CN101089771A - Constant-current voltqage limit power supply with output protection - Google Patents
Constant-current voltqage limit power supply with output protection Download PDFInfo
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- CN101089771A CN101089771A CN 200610051985 CN200610051985A CN101089771A CN 101089771 A CN101089771 A CN 101089771A CN 200610051985 CN200610051985 CN 200610051985 CN 200610051985 A CN200610051985 A CN 200610051985A CN 101089771 A CN101089771 A CN 101089771A
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Abstract
A constant current and voltage limited power supply with output protection is prepared as forming bias circuit by bias resistance and clamping diode, forming constant current circuit by constant current tube and current sampling resistance as well as current limitation triode, forming protection circuit by current limitation resistance and protective triode as well as protective diode.
Description
Technical field
The invention belongs to field of power supplies, especially relate to a kind of constant current pressure limiting power supply with output protection.
Technical background
At present in the test to cable performance, need will be online cable cut off the power supply, test again after adding a low-voltage dc power supply to cable then.If before test, forget to the cable outage, will moment damage testing tool.
Summary of the invention
Purpose of the present invention overcomes the deficiencies in the prior art exactly, and a kind of constant current pressure limiting power supply with protection is provided, and makes cable open circuit, short circuit, civil power is arranged, have under the various situations such as recoil surge etc. and can not damage testing apparatus.
The present invention includes constant current tube Q1, the drain electrode of constant current tube Q1 connects D.C. regulated power supply, and current sampling resistor R2 one end is connected with the source electrode of constant current tube Q1, and an other end is connected with the anode of protection diode D1; The emitter of electric current restriction triode Q2 is connected with the anode of protection diode D1, and base stage is connected with the source electrode of constant current tube Q1, and collector is connected with the grid of constant current tube Q1; The anode of clamp diode D2 is connected with the grid of constant current tube Q1, and negative electrode is connected with the anode of protection diode D1; Biasing resistor R4 one end is connected to power supply, and an other end is connected to the grid of constant current tube Q1; The emitter of protection triode Q3 is connected to the anode of protection diode D1, and collector is connected to the grid of constant current tube Q1; The end of current-limiting resistance R6 is connected to ground wire, and an other end is connected to the base stage of protection triode Q3; The negative electrode of protection diode D1 is as the output of power supply.
The base voltage of described electric current restriction triode Q2 is less than cut-in voltage U
tThe time, the complete conducting of constant current tube Q1; When greater than cut-in voltage, electric current restriction triode Q2 opens, and the gate source voltage of constant current tube Q1 is by electric current restriction triode Q2 bypass, and output current no longer increases, and enter constant current state this moment, and the continuous current of output equals:
The gate source voltage of described constant current tube Q1 is prevented that by clamp diode D2 clamper constant current tube Q1 is damaged.
When mains supply is arrived in misconnection,, then protect diode D1 anti-inclined to one side, constant current pressure limiting source no-output electric current if the line voltage forward surpasses inner voltage limiting value; If the line voltage negative sense surpasses threshold values, then protect triode Q3 to obtain the electric current conducting because of base stage, this moment constant current tube Q1 the grid source between protected triode Q3 short circuit, constant current source stops output.
The present invention also can increase other protecting component, and the antisurge element is as inductance, voltage dependent resistor (VDR) etc.
The function of protection triode Q3, current-limiting resistance R6 among the present invention can the working voltage comparer, optocoupler is realized.
Constant current pressure limiting source circuit of the present invention possesses perfect holding circuit, and no matter short circuit, short circuit, forward overvoltage, negative sense overvoltage all can not damage internal circuit, forgets before the test in original technology that to cable outage will damage the problem of testing tool if overcome.
Description of drawings
Fig. 1 is a circuit diagram of the present invention;
Electric current, voltage curve synoptic diagram when Fig. 2 is a load change in resistance of the present invention;
Output current and voltage concerned synoptic diagram when Fig. 3 was a misconnection civil power of the present invention.
Embodiment
As shown in Figure 1, a kind of constant current pressure limiting source with output protection, it is made up of biasing circuit, continuous current, holding circuit.Biasing circuit is made up of biasing resistor R4, clamp diode D2.Constant-current circuit is made up of constant current tube Q1, current sampling resistor R2, electric current restriction triode Q2.Holding circuit is made up of current-limiting resistance R6, protection triode Q3 and protection diode D1.The drain electrode of constant current tube Q1 connects D.C. regulated power supply, and current sampling resistor R2 one end is connected with the source electrode of constant current tube, and an other end is connected with the anode of protection diode D1.The emitter of electric current restriction triode Q2 is connected with the anode of protection diode D1, and base stage is connected with the source electrode of constant current tube Q1, and collector is connected with the grid of constant current tube Q1.The anode of clamp diode D2 is connected with the grid of constant current tube Q1, and negative electrode is connected with the anode of protection diode D1.Biasing resistor R4 one end is connected to power supply, and an other end is connected to the grid of constant current tube Q1.The emitter of protection triode Q3 is connected to the anode of protection diode D1, and collector is connected to the grid of constant current tube Q1.The end of current-limiting resistance R6 is connected to ground wire, and an other end is connected to the base stage of protection triode Q3.The negative electrode of protection diode D1 is as the output of power supply.
Biasing circuit: biasing resistor R4 is connected to 17V, and than the high 5V of drain voltage of constant current tube Q1, and the cut-in voltage of one field effect transistor is 4.5V, it is hereby ensured that constant current tube Q1 can fully open when output 12V.Clamp diode D2 is used to limit gate source voltage and is no more than the maximal value that constant current tube Q1 can bear.When civil power was arrived in misconnection, the P point voltage can become negative value, if also not action of protection this moment triode Q3, then clamp diode D2 conducting guarantees that gate source voltage is in the limit range of constant current tube Q1.
Constant-current circuit: when electric current limited the not enough cut-in voltage of base voltage (being generally 0.6V) of triode Q2, the complete conducting of constant current tube Q1 was operated in the pressure limiting state this moment; When electric current restriction triode Q2 base voltage surpassed the 0.6V left and right sides, electric current restriction triode Q2 opened, and the gate source voltage of constant current tube Q1 can be limited the collector bypass of triode Q2 by electric current, and enter constant current state this moment, and the continuous current of output equals:
Holding circuit: when mains supply is arrived in misconnection,, then protect diode D1 anti-inclined to one side, constant current pressure limiting source no-output electric current if the line voltage forward surpasses inner voltage limiting value.If the line voltage negative sense surpasses threshold values, then protect triode Q3 to obtain the electric current conducting because of base stage, this moment constant current tube Q1 the grid source between protected triode Q3 short circuit, constant current source stops output.
Electric current, voltage curve synoptic diagram when Fig. 2 is the load change in resistance; Fig. 3 when the misconnection civil power output current and voltage concern synoptic diagram, wherein Q3 works in 1 district, output is under an embargo; The D2 conducting prevents that the Q1 gate source voltage from overstepping the extreme limit, still constant current in 2 districts; Normal constant current output in 3 districts; D1 is anti-inclined to one side in 4 districts, the no-output electric current.Constant current pressure limiting power supply of the present invention has following several state:
As Fig. 2, non-loaded or load is very light, this moment, inner DC voltage was equivalent to be applied directly in the load, and pressure condition exceeds; The very heavy or short circuit of load, enter constant current state this moment, and output voltage can reduce with holding current constant.
As Fig. 3, the misconnection civil power, civil power is in positive period, then protects diode D1 to end, constant current source no-output electric current; Misconnection civil power, civil power are in negative cycle and voltage ratio is less, then clamp diode D2 conducting, and output remains constant current, but general power is in the scope that element can bear; Misconnection civil power, civil power are in negative cycle and voltage ratio is bigger, then protects triode Q3 conducting, makes that voltage is 0 between grid-source of constant current tube Q1, and constant current tube Q1 ends, the constant current source no-output.
Claims (2)
1, the constant current pressure limiting power supply of band output protection, it is characterized in that this constant current pressure limiting power supply comprises constant current tube (Q1), the drain electrode of constant current tube (Q1) connects D.C. regulated power supply, current sampling resistor (R2) end is connected with the source electrode of constant current tube (Q1), and an other end is connected with the anode of protection diode (D1); The emitter of electric current restriction triode (Q2) is connected with the anode of protection diode (D1), and base stage is connected with the source electrode of constant current tube (Q1), and collector is connected with the grid of constant current tube (Q1); The anode of clamp diode (D2) is connected with the grid of constant current tube (Q1), and negative electrode is connected with the anode of protection diode (D1); Biasing resistor (R4) end is connected to power supply, and an other end is connected to the grid of constant current tube (Q1); The emitter of protection triode (Q3) is connected to the anode of protection diode (D1), and collector is connected to the grid of constant current tube (Q1); One end of current-limiting resistance (R6) is connected to ground wire, and an other end is connected to the base stage of protection triode (Q3); The negative electrode of protection diode (D1) is as the output of power supply.
2, the constant current pressure limiting power supply of band output protection as claimed in claim 1, the base voltage that it is characterized in that described electric current restriction triode (Q2) is less than cut-in voltage U
tThe time, constant current tube (Q1) conducting fully; When greater than cut-in voltage, electric current restriction triode (Q2) is opened, and the gate source voltage of constant current tube (Q1) is limited triode (Q2) bypass by electric current, and output current no longer increases, and enter constant current state this moment, and the continuous current of output equals:
The gate source voltage of described constant current tube (Q1) is prevented that by clamp diode (D2) clamper constant current tube (Q1) is damaged.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200610051985 CN101089771A (en) | 2006-06-15 | 2006-06-15 | Constant-current voltqage limit power supply with output protection |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200610051985 CN101089771A (en) | 2006-06-15 | 2006-06-15 | Constant-current voltqage limit power supply with output protection |
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| Publication Number | Publication Date |
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| CN101089771A true CN101089771A (en) | 2007-12-19 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 200610051985 Pending CN101089771A (en) | 2006-06-15 | 2006-06-15 | Constant-current voltqage limit power supply with output protection |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103279057A (en) * | 2013-04-28 | 2013-09-04 | 许昌许继晶锐科技有限公司 | Analog acquisition channel protection circuit and analog acquisition system |
| CN104518652A (en) * | 2014-12-26 | 2015-04-15 | 广东威创视讯科技股份有限公司 | Output voltage negative overshoot suppression device and method for DC-DC switching circuit |
| CN112000165A (en) * | 2020-04-24 | 2020-11-27 | 昆山启康医疗器械有限公司 | Graded adjustable constant current source with high-voltage output capability |
| CN113659644A (en) * | 2021-01-19 | 2021-11-16 | 青岛鼎信通讯股份有限公司 | Super capacitor charging management circuit with temperature control function |
-
2006
- 2006-06-15 CN CN 200610051985 patent/CN101089771A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103279057A (en) * | 2013-04-28 | 2013-09-04 | 许昌许继晶锐科技有限公司 | Analog acquisition channel protection circuit and analog acquisition system |
| CN103279057B (en) * | 2013-04-28 | 2018-09-07 | 许昌许继晶锐科技有限公司 | Analog acquisition passage protects circuit and analog collection system |
| CN104518652A (en) * | 2014-12-26 | 2015-04-15 | 广东威创视讯科技股份有限公司 | Output voltage negative overshoot suppression device and method for DC-DC switching circuit |
| CN112000165A (en) * | 2020-04-24 | 2020-11-27 | 昆山启康医疗器械有限公司 | Graded adjustable constant current source with high-voltage output capability |
| CN113659644A (en) * | 2021-01-19 | 2021-11-16 | 青岛鼎信通讯股份有限公司 | Super capacitor charging management circuit with temperature control function |
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