CN201440615U

CN201440615U - AC power-off quick response and AC filtering capacitance discharging circuit

Info

Publication number: CN201440615U
Application number: CN2009201937618U
Authority: CN
Inventors: 左德祥; 张成顺
Original assignee: HUIZHOU SANHUA INDUSTRIAL Ltd
Current assignee: HUIZHOU SANHUA INDUSTRIAL Ltd
Priority date: 2009-08-27
Filing date: 2009-08-27
Publication date: 2010-04-21
Anticipated expiration: 2019-08-27

Abstract

The utility model relates to an AC power-off quick response and AC filtering capacitance discharging circuit. The discharging circuit comprises an MOS pipe Q14, an MOS pipe Q13 and a resistor R4. The MOS pipe Q14 is connected with a PWM control chip power supply foot, the MOS pipe Q13 is connected with a PWM adjusting foot, and the resistor R4 is connected with a high-voltage starting foot. The other end of the resistor R4 is respectively connected to input ends L2 and N2 of an AC power supply by a diode. A signal AC of the AC power supply is sequentially connected with grid electrodes of the two MOS pipes by a signal shaping circuit and a control circuit, so as to realize control of the two MOS pipes, thereby realizing control of the PWM control chip. When the external AC power supply is off, the discharging circuit can quickly release electric quantity in AC filtering capacitance in a power supply circuit and quickly restrain the working of a PWM pulse generating chip so as to stop supplying power for other function circuits in an electronic product; moreover, the discharging circuit can effectively avoid the problems that a working time sequence of an entire machine can be easily in disorder and the product cannot normally work when the time interval between power off and on is short.

Description

A kind of AC dump is response and ac filter capacitor discharging circuit fast

Technical field

The utility model relates to the electronic product power technology, is meant that specifically a kind of AC dump that is applied to the electronic product power unit responds and ac filter capacitance discharges circuit fast.

Background technology

The electric equipment products of various use AC power, when closing AC power, because the energy storage effect of appliances power source internal capacitance, work really long days is partly understood in the standby of power supply, to such an extent as to power supply indicator can not extinguish for a long time, brings inconvenience to the user.As shown in Figure 1, be existing flat-plate television power supply standby partial circuit block diagram.When AC power is turn-offed, because the energy storage effect of storage capacitor C1, the auxiliary power supply end VCC ' of stand-by circuit part continues power supply to pwm chip, pwm chip can work in for a long time, if power on again in the short time, like this from power down to the time interval that powers on more in short-term, cause complete machine work schedule confusion easily, even cisco unity malfunction.

Under the situation of current energy scarcity, also more and more higher to various electronic product requirements of saving energy, so just require the stand-by power consumption of electronic product as far as possible little, the discharge resistance power consumption of ac filter capacitor C X1 in the flat-plate television power supply part, also be that restriction power supply stand-by power consumption is further done one of little reason, particularly (in＜0.1W) the power supply, the discharge resistance power consumption of ac filter capacitor C X1 more can not be ignored at ultralow stand-by power consumption.

The utility model content

The utility model be intended to solve in the above-mentioned electronic product behind the power-off since the storage capacitor discharge process cause the power unit continuous working period long, and the big problem of ac filter capacitor discharge resistance power consumption.

For addressing the above problem, the technical scheme that the utility model is taked is: a kind of AC dump is response and ac filter capacitor discharging circuit fast, be connected between AC power and the pwm chip, comprise connecting the metal-oxide-semiconductor Q14 that is used for storage capacitor C3 discharge, the metal-oxide-semiconductor Q13 that connects with pwm chip PWM adjusting pin and the resistance R 4 that connects with pwm chip high voltage startup pin respectively with the pwm chip supply pin, resistance R 4 other ends are connected to ac power input end L2 or N2 by diode respectively; Described ac supply signal AC connects metal-oxide-semiconductor Q14, Q13 grid by signal transformation circuit and control circuit successively to be realized the control of metal-oxide-semiconductor Q14, Q13 and then realizes control to pwm chip.

Described shaping circuit comprises triode Q11, and resistance and the diode of described triode Q11 base stage by series connection connects that AC signal end, collector electrode connect the pwm chip supply pin, emitter-base bandgap grading connects control circuit by capacitance C11 simultaneously by grounding through resistance.

Described control circuit comprises triode Q12 and is connected in capacitor C 12 between Q12 collector electrode and the ground; Triode Q12 collector electrode also connects metal-oxide-semiconductor Q14, Q13 grid, also connects the pwm chip supply pin by resistance in addition; Triode Q12 base stage connects capacitance C11 one end, emitter grounding by resistance.

The interface of described capacitance C11 and control circuit has also passed through the diode D13 ground connection of discharge process; Described metal-oxide-semiconductor Q14 drain electrode connects the supply pin of pwm chip by resistance; Triode Q11 base stage is passed through grounding through resistance in the described shaping circuit.

Circuit application described in the utility model is in electronic product power circuit part, when the disconnecting external AC power, described circuit can fast detecting go out the AC dump signal behind power operation, simultaneously the electric weight rapid release in the ac filter electric capacity is fallen, and suppress the work of pwm chip fast, make it stop other functional circuit power supply in electronic product, effectively avoid when power down to the time interval that powers on more in short-term, cause the problem of complete machine work schedule confusion product cisco unity malfunction easily.And the ingenious metal-oxide-semiconductor that uses when pwm chip is inner to be started that utilizes discharges to ac filter electric capacity in the power circuit, has reduced ac filter capacitance discharges power consumption, and electronic product complete machine stand-by power consumption is further reduced.

Description of drawings

Fig. 1 is existing flat-plate television power supply standby part one circuit block diagram;

Fig. 2 is existing another circuit block diagram of flat-plate television power supply standby part;

Fig. 3 is the utility model embodiment one circuit theory diagrams;

Fig. 4 is the utility model embodiment two circuit theory diagrams.

Embodiment

The utility model is described in further detail below in conjunction with drawings and Examples.

As Fig. 1 or shown in Figure 2, the general power conversion that adopts a pwm chip and transformer to obtain behind the AC power rectifying and wave-filtering of 220V of electronic product power unit stand-by circuit becomes to be suitable for the power supply of electronic product work in the prior art.When AC power is turn-offed, because the energy storage effect of storage capacitor C1, the auxiliary power supply end VCC ' meeting of stand-by circuit part continues power supply to the PWM chip, and the PWM chip can work in for a long time, to such an extent as to power supply indicator can not extinguish for a long time, brings inconvenience to the user.If power on again in the short time, like this from power down to the time interval that powers on more in short-term, cause complete machine work schedule confusion easily, even cisco unity malfunction.Simultaneously, in this power circuit, the power consumption that exchanges input filter capacitor CX1 discharge resistance is bigger, and the complete machine stand-by power consumption of electronic product can't further be reduced.

And circuit described in the utility model has well solved the problems referred to above.Be illustrated in figure 3 as the utility model embodiment one circuit theory diagrams.The pwm chip model is LD7575. in the present embodiment

Circuit described in the utility model is connected between AC power and the pwm chip, comprise connecting the metal-oxide-semiconductor Q14 that is used for storage capacitor C3 discharge, the metal-oxide-semiconductor Q13 that connects with pwm chip PWM adjusting pin COMP and the resistance R 4 that connects with pwm chip high voltage startup pin HV respectively with pwm chip supply pin VCC, resistance R 4 other ends are connected to ac power input end L2 and N2 or N2 and L2 respectively by diode D14, D15 respectively; Described ac supply signal AC connects metal-oxide-semiconductor Q14, Q13 grid by signal transformation circuit and control circuit successively to be realized the control of metal-oxide-semiconductor Q14, Q13 and then realizes control to pwm chip.Metal-oxide-semiconductor Q14, Q13 source ground.Described metal-oxide-semiconductor Q14 drain electrode connects the supply pin of pwm chip by resistance R 17.

Wherein, shaping circuit comprises triode Q11, resistance R 11 and the diode D11 of described triode Q11 base stage by series connection meets AC signal end AC, collector electrode and connects pwm chip supply pin, emitter-base bandgap grading by resistance R 13 ground connection, connects control circuit by capacitance C11 simultaneously.Be connected to diode D12 between triode Q11 collector electrode and base stage; Triode Q11 base stage is by resistance R 12 ground connection.

Described control circuit comprises triode Q12 and is connected in capacitor C 12 between Q12 collector electrode and the ground; Triode Q12 collector electrode also connects metal-oxide-semiconductor Q14, Q13 grid, also connects the pwm chip supply pin by resistance R 16 in addition; Triode Q12 base stage connects capacitance C11 one end, passes through resistance R 15 ground connection by resistance R 14; Triode Q12 emitter grounding.

The interface A of described capacitance C11 and control circuit has also passed through the diode D13 ground connection of discharge process.

Its operation principle is as follows: when the AC power normal power supply, and the pwm chip operate as normal, its supply pin power supply VCC gives capacitor C 12 chargings by resistance R 16 simultaneously.Diode D11 gathers ac supply signal AC, at the emitter-base bandgap grading output services frequency impulse wave identical with mains frequency of triode Q11, this impulse wave is by capacitance C11, resistance R 14, R15 and then control triode Q12 after the signal transformation circuit shaping that resistance R 11, R12, R13, diode D12 and triode Q11 form for this signal.When each positive pulse ripple, the Q12 conducting once, thereby give capacitor C 12 discharges once.Guarantee so not assemble high electric charge in the capacitor C 12, thus Q13, and not conducting of Q14 does not promptly influence PWM control iC operate as normal.

When AC dump, because the effect of capacitance C11, make triode Q12 stop conducting, and power supply VCC continues to give capacitor C 12 chargings by resistance R 16, when the voltage of capacitor C 12 reaches the conducting voltage VGTH1 of metal-oxide-semiconductor Q13, the Q13 conducting, when the voltage of capacitor C 12 reached the conducting voltage VGTH2 of metal-oxide-semiconductor Q14, Q14 is conducting also.PWM adjusting pin with the standby pwm chip during metal-oxide-semiconductor Q13 conducting drags down, the then pulse output pin OUT of this chip end no pulse output, thus auxiliary power supply end VCC ' stops to this chip power supply.During metal-oxide-semiconductor Q14 conducting, the electric charge on the power supply VCC end storage capacitor C3 quickens discharge time by two approach discharges of operating current of resistance R 17 and pwm chip, shortens discharge time.When being discharged into capacitor C 3 voltages and being lower than the shutoff threshold voltage of pwm chip, MOSFET is open-minded for the starting of the high pressure of chip internal.Because the existence of resistance R 17 when metal-oxide-semiconductor Q14 conducting, makes VCC voltage not reach the operating voltage that opens of pwm chip, thereby the high voltage startup MOSFET of pwm chip inside pipe is in conducting state always.Like this, the electric charge among the AC power filter capacitor CX1 just can pass through the MOSFET pipe repid discharge of diode D14 or D15 and resistance R 4, pwm chip inside, till the CX1 capacitance charge exhausts.

As Fig. 4, be another embodiment circuit theory diagrams of the utility model, among this embodiment the pwm chip model be FSQ510. relate to AC dump fast the operation principle of response and ac filter capacitor discharging circuit part do not repeat them here with embodiment illustrated in fig. 3 identical.

When the utility model is specifically implemented, N2 end can be directly with exchanges that input N end links to each other or imports N and hold continuous with exchanging by the one or more film inductors altogether in the electromagnetic interface filter or one or more poor film inductor.L2 end can be directly with exchanges that input L end links to each other or imports L and hold continuous with exchanging by the one or more film inductors altogether in the electromagnetic interface filter or one or more poor film inductor.AC signal AC end can be directly with exchanges that input N end links to each other or imports N and hold continuous with exchanging by the one or more film inductors altogether in the electromagnetic interface filter or one or more poor film inductor; Perhaps AC signal AC directly with exchange that input L end links to each other or by the one or more film inductors altogether in the electromagnetic interface filter or one or more poor film inductor with to exchange input L end continuous.

Claims

1. an AC dump responds and the ac filter capacitor discharging circuit fast, connect with current rectifying and wave filtering circuit, inverter circuit, it is characterized in that: comprise connecting the metal-oxide-semiconductor Q14 that is used for storage capacitor C3 discharge, the metal-oxide-semiconductor Q13 that connects with pwm chip PWM adjusting pin and the resistance R 4 that connects with pwm chip high voltage startup pin respectively with pwm chip supply pin in the inverter circuit, resistance R 4 other ends are connected to ac power input end L2, N2 by diode respectively; Described ac supply signal AC connects metal-oxide-semiconductor Q14, Q13 grid by signal transformation circuit and control circuit successively to be realized the control of metal-oxide-semiconductor Q14, Q13 and then realizes control to pwm chip.

2. AC dump according to claim 1 is response and ac filter capacitor discharging circuit fast, it is characterized in that: described shaping circuit comprises triode Q11, and resistance and the diode of described triode Q11 base stage by series connection connects that AC signal end AC, collector electrode connect the pwm chip supply pin, emitter-base bandgap grading connects control circuit by capacitance C11 simultaneously by grounding through resistance.

3. AC dump according to claim 1 is response and ac filter capacitor discharging circuit fast, it is characterized in that: described control circuit comprises triode Q12 and is connected in capacitor C 12 between Q12 collector electrode and the ground; Triode Q12 collector electrode also connects metal-oxide-semiconductor Q14, Q13 grid, also connects the pwm chip supply pin by resistance in addition; Triode Q12 base stage connects capacitance C11 one end, emitter grounding by resistance.

4. respond fast and the ac filter capacitor discharging circuit according to claim 2 or 3 described AC dump, it is characterized in that: the interface of described capacitance C11 and control circuit has also passed through the diode D13 ground connection of discharge process.

5. respond fast and the ac filter capacitor discharging circuit according to claim 2 or 3 described AC dump, it is characterized in that: described metal-oxide-semiconductor Q14 drain electrode connects the supply pin of pwm chip by resistance.

6. respond fast and the ac filter capacitor discharging circuit according to claim 2 or 3 described AC dump, it is characterized in that: triode Q11 base stage is passed through grounding through resistance in the described shaping circuit.