CN101312609B - Flash control circuit - Google Patents
Flash control circuit Download PDFInfo
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- CN101312609B CN101312609B CN2007102007062A CN200710200706A CN101312609B CN 101312609 B CN101312609 B CN 101312609B CN 2007102007062 A CN2007102007062 A CN 2007102007062A CN 200710200706 A CN200710200706 A CN 200710200706A CN 101312609 B CN101312609 B CN 101312609B
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Abstract
The invention relates to a flashlight control circuit, comprising a charging module comprising an oscillator, a flashlight module and a control module for controlling the charging module to start/stop charging the flashlight module, wherein the charging module comprises a protection unit. When the protection unit detects the peak current of the oscillator is higher than a current preset value, the protection unit adopts the control module to control the oscillator to enter in the next charging period. The flashlight control circuit adopts the protection unit to detect the peak current of the oscillator, and when the peak current is over the maximum allowance current of the oscillator, the protection unit adopts the control module to enter the oscillator into the next charging period, thereby effectively protecting the oscillator.
Description
Technical field
The present invention relates to a kind of flash control circuit.
Background technology
See also Fig. 1, general flash control circuit 100 comprises charging module 102, flash modules 104 and control module 106, the charging capacitor of 102 pairs of flash modules 104 of these control module 106 may command charging modules (figure does not show) action of charging.When charging signals becomes high level by low level; Control module 106 makes charging module 102 begin the electric capacity in the flash modules 104 is charged; When the voltage at electric capacity two ends reaches preset value; Then charging signals becomes low level by high level, and control module 106 makes charging module stop the electric capacity in the flash modules 104 is charged.Flash control circuit 100 is through 200 power supplies of the system power supply module in the device at flash control circuit 100 places.
In the prior art, charging module 102 comprises oscillator and has primary coil and the transformer of secondary coil that flash modules 104 comprises rectifier diode.The process that charging capacitor is charged is that the secondary coil of transformer induces induced electromotive force and induced current and the rectifier diode through flash modules 104 charges to charging capacitor.Because the equivalent electric circuit of the primary coil of transformer is the antiresonant circuit of resistance, inductance and electric capacity.In charging process; Because the existence of resistance is arranged in the loop, when electric current was flowed through the coil groups of transformer, coil groups can be generated heat; Electric current is big more; Caloric value is big more, and this moment, the inductance value of primary coil can diminish because temperature raises, and the inductance value of the peak current of transformer and transformer is the relation of being inversely proportional to.Therefore, the peak electricity of the primary coil increase that fails to be convened for lack of a quorum of flowing through.In the electric current rising cycle of the oscillator in charging module 102, when peak current surpassed the maximum current that oscillator connect with this primary coil can bear, oscillator was burnt easily, thus the initiation safety problem.
Summary of the invention
In view of this, be necessary to provide a kind of flash control circuit of protecting oscillator.
A kind of flash control circuit, it comprises: charging module, control module and flash modules.This charging module comprises oscillator.This control module is used to control this charging module flash modules is begun/stop the charging action; Wherein, This charging module comprises protected location; The peak current that monitors the oscillator of flowing through when protected location is during greater than the electric current preset value, and this protected location gets into next charge cycle through this oscillator of control module control.
A kind of flash control circuit, it comprises charging module, flash modules and control module, this charging module comprises oscillator, wherein, this charging module comprises protected location.The oscillator of this control module output oscillation control signal to this charging module, this charging module begins/stops the charging action according to this oscillator signal to flash modules.The peak current that monitors the oscillator of flowing through when protected location is during greater than the electric current preset value, and this protected location output feedback signal is to this control module, and control module gets into next charge cycle according to this this oscillator of feedback signal control.
Described flash control circuit; Through the peak current of protected location monitoring flow through oscillator; When peak current surpassed the maximum current that oscillator can bear, protected location made oscillator get into next charge cycle through control module, thereby effectively protects oscillator.
Description of drawings
Fig. 1 is the functional block diagram of a kind of flash control circuit of the prior art.
The functional block diagram of a kind of flash control circuit that Fig. 2 provides for the embodiment of the invention.
Fig. 3 is a circuit diagram of the flash control circuit among Fig. 2.
Fig. 4 is a sequential chart of the circuit diagram among Fig. 3.
Embodiment
To combine accompanying drawing that the embodiment of the invention is done further to specify below.
See also Fig. 2, first embodiment of the invention provides a kind of flash control circuit 300, and this flash control circuit 300 comprises charging module 302, flash modules 304 and control module 306.This flash control circuit 300 is in the device through flash control circuit 300 places, like magazine system power supply module 200 power supplies of number.This system power supply module 200 comprises system power supply VB.
See also Fig. 3, this charging module 302 comprises oscillator Q1, step-up transformer T1, protected location 308, resistance R 4 and capacitor C 2.This step-up transformer T1 has first polar curve circle and secondary coil.The end of system power supply VB is connected to an end of resistance R 4 and the first polar curve circle of step-up transformer T1 simultaneously, and control module 306 is held with being connected to and be connected to simultaneously to the other end of resistance R 4 through capacitor C 2.This oscillator Q1 is a MOS type FET (Metal-Oxide-SemiconductorField-Effect-Transistor); The drain electrode of this MOS type FET Q1 links to each other with system power supply VB through the primary coil of step-up transformer T1, and grid and the source electrode of this MOS type FET Q1 all are connected to protected location.The secondary coil of step-up transformer T1 is to be connected to flash modules 304.
This protected location 308 comprises that one is set resistance R 1, a comparator A1, a logical AND gate D1, a derailing switch 310 and a DC power supply V.
This end of setting resistance R 1 links to each other with source electrode and input of this comparator A1 of MOS type FET Q1 simultaneously, and the other end of this setting resistance R 1 is held with being connected to.Another input of this comparator A1 links to each other with the positive pole of DC power supply V; The output of this comparator A1 is connected to the input of this logical AND gate D1; The negative pole of DC power supply V is held with being connected to; The input of derailing switch 310 links to each other with the grid of MOS type FET Q1, and the output of this derailing switch 310 links to each other with another input of this logical AND gate D1, and the output of this logical AND gate D1 is connected to an input of this control module 306.When MOS type FET Q1 closed, these derailing switch 310 output low levels were to the input of logical AND gate D1, so logical AND gate D1 output low level is closed protected location 308; When MOS type FET Q1 conducting; These derailing switch 310 output high level are to the input of logical AND gate D1; At this moment, if the output low level of comparator A1 is to another input of logical AND gate D1, then logical AND gate D1 output low level is closed protected location 308; If the output high level of comparator A1 is to another input of logical AND gate D1, then logical AND gate D1 output high level is opened protected location 308.
This flash modules 304 comprises rectifier diode D1, Zener diode D2, charging capacitor C0, capacitor C 1, protective resistance R3 and resistance R 2.The positive pole of rectifier diode D1 links to each other with the secondary coil of step-up transformer T1 and holds through resistance R 2 with being connected to; The negative pole of rectifier diode D1 is connected to the negative pole of Zener diode D2 and the end of charging capacitor C0 simultaneously; The positive pole of Zener diode D2 is connected to an end of capacitor C 1, an end and the control module 306 of protective resistance R3 simultaneously; The other end of charging capacitor C0 is connected to the other end of capacitor C 1 and the other end of protective resistance R3 simultaneously, and holds through resistance R 2 with being connected to.
The input of this control module 306 can be connected to digital signal processor (figure do not show), is used to receive charging signals and controls 302 pairs of flash modules of charging module 304 and carry out/stop the charging action.When the oscillation control signal of control module 306 outputs is low level, MOS type FET Q1 is closed; When the oscillation control signal of control module 306 outputs is high level, make MOS type FET Q1 conducting.
Please consult Fig. 3 and Fig. 4 simultaneously, below the operating state of explanation flash control circuit 300 of the present invention is divided into normal condition and guard mode.
Normal condition:
When charging signals becomes high level by low level; The oscillation control signal of these control module 306 output high level; MOS type FET Q1 conducting this moment; Electric current I 1 flows to the ground end by the system power supply VB of system power supply module 200 through transformer T1 primary coil, MOS type FET Q1 and setting resistance R 1, and the primary coil of step-up transformer T1 begins the storage power that magnetizes, and accomplishes to change magnetic energy into by electric energy.The derailing switch 310 output high level of protected location 308 are to logical AND gate D1.System power supply VB charges through 4 pairs of capacitor C 2 of resistance R.
When the pressure drop of capacitor C 2 during greater than reference voltage, the oscillation control signal of control module 306 output low levels is closed MOS type FET Q1.This reference voltage can be set by the reference power source in the control module 306.At this moment, the secondary coil of step-up transformer T1 induces induced electromotive force and induced current and through rectifier diode D1 the charging capacitor C0 of flash modules 304 is charged.Along with charging is carried out; The secondary coil induced electromotive force of step-up transformer T1 can slowly reduce; When induced electromotive force during, the oscillation control signal of control module 306 output high level less than preset electromotive force, make MOS type FET Q1 once more conducting get into next charge cycle.Cycle charging so repeatedly, when charging capacitor C0 end was charged to the voltage preset value, Zener diode D2 was breakdown, and the A point becomes high level.The high level that control module 306 is ordered according to this A is controlled this charging module 302 and is stopped the charging action.Should determine by DC power supply (figure does not show) institute that loads on the step-up transformer T1 secondary coil that the voltage preset value that this charging capacitor C0 holds was generally 300 volts by preset electromotive force.
In cycle charging process repeatedly, the temperature of transformer T1 primary coil can rise gradually, and the inductance of transformer T1 primary coil is along with decline, and electric current I 1 descends along with the inductance of transformer T1 primary coil and raises.When just beginning; The peak current Ipk of electric current I 1 does not also surpass the maximum current that MOS type FET Q1 can bear; Peak voltage drop Vpk on the setting resistance R 1 of protected location 308 is less than the pressure drop of the DC power supply V of protected location 308; Comparator A1 output low level is to logical AND gate D1, and is as shown in Figure 4.Another input of logical AND gate D1 is by derailing switch 310 input high levels (MOS type FET Q1 is in conducting state), and therefore, the output of logical AND gate D1 is a low level.At this moment, protected location is in closed condition.
Guard mode:
Carrying out along with charging cycle; When the peak current Ipk of electric current I 1 surpasses the maximum current that MOS type FET Q1 can bear; Protected location 308 detects the peak voltage drop Vpk that sets on the resistance R 1 pressure drop greater than the DC power supply V of protected location 308; Comparator A1 output high level is to the input of logical AND gate D1, and is as shown in Figure 4.Because another input of logical AND gate D1 is by derailing switch 310 input high levels (MOS type FET Q1 is in conducting state); Therefore; This logical AND gate D1 is output as high level, protected location 308 is opened, and control module 306 is according to the high level of logical AND gate D1; The oscillation control signal of output low level is closed MOS type FET Q1 and is got into next charge cycle.In the present embodiment, the pressure drop of the DC power supply V of protected location 308 is 48 millivolts.
This protected location 308 is through the peak current Ipk of monitor current I1; When peak current Ipk surpasses the maximum current that MOS type FET Q1 can bear; Protected location 308 is closed MOS type FET Q1 and is got into next charge cycle, thereby effectively protects MOS type FET Q1.
In the actual job process, can set the size of protected location 308 monitoring peak current Ipk through the saturation current of transformer coil.The saturation current of coil is: when the electric current of coil was increasing, the inductance of coil can reduce.Drop to 10% when electric current makes the inductance value of the ferrite core of transformer, the inductance value that is used for the dustcore of storage power drops to 20%.The electric current of coil is called the saturation current of coil at this moment.
The general extra-thin transformer of industry, its saturation current between normal temperature to 60 degree centigrade is about 1.8 peaces ~ 1.6 peaces.The operating current of the primary coil of step-up transformer T1 is less than the saturation current of coil.Therefore, preferably, the monitoring peak current Ipk that protected location 308 is set closes MOS type FET Q1 greater than V/R1=1.6 ampere-hour (V is the DC power supply voltage of protected location).
It is understandable that above-mentioned control module 306 comprises trigger, like set-reset flip-floop, latch, function elements such as gate and comparator, this control module 306 can be with reference to the module of flash control circuit tool controlled function of the prior art and is designed
The related data of present embodiment are for principle of the present invention and enforcement are described better, and those skilled in the art can spirit according to the present invention make other respective change.Certainly, these are according to the variation that the present invention spirit is done, all should be included in the present invention's scope required for protection in.
Claims (7)
1. flash control circuit, it comprises:
Charging module, this charging module comprise oscillator and have the step-up transformer of primary coil, and this oscillator is a MOS type FET, and this MOS type FET is positioned at the outprimary of this step-up transformer;
Flash modules; And
Control module; Be used to control this charging module flash modules is begun/stop the charging action, the grid of this MOS type FET is connected to this control module, it is characterized in that; This charging module comprises protected location; Said protected location comprises that one is set resistance, a comparator, a logical AND gate, a derailing switch and a DC power supply, and this setting resistance one end links to each other with source electrode and input of this comparator of MOS type FET simultaneously, and the other end is held with being connected to; Another input of this comparator links to each other with the positive pole of this DC power supply; The output of this comparator is connected to an input of this logical AND gate, and the negative pole of this DC power supply is held with being connected to, and the input of this derailing switch links to each other with the grid of this MOS type FET; The output of this derailing switch links to each other with another input of this logical AND gate; The output of this logical AND gate is connected to this control module, and the peak current that monitors the oscillator of flowing through when protected location is during greater than the electric current preset value, and this protected location gets into next charge cycle through this oscillator of control module control.
2. flash control circuit as claimed in claim 1 is characterized in that described flash modules comprises charging capacitor and rectifier diode, and this charging module charges to this charging capacitor through rectifier diode.
3. flash control circuit as claimed in claim 1 is characterized in that, described peak current is linear with setting resistance.
4. flash control circuit, it comprises charging module, flash modules and control module; This charging module comprises oscillator and has the step-up transformer of primary coil, and this oscillator is a MOS type FET, and this MOS type FET is positioned at the outprimary of this step-up transformer; The grid of this MOS type FET is connected to control module; It is characterized in that this charging module comprises protected location, this protected location comprises that one is set resistance, a comparator, a logical AND gate, a derailing switch and a DC power supply; This is set resistance one end and links to each other with source electrode and input of this comparator of this MOS type FET simultaneously; The other end is held with being connected to, and another input of this comparator links to each other with the positive pole of this DC power supply, and the output of this comparator is connected to an input of this logical AND gate; The negative pole of this DC power supply is held with being connected to; The input of this derailing switch links to each other with the grid of MOS type FET, and the output of this derailing switch links to each other with another input of this logical AND gate, and the output of this logical AND gate is connected to this control module; The oscillator of this control module output oscillation control signal to this charging module, this charging module begins/stops the charging action according to this oscillation control signal to flash modules; The peak current that monitors the oscillator of flowing through when protected location is during greater than the electric current preset value, and this protected location output feedback signal is to this control module, and control module gets into next charge cycle according to this this oscillator of feedback signal control.
5. flash control circuit as claimed in claim 4, when described oscillation control signal was low level, oscillator cut out, and made charging module begin the charging action to flash modules.
6. flash control circuit as claimed in claim 4, when described oscillation control signal was high level, the oscillator conducting made charging module stop the charging action to flash modules.
7. flash control circuit as claimed in claim 4, described feedback signal exports control module to by logical AND gate, when feedback signal is high level, the oscillation control signal of this control module output low level.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2007102007062A CN101312609B (en) | 2007-05-25 | 2007-05-25 | Flash control circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2007102007062A CN101312609B (en) | 2007-05-25 | 2007-05-25 | Flash control circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101312609A CN101312609A (en) | 2008-11-26 |
| CN101312609B true CN101312609B (en) | 2012-03-14 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2007102007062A Expired - Fee Related CN101312609B (en) | 2007-05-25 | 2007-05-25 | Flash control circuit |
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| Country | Link |
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| CN (1) | CN101312609B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104301475B (en) * | 2013-07-17 | 2018-01-05 | 联芯科技有限公司 | Mobile terminal with flash lamp and flashlight function |
| GB2547568B (en) * | 2014-11-28 | 2019-12-11 | Shenzhen City Pixel Enterprise Ltd | Flashing lamp control circuit |
| CN112332472B (en) * | 2020-10-13 | 2022-05-13 | 维沃移动通信有限公司 | Charging circuit, electronic device and flash lamp control method |
| CN112688381B (en) * | 2020-12-15 | 2023-06-13 | Oppo广东移动通信有限公司 | Charging circuit, circuit control method and electronic equipment |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1815845A (en) * | 2005-02-01 | 2006-08-09 | 乐金电子(中国)研究开发中心有限公司 | Battery charging current self-compensating gear of mobile communication terminal and compensating method thereof |
-
2007
- 2007-05-25 CN CN2007102007062A patent/CN101312609B/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1815845A (en) * | 2005-02-01 | 2006-08-09 | 乐金电子(中国)研究开发中心有限公司 | Battery charging current self-compensating gear of mobile communication terminal and compensating method thereof |
Non-Patent Citations (1)
| Title |
|---|
| JP特开2000-299194A 2000.10.24 |
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| CN101312609A (en) | 2008-11-26 |
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