JPH01301432A - Intelligent power ic for electric equipment of vehicle - Google Patents

Abstract

PURPOSE:To dissolve the problems of response delay, faulty operation and malfunction even when the overload current flows by incorporating a two-stage overcurrent detecting circuit able to be switched for the loads of overcurrent and usual current in the intelligent power IC used in the electric equipment of a vehicle. CONSTITUTION:A two-stage overcurrent detecting circuit 2 for the loads of overcurrent and usual current is incorporated in an intelligent power IC which has both the switching control for loads such as a head lamp, wiper motor and so on and the error detection thereof. When current starts to be supplied across the load, a current detection circuit 21 starts operation to turn on an output buffer 25 connected to an overcurrent detecting circuit 2 used in a high power load, whereby detecting the unusual state of overcurrent, such as rush current, which flows at the starting time of the load. After the specified time counted by a delay circuit 24, the output buffer 26 of the overcurrent detecting circuit 23 used for an usual current load is turned on so that the unusual state of usual current is detected. The response delay, the faulty operation and the malfunction due to the overcurrent control for loads may be dissolved.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an electronic power switch for automobiles, and in particular to an intelligent power IC for automobile electrical components suitable for electronic switches that switch loads such as lamps and motors.
Regarding.

[Conventional technology]

Conventional drive devices for controlling on/off of this type of automotive electrical equipment have used relays and the like. Furthermore, electronic devices have been used to control the on/off of loads using transistors, etc., as described in, for example, Japanese Unexamined Patent Publication No. 57-80946.

[Problem to be solved by the invention] The above-mentioned conventional technology only controls on/off of the load automobile electrical components, and does not take into consideration advanced control such as failure detection of the load, and does not meet the above-mentioned failure detection requirement. However, there was a problem in that sensors and detection circuits had to be created separately.

This problem can be solved by using an intelligent power IC for an electronic power switch for automobiles, which has been developed in recent years, because it has a built-in load failure detection circuit. However, the fault detection circuits of the intelligent power ICs that are currently under development do not take into consideration the inrush current that occurs when the power is turned on due to lamp loads, motor loads, etc., and the overcurrent detection circuit operates particularly when the above inrush current occurs. Therefore, sufficient current cannot be supplied to the lamp load, motor load, etc., resulting in problems such as delays in operation of the loads, malfunctions, and failure detection errors.

The purpose of the present invention is to solve the above-mentioned problems and provide an intelligent power IC for automobile electrical components that can perform advanced control such as load failure detection, and can easily control load current of lamps, motors, etc. even when the above-mentioned inrush current occurs. is to provide.

[Means to solve the problem]

The above purpose is to configure the load overcurrent detection circuit into a two-stage overcurrent detection circuit that performs two-stage overcurrent detection for load transient large current and steady current in an intelligent power IC that has a load switching control and failure detection circuit. , the two-stage overcurrent detection circuit includes, for example, a load current detection circuit, a delay circuit, a first overcurrent detection circuit for transient large current of the load, and a second overcurrent detection circuit for the steady current of the load. A certain period from when the current detection circuit detects the load current to when the delay circuit operates is defined as an inrush overcurrent detection period, and the period after the certain period is separated into a normal overcurrent detection period. This is achieved by an intelligent power IC for automotive electrical components, in which detection is performed by a first overcurrent detection circuit with a large detectable set current capacity and a second overcurrent detection circuit with a small detectable set current capacity, respectively. .

[For production]

In the above intelligent power IC for automotive electrical components,
For example, in the two-stage overcurrent detection circuit, the current detection circuit generates a gate-on signal that opens the gate of the overcurrent detection circuit when current starts flowing to the load, and opens the output gate of the first overcurrent detection circuit. The output signal of the first overcurrent detection circuit is enabled, and the gate-on signal passes through the delay circuit and opens the output gate of the second overcurrent detection circuit, so that the second overcurrent detection is performed after a certain period of delay. Since the output signal of the circuit is enabled, this makes the detection current capacity of the first overcurrent detection circuit larger than the detection current capacity of the second overcurrent detection circuit. As a result, this intelligent power IC can perform overcurrent detection in two stages, one for a certain period immediately after the current begins to flow, and the other for a period thereafter.As a result, this intelligent power IC can switch the load without malfunctioning even in the transient state of load current. and failure detection operations.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 7.

FIG. 2 is a system block diagram showing an embodiment of an intelligent power IC for automobile electrical components according to the present invention. In Figure 2, 1 is an intelligent power IC1
102 is a headlamp, 103 is a wiper motor, 104
is the headlamp switch, 105 is the wiper switch, 1
06 is a failure indicator, and 107 is a battery. The headlamp switch 104 in FIG. 2 controls the headlamp 102 via the intelligent power ICI, and the wiper switch 105 controls the wiper motor 103 via the intelligent power ICI. The intelligent power ICI also detects failures in the headlamp 102 and wiper motor 103, and displays the detection results on a failure indicator 106. Furthermore, the battery 107 is connected to the headlamp 102 via the intelligent power ICI.
and supplies power to the wiper motor 103.

FIG. 1 is a detailed block diagram of the intelligent power IC 1 shown in FIG. In Fig. 1, 2 is a two-stage overcurrent detection circuit, 3 is a temperature detection circuit, 4 is a no-load detection circuit, and 5 is a two-stage overcurrent detection circuit.
is a low voltage detection circuit, 6 is an AND gate circuit, 7 is a charge pump circuit, 8 is a gate overvoltage protection circuit, 9 is a NAND circuit for control output, 10 is a MOS FET, 11 is an overvoltage off switch, 12 is an inverter, 13 is the load, 1
4 is a microcomputer. The intelligent power ICI shown in Figure 1 includes a two-stage overcurrent detection circuit 2, a temperature detection circuit 3, a load detection circuit 4, a low voltage detection circuit 5, an AND gate circuit 6, and a charge and pump circuit with a rectification function. 7, a gate overvoltage protection circuit 8, a control output NAND circuit 9, a MOS FETl0, and an overvoltage off switch 11.

It is composed of an inverter 12.

FIG. 3 is a detailed block diagram of the two-stage overcurrent detection circuit 2 shown in FIG. In FIG. 3, 21 is a current detection circuit;
2 is overcurrent detection circuit I, 23 is overcurrent detection circuit ■, 24
2 is a delay circuit, 25 and 26 are output buffers, and 27 is an OR circuit for outputting a control signal. The two-stage overcurrent detection circuit 2 in FIG. 3 includes a current detection circuit 21, an overcurrent detection circuit 122,
It is composed of an overcurrent detection circuit 1123, a delay circuit 24, output buffers 25 and 26, and an OR circuit 27 for outputting a control signal. Note that the control signal output OR circuit 27 may be removed and outputs may be taken out from the output sofas 25 and 26, respectively.

Next, details of the operation of the intelligent power IC 1 having the above configuration will be explained. First, when an attempt is made to turn on the headlamp 102 by operating the headlamp switch 104 of the system shown in FIG. is input. Next, the output of the AND gate circuit 6 operates the MOS FET10 via the charge pump circuit 7 having a rectifying function, thereby lighting the headlamp 102 of the load 13.

Figure 4 shows the charge pump circuit 7 with the rectification function shown in Figure 1.
FIG. 2 is an input/output waveform diagram of In FIG. 4, 7a is an input voltage, 7b is an intermediate voltage, and 7C is an output voltage. The voltage V of the input voltage 7a of the output of the AND gate circuit 6 in FIG.
After the level of the O pulse is level-shifted to the voltage VH pulse of the intermediate voltage 7b, the DC voltage vH of the output voltage 7C is powered up and drives the MOS FET 10.

On the other hand, the control outputs of each failure (abnormality) detection circuit such as the two-stage overcurrent detection circuit 2, temperature detection circuit 3, no-load detection circuit 4, and low voltage detection circuit °5 are connected to the input of the AND gate circuit 6. When a failure is detected in even one of the above-mentioned failure (abnormality) detection circuits, the AND gate circuit 6 is turned off by its control output signal (inverted signal), and the output voltage is determined by the load output of the MOS FET 6. load 1
At the same time, the lighting operation of the headlamp 102 of No. 3 is stopped, the control output NAND circuit 9 is turned on, and the control output notifies the microcomputer 14 of a failure (abnormality), and the failure is displayed on the failure indicator 106 via the microcomputer 14. do.

At this time, the two-stage overcurrent detection circuit 2 detects 2 of the current of the load 13.
The temperature detection circuit 3 detects the temperature of MOSFETIO and sets the control output to "1" when the temperature is higher than the set temperature, and the no-load detection circuit 4 sets the control output to "1" at the time of detection. The unconnected (disconnected) state is detected and the control output is set to J#171, and the low voltage detection circuit 5 sets the control output to ``1'' when the voltage VB of the battery 107 is lower than the set voltage vL. On the other hand, the gate overvoltage protection circuit 8 is set to II when the voltage VB of the battery 107 is higher than the set voltage VH9.
I II and turns off the overvoltage off switch 11. Furthermore, when attempting to operate the wiper motor 103 by operating the wiper switch 105 of the system shown in FIG.
By the same operation as described above of the intelligent power ICI shown in the figure, on/off control of the wiper motor 103 of the load 13 and failure detection can be performed. Next, the function and operation of the two-stage overcurrent detection circuit 2 will be explained.

FIG. 5 is a load current characteristic diagram when the load 13 of FIG. 1 is connected. In FIG. 5, the intelligent power I
When the headlamp 102 or wiper motor 103 of the load 13 is connected to C1, the load 13 is connected to the MOS FET.
When the inrush current is turned on due to l0, a large current flows as shown by the solid line and the current ratio is 4 to 5 times higher than the rated current shown by the broken line. Shows current characteristics that allow the rated current to flow later.

FIG. 6 is a load voltage characteristic diagram when constant current control of the load 13 shown in FIG. 1 is performed. In FIG. 6, when the current is controlled as shown by the rated current characteristic A in FIG. 6 via the intelligent power ICI, the time it takes for the voltage of the load 13 to rise to the rated voltage of voltage ratio 1 shown by the broken line is, for example, as described above. Since there is a significant delay of about 10 times the time τ, operation delays or malfunctions of the load 13, erroneous failure indications on the failure indicator 106, etc. occur depending on the value of the limiting current.

Therefore, in the embodiment shown in FIG. 1, the above-mentioned problem is eliminated by adding a two-stage overcurrent detection circuit 2 whose detailed configuration is shown in FIG. 3.

The details of the operation of the above configuration shown in FIG. 3 will be explained.

The two-stage overcurrent detection circuit 2 in Fig. 3 is a MOS shown in Fig. 1.
When current starts to be supplied to the load 13, the current detection circuit 21 starts operating, and the output buffer 25 connected to the overcurrent detection circuit 122 is turned on. This overcurrent detection circuit 122 is set for detecting a large current, and operates when an abnormal rush current of the load 13 shown in FIG. 5 is detected.

On the other hand, the output of the current detection circuit 21 is connected to a delay circuit 24, which turns on the output buffer 26 connected to one of the overcurrent detection circuits 123 after a certain time T delay. Then, this overcurrent detection circuit [23 is set for normal current detection, and comes into operation when an abnormality in the rated current of the load 13 shown in FIG. 5 is detected.

FIG. 7 is an overcurrent detection characteristic diagram of the two-stage overcurrent detection circuit 2 of FIG. 3 (FIG. 1). In FIG. 7, if the constant delay time T set by the delay circuit 24 in FIG. 3 is set to be longer than the inrush current convergence time (time to reach the rated current) τ shown in FIG. The overcurrent detection characteristic of the detection circuit 2 shows a two-stage step-like characteristic, and the overcurrent detection circuit 12 exhibits a two-step step characteristic during a certain period of time T immediately after the load current is supplied to the headlamp 102 or the wiper motor 103 of the load 13.
2 becomes the large current detection mode ■, and after a certain time T, the overcurrent detection circuit changes to the normal current detection mode J mode by 23, which occurs only immediately after the current supply such as the rush current shown in Figure 5. It is possible to construct an intelligent power ICI that covers load current characteristics and eliminates response delays and malfunctions that occur when constant current control as shown in FIG. 6 is performed.

According to this embodiment, it is possible to realize a highly functional wire harness system that can easily and accurately perform on/off control of lamps, motor loads, etc. of automobile electrical components, and detect failures (abnormalities) of loads.

〔Effect of the invention〕

According to the present invention, by performing overcurrent detection of lamps, motor loads, etc. in two stages, it is possible to detect load-specific rising overcurrents such as inrush currents and detect overcurrents in a steady state, and there is a delay in response due to load overcurrent control. Since malfunctions and the like can be eliminated, it is possible to provide an intelligent power E-C for automobile electrical components that enables highly functional on/off control of loads and failure detection operations.

[Brief explanation of the drawing]

Fig. 1 is a detailed block diagram showing an embodiment of an intelligent power IC for automobile electrical components according to the present invention, Fig. 2 is a system block diagram as well, and Fig. 3 is a detailed block diagram of the two-stage overcurrent detection circuit shown in Fig. 1. Figure 4 is an input/output waveform diagram of the charge pump circuit shown in Figure 1, Figure 5 is a load current characteristic diagram when the load shown in Figure 1 is connected, and Figure 6 is a load current characteristic diagram when the load shown in Figure 1 is connected. Voltage characteristic diagram, Figure 7 is 2 of Figure 1 (Figure 3)
FIG. 3 is an overcurrent detection characteristic diagram of a stepwise overcurrent detection circuit. 1... Intelligent power IC, 2... 2-stage section 1st current detection circuit, 3° temperature detection circuit, 4° no load, detection circuit, 5... Low voltage detection circuit, 6...
Ant game circuit, 7% Yage Pop. Road, 8. /7'
-),'a Beautiful voltage protection circuit, 9... NAND circuit for control output, 10... MOS FET, 11... Overvoltage OFF switch, 12... Inverter, 13...
・Load, 14...Microcomputer, 21...Current detection circuit, 22...Overcurrent detection circuit I, 23...Overcurrent detection circuit ■, 24...Delay circuit, 25, 26... Output buffer, 27... OR circuit for control signal output, 102
...Headlamp, 103...Wiper motor. Representative Patent Attorney Masami Akimoto (-1---11---11＼ Part 3 Izugin Intersection 7 times

Claims (6)

[Claims] 1. In intelligent power ICs for automotive electrical components that are equipped with a load switching control circuit and a failure detection circuit, two-stage overcurrent detection is performed with two different detection current capacities for both transient large current and steady current of the load. An intelligent power IC for automotive electrical components, characterized by being equipped with a detection circuit. 2. 2. The intelligent power IC for automotive electrical equipment according to claim 1, wherein the load includes a lamp and a wiper motor. 3. The switching control circuit is characterized by comprising an AND gate circuit that inputs an external signal and the output signal of the failure detection circuit, a charge pump circuit that rectifies and amplifies the output, and a MOSFET whose gate is driven by the output. The intelligent power IC for automobile electrical components according to claim 1. 4. 2. The failure detection circuit includes the two-stage overcurrent detection circuit, the MOSFET temperature detection circuit, the load no-load detection circuit, and the battery voltage low voltage detection circuit. Intelligent power IC for automotive electrical components. 5. The vehicle according to claim 1, wherein the failure detection circuit includes a gate overvoltage protection circuit that detects an overvoltage of the battery voltage and turns off an overvoltage off switch to cut off application of the battery voltage to the MOSFET. Intelligent power IC for electrical components. 6. The two-stage overcurrent detection circuit described above includes a current detection circuit that detects the load current, a delay circuit that delays the output signal of the current detection circuit, and a first overcurrent detection circuit that has a larger detection current capacity and that detects overcurrent for large transient currents of the load. It includes a current detection circuit and a second overcurrent detection circuit with a smaller detection current capacity that performs overcurrent detection with respect to the steady current of the load, and the output signal of the first overcurrent detection circuit is determined by the output signal of the current detection circuit. 2. The intelligent power IC for automobile electrical components according to claim 1, wherein the output signal of the second overcurrent detection circuit is enabled by the output signal of the delay circuit.