CN102332901A - Switching circuit and display device - Google Patents
Switching circuit and display device Download PDFInfo
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- CN102332901A CN102332901A CN201110232087A CN201110232087A CN102332901A CN 102332901 A CN102332901 A CN 102332901A CN 201110232087 A CN201110232087 A CN 201110232087A CN 201110232087 A CN201110232087 A CN 201110232087A CN 102332901 A CN102332901 A CN 102332901A
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Abstract
The invention relates to a switching circuit and a display device. The switching circuit and the display device comprise a P metal semi-transistor, a first resistor and a first capacitor; the source electrode of the P metal semi-transistor is coupled with a first power supply; the first end of the first resistor is coupled with a power supply converting unit, and the second end of the first resistor is coupled with grid electrode of the P metal semi-transistor; and the first end of the first capacitor is coupled with the grid electrode of the P metal semi-transistor, and the second of the first capacitor is coupled with the source electrode of the P metal semi-transistor. In the invention, a switching circuit capable of reducing the influence of the temperature to the opening time of the switch is provided.
Description
[technical field]
The invention relates to a kind of switching circuit and display unit, particularly about a kind of switching circuit that reduces variations in temperature to the opening time influence of switch.
[background technology]
In general electronic installation, often need switchable switch be set, with the opportunity of decision supplying DC power source to DC power supply.Yet; At switch by the moment that is closed to unlatching; Current strength can moment quick-fried increasing and produce the electric current (Inrush current) of surging; Such phenomenon is easy to cause the damage of inside circuit element, and therefore also some switching circuit can go design with suppressed mechanism to the electric current of surging, with load of back level and the switch (being generally a control switch transistor) in the protection switch circuit.
See also Fig. 1, it is a kind of sketch map with switching circuit 100 of the electric current mechanism that prevents to surge.Switching circuit 100 includes a npn type bipolar junction transistor (Bipolar Junction Transistor-BJT) Q1, resistance R 1, R2, RC, capacitor C 1, Cout, and P type MOS transistor M1.Npn type bipolar junction transistor Q1 receives an input signal source Input through resistance R 1, to open or to close according to input signal source Input.When npn type bipolar junction transistor Q1 is unlocked; Originally the collection electrode potential of the npn type bipolar junction transistor Q1 that is drawn high through resistance R C by the electric power of power supply PWR1 can be dragged down; And and then open the current potential of P type MOS transistor (MOSFET) M1; Make the electric power of power supply PWR2 of the source electrode be positioned at P type MOS transistor M1 be able to transfer to node Output, and accomplish the program of power-on PWR2 through P type MOS transistor M1.
The opening time of npn type bipolar junction transistor Q1 mainly is to control by the resistance value of resistance R 1, R2 and the capacitance of capacitor C 1, and the opening time of P type MOS transistor M1 then is to come indirect controlling through the emitter potential of the opening time of npn type bipolar junction transistor Q1 and npn type bipolar junction transistor Q1; By the opening time of P type MOS transistor M1 being controlled indirectly through npn type bipolar junction transistor Q1, the generation of the electric current that can effectively prevent to surge.Yet; When operating under the different temperatures that switching circuit 100 is differing greatly; The switching required time of collection electrode potential between high potential and electronegative potential of npn type bipolar junction transistor Q1 can produce bigger variation and instability, and and then makes that indirectly the opening time of P type MOS transistor M1 is also and then unstable.Such wild effect very easily makes the unlatching sequential of power-on circuit 100 mistake occur, and has influence on the whole sequential of the system of applied power source open circuit 100, and produces the running mistake that can't expect.
See also Fig. 2, it is the current potential and the time relationship generalized schematic of part of nodes shown in Figure 1.Main diagram has potential curve, the node Output of input signal source Input to be positioned at potential curve output25 ℃ of 25 degree Celsius, node Output to be positioned at potential curve output65 ℃ of 65 degree Celsius, node Output and to be positioned at curve such as potential curve output-10 ℃ of-10 degree Celsius among Fig. 2.Observing Fig. 2 can know; When input signal Input by electronegative potential when high potential needs about 10 milliseconds time; In operating temperature is that-10 degree Celsius are interval to the temperature difference of 65 degree Celsius, represent output node Output correspondence required time of switching electric potential of output voltage to be about 46 milliseconds and does not wait to 64 milliseconds; Observing error line ER1 shown in Figure 2 or ER2 can know, the electric power starting time difference that the above-mentioned temperature difference causes can reach 20 milliseconds nearly, and this comes the switching circuit 100 of power-on for the accurate sequential of needs, is the insufferable time difference.
[summary of the invention]
The object of the present invention is to provide a kind of switching circuit, it comprises: P type MOS transistor, and its source electrode is coupled to first power supply; First resistance, its first end is coupled to power conversion unit, and second end of this first resistance is coupled to the grid of this P type MOS transistor; And first electric capacity, its first end is coupled to the grid of this P type MOS transistor, and second end of this first electric capacity is coupled to the source electrode of this P type MOS transistor.
As optional technical scheme, this power conversion unit is used for converting an input signal source into second source; Wherein when the current potential in this input signal source was higher than a critical voltage, the current potential of this second source was the position of rationing the power supply, and when the current potential in this input signal source was lower than this critical voltage, the current potential of this second source was a upper limit current potential.
As further optional technical scheme, this power conversion unit comprises: npn type bipolar junction transistor, its base stage are coupled to this input signal source, and the collection utmost point of this npn type bipolar junction transistor is coupled to this first end and the 3rd power supply of this first resistance.
As further optional technical scheme, the emitter grounding of this npn type bipolar junction transistor.
As further optional technical scheme, this power conversion unit comprises in addition: second resistance, its first end is coupled to this input signal source, and second end of this second resistance is coupled to the base stage of this npn type bipolar junction transistor.
As further optional technical scheme, this power conversion unit comprises in addition: second resistance, its first end is coupled to the collection utmost point of this npn type bipolar junction transistor, and second end of this second resistance is coupled to the 3rd power supply.
As optional technical scheme, described switching circuit is characterized in that comprising: second electric capacity, its first end is coupled to the drain electrode of this P type MOS transistor.
As further optional technical scheme, the second end ground connection of this second electric capacity.
As optional technical scheme; The resistance value of this first resistance is controllable resistance value; The capacitance of this first electric capacity is controllable capacitance, and the opening time of this P type MOS transistor is adjusted by this resistance value of this first resistance of control and this capacitance of this first electric capacity.
The present invention also aims to provide a kind of display unit, it comprises: display floater and above-mentioned switching circuit; Switching circuit provides electric power to said display floater.
Compared with prior art, the present invention originally is a kind of switching circuit that reduces temperature to the opening time influence of switch.
[description of drawings]
Fig. 1 is a kind of existing sketch map with switching circuit of the electric current mechanism that prevents to surge.
Fig. 2 is the current potential and the time relationship generalized schematic of part of nodes shown in Figure 1.
Fig. 3 is the sketch map according to one embodiment of the invention institute exposure switching circuit.
Fig. 4 is in one embodiment of the invention, the current potential and the time relationship generalized schematic of part of nodes in the switching circuit shown in Figure 3.
[embodiment]
See also Fig. 3, it is the sketch map according to one embodiment of the invention institute exposure switching circuit 200.Switching circuit 200 comprises P type MOS transistor M1, resistance R T, capacitor C T and Cout and power conversion unit 210.
The source electrode of P type MOS transistor M1 is coupled to power supply PWR2.One first end of resistance R T receives a power supply PWR3 with cause power conversion unit 210, and one second end of resistance R T is coupled to the grid of P type MOS transistor M1.First end of capacitor C T is coupled to the grid of P type MOS transistor M1, and one second end of capacitor C T is coupled to the source electrode of P type MOS transistor M1.
One first end of capacitor C out is coupled to the drain electrode of P type MOS transistor M1, and its second end ground connection.Capacitor C out is used to provide the buffering of node Output when charge and discharge.
With the unlatching of control P type MOS transistor M1 whether power conversion unit 210 is used for converting input signal source Input into power supply PWR3.Power conversion unit 210 comprises npn type bipolar junction transistor Q1, reaches resistance R B and RC.The base stage of npn type bipolar junction transistor Q1 is coupled to input signal source Input through resistance R B.The collection utmost point of npn type bipolar junction transistor Q1 is coupled to this first end of resistance R T, and the collection utmost point of npn type bipolar junction transistor Q1 is coupled to power supply PWR1 through resistance R C.The emitter grounding of npn type bipolar junction transistor Q1.
In power conversion unit 210; When the signal of input signal source Input is that high potential is when (for example being higher than a critical voltage); Npn type bipolar junction transistor Q1 can be unlocked, and the potential drop of the collection utmost point of npn type bipolar junction transistor Q1 is low to moderate ration the power supply the position and opens P type MOS transistor M1; Anti-; When the signal of input signal source Input is electronegative potential (for example being lower than this critical voltage); Npn type bipolar junction transistor Q1 can be closed; And make power supply PWR1 charge to a upper voltage limit to the collection utmost point of npn type bipolar junction transistor Q1 through resistance R C, to close P type MOS transistor M1.For instance, in one embodiment of this invention, the current potential of input signal source Input can be the 0-3.3 volt, and this critical voltage is 1.8 volts, and the current potential of power supply PW3 can be 1.2 volts (lower limit current potentials) to 5 volts (upper limit current potentials); When the current potential of input signal source Input during at the 0-1.8 volt, the current potential of power supply PW3 can be near 5 volts, and when the current potential of input signal source Input during at the 1.8-3.3 volt, the current potential of power supply PW3 can be near 1.2 volts.
The capacitance of the resistance value of resistance R T and capacitor C T is controllable, and switching circuit 200 mainly is to come the directly opening time of control P type MOS transistor M1 by the may command resistance value of resistance R T and the controllable capacitance value of capacitor C T.Compared to coming the open-interval mechanism of control P type MOS transistor M1 indirectly with npn type bipolar junction transistor Q1 shown in Fig. 1; Switching circuit 200 shown in Figure 3 is except the acute variation that can avoid variations in temperature the opening time of P type MOS transistor M1 is caused; Can also reach the effect of the electric current that prevents to surge by direct opening time of restriction P type MOS transistor M1, the function of the electric current that also is about to prevent to surge is passed to P type MOS transistor M1 by npn type bipolar junction transistor Q1.The another one benefit of the above-mentioned practice is; Since the current strength that can bear of npn type two-carrier transistor Q1 compared to P type MOS transistor M1 come little; Make switching circuit 200 can bear bigger current strength and the smooth load device that is coupled to node Output that drives, this load device can be a display floater.
In one embodiment of this invention, the mode adjusted by the capacitance of the resistance value of resistance R T and capacitor C T can be represented as follows the opening time of P type MOS transistor M1:
Wherein t represents the opening time of P type MOS transistor M1, and R represents the resistance value of resistance R T, and C represents the capacitance of capacitor C T, V
InRepresent the potential value of the collection interpolar of resistance R 1 and npn type bipolar junction transistor Q1, and V
OutThe potential value of representation node Output.Therefore observing formula (1) can know, if the resistance value R of direct controlling resistance RT and the capacitance C of capacitor C T, the opening time t of P type MOS transistor M1 can be limited the length of opening time t and prevent the electric current of surging with effective by directly control.In addition; Under the prerequisite that the capacitance C of the resistance value R of resistance R T and capacitor C T is all fixing when different temperatures; The opening time t of P type MOS transistor M1 can not produce violent change yet, makes that therefore switching circuit shown in Figure 3 200 is able under the temperature of violent change, still can keep leveling off to the consistent opening time.
The function mode of switching circuit 200 is described below: when input signal source Input was in electronegative potential, npn type bipolar junction transistor Q1 can be closed and make its collection utmost point to be in high potential (that is power-switching circuit 210 is changed out the power supply PW3 of high potential) through power supply PW1; Thus, P type MOS transistor M1 can be closed and power supply PWR2 can't be passed through, and makes node Output be in electronegative potential.And when input signal source Input transfers high potential to by electronegative potential; Npn type bipolar junction transistor Q1 can be unlocked, and makes the collection utmost point of npn type bipolar junction transistor Q1 be in electronegative potential (that is power-switching circuit 210 is changed out the power supply PW3 of electronegative potential) by discharge; Thus, P type MOS transistor M1 can be unlocked and make power supply PWR2 be able to through, and make node Output by power supply PWR2 charging and be in high potential.Yet; Under the prerequisite that the capacitance of the resistance value of resistance R T and capacitor C T is all fixed when variations in temperature is violent; Node Output the minimum and unlikely variation that influences the electric power starting sequential will only occur by the transformation period that electronegative potential transfers high potential to; And because the capacitance of the resistance value of resistance R T and capacitor C T can be by directly control, the generation of the electric current that therefore also is prone to avoid to surge.
See also Fig. 4, it is in one embodiment of the invention, the current potential and the time relationship generalized schematic of part of nodes in the switching circuit 200 shown in Figure 3.Input signal source Input shown in Figure 4 is identical with input signal source Input shown in Figure 2; Yet owing to can directly adjust by the resistance value of controlling resistance RT and the capacitance of capacitor C T the switching time of P type MOS transistor M1 among Fig. 3; Therefore after input signal source Input transfers high potential to by electronegative potential; The weak point of change-over time that can be more shown in Figure 2 except the change-over time of the current potential of node Output; Node Output corresponding to-10 degree Celsius, 25 degree Celsius, and output-10 ℃ of the different potentials curve, output25 of 65 degree Celsius ℃, output65 ℃ between time difference also significantly shorten than prior art, therefore can provide stable power to open the system of sequential to application switch circuit 200.
Please note; Because above-mentioned power conversion unit 210 significant feature are to provide the power supply of opening P type MOS transistor M1; Therefore power conversion unit shown in Figure 3 210 is replaced to the switching circuit that other device or modules produced that the power supply of opening P type MOS transistor M1 can be provided equally, must be regarded as embodiments of the invention.
Though the present invention discloses as above with embodiment, so it is not that protection scope of the present invention is when being as the criterion with claims in order to qualification the present invention.
Claims (10)
1. switching circuit is characterized in that comprising:
P type MOS transistor, its source electrode is coupled to first power supply;
First resistance, its first end is coupled to power conversion unit, and second end of this first resistance is coupled to the grid of this P type MOS transistor; And
First electric capacity, its first end is coupled to the grid of this P type MOS transistor, and second end of this first electric capacity is coupled to the source electrode of this P type MOS transistor.
2. switching circuit as claimed in claim 1 is characterized in that this power conversion unit is used for converting an input signal source into second source;
Wherein when the current potential in this input signal source was higher than a critical voltage, the current potential of this second source was the position of rationing the power supply, and when the current potential in this input signal source was lower than this critical voltage, the current potential of this second source was a upper limit current potential.
3. switching circuit as claimed in claim 2; It is characterized in that this power conversion unit comprises: npn type bipolar junction transistor; Its base stage is coupled to this input signal source, and the collection utmost point of this npn type bipolar junction transistor is coupled to this first end and the 3rd power supply of this first resistance.
4. switching circuit as claimed in claim 3 is characterized in that the emitter grounding of this npn type bipolar junction transistor.
5. switching circuit as claimed in claim 3 is characterized in that this power conversion unit comprises in addition:
Second resistance, its first end is coupled to this input signal source, and second end of this second resistance is coupled to the base stage of this npn type bipolar junction transistor.
6. switching circuit as claimed in claim 3 is characterized in that this power conversion unit comprises in addition:
Second resistance, its first end is coupled to the collection utmost point of this npn type bipolar junction transistor, and second end of this second resistance is coupled to the 3rd power supply.
7. switching circuit as claimed in claim 1 is characterized in that comprising:
Second electric capacity, its first end is coupled to the drain electrode of this P type MOS transistor.
8. switching circuit as claimed in claim 7 is characterized in that the second end ground connection of this second electric capacity.
9. switching circuit as claimed in claim 1; The resistance value that it is characterized in that this first resistance is controllable resistance value; The capacitance of this first electric capacity is controllable capacitance, and the opening time of this P type MOS transistor is adjusted by this resistance value of this first resistance of control and this capacitance of this first electric capacity.
10. display unit is characterized in that comprising:
Display floater; And
Like any described switching circuit in the claim 1 to 9;
Said switching circuit provides electric power to said display floater.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110232087A CN102332901A (en) | 2011-08-15 | 2011-08-15 | Switching circuit and display device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110232087A CN102332901A (en) | 2011-08-15 | 2011-08-15 | Switching circuit and display device |
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| Publication Number | Publication Date |
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| CN102332901A true CN102332901A (en) | 2012-01-25 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201110232087A Pending CN102332901A (en) | 2011-08-15 | 2011-08-15 | Switching circuit and display device |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104137418B (en) * | 2012-02-29 | 2017-06-16 | 精工半导体有限公司 | On-off circuit |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1674438A (en) * | 2004-03-23 | 2005-09-28 | 华为技术有限公司 | Circuit for positive power source inputting load electrifying slow starting |
| TW200803105A (en) * | 2006-06-02 | 2008-01-01 | Hon Hai Prec Ind Co Ltd | Circuit for restraining surge current and surge voltage |
| CN101236316A (en) * | 2007-02-02 | 2008-08-06 | 群康科技(深圳)有限公司 | LCD device electric supply and discharging circuit |
| CN201708697U (en) * | 2010-05-31 | 2011-01-12 | 比亚迪股份有限公司 | Direct-current power source switching device |
-
2011
- 2011-08-15 CN CN201110232087A patent/CN102332901A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1674438A (en) * | 2004-03-23 | 2005-09-28 | 华为技术有限公司 | Circuit for positive power source inputting load electrifying slow starting |
| TW200803105A (en) * | 2006-06-02 | 2008-01-01 | Hon Hai Prec Ind Co Ltd | Circuit for restraining surge current and surge voltage |
| CN101236316A (en) * | 2007-02-02 | 2008-08-06 | 群康科技(深圳)有限公司 | LCD device electric supply and discharging circuit |
| CN201708697U (en) * | 2010-05-31 | 2011-01-12 | 比亚迪股份有限公司 | Direct-current power source switching device |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104137418B (en) * | 2012-02-29 | 2017-06-16 | 精工半导体有限公司 | On-off circuit |
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Application publication date: 20120125 |