CN201898443U

CN201898443U - Alternating-current/direct-current power supply

Info

Publication number: CN201898443U
Application number: CN2010206152363U
Authority: CN
Inventors: 廖永波; 周全芳; 胡滨
Original assignee: LESHAN HONGTAI VOCATIONAL SKILLS TRAINING SCHOOL
Current assignee: LESHAN HONGTAI VOCATIONAL SKILLS TRAINING SCHOOL
Priority date: 2010-11-19
Filing date: 2010-11-19
Publication date: 2011-07-13
Anticipated expiration: 2020-11-19

Abstract

An alternating-current/direct-current power supply relates to electronics, and comprises a direct current branch and an alternating current branch. The direct current branch and the alternating current branch are connected to a direct-current voltage converter. The direct current branch includes a direct-current power input unit and a first isolation circuit, the direct-current power input unit is connected to a direct-current voltage converter through the first isolation circuit, and a control end of the first isolation circuit is connected to the direct-current power input unit. The alternating current branch includes an alternating-current input unit, a switch power unit and a second isolation circuit, the alternating-current input unit is connected to the direct-current voltage converter through the switch power unit and the second isolation unit, and a control end of the second isolation circuit is connected to a switch power circuit. The alternating-current/direct-current power supply realizes alternating-current/direct-current power supplying, so that electric devices such as set-top boxes and the like can be used under different power supply conditions, and application range of the electric devices is widened.

Description

DC/AC power supply source

Technical field

The utility model relates to electronic technology.

Background technology

Existing power circuit supply power mode mainly contains: 1, adopt the electric main power supply; 2, by direct current supplys such as adapter or vehicle powers.With the set-top box is example, and along with continuous advancement in technology and development, the function that set-top box has is more and more, and the scope of application is also more and more wider, also more and more higher to the requirement of its power supply flexibility.We may use its rating function at home for example a set-top box, may use its multimedia function onboard again simultaneously.This just requires set-top box not only can power by electric main, also needs to power by vehicle-mounted 12V DC power supply.Existing set-top box is because supply power mode is single, and the scope of application is greatly affected greatly.

The utility model content

Technical problem to be solved in the utility model is, provides a kind of and both can power by electric main, again can be by the power circuit of low-voltage dc power supply power supply, with the scope of application of expansion household electrical appliance.

The technical scheme that the utility model solve the technical problem employing is, DC/AC power supply source is characterized in that, comprises direct current branch and exchanges branch road, and two branch roads are connected to DC voltage converter; Direct current branch comprises the DC power source input units and first buffer circuit, and DC power source input units is connected to DC voltage converter by first buffer circuit, and the control end of first buffer circuit is connected to DC power source input units; Exchange branch road and comprise AC power input unit, switching power supply and second buffer circuit, the AC power input unit is connected to DC voltage converter by the switching power supply and second buffer circuit; The control end of second buffer circuit is connected to switching power circuit.

The beneficial effects of the utility model are, have realized supplied by AC/DC electricity, and electrical equipment such as set-top box can be used under different conditions of power supply, have widened its scope of application.And exchanging the inputs of input and direct current does not need switch such as relay to switch, and reliability improves greatly, and implementation cost is less.No matter employing exchanges still direct current input of input, and the voltage of output all has very high precision, has satisfied job requirement.Power circuit of the present utility model, output voltage is converted to through variator, because the negative feedback adjustment of transducer, the direct voltage required precision that prime is imported can reduce, and is particularly suitable for the bigger direct current supplys of voltage fluctuation such as vehicle power.

Below in conjunction with the drawings and specific embodiments the utility model is further described.

Description of drawings

Fig. 1 is a circuit block diagram of the present utility model.

Fig. 2 is the circuit diagram of embodiment of the present utility model.

Embodiment

Referring to Fig. 1.The dotted arrow of Fig. 1 is represented control signal.

The utility model comprises the two-way input: direct current branch and the branch road that exchanges that the electric main input is provided that the DC power supply input is provided.The input of electric main obtains direct voltage after changing through Switching Power Supply, and this direct voltage is input to converter by second buffer circuit, and the input of DC power supply directly is input to converter by first buffer circuit.The direct voltage control that first buffer circuit and second buffer circuit are obtained after Switching Power Supply transforms by DC power supply input voltage and electric main respectively.

First buffer circuit has following function: when DC power supply does not have input, make between DC power supply input and the converter input and isolate, the two no current is flow through.When DC power supply has input, make DC power supply input and converter import between conducting, promptly electric current by the DC power supply inlet flow to converter.Second buffer circuit has similar function: when electric main does not have input, the input of Switching Power Supply output and converter is isolated.When electric main has input, make conducting between Switching Power Supply output and the converter input, promptly the direct voltage of Switching Power Supply output this moment is input to the converter input.

The direct voltage of DC power supply input or the direct voltage of electric main input after the Switching Power Supply conversion after the converter conversion, can obtain each required road voltage.First buffer circuit and second buffer circuit have such feature: isolation does not need extra circuit that it is controlled with the state of conducting, i.e. the isolation of first buffer circuit and conducting is by DC power supply input control; The isolation of second buffer circuit and conducting are by electric main input decision.

Embodiment: referring to Fig. 2.

Present embodiment is the set-top box power circuit, and (12V, 5V 3.3V), are the normal power voltage of set-top box to export 3 road voltages altogether.The embodiment circuit can adopt the electric main power supply, also can lean on vehicle-mounted 12V DC power supply.The two-way input is promptly arranged: DC power supply input: DC_IN and electric main input: AC_IN.Thyratron TRIAC1, resistance R 15, voltage-stabiliser tube D7 and thyratron TRIAC2, resistance R 9, voltage-stabiliser tube D3 have formed two groups of controlled buffer circuits respectively, and promptly the original paper in frame of broken lines 2 and the frame of broken lines 3 has constituted first buffer circuit and second buffer circuit.DC converter DC/DC1 and DC/DC2 and peripheral circuit thereof have been formed the DC voltage converter among Fig. 1, i.e. the circuit that comprised of frame of broken lines 4 and frame of broken lines 5.Switching Power Supply has been formed in Switching Power Supply control chip OB2353 and the periphery thereof of IC1, i.e. the circuit that comprised of frame of broken lines 1.

Now the course of work to circuit is described as follows: when this set-top box power circuit has only alternating current input, when promptly power by electric main, not conducting of thyratron TRIAC1, the DC_IN input port with back level isolation.Alternating current obtains direct voltage after the rectifier bridge rectification, be input to primary NP after capacitor C 1 filtering, and filtered DC bus-bar voltage is powered for the IC1 inner drive by resistance R 1, R2, R3, R4 and capacitor C 2 and starting resistor is provided.Capacitor C 4, diode D01 and resistance R 5, R6 have formed reed position circuit, and the direct voltage that prevents to be input to primary is too high, and circuit is caused damage.Transformer biasing winding ND is chip OB2353 power supply after diode D02 rectification.Transformer secondary output NS output obtains direct voltage VCC through diode D1 rectification after capacitor C 6, C7 and inductance L 1 filtering, and feedback loop has been formed in optocoupler OP1 and three ends adjustable shunting a reference source TL431 and periphery thereof, makes voltage VCC keep stable.Because VCC is a direct voltage, VCC is about 12V herein, this moment, thyratron TRIAC2 was with conducting, ignore the pressure drop of thyratron TRIAC2, VCC will be input to converter DC/DC1 and DC/DC2, and directly export the 12V power supply (in this example, set-top box 12V power reguirements precision is not high) as set-top box, by the feedback loop of rational design Transformer Winding and Switching Power Supply, can make this road output of 12V be stabilized in zone of reasonableness.Converter DC/DC1 and DC/DC2 are required 5V and 3.3V voltage with the dc voltage conversion of input.Owing to have negative feedback, 5V and 3.3V output have very high precision.

When set-top box adopted direct current supply, promptly DC_IN was input as 12V, and electric main does not have input, this moment the transformer secondary output no-output, i.e. VCC no-voltage, not conducting of thyratron TRIAC2, VCC isolates with the back level.Voltage-stabiliser tube D7 clamper is a high level, thyratron TRIAC1 conducting, be input to converter DC/DC1 and DC/DC2 behind the 12V voltage process diode D8 of DC_IN input, and directly output is as the 12V power supply of set-top box, D8 selects the Schottky diode of low pressure drop for use herein, so that the 12V of set-top box power supply is unlikely to fall too lowly.Converter DC/DC1 and DC/DC2 are converted to required 5V of set-top box and 3.3V with the direct voltage of input, because degenerative adjustment, this two-way output accuracy is higher, can bear bigger input voltage fluctuation simultaneously.

In this example, a kind of like this extreme case may occur, promptly electric main and direct current supply port are simultaneously by input, and diode D8 can prevent that the output of Switching Power Supply from impacting to the direct-flow input end mouth.

Claims

1. DC/AC power supply source is characterized in that, comprises direct current branch and exchanges branch road, and two branch roads are connected to DC voltage converter; Direct current branch comprises the DC power source input units and first buffer circuit, and DC power source input units is connected to DC voltage converter by first buffer circuit, and the control end of first buffer circuit is connected to DC power source input units; Exchange branch road and comprise AC power input unit, switching power supply and second buffer circuit, the AC power input unit is connected to DC voltage converter by the switching power supply and second buffer circuit; The control end of second buffer circuit is connected to switching power circuit.

2. DC/AC power supply source as claimed in claim 1 is characterized in that described DC voltage converter has the output of different output voltages.