CN204258261U - A kind of converter high accuracy input undervoltage protection circuit - Google Patents
A kind of converter high accuracy input undervoltage protection circuit Download PDFInfo
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- CN204258261U CN204258261U CN201420826719.6U CN201420826719U CN204258261U CN 204258261 U CN204258261 U CN 204258261U CN 201420826719 U CN201420826719 U CN 201420826719U CN 204258261 U CN204258261 U CN 204258261U
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Abstract
The utility model is specifically related to a kind of high accuracy input undervoltage protection circuit for interchanger, mainly comprises: sample circuit, voltage stabilizing circuit, comparison circuit, switching circuit.Described sample circuit comprises the first resistance R1, the first divider resistance R2, the second divider resistance R3 and the first filter capacitor C1; Described voltage stabilizing circuit comprises pressurizer U2, the second filter capacitor C2 and the first current-limiting resistance R6; Described comparison circuit comprises comparator U1A and the second current-limiting resistance R4; Described comparison circuit comprises comparator U1A and the second current-limiting resistance R4.The beneficial effects of the utility model: the utility model is simple and reliable, precision is high, provide the protection of reliable input undervoltage to converter, improve the safety and stability of converter.
Description
Technical field
The utility model relates to a kind of protective circuit, is specifically related to a kind of high accuracy input undervoltage protection circuit for interchanger.
Background technology
Converter is the device that information information source sent is undertaken by certain object converting, and usually adopts PWM IC to control whole power supply, ensures the value of stable output.And converter generally needs input undervoltage protection circuit to ensure the stable of circuit and safety.Present under-voltage protecting circuit more complicated, cost is high.
Utility model content
For the deficiency that prior art exists, the purpose of this utility model is to provide a kind of converter high accuracy input undervoltage protection circuit, for converter provides reliable input undervoltage to protect.
For achieving the above object, the utility model can be achieved by the following technical programs:
A kind of converter high accuracy input undervoltage protection circuit, comprising:
Sample circuit, exports sampling voltage;
Voltage stabilizing circuit, output reference voltage;
Comparison circuit, receives and compares sampling voltage and reference voltage, output level;
Switching circuit, controls its conducting and cut-off by the output level of described comparison circuit;
Described sample circuit comprises the first resistance R1, the first divider resistance R2, the second divider resistance R3 and the first filter capacitor C1, one end of described resistance R1 connects voltage input end Vin+, the other end is by the first divider resistance R2 ground connection, described second divider resistance R3 and the first filter capacitor C1 is in parallel with the first divider resistance R2 respectively, and the node between described resistance R1 and the first divider resistance R2 is connected to the negative input end of comparison circuit;
Described voltage stabilizing circuit comprises pressurizer U2, the second filter capacitor C2 and the first current-limiting resistance R6, the plus earth of described pressurizer U2, its negative electrode is connected to power voltage input terminal VCC by the first current-limiting resistance R6, and described second filter capacitor C2 is in parallel with pressurizer U2;
Described comparison circuit comprises comparator U1A and the second current-limiting resistance R4, and described second current-limiting resistance R4 one end is connected to the node between voltage-stabiliser tube U2 and the first current-limiting resistance R4, and the other end is connected to the positive input terminal of comparator U1A;
Described switching circuit comprises NPN type triode Q1 and the 3rd current-limiting resistance R7, described 3rd current-limiting resistance R7 one end connects the output of comparator U1A, the other end connects the base stage of NPN type triode Q1, the collector electrode of described NPN type triode Q1 connects the compensation level end comp of the PWM IC of converter, the grounded emitter of described NPN type triode Q1.
In above-mentioned technical scheme; comparator is utilized to compare reference voltage and sampled voltage; when sampled voltage is less than set point; comparator U1A negative input end voltage is less than positive input terminal voltage, and comparator overturns, and exports high level; make NPN type triode conducting; be pulled down to by the COMP of PWM IC compensation pin and be less than 1V, IC turns off output, reaches the object of input undervoltage protection.
Further, described comparison circuit also comprises the RC circuit composed in parallel by the second resistance R5 and electric capacity C3, and described RC circuit on one side connects the positive input terminal of comparator U1A, and the other end connects the output of comparator U1A, prevents fluctuation and misoperation.
Further, described comparison circuit also comprises the diode D1 be arranged between comparator U1A and the 3rd current-limiting resistance R7, the anode of described diode D1 connects the output of comparator U1A, its negative electrode serial connection the 3rd current-limiting resistance R7, makes the output level of comparison circuit can only one-way conduction.
Further, described comparison circuit also comprises the second pull down resistor R6 and the 4th filter capacitor C4, and one end of described second pull down resistor R6 connects the negative electrode of diode D1, other end ground connection, described 4th filter capacitor C4 is in parallel with the second pull down resistor R6, prevents comparison circuit misoperation.
Further, described switching circuit also comprises the 3rd pull down resistor R8 and the 3rd filter capacitor C5, and described 3rd filter capacitor C5 one end is connected with the base stage of NPN type triode Q1, other end ground connection, described 3rd pull down resistor R8 is in parallel with the 3rd filter capacitor C5, prevents triode Q1 misoperation.
Further, described pressurizer U2 is adjustable three terminal integrated voltage stabilizer, comprises anode, negative electrode and adjustable side.
The beneficial effects of the utility model: the utility model is simple and reliable, precision is high, provide the protection of reliable input undervoltage to converter, improve the safety and stability of converter.
Accompanying drawing explanation
Fig. 1 is circuit theory schematic diagram of the present utility model.
Embodiment
Below in conjunction with accompanying drawing and embodiment, the utility model is further described:
As shown in Figure 1, converter high accuracy input undervoltage protection circuit described in the utility model, mainly comprises sample circuit, voltage stabilizing circuit, comparison circuit and switching circuit.
Sample circuit, for exporting accurate sampling voltage, comprises the first resistance R1, the first divider resistance R2, the second divider resistance R3 and the first filter capacitor C1.Resistance R1, the first divider resistance R2 and the second divider resistance R3 are voltage sampling resistor, one end of resistance R1 connects voltage input end Vin+, the other end is by the first divider resistance R2 ground connection, second divider resistance R3 and the first filter capacitor C1 is in parallel with the first divider resistance R2 respectively, first filter capacitor C1 stablizes sampling voltage, prevent sampling voltage to fluctuate, make sampling voltage value more accurate.Node between resistance R1 and the first divider resistance R2 is connected to the negative input end of the comparator U1B of comparison circuit 3.The setting of the first resistance R1, the first divider resistance R2 and the second divider resistance R3 comes from under-voltage protection value, Vin+=2.49* (1+R1/ (R2*R3)/(R2+R3)).
Voltage stabilizing circuit, for the 2.49V reference voltage of stable output, comprises pressurizer U2, the second filter capacitor C2 and the first current-limiting resistance R6.Preferably, pressurizer U2 selects adjustable three terminal integrated voltage stabilizer, comprises anode, negative electrode and adjustable side.The plus earth of pressurizer U2, its negative electrode is connected to power voltage input terminal VCC by the first current-limiting resistance R6, and the first current-limiting resistance R6 protects pressurizer U2, makes the operating current of pressurizer U2 within specification limit.Second filter capacitor C2 is in parallel with pressurizer U2, and stable reference voltage prevents reference voltage to fluctuate, and makes reference voltage value more accurate.
Comparison circuit, for receiving and comparing sampling voltage and reference voltage, outputs level signals, comprises comparator U1A, diode D1, the second current-limiting resistance R4, the second resistance R5, electric capacity C3, the second pull down resistor R6 and the 4th filter capacitor C4.Second current-limiting resistance R4 one end is connected to the node between voltage-stabiliser tube U2 and the first current-limiting resistance R6, and the other end is connected to the negative input end of comparator U1A.The anode of diode D1 connects the output of comparator U1A, its negative electrode serial connection the 3rd current-limiting resistance R7.One end of second pull down resistor R6 connects the negative electrode of diode D1, other end ground connection.4th filter capacitor C4 is in parallel with the second pull down resistor R6.Second resistance R5 and electric capacity C3 forms RC parallel circuits, and one end connects the positive input terminal of comparator U1A, and the other end connects the output of comparator U1A.
Switching circuit, controls its conducting and cut-off by the output level of comparison circuit, comprises NPN type triode Q1, the 3rd current-limiting resistance R7, the 3rd filter capacitor C5 and the 3rd pull down resistor R8.3rd current-limiting resistance R7 one end connects the negative electrode of diode D1, and the other end connects the base stage of NPN type triode Q1.3rd filter capacitor C5 one end is connected with the base stage of NPN type triode Q1, other end ground connection, and the 3rd pull down resistor R8 is in parallel with the 3rd filter capacitor C5.The collector electrode of NPN type triode Q1 connects the compensation level end comp of the PWM IC of converter, grounded emitter.
In the present embodiment; comparator U1B compares reference voltage and sampled voltage; when sampled voltage is less than set point; comparator U1A negative input end voltage is less than positive input terminal voltage (2.49V), and comparator overturns, and exports high level; make NPN type triode conducting; be pulled down to by the COMP of PWM IC compensation pin and be less than 1V, IC turns off output, reaches the object of input undervoltage protection.
For a person skilled in the art, according to above technical scheme and design, other various corresponding change and distortion can be made, and all these change and distortion all should belong within the protection range of the utility model claim.
Claims (6)
1. a converter high accuracy input undervoltage protection circuit, is characterized in that, comprising:
Sample circuit, exports sampling voltage;
Voltage stabilizing circuit, output reference voltage;
Comparison circuit, receives and compares sampling voltage and reference voltage, output level;
Switching circuit, controls its conducting and cut-off by the output level of described comparison circuit;
Described sample circuit comprises the first resistance (R1), the first divider resistance (R2), the second divider resistance (R3) and the first filter capacitor (C1), one end of described resistance (R1) connects voltage input end (Vin+), the other end is by the first divider resistance (R2) ground connection, described second divider resistance (R3) and the first filter capacitor (C1) are in parallel with the first divider resistance (R2) respectively, and the node between described resistance (R1) and the first divider resistance (R2) is connected to the negative input end of comparison circuit;
Described voltage stabilizing circuit comprises pressurizer (U2), the second filter capacitor (C2) and the first current-limiting resistance (R6), the plus earth of described pressurizer (U2), its negative electrode is connected to power voltage input terminal (VCC) by the first current-limiting resistance (R6), and described second filter capacitor (C2) is in parallel with pressurizer (U2);
Described comparison circuit comprises comparator (U1A) and the second current-limiting resistance (R4), described second current-limiting resistance (R4) one end is connected to the node between voltage-stabiliser tube (U2) and the first current-limiting resistance (R6), and the other end is connected to the positive input terminal of comparator (U1A);
Described switching circuit comprises NPN type triode (Q1) and the 3rd current-limiting resistance (R7), described 3rd current-limiting resistance (R7) one end connects the output of comparator (U1A), the other end connects the base stage of NPN type triode (Q1), the collector electrode of described NPN type triode (Q1) connects the compensation level end (comp) of the PWM IC of converter, the grounded emitter of described NPN type triode (Q1).
2. converter high accuracy input undervoltage protection circuit according to claim 1; it is characterized in that: described comparison circuit also comprises the RC circuit composed in parallel by the second resistance (R5) and electric capacity (C3); described RC circuit on one side connects the positive input terminal of comparator (U1A), and the other end connects the output of comparator (U1A).
3. converter high accuracy input undervoltage protection circuit according to claim 1; it is characterized in that: described comparison circuit also comprises the diode (D1) be arranged between comparator (U1A) and the 3rd current-limiting resistance (R7); the anode of described diode (D1) connects the output of comparator (U1A), its negative electrode serial connection the 3rd current-limiting resistance (R7).
4. converter high accuracy input undervoltage protection circuit according to claim 3; it is characterized in that: described comparison circuit also comprises the second pull down resistor (R6) and the 4th filter capacitor (C4); one end of described second pull down resistor (R6) connects the negative electrode of diode (D1); other end ground connection, described 4th filter capacitor (C4) is in parallel with the second pull down resistor (R6).
5. converter high accuracy input undervoltage protection circuit according to claim 1; it is characterized in that: described switching circuit also comprises the 3rd pull down resistor (R8) and the 3rd filter capacitor (C5); described 3rd filter capacitor (C5) one end is connected with the base stage of NPN type triode (Q1); other end ground connection, described 3rd pull down resistor (R8) is in parallel with the 3rd filter capacitor (C5).
6., according to described converter high accuracy input undervoltage protection circuit arbitrary in Claims 1 to 5, it is characterized in that: described pressurizer (U2) is adjustable three terminal integrated voltage stabilizer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420826719.6U CN204258261U (en) | 2014-12-23 | 2014-12-23 | A kind of converter high accuracy input undervoltage protection circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420826719.6U CN204258261U (en) | 2014-12-23 | 2014-12-23 | A kind of converter high accuracy input undervoltage protection circuit |
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| CN204258261U true CN204258261U (en) | 2015-04-08 |
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| CN201420826719.6U Active CN204258261U (en) | 2014-12-23 | 2014-12-23 | A kind of converter high accuracy input undervoltage protection circuit |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104852277A (en) * | 2015-04-22 | 2015-08-19 | 常州华达科捷光电仪器有限公司 | Drive circuit used for laser module, and laser projector with drive circuit |
| CN106208656A (en) * | 2016-09-05 | 2016-12-07 | 株洲中车时代电气股份有限公司 | A kind of DC source under-voltage protective module |
-
2014
- 2014-12-23 CN CN201420826719.6U patent/CN204258261U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104852277A (en) * | 2015-04-22 | 2015-08-19 | 常州华达科捷光电仪器有限公司 | Drive circuit used for laser module, and laser projector with drive circuit |
| CN106208656A (en) * | 2016-09-05 | 2016-12-07 | 株洲中车时代电气股份有限公司 | A kind of DC source under-voltage protective module |
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