CN212085883U - Automatic power supply switching circuit - Google Patents
Automatic power supply switching circuit Download PDFInfo
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- CN212085883U CN212085883U CN202021012286.2U CN202021012286U CN212085883U CN 212085883 U CN212085883 U CN 212085883U CN 202021012286 U CN202021012286 U CN 202021012286U CN 212085883 U CN212085883 U CN 212085883U
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Abstract
The utility model discloses a power automatic switch-over circuit, include: the power supply comprises a lithium battery VBAT, an external power supply input interface J1, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a capacitor C1, a capacitor C2, a capacitor E1, a triode Q1, a triode Q2, a triode Q3, a diode D1, a diode D2 and a power supply output interface P1. The automatic power supply switching circuit can realize the switching from the power supply of the lithium battery to the power supply of an external power supply by controlling the state of the triode Q3.
Description
Technical Field
The utility model relates to a circuit structure field provides a power automatic switch-over circuit very much.
Background
Present mobile terminal equipment uses lithium battery power supply mostly, and the condition that lithium battery electric quantity is not enough often can appear in the equipment in the use, if not in time change power supply this moment, will lead to mobile device not arrive the destination before close with regard to the low pressure to lead to data loss, in addition, if when discovering the lithium battery electric quantity not enough, direct access external power source realizes the power supply and charges to the battery bipolar very dangerous.
Therefore, it is necessary to design a circuit to automatically switch from the lithium battery power supply state to the external power supply state when the external power supply is connected.
SUMMERY OF THE UTILITY MODEL
In view of this, the utility model aims at providing a power automatic switch-over circuit to realize converting external power supply state into from lithium battery power supply state when inserting external power supply automatically, avoid the danger of direct access external power supply to the battery two poles of the earth, realize the seamless switching of lithium battery power supply and external power supply.
The utility model provides a technical scheme is: an automatic power switching circuit comprising: lithium battery VBAT, external power input interface J, resistor R, capacitor C, capacitor E, triode Q, diode D and power output interface P, wherein pin 1 of the external power input interface J is connected with the base electrode of the triode Q through resistor R and is connected with the collector electrode of the triode Q through diode D, the positive input end of the lithium battery VBAT is connected with the emitter electrode of the triode Q, the resistor R is connected between the emitter electrode and the base electrode of the triode Q in parallel, the base electrode of the triode Q is connected with the emitter electrode of the triode Q, the collector electrode of the triode Q is connected with the positive electrode of the power output interface, the positive input end of the lithium battery VBAT is connected with the emitter electrode of the triode Q through resistor R, the emitter electrode of the triode Q is connected with the base electrode of the triode Q through resistor R, the base electrode of the triode Q is connected with the collector, the capacitor C1, the capacitor C2, the diode D2 and the capacitor E1 are connected in parallel between the collector of the triode Q3 and the collector of the triode Q1, and the collector of the triode Q1, the collector of the triode Q2, the pin 2 and the pin 3 of the external power input interface J1, the negative electrode of the lithium battery VBAT and the negative electrode of the power output interface P1 are connected.
The utility model provides a power automatic switch-over circuit can realize the seamless switching function of lithium cell power supply and external power supply through the state of control triode, when not having external power supply to insert, uses lithium cell power supply, and when external power supply inserts, uses the external power supply. In addition, because the on-resistance of the transistor Q3 is extremely small, the voltage drop of the transistor during power supply is very small, and the voltage drop can be basically consistent with the output of the battery, and the circuit can realize the preferential power supply of an external power supply.
Drawings
The present invention will be described in further detail with reference to the accompanying drawings and embodiments:
fig. 1 is a circuit diagram of the power supply automatic switching circuit provided by the present invention.
Detailed Description
As shown in fig. 1, the utility model provides a power automatic switching circuit, include: lithium battery VBAT, external power input interface J, resistor R, capacitor C, capacitor E, triode Q, diode D and power output interface P, wherein pin 1 of the external power input interface J is connected with the base electrode of the triode Q through resistor R and is connected with the collector electrode of the triode Q through diode D, the positive input end of the lithium battery VBAT is connected with the emitter electrode of the triode Q, the resistor R is connected between the emitter electrode and the base electrode of the triode Q in parallel, the base electrode of the triode Q is connected with the emitter electrode of the triode Q, the collector electrode of the triode Q is connected with the positive electrode of the power output interface, the positive input end of the lithium battery VBAT is connected with the emitter electrode of the triode Q through resistor R, the emitter electrode of the triode Q is connected with the base electrode of the triode Q through resistor R, the base electrode of the triode Q is connected with the collector, the capacitor C1, the capacitor C2, the diode D2 and the capacitor E1 are connected in parallel between the collector of the triode Q3 and the collector of the triode Q1, and the collector of the triode Q1, the collector of the triode Q2, the pin 2 and the pin 3 of the external power input interface J1, the negative electrode of the lithium battery VBAT and the negative electrode of the power output interface P1 are connected.
The principle of the power supply automatic switching circuit is as follows: when the external power supply is not input, the base voltage of the triode Q2 is 0V, the triode Q2 is not conducted, the voltage of the lithium battery VBAT is divided by the resistors R2, R3 and R4 to generate a voltage drop larger than 0.7V at the base of the triode Q1, the triode Q1 is conducted, the base of the triode Q3 is 0V, the triode Q3 is conducted, the voltage output by the positive pole of the lithium battery VBAT is supplied to the positive pole of the power output interface through the collector of the triode Q3, when the external power supply is input, and the external power supply input is larger than 1V, the voltage drop of 0.7V is generated on the base electrode of the triode Q2, the triode Q2 is conducted, the base electrode voltage of the triode Q1 is 0V, the triode Q1 is cut off, the base electrode of the triode Q3 is at a high level, the triode Q3 is cut off, the VBAT output of the lithium battery is disconnected and is not powered, the external power supply supplies power for the positive electrode of the power output interface through the output voltage of the diode D1, and the power supply state of the lithium battery is automatically converted into the power supply state of the external power supply when the external power supply is connected.
Claims (1)
1. An automatic power switching circuit, comprising: lithium battery VBAT, external power input interface J, resistor R, capacitor C, capacitor E, triode Q, diode D and power output interface P, wherein pin 1 of the external power input interface J is connected with the base electrode of the triode Q through resistor R and is connected with the collector electrode of the triode Q through diode D, the positive input end of the lithium battery VBAT is connected with the emitter electrode of the triode Q, the resistor R is connected between the emitter electrode and the base electrode of the triode Q in parallel, the base electrode of the triode Q is connected with the emitter electrode of the triode Q, the collector electrode of the triode Q is connected with the positive electrode of the power output interface, the positive input end of the lithium battery VBAT is connected with the emitter electrode of the triode Q through resistor R, the emitter electrode of the triode Q is connected with the base electrode of the triode Q through resistor R, the base electrode of the triode Q is connected with the collector, the capacitor C1, the capacitor C2, the diode D2 and the capacitor E1 are connected in parallel between the collector of the triode Q3 and the collector of the triode Q1, and the collector of the triode Q1, the collector of the triode Q2, the pin 2 and the pin 3 of the external power input interface J1, the negative electrode of the lithium battery VBAT and the negative electrode of the power output interface P1 are connected.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021012286.2U CN212085883U (en) | 2020-06-05 | 2020-06-05 | Automatic power supply switching circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021012286.2U CN212085883U (en) | 2020-06-05 | 2020-06-05 | Automatic power supply switching circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN212085883U true CN212085883U (en) | 2020-12-04 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202021012286.2U Active CN212085883U (en) | 2020-06-05 | 2020-06-05 | Automatic power supply switching circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN212085883U (en) |
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2020
- 2020-06-05 CN CN202021012286.2U patent/CN212085883U/en active Active
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