CN104577966A - Overvoltage protection circuit - Google Patents
Overvoltage protection circuit Download PDFInfo
- Publication number
- CN104577966A CN104577966A CN201510041788.5A CN201510041788A CN104577966A CN 104577966 A CN104577966 A CN 104577966A CN 201510041788 A CN201510041788 A CN 201510041788A CN 104577966 A CN104577966 A CN 104577966A
- Authority
- CN
- China
- Prior art keywords
- resistance
- diode
- chip
- triode
- reference source
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Abstract
The invention discloses an overvoltage protection circuit. The overvoltage protection circuit comprises a sampling circuit, a control driving circuit, a PWM control chip U2 and a feedback optocoupler U3. The sampling circuit comprises a resistor R1, a resistor R2, a resistor R3, a capacitor C1 and a reference source chip U1. The control driving circuit comprises a resistor R4, a resistor R5, an audion Q1, an audion Q2, a diode D1 and a diode D2. The sampling circuit adopts the interior voltage of the reference source chip U1 as reference comparison voltage and therefore is high in accuracy, good in stability and affected very little by the environmental temperature. The capacitor C1 plays a role in anti-interference filtering and can eliminate the influence on the sampling circuit by interference signals. The diode D1 is used for instantly turning off the control output of the feedback input end of the PWM control chip U2. The diode D2 is used for instantly reducing and discharging charges stored by a capacitor C3 of the starting end of the PWM control chip U2, thus when the overvoltage protection circuit works normally after overvoltage protection, only when the capacitor C3 must be filled with charges again, can the starting end of the PWM control chip U2 start working, and the whole circuit plays a role in slow starting.
Description
Technical field
The present invention relates to a kind of protective circuit, specifically a kind of overvoltage crowbar.
Background technology
Overvoltage protection mode in existing Switching Power Supply generally has two kinds; one is adopt voltage stabilizing didoe in series with a resistor; another kind of mode is exactly directly adopt tandem type resistance as the means of overvoltage protection; these two kinds of protected modes are all very coarse; when particularly working near protection working point; overvoltage protection is unstable, causes the damage of Switching Power Supply.
Summary of the invention
The object of the present invention is to provide a kind of protection range wide and adopt the overvoltage crowbar that slow turn-on mode starts, to solve the problem proposed in above-mentioned background technology.
For achieving the above object, the invention provides following technical scheme:
A kind of overvoltage crowbar, comprise sample circuit, control drive circuit, pwm chip U2 and feedback light lotus root U3, sample circuit comprises resistance R1, resistance R2, resistance R3 and a reference source chip U1, and sample circuit adopts a reference source chip U1 builtin voltage as reference comparative voltage, control drive circuit and comprise resistance R4, resistance R5, triode Q1, triode Q2 and diode D1, described resistance R1 and resistance R2 is connected between DC positive source and DC power cathode, the control pole contact resistance R1 and resistance R2 simultaneously of a reference source chip U1, the A pole of a reference source chip U1, resistance R5 is connected DC power cathode and ground connection with triode Q2 emitter simultaneously, K pole connecting triode Q1 base stage and the resistance R3 simultaneously of a reference source chip U1, the other end of resistance R3 connects power supply VCC, power supply VCC also with resistance R4, the Vcc end of electric capacity C2 and pwm chip U2 connects, resistance R4 other end connecting triode Q1 emitter, electric capacity C2 other end ground connection, the collector electrode contact resistance R5 other end and the triode Q2 base stage simultaneously of triode Q1, the collector electrode of triode Q2 connects diode D1 negative pole, diode D1 positive pole connects the feedback end of pwm chip U2 and 1 pin of feedback light lotus root U3 simultaneously, the control that diode D1 is used for turning off instantaneously pwm chip U2 feedback input end exports.
As the further scheme of the present invention: described a reference source chip U1 adopts TL431 a reference source chip.
As the further scheme of the present invention: described sample circuit also comprises and is connected in parallel on the electric capacity C1 that anti-interference filtration effect is played at resistance R2 two ends.
As the further scheme of the present invention: described control drive circuit also comprises diode D2, diode D2 positive pole connects pwm chip U2 start end and electric capacity C3, electric capacity C3 other end ground connection, diode D2 negative pole connecting triode Q2 collector electrode; The electric charge that the electric capacity C3 that diode D2 is used for dragging down release pwm chip U2 start end instantaneously stores; when normally working after overvoltage crowbar overvoltage protection; the electric charge of electric capacity C3 must be refilled; pwm chip U2 start end could start work, makes overvoltage crowbar play the effect of slow turn-on.
Compared with prior art, the invention has the beneficial effects as follows:
(1) sample circuit adopts a reference source chip U1 builtin voltage as reference comparative voltage, and its precision is high, good stability, influenced by ambient temperature little; In addition, compared with prior art, the electric capacity C1 of increase plays anti-interference filtration effect, can eliminate the impact of interference signal on sample circuit.
(2) control drive circuit and have employed feedback input end and the start end that diode D1 and diode D2 drags down pwm chip U2 respectively, protect simultaneously; Compared with prior art, after adding diode D2, make complete machine when the work of protection, work that can be reliable and stable.The control that diode D1 is used for turning off instantaneously pwm chip U2 feedback input end exports; The electric charge that the electric capacity C3 that diode D2 is used for dragging down release pwm chip U2 start end instantaneously stores, when normally working after making circuit protection, must be again full of by the electric charge of electric capacity C3, pwm chip U2 start end could start work, makes whole circuit play the effect of slow turn-on; Therefore, when input dc power is pressed in work near protection point, overvoltage protection effect can all be played, and reliable and stablizing effect is good.
Accompanying drawing explanation
Fig. 1 is the circuit diagram of overvoltage crowbar.
Embodiment
Be described in more detail below in conjunction with the technical scheme of embodiment to this patent.
Refer to Fig. 1, in the embodiment of the present invention, a kind of overvoltage crowbar, comprise sample circuit, control drive circuit, pwm chip U2 and feedback light lotus root U3, sample circuit comprises resistance R1, resistance R2, resistance R3 and a reference source chip U1, and sample circuit adopts a reference source chip U1 builtin voltage as reference comparative voltage, and its precision is high, good stability, influenced by ambient temperature little, described a reference source chip U1 adopts TL431 a reference source chip, control drive circuit and comprise resistance R4, resistance R5, triode Q1, triode Q2 and diode D1, described resistance R1 and resistance R2 is connected between DC positive source and DC power cathode, the control pole contact resistance R1 and resistance R2 simultaneously of a reference source chip U1, the A pole of a reference source chip U1, resistance R5 is connected DC power cathode and ground connection with triode Q2 emitter simultaneously, K pole connecting triode Q1 base stage and the resistance R3 simultaneously of a reference source chip U1, the other end of resistance R3 connects power supply VCC, power supply VCC also with resistance R4, the Vcc end of electric capacity C2 and pwm chip U2 connects, resistance R4 other end connecting triode Q1 emitter, electric capacity C2 other end ground connection, the collector electrode contact resistance R5 other end and the triode Q2 base stage simultaneously of triode Q1, the collector electrode of triode Q2 connects diode D1 negative pole, diode D1 positive pole connects the feedback end of pwm chip U2 and 1 pin of feedback light lotus root U3 simultaneously, the control that diode D1 is used for turning off instantaneously pwm chip U2 feedback input end exports.
In the present invention, described sample circuit also comprises and is connected in parallel on the electric capacity C1 that anti-interference filtration effect is played at resistance R2 two ends, adds electric capacity C1 and can eliminate the impact of interference signal on sample circuit.
In the present invention, described control drive circuit also comprises diode D2, and diode D2 positive pole connects pwm chip U2 start end and electric capacity C3, electric capacity C3 other end ground connection, diode D2 negative pole connecting triode Q2 collector electrode; The electric charge that the electric capacity C3 that diode D2 is used for dragging down release pwm chip U2 start end instantaneously stores; when normally working after overvoltage crowbar overvoltage protection; the electric charge of electric capacity C3 must be refilled; pwm chip U2 start end could start work, makes overvoltage crowbar play the effect of slow turn-on.Therefore when the direct voltage of DC power supply input is when protecting work near point, all can play overvoltage protection effect, and reliably and stablizing effect good.Described control drive circuit have employed feedback input end and the start end that diode D1 and diode D2 drags down pwm chip U2 respectively, protects simultaneously; Compared with prior art, after adding diode D2, make complete machine when the work of protection, work that can be reliable and stable.
Operation principle of the present invention is: the direct voltage of DC power supply input, after resistance R1, resistance R2 and electric capacity C1 dividing potential drop, obtains a fixing sampling voltage, then compares with a reference source chip U1 builtin voltage; When sampling voltage is less than builtin voltage, a reference source chip U1 exports as high level signal; When sampling voltage is greater than builtin voltage, a reference source chip U1 exports as low level signal, triode Q1 conducting, drive triode Q2 conducting, now triode Q2 exports as low level, dragged down feedback input end and the start end of pwm chip U2 by diode D1, diode D2 respectively, thus close output control signal, play overvoltage shutoff effect.
Above the better embodiment of this patent is explained in detail, but this patent is not limited to above-mentioned execution mode, in the ken that one skilled in the relevant art possesses, can also makes a variety of changes under the prerequisite not departing from this patent aim.
Claims (4)
1. an overvoltage crowbar, it is characterized in that, comprise sample circuit, control drive circuit, pwm chip U2 and feedback light lotus root U3, sample circuit comprises resistance R1, resistance R2, resistance R3 and a reference source chip U1, and sample circuit adopts a reference source chip U1 builtin voltage as reference comparative voltage, control drive circuit and comprise resistance R4, resistance R5, triode Q1, triode Q2 and diode D1, described resistance R1 and resistance R2 is connected between DC positive source and DC power cathode, the control pole contact resistance R1 and resistance R2 simultaneously of a reference source chip U1, the A pole of a reference source chip U1, resistance R5 is connected DC power cathode and ground connection with triode Q2 emitter simultaneously, K pole connecting triode Q1 base stage and the resistance R3 simultaneously of a reference source chip U1, the other end of resistance R3 connects power supply VCC, power supply VCC also with resistance R4, the Vcc end of electric capacity C2 and pwm chip U2 connects, resistance R4 other end connecting triode Q1 emitter, electric capacity C2 other end ground connection, the collector electrode contact resistance R5 other end and the triode Q2 base stage simultaneously of triode Q1, the collector electrode of triode Q2 connects diode D1 negative pole, diode D1 positive pole connects the feedback end of pwm chip U2 and 1 pin of feedback light lotus root U3 simultaneously, the control that diode D1 is used for turning off instantaneously pwm chip U2 feedback input end exports.
2. overvoltage crowbar according to claim 1, is characterized in that, described a reference source chip U1 adopts TL431 a reference source chip.
3. overvoltage crowbar according to claim 1, is characterized in that, described sample circuit also comprises and is connected in parallel on the electric capacity C1 that anti-interference filtration effect is played at resistance R2 two ends.
4. according to the overvoltage crowbar one of claim 1-3 Suo Shu, it is characterized in that, described control drive circuit also comprises diode D2, and diode D2 positive pole connects pwm chip U2 start end and electric capacity C3, electric capacity C3 other end ground connection, diode D2 negative pole connecting triode Q2 collector electrode; The electric charge that the electric capacity C3 that diode D2 is used for dragging down release pwm chip U2 start end instantaneously stores; when normally working after overvoltage crowbar overvoltage protection; the electric charge of electric capacity C3 must be refilled; pwm chip U2 start end could start work, makes overvoltage crowbar play the effect of slow turn-on.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510041788.5A CN104577966A (en) | 2015-01-28 | 2015-01-28 | Overvoltage protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510041788.5A CN104577966A (en) | 2015-01-28 | 2015-01-28 | Overvoltage protection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN104577966A true CN104577966A (en) | 2015-04-29 |
Family
ID=53093443
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201510041788.5A Pending CN104577966A (en) | 2015-01-28 | 2015-01-28 | Overvoltage protection circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN104577966A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017219281A1 (en) * | 2016-06-22 | 2017-12-28 | 张升泽 | Method and system for current alarm for electronic chip |
| WO2017219280A1 (en) * | 2016-06-22 | 2017-12-28 | 张升泽 | Method and system for voltage alarm for electronic chip |
| CN108718074A (en) * | 2018-07-06 | 2018-10-30 | 青岛海信电器股份有限公司 | A kind of overvoltage crowbar and terminal installation |
-
2015
- 2015-01-28 CN CN201510041788.5A patent/CN104577966A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017219281A1 (en) * | 2016-06-22 | 2017-12-28 | 张升泽 | Method and system for current alarm for electronic chip |
| WO2017219280A1 (en) * | 2016-06-22 | 2017-12-28 | 张升泽 | Method and system for voltage alarm for electronic chip |
| CN108718074A (en) * | 2018-07-06 | 2018-10-30 | 青岛海信电器股份有限公司 | A kind of overvoltage crowbar and terminal installation |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN104577993B (en) | Switching Power Supply input voltage protection circuit | |
| CN103606895B (en) | A kind of overvoltage turn-off protection circuit | |
| CN201663720U (en) | Induction cooker controller with IGBT protective circuit and induction cooler | |
| CN204258271U (en) | A kind of under-voltage protective switch of the short circuit supply unit | |
| CN201629569U (en) | Over-voltage protection circuit of USB interface | |
| CN104362608A (en) | Overvoltage suppression and under-voltage surge detection circuit | |
| CN104577966A (en) | Overvoltage protection circuit | |
| CN205319797U (en) | Industrial automation produces monitored control system | |
| CN106034369A (en) | LED power supply with short-circuit protection circuit | |
| CN203104871U (en) | Intelligently controlled DALI (digital addressable lighting interface) dimming control device | |
| CN101763134B (en) | Parallel voltage stabilizing circuit | |
| CN201937235U (en) | Overcurrent protection circuit | |
| CN103944381A (en) | Voltage output circuit based on PWM control | |
| CN104852563A (en) | Switching power supply external soft start circuit | |
| CN205247256U (en) | Ripples current -limiting circuit one by one along with busbar voltage change | |
| CN202978235U (en) | >Switch power supply high-precision overvoltage protection circuit | |
| CN204333903U (en) | A kind of overvoltage crowbar | |
| CN204180331U (en) | A kind of protective circuit of LED power | |
| CN204349418U (en) | A kind of overvoltage crowbar | |
| CN102709870A (en) | Power supply protection circuit and electronic product | |
| CN102969704A (en) | Pre-charging circuit | |
| CN214412270U (en) | Frequency converter output overcurrent protection circuit | |
| CN204538786U (en) | A kind of overvoltage charge protection charger | |
| CN205490464U (en) | Delay circuit of repid discharge | |
| CN112542818B (en) | Input undervoltage protection circuit and power panel comprising same |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| WD01 | Invention patent application deemed withdrawn after publication | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20150429 |