CN204392078U - A kind of voltage threshold testing circuit - Google Patents
A kind of voltage threshold testing circuit Download PDFInfo
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- CN204392078U CN204392078U CN201420860602.XU CN201420860602U CN204392078U CN 204392078 U CN204392078 U CN 204392078U CN 201420860602 U CN201420860602 U CN 201420860602U CN 204392078 U CN204392078 U CN 204392078U
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Abstract
The utility model provides a kind of voltage threshold testing circuit, comprise conducting voltage testing circuit, shutoff voltage testing circuit and signal output apparatus, shutoff voltage testing circuit is connected across between conducting voltage testing circuit and signal output apparatus, conducting voltage testing circuit is for detecting conducting voltage threshold value, shutoff voltage testing circuit is for detecting shutoff voltage threshold value, and signal output apparatus is used for according to testing result equipment output to the back-end control signal.The voltage threshold testing circuit that the utility model provides, comprise conducting voltage testing circuit, shutoff voltage testing circuit, conducting voltage testing circuit is for detecting conducting voltage threshold value, shutoff voltage testing circuit is for detecting shutoff voltage threshold value, correspond respectively to conducting and turn off two control signals, avoid input voltage vin just when the threshold value critical point fluctuation preset, produce continuous print switching signal Sout.
Description
Technical field
The utility model relates to a kind of voltage threshold testing circuit.
Background technology
Common DC/DC Switching Power Supply control chip allows to work under lower input voltage.And when output loading remains unchanged, the reduction of input voltage will cause starting current significantly to increase.In extreme circumstances, even can cause prime power initiation fault or fusing input fuse.In this kind of operational environment, DC/DC switch power module needs to realize starting in appropriate input voltage range.
Fig. 1 provides a kind of input voltage detection circuit schematic diagram of prior art.
As shown in Figure 1, resistance R1 and R3 forms resistor network, realizes the threshold test to input voltage vin.The triode Q1 of rear end and resistance R2, R4, realize threshold test being converted to low and high level and export Sout.
Although circuit shown in Fig. 1 can complete the detection of input voltage, when input voltage vin is just in the threshold value critical point fluctuation preset, the Sout of circuit will produce continuous print switching signal, have a strong impact on the normal work of follow-up DC/DC Switching Power Supply.
Summary of the invention
For the defect existed in prior art, the purpose of this utility model is to provide a kind of voltage threshold testing circuit, this voltage threshold testing circuit, two voltage thresholds are had to correspond respectively to conducting and turn off two control signals, avoid input voltage vin just when the threshold value critical point fluctuation preset, produce continuous print switching signal Sout.
The utility model provides a kind of voltage threshold testing circuit, comprise conducting voltage testing circuit, shutoff voltage testing circuit and signal output apparatus, shutoff voltage testing circuit is connected across between conducting voltage testing circuit and signal output apparatus, conducting voltage testing circuit is for detecting conducting voltage threshold value, shutoff voltage testing circuit is for detecting shutoff voltage threshold value, and signal output apparatus is used for according to testing result equipment output to the back-end control signal.
Further, conducting voltage testing circuit comprises resistance R1, voltage-stabiliser tube DW1 and the resistance R2 of series connection.
Further, signal output apparatus comprises resistance R4 and triode Q2, and the first end of resistance R4 is connected with the positive pole of input voltage, and second end of resistance R4 is connected with the collector electrode of triode Q2, the current collection very testing result output Sout of triode Q2.
In the voltage threshold testing circuit that the present embodiment provides, the resistance 4 in signal output apparatus is pull-up resistor, and pull-up resistor can be connected on input voltage.
Further, signal output apparatus comprises resistance R4 and triode Q2, and the first end of resistance R4 is connected with the positive pole of output voltage, and second end of resistance R4 is connected with the collector electrode of triode Q2, the current collection very testing result output Sout of triode Q2.
In the voltage threshold testing circuit that the present embodiment provides, the resistance 4 in signal output apparatus, also according to the demand of rear end DC/DC Switching Power Supply or miscellaneous equipment, can be connected on suitable voltage source.
Further, the base stage of triode Q2, is connected with the link of voltage-stabiliser tube DW1 and resistance R2.
Further, shutoff voltage testing circuit comprises triode Q1, voltage-stabiliser tube DW2 and the resistance R3 of series connection.
Further, resistance R3 is connected with testing result output Sout.
Further, shutoff voltage threshold value is lower than conducting voltage threshold value.
Further, the difference of shutoff voltage threshold value and conducting voltage threshold value is more than or equal to 0.5V.
Compared with prior art, the voltage threshold testing circuit that the utility model provides has following beneficial effect:
Comprise conducting voltage testing circuit, shutoff voltage testing circuit, conducting voltage testing circuit is for detecting conducting voltage threshold value, shutoff voltage testing circuit is for detecting shutoff voltage threshold value, correspond respectively to conducting and turn off two control signals, avoid input voltage vin just when the threshold value critical point fluctuation preset, produce continuous print switching signal Sout.
Accompanying drawing explanation
Fig. 1 is voltage threshold testing circuit figure in prior art;
Fig. 2 is the schematic diagram of the voltage threshold testing circuit of an embodiment of the present utility model.
Embodiment
For a more detailed description to embodiment of the present utility model below in conjunction with accompanying drawing.
As shown in Figure 2, the voltage threshold testing circuit of an embodiment of the present utility model, comprise conducting voltage testing circuit, shutoff voltage testing circuit and signal output apparatus, shutoff voltage testing circuit is connected across between conducting voltage testing circuit and signal output apparatus.
Conducting voltage testing circuit is for detecting conducting voltage threshold value, comprise the resistance R1 of series connection, voltage-stabiliser tube DW1 and resistance R2, conducting voltage testing circuit is directly parallel to power input, by selecting the voltage-stabiliser tube DW1 of corresponding parameter, obtains the conducting voltage threshold value V1 needed:
V1＝Vth*(R1+R2)/R1+Vz1
Wherein Vth is the pressure drop of the PN junction of voltage-stabiliser tube DW1, Vth=0.7V; Vz 1 is the puncture voltage of voltage-stabiliser tube DW1, and R1 is the resistance of resistance R1, and R2 is the resistance of resistance R2.
Because voltage-stabiliser tube DW1 needs suitable electric current normally to work, when therefore selecting resistance value R1 and R2 in this partial circuit, should ensure that loop current can at more than 1mA.
In the present embodiment, each device parameters is as follows:
R1=20K ohm, R2=R3=10K ohm, DW1=14V, DW2=8.2V; Q1 selects SST3906, and Q2 selects SST3904.
Signal output apparatus is used for according to testing result equipment output to the back-end control signal, signal output apparatus comprises resistance R4 and triode Q2, the first end of resistance R4 is connected with the positive pole Vin+ of input voltage, second end of resistance R4 is connected with the collector electrode of triode Q2, the current collection very testing result output Sout of triode Q2.
In the voltage threshold testing circuit that the present embodiment provides, the resistance 4 in signal output apparatus is pull-up resistor, and pull-up resistor can be connected on the positive pole Vin+ of input voltage.
In another embodiment, signal output apparatus comprises resistance R4 and triode Q2, the first end of resistance R4 is connected with the positive pole of output voltage, and second end of resistance R4 is connected with the collector electrode of triode Q2, the current collection very testing result output Sout of triode Q2.
In the voltage threshold testing circuit that the present embodiment provides, the resistance 4 in signal output apparatus, also according to the demand of rear end DC/DC Switching Power Supply or miscellaneous equipment, can be connected on suitable voltage source.
The base stage of triode Q2, is connected with the link of voltage-stabiliser tube DW1 and resistance R2, namely conducting voltage testing circuit is connected to signal output apparatus, conducting voltage testing result is converted to suitable level signal and exports.
Signal output apparatus design parameter is as follows:
R4=10K ohm, Q2 selects SST3904.
Shutoff voltage testing circuit, for detecting shutoff voltage threshold value, comprises the triode Q1 of series connection, voltage-stabiliser tube DW2 and resistance R3.
Resistance R3 is connected with testing result output Sout, namely shutoff voltage testing circuit is connected to signal output apparatus, shutoff voltage testing result is converted to suitable level signal and exports.
The computational methods of shutoff voltage threshold value V2 are as follows:
V2＝Vin-Vz2-Vce
Wherein Vin is input voltage, Vz2 be voltage-stabiliser tube DW2 puncture voltage, Vce is the voltage Vce=0.3V between the collector electrode of voltage-stabiliser tube DW2 and emitter.
Shutoff voltage testing circuit parameter is as follows:
R3=10K ohm, DW2=8.2V, Q1 select SST3906.
Shutoff voltage threshold value is lower than conducting voltage threshold value.
In actual applications, the difference of shutoff voltage threshold value and conducting voltage threshold value is minimum can be more than 0.5V, and in the present embodiment, the difference of shutoff voltage threshold value and conducting voltage threshold value is 6V.
The voltage threshold testing circuit course of work that the present embodiment provides is as follows:
When input voltage vin drops to shutoff voltage threshold value V2, Q1 will work in off state, and the pressure drop of DW1 two ends steps to 14V by about 0.3V; This signal directly acts on (positive feedback) conducting voltage testing circuit, and make the base current of Q2 directly be reduced to below cut-off current, Q2 ends fast; It is high level that final Q2 exports by low level signal saltus step.
When input voltage vin rises to conducting voltage threshold value V1, conducting voltage detects output signal and triode Q2 will be made to be in saturation conduction operating state, and the output of Q2 is the low level after conducting by high level saltus step when turning off; The low level signal of Q2 acts on (positive feedback) Q1 and conducting voltage testing circuit through R3, DW2 loop simultaneously, the base current of rapid increase Q2, make Q2 export maintenance and stablize low level, for rear end DC/DC Switching Power Supply or miscellaneous equipment provide reliably control signal.
In actual condition, the work of DC/DC Switching Power Supply or miscellaneous equipment will cause Vin input voltage to produce fluctuation, as long as the pressure reduction between conducting voltage V1 and shutoff voltage V2 is reasonable in design, just can avoid exporting the fluctuation of control signal in critical point.
When input voltage vin rises to conducting voltage threshold value V1, export Continuity signal;
Be less than conducting voltage threshold value V1 when input voltage vin drops to, but when being greater than shutoff voltage threshold value V2, still export Continuity signal;
When input voltage vin drops to shutoff voltage threshold value V2, export cut-off signals;
Be greater than shutoff voltage threshold value V2 when input voltage vin rises to, but when being less than conducting voltage threshold value V1, still export cut-off signals.
More than describe preferred embodiment of the present utility model in detail.Should be appreciated that the ordinary skill of this area just can make many modifications and variations according to design of the present utility model without the need to creative work.Therefore, all technical staff in the art according to design of the present utility model on the basis of existing technology by logic analysis, reasoning or limited to the technical scheme obtained, all should by the determined protection range of claims.
Claims (9)
1. a voltage threshold testing circuit, it is characterized in that, described voltage threshold testing circuit comprises conducting voltage testing circuit, shutoff voltage testing circuit and signal output apparatus, described shutoff voltage testing circuit is connected across between described conducting voltage testing circuit and described signal output apparatus, described conducting voltage testing circuit is for detecting conducting voltage threshold value, described shutoff voltage testing circuit is for detecting shutoff voltage threshold value, and described signal output apparatus is used for according to testing result equipment output to the back-end control signal.
2. voltage threshold testing circuit as claimed in claim 1, it is characterized in that, described conducting voltage testing circuit comprises resistance R1, voltage-stabiliser tube DW1 and the resistance R2 of series connection.
3. voltage threshold testing circuit as claimed in claim 2, it is characterized in that, described signal output apparatus comprises resistance R4 and triode Q2, the described first end of resistance R4 is connected with the positive pole of input voltage, second end of described resistance R4 is connected with the collector electrode of described triode Q2, the current collection very testing result output Sout of described triode Q2.
4. voltage threshold testing circuit as claimed in claim 2, it is characterized in that, described signal output apparatus comprises resistance R4 and triode Q2, the described first end of resistance R4 is connected with the positive pole of output voltage, second end of described resistance R4 is connected with the collector electrode of described triode Q2, the current collection very testing result output Sout of described triode Q2.
5. the voltage threshold testing circuit as described in claim 3 or 4, is characterized in that, the base stage of described triode Q2, is connected with the link of described voltage-stabiliser tube DW1 and described resistance R2.
6. voltage threshold testing circuit as claimed in claim 5, it is characterized in that, described shutoff voltage testing circuit comprises triode Q1, voltage-stabiliser tube DW2 and the resistance R3 of series connection.
7. voltage threshold testing circuit as claimed in claim 6, it is characterized in that, described resistance R3 is connected with described testing result output Sout.
8. voltage threshold testing circuit as claimed in claim 1, it is characterized in that, described shutoff voltage threshold value is lower than described conducting voltage threshold value.
9. voltage threshold testing circuit as claimed in claim 1, it is characterized in that, the difference of described shutoff voltage threshold value and described conducting voltage threshold value is more than or equal to 0.5V.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420860602.XU CN204392078U (en) | 2014-12-25 | 2014-12-25 | A kind of voltage threshold testing circuit |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201420860602.XU CN204392078U (en) | 2014-12-25 | 2014-12-25 | A kind of voltage threshold testing circuit |
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| CN204392078U true CN204392078U (en) | 2015-06-10 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108198558A (en) * | 2017-12-28 | 2018-06-22 | 电子科技大学 | A kind of audio recognition method based on CSI data |
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2014
- 2014-12-25 CN CN201420860602.XU patent/CN204392078U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108198558A (en) * | 2017-12-28 | 2018-06-22 | 电子科技大学 | A kind of audio recognition method based on CSI data |
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