WO2022202670A1 - 発光素子駆動装置、発光装置、および車両 - Google Patents
発光素子駆動装置、発光装置、および車両 Download PDFInfo
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- WO2022202670A1 WO2022202670A1 PCT/JP2022/012646 JP2022012646W WO2022202670A1 WO 2022202670 A1 WO2022202670 A1 WO 2022202670A1 JP 2022012646 W JP2022012646 W JP 2022012646W WO 2022202670 A1 WO2022202670 A1 WO 2022202670A1
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/30—Driver circuits
- H05B45/345—Current stabilisation; Maintaining constant current
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/10—Controlling the intensity of the light
- H05B45/18—Controlling the intensity of the light using temperature feedback
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/30—Driver circuits
- H05B45/32—Pulse-control circuits
- H05B45/325—Pulse-width modulation [PWM]
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
- H05B47/20—Responsive to malfunctions or to light source life; for protection
- H05B47/28—Circuit arrangements for protecting against abnormal temperature
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60Q—ARRANGEMENT OF SIGNALLING OR LIGHTING DEVICES, THE MOUNTING OR SUPPORTING THEREOF OR CIRCUITS THEREFOR, FOR VEHICLES IN GENERAL
- B60Q1/00—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor
- B60Q1/02—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to illuminate the way ahead or to illuminate other areas of way or environments
- B60Q1/04—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to illuminate the way ahead or to illuminate other areas of way or environments the devices being headlights
- B60Q1/14—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to illuminate the way ahead or to illuminate other areas of way or environments the devices being headlights having dimming means
- B60Q1/1415—Dimming circuits
Definitions
- the present disclosure relates to a light-emitting element driving device.
- LEDs light emitting diodes
- a conventional LED driving device is disclosed in Patent Document 1, for example.
- the LED driving device of Patent Document 1 has a current setting section. An output current supplied to the LED is generated according to the reference current generated by the current setting unit.
- the current setting unit is connected to a setting resistor and a negative characteristic thermistor that are externally attached to the LED driving device.
- the current setting resistor and the negative characteristic thermistor are connected in parallel.
- the current setting characteristic realized by the current setting unit is a positive characteristic (characteristic in which the reference current increases as the resistance value of the current setting resistor increases).
- the light-emitting element driving device of Patent Document 2 includes a current driver that generates an output current flowing through a light-emitting element light source connected between a power supply voltage application terminal and a ground terminal, and the light-emitting element light source that is driven when the power supply voltage drops. and a bypass function unit that bypasses at least one of the plurality of constituent light emitting elements to reduce the number of series stages of the light emitting elements through which the output current flows. As a result, lighting of the light emitting element light source can be maintained even when the power supply voltage drops.
- LEDs have the characteristic that the luminance drops significantly as the ambient temperature of the LEDs rises.
- the output current is reduced as the temperature rises, so there is room for improvement in terms of LED brightness control.
- the first object of the present disclosure is to provide a light-emitting element driving device capable of suppressing changes in luminance of light-emitting elements due to temperature changes.
- the first object of the present disclosure is to provide a light-emitting element driving device having a bypass function that realizes suppression of abnormal lighting of the light-emitting element due to the occurrence of an open circuit by an effective configuration. 2 purpose.
- a light-emitting element driving device includes: a first external terminal connectable to the first setting resistor; a second external terminal connectable to a negative characteristic first thermistor arranged around the light emitting element light source; a current setting unit that generates a set current based on the resistance value of the first set resistor; a current addition unit that generates an additional current having a negative characteristic with respect to the resistance value of the first thermistor; a current driver that generates an output current flowing through the light emitting element light source connected between a power supply voltage application terminal and a ground terminal based on a reference current that is the sum of the set current and the additional current; It is configured to have
- a light-emitting element driving device includes: a current driver for generating an output current flowing through a light emitting element light source connected between a power supply voltage application terminal and a ground terminal; a first external terminal connectable to a node where the high potential side light source and the low potential side light source included in the light emitting element light source are connected in series; a bypass control unit configured to draw the output current from the first external terminal according to the power supply voltage and control the conduction state of a path bypassing the low-potential-side light source; a constant current source and a switch provided between the power supply voltage application terminal and the first external terminal; a comparator that compares the voltage of the first external terminal and an open detection threshold voltage and outputs a detection signal; a UVLO unit that compares the power supply voltage with a UVLO (Under Voltage Lock Out) threshold voltage and outputs a UVLO detection signal; a variable setting unit that variably sets the open detection threshold voltage and the UVLO threshold voltage in conjunction with
- the light-emitting element driving device it is possible to suppress changes in brightness of the light-emitting elements due to temperature changes.
- the light-emitting element driving device in the light-emitting element driving device having the bypass function, it is possible to suppress abnormal lighting of the light-emitting element due to the occurrence of an open circuit with an effective configuration.
- FIG. 1 is a diagram showing the overall configuration of an LED light emitting device according to an exemplary embodiment.
- FIG. 2 is a diagram showing a specific internal configuration example of each of the current setting section and the current adding section.
- FIG. 3 is a graph showing an example of the relationship between the LED ambient temperature and luminance for a red LED.
- FIG. 4 is a graph showing an example of the relationship between the ambient temperature of the LED light source and the combined resistance value of the set resistor Rset_th and the thermistor TH1.
- FIG. 5 is a graph showing an example of the relationship between the ambient temperature of the LED light source and the additional current Iadd corresponding to FIG.
- FIG. 6 is a graph showing an example of the relationship between the ambient temperature of the LED light source and the reference current Iref corresponding to FIGS.
- FIG. 7 is a plan view showing an example of a socket-type LED module.
- FIG. 8 is an external view (front) showing an example of a vehicle in which the LED driving device is mounted.
- FIG. 9 is an external view (rear view) showing an example of a vehicle in which the LED driving device is mounted.
- FIG. 10 is a diagram showing the overall configuration of an LED light emitting device according to an exemplary embodiment;
- FIG. 11 is a diagram showing an internal configuration example of the CR timer.
- FIG. 12 is a diagram showing a case where no open occurs on the lower potential side than the node Nx.
- FIG. 13 is a diagram showing a case where an open occurs on the lower potential side than the node Nx.
- FIG. 12 is a diagram showing a case where no open occurs on the lower potential side than the node Nx.
- FIG. 14 shows the operation when no open occurs on the lower potential side than the node Nx.
- FIG. 15 is a diagram showing the operation when an open occurs on the lower potential side than the node Nx.
- FIG. 16 is a diagram showing the first output current and the second output current.
- FIG. 17 is a diagram showing a first configuration example of the variable setting section.
- FIG. 18 is a diagram showing a second configuration example of the variable setting section.
- FIG. 19 is a plan view showing a configuration example of a socket-type LED module.
- FIG. 20 is an enlarged view of a wiring pattern example on a substrate.
- FIG. 21 is an enlarged view of another example of the wiring pattern on the substrate.
- FIG. 22 is an external view (front) showing an example of a vehicle in which the LED driving device is mounted.
- FIG. 23 is an external view (rear view) showing an example of a vehicle in which the LED driving device is mounted.
- FIG. 1 is a diagram showing the overall configuration of an LED light emitting device X1 according to an exemplary embodiment.
- the LED light-emitting device X1 is an in-vehicle lamp that receives supply of the power supply voltage Vin from the battery B and lights. Examples of the LED light emitting device X1 include headlamps, daytime running lamps, tail lamps, stop lamps, turn lamps, and the like.
- the battery is a power source for the vehicle in which the LED light emitting device X1 is mounted, and a lead-acid battery, a lithium ion battery, or the like is preferably used.
- the LED light-emitting device X1 includes an LED driving device 5 and an LED light source 10, as well as various discrete components externally attached to the LED driving device 5, including setting resistors Rset, Rset_th, and thermistors TH1 and TH2.
- the LED driving device 5 is a semiconductor integrated circuit device (a so-called LED driver IC) that operates by receiving power supply voltage Vin from the battery B and generates an output current Iout to be supplied to the LED light source 10 .
- a semiconductor integrated circuit device a so-called LED driver IC
- the LED driving device 5 has a VIN terminal, an OUT terminal, a THD terminal, a SET terminal, a SET_TH terminal, and a GND terminal as external terminals for establishing electrical connection with the outside.
- the VIN terminal is connected to the application end of the power supply voltage Vin. That is, the LED driving device 5 is supplied with the power supply voltage Vin through the VIN terminal.
- the LED light source 10 is an LED string composed of a plurality of LED chips (light emitting elements) connected in series.
- the LED light source 10 may be composed of a single LED, or may be composed of LED chips connected in series and parallel.
- the LED driving device 5 has, as an internal configuration, a current driver 1, a current setting section 2, a current adding section 3, and a constant current source 4, which are integrated.
- the LED driving device 5 includes, in addition to the configuration shown in FIG. ) It has a light control unit that performs dimming, various abnormality detection units, an abnormality notification unit that notifies the abnormality to the outside, an internal power supply circuit that generates internal voltage, and a UVLO (Under Voltage Lock Out) unit.
- the current driver 1 is provided between the VIN terminal and the OUT terminal.
- the anode of the LED light source 10 is connected to the OUT terminal.
- the cathode of the LED light source 10 is connected to ground.
- the current driver 1 generates an output current Iout flowing through the LED light source 10 connected between the application terminal of the power supply voltage Vin and the ground terminal.
- the current driver 1 performs constant current control of the output current Iout so that the output current Iout matches a predetermined target value.
- the current driver 1 includes, for example, an output transistor provided on a current path through which the output current Iout flows, a sense resistor for converting the output current Iout into a feedback voltage, a feedback voltage and a reference voltage. and an error amplifier that linearly drives the output transistor so that Note that the target value of the output current Iout can be arbitrarily set according to the reference current Iref, which will be described later.
- the current setting unit 2 generates a set current Iset.
- the set current Iset is used to generate the reference current Iref. That is, the current setting unit 2 generates the set current Iset for setting the target value of the output current Iout.
- the setting current Iset can be adjusted by adjusting the resistance value of the setting resistor Rset externally connected to the SET terminal.
- a constant current source 4 is provided between the terminal for applying the internal voltage Vreg and the THD terminal.
- a thermistor TH2 is externally connected to the THD terminal.
- the thermistor TH2 is a negative characteristic thermistor.
- a negative temperature coefficient thermistor has a characteristic that the higher the temperature, the smaller the resistance value.
- the thermistor TH2 is arranged around the LED light source 10 .
- the constant current source 4 supplies a constant current Ithd to the thermistor TH2 via the THD terminal, thereby generating a terminal voltage Vthd at the THD terminal.
- the current setting unit 2 adjusts the set current Iset based on the terminal voltage Vthd. Thereby, temperature derating is performed to adjust the output current Iout according to the ambient temperature of the LED light source 10 .
- the current addition unit 3 generates an additional current Iadd.
- the reference current Iref is generated by synthesizing (summing) the set current Iset and the additional current Iadd.
- a setting resistor Rset_th and a thermistor TH1 are connected in series between the SET_TH terminal and the ground terminal.
- the thermistor TH ⁇ b>1 is a negative characteristic thermistor and is arranged around the LED light source 10 .
- the current adder 3 adjusts the additional current Iadd based on the resistance value of the setting resistor Rset_th and the resistance value of the thermistor TH1 (that is, the combined resistance value of the setting resistor Rset_th and the thermistor TH1) and the terminal voltage Vthd. Therefore, the current addition unit 3 adjusts the output current Iout according to the ambient temperature of the LED light source 10 to perform brightness control and temperature derating of the LED light source 10 .
- FIG. 2 is a diagram showing a specific internal configuration example of each of the current setting section 2 and the current adding section 3. As shown in FIG.
- the current setting unit 2 has an output transistor 2A and an error amplifier 2B.
- the output transistor 2A is arranged on the path through which the set current Iset flows, and is composed of an NMOS transistor (N-channel MOSFET).
- the source of the output transistor 2A is connected to the SET terminal.
- the node where the output transistor 2A and the SET terminal are connected is connected to the inverting input terminal (-) of the error amplifier 2B.
- a non-inverting input terminal (+) of the error amplifier 2B is connected to the THD terminal.
- the output terminal of the error amplifier 2B is connected to the gate of the output transistor 2A.
- the current addition unit 3 has an output transistor 3A and an error amplifier 3B.
- the output transistor 3A is arranged in the path through which the additional current Iadd flows, and is composed of an NMOS transistor.
- the drain of the output transistor 3A is connected to the drain of the output transistor 2A.
- the source of the output transistor 3A is connected to the SET_TH terminal.
- a node where the output transistor 3A and the SET_TH terminal are connected is connected to the inverting input terminal (-) of the error amplifier 3B.
- a non-inverting input terminal (+) of the error amplifier 3B is connected to the THD terminal.
- the output terminal of the error amplifier 3B is connected to the gate of the output transistor 3A.
- the voltage of the SET terminal is controlled so as to match the terminal voltage Vthd, so the set current Iset is represented by the following equation.
- Iset Vthd/Rset
- Vthd TH2 x Itd (TH2: resistance value of thermistor TH2)
- the set current Iset has a negative characteristic with respect to the set resistor Rset (the characteristic that the set current Iset decreases as the resistance value of the set resistor Rset increases), and the set current Iset decreases with respect to the thermistor TH2 (terminal voltage Vthd). has a positive characteristic (characteristic that the set current Iset increases as the resistance value of the thermistor TH2 increases (as the terminal voltage Vthd increases)).
- the additional current Iadd has a negative characteristic with respect to the resistance value of the thermistor TH1 (a characteristic in which the additional current Iadd decreases as the resistance value of the thermistor TH1 increases), and with respect to the thermistor TH2 (terminal voltage Vthd). has a positive characteristic (characteristic that the additional current Iadd increases as the resistance value of the thermistor TH2 increases (as the terminal voltage Vthd increases)).
- the target value of the output current Iout is set larger as the reference current Iref is larger (positive characteristic with respect to the reference current Iref).
- the additional current Iadd increases.
- the additional current Iadd decreases. The additional current Iadd increases as the temperature rises.
- FIG. 3 shows an example of the relationship between the LED ambient temperature (horizontal axis) and luminance (vertical axis) in the case of a red LED (assuming that the LED current is a predetermined constant value).
- the luminance on the vertical axis is indicated by the ratio of the luminance to the luminance at 20°C.
- Characteristics differ depending on the LED used, and two examples of characteristics are shown in FIG. 3 with a solid line and a dashed line. In this way, LEDs have the characteristic that the brightness drops significantly as the temperature rises. Therefore, by increasing the additional current Iadd as the ambient temperature of the LED light source 10 rises as described above, the reference current Iref and, in turn, the output current Iout can be increased to suppress the decrease in brightness.
- FIG. 4 shows an example of the relationship between the ambient temperature of the LED light source 10 (LED ambient temperature) and the combined resistance value of the set resistor Rset_th and the thermistor TH1.
- LED ambient temperature the ambient temperature
- Rset_th the combined resistance value of the set resistor
- thermistor TH1 the combined resistance value of the set resistor Rset_th and the thermistor TH1.
- FIG. 5 shows an example of the relationship between the LED ambient temperature and the additional current Iadd corresponding to FIG.
- the additional current Iadd increases as the temperature rises at low temperatures, but at high temperatures the change in the combined resistance value is suppressed as shown in FIG. increases, and the additional current Iadd decreases as the temperature increases.
- the reference current Iref and, in turn, the output current Iout can be decreased at high temperatures as the temperature rises, and the heat generation of the LED light source 10 can be suppressed. Therefore, the life of the LED light source 10 can be extended.
- FIG. 6 shows an example of the relationship between the LED ambient temperature and the reference current Iref corresponding to FIGS.
- the higher the ambient temperature of the LED the smaller the resistance value of the thermistor TH2 and the smaller the set current Iset. Since the increasing change in the additional current Iadd with the increase in LED temperature is greater than the decreasing change in the set current Iset, the reference current Iref increases. However, when the ambient temperature around the LED is high, the additional current Iadd decreases as the temperature rises, as shown in FIG. As a result, the output current Iout can be reduced where the LED ambient temperature is high, and the heat generation of the LED light source 10 can be suppressed.
- the non-inverting input terminal (+) of the error amplifier 3B in the current adding section 3 is not limited to the connection of the THD terminal, and may be connected to, for example, the application terminal of the internal voltage of a fixed value.
- the additional current Iadd does not decrease when the LED ambient temperature is high, but the increase in the additional current Iadd is suppressed by using the setting resistor Rset_th.
- FIG. 7 is a plan view showing a socket-type LED module Y as an example of realizing the LED light-emitting device X1 described so far.
- the socket-type LED module Y of this configuration example is, for example, a vehicle-mounted lighting fixture, and includes a substrate 300 , an LED chip 400 , a white resin 480 , a reflector 600 , an LED driving device 5 , and a socket 900 .
- the LED chip 400 shown in FIG. 7 shows the case where the number of LED chips constituting the LED light source 10 corresponding to the example of FIG. 1 is three, the number of LED chips is not limited to this. Further, in FIG. 7, the illustration of electronic components externally attached to the LED drive device 5 is omitted for the sake of convenience.
- the substrate 300 has a base material and a wiring pattern formed thereon (see the hatched area in this figure).
- the base material has a rectangular shape and is made of glass epoxy resin, for example.
- the wiring pattern is a conductive member laid on the surface of the substrate for mounting the LED chip 400 and various electronic components, and is made of metal such as Cu or Ag, for example.
- the LED driving device 5 and various external components are mounted on the upper surface of the substrate 300 .
- Each electronic component is connected by wiring patterns laid on the upper and lower surfaces of the substrate 300 to form a circuit, and is for lighting the LED chip 400 in a desired light emission state.
- the reflector 600 is made of, for example, white resin, and is fixed to the central region of the substrate 300 so as to surround the LED chip 400 .
- the reflector 600 serves to reflect upward the light emitted sideways from the LED chip 400 .
- a reflecting surface 601 is formed on the reflector 600 .
- a reflective surface 601 surrounds the LED chip 400 .
- the reflective surface 601 moves away from the LED chip 400 in the direction perpendicular to the thickness direction of the substrate 300 as the distance from the substrate 300 increases in the thickness direction of the substrate 300 .
- the reflective surface 601 has a tapered shape in which the cross section orthogonal to the thickness direction of the substrate 300 becomes larger toward the opening side of the reflector 600 .
- the white resin 480 is made of a white resin material that does not transmit light from the LED chip 400, and corresponds to an example of an opaque resin. As understood from FIG. 7 , the white resin 480 surrounds the LED chip 400 and its outer edge reaches the reflective surface 601 of the reflector 600 . Therefore, in FIG. 7, white resin 480 fills the area extending from LED chip 400 to reflecting surface 601 in the vertical and horizontal directions in the figure.
- the socket 900 is a component for mounting the substrate 300 and attaching it to, for example, an automobile.
- the socket 900 is made of synthetic resin, for example, and is formed by injection molding, for example.
- the socket 900 has a mounting portion 910 for mounting the substrate 300 and a mounting portion for mounting on an automobile or the like.
- the mounting portion 910 has a cylindrical shape with one opening, and the substrate 300 is mounted on the inner bottom surface of the mounting portion 910 .
- a radiator plate 950 which is a circular plate made of aluminum, for example, is fixed to the inner bottom surface of the mounting portion 910 .
- the substrate 300 is mounted on the mounting portion 910 of the socket 900 by bonding the lower surface to the upper surface of the heat sink 950 with an adhesive.
- the white resin 480 covers the entire annular area from the supporting substrate of the LED chip 400 to the reflecting surface 601 of the reflector 600. Therefore, the area surrounded by the reflective surface 601 is covered with the white resin 480 except for the area occupied by the LED chip 400 . This makes it possible to reflect more light from the semiconductor layer of the LED chip 400 . This is suitable for increasing the brightness of the socket-type LED module Y. In addition, it is not necessary to perform a separate process for appropriately reflecting light on the area surrounded by the reflecting surface 601 of the substrate 300 .
- the reflector 600 having the reflective surface 601 By providing the reflector 600 having the reflective surface 601, the direction directly above the socket-type LED module Y can be illuminated more brightly.
- the LED chip 400 (LED light source 10) is provided in such a socket-type LED module Y
- the ambient temperature around the LED light source 10 tends to rise. Therefore, the effect of suppressing the decrease in luminance due to the increase in the ambient temperature of the LED by controlling the luminance as in the LED driving device 5 of the present embodiment is important. Furthermore, the effect of suppressing heat generation of the LED light source 10 by performing temperature derating to reduce the output current Iout at a high LED ambient temperature as in the LED driving device 5 of the present embodiment is important.
- the LED driving device 5 described so far includes, for example, headlamps (including high beam/low beam/small lamp/fog lamp, etc.) X11 of vehicle X10, daytime running lamps ( DRL [daylight running lamps]) X12, tail lamps (including small lamps or back lamps as appropriate) X13, stop lamps X14, turn lamps X15, and the like.
- the LED driving device 5 may be provided as a module (such as the aforementioned socket-type LED module Y) together with the LED light source 10 to be driven, or may be provided as a single IC independently of the LED light source 10. It may be provided as a module (such as the aforementioned socket-type LED module Y) together with the LED light source 10 to be driven, or may be provided as a single IC independently of the LED light source 10. It may be provided as a module (such as the aforementioned socket-type LED module Y) together with the LED light source 10 to be driven, or may be provided as a single IC independently of the LED light source 10. It may be provided as a module (such as the aforementioned socket-type LED module Y) together with the LED light source 10 to be driven, or may be provided as a single IC independently of the LED light source 10. It may be provided as a module (such as the aforementioned socket-type LED module Y) together with the LED light source 10 to be driven, or may be provided as a single IC independently of
- the configuration using an LED as a light emitting element was described as an example, but the configuration of the present invention is not limited to this, and the brightness decreases as the temperature rises.
- the light-emitting element driving device (5) is a first external terminal (SET terminal) connectable to the first setting resistor (Rset); a second external terminal (SET_TH terminal) connectable to a negative characteristic first thermistor (TH1) arranged around the light emitting element light source (10); a current setting unit (2) that generates a set current (Iset) based on the resistance value of the first set resistor; a current adding section (3) for generating an additional current (Iadd) having a negative characteristic with respect to the resistance value of the first thermistor; Based on the reference current (Iref) which is the sum of the set current and the additional current, the output current (Iout) flowing through the light emitting element light source connected between the application terminal of the power supply voltage (Vin) and the ground terminal is determined.
- a second setting resistor (Rset_th) connected in series with the first thermistor (TH1) can be connected to the second external terminal (SET_TH terminal), and the current addition
- the unit may be configured to generate the additional current having a negative characteristic with respect to the combined resistance value of the first thermistor and the second set resistor (second configuration).
- a third external terminal connectable to a second thermistor (TH2) having a negative characteristic disposed around the light emitting element light source, and a terminal connected to the third external terminal and a constant current source (4), wherein the current addition unit generates the additional current having a positive characteristic with respect to the terminal voltage (Vthd) of the third external terminal (the third configuration).
- the current setting section may be configured to generate the set current having a positive characteristic with respect to the terminal voltage (fourth configuration).
- the current setting unit includes a first output transistor (2A) arranged on a path through which the set current flows, a first terminal of the first output transistor and the first external terminal (SET terminal), a second input terminal connected to the application terminal of the terminal voltage (Vthd), and a control terminal of the first output transistor. and a first error amplifier (2B) including an output terminal (fifth configuration).
- the current adding section includes a second output transistor (3A) arranged on a path through which the additional current flows, and a first end of the second output transistor. a first input terminal connected to a second node connected to the second external terminal (SET_TH terminal), a second input terminal connected to a reference voltage (Vthd) application terminal, and the second output transistor and a second error amplifier (3B) including a second error amplifier (3B) (sixth configuration).
- a third external terminal connectable to a negative characteristic second thermistor (TH2) arranged around the light emitting element light source, and a terminal connected to the third external terminal a constant current source (4), wherein a second setting resistor (Rset_th) connected in series with the first thermistor is connectable to the second external terminal (SET_TH terminal);
- the reference voltage may be the terminal voltage (Vthd) of the third external terminal (seventh configuration).
- the light-emitting device (X1) includes a light-emitting element driving device (5) having any one of the first to seventh configurations and the light-emitting element light source (10) ( eighth configuration).
- the light emitting element light source may be an LED light source (ninth configuration).
- vehicle (X10) is configured to have the light emitting device having any one of the eighth to tenth configurations.
- FIG. 10 is a diagram showing the overall configuration of an LED light emitting device X1 according to an exemplary embodiment.
- the LED light-emitting device X1 is an in-vehicle lamp that lights when supplied with a power supply voltage Vin from a battery (not shown). Examples of the LED light emitting device X1 include headlamps, daytime running lamps, tail lamps, stop lamps, turn lamps, and the like.
- the battery is a power source for the vehicle in which the LED light emitting device X1 is mounted, and a lead-acid battery, a lithium ion battery, or the like is preferably used.
- the LED light emitting device X1 includes an LED driving device 15 and an LED light source 200.
- the LED driving device 15 is a semiconductor integrated circuit device (a so-called LED driver IC) that operates by receiving supply of the power supply voltage Vin from the battery and generates an output current Iout to be supplied to the LED light source 200 .
- the LED driving device 15 has a VIN terminal, an OUT terminal, an ISINK terminal, a CRT terminal, a DISC terminal, and a CNT terminal as external terminals for establishing electrical connection with the outside.
- the VIN terminal is connected to the application end of the power supply voltage Vin. That is, the LED driving device 15 receives supply of the power supply voltage Vin via the VIN terminal.
- the LED light source 200 is an LED string composed of a plurality of LED chips (light emitting elements) connected in series.
- the LED light source 200 is divided into a high potential side LED 201 (high potential side light source) and a low potential side LED 202 (low potential side light source).
- the low potential side LED 202 is composed of at least one LED chip. In the example shown in FIG. 10, the low potential side LED 202 consists of two LED chips connected in series. The cathode of the low potential side LED 202 is connected to the ground terminal. On the other hand, the node Nx where the cathode of the high potential side LED 201 and the anode of the low potential side LED 202 are connected is connected to the ISINK terminal, the reason for which will be described later.
- the LED driving device 15 has an internal configuration including a current driver 1, a UVLO section 2, a control logic section 3, a bypass control section 4, a constant current circuit 5, a comparator 6, a constant current source 7, and a switch 8. , a CR timer 9 and a variable setting unit 10 are integrated.
- the LED driving device 15 includes, in addition to the configuration shown in FIG. and an output current setting unit for setting the output current Iout.
- the abnormality detection unit includes an LED open detection unit that detects open of the LED light source 200 based on the voltage of the OUT terminal, an output ground fault detection unit that detects a ground fault of the OUT terminal based on the voltage of the OUT terminal, a temperature protection circuit ( TSD), etc.
- the current driver 1 performs constant current control of the output current Iout so that the output current Iout flowing through the LED light source 200 matches a predetermined target value.
- the current driver 1 has an error amplifier 1A, a sense resistor 1B and a PMOS transistor 1C.
- One end of the sense resistor 1B is connected to the application end of the power supply voltage Vin.
- the other end of the sense resistor 1B is connected to the inverting input terminal (-) of the error amplifier 1A and to the source of the PMOS transistor 1C.
- the non-inverting input terminal (+) of the error amplifier 1A is connected to the application terminal of the reference voltage.
- the output terminal of the error amplifier 1A is connected to the gate of the PMOS transistor 1C.
- the drain of the PMOS transistor 1C is connected to the OUT terminal.
- a UVLO (Under Voltage Lock Out) unit 2 is a circuit that detects a voltage drop in the power supply voltage Vin.
- the UVLO unit 2 compares the power supply voltage Vin and the UVLO threshold voltage Vin_UVLO, and outputs a UVLO detection signal Suvlo as a comparison result.
- the control logic unit 3 is the main body that controls the overall operation of the LED driving device 15 .
- the control logic unit 3 performs stop control of the output current Iout according to the detection results obtained by various abnormality detection units (LED open detection unit, output ground fault detection unit, temperature protection circuit, etc.), or
- the notification unit is caused to perform notification to the outside.
- FIG. 11 is a diagram showing an internal configuration example of the CR timer 9. As shown in FIG. The CR timer 9 is configured to enable PWM dimming by connecting external components (capacitor Ccrt, resistor Rcrt) to the CRT terminal and the DISC terminal.
- external components capacitor Ccrt, resistor Rcrt
- the CRT timer 9 has a constant current source 9A, a switch 9B, a comparator 9C, a comparator 9D, a NOR circuit 9E, an NMOS transistor 9F, and an NMOS transistor 9G.
- One end of a capacitor Ccrt is externally connected to the CRT terminal.
- One end of a resistor Rcrt is also connected to the CRT terminal.
- the other end of the resistor Rcrt is connected to the DISC terminal.
- the comparator 9C compares the voltage of the CRT terminal with the reference voltage Vcrt_dis1.
- a constant current source 9A and a switch 9B are provided between the terminal to which the internal voltage Vreg is applied and the CRT terminal.
- the internal voltage Vreg is generated by an internal voltage source (not shown) based on the power supply voltage Vin.
- the switch 9B is turned on and off according to the output of the comparator 9C.
- the comparator 9D compares the voltage of the CRT terminal and the reference voltage Vcrt_dis2 (>Vcrt_dis1).
- One input terminal of the NOR circuit 9E is connected to the output terminal of the comparator 9C.
- the other input terminal of the NOR circuit 9E is connected to the output terminal of the comparator 9D.
- the drain of the NMOS transistor 9F is connected to the DISC terminal.
- the source of NMOS transistor 9F is connected to the ground terminal.
- the gate of NMOS transistor 9F is connected to the output terminal of NOR circuit 9E.
- the drain of the NMOS transistor 9G is connected to the DISC terminal.
- the source of NMOS transistor 9G is connected to the ground terminal.
- the gate of NMOS transistor 9G is connected to the output terminal of comparator 9D.
- a switch SWdc is arranged between the battery B that generates the power supply voltage Vin and the CRT terminal.
- the switch SWdc is turned off. In this case, a triangular wave is generated at the CRT terminal.
- the PWM dimming signal Spwm output from the comparator 9C is generated in a pulse shape.
- the control logic unit 3 generates an LED-on signal Sled_on based on the PWM dimming signal Spwm, and controls the current driver 1 on and off.
- the current driver 1 that is, the output current Iout
- the current driver 1 that is, the output current Iout
- the frequency and on-duty of PWM dimming can be arbitrarily set by adjusting the resistance value of resistor Rcrt and the capacitance value of capacitor Ccrt.
- the switch SWdc when used in the DC dimming mode, the switch SWdc is turned on to apply the power supply voltage Vin to the CRT terminal.
- the PWM dimming signal Spwm is fixed at Low level and the current driver 1 is kept on.
- the output of the comparator 9D is set to High level, and the NMOS transistor 9F is turned off and the NMOS transistor 9G is turned on. state can be switched. Since the NMOS transistor 9G has a higher on-resistance than the NMOS transistor 9F, the power consumption of the IC can be suppressed by reducing the inflow current to the DISC terminal.
- the bypass control unit 4 and the constant current circuit 5 constitute a bypass function unit.
- the constant current circuit 5 has an error amplifier 5A, an NMOS transistor 5B, and a sense resistor 5C.
- the drain of the NMOS transistor 5B is connected to the ISINK terminal.
- the source of NMOS transistor 5B is connected to one end of sense resistor 5C.
- the other end of the sense resistor 5C is connected to the ground terminal.
- a node where the NMOS transistor 5B and the sense resistor 5C are connected is connected to the inverting input terminal (-) of the error amplifier 5A.
- a reference voltage application terminal is connected to the non-inverting input terminal (+) of the error amplifier 5A.
- the bypass control unit 4 performs on/off control of the constant current circuit 5 .
- the constant current circuit 5 When the constant current circuit 5 is in the ON state, the output current Iout flows through the high potential side LED 201 and is drawn into the constant current circuit 5 from the ISINK terminal. That is, the low potential side LED 202 is bypassed.
- the low-potential-side LED 202 is bypassed to reduce the number of series stages of the LED chips through which the output current Iout flows. 200 lighting can be maintained.
- the output current Iout flows through the high potential side LED 201 and the low potential side LED 202 in order, and all the LED chips in the LED light source 200 are lit. do.
- Open detection function> When the power supply voltage Vin rises (at the start of the power supply voltage Vin), the constant current circuit 5 is turned on during a period when the power supply voltage Vin is low, thereby bypassing the low potential side LED 202 and lighting the high potential side LED 201, After that, when the power supply voltage Vin increases, control is performed to switch the constant current circuit 5 to the off state. However, if an open occurs on the low potential side of the node Nx (including an open at the low potential side LED 202), and the constant current circuit 5 is in the off state, the output current Iout will not flow. lights out. In such a case, when seen by human eyes, the LED light source 200 turns on momentarily and then turns off. Therefore, the LED driving device 15 according to the present embodiment is provided with a function (open detection function) for detecting the occurrence of an open on the lower potential side than the node Nx.
- a function open detection function
- the comparator 6 is provided for the open detection function as described above.
- a non-inverting input terminal (+) of the comparator 6 is connected to the ISINK terminal.
- the inverting input terminal (-) of the comparator 6 is connected to the application terminal of the open detection threshold voltage Vth_op.
- the comparator 6 compares the voltage of the ISINK terminal and the open detection threshold voltage Vth_op, and outputs a detection signal Sdet as a comparison result to the bypass control section 4 .
- a constant current source 7 and a switch 8 are also provided for the open detection function.
- a constant current source 7 and a switch 8 are provided between the terminal for applying the power supply voltage Vin and the ISINK terminal.
- the bypass controller 4 keeps the constant current circuit 5 in an off state.
- the UVLO signal Suvlo indicating UVLO cancellation is output from the UVLO unit 2 .
- the bypass control unit 4 switches the switch 8 to the on state when the UVLO signal Suvlo indicates UVLO cancellation and the LED-on signal Sled_on indicates on.
- the low potential side LED 202 is driven by the constant current Imoni (broken line arrow) via the switch 8 and the ISINK terminal which are turned on. ) flows.
- the open detection threshold voltage Vth_op is set to a voltage higher than the voltage of the ISINK terminal.
- the comparator 6 determines that the voltage of the ISINK terminal is lower than the open detection threshold voltage Vth_op, and outputs a low-level detection signal Sdet indicating that no open has occurred.
- the bypass control unit 4 switches the constant current circuit 5 to the ON state.
- the low potential side LED 202 is bypassed, the output current Iout is drawn from the high potential side LED 201 to the ISINK terminal, and the high potential side LED lights up.
- the bypass control unit 4 switches the constant current circuit 5 to the OFF state, thereby canceling the bypass, and the output current Iout flows through the high potential side LED 201 and the low potential side LED 202, and the LED light source 200 all the LED chips in the light up.
- the capacitive element Csink is an EMC (Electromagnetic Compatibility) test countermeasure element externally connected to the ISINK terminal.
- the EMC test is a BCI (Bulk Current Injection) test that injects noise into the power supply line, and the capacitive element Csink is provided to suppress fluctuations in the voltage of the ISINK terminal during the test.
- a comparator 6 compares the voltage of the ISINK terminal generated by the charging and the open detection threshold voltage Vth_op. Since the voltage of the ISINK terminal becomes higher than the open detection threshold voltage Vth_op, the comparator 6 outputs a high-level detection signal Sdet indicating the occurrence of an open.
- the open detection threshold voltage Vth_op must be less than or equal to the UVLO threshold voltage Vin_UVLO.
- the level of the PWM dimming signal Spwm output from the CR timer 9 is fixed, and the LED-on signal Sled_on indicates ON when the UVLO is canceled.
- the voltage of the ISINK terminal does not exceed the power supply voltage Vin. Therefore, if the open detection threshold voltage Vth_op is higher than the UVLO threshold voltage Vin_UVLO, the voltage of the ISINK terminal is lower than the open detection threshold voltage Vth_op, and the comparator This is because there is a risk of erroneous detection if an open does not occur according to 6.
- the bypass control unit 4 determines whether the ISINK terminal is open based on the detection signal Sdet that is output from the comparator 6, and the voltage at the ISINK terminal increases from the open detection threshold voltage Vth_op due to charging. must wait for the waiting time required for the The required waiting time Twait must satisfy the condition of the following formula (1).
- C Cled+Csink
- bypass control unit 4 After the bypass control unit 4 waits for the waiting time Twait, it determines whether it is open. As a result, momentary lighting of the high-potential-side LED 201 due to the occurrence of an open can be avoided.
- the operation when the power supply voltage Vin is started will be described.
- the waveforms of the power supply voltage Vin, the constant current Imoni, the voltage Vsink of the ISINK terminal, the output current Iout, the first output current Ia, and the second output current Ib are shown in order from the top.
- the first output current Ia is the output current flowing through the path from the node Nx to the ISINK terminal
- the second output current Ib is the path from the node Nx to the low potential side LED 202.
- the open detection threshold voltage Vth_op is equal to or lower than the UVLO threshold voltage Vin_UVLO.
- FIG. 14 is a diagram showing the operation when no open occurs on the lower potential side than the node Nx. Note that FIG. 14 and FIG. 15 described later show the case of the DC dimming mode.
- FIG. 15 shows the operation when an open occurs on the lower potential side than the node Nx.
- the power supply voltage Vin rises from 0V and becomes equal to or higher than the UVLO threshold voltage Vin_UVLO (timing t11)
- Vin_UVLO threshold voltage
- the UVLO is released and the LED-on signal Sled_on indicates on, so the switch 8 is turned on immediately. state can be switched.
- Vsink exceeds the open detection threshold voltage Vth_op.
- the bypass control unit 4 determines that an open state has occurred based on the detection signal Sdet, turns off the switch 8, and maintains the off state of the constant current circuit 5.
- the output current Iout does not flow, and the high-potential-side LED 201 does not light.
- variable setting section 10 Next, the variable setting section 10 will be described.
- the number of LED chips forming the low potential side LED 202 may change. For example, although the number is two in FIG. 1, it may be, for example, three. In this case, the total forward voltage of the low potential side LEDs 202 changes according to the change in the number.
- the open detection threshold voltage Vth_op needs to be set higher than the total forward voltage of the low potential side LED 202. Therefore, the open detection threshold voltage Vth_op is determined according to the number of LED chips forming the low potential side LED 202. It is necessary to change the threshold voltage Vth_op.
- the UVLO threshold voltage Vin_UVLO since the UVLO threshold voltage Vin_UVLO must be equal to or higher than the open detection threshold voltage Vth_op, it is necessary to change the open detection threshold voltage Vth_op in accordance with the change in the open detection threshold voltage Vth_op as described above. .
- the waiting time Twait it is necessary to change the waiting time Twait according to the change in the open detection threshold voltage Vth_op.
- the capacitive element Csink is not essential and may be omitted.
- the waiting time Twait may be a fixed value.
- variable setting unit 10 sets the open detection threshold voltage Vth_op, the UVLO threshold voltage Vin_UVLO, and the waiting time Twait in the bypass control unit 4 according to the number of LED chips that constitute the low potential side LED 202. It is supposed to be interlocked and variably set.
- the variable setting unit 10 performs variable setting using the CNT terminal.
- the variable setting unit 10 detects, for example, two patterns of open/GND (ground potential) application to the CNT terminal, and variably sets according to the detection result.
- variable setting unit 10 detects, for example, three patterns of application of the power supply voltage Vin/open/GND to the CNT terminal, and variably sets according to the detection result.
- FIG. 17 is a diagram showing a configuration example of the variable setting section 10 configured to detect the above three patterns.
- the variable setting section 10 has comparators 10A, 10B, 10C and a constant current source 10D.
- the non-inverting input terminal (+) of the comparator 10A is connected to the CNT terminal.
- the inverting input terminal (-) of the comparator 10A is connected to the application terminal of the reference voltage V1.
- the inverting input terminal (-) of the comparator 10B is connected to the CNT terminal.
- the non-inverting input terminal (+) of the comparator 10B is connected to the application terminal of the reference voltage V2.
- the inverting input terminal (-) of the comparator 10C is connected to the CNT terminal.
- the non-inverting input terminal (+) of the comparator 10C is connected to the application terminal of the reference voltage V3.
- a constant current source 10D is provided between the terminal to which the internal voltage Vdd is applied and the CNT terminal.
- the reference voltage V1 is set to a voltage value slightly higher than 0V (for example, 0.6V).
- the reference voltage V3 is set to a voltage slightly lower than the power supply voltage Vin (for example, VIN-1V).
- FIG. 18 is a diagram showing another configuration example of the variable setting unit 10. As shown in FIG. In the configuration shown in FIG. 18, the variable setting section 10 has a constant current source 10E.
- the constant current source 10E is provided between the application terminal of the internal voltage Vdd and the CNT terminal.
- a setting resistor Rcnt is externally connected to the CNT terminal.
- Icnt constant current value by the constant current source 10E.
- FIG. 19 is a plan view showing a socket-type LED module Y as an example of the LED light-emitting device X1 described above.
- the socket-type LED module Y of this configuration example is, for example, a vehicle-mounted lighting fixture, and includes a substrate 300 , an LED chip 400 , a white resin 480 , a reflector 600 , an LED driving device 15 , and a socket 900 .
- the LED chip 400 shown in FIG. 19 is shown as a case in which the number of LED chips constituting the LED light source 200 is three, but the number of LED chips is not limited to this (the number of LED chips in the example of FIG. number is 4).
- electronic components externally attached to the LED driving device 15 are omitted for convenience.
- the substrate 300 has a base material and a wiring pattern formed thereon (see the hatched area in this figure).
- the base material has a rectangular shape and is made of glass epoxy resin, for example.
- the wiring pattern is a conductive member laid on the surface of the substrate for mounting the LED chip 400 and various electronic components, and is made of metal such as Cu or Ag, for example.
- the LED driving device 15 and various external components are mounted on the upper surface of the substrate 300 .
- Each electronic component is connected by wiring patterns laid on the upper and lower surfaces of the substrate 300 to form a circuit, and is for lighting the LED chip 400 in a desired light emission state.
- the reflector 600 is made of, for example, white resin, and is fixed to the central region of the substrate 300 so as to surround the LED chip 400 .
- the reflector 600 serves to reflect upward the light emitted sideways from the LED chip 400 .
- a reflecting surface 601 is formed on the reflector 600 .
- a reflective surface 601 surrounds the LED chip 400 .
- the reflective surface 601 moves away from the LED chip 400 in the direction perpendicular to the thickness direction of the substrate 300 as the distance from the substrate 300 increases in the thickness direction of the substrate 300 .
- the reflective surface 601 has a tapered shape in which the cross section orthogonal to the thickness direction of the substrate 300 becomes larger toward the opening side of the reflector 600 .
- the white resin 480 is made of a white resin material that does not transmit light from the LED chip 400, and corresponds to an example of an opaque resin. As understood from FIG. 19 , the white resin 480 surrounds the LED chip 400 and its outer edge reaches the reflective surface 601 of the reflector 600 . For this reason, in FIG. 19, white resin 480 fills the area extending from LED chip 400 to reflective surface 601 in the vertical and horizontal directions in the figure.
- the socket 900 is a component for mounting the substrate 300 and attaching it to, for example, an automobile.
- the socket 900 is made of synthetic resin, for example, and is formed by injection molding, for example.
- the socket 900 has a mounting portion 910 for mounting the substrate 300 and a mounting portion for mounting on an automobile or the like.
- the mounting portion 910 has a cylindrical shape with one opening, and the substrate 300 is mounted on the inner bottom surface of the mounting portion 910 .
- a radiator plate 950 which is a circular plate made of aluminum, for example, is fixed to the inner bottom surface of the mounting portion 910 .
- the substrate 300 is mounted on the mounting portion 910 of the socket 900 by bonding the lower surface to the upper surface of the heat sink 950 with an adhesive.
- the white resin 480 covers the entire annular area from the supporting substrate of the LED chip 400 to the reflecting surface 601 of the reflector 600. Therefore, the area surrounded by the reflective surface 601 is covered with the white resin 480 except for the area occupied by the LED chip 400 . This makes it possible to reflect more light from the semiconductor layer of the LED chip 400 . This is suitable for increasing the brightness of the socket-type LED module Y. In addition, it is not necessary to perform a separate process for appropriately reflecting light on the area surrounded by the reflecting surface 601 of the substrate 300 .
- the reflector 600 having the reflective surface 601 By providing the reflector 600 having the reflective surface 601, the direction directly above the socket-type LED module Y can be illuminated more brightly.
- in-vehicle lamps are required to comply with regulations that must maintain the lighting state even when the power supply voltage Vin drops.
- the LED driving device 15 having a bypass function is very suitable as a driving main body for an in-vehicle lamp.
- FIG. 20 is an enlarged view of an example wiring pattern on the substrate 300.
- the wiring pattern shown in FIG. 20 includes a ground wiring 301 forming a so-called solid ground and a plurality of terminal wirings 302 arranged around the ground wiring 301 .
- the heat radiation pad 150 formed on the bottom surface of the LED driving device 15 is electrically connected to the ground wiring 301 .
- Each external terminal in the LED driving device 15 is electrically connected to each terminal wiring.
- a terminal wiring 302A shown in FIG. 20 is electrically connected to a CNT terminal of the LED driving device 15.
- FIG. 302 A of terminal wirings are integrated with the ground wiring 301, and it becomes possible to apply GND to a CNT terminal.
- FIG. 21 is an enlarged view of another example of the wiring pattern on the substrate 300.
- the wiring pattern shown in FIG. 21 includes terminal wiring 302B and terminal wiring 302C.
- Terminal wiring 302C is not a terminal wiring adjacent to terminal wiring 302B.
- Terminal wiring 302B is electrically connected to the CNT terminal of LED driving device 15 .
- the terminal wiring 302C is electrically connected to the VIN terminal of the LED driving device 15 .
- the terminal wiring 302B is connected to the terminal wiring 302C and the connection wiring 302D in order to apply the power supply voltage Vin to the CNT terminal.
- the connection wiring 302D extends in the horizontal direction along which the terminal wiring 302 (the external terminal of the LED driving device 15) is arranged.
- the substrate 300 is small in size, and there is a possibility that a component P (resistor, etc.) is arranged where the connection wiring 302D is to be provided, and the connection wiring 302D cannot be provided. In some cases. That is, there is a possibility that the power supply voltage Vin cannot be applied to the CNT terminal.
- the socket-type LED module Y it is easy to integrate the terminal wiring 302A for GND with the ground wiring 301 even if the size of the substrate 300 is small. Therefore, in the socket-type LED module Y, it is particularly easy to apply the LED driving device 15 provided with the variable setting section 10 configured to detect the two patterns of open/GND application to the CNT terminal.
- the variable setting unit 10 When the variable setting unit 10 is configured to detect the three patterns of application of the power supply voltage Vin/open/GND to the CNT terminal described above, the power supply voltage Vin is applied to the CNT terminal as described above.
- the most frequently used number for example, one
- the second most frequently used number is GND.
- the power supply voltage Vin may be applied to the CNT terminal.
- the LED driving device 15 described so far includes, for example, headlamps (high beam/low beam/small lamps/fog lamps, etc.) X11 of vehicle X10, daytime running lamps ( DRL [daylight running lamps]) X12, tail lamps (including small lamps or back lamps as appropriate) X13, stop lamps X14, turn lamps X15, and the like.
- the LED driving device 15 may be provided as a module (such as the aforementioned socket-type LED module Y) together with the LED light source 200 to be driven, or may be provided as a single IC independent of the LED light source 200. It may be
- the configuration using a light-emitting diode as a light-emitting element was described as an example, but the configuration of the present invention is not limited to this. electro-luminescence) elements can also be used.
- the light-emitting element driving device (15) is a current driver (1) for generating an output current (Iout) flowing through a light emitting element light source (200) connected between a supply voltage (Vin) application terminal and a ground terminal; a first external terminal (ISINK terminal) connectable to a node (Nx) where a high potential side light source (201) and a low potential side light source (202) included in the light emitting element light source are connected in series; a bypass control unit (4) for controlling, in accordance with the power supply voltage, the conduction state of a path for drawing the output current from the first external terminal and bypassing the low-potential-side light source; a constant current source (7) and a switch (8) provided between the power supply voltage application terminal and the first external terminal; a comparator (6) that compares the voltage of the first external terminal and an open detection threshold voltage (Vth_op) and outputs a detection signal; a UVLO unit (2) that compares the
- variable setting unit sets the open detection threshold voltage as the wait time (Twait) for waiting from when the bypass control unit switches the switch to the ON state to when the open determination is performed. It may be configured to be variably set in conjunction with the UVLO threshold voltage (13th configuration).
- the waiting time may be set in consideration of the capacitance of an EMC test countermeasure capacitive element (Csink) externally connectable to the first external terminal (the fourteenth configuration). Constitution).
- Csink EMC test countermeasure capacitive element
- the bypass control unit determines that the UVLO detection signal indicates UVLO cancellation and the light emitting element ON signal (Sled_on) turns on the light emitting element light source.
- the switch may be turned on (a fifteenth configuration).
- a capacitor (Ccrt) and a resistor (Rcrt) can be externally connected, and a triangular wave and a pulse signal corresponding to the triangular wave are generated based on charging of the capacitor and discharging from the capacitor through the resistor.
- a CR timer (9) that generates a PWM dimming signal (Spwm) that is the current driver is on/off controlled based on the PWM dimming signal;
- the light emitting element ON signal is a signal based on the PWM dimming signal,
- the CR timer may be configured to generate the PWM dimming signal with a fixed level in the DC dimming mode (sixteenth configuration).
- a second external terminal (CNT terminal) is further provided, and the variable setting section performs variable setting according to application of a signal to the second external terminal.
- CNT terminal CNT terminal
- a configuration may also be used (17th configuration).
- variable setting unit detects two patterns of application of open/GND (ground potential) to the second external terminal, and performs variable setting according to the detection result. (18th configuration).
- variable setting unit detects three patterns of application of the power supply voltage/open/GND (ground potential) to the second external terminal, and performs variable setting according to the detection result. (19th configuration).
- variable setting unit has a constant current source (10E), and a setting resistor ( Rcnt) to perform variable setting based on the voltage generated at the second external terminal (twentieth configuration).
- the light-emitting device (X1) includes a light-emitting element driving device (15) having any one of the first to ninth configurations and the light-emitting element light source (200) ( 21st configuration).
- the light emitting element light source may be an LED light source (22nd configuration).
- a substrate (300) provided with a wiring pattern for mounting the light emitting element light source and the light emitting element driving device, a socket (900) for mounting the substrate, (23rd configuration).
- the light-emitting element driving device has a second external terminal (CNT terminal) and a heat dissipation pad (150) provided on the bottom surface
- the wiring pattern has a terminal wiring (302A) electrically connected to the second external terminal, and a ground wiring (301) integrated with the terminal wiring and electrically connected to the heat dissipation pad.
- the variable setting unit may detect two patterns of open/GND (ground potential) application to the second external terminal and perform variable setting according to the detection result (24th configuration).
- vehicle (X10) is configured to have the light emitting device (X1) having any one of the 21st to 24th configurations.
- the present disclosure can be used, for example, in a vehicle-mounted light-emitting element driving device.
- LED driving device 10 LED light source 300 substrate 400 LED chip 480 white resin 600 reflector 601 reflective surface 900 socket 910 Mounting part 950 Heat sink B Battery Rset, Rset_th Setting resistors TH1, TH2 Thermistor X1 LED light emitting device X10 Vehicle X11 Head lamp X12 Daytime running lamp X13 Tail lamp X14 Stop lamp X15 Turn lamp Y Socket type LED module
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Abstract
Description
第1設定抵抗に接続可能な第1外部端子と、
発光素子光源の周囲に配置される負特性の第1サーミスタに接続可能な第2外部端子と、
前記第1設定抵抗の抵抗値に基づき設定電流を生成する電流設定部と、
前記第1サーミスタの抵抗値に対して負特性の追加電流を生成する電流追加部と、
前記設定電流と前記追加電流との総和である基準電流に基づき、電源電圧の印加端と接地端との間に接続された前記発光素子光源に流れる出力電流を生成する電流ドライバと、
を有する構成としている。
電源電圧の印加端と接地端との間に接続された発光素子光源に流れる出力電流を生成する電流ドライバと、
前記発光素子光源に含まれる高電位側光源と低電位側光源とが直列に接続されるノードに接続可能な第1外部端子と、
前記電源電圧に応じて、前記第1外部端子から前記出力電流を引き込んで前記低電位側光源をバイパスする経路の導通状態を制御するバイパス制御部と、
前記電源電圧の印加端と前記第1外部端子との間に設けられる定電流源およびスイッチと、
前記第1外部端子の電圧とオープン検出閾値電圧とを比較して検出信号を出力するコンパレータと、
前記電源電圧とUVLO(Under Voltage Lock Out)閾値電圧とを比較してUVLO検出信号を出力するUVLO部と、
前記オープン検出用閾値電圧と前記UVLO閾値電圧を連動して可変設定する可変設定部と、
を有し、
前記電源電圧の立上げ時に、前記バイパス制御部は、前記経路をオフ状態としつつ、前記UVLO検出信号がUVLO解除を示している場合、前記スイッチをオン状態に切り替え、前記第1外部端子の電圧が前記オープン検出閾値電圧を上回っていることを前記検出信号が示している場合、前記ノードより低電位側においてオープンが発生していると判定し、前記経路のオフ状態を維持する構成としている。
以下、第1の技術開示について説明する。
図1は、例示的な実施形態に係るLED発光装置X1の全体構成を示す図である。LED発光装置X1は、バッテリBから電源電圧Vinの供給を受けて点灯する車載ランプである。なお、LED発光装置X1の一例としては、ヘッドランプ、昼間走行用ランプ、テールランプ、ストップランプ、または、ターンランプなどを挙げることができる。上記バッテリは、LED発光装置X1が搭載される車両の電源であり、鉛蓄電池またはリチウムイオン電池などが好適に用いられる。
図2は、電流設定部2および電流追加部3それぞれの具体的な内部構成例を示す図である。
Iset=Vthd/Rset
ただし、Vthd=TH2×Ithd (TH2:サーミスタTH2の抵抗値)
Iadd=Vthd/(Rset_th+TH1) (TH1:サーミスタTH1の抵抗値)
Iref=Iset+Iadd
となる。出力電流Ioutの目標値は、基準電流Irefが大きいほど、大きく設定される(基準電流Irefに対して正特性)。
図7は、これまでに説明してきたLED発光装置X1を具現化した一例として、ソケット型LEDモジュールYを示す平面図である。本構成例のソケット型LEDモジュールYは、例えば車載用の照明器具であって、基板300、LEDチップ400、白色樹脂480、リフレクタ600、LED駆動装置5、および、ソケット900を備えている。ただし、図7に示すLEDチップ400は、図1の例に対応してLED光源10を構成するLEDチップが3個である場合で示しているが、LEDチップの個数はこれに限らない。また、図7においては、LED駆動装置5に対して外付けされる電子部品は便宜上、図示を省略している。
これまでに説明してきたLED駆動装置5は、例えば、図8および図9で示すように、車両X10のヘッドランプ(ハイビーム/ロービーム/スモールランプ/フォグランプなどを適宜含む)X11、昼間走行用ランプ(DRL[daylight running lamps])X12、テールランプ(スモールランプまたはバックランプなどを適宜含む)X13、ストップランプX14、ターンランプX15などの発光装置に組み込んで用いることができる。
以上、例示的な実施形態について説明したが、本発明の趣旨の範囲内において、実施形態は種々に変形が可能である。
以上の通り、例えば、本開示に係る発光素子駆動装置(5)は、
第1設定抵抗(Rset)に接続可能な第1外部端子(SET端子)と、
発光素子光源(10)の周囲に配置される負特性の第1サーミスタ(TH1)に接続可能な第2外部端子(SET_TH端子)と、
前記第1設定抵抗の抵抗値に基づき設定電流(Iset)を生成する電流設定部(2)と、
前記第1サーミスタの抵抗値に対して負特性の追加電流(Iadd)を生成する電流追加部(3)と、
前記設定電流と前記追加電流との総和である基準電流(Iref)に基づき、電源電圧(Vin)の印加端と接地端との間に接続された前記発光素子光源に流れる出力電流(Iout)を生成する電流ドライバ(1)と、
を有する構成としている(第1の構成)。
以下、第2の技術開示について説明する。なお、以下の説明において、構成要素および信号をそれぞれ示す符号については先述した第1の技術開示とは関連性がないものとして扱う。
図10は、例示的な実施形態に係るLED発光装置X1の全体構成を示す図である。LED発光装置X1は、図示しないバッテリから電源電圧Vinの供給を受けて点灯する車載ランプである。なお、LED発光装置X1の一例としては、ヘッドランプ、昼間走行用ランプ、テールランプ、ストップランプ、または、ターンランプなどを挙げることができる。上記バッテリは、LED発光装置X1が搭載される車両の電源であり、鉛蓄電池またはリチウムイオン電池などが好適に用いられる。
ここで、CRタイマ9について、図11を参照して説明する。図11は、CRタイマ9の内部構成例を示す図である。CRタイマ9は、CRT端子およびDISC端子に外付けの部品(キャパシタCcrt、抵抗Rcrt)を接続することでPWM調光を可能とする構成である。
次に、図10に説明を戻し、LED駆動装置15に備えられるバイパス機能について説明する。先述したように、高電位側LED201と低電位側LED202とが接続されるノードNxは、ISINK端子に接続される。
電源電圧Vinが立ち上がるとき(電源電圧Vinの起動時)に、電源電圧Vinが低い期間では定電流回路5をオン状態とすることで低電位側LED202をバイパスし、高電位側LED201を点灯させ、その後、電源電圧Vinが高くなると、定電流回路5をオフ状態に切り替える制御を行う。しかしながら、仮にノードNxより低電位側においてオープンが発生(低電位側LED202におけるオープンを含む)した場合、定電流回路5がオフ状態であると、出力電流Ioutが流れなくなるため、高電位側LED201は消灯する。このような場合、人の目で見ると、瞬間的にLED光源200が点灯した後、消灯してしまう。そこで、本実施形態に係るLED駆動装置15においては、ノードNxより低電位側におけるオープンの発生を検出する機能(オープン検出機能)が備えられている。
Vth_op < Imoni×Twait/C (1)
ただし、C=Cled+Csink
次に、可変設定部10について説明する。
図19は、これまでに説明してきたLED発光装置X1を具現化した一例として、ソケット型LEDモジュールYを示す平面図である。本構成例のソケット型LEDモジュールYは、例えば車載用の照明器具であって、基板300、LEDチップ400、白色樹脂480、リフレクタ600、LED駆動装置15、および、ソケット900を備えている。ただし、図19に示すLEDチップ400は便宜上、LED光源200を構成するLEDチップが3個である場合で示しているが、LEDチップの個数はこれに限らない(図1の例ではLEDチップの個数は4個)。また、図19においては、LED駆動装置15に対して外付けされる電子部品は便宜上、図示を省略している。
これまでに説明してきたLED駆動装置15は、例えば、図22および図23で示すように、車両X10のヘッドランプ(ハイビーム/ロービーム/スモールランプ/フォグランプなどを適宜含む)X11、昼間走行用ランプ(DRL[daylight running lamps])X12、テールランプ(スモールランプまたはバックランプなどを適宜含む)X13、ストップランプX14、ターンランプX15などの発光装置に組み込んで用いることができる。
以上、例示的な実施形態について説明したが、本発明の趣旨の範囲内において、実施形態は種々に変形が可能である。
以上の通り、例えば、本開示に係る発光素子駆動装置(15)は、
電源電圧(Vin)の印加端と接地端との間に接続された発光素子光源(200)に流れる出力電流(Iout)を生成する電流ドライバ(1)と、
前記発光素子光源に含まれる高電位側光源(201)と低電位側光源(202)とが直列に接続されるノード(Nx)に接続可能な第1外部端子(ISINK端子)と、
前記電源電圧に応じて、前記第1外部端子から前記出力電流を引き込んで前記低電位側光源をバイパスする経路の導通状態を制御するバイパス制御部(4)と、
前記電源電圧の印加端と前記第1外部端子との間に設けられる定電流源(7)およびスイッチ(8)と、
前記第1外部端子の電圧とオープン検出閾値電圧(Vth_op)とを比較して検出信号を出力するコンパレータ(6)と、
前記電源電圧とUVLO(Under Voltage Lock Out)閾値電圧(Vin_UVLO)とを比較してUVLO検出信号(Suvlo)を出力するUVLO部(2)と、
前記オープン検出用閾値電圧と前記UVLO閾値電圧を連動して可変設定する可変設定部(10)と、
を有し、
前記電源電圧の立上げ時に、前記バイパス制御部は、前記経路をオフ状態としつつ、前記UVLO検出信号がUVLO解除を示している場合、前記スイッチをオン状態に切り替え、前記第1外部端子の電圧が前記オープン検出閾値電圧を上回っていることを前記検出信号が示している場合、前記ノードより低電位側においてオープンが発生していると判定し、前記経路のオフ状態を維持する構成としている(第12の構成)。
前記PWM調光信号に基づき前記電流ドライバはオンオフ制御され、
前記発光素子オン信号は、前記PWM調光信号に基づく信号であり、
前記CRタイマは、DC調光モードにおいて、レベルを固定した前記PWM調光信号を生成可能である構成としてもよい(第16の構成)。
前記配線パターンは、前記第2外部端子と電気的に接続される端子配線(302A)と、前記端子配線と一体化して前記放熱パッドと電気的に接続されるグランド配線(301)と、を有し、
前記可変設定部は、前記第2外部端子へのオープン/GND(グランド電位)の印加の2つのパターンを検出し、検出結果に応じて可変設定を行う構成としてもよい(第24の構成)。
2 電流設定部
2A 出力トランジスタ
2B エラーアンプ
3 電流追加部
3A 出力トランジスタ
3B エラーアンプ
4 定電流源
5 LED駆動装置
10 LED光源
300 基板
400 LEDチップ
480 白色樹脂
600 リフレクタ
601 反射面
900 ソケット
910 搭載部
950 放熱板
B バッテリ
Rset,Rset_th 設定抵抗
TH1,TH2 サーミスタ
X1 LED発光装置
X10 車両
X11 ヘッドランプ
X12 昼間走行用ランプ
X13 テールランプ
X14 ストップランプ
X15 ターンランプ
Y ソケット型LEDモジュール
Claims (25)
- 第1設定抵抗に接続可能な第1外部端子と、
発光素子光源の周囲に配置される負特性の第1サーミスタに接続可能な第2外部端子と、
前記第1設定抵抗の抵抗値に基づき設定電流を生成する電流設定部と、
前記第1サーミスタの抵抗値に対して負特性の追加電流を生成する電流追加部と、
前記設定電流と前記追加電流との総和である基準電流に基づき、電源電圧の印加端と接地端との間に接続された前記発光素子光源に流れる出力電流を生成する電流ドライバと、
を有する、発光素子駆動装置。 - 前記第2外部端子には、前記第1サーミスタと直列に接続される第2設定抵抗が接続可能であり、
前記電流追加部は、前記第1サーミスタと前記第2設定抵抗との合成抵抗値に対して負特性の前記追加電流を生成する、請求項1に記載の発光素子駆動装置。 - 前記発光素子光源の周囲に配置される負特性の第2サーミスタに接続可能な第3外部端子と、
前記第3外部端子に接続される定電流源と、
をさらに有し、
前記電流追加部は、前記第3外部端子の端子電圧に対して正特性の前記追加電流を生成する、請求項2に記載の発光素子駆動装置。 - 前記電流設定部は、前記端子電圧に対して正特性の前記設定電流を生成する、請求項3に記載の発光素子駆動装置。
- 前記電流設定部は、
前記設定電流が流れる経路に配置される第1出力トランジスタと、
前記第1出力トランジスタの第1端と前記第1外部端子とが接続される第1ノードに接続される第1入力端と、前記端子電圧の印加端に接続される第2入力端と、前記第1出力トランジスタの制御端に接続される出力端と、を含む第1エラーアンプと、
を有する、請求項4に記載の発光素子駆動装置。 - 前記電流追加部は、
前記追加電流が流れる経路に配置される第2出力トランジスタと、
前記第2出力トランジスタの第1端と前記第2外部端子とが接続される第2ノードに接続される第1入力端と、基準電圧の印加端に接続される第2入力端と、前記第2出力トランジスタの制御端に接続される出力端と、を含む第2エラーアンプと、
を有する、請求項1から請求項5のいずれか1項に記載の発光素子駆動装置。 - 前記発光素子光源の周囲に配置される負特性の第2サーミスタに接続可能な第3外部端子と、
前記第3外部端子に接続される定電流源と、
をさらに有し、
前記第2外部端子には、前記第1サーミスタと直列に接続される第2設定抵抗が接続可能であり、
前記基準電圧は、前記第3外部端子の端子電圧である、請求項6に記載の発光素子駆動装置。 - 請求項1から請求項7のいずれか1項に記載の発光素子駆動装置と、前記発光素子光源と、を有する、発光装置。
- 前記発光素子光源は、LED光源である、請求項8に記載の発光装置。
- 前記発光素子光源と前記発光素子駆動装置を実装するための配線パターンが設けられた基板と、
前記基板を搭載するソケットと、
をさらに有する、請求項8または請求項9に記載の発光装置。 - 請求項8から請求項10のいずれか1項に記載の発光装置を有する車両。
- 電源電圧の印加端と接地端との間に接続された発光素子光源に流れる出力電流を生成する電流ドライバと、
前記発光素子光源に含まれる高電位側光源と低電位側光源とが直列に接続されるノードに接続可能な第1外部端子と、
前記電源電圧に応じて、前記第1外部端子から前記出力電流を引き込んで前記低電位側光源をバイパスする経路の導通状態を制御するバイパス制御部と、
前記電源電圧の印加端と前記第1外部端子との間に設けられる定電流源およびスイッチと、
前記第1外部端子の電圧とオープン検出閾値電圧とを比較して検出信号を出力するコンパレータと、
前記電源電圧とUVLO(Under Voltage Lock Out)閾値電圧とを比較してUVLO検出信号を出力するUVLO部と、
前記オープン検出用閾値電圧と前記UVLO閾値電圧を連動して可変設定する可変設定部と、
を有し、
前記電源電圧の立上げ時に、前記バイパス制御部は、前記経路をオフ状態としつつ、前記UVLO検出信号がUVLO解除を示している場合、前記スイッチをオン状態に切り替え、前記第1外部端子の電圧が前記オープン検出閾値電圧を上回っていることを前記検出信号が示している場合、前記ノードより低電位側においてオープンが発生していると判定し、前記経路のオフ状態を維持する、発光素子駆動装置。 - 前記可変設定部は、前記バイパス制御部が前記スイッチをオン状態に切り替えてからオープン判定を行うまでに待機する待ち時間を前記オープン検出用閾値電圧と前記UVLO閾値電圧と連動して可変設定する、請求項12に記載の発光素子駆動装置。
- 前記待ち時間は、前記第1外部端子に外部接続可能なEMCテスト対策用容量素子の容量を考慮して設定される、請求項13に記載の発光素子駆動装置。
- 前記バイパス制御部は、前記UVLO検出信号がUVLO解除を示しており、かつ、発光素子オン信号が前記発光素子光源のオンを示している場合に、前記スイッチをオン状態に切り替える、請求項12から請求項14のいずれか1項に記載の発光素子駆動装置。
- キャパシタおよび抵抗を外部接続可能で、前記キャパシタの充電および前記キャパシタからの前記抵抗を介した放電に基づき三角波および前記三角波に応じたパルス信号であるPWM調光信号を生成するCRタイマをさらに有し、
前記PWM調光信号に基づき前記電流ドライバはオンオフ制御され、
前記発光素子オン信号は、前記PWM調光信号に基づく信号であり、
前記CRタイマは、DC調光モードにおいて、レベルを固定した前記PWM調光信号を生成可能である、請求項15に記載の発光素子駆動装置。 - 第2外部端子をさらに有し、
前記可変設定部は、前記第2外部端子への信号印加に応じて可変設定を行う、請求項12から請求項16のいずれか1項に記載の発光素子駆動装置。 - 前記可変設定部は、前記第2外部端子へのオープン/GND(グランド電位)の印加の2つのパターンを検出し、検出結果に応じて可変設定を行う、請求項17に記載の発光素子駆動装置。
- 前記可変設定部は、前記第2外部端子への前記電源電圧/オープン/GND(グランド電位)の印加の3つのパターンを検出し、検出結果に応じて可変設定を行う、請求項17に記載の発光素子駆動装置。
- 前記可変設定部は、定電流源を有し、前記定電流源による定電流を前記第2外部端子に外部接続可能な設定用抵抗に流すことにより前記第2外部端子に発生する電圧に基づき可変設定を行う、請求項17に記載の発光素子駆動装置。
- 請求項12から請求項20のいずれか1項に記載の発光素子駆動装置と、前記発光素子光源と、を有する、発光装置。
- 前記発光素子光源は、LED光源である、請求項21に記載の発光装置。
- 前記発光素子光源と前記発光素子駆動装置を実装するための配線パターンが設けられた基板と、
前記基板を搭載するソケットと、
をさらに有する、請求項21または請求項22に記載の発光装置。 - 前記発光素子駆動装置は、第2外部端子と、下面に設けられた放熱パッドと、を有し、
前記配線パターンは、前記第2外部端子と電気的に接続される端子配線と、前記端子配線と一体化して前記放熱パッドと電気的に接続されるグランド配線と、を有し、
前記可変設定部は、前記第2外部端子へのオープン/GND(グランド電位)の印加の2つのパターンを検出し、検出結果に応じて可変設定を行う、請求項23に記載の発光装置。 - 請求項21から請求項24のいずれか1項に記載の発光装置を有する車両。
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JP2012160277A (ja) * | 2011-01-31 | 2012-08-23 | Koito Mfg Co Ltd | 半導体光源点灯回路 |
JP2014154472A (ja) * | 2013-02-13 | 2014-08-25 | Panasonic Corp | 点灯装置及びそれを用いた照明器具 |
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JP2012160277A (ja) * | 2011-01-31 | 2012-08-23 | Koito Mfg Co Ltd | 半導体光源点灯回路 |
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