JP2014238024A - Switch control circuit, igniter, engine ignition device, and vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a switch control circuit with a software cutoff function which is easily integrated.SOLUTION: A switch control circuit 11 has: an output part 112 for generating an on/off signal Sg of a switch element 12; a software cutoff part 116 which includes a variable resistance RV forming a resistive voltage dividing circuit together with a resistor element RH of the output part 112 and, by switching resistance values of the variable resistance RV stepwise when the switch element 12 is forcibly turned off, gradually shifts the signal level of the on/off signal Sg determined by the resistive voltage dividing circuit; and a control unit 111 for controlling the output part 112 and the software cutoff part 116.

Description

  The present invention relates to a switch control circuit.

  An igniter constituting an engine ignition device of a vehicle includes an IGBT (insulated gate bipolar transistor) and a MOSFET (metal oxide semiconductor field effect transistor) according to an ignition instruction signal IGT [iginition timing signal] from an ECU [engine control unit]. A switch control circuit for turning on / off the switch elements is incorporated.

JP 2011-124269 A

  By the way, many of the above-described switch control circuits are configured to forcibly turn off the switch element when a certain abnormality (such as a logical abnormality of the ignition instruction signal IGT or a temperature abnormality of the switch control circuit) occurs, and to reduce a current flowing through the switch element. It has an abnormal protection function to shut off.

  However, if the switch element is sharply turned off during the abnormality protection operation, an excessive secondary voltage is generated in the ignition coil, which may cause the ignition plug to be erroneously ignited. Therefore, in the conventional switch control circuit, in order to prevent the generation of an excessive secondary voltage, a current interruption operation (so-called soft interruption (soft shut-off)) that gently interrupts the current flowing through the switch element has been performed. .

  As a method for realizing the above-described soft shut-off, an RC time constant circuit composed of a resistor R and a capacitor C is used, so that the control signal of the switch element can be obtained with a time constant τ (= R × C) of about 10 ms to 100 ms. A method of gently reducing (IGBT gate signal) is conceivable. However, in order to obtain the above time constant τ using the RC time constant circuit, a resistance R of several tens of megaΩ or a capacitance C of nano-order or more is required, which is a factor that hinders integration of the switch control circuit. It was one.

  Patent Document 1 discloses an igniter power semiconductor device that limits the current flowing through the IGBT to a value lower than that during normal operation in accordance with the detected temperature. However, the current limiting method variably controls the current for generating the gate voltage of the IGBT, and has an essential configuration different from that of the present invention described later.

  In view of the above-mentioned problems found by the inventors of the present application, the present invention provides a switch control circuit with a soft shut-off function that can be easily integrated, and an igniter, an engine ignition device, and a vehicle using the switch control circuit. With the goal.

  The switch control circuit disclosed in the present specification includes an output unit that generates an on / off signal of a switch element; and a variable resistor that forms a resistance voltage dividing circuit together with a resistance element of the output unit. A soft shut-off unit that gradually changes the signal level of the on / off signal determined by the resistance voltage-dividing circuit by switching the resistance value of the variable resistor stepwise at the time of forced off; and the output unit and the soft shut-off unit And a control unit (first configuration).

  In the switch control circuit having the first configuration, the soft shut-off unit transitions the on / off signal from the signal level at the time of on to the on threshold level of the switch element at a stroke, and then at the time of further off. A configuration (second configuration) in which the signal level is gradually changed may be used.

  Further, in the switch control circuit having the first or second configuration, the soft cutoff unit is configured to gently transition the signal level of the on / off signal with a behavior simulating a time constant circuit or a linear behavior. (Third configuration) is preferable.

  In the switch control circuit having any one of the first to third configurations, the control unit functions as a pre-driver unit that controls the output unit in response to an ignition instruction signal, and the ignition instruction signal is turned on. It is preferable to adopt a configuration (fourth configuration) having a function as a timer protection unit that forcibly turns off the switch element when a predetermined standby time has passed with the current logic level maintained.

  In the switch control circuit having any one of the first to fourth configurations, the variable resistor includes a plurality of resistors connected in parallel to the control terminal of the switch element, and a current path for each resistor. A configuration (fifth configuration) including a plurality of switches that conduct / shut off may be used.

  In the switch control circuit having any one of the first to fifth configurations, the output unit includes an upper transistor connected between the upper power supply terminal and the control terminal of the switch element, and a lower power supply terminal. A configuration (sixth configuration) including a lower transistor connected between the control ends of the switch elements and a current limiting resistor connected to the control ends of the switch elements is preferable.

  Further, the switch control circuit having any one of the first to sixth configurations may be configured to be integrated on a semiconductor chip (seventh configuration).

  The igniter disclosed in the present specification has a configuration (eighth configuration) formed by packaging the switch element and the switch control circuit having the seventh configuration.

  The engine ignition device disclosed in the present specification includes an ignition coil, an igniter having the eighth configuration for turning on / off a current flowing in a primary coil of the ignition coil, and a secondary of the ignition coil. It is set as the structure (9th structure) which has a spark plug connected to a side coil.

  A vehicle disclosed in the present specification includes an engine ignition device having the ninth configuration, a car battery that supplies electric power to the engine ignition device, an engine control unit that controls the engine ignition device, It is set as the structure (10th structure) which has.

  According to the present invention, it is possible to provide a switch control circuit with a soft cutoff function that can be easily integrated, an igniter, an engine ignition device, and a vehicle using the switch control circuit.

The block diagram which shows the whole structure of the vehicle X provided with the engine ignition device 1 The circuit diagram which shows one structural example of the switch control circuit 11 Timing chart showing an example of switch control operation Circuit diagram showing a configuration example of the soft shut-off unit 116 Timing chart showing an example of soft shutoff operation Waveform diagram showing first falling pattern of gate signal Sg Timing chart showing relationship between ignition instruction signal Sc and collector current Ic Timing chart showing second fall pattern of gate signal Sg External view showing a configuration example of the vehicle X

<Overall configuration>
FIG. 1 is a block diagram showing an overall configuration of a vehicle X provided with an engine ignition device 1. The engine ignition device 1 is used in a form mounted on the vehicle X together with the car battery 2 and the ECU 3. In the following description, an element that functions as a resistor on an electric circuit is generalized and referred to as a “resistance element”, and an element that functions as a capacitor (including parasitic capacitance) is generalized and referred to as a “capacitance element”. There is.

  As shown in FIG. 1, the engine ignition device 1 includes an igniter 10, an ignition coil 20, and a spark plug 30.

  The igniter 10 is provided as a semiconductor integrated circuit device in which a switch control circuit 11, a switch element 12, and a resistance element 13 are packaged.

  The switch control circuit 11 is formed as an LSI chip, and has a function (gate control function) for generating a gate signal Sg of the switch element 12 in response to an ignition instruction signal Sc input from the ECU 3. Further, the switch control circuit 11 monitors the detection voltage (emitter voltage) Ve corresponding to the collector current Ic (emitter current Ie) of the switch element 12, and according to the monitoring result, the collector current Ic is less than or equal to a predetermined upper limit value Ilmt. The function to restrict to (IGBT protection function at the time of abnormality) is provided. Further, the switch control circuit 11 forcibly turns off the switch element 12 when the predetermined standby time has passed while the ignition instruction signal Sc is kept at the logic level (for example, high level) at the time of ON, and the collector current Ic. (Timer protection function) is also provided. The configuration and operation of the switch control circuit 11 will be described later.

  Although not depicted in this figure, when it is necessary to make the igniter 10 compatible with an electronic fuel injection device (EFI), the switch control circuit 11 sends an ignition confirmation signal IGF to the ECU. A function for sending [ignition confirmation signal] may be added.

  The switch element 12 is a switch element that is turned on / off by the switch control circuit 11, and an IGBT is employed in FIG. The switch element 12 has a gate connected to the switch control circuit 11, a collector connected to the primary coil 21 of the ignition coil 20, and an emitter connected to the resistance element 13 (for example, the emitter of the IGBT and the GND frame). The wire is grounded via a resistance component). Note that a MOSFET may be employed as the switch element 12.

  The ignition coil 20 includes a primary coil 21 having a winding number N1 and a secondary coil 22 having a winding number N2 (> N1). The power supply voltage Vcc supplied from the car battery 2 is changed to a higher secondary voltage Vsp. It plays the role of converting (boosting). The first end of the primary side coil 21 and the first end of the secondary side coil 22 are both connected to the car battery 2. The second end of the primary coil 21 is connected to the collector of the switch element 12. The second end of the secondary coil 22 is connected to the spark plug 30, and the secondary voltage Vsp generated in the secondary coil 22 is supplied to the spark plug 30.

  The spark plug 30 uses the secondary voltage Vsp obtained by the ignition coil 20 to generate a spark for igniting the engine (not shown in FIG. 1) of the vehicle X.

  The car battery 2 is a power source for supplying power to various electrical components mounted on the vehicle X including the engine ignition device 1.

  The ECU 3 executes various controls related to the engine drive of the vehicle X. In particular, the ECU 3 outputs an ignition instruction signal Sc used for operation control of the igniter 10 (particularly, the switch control circuit 11) as one of the various controls. Specifically, the ECU 3 sets the ignition instruction signal Sc to a logic level (eg, high level) when the switch element 12 is turned on, and sets the ignition instruction signal Sc when the switch element 12 is turned off. A logic level (for example, a low level) is set.

<Switch control circuit>
FIG. 2 is a circuit diagram illustrating a configuration example of the switch control circuit 11. The switch control circuit 11 of this configuration example includes a control unit 111, a totem pole output unit 112, an oscillation unit 113, a current detection unit 114, a current limiting unit 115, and a soft cutoff unit 116 as main circuit elements. ,including. Further, the switch control circuit 11 of this configuration example has a gate control pad 11a, an emitter voltage detection pad 11b, a grounding pad 11c, a power supply pad 11d, as means for establishing electrical connection with the outside, And a signal input pad 11e.

  The control unit 111 functions as a pre-driver unit that generates drive signals (gate signals GH and GL) of the totem pole output unit 112 in response to the ignition instruction signal Sc input from the ECU 3 through the signal input pad 11e. I have. Further, the control unit 111 includes a timer 111a (counter) that counts the number of pulses of the clock signal CLK, and also has a function as a timer protection unit that generates the soft cutoff signal ST according to the count value.

  The totem pole output unit 112 includes a P-channel MOS field effect transistor MH and an N-channel MOS field effect transistor ML (corresponding to an upper transistor and a lower transistor) forming a CMOS [Complementary MOS] structure, a current limiting resistor RH, and Includes RL. The source of the transistor MH is connected to the application terminal (corresponding to the upper power supply terminal) of the power supply voltage Vcc through the power supply pad 11d. The drain of the transistor MH is connected to the first end of the current limiting resistor RH. The second end of the current limiting resistor RH and the first end of the current limiting resistor RL are connected to each other, and the connection node is connected to the gate of the switch element 12 through the gate control pad 11a. The second end of the current limiting resistor RL is connected to the drain of the transistor ML. The source of the transistor ML is connected to the ground terminal (corresponding to the lower power supply terminal) via the ground pad 11c. The gates of the transistors MH and ML are connected to the application terminals of the gate signals GH and GL, respectively. When the current limiting resistors RH and RL are replaced with a single current limiting resistor, a single current limiting resistor may be inserted between the connection node of the transistors MH and ML and the gate of the switch element 12.

  The oscillation unit 113 outputs a clock signal CLK having a predetermined frequency to the control unit 111.

  The current detection unit 114 detects the state of the collector current Ic (emitter current Ie) by monitoring the detection voltage Ve input via the emitter voltage detection pad 11b, and generates a current limiting signal Sd according to the detection result. To do. The current limiting signal Sd is at a low level when the collector current Ic is smaller than the upper limit value Ilmt, and is at a high level when the collector current Ic is larger than the upper limit value Ilmt.

  When the current limiting signal Sd rises to a high level during the ON period of the switch element 12, the current limiting unit 115 limits the collector current Ic to the upper limit value Ilmt or less by lowering the high level of the gate signal Sg than normal. To do. As a method for lowering the high level of the gate signal Sg, either resistance saturation or switch control may be employed.

  The soft shut-off unit 116 includes a variable resistor RV that forms a resistance voltage dividing circuit together with a resistance element (for example, a current limiting resistor RH) of the totem pole output unit 112, and when the switch element 12 is forcibly turned off by an abnormal protection operation. The resistance value of the variable resistor RV is lowered stepwise in accordance with the soft cutoff signal ST input from the control unit 111. As a result, the signal level (= α × Vcc) of the gate signal Sg determined according to the voltage dividing ratio α (= RV / (RH + RV)) of the resistance voltage dividing circuit is changed from the signal level at the time of ON (eg, Vcc) to the signal at the time of OFF. Since it can be lowered step by step to a level (for example, GND), the collector current Ic can be gradually cut off. The configuration and operation of the soft blocking unit 116 will be described later.

  FIG. 3 is a timing chart showing an example of the switch control operation. The ignition instruction signal Sc, the gate signal Sg, the collector voltage Vc, the secondary voltage Vsp, the current limit signal Sd, and the collector current Ic are sequentially shown from the top. It is depicted.

  At time t1, when the ignition instruction signal Sc is switched to a logical level (for example, high level) at the time of ON, the control unit 111 turns on the transistor MH and turns off the transistor ML. As a result, the gate signal Sg becomes high level (approximately the power supply voltage Vcc), and the switch element 12 is turned on. Therefore, the collector current Ic (emitter current Ie) flows from the car battery 2 through the primary coil 21 of the ignition coil 20, the switch element 12, and the resistance element 13 to the ground terminal, and flows to the primary coil 21. Energy is stored.

  After that, at time t2, when the ignition instruction signal Sc is switched to a logical level (for example, low level) at the time of OFF, the control unit 111 turns off the transistor MH and turns on the transistor ML. As a result, the gate signal Sg becomes a low level (almost the ground voltage GND), and the switch element 12 is turned off. At this time, a large counter electromotive force is generated in the primary coil 21 due to the self-induction action, and the collector voltage Vc rapidly increases. Further, a larger electromotive force is generated in the secondary coil 22 according to the turn ratio (N2 / N1) due to the mutual induction action with the primary coil 21. Due to the electromotive force of the secondary coil 22 generated in this way, a very high secondary voltage Vsp (10,000 volts or more) is applied to the spark plug 30, and a spark is generated to ignite the engine. .

  At times t1 to t2, the high level period T1 of the ignition instruction signal Sc is as short as about several ms, and the collector current Ic does not reach the upper limit value Ilmt, so the current limit signal Sd is maintained at the low level. Accordingly, the high level of the gate signal Sg remains at the normal level without being lowered.

  On the other hand, after time t3, the high level period of the ignition instruction signal Sc is long, and at time t4, the collector current Ic reaches the upper limit value Ilmt. As a result, after time t4, the current limit signal Sd rises to a high level and the high level of the gate signal Sg is lowered with an appropriate time constant, so that the collector current Ic is limited to the upper limit value Ilmt.

  When a predetermined standby time T2 (about 100 ms) elapses with the ignition instruction signal Sc kept at a high level due to a malfunction of the ECU 3 or the like, at time t5, the switch element 12 is forcibly turned off and the collector current Ic An abnormal protection operation (timer protection operation) that shuts off is activated. However, if the switch element 12 is sharply turned off during the abnormality protection operation, an excessive secondary voltage Vsp is generated in the ignition coil 20 and there is a possibility that the ignition plug 30 may be erroneously ignited (see the broken line in the figure).

  Therefore, the switch control circuit 11 is provided with a soft cutoff unit 116 that gently cuts off the collector current Ic over the soft cutoff time T3 (10 ms to 100 ms), as shown at times t5 to t6. Hereinafter, the configuration and operation of the soft blocking unit 116 will be described in detail.

<Soft shut-off section>
FIG. 4 is a circuit diagram illustrating a configuration example of the soft shut-off unit 116. The soft cutoff unit 116 of this configuration example includes n (where n ≧ 2) resistors R1 to Rn connected in parallel to the gate of the switch element 12 as circuit elements that form the above-described variable resistor RV. N n-channel MOS field effect transistors M1 to Mn (corresponding to switches) that conduct / shut off the current paths for the resistors R1 to Rn.

  The connection relationship between circuit elements will be specifically described. The first ends of the resistors R1 to Rn are all connected to the gate of the switch element 12. The second ends of the resistors R1 to Rn are connected to the drains of the transistors M1 to Mn, respectively. The sources of the transistors M1 to Mn are all connected to the ground terminal. The gates of the transistors M1 to Mn are all connected to the control unit 111, and the soft cutoff signals ST1 to STn (corresponding to the above-described soft cutoff signal ST) are respectively applied thereto. The transistors M1 to Mn are turned on when the soft cutoff signals ST1 to STn are at a high level, and are turned off when the soft cutoff signals ST1 to STn are at a low level. Also, the on-resistance values of the transistors M1 to Mn are assumed to be negligible compared to the resistance values (several kΩ) of the resistors R1 to Rn.

  FIG. 5 is a timing chart showing an example of the soft shut-off operation. In order from the top, the ignition instruction signal Sc, the gate signals GH and GL, the clock signal CLK, the count value (TM_count) of the timer 111a, and the soft shut-off signal ST1. ~ STn is depicted.

  When the ignition instruction signal Sc rises to a high level at time t11, both the gate signals GH and GL are lowered to a low level, so that the transistor MH is turned on and the transistor ML is turned off. At this time, the soft cutoff signals ST1 to STn are all at a low level. Therefore, the gate signal Sg is at a high level (approximately the power supply voltage Vcc), and the switch element 12 is turned on. Further, after time t11, the timer 111a starts pulse counting of the clock signal CLK. The count value of the timer 111a may be reset to a zero value at the pulse edge (rising edge or falling edge) of the ignition instruction signal Sc.

  Thereafter, when the count value of the timer 111a reaches the predetermined value x at time t12, the switch element 12 is forcibly turned off based on the determination that the standby time T2 has passed while the ignition instruction signal Sc remains at the high level. Thus, an abnormal protection operation (timer protection operation) for interrupting the collector current Ic is activated.

  First, at times t12 to t13 (corresponding to the pulse period of the clock signal CLK), the soft cutoff signal ST1 is set to the high level while the gate signals GH and GL are maintained at the low level, and the remaining soft cutoff signals ST2 to ST2 are maintained. Both STn are set to the low level. At this time, since the resistance voltage dividing circuit is formed by the current limiting resistor RH and the resistor R1, the signal level of the gate signal Sg is a voltage V1 (= {R1 / (RH + R1)}) that is lowered by one step from the power supply voltage Vcc. Vcc) (see FIG. 6).

  Next, at times t13 to t14, the soft cutoff signal ST2 is set to the high level while the gate signals GH and GL are maintained at the low level, and the remaining soft cutoff signals ST1 and ST3 to STn are all set to the low level. Is done. At this time, since a resistance voltage dividing circuit is formed by the current limiting resistor RH and the resistor R2 (<R1), the signal level of the gate signal Sg is further reduced by one step from the voltage V1 to the voltage V2 (= {R2 / ( RH + R2)} × Vcc) (see FIG. 6).

  Next, at times t14 to t15, the soft cutoff signal ST3 is set to the high level while the gate signals GH and GL are maintained at the low level, and the remaining soft cutoff signals ST1 and ST2 and ST4 to STn are all low. Level. At this time, since a resistance voltage dividing circuit is formed by the current limiting resistor RH and the resistor R3 (<R2 <R1), the signal level of the gate signal Sg is a voltage V3 (= {R3) further lowered by one step from the voltage V2. / (RH + R3)} × Vcc) (see FIG. 6).

  Similarly, the resistance value of the variable resistor RV is decreased step by step for every pulse period of the clock signal CLK, and the signal level of the gate signal Sg is gradually decreased. At times t16 to t17, the soft cutoff signal STn is set to the high level while the gate signals GH and GL are maintained at the low level, and the remaining soft cutoff signals ST1 to ST (n-1) are all low. Level. At this time, the signal level of the gate signal Sg is the lowest voltage Vn (= {Rn / (RH + Rn)} × Vcc) within the variable range.

  Thereafter, at times t17 to t18, the gate signal GH is raised to a high level while the logic levels of the soft cutoff signals ST1 to STn are maintained, and the transistor MH is turned off. As a result, the connection between the application terminal of the power supply voltage Vcc and the gate of the switch element 12 is cut off, so that the gate signal Sg further decreases. By providing such a period, the gate signal Sg can be sufficiently lowered before the transistor ML is turned on.

  At time t18, the soft cutoff signal STn is lowered to the low level and the gate signal GL is raised to the high level. As a result, the gate of the switch element 12 is electrically connected to the ground terminal, so that the gate signal Sg is lowered to a low level (substantially the ground voltage GND).

  In the case of the switch control circuit 11 of this configuration example, unlike the conventional configuration in which the gate signal Sg is blunted using an RC time constant circuit, resistances R1 to Rn (for example, 4 bits and 16 gradations) of several kΩ are used. Since a soft cutoff time T3 of 10 ms to 100 ms can be realized, integration on a semiconductor chip is facilitated. Further, by designing the circuit of the oscillation unit 117 so that the oscillation frequency of the clock signal CLK does not have temperature dependence, it is possible to increase the accuracy of the soft cutoff time T3.

  In the above-described embodiment, a configuration in which the resistance value of the variable resistor RV is reduced stepwise by sequentially selecting the resistors R1 to Rn in descending order of the resistance value is given as an example. The method of changing the value is not limited to this. For example, the resistance value of the variable resistor RV (= the combined resistance value of the selected resistor) is selected by simultaneously selecting the resistors R1 to Rn in any combination. It may be configured to pull down in stages.

  FIG. 6 is a waveform diagram showing a first falling pattern of the gate signal Sg. As shown in the figure, the first falling pattern is a behavior simulating an RC time constant circuit, and the signal level of the gate signal Sg is gradually changed from the signal level (Vcc) when turned on to the signal level (GND) when turned off. It is set as the structure pulled down to.

  If the first falling pattern is adopted, the behavior similar to the conventional configuration in which the gate signal Sg is blunted using the RC time constant circuit can be realized in a simulated manner, so that the adaptability to the existing set is high. it is conceivable that.

  However, the falling pattern of the gate signal Sg is not limited to this. For example, the signal level of the gate signal Sg may be linearly lowered (see FIG. 8 described later). Absent.

  In the first falling pattern, the state of performing soft cutoff (lowering of the gate signal Sg) is described starting from the signal level (Vcc) at the time of ON, but the starting point of soft cutoff is not necessarily limited to this. . Hereinafter, this point will be described in detail with reference to FIG.

  FIG. 7 is a timing chart showing the relationship between the ignition instruction signal Sc and the collector current Ic. From the top, the ignition instruction signal Sc, the gate-emitter voltage VGE and the collector-emitter voltage VCE of the switch element 12, and The collector current Ic is depicted.

  When the ignition instruction signal Sc rises to a high level at time t21, the gate-emitter voltage VGE of the switch element 12 does not rise uniformly to a high level, but is once flat near the on-threshold level Vth of the switch element 12. (See times t22 to t23). Further, when the ignition instruction signal Sc falls to the low level at time t24, the gate-emitter voltage VGE of the switch element 12 does not uniformly fall to the low level as described above, but the switch element 12 And once flat near the on-threshold level Vth (see times t25 to t26). Such a behavior inevitably occurs due to a capacitance difference between the input capacitance Cies and the output capacitance Coes (see FIG. 4 above) associated with the switch element 12.

  Here, in order to prevent erroneous ignition of the spark plug 30 when the switch element 12 is forcibly turned off, the collector current Ic is gently lowered in the subsequent period when the gate-emitter voltage VGE falls below the on-threshold level Vth. It is important that the collector current Ic be gently lowered in the period before the gate-emitter voltage VGE falls below the on-threshold level Vth. Based on such considerations, a second falling pattern of the gate signal Sg is proposed below.

  FIG. 8 is a timing chart showing a second falling pattern of the gate signal Sg, in which the gate-emitter voltage VGE (corresponding to the gate signal Sg) of the switch element 12 and the collector current Ic are depicted in order from the top. Yes.

  As shown in the figure, after the second falling pattern, at time t31, the gate-emitter voltage VGE is lowered from the on-level signal level (Vcc) to the on-threshold level (Vth) of the switch element 12 at once. A configuration in which the gate-emitter voltage VGE is gradually lowered to the off-time signal level (GND) over the soft cutoff time T3 (time t31 to t32), in other words, the on-threshold level (Vth) of the switch element 12 As a starting point, the soft cutoff of the collector current Ic is performed.

  If the second falling pattern is adopted, the number of gradations of the variable resistor RV is unnecessarily increased as compared with the configuration in which the soft cutoff is performed with the signal level (Vcc) at the time of ON as the starting point (first falling pattern). Therefore, the circuit scale of the soft shut-off unit 116 can be reduced.

<Vehicle>
FIG. 9 is an external view showing a configuration example of the vehicle X. The vehicle X in this configuration example includes in-vehicle devices X11 to X17 and a battery (corresponding to the car battery 2 in FIG. 1, not shown in FIG. 9) that supplies power to these in-vehicle devices X11 to X17. Yes.

  The in-vehicle device X11 is an engine control unit (corresponding to the ECU 3 in FIG. 1) that performs control related to the engine (injection control, electronic throttle control, idling control, oxygen sensor heater control, auto cruise control, etc.). The engine ignition device 1 mounted on the vehicle X is controlled by the engine control unit.

  The in-vehicle device X12 is a lamp control unit that performs on / off control such as HID [high intensity discharged lamp] and DRL [daytime running lamp].

  The in-vehicle device X13 is a transmission control unit that performs control related to the transmission.

  The in-vehicle device X14 is a body control unit that performs control (ABS [anti-lock brake system] control, EPS [electric power Steering] control, electronic suspension control, etc.) related to the motion of the vehicle X.

  The in-vehicle device X15 is a security control unit that performs drive control such as a door lock and a security alarm.

  The in-vehicle device X16 is an electronic device incorporated in the vehicle X at the factory shipment stage as a standard equipment item or a manufacturer option product such as a wiper, an electric door mirror, a power window, an electric sunroof, an electric seat, and an air conditioner.

  The in-vehicle device X17 is an electronic device that is arbitrarily attached to the vehicle X by the user, such as an in-vehicle A / V [audio / visual] device, a car navigation system, and an ETC [electronic toll collection system].

<Other variations>
The configuration of the present invention can be variously modified in addition to the above-described embodiment without departing from the gist of the invention. That is, the above-described embodiment is an example in all respects and should not be considered as limiting, and the technical scope of the present invention is not the description of the above-described embodiment, but the claims. It should be understood that all modifications that come within the meaning and range of equivalents of the claims are included.

  The present invention can be used for an igniter, for example.

1 Engine ignition device 2 Car battery 3 ECU
DESCRIPTION OF SYMBOLS 10 Igniter 11 Switch control circuit 11a Gate control pad 11b Emitter voltage detection pad 11c Grounding pad 11d Power supply pad 11e Signal input pad 111 Control part (pre-driver part, timer protection part)
111a timer 112 totem pole output unit 113 oscillating unit 114 current detecting unit 115 current limiting unit 116 soft cutoff unit 12 switch element 13 resistance element 20 ignition coil 21 primary side coil 22 secondary side coil 30 ignition plug MH P channel type MOS field effect Transistor (upper transistor)
ML N-channel MOS field effect transistor (lower transistor)
RH, RL Current limiting resistance RV Variable resistance R1-Rn Resistance M1-Mn N-channel MOS field effect transistor (switch)
X Vehicle X11-X17 In-vehicle equipment

Claims (10)

An output for generating an on / off signal of the switch element;
A variable resistor that forms a resistance voltage dividing circuit together with the resistance element of the output unit; and by switching the resistance value of the variable resistor stepwise when the switch element is forcibly turned off, the on / off value determined by the resistance voltage dividing circuit A soft shut-off section that gently transitions the signal level of the off signal;
A control unit for controlling the output unit and the soft shut-off unit;
A switch control circuit comprising:   The soft shut-off unit, after making a transition from the signal level at the time of on-off to the on-threshold level of the switch element at a stroke, further makes a transition from the signal level at the time of off gradually. 2. The switch control circuit according to 1.   3. The switch control circuit according to claim 1, wherein the soft shut-off unit gently transitions the signal level of the on / off signal with a behavior simulating a time constant circuit or a linear behavior. 4. .   The control unit functions as a pre-driver unit that controls the output unit in response to an ignition instruction signal, and the switch when a predetermined standby time elapses while the ignition instruction signal remains at a logical level when on. The switch control circuit according to claim 1, further comprising a function as a timer protection unit for forcibly turning off the element. The variable resistor is
A plurality of resistors connected in parallel to the control end of the switch element;
A plurality of switches for conducting / interrupting the current path for each resistor;
The switch control circuit according to claim 1, comprising: The output unit is
An upper transistor connected between an upper power supply terminal and a control terminal of the switch element;
A lower transistor connected between a lower power supply terminal and a control terminal of the switch element;
A current limiting resistor connected to the control end of the switch element;
The switch control circuit according to claim 1, comprising:   7. The switch control circuit according to claim 1, wherein the switch control circuit is integrated on a semiconductor chip. A switch element;
A switch control circuit according to claim 7;
An igniter characterized by being packaged. Ignition coil,
The igniter according to claim 8 for turning on / off a current flowing through a primary side coil of the ignition coil,
A spark plug connected to the secondary coil of the ignition coil;
An engine ignition device comprising: The engine ignition device according to claim 9,
A car battery for supplying electric power to the engine ignition device;
An engine control unit for controlling the engine ignition device;
The vehicle characterized by having.

Images