U, and a cathode of the filter capacitor E is connected to a cathode of the external battery Batt, so as to filter the dc voltage after rectifying the ac voltage in the transformer T into the dc voltage through the switch tube Q or the diode D, and further charge the external battery Batt.
In a preferred embodiment, the switching transistor Q is a field effect transistor.
In a preferred embodiment, the diode D is a rectifier diode.
In a preferred embodiment, the filter capacitor E is a polar capacitor.
The technical scheme of the utility model beneficial effect lies in: through connecting external battery to for synchronous rectifier circuit power supply, need not additionally to increase supply circuit, through synchronous rectifier module, the voltage of external battery is low excessively, causes under the not enough condition of supply voltage, makes synchronous rectifier circuit continue normal work, with the reduction power loss, thereby reduces heat dissipation device cost.
The above description is only an example of the preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and those skilled in the art should be able to realize the equivalent alternatives and obvious variations of the present invention.
Claims (8)
1. A synchronous rectification circuit of a charger, which is connected with an external battery, is characterized by comprising:
the primary side of the transformer transmits electric quantity to the secondary side of the transformer;
and the input end of the synchronous rectification module is connected with the secondary side of the transformer, and the output end of the synchronous rectification module is connected with the anode of the external battery.
2. The synchronous rectification circuit of the charger according to claim 1, wherein the synchronous rectification module comprises:
a power supply pin of the synchronous rectification control chip is connected with the anode of the external battery, an analog grounding pin of the synchronous rectification control chip is connected with the cathode of the external battery, and a shell grounding pin of the synchronous rectification control chip is connected with the cathode of the external battery;
the grid electrode of the switch tube is connected with an enabling pin of the synchronous rectification control chip, the drain electrode of the switch tube is connected with the secondary side of the transformer, and the source electrode of the switch tube is connected with the negative electrode of the external battery;
and the anode of the diode is connected to the source electrode of the switch tube, and the cathode of the diode is connected to the drain electrode of the switch tube.
3. The synchronous rectification circuit of the charger according to claim 2, wherein the synchronous rectification module further comprises a current limiting resistor, and the current limiting resistor is connected between the detection pin of the synchronous rectification control chip and the drain of the switching tube.
4. The synchronous rectification circuit of the charger according to claim 2, wherein the synchronous rectification module further comprises a filter capacitor, an anode of the filter capacitor is connected to a power supply pin of the synchronous rectification control chip, and a cathode of the filter capacitor is connected to a cathode of the external battery.
5. The synchronous rectification circuit of a charger according to claim 1, wherein said transformer is a high frequency transformer.
6. The synchronous rectification circuit of a charger according to claim 2, wherein the switching transistor is a field effect transistor.
7. The synchronous rectification circuit of a charger according to claim 2, wherein the diode is a rectifying diode.
8. The synchronous rectification circuit of the charger according to claim 4, wherein the filter capacitor is a polar capacitor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921309150.5U CN210273865U (en) | 2019-08-13 | 2019-08-13 | Synchronous rectification circuit of charger |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921309150.5U CN210273865U (en) | 2019-08-13 | 2019-08-13 | Synchronous rectification circuit of charger |
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| CN210273865U true CN210273865U (en) | 2020-04-07 |
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| CN201921309150.5U Active CN210273865U (en) | 2019-08-13 | 2019-08-13 | Synchronous rectification circuit of charger |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110429833A (en) * | 2019-08-13 | 2019-11-08 | 纽福克斯光电科技（上海）有限公司 | A kind of circuit of synchronous rectification of charger |
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2019
- 2019-08-13 CN CN201921309150.5U patent/CN210273865U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110429833A (en) * | 2019-08-13 | 2019-11-08 | 纽福克斯光电科技（上海）有限公司 | A kind of circuit of synchronous rectification of charger |
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