阅读说明：本技术 一种闪光器快速启动电路及控制方法 (Flash device quick start circuit and control method ) 是由 方建平 郭晋亮 赵启东 于 2019-11-05 设计创作，主要内容包括：本发明提供了一种闪光器快速启动电路及控制方法,开关KEY默认断开状态,电池无法向电路供电,灯泡不亮,当按键KEY闭合后,电池为电路供电,前半个周期内逻辑模块LOG控制NMOS管Q1断开,灯泡灭,电池为电容C1充电,后半个周期内逻辑模块LOG控制NMOS管Q1导通,灯泡被点亮；二极管D1为逻辑模块LOG模块供电,保持LOG模块对NMOS管的持续控制。本发明在无需对芯片的等效电阻进行严苛设计的情况下,在上电的第一个周期内迅速点亮灯泡,同时有效的保护芯片,防止芯片在工作初期损毁。本发明沿用经典的电路,即无需现有电路的外围进行重新设计,仅需对控制逻辑进行优化即可实现,降低了项目的研发成本。(The invention provides a flash device quick start circuit and a control method, wherein a switch KEY is in a default disconnection state, a battery cannot supply power to a circuit, a bulb cannot be lighted, when the KEY KEY is closed, the battery supplies power to the circuit, a logic module LOG controls an NMOS (N-channel metal oxide semiconductor) tube Q1 to be disconnected in the first half period, the bulb is extinguished, the battery charges a capacitor C1, the logic module LOG controls an NMOS tube Q1 to be connected in the second half period, and the bulb is lighted; the diode D1 supplies power to the LOG module of the logic module to keep the LOG module continuously controlling the NMOS tube. The invention can quickly light the bulb in the first power-on period without strictly designing the equivalent resistance of the chip, and effectively protect the chip and prevent the chip from being damaged in the initial working period. The invention continues to use the classical circuit, namely the periphery of the existing circuit is not required to be redesigned, and the control logic is only required to be optimized to realize the classical circuit, thereby reducing the research and development cost of the project.)

1. A flash quick start circuit, characterized by:

the flash quick start circuit comprises a battery BAT, a chip IC, a capacitor C1, a bulb L1 and a switch KEY, wherein the battery BAT is a vehicle-mounted storage battery and supplies power to the whole circuit; the capacitor C1 is a bootstrap capacitor and is connected with the IC in parallel, and supplies power to the IC within the lighting time of the bulb; the IC has an internal structure that an NMOS tube Q1 is connected with a logic control module LOG in parallel, the anode of a diode is connected with the drain electrode of an NMOS tube Q1, and the cathode of the diode is connected with a bootstrap capacitor C1; the bulb is a luminous part of the flasher circuit, one end of the bulb is connected to a source electrode of an NMOS tube in the IC, and the other end of the bulb is directly connected to a negative electrode of the battery BAT; the KEY is an integral switch of the flasher circuit and is connected between the negative electrode of the battery and the ground, the battery supplies power to the whole circuit when the KEY is closed, and the battery is disconnected from the circuit when the KEY is disconnected.

2. A flash fast start circuit as claimed in claim 1, wherein:

after the flash quick start circuit is connected, the switch KEY defaults to a disconnected state, the battery cannot supply power to the circuit, the bulb cannot be lighted, when the KEY KEY is closed, the battery supplies power to the circuit, the logic module LOG controls the NMOS tube Q1 to be disconnected in the first half period, the bulb is turned off, the battery charges the capacitor C1, the logic module LOG controls the NMOS tube Q1 to be connected in the second half period, and at the moment, the battery is directly connected to the two sides of the bulb, and the bulb is lighted; because the NMOS tube Q1 is conducted, the capacitor has a bootstrap phenomenon, the diode D1 supplies power to the LOG module of the logic module, the LOG module keeps continuous control over the NMOS tube, the circuit works normally, and the process is repeated in the next period.

3. A control method using the flash fast start circuit of claim 1, comprising the steps of:

the chip IC adopts overcurrent protection, after a switch KEY of the circuit is closed, the first half period of the battery BAT supplies power to the IC and charges a capacitor C1, when the second half period is entered, a logic module LOG drives an NMOS tube Q1 to be switched on, when the current exceeds a threshold value set by the overcurrent protection, the overcurrent protection of the chip is immediately triggered to be switched off, the NMOS is switched off, no current flows on the chip and the bulb, a delay time t is preset in the circuit, the t is 1/20-1/1000 of the switching-on period, at the time t after the overcurrent protection is triggered, the logic module LOG in the circuit generates a high level signal again to drive the NMOS tube Q1, the circuit is restarted again and is continuously repeated, a high level signal is generated at the time t to drive the NMOS tube Q1, the circuit is restarted again until the current does not trigger the overcurrent protection of the chip any more, and the bulb can be rapidly heated to the lighting temperature, and normal operation is started.

Technical Field

The invention relates to the field of electronics, in particular to a starting method of a flasher.

Background

With the rapid development of road construction and the improvement of the living standard of residents in China, motor vehicles gradually become necessities in the life of people, and with the rapid increase of the number of the motor vehicles, the road safety also becomes a popular social topic. In the safety guarantee system of the motor vehicle, a flashing light system is undoubtedly an important part, and flashing lights including a steering light and double flashes can send corresponding warning information to other vehicles, so that it is necessary to ensure that flashers of the vehicles can be started at any time.

The circuit system of the flasher is simple, and the whole circuit can be simplified into the following four parts: the device comprises a battery, an IC, a capacitor and a bulb, wherein the vehicle-mounted storage battery supplies power for the circuit; the control IC performs logic control of the circuit; capacitor C1 charges when it is off and powers the IC during the light up process. When the circuit is conducted, the logic control module controls the switching tube to be conducted, the pressure difference occurs at the two ends of the bulb, a large amount of heat can be rapidly accumulated on the filament due to the fact that the resistance value of the filament is small, when a certain temperature point is reached, the bulb can emit visible light, and the bulb can be considered to be lighted at the moment.

However, due to the physical limitation of the chip itself, designers need to perform corresponding protective limiting measures during IC design, and there are two common methods: and an over-current protection and over-temperature protection mechanism of the chip. According to the light-emitting mechanism, the bulb can generate enough power to start to emit light only by needing larger power, the current at the initial electrifying stage is larger because the resistance value of the heating wire of the bulb is positively correlated with the temperature, the overcurrent protection point of the chip is easily reached to cause the power tube of the chip to be turned off, and if the overcurrent protection mechanism of the chip is cancelled, the large current passes through the chip to generate huge heat in extreme time to cause the chip to be burnt.

The method for solving the problem at the present stage is to reduce the equivalent resistance value on the chip as much as possible through circuit design and manufacturing process, and keep the on state in the first conducting time of the circuit, so that the heating wire of the bulb is heated rapidly, and the electric bulb has small heat productivity of the chip due to the small equivalent resistance of the chip, and meanwhile, the chip can rapidly dissipate the generated heat due to good heat dissipation capacity, thereby ensuring that the chip is not burnt out.

This design can ensure that the chip is turned on quickly during the first cycle of power-up, but due to the high requirements on chip design and manufacture, the chip requires a larger design area and a better package, which increases the manufacturing cost of the chip, and such a design approach may be irreparable today when the chip is increasingly competitive. Meanwhile, due to the process deviation of chip design, in order to ensure the yield of chips, enough design margin needs to be reserved, and the design and manufacturing cost is further increased.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a flash quick start circuit and a control method. On the basis of keeping the concise design of the circuit of the existing flasher, the control mode of the circuit is modulated to realize rapid start in the first period of electrification, and meanwhile, the chip is effectively protected to prevent the circuit from being burnt out due to overheating and overcurrent.

The technical scheme adopted by the invention for solving the technical problems is as follows:

a flash quick start circuit comprises a battery BAT, a chip IC, a capacitor C1, a bulb L1 and a switch KEY, wherein the battery BAT is a vehicle-mounted storage battery and supplies power to the whole circuit; the capacitor C1 is a bootstrap capacitor and is connected with the IC in parallel, and supplies power to the IC within the lighting time of the bulb; the IC has an internal structure that an NMOS tube Q1 is connected with a logic control module LOG in parallel, the anode of a diode is connected with the drain electrode of an NMOS tube Q1, and the cathode of the diode is connected with a bootstrap capacitor C1; the bulb is a luminous part of the flasher circuit, one end of the bulb is connected to a source electrode of an NMOS tube in the IC, and the other end of the bulb is directly connected to a negative electrode of the battery BAT; the KEY is an integral switch of the flasher circuit and is connected between the negative electrode of the battery and the ground, the battery supplies power to the whole circuit when the KEY is closed, and the battery is disconnected from the circuit when the KEY is disconnected.

After the flash quick start circuit is connected, the switch KEY defaults to a disconnected state, the battery cannot supply power to the circuit, the bulb cannot be lighted, when the KEY KEY is closed, the battery supplies power to the circuit, the logic module LOG controls the NMOS tube Q1 to be disconnected in the first half period, the bulb is turned off, the battery charges the capacitor C1, the logic module LOG controls the NMOS tube Q1 to be connected in the second half period, and at the moment, the battery is directly connected to the two sides of the bulb, and the bulb is lighted; because the NMOS tube Q1 is conducted, the capacitor has a bootstrap phenomenon, the diode D1 supplies power to the LOG module of the logic module, the LOG module keeps continuous control over the NMOS tube, the circuit works normally, and the process is repeated in the next period.

The invention also provides a control method related to the flash quick start circuit, which comprises the following steps:

the chip IC adopts overcurrent protection, after a switch KEY of the circuit is closed, the first half period of the battery BAT supplies power to the IC and charges a capacitor C1, when the second half period is entered, a logic module LOG drives an NMOS tube Q1 to be switched on, when the current exceeds a threshold value set by the overcurrent protection, the overcurrent protection of the chip is immediately triggered to be switched off, the NMOS is switched off, no current flows on the chip and the bulb, a delay time t is preset in the circuit, the t is 1/20-1/1000 of the switching-on period, at the time t after the overcurrent protection is triggered, the logic module LOG in the circuit generates a high level signal again to drive the NMOS tube Q1, the circuit is restarted again and is continuously repeated, a high level signal is generated at the time t to drive the NMOS tube Q1, the circuit is restarted again until the current does not trigger the overcurrent protection of the chip any more, and the bulb can be rapidly heated to the lighting temperature, and normal operation is started.

The invention has the advantages that the bulb can be quickly lightened in the first power-on period without strictly designing the equivalent resistance of the chip, and the chip is effectively protected and prevented from being damaged in the initial working period. The physical design of the invention continues to use the classical circuit, namely does not need to redesign the periphery of the existing circuit, and can be realized only by optimizing the control logic, thereby reducing the research and development cost of the project.

Drawings

Fig. 1 is a circuit of the flash start method of the present invention.

FIG. 2 is a diagram showing the relationship between the temperature and the resistance of the lamp according to the present invention.

Fig. 3 is a schematic diagram showing a short circuit in the overcurrent protection mode of the present invention.

Fig. 4 shows the current situation in the actual operation of the circuit of the present invention.

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

The invention improves the logic control module of the circuit, solves the problem that the cold lamp of the flasher can not be started or is slowly started under the condition of not changing the physical design of the circuit, and can effectively prevent the chip from being burnt out at the initial stage of electrifying.

A flash unit rapid start circuit is provided, a hardware circuit of which is shown in figure 1 and comprises a battery BAT, a chip IC, a capacitor C1, a bulb L1 and a switch KEY, wherein the battery BAT is a vehicle-mounted storage battery, the nominal capacitance value of the battery BAT is 12V, and the battery BAT supplies power to the whole circuit; the capacitor C1 is a bootstrap capacitor and is connected with the IC in parallel, and supplies power to the IC within the lighting time of the bulb; the IC has an internal structure that an NMOS tube Q1 is connected with a logic control module LOG in parallel, the anode of a diode is connected with the drain electrode of an NMOS tube Q1, and the cathode of the diode is connected with a bootstrap capacitor C1; the bulb is a luminous part of the flasher circuit, one end of the bulb is connected to a source electrode of an NMOS tube in the IC, and the other end of the bulb is directly connected to a negative electrode of the battery BAT; the KEY is an integral switch of a flasher circuit, a steering lamp or a double-flash toggle switch in the vehicle and is connected between the negative electrode of the battery and the ground, the battery supplies power to the whole circuit when the KEY is closed, and the battery is disconnected from the circuit when the KEY is disconnected.

After the flash quick start circuit is connected, the switch KEY defaults to a disconnected state, the battery cannot supply power to the circuit, the bulb cannot be lighted, when the KEY KEY is closed, the battery supplies power to the circuit, the logic module LOG controls the NMOS tube Q1 to be disconnected in the first half period, the bulb is turned off, the battery charges the capacitor C1, the logic module LOG controls the NMOS tube Q1 to be connected in the second half period, and at the moment, the battery is directly connected to the two sides of the bulb, and the bulb is lighted; because the NMOS tube Q1 is conducted, the capacitor has a bootstrap phenomenon, the diode D1 supplies power to the LOG module of the logic module, the LOG module keeps continuous control over the NMOS tube, the circuit works normally, and the process is repeated in the next period.

At the moment that the switch KEY is closed in the circuit, because the temperature of the bulb is close to the ambient temperature when the bulb is not lighted, the bulb close to the ambient temperature is defined as a cold lamp, the resistance of the cold lamp is small, and a large current is generated when the battery voltage is applied to two ends of the bulb, the current can flow in the chip IC to trigger the over-current protection (OCP) of the chip, and the over-temperature protection (OTP) of the chip can be rapidly triggered, and the chip can be directly turned off by the two protection measures, so that the bulb cannot be normally lighted in the first period. In order to ensure that the bulb is lighted in the first period in the prior art, the equivalent resistance of the chip is reduced as much as possible through the design and manufacturing process, so that the heating of the chip is reduced as much as possible in the preheating process of the bulb, namely, the chip IC is lighted by heat accumulation in the previous period. Because the heat accumulation of the chip IC is not generated transiently, in order to prevent the chip from burning out caused by overheating, the sensitivity and the prevention position of a temperature detection module in the chip are required to be higher, otherwise, a circuit is damaged before the over-temperature protection module responds, or the circuit cannot be started again after protection, and the reliability and the normal work of a system are influenced.

The invention adopts the overcurrent protection of the chip IC as a protection mechanism, has lower requirement on the placement position of the overcurrent protection, can flexibly adjust according to the equivalent resistance value condition of the chip, and reduces the pressure of chip design and layout. After a switch KEY of the circuit is closed, the first half cycle of a battery BAT supplies power to the IC and charges a capacitor C1, when the second half cycle is started, a logic module LOG drives an NMOS tube Q1 to be connected, the battery BAT is equivalent to be directly connected to two ends of a bulb at the moment, a large current can be generated to flow through a chip due to the fact that the resistance value of a cold lamp is small, when the current exceeds a threshold value set by overcurrent protection, a turn-off mechanism of the chip is triggered immediately, an NMOS is turned off, no current flows on the chip and the bulb, the current directly drops to 0 after the overcurrent protection, the circuit cannot be restarted through hysteresis, the Retry hysteresis time t is preset in the circuit, the t is 1/20-1/1000 of the on time, in the embodiment of the invention, 1ms is taken as an example, and when the t is triggered by the overcurrent protection, the logic module LOG in the circuit generates a high-level signal again to drive the NMOS tube Q1, the circuit is restarted again and is repeated continuously, a high level signal is generated every t moments to drive the NMOS tube Q1, the circuit is restarted again, the temperature on the filament is increased continuously along with the increase of the restarting times, the resistance value of the bulb is correspondingly increased, the current flowing through the circuit is reduced continuously until the current does not trigger the over-current protection of the chip any more, and the bulb can be heated to the lighting temperature rapidly to start normal work.

As shown in fig. 1, the whole flasher circuit comprises a vehicle-mounted battery BAT, a bulb L1, a capacitor C1, an IC and a circuit switch KEY, wherein the voltage value of the battery BAT is 12V, the bulb supplies power when being lighted, and the bulb supplies power to the IC and charges the capacitor C1 when being extinguished; the bulb is a steering lamp or a double-flash lamp on a vehicle, and in order to facilitate the description of a circuit, the working principle of the bulb is an incandescent lamp instead of an LED; as shown in fig. 2, the heating wire of the bulb is a metal conductor, and the resistivity thereof increases with the increase of the temperature and decreases with the decrease of the temperature, so that the resistance value of the bulb increases with the increase of the temperature and decreases with the decrease of the temperature as can be seen from the resistance formula. The capacitor C1 is used for charging when the bulb is turned off and supplying power to the IC in the process of the electric quantity of the bulb, and the value of the capacitor is nF level; for convenience of description, the internal circuit of the IC is simplified into an NMOS transistor Q1 connected in parallel with a capacitor C1, a diode D1 in charge of managing a charge-discharge loop of the capacitor C1, and a logic control module LOG of a circuit core; the switch KEY of the circuit corresponds to a steering lamp or a double-flash toggle switch in an actual vehicle and is responsible for controlling the on-off of the overall circuit, and when the KEY is closed, the overall circuit starts to be electrified and operated.

The specific connection mode of the circuit is as follows: the positive pole of the accumulator BAT is directly connected to the IC, the negative pole of the accumulator is connected to one end of the bulb L1 through the switch KEY, and the point is grounded at the same time; the other end of the bulb is connected to the output of the IC and is also connected to the other side of the capacitor C1, and the connection relationship of the equivalent components in the IC is as follows: the source electrode of the NMOS tube is connected to the positive electrode of the battery, the drain electrode of the NMOS tube is connected with the bulb, and the NMOS tube is responsible for connecting the battery BAT with the bulb L1 when in conduction, the grid electrode of the NMOS tube is connected to the logic control module LOG, the diode is connected between the positive electrode of the power supply and the capacitor, and the direction is from the power supply to the capacitor in forward conduction.

After the circuit is correctly connected, because the switch KEY is in an open state by default, no current path exists in the circuit at this time, namely the circuit does not start to work, and after the switch KEY is closed, the battery starts to supply power to the whole circuit. Because the turn light and the flash light are both in a flashing mode for warning, the invention is explained by the flashing frequency of 1Hz and the duty ratio of 50 percent, and the bulb is not lighted in the first half period of each period, namely the first 500ms, and the bulb is lighted in the second half period. In the first half of the period, the battery is connected to the IC to supply power to the logic circuit LOG, the LOG outputs a low level signal to the grid electrode of the NMOS tube, the NMOS tube is not conducted at the moment, no current passes through the bulb L1, and therefore the bulb can be regarded as a common resistor. Since the forward conduction direction of the diode is from the positive pole of the power supply to the upper plate of the capacitor, a voltage difference equal to the voltage of the storage battery exists on the capacitor at the moment, and the voltage difference is 12V. When entering the next half cycle, the LOG module outputs a high level signal, the NMOS transistor is turned on, and the positive and negative electrodes of the battery are equivalent to the two ends of the bulb L1, so that the two ends of the IC are equivalent to the equal potential, and the battery can no longer supply power to the IC. However, the voltage on the capacitor cannot change suddenly, so that the lower plate potential of the capacitor is changed to 12V relatively at the moment when the switching tube is conducted, the upper plate potential of the capacitor is changed to 24V due to the bootstrap effect of the capacitor, and the capacitor and the IC form a discharge loop due to the existence of the diode D1, so that the capacitor supplies power to the IC in a half period of lighting of the lamp. The capacitor is recharged during the next cycle when the bulb is extinguished.

The resistance value of the filament of the incandescent lamp is in positive correlation with the temperature of the filament, and in the first period of closing the switch KEY, before the switch tube is conducted, the temperature of the bulb is close to the room temperature, and the resistance value of the filament is small at the moment, so that when the voltage of the battery is directly applied to two ends of the bulb, the current flowing through the bulb is large, the instantaneous current exceeds 20A, the current can also flow through the chip, and the overcurrent protection in the chip can be triggered. Meanwhile, due to the limitation of the design area and the manufacturing process of the chip, the equivalent resistance of the chip cannot be too small, the chip can generate heat violently when a large current passes through the chip, and the generated heat cannot be dissipated quickly due to the existence of packaging, so that the heat inside the chip can be accumulated quickly, the temperature of the chip rises sharply, the over-temperature protection of the chip is triggered, and if the response speed of the temperature detection module is not enough or the position where the module is placed is unreasonable, the chip is extremely easy to burn out before the over-temperature protection is triggered. The scheme for solving the problem at the present stage is generally to control the heating condition of the chip through circuit design and packaging process, because the temperature of the filament rises faster when the large current passes through the filament, and the resistance value is correspondingly increased along with the rise of the temperature, the flowing current can be gradually reduced, so that the bulb can be lightened as long as the chip can support the large current in front and the heating condition, and the normal work is started. However, the design requirement of the scheme is high, and meanwhile, due to the normal distribution property of manufacturing, the actual chip equivalent resistance is not completely consistent, more design margins need to be reserved, and the production cost is further increased.

The invention adopts an improved overcurrent protection response mechanism, and realizes the lighting of the circuit in the first power-on period and effectively prevents the chip from being damaged by adjusting the control mode and the protection mechanism of the circuit under the condition of not changing the hardware design of the existing circuit.

Because the current on the chip is transient, the temperature needs a process of accumulation and rise, and the requirement on the chip design and the response speed of the corresponding detection module is higher by adopting an over-temperature protection mechanism, the invention adopts a protection and restart mechanism realized by over-current detection in order to prevent the problem of chip burnout caused by corresponding delay, and the requirement on the chip design layout is lower while the rapidness and the correspondence can be realized.

At the initial stage of circuit power-on, because the resistance value of the bulb is low, the flowing current is large, the overcurrent protection of the chip can be triggered, and the setting of the overcurrent point can be determined according to the chip and a peripheral circuit. To illustrate the over-current protection mechanism of the circuit, the corresponding current situation when the circuit is directly short-circuited is shown in fig. 3. In the first two periods, once overcurrent occurs, the circuit is restarted after the delay time t, which is much shorter than the single period time of the flash, the flash period of the present invention is assumed to be 1s, the delay time is set to be 1ms, as shown in fig. 3, after the circuit is powered on, in the half period of the circuit being turned on, once overcurrent occurs, the circuit is restarted after being turned off for 1ms, which is repeated continuously, and the complete time of the two periods is 2s, if the overcurrent exceeds the time, the turn signal lamp can not be started, which may bring serious safety hazard, and the circuit needs to be redesigned.

And after the current in the circuit exceeds a preset overcurrent point, the MOS tube is switched off, and the chip stops working. Because the current directly drops to 0 after reaching the overcurrent point, a control mode of overcurrent hysteresis does not exist, and a built-in RETRY time t mode is adopted for control, namely after the chip is turned off for a period of time, taking 1ms as an example, the chip is started again, if the overcurrent point is still triggered, the process is repeated, the resistance value of the bulb is increased along with the increase of the turn-on times, the current gradually drops, and finally the overcurrent protection of the chip is not triggered by the current value after power-on, and the circuit is normally turned on, so the current condition of the circuit in actual work is shown in fig. 4. At the initial stage of electrification, because the resistance value of the cold lamp is smaller, the current flowing in the circuit instantly reaches the current limiting state, the circuit is turned off, but in the process, because the current passes through the bulb, the filament can generate heat, and the resistance value is increased; and after 1ms, the circuit is restarted, if the current in the circuit still reaches a current limiting value at the moment, the process is repeated, the resistance is increased again, and the circuit is started normally until the overcurrent does not appear in the circuit due to the resistance value increase during electrification. When the next period comes, the lamp bulb is turned off for only 500ms, so that the temperature of the lamp filament can not change greatly, and the lamp filament can be directly turned on.