CN2836295Y - Under-voltage protection circuit for vehicular mobile terminal - Google Patents
Under-voltage protection circuit for vehicular mobile terminal Download PDFInfo
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- CN2836295Y CN2836295Y CN 200520088032 CN200520088032U CN2836295Y CN 2836295 Y CN2836295 Y CN 2836295Y CN 200520088032 CN200520088032 CN 200520088032 CN 200520088032 U CN200520088032 U CN 200520088032U CN 2836295 Y CN2836295 Y CN 2836295Y
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Abstract
The utility model discloses an under-voltage protection circuit for a vehicular mobile terminal, which comprises an accumulator cell and a DC/DC converting chip, wherein a voltage output end of the accumulator cell supplies a vehicular mobile television with working power supply after DC voltage which is output by the accumulator cell receives level conversion from the DC/DC converting chip, a reference voltage end and a soft start control end of the DC/DC converting chip are connected with an ON-OFF control circuit which detects the DC voltage output by the accumulator cell. When the voltage output by the accumulator cell is lower than 20V, the soft start control end of the DC/DC converting chip is grounded so as to ensure the normal power utilization of an automobile. Consequently, the output of the chip is switched off, the power supply for auxiliary apparatus, such as the vehicular mobile television, is stopped so as to save the energy of the accumulator cell and ensure the basic functions of the automobile. The under-voltage protection circuit of the utility model has the advantage of effective and simple structure, ensures the normal operation of the automobile, and also has under-voltage protection for the accumulator cell.
Description
Technical field
The utility model relates to a kind of power circuit of vehicle mobile terminals, specifically, is the under-voltage protecting circuit of realizing vehicle mobile terminals.
Background technology
At present, automobile storage battery is divided into diesel locomotive 24V storage battery and gasoline locomotive 12V storage battery.Storage battery provides electric power for automotive ignition, illumination, sound equipment, air-conditioning, vehicle-mounted mobile TV etc.Realize with the 24V voltage transformation being the power circuit of 12V voltage for using L4970/4977 type DC/DC converter, its minimum input voltage can be 15V, because its maximum duty cycle can reach 90%, so, even input 15V direct voltage, still can guarantee normal 12V voltage output, for vehicle-mounted mobile TV provides the stable power power supply.But for the diesel engine locomotive, when battery tension was lower than 20V, basic functions such as the igniting in the automobile, illumination, air-conditioning will be affected, even can't realize.Therefore, in order not to be damaged at low-voltage time protection automobile storage battery, should guarantee preferentially that the electricity consumption of automobile self is normal, this need cut off other supply lines or stop power supply, so the under-voltage protecting circuit that needs design to assist is realized.
Summary of the invention
The utility model is in order to solve in the prior art when the automobile storage battery output voltage is low; if do not cut off the in-car TV power supply; will cause the realization of automobile basic function to be affected; even the problem of damage storage battery; a kind of under-voltage protecting circuit of novel vehicle mobile terminals is provided; by simple circuit configuration, solved the under-voltage protection problem of 24V storage battery, guaranteed the reliable realization of automobile basic function.
For solving the problems of the technologies described above, the utility model is achieved by the following technical solutions:
A kind of under-voltage protecting circuit of vehicle mobile terminals, comprise the DC/DC conversion chip, the voltage input end of described DC/DC conversion chip receives the direct voltage of storage battery output, it is carried out level conversion after, provide working power by its dc voltage output end for vehicle-mounted mobile TV; Soft start control end at described DC/DC conversion chip is connected with an ON-OFF control circuit, and the control end of described ON-OFF control circuit connects the voltage output end of storage battery, and switching gate end one end connects the soft start control end of DC/DC conversion chip, other end ground connection; When the output voltage of storage battery is lower than set point, described ON-OFF control circuit action, the soft start control end ground connection of control DC/DC conversion chip.
As further qualification to technique scheme, in described ON-OFF control circuit, include a positive-negative-positive triode, the base stage of described positive-negative-positive triode connects the voltage output end of storage battery on the one hand through divider resistance, on the other hand through another divider resistance ground connection, its emitter connects the reference voltage terminal of described DC/DC conversion chip, and collector electrode is through the grounding through resistance of two series connection.The connected node of described series resistance links to each other with the base stage of a NPN type triode, and the collector electrode of described NPN type triode connects the soft start control end of DC/DC conversion chip, grounded emitter.
As further limiting again to technique scheme, between the reference voltage terminal of described DC/DC conversion chip and ground and be connected with a filter capacitor respectively between soft start control end and the ground, its dc voltage output end is connected the power end of vehicle-mounted mobile TV with filter circuit through an inductance.
As further limiting again to technique scheme, the model of described DC/DC conversion chip is L4970A, the set point of storage battery output voltage is 20V, the reference voltage value of the reference voltage terminal output of DC/DC conversion chip is 5.1V, the resistance that is connected the divider resistance between the voltage output end of the base stage of positive-negative-positive triode and storage battery is 22.4K Ω, and the resistance of the divider resistance that is connected between the base stage of positive-negative-positive triode and the ground is 10K Ω.
Compared with prior art; advantage of the present utility model with good effect is: the utility model is by being connected ON-OFF control circuit on the reference voltage terminal of DC/DC conversion chip and soft start control end; direct voltage to storage battery output detects; when it is lower than 20V; normal for guaranteeing automobile self electricity consumption; soft start control end ground connection with the DC/DC conversion chip; thereby turn-off chip output; stop power supply to auxiliary equipment such as in-car TVs; save storage battery energy with this; guarantee the realization of automobile basic function, simultaneously storage battery has also been played the under-voltage protection effect.
Description of drawings
Fig. 1 is the schematic diagram of the utility model vehicle mobile terminals under-voltage protecting circuit.
Embodiment
Below in conjunction with the drawings and specific embodiments the utility model is done explanation in further detail.
The utility model employing model is that the DC/DC level transferring chip N801 of L4970A realizes the level conversion of the 24V of storage battery to 12V.Among Fig. 1,14 pin of DC/DC level transferring chip N801 are reference voltage terminal Vref, and the reference voltage of chip internal is 5.1V; 12 pin are soft start control end Softstart, when this pin level is put when low, and the PWM control section no-output of chip N801 inside, its dc voltage output end is with zero setting, and chip N801 enters the under-voltage protection state.Utilize these characteristics of chip N801, on its 12 pin and 14 pin, be connected an ON-OFF control circuit, output voltage to storage battery detects, when the output voltage of storage battery is lower than 20V, the current potential of the soft start control end Soft start of chip N801 is dragged down, turn-off the external output of chip N801, and then avoid the excessive use of battery tension, guarantee the normal of automobile self electricity consumption.
Based on this thought, the utility model has designed ON-OFF control circuit as shown in Figure 1.In described ON-OFF control circuit, the base stage of positive-negative-positive triode Q801 connects the voltage output end XP801 of storage battery through divider resistance R801, R806, and through divider resistance R802 ground connection, its emitter connects the reference voltage terminal Vref of described DC/DC level transferring chip N801, and collector electrode is through resistance R 811, R812 ground connection.The connected node of described resistance R 811, R812 links to each other with the base stage of a NPN type triode Q802 (its model is 2SC1815), the collector electrode of described NPN type triode Q802 connects the soft start control end Soft start of DC/DC level transferring chip N801, grounded emitter.
Utilize the level state of the 14 pin Vref of DC/DC level transferring chip N801 to be the 5.1V of benchmark, the conduction voltage drop of positive-negative-positive triode Q801 (its model is 2SA1015) is 0.7V, so when the base stage level of positive-negative-positive triode Q801 was higher than 5.8V, it was in cut-off state; When the base stage level of positive-negative-positive triode Q801 was lower than 5.8V, it was in conducting state.The conducting of triode Q801 makes its collector potential clamped in about 5.1V, under the dividing potential drop effect of resistance R 811, R812, make NPN type triode Q802 conducting, the soft start control end Soft start of DC/DC level transferring chip N801 is changed to low level, thereby the output Output of chip N801 is turn-offed, stop power-switching circuit work, avoid the energy of storage battery to take.
Come the resistance of divider resistance R801, R806 and R802 is set according to the 20V under-voltage protection magnitude of voltage of setting.The resistance of resistance R 802 is set at 10K Ω, when triode Q801 critical conduction, voltage on the resistance R 802 is 5.1+0.7=5.8V, its electric current is 5.8 ÷ 10=0.58mA, so resistance R 801 is (20-5.8) ÷ 0.58 ≈ 22.4K Ω with the resistance sum of R806, the resistance of resistance R 801 is set to 22K Ω, and then the resistance of resistance R 806 is 0.4K Ω.
Stable for 12 pin and the 14 pin voltages that guarantee DC/DC level transferring chip N801, be connected with filter capacitor C805 and C804 between 12 pin and the ground and between 14 pin and the ground respectively.Resistance R 811, R812 are provided with in order to prevent NPN type triode Q802 overcurrent.When battery tension is normally exported, described DC/DC level transferring chip N801 is converted to 12V with the 24V direct voltage of storage battery output, connect power output end XP802 by its output Output through inductance L 801, and then provide required working power for vehicle-mounted mobile TV.
The utility model has been realized under-voltage protection to storage battery by adopting above-mentioned simple circuit configuration, has guaranteed the reliable realization of automobile basic function.Certainly; above-mentioned explanation is not to be to restriction of the present utility model; the utility model also is not limited in above-mentioned giving an example, and variation, remodeling, interpolation or replacement that those skilled in the art are made in essential scope of the present utility model also should belong to protection range of the present utility model.
Claims (10)
1. the under-voltage protecting circuit of a vehicle mobile terminals, comprise the DC/DC conversion chip, the voltage input end of described DC/DC conversion chip receives the direct voltage of storage battery output, after it is carried out level conversion, provide working power by its dc voltage output end for vehicle-mounted mobile TV, it is characterized in that: the soft start control end at described DC/DC conversion chip is connected with an ON-OFF control circuit, the control end of described ON-OFF control circuit connects the voltage output end of storage battery, switching gate end one end connects the soft start control end of DC/DC conversion chip, other end ground connection; When the output voltage of storage battery is lower than set point, described ON-OFF control circuit action, the soft start control end ground connection of control DC/DC conversion chip.
2. the under-voltage protecting circuit of vehicle mobile terminals according to claim 1; it is characterized in that: in described ON-OFF control circuit, include a positive-negative-positive triode; the base stage of described positive-negative-positive triode connects the voltage output end of storage battery on the one hand through divider resistance; on the other hand through another divider resistance ground connection; its emitter connects the reference voltage terminal of described DC/DC conversion chip; collector electrode connects the control end of a switch element; gating end one end of described switch element connects the soft start control end of DC/DC conversion chip, other end ground connection.
3. the under-voltage protecting circuit of vehicle mobile terminals according to claim 2; it is characterized in that: described switch element adopts a NPN type triode to realize; the base stage of described NPN type triode connects the collector electrode of positive-negative-positive triode; the collector electrode of NPN type triode connects the soft start control end of DC/DC conversion chip, grounded emitter.
4. the under-voltage protecting circuit of vehicle mobile terminals according to claim 3 is characterized in that: the base stage of described NPN type triode connects the collector electrode of positive-negative-positive triode through a resistance, and through another grounding through resistance.
5. the under-voltage protecting circuit of vehicle mobile terminals according to claim 4 is characterized in that: be connected with a filter capacitor between the reference voltage terminal of described DC/DC conversion chip and ground.
6. according to the under-voltage protecting circuit of claim 4 or 5 described vehicle mobile terminals, it is characterized in that: the soft start control end of described DC/DC conversion chip is through a filter capacitor ground connection.
7. the under-voltage protecting circuit of vehicle mobile terminals according to claim 6; it is characterized in that: the set point of described storage battery output voltage is 20V; the reference voltage value of the reference voltage terminal output of DC/DC conversion chip is 5.1V; the resistance that is connected the divider resistance between the voltage output end of the base stage of positive-negative-positive triode and storage battery is 22.4K Ω, and the resistance of the divider resistance that is connected between the base stage of positive-negative-positive triode and the ground is 10K Ω.
8. the under-voltage protecting circuit of vehicle mobile terminals according to claim 7, it is characterized in that: the dc voltage output end of described DC/DC conversion chip is connected the power end of vehicle-mounted mobile TV with filter circuit through inductance.
9. the under-voltage protecting circuit of vehicle mobile terminals according to claim 7 is characterized in that: the output voltage of described storage battery is+24V direct voltage.
10. the under-voltage protecting circuit of vehicle mobile terminals according to claim 8 is characterized in that: it is that the integrated chip of L4970A is realized that described DC/DC conversion chip adopts a model.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200520088032 CN2836295Y (en) | 2005-10-28 | 2005-10-28 | Under-voltage protection circuit for vehicular mobile terminal |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200520088032 CN2836295Y (en) | 2005-10-28 | 2005-10-28 | Under-voltage protection circuit for vehicular mobile terminal |
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| Publication Number | Publication Date |
|---|---|
| CN2836295Y true CN2836295Y (en) | 2006-11-08 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN 200520088032 Expired - Fee Related CN2836295Y (en) | 2005-10-28 | 2005-10-28 | Under-voltage protection circuit for vehicular mobile terminal |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102795116A (en) * | 2011-05-24 | 2012-11-28 | 上海华普汽车有限公司 | Intelligent protective circuit and intelligent protective method for storage battery of hybrid power automobile |
| CN103092313A (en) * | 2013-01-31 | 2013-05-08 | 四川省绵阳西南自动化研究所 | Power management device used for computer equipment in vehicle electronic system |
-
2005
- 2005-10-28 CN CN 200520088032 patent/CN2836295Y/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102795116A (en) * | 2011-05-24 | 2012-11-28 | 上海华普汽车有限公司 | Intelligent protective circuit and intelligent protective method for storage battery of hybrid power automobile |
| CN102795116B (en) * | 2011-05-24 | 2014-07-09 | 上海华普汽车有限公司 | Intelligent protective circuit and intelligent protective method for storage battery of hybrid power automobile |
| CN103092313A (en) * | 2013-01-31 | 2013-05-08 | 四川省绵阳西南自动化研究所 | Power management device used for computer equipment in vehicle electronic system |
| CN103092313B (en) * | 2013-01-31 | 2015-09-23 | 四川省绵阳西南自动化研究所 | A kind of electric power controller for in-vehicle electronic system Computer equipment |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C19 | Lapse of patent right due to non-payment of the annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |