TWM566677U - Vehicle lamp control circuit - Google Patents

Abstract

A vehicle lamp control circuit couples with a solid state lighting device, the vehicle lamp control circuit comprises a filter circuit, a first transistor, and a second transistor. The filter circuit comprises an input node and an output node, the input node is arranged to receive a PWM signal, the output node is arranged to provide a switch signal. The first transistor comprises a first node, a second node, and a control node, wherein the second node is arranged to receive a system low voltage, and the control node is arranged to receive the switch signal. The second transistor comprises a first node, a second node, and a control node, wherein the first node is arranged to receive the PWM signal, the second node couples with the solid state lighting device, and the control node couples with the first node of the first transistor. The vehicle lamp control circuit is arranged to control the solid state lighting device according to the PWM signal and the system low voltage provided by an electronic control unit (ECU). When the ECU operates in a detection stage and a duty cycle of the PWM signal is smaller than a predetermined threshold value, voltage value of the switch signal is smaller than a predetermined voltage value, and the first transistor and the second transistor are at off state to make the solid state lighting device operate at off state.

Description

Lamp control circuit

The present disclosure relates to a control circuit, and more particularly to a vehicle lamp control circuit.

At present, the electronic control unit (ECU) on the market detects the various electronic components on the car when the power is turned on but the engine has not yet ignited (that is, the so-called red fire stage), which includes a low load ratio. The pulse width modulation (PWM) signal detects the lamp load to confirm that the lights are properly connected. However, if the vehicle lamp is a light-emitting diode having a lower impedance than the tungsten lamp as a light source, when the LED receives the PWM signal for detection, the light-emitting diode will flicker. At this time, if the car driver observes that the lamp is flickering when the engine has not ignited, the car driving often mistakes the car for malfunction.

In view of this, how to provide a lamp control circuit that can avoid flickering of the lamp in the detection phase of the driving computer is a problem to be solved in the industry.

The vehicle lamp control circuit is coupled to a solid state lighting device, and the vehicle lamp control circuit includes a filter circuit, a first transistor, and a second transistor. The filter circuit includes an input terminal for receiving a PWM signal and an output terminal for providing a switch signal. The first transistor includes a first end, a second end, and a control end, the second end is configured to receive a system low voltage, and the control end is configured to receive the switch signal. The second transistor includes a first end, a second end, and a control end, the first end is configured to receive the PWM signal, the second end is coupled to the solid state light emitting device, and the control end is coupled to the first end The first end of a transistor. Wherein the lamp control circuit is configured to control the solid state lighting device according to the PWM signal provided by the line computer and the low voltage of the system, when the driving computer is in the detecting phase and the load ratio of the PWM signal is less than a preset threshold value, The voltage level of the switch signal is less than a predetermined voltage value, and the first transistor and the second transistor are in an off state to bring the solid state light emitting device into an off state.

The above-mentioned lamp control circuit can prevent the solid-state lighting device from flickering during the detection phase of the driving computer without affecting the detection function of the driving computer.

100,300‧‧‧light control circuit

101‧‧‧ Driving computer

103‧‧‧Solid light-emitting device

110, 310‧‧‧ Filter circuit

112‧‧‧ Receiver

114‧‧‧output

116‧‧‧ Grounding terminal

120‧‧‧First transistor

130‧‧‧Second transistor

140‧‧‧Electrostatic discharge protection components

212‧‧‧First resistance

214‧‧‧second resistance

216‧‧‧first capacitor

318‧‧‧Zina diode

350‧‧‧ Third resistor

360‧‧‧fourth resistor

370‧‧‧Anti-reverse components

372‧‧‧ diode

380‧‧‧second capacitor

410‧‧‧ warning device

N1‧‧‧ first node

N2‧‧‧ second node

PWM‧‧‧ pulse width modulation signal

Vss‧‧‧ system low voltage

Vsw‧‧‧ switch signal

Ifb‧‧‧Return current

To make the above and other objects, features, advantages and embodiments of the disclosed documents more apparent, the description of the drawings is as follows:

1 is a simplified functional block diagram of a vehicle lamp control circuit in accordance with an embodiment of the present disclosure.

Figure 2 is a simplified diagram of an embodiment of the filter circuit of Figure 1 Road map.

Figure 3 is a simplified functional block diagram of a vehicle lamp control circuit in accordance with another embodiment of the present disclosure.

Figure 4 is a simplified functional block diagram of a vehicle light control system in accordance with the present disclosure.

Embodiments of the present disclosure will be described below in conjunction with related drawings. In the drawings, the same reference numerals indicate the same or similar elements or methods.

1 is a simplified functional block diagram of a vehicle lamp control circuit 100 in accordance with an embodiment of the present disclosure. The vehicle light control circuit 100 includes a filter circuit 110, a first transistor 120, a second transistor 130, and an electrostatic discharge (ESD) protection element 140. The vehicle lamp control circuit 100 is coupled between the driving computer 101 and the solid state lighting device 103 for controlling the operation of the solid state lighting device 103 according to the PWM signal provided by the driving computer 101 and the system low voltage Vss. In order to make the drawing simple and easy to explain, other components and connection relationships in the lamp control circuit 100 are not shown in FIG.

The filter circuit 110 includes a receiving end 112, an output end 114 and a grounding end 116. The receiving end 112 and the grounding end 116 are coupled to the driving computer 101, and are respectively configured to receive a PWM signal and a system low voltage Vss, and the output end 114 is used for outputting. Switch signal Vsw. The filter circuit 110 can determine the voltage level of the switch signal Vsw according to the received PWM signal.

The first transistor 120 includes a first end, a second end, and a control The control terminal is coupled to the output end 114 of the filter circuit 110 and configured to receive the switch signal Vsw, and the second end is configured to receive the system low voltage Vss. The second transistor 130 includes a first end, a second end, and a control end. The first end is coupled to the receiving end 112 of the filter circuit 110 and configured to receive the PWM signal, and the second end is coupled to the solid state light emitting device 103. The control end is coupled to the first end of the first transistor 120.

In addition, the ESD protection component 140 is coupled between the receiving end 112 of the filter circuit 110 and the ground.

In practice, the first transistor 120 can be implemented with a variety of suitable N-type transistors, and the second transistor 130 can be implemented with a variety of suitable P-type transistors. The solid state light emitting device 103 can include a light emitting diode (abbreviated as LED). The ESD protection component may comprise a transient voltage suppressor diode (TVS diode).

The operation of the driving computer 101 includes a detection phase and an actuation phase. When the driving computer 101 is in the detecting phase, the driving computer 101 transmits a PWM signal having a lower duty ratio (for example, a PWM signal with a load ratio of 5%) to the vehicle lamp control circuit 100 to detect the vehicle lamp control circuit 100 and solid state lighting. Whether the device 103 is properly connected. For example, when the vehicle lamp control circuit 100 receives the PWM signal, the vehicle lamp control circuit 100 outputs the feedback current Ifb to the driving computer 101 to notify the driving computer 101 that the vehicle lamp control circuit 100 and the solid state lighting device 103 have been properly connected.

In the detection phase of the driving computer 101, the vehicle lamp control circuit 100 also compares the duty ratio of the PWM signal with a preset threshold value. If The load ratio of the PWM signal is less than the preset threshold value, and the vehicle lamp control circuit 100 outputs a switching signal Vsw having a low voltage level (for example, approximate to the system low voltage Vss) to make the first transistor 120 and the second transistor 130 is in an OFF state.

Taking the first transistor 120 as the N-type transistor and the second transistor 130 as the P-type transistor, in the detection phase of the driving computer 101, the difference between the low-voltage level switching signal Vsw and the system low voltage Vss When the value has not reached a sufficient gate-to-source voltage and the first transistor 120 is turned on, the second transistor 130 assumes an OFF state. Therefore, the solid-state light-emitting device 103 is maintained in an off state without flickering.

In this embodiment, the preset threshold value of the vehicle lamp control circuit 100 is set such that the first transistor 120 and the second transistor 130 are in an off state in the detection phase of the driving computer 101. Therefore, in the detection phase of the driving computer 101, the vehicle lamp control circuit 100 can prevent the low-load ratio PWM signal from being transmitted to the solid-state lighting circuit, thereby maintaining the solid-state lighting device 103 in the off state without flickering.

When the driving computer 101 is in the actuation phase, the driving computer 101 transmits a PWM signal having a higher duty ratio (for example, a PWM signal having a duty ratio close to 100%, that is, a DC analog signal) to the vehicle lamp control circuit 100. At this time, the lamp control circuit 100 also compares the duty ratio of the PWM signal with the aforementioned preset threshold value. If the duty ratio of the PWM signal is greater than or equal to the preset threshold value, the vehicle lamp control circuit 100 outputs a switching signal Vsw having a high voltage level (eg, close to the peak value of the PWM signal) to switch the first transistor 120 to be turned on. status. And the first transistor 120 is turned on. In the state, the system low voltage Vss is transmitted to the control terminal of the second transistor 130 through the first transistor 120, so that the second transistor 130 is switched to the on state, and the solid state light emitting device 103 is normally lit.

In the present embodiment, the preset threshold value of the vehicle lamp control circuit 100 is set such that the first transistor 120 and the second transistor 130 are in an on state in the actuation phase of the driving computer 101. Therefore, in the actuation phase of the driving computer 101, the vehicle lamp control circuit 100 transmits the PWM signal to the solid-state lighting device 103 through the second transistor 130, and the solid-state lighting device 103 is in an on state to have a stable luminance.

FIG. 2 is a simplified circuit diagram of an embodiment of the filter circuit 110 according to FIG. 1. The filter circuit 110 includes a first resistor 212, a second resistor 214, and a first capacitor 216. The first resistor 212 includes a first end and a second end, wherein the first end is coupled to the input end 112 of the filter circuit 110, and the second end is coupled to the first node N1. The second resistor 214 includes a first end and a second end. The first end is coupled to the first node N1, the second end is coupled to the ground end 116 of the filter circuit 110, and is configured to receive the system low voltage VSS. The first capacitor 216 includes a first end and a second end, wherein the first end is coupled to the output end 114 of the filter circuit 110 and the first node N1, and the second end is configured to receive the system low voltage VSS.

When the PWM signal during the pulse period (ie, the high voltage level) is transmitted from the input terminal 112 of the filter circuit 110 to the first node N1 via the first resistor 212, a part of the current of the PWM signal flows to the first capacitor 216. The first end of the first capacitor 216 further raises the voltage level of the first terminal of the first capacitor 216. Another part of the PWM signal current flows to the filter circuit via the second resistor 214 The ground terminal 116 of 110, in turn, generates a feedback current Ifb.

On the other hand, when the PWM signal is in the non-pulse period (ie, the low voltage level), the first end of the first capacitor 216 releases the stored charge to the ground terminal 116 of the filter circuit 110 via the second resistor 214.

Therefore, by adjusting the resistance values of the first resistor 212 and the second resistor 214 and adjusting the capacitance value of the first capacitor 216, the aforementioned preset threshold value for comparison with the duty ratio of the PWM signal can be determined.

For example, the first resistor 212 is set to have a smaller resistance value, and the second resistor 214 and the first capacitor 216 are respectively set to have larger resistance values and capacitance values, so that the filter circuit 110 can be made smaller. Preset threshold value. For another example, if the first resistor 212 is set to have a larger resistance value, and the second resistor 214 and the first capacitor 216 are respectively set to have smaller resistance values and capacitance values, the filter circuit 110 can be made to have a larger value. Large preset threshold.

FIG. 3 is a simplified functional block diagram of a vehicle lamp control circuit 300 in accordance with another embodiment of the present disclosure. The vehicle light control circuit 300 is similar to the vehicle light control circuit 100, with the difference that the vehicle light control circuit 300 includes a filter circuit 310, a third resistor 350, a fourth resistor 360, an anti-reverse element 370, and a second capacitor 380. The vehicle light control circuit 300 can also control the operation of the solid state lighting device 103 based on the PWM signal provided by the driving computer 101 and the system low voltage Vss. In order to make the drawings simple and easy to explain, other components and connection relationships in the control device 300 are not shown in FIG.

The filter circuit 310 is similar to the filter circuit 110 except that the filter circuit 310 includes a Zener diode 318. Zener diode The cathode end of the body 318 is coupled to the first node N1, and the anode end is configured to receive the system low voltage Vss. The Zener diode 318 can prevent the PWM signal of abnormal voltage peak from damaging the second resistor 214, the first capacitor 216 or the first transistor 120.

The third resistor 350 includes a first end and a second end, wherein the first end is coupled to the second node N2, and the second end is coupled to the control end of the second transistor 130. The fourth resistor 360 includes a first end and a second end, wherein the first end is coupled to the control end of the second transistor 130, and the second end is coupled to the first end of the first transistor 120. The second node N2 is coupled to the first end of the second transistor 130 and the receiving end 112 of the filter circuit 110.

The anti-reverse element 370 includes a first end and a second end, wherein the first end is coupled to the ESD protection component 140 and is configured to receive a PWM signal, and the second end is coupled to the second node N2.

In addition, the second capacitor 380 includes a first end and a second end, wherein the first end is coupled to the second node N2, and the second end is configured to receive the system low voltage Vss.

In particular, the second capacitor 380 can be used to filter out high frequency noise in the PWM signal, and the anti-reverse element 370 can be used to prevent the lamp control circuit 100 from being damaged due to erroneous reverse input of the PWM signal.

For example, in the case where the voltage at the first end of the anti-reverse element 370 is greater than the voltage at the second end, the anti-reverse element 370 turns on the first end and the second end. When the voltage at the first end of the anti-reverse element 370 is less than the voltage of the second end, the representative PWM signal may be erroneously input into the vehicle lamp control circuit 100 from the ground end 116 of the filter circuit 110. Element 370 will break the first end and the second end.

In practice, the anti-reverse element 370 can be implemented by the diode 372 of FIG. 3, wherein the anode end of the diode 372 is coupled to the ESD protection component 140 and the cathode end is coupled to the second node N2.

In some embodiments, the driving computer 101 can issue an alert when the vehicle light control circuit 100 and the solid state lighting device 103 are not properly connected. For example, referring to FIG. 4, the driving computer 101 is coupled to the vehicle lamp control circuit 100 or 300, and is also coupled to the warning device 410. When the driving computer 101 is in the detecting phase and the PWM signal is in the pulse period (that is, the high voltage level), if the driving computer 101 does not receive the feedback current Ifb generated by the vehicle lamp control circuit 100, the driving computer 101 determines the running light. The control circuit 100 and the solid state lighting device are not properly connected. At this time, the driving computer 101 can control the warning device 410 to generate a predetermined sound, a predetermined light, or a predetermined combination of sound and light to notify the driving to perform troubleshooting.

As can be seen from the above, the vehicle lamp control circuit 100 or 300 can prevent the solid state lighting device 103 from flickering during the detection phase of the driving computer 101 without affecting the detection function of the driving computer 101.

Certain terms are used throughout the description and claims to refer to particular elements. However, those of ordinary skill in the art should understand that the same elements may be referred to by different nouns. The specification and the scope of patent application do not use the difference in name as the way to distinguish the components, but the difference in function of the components as the basis for differentiation. The term "including" as used in the specification and the scope of the patent application is an open term and should be interpreted as "including but not limited to". In addition, "coupled" includes any direct and indirect means of attachment herein. Therefore, if the first element is described in the text The coupling of the second component means that the first component can be directly connected to the second component through a signal connection manner such as electrical connection or wireless transmission, optical transmission, or the like, or indirectly electrically or signal through other components or connection means. Connected to the second component.

The above are only the preferred embodiments of the present invention, and all changes and modifications made in accordance with the requirements of the present invention are within the scope of the present invention.

Claims (10)

A lamp control circuit is coupled to a solid state lighting device. The lamp control circuit includes: a filter circuit including an input end and an output end, the input end is configured to receive a PWM signal, and the output end is configured to provide a switching signal; a first transistor comprising a first end, a second end and a control end, the second end for receiving a system low voltage, the control end for receiving the switch signal; and a first The second transistor includes a first end, a second end, and a control end, the first end is configured to receive the PWM signal, the second end is coupled to the solid state light emitting device, and the control end is coupled to the first end a first end of the transistor; wherein the lamp control circuit is configured to control the solid state lighting device according to the PWM signal provided by the line computer and the low voltage of the system, when the driving computer is in the detecting phase and the PWM signal is loaded When the ratio is less than a preset threshold, the voltage level of the switch signal is less than a predetermined voltage value, and the first transistor and the second transistor are in an off state, so that the solid state light emitting device is in an off state. . The light control circuit of claim 1, wherein when the driving computer is in an actuation phase and the load ratio of the PWM signal is greater than or equal to the preset threshold, the voltage level of the switching signal is greater than or equal to the preset voltage. And the first transistor and the second transistor are in an on state to switch the solid state lighting device to a conducting state. The light control circuit of claim 1, wherein the filter circuit comprises: a first resistor comprising a first end and a second end, the first end coupled to the input end; a second resistor comprising a first end coupled to the second end of the first resistor, the second end is configured to receive the system low voltage, and a first capacitor includes a first end And a second end, the first end is coupled to the output end and the second end of the first resistor, and the second end is configured to receive the system low voltage. The lamp control circuit of claim 3, wherein the filter circuit further comprises: a Zener diode comprising a cathode end and an anode end, the cathode end being coupled to the second end of the first resistor, the anode Extremely used to receive low voltage from the system. The vehicular control circuit of claim 1, further comprising: a third resistor comprising a first end and a second end, the first end being coupled to the first end of the second transistor, the second The end is coupled to the control end of the second transistor; and a fourth resistor includes a first end and a second end, the first end is coupled to the control end of the second transistor, the second The end is coupled to the first electric crystal The first end of the body. The vehicle lamp control circuit of claim 5, further comprising: an anti-reverse element comprising a first end and a second end, wherein the first end is configured to receive the PWM signal, and the second end is coupled to the input And the first end of the second transistor, wherein when the voltage of the first end is greater than the voltage of the second end, the anti-reverse element turns on the first end and the second end, when the first end The voltage is less than the voltage of the second end, and the anti-reverse element opens the first end and the second end. The vehicle lamp control circuit of claim 6, wherein the anti-reverse circuit comprises: a diode comprising a cathode end and an anode end, wherein the anode end is configured to receive the PWM signal, and the cathode end is coupled to the input And the first end of the second transistor. The vehicle lamp control circuit of claim 5, further comprising: a second capacitor comprising a first end and a second end, the first end being coupled to the input end, the second end being configured to receive the system low Voltage. The lamp control circuit of claim 2, wherein the lamp control circuit outputs a feedback current to the driving computer according to the PWM signal. The vehicle lamp control circuit of claim 9, wherein the driving computer is further coupled to a warning device, and if the PWM signal is at a high voltage level and the driving computer does not receive the feedback current, the driving computer controls the warning device to generate A predetermined sound, a predetermined light, or a predetermined combination of sound and light.