The control device of low current loss
Technical field
The utility model relates to a kind of control device of low current loss, relates in particular to a kind ofly to use centrifugal switch to do initial control and use the control device of A-battery as power supply.
Background technology
Wheel type vehicle regular meeting under steam has the contingency situation of blowing out that (account for freeway accident accident 6%) takes place, and the reason that causes blowing out is the stress problems of tire itself mostly.Tire is subjected to the external force influence or the variation of weather of environment under steam for a long time, and then causes the wearing and tearing and the distortion of tire itself, and these all can have influence on the pressure of tire and the safety of driving.In addition, when driving or improper inflation, the pressure that also can influence inside tires changes.Because the carelessness of driving is not done suitable tire maintenance or is used tire gauge to check the pressure condition of tire, so the contingency that regular meeting blows out in vehicle ' on time.Moreover, keep normal pressure of tire more can save fuel consumption.Therefore, the tire pressure of wheel type vehicle detects of crucial importance for the safety of vehicle '.
Please refer to Fig. 1, Fig. 1 is the circuit diagram of traditional tire pressure detector.Tire pressure detector 1 utilizes centrifugal switch SW1 to respond to the speed of a motor vehicle, when road speed during greater than a certain setting speed of a motor vehicle, centrifugal switch SW1 can close (CLOSE), and then the leakage current switching circuit action that transistor Q12 and transistor Q11 are formed, and forms holding circuit 12.Under the speed of a motor vehicle of normal driving, battery 10 provides voltage to use to controller 14 by holding circuit 12 and forward diode D11, and this controller 14 can be used for detecting tire pressure, temperature, acceleration and cell voltage etc.Battery 10 also charges to charging capacitor C13 by holding circuit 12 and forward diode D11 simultaneously.When the speed of a motor vehicle slows down and makes that centrifugal switch SW1 opens (OPEN), because holding circuit 12 has moved, so controller 14 still can continuous service.When the speed of a motor vehicle drops to set point, controller 14 can be exported low-potential signal "off" transistor Q12 and Q11 in regular turn, removes action to control this holding circuit 12, in order to stop battery 10 supply voltages to this controller 14, at this moment, the operating voltage VDD of controller 14 comes from charging capacitor C13.
In traditional tire pressure detector 1, controller 14 is coupled to battery 10 by forward diode D11.When battery 10 supply voltages are given controller 14, can produce pressure drop on the forward diode D11, this pressure drop meeting influences battery 10 power supplies and gives the size of controller 14 operating voltage VDD, and influences its power supply quality, and quickens to shorten the useful life of battery 10.Moreover in traditional tire pressure detector 1, transistor Q12 and transistor Q11 are bipolar transistor (Bipolar Transistor), bipolar transistor is when open-circuit condition, and its open-circuit impedance is a few K Ω, therefore when open circuit, leakage current is very big, and its current sinking is also very big when work.So, use bipolar transistor also can quicken to shorten the useful life of battery 10.
Summary of the invention
In view of this, the utility model provides the control device of kind of low current loss, is to use MOS transistor to replace traditional bipolar transistor, and, controller is directly to be coupled to battery by the MOS switch, and the output of controller has increased driver element and is used for removing self-insurance action.
The control device of the utility model low current loss comprises: battery; Centrifugal switch is coupled to this battery; Control switch is coupled to this centrifugal switch, and this control switch is controlled by this centrifugal switch; Self-holding switch is coupled to this battery and this control switch, and this self-holding switch is controlled by this control switch; Controller is coupled to this self-holding switch; Driver element is coupled to this controller, and this driver element is controlled by this controller; Let out the energy switch, be coupled to this driver element, this is let out and can be controlled by this driver element by switch, and by this control switch.
According to the control device of described low current loss, this control switch is a MOS transistor, and the gate terminal of this control switch is coupled to this centrifugal switch, the source terminal ground connection of this control switch.
According to the control device of described low current loss, this control switch is the N-MOS transistor.
Control device according to described low current loss, this self-holding switch is a MOS transistor, the gate terminal of this self-holding switch is coupled to the drain electrode end of this control switch, and the source terminal of this self-holding switch is coupled to this battery, and the drain electrode end of this self-holding switch is coupled to this controller.
According to the control device of described low current loss, this self-holding switch is the P-MOS transistor.
According to the control device of described low current loss, this is let out can switch be MOS transistor, and this gate terminal of letting out the energy switch is coupled to this driver element, and this drain electrode end of letting out the energy switch is coupled to the gate terminal of this control switch, and this lets out the source terminal ground connection of energy switch.
According to the control device of described low current loss, this is let out can switch be the N-MOS transistor.
According to the control device of described low current loss, this driver element includes: forward diode, and its anode tap is coupled to this controller; Charging capacitor is coupled to the cathode terminal of this forward diode; And discharge resistance, be coupled to this charging capacitor.
According to the control device of described low current loss, this controller is a wireless tire pressure detector.
According to the control device of described low current loss, this wireless tire pressure detector is for detecting the wireless tire pressure detector of tire pressure, temperature, acceleration and cell voltage.Utilize the present invention, can reduce operating current and leakage current, increase operating voltage VDD, all right may command capacitor discharge time guarantees all can make under any load and temperature conditions holding circuit to end.
In order further to understand the utility model feature and technology contents, see also following about detailed description of the present utility model and accompanying drawing, yet accompanying drawing only provide with reference to and the explanation usefulness, be not to be used for the utility model is limited.
Description of drawings
Fig. 1 is the circuit diagram of traditional tire pressure detector; And
Fig. 2 is the control device circuit diagram of the utility model low current loss.
Wherein, description of reference numerals is as follows:
(tradition)
1 tire pressure detector
The SW1 centrifugal switch
Q11, Q12 transistor
12 holding circuits
10 batteries
The D11 forward diode
14 controllers
The C13 charging capacitor
(the utility model)
The control device of 2 low current loss
20 batteries
22 holding circuits
24 controllers
26 driver elements
The Q21 self-holding switch
The Q22 control switch
Q23 lets out can switch
The SW2 centrifugal switch
Embodiment
Please refer to Fig. 2, be the control device circuit diagram of the utility model low current loss.The control device 2 of low current loss comprises: battery 20, centrifugal switch SW2, control switch Q22, self-holding switch Q21, controller 24, driver element 26 and let out can switch Q23.Centrifugal switch SW2 is coupled to this battery 20, and control switch Q22 is coupled to this centrifugal switch SW2, and this control switch Q22 is controlled by this centrifugal switch SW2.Self-holding switch Q21 is coupled to this battery 20 and this control switch Q22, and this self-holding switch Q21 is controlled by this control switch Q22.Controller 24 is coupled to this self-holding switch Q21.Driver element 26 is coupled to this controller 24, and this driver element 26 is controlled by this controller 24.Let out and can be coupled to this driver element 26 by switch Q23, this is let out and can be controlled by this driver element 26 by switch Q23, and by this control switch Q22.Controller 24 is embodied as wireless tire pressure detector.
With reference to figure 2, wherein this control switch Q22 is the N-MOS transistor again, and the gate terminal (G2) of this control switch Q22 is coupled to this centrifugal switch SW2, source terminal (S2) the coupling earth terminal G of this control switch Q22.This self-holding switch Q21 is the P-MOS transistor, the gate terminal (G1) of this self-holding switch Q21 is coupled to the drain electrode end (D2) of this control switch Q22, the source terminal (S1) of this self-holding switch Q21 is coupled to this battery 20, and the drain electrode end (D1) of this self-holding switch Q21 is coupled to this controller 24.This is let out can switch Q23 be the N-MOS transistor, this gate terminal (G3) of letting out energy switch Q23 is coupled to this driver element 26, this drain electrode end (D3) of letting out energy switch Q23 is coupled to the gate terminal (G2) of this control switch Q22, and this source terminal (S3) of letting out energy switch Q23 is coupled to this ground end G.Wherein this driver element 26 includes: the anode tap of forward diode D21 is coupled to this controller 24; Charging capacitor C23 is coupled to the cathode terminal of this forward diode D21; And discharge resistance R26 is coupled to this charging capacitor C23.
Again with reference to figure 2, the utility model is to be that load illustrates with the wireless tire pressure detector, and when road speed during greater than a certain setting speed of a motor vehicle, centrifugal switch SW2 can close (CLOSE), and then make control switch Q22 and self-holding switch Q21 conducting in regular turn, and form holding circuit 22 via resistance R 25.Even after this moment, centrifugal switch SW2 opened (OPEN), control switch Q22 and self-holding switch Q21 still can conducting, the not influences that opened by centrifugal switch SW2.Under the speed of a motor vehicle of normal driving, battery 20 provides operating voltage VDD to use to controller 24 by self-holding switch Q21, and this controller 24 is to be used for detecting tire pressure, temperature, acceleration and cell voltage etc.
When the speed of a motor vehicle slows down and makes that centrifugal switch SW2 opens (OPEN), because holding circuit 22 has moved, so controller 24 still can continuous service.When the speed of a motor vehicle drops to a set point, controller 24 can be drawn high output voltage to control this driver element 26, make this driver element 26 drive this and let out energy switch Q23 conducting, letting out of conducting can end control switch Q22 and self-holding switch Q21 by switch Q23 in regular turn, to remove the action of this holding circuit 22, in order to stop battery 20 supply voltage VDD to this controller 24.When removing holding circuit 22 actions, control switch Q22 and self-holding switch Q21 can end (OFF) in regular turn, the power supply of letting out energy switch Q23 this moment can be provided by the capacitor C in the driver element 26 23, and the power supply on the capacitor C 23 is set up through forward diode D21 by the high voltage of controller 24 outputs, and be the RC time constant decision by discharge resistance R26 and charging capacitor C23 its settling time.
So can keep let out can switch the conducting of Q23, the generation of so-called breech lock (Latch) phenomenon may or take place with what guarantee that control switch Q22 and self-holding switch Q21 do not have a conducting again.
In sum, the utility model has the feature of following progress with respect to conventional art:
1. operating current and leakage current reduce:
The design of traditional circuit is to utilize bipolar transistor (Bipolar Transistor) to be used as switch to use, because the design load of the bias resistance of bipolar transistor is about K Ω, so the current sinking of bipolar transistor when work is about tens of mA, and the leakage current of bipolar transistor after closing is about tens of uA.Yet, in the utility model, be to utilize MOS transistor to be used as switch to use, because the design load of the bias resistance of MOS transistor is about M Ω, so the current sinking of MOS transistor when work is about tens of uA, and the leakage current of MOS transistor after closing is about tens of nA.So leakage current and conventional art when current sinking when the utility model uses MOS transistor work and inoperative all can reduce by contrast.
2. increase operating voltage VDD:
Traditional design is to utilize diode D11 to stop the discharge path of capacitor C 13, so can make the operating voltage VDD that offers controller 14 reduce about 0.4~0.9V (40~125 ℃) than battery 10 voltages, so, life of product is reduced.Yet, design of the present utility model is to increase MOS transistor Q23, capacitor C 23 and resistance R 26, and use diode D21 to stop the discharge path of capacitor C 23, make the utility model offer controller 24 operating voltage VDD can with battery 20 voltages substantially identical (40~125 ℃), so, life of product is reduced.
3. may command capacitor discharge time, guarantee under any load and temperature conditions, all can make holding circuit to end:
Traditional design utilizes 14 discharges of 13 pairs of controllers of capacitor C, and its discharge time is by the load size decision of controller 14, uncontrollable its time of designer, when load is excessive, capacitor C 13 can be discharged too fast, causes holding circuit to end, or needs big electric capacity (indicating) keep voltage.Yet, the utility model uses 26 discharges of 23 pairs of resistance R of capacitor C, and its discharge time, the designer can come the control time by the product size of capacitor C 23 and resistance R 26 by the product size decision of capacitor C 23 and resistance R 26, irrelevant with the load size, do not need big electric capacity to keep voltage yet.
Yet the above only is the detailed description and the accompanying drawing of the preferable specific embodiment of the utility model, any those skilled in the art, think easily and variation or modify all can be encompassed in the scope that claim of the present utility model defines.