JPH0720959A - Semiconductor device - Google Patents

Abstract

PURPOSE:To accurately discriminate the signal of a sensor, etc., and to make a device compact by forming a signal processing IC and a power IC on the same chip and precisely discriminating the signal of the sensor, etc. CONSTITUTION:The inside of the device consists of a constant voltage circuit 2 composed of a band-gap(B.G.) reference voltage 21, a comparator 3, a waveform shaping circuit 4, etc. The constant voltage circuit 2 is driven by a battery 5 for a vehicle and generates an output 30 determined by a B.G. reference voltage. This output 30 is much smaller than the battery voltage and even if variation of the battery voltage is very large, the output voltage 30 never drops, so that variation in threshold voltage is not caused. Further, the output 30 is connected directly to the threshold voltage input terminal of the comparator 3, so no division resistor is required and the need for trimming for the resistance is eliminated, and, the possibility that a noise due to a short connection is received, is eliminated and an extremely stable threshold voltage is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a semiconductor device used in a vehicle electronic circuit device, and more particularly to a semiconductor device requiring a reference voltage.

[0002]

2. Description of the Related Art Conventionally, electronic circuits such as microcomputers have been used in vehicles. Even though the vehicle is a noisy environment for electronic circuits, noise countermeasures are taken, and these devices are integrated circuits with the development of semiconductor devices and become compact devices that are used for controlling equipment. ing. In order to grasp the driving situation of the vehicle, the control operates the equipment based on the signals from multiple sensors according to the purpose.However, these sensor signals have recently become delicate signal level, and the electronic circuit Is also highly accurate.

Conventionally, for example, in the connection between the power supply circuit 34 and the sensor signal processing device 43 shown in FIG.
The functional portion of the semiconductor device 43 that processes the sensor signal is formed as an independent IC so that the reference voltage is obtained from the constant voltage line V _OM created in 1., and the power supply circuit 34 is connected independently. This is because conventionally, when the power supply circuit is simply formed together, the noise component that enters the input terminal adversely affects the power supply circuit and cannot be accurately detected. Therefore, the power supply of the semiconductor device 43 is driven based on the constant voltage V _OM generated by the power supply circuit 34 (36 in FIG. 3), and the threshold voltage determined by the two internal resistors 37 and 38 is used. In addition, waveform shaping of the input signal was performed.

[0004]

However, since the threshold voltage for determination of the sensor signal is based on the constant voltage V _OM , V _OM is a countermeasure against fluctuation when a large amount of current is consumed in other equipment. However, a voltage drop occurs, resulting in a change in the threshold voltage of the semiconductor device 43. If the threshold voltage changes, the level determination of the input signal will change delicately, and normal control will not be performed. Therefore, it is required to obtain more stable reference voltage and threshold voltage. In addition, since the sensor and the like are attached to distant parts, it is unavoidable that noise enters the long harness, and a normal sensor signal cannot be input to the input terminal of the electronic circuit device. Normally, the input terminal is at the same level as the ground in a no-signal state, and the sensor signal is often a positive voltage. However, depending on the condition of the vehicle, the ground level changes and a negative voltage is generated at the input terminal. Therefore, it is required to realize an integrated circuit capable of noise-resistant signal processing.

[0005]

In order to solve the above problems, the structure of the present invention is used in an electronic circuit device for a vehicle,
In a semiconductor device that processes a signal by providing a reference voltage or a threshold voltage by using a constant voltage of a constant voltage circuit, the constant voltage circuit is a power constant voltage circuit that is a voltage source of another element chip. Separately, the constant voltage circuit formed in the same chip of the semiconductor device is provided with a protection function against noise voltage added to the input terminal of the semiconductor device, and the reference voltage and the threshold voltage are directly It is provided by the output of a constant voltage circuit, and the constant voltage circuit is directly connected to a vehicle power source and driven. The configuration of the related invention is characterized in that the constant voltage circuit includes a temperature-compensated bandgap reference voltage circuit.

[0006]

The constant voltage generated in the power supply section in the chip is immediately connected to the functional element in the same chip as the reference voltage or the threshold voltage, or is divided and connected. Even if the vehicle power supply fluctuates considerably, the constant voltage circuit operates at a low voltage and generates a stable reference voltage and threshold voltage.

[0007]

Since the power supply section is formed in the same chip, the fluctuation of the constant voltage due to external noise is extremely reduced, and the performance of the functional element is improved. Further, since the constant voltage circuit can operate at a low voltage, it has a large noise margin with respect to the voltage fluctuation of the vehicle power supply.
Therefore, the circuit operation is stable and the reliability is improved. Since the power supply unit is integrated, the device becomes compact.

[0008]

EXAMPLES The present invention will be described below based on specific examples. FIG. 1 is a part of a block diagram of a semiconductor device 1 of a rotation signal waveform shaping circuit included in an electronic circuit device for a vehicle by way of example. Inside the semiconductor device 1, a bandgap reference voltage circuit (BG) 21 and the like are provided. The constant voltage circuit 2, the comparator 3, the waveform shaping circuit 4, and other functional circuits (not shown). The constant voltage circuit 2 is driven by the power source from the vehicle battery 5 and generates about 1.22 V determined by the bandgap reference voltage. As is well known, this voltage can maintain a constant value regardless of temperature changes. This voltage is input to one terminal of the comparator 3 and compared with the rotation signal from the rotation signal input terminal 8. The compared signals are made into a clear rectangular wave by the waveform shaping circuit 4, and the output terminal 9 outputs another signal processing integrated circuit (for example, CPU in FIG. 1) 10
Sent to. Further, in FIG. 1, the constant voltage of the constant voltage circuit 2 is controlled by a circuit (not shown) by the voltage V
_OM is generated, the battery voltage is controlled by the transistor 7, and constant voltage power is supplied to other circuits.

Although this voltage V _OM has a circuit for stabilization (not shown) (for example, RC circuit) and the like, it also causes a slight voltage fluctuation due to some load operation not shown. Therefore, conventionally, the threshold voltage is provided from this voltage, which is affected by the delicate sensor signal. Further, the switch 6 is turned on when the engine of the vehicle is started by the ignition switch, so that the power supply circuit supplies electric power. Conventionally, there is noise due to the on / off state of this switch, and the internal voltage V _OM also undergoes fluctuations, which affects the operation of devices connected to the power supply immediately after the on / off state.

The output 30 of a voltage of about 1.22 V generated by the bandgap reference voltage circuit 21 is different from the constant voltage V _OM of about 5 V which has been conventionally used, and the battery voltage of the vehicle is about 1 V.
It is sufficiently smaller than 2V, so when starting the engine,
Even if the battery voltage fluctuates considerably, the output voltage 30 does not drop and thus does not cause the voltage fluctuation of the reference voltage. Further, since the output 30 is directly connected to the threshold voltage input terminal of the comparator 3, there is no need for a dividing resistor and no trimming for that purpose. Since the connection line is shorter, there is no fear of receiving external noise, and a very stable threshold voltage can be obtained.

The bandgap reference voltage circuit 21 is a constant voltage generating circuit that uses the voltage value of the bandgap of the Si semiconductor transistor structure and has the structure shown in FIG. 5
Is stabilized, and the operation of the operational amplifier 28 compensates for the voltage difference based on the current difference between the transistors 26 and 27 having uniform characteristics to maintain the output 30 at a constant voltage. The base-emitter voltage of the transistors 26 and 27 changes depending on the temperature of the element, but the correction amount determined by the ratio of the resistors 24 and 25 makes the temperature characteristic flat, so that a constant output is obtained. To be

In the case of FIG. 1, the rotation signal comparator 3
Since the threshold voltage of is directly set to the output voltage value of the bandgap reference voltage circuit 21 to determine the rotation signal,
For example, in the case of a sensor signal for other purposes, the input signal needs to be adjusted so as to be discriminated by this threshold value, which can be easily realized by amplifying the input signal or lowering the voltage with a resistor. Or depending on the signal,
The output voltage value of the bandgap reference voltage circuit 21 may be increased by a highly accurate amplifier to be a reference voltage, or may be set to a low voltage by a dividing resistor.

As described above, the semiconductor device having the functional element and the power supply circuit are formed on the same chip and configured as in the present invention, whereby the signal of the sensor or the like can be accurately discriminated and the element of the voltage fluctuation can be eliminated. Therefore, accurate signal determination can be performed.
Further, by integrating the power supply and the signal processing IC, the device can be made compact.

[Brief description of drawings]

FIG. 1 is a block diagram of an integrated circuit that is an embodiment of the present invention in which a peripheral power source is integrated.

FIG. 2 is a circuit diagram of a bandgap reference voltage generation circuit.

FIG. 3 is a block diagram of an integrated circuit having a conventional configuration.

[Explanation of symbols]

1 semiconductor device (rotation signal waveform shaping circuit) 2 constant voltage circuit 3 comparator 4 waveform shaping circuit 5 vehicle battery 6 IG switch 7 transistor 8 rotation signal input terminal 9 signal output terminal 10 signal processing integrated circuit (eg CPU) 22 bias Supply circuits 23, 24, 25 Resistors 26, 27 Transistors with uniform characteristics 28 Operational amplifier 30 Output of constant voltage circuit (output of bandgap reference voltage circuit) 34 Power supply IC 37, 38 Resistance (divided resistance for reference voltage generation) 43 Semiconductor device (power supply circuit 34)

Claims (2)

[Claims] 1. A semiconductor device used in an electronic circuit device for a vehicle, wherein a constant voltage of a constant voltage circuit is used to provide a reference voltage and a threshold voltage to process a signal, wherein the constant voltage circuit is Is formed in the same chip of the semiconductor device separately from the power constant voltage circuit that serves as the voltage source of the element chip, and the constant voltage circuit has a protection function against noise voltage added to the input terminal of the semiconductor device. The semiconductor device, wherein the semiconductor device is characterized in that the reference voltage and the threshold voltage are directly given by an output of the constant voltage circuit, and the constant voltage circuit is directly connected to a vehicle power source to be driven. 2. The semiconductor device according to claim 1, wherein the constant voltage circuit includes a temperature-compensated bandgap reference voltage circuit.