JPH10155270A - Semiconductor device - Google Patents

Abstract

(57) Abstract: A switching noise generated by a charge pump circuit (13) is prevented from propagating to a semiconductor switch circuit (Q), and an electrolytic capacitor (C) is connected even when an inductive load (20) is connected. To avoid applying a drive waveform that exceeds the withstand voltage of the electrolytic capacitor C to the capacitor C. As a result, deterioration of various characteristics of the electrolytic capacitor C and dielectric breakdown are avoided. A power supply line for supplying power to a charge pump circuit and a power supply line for supplying power to a semiconductor switch circuit are separately provided. Ground potential GN
A filter 14 for removing switching noise is provided between Ds.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly, to a semiconductor switch circuit for supplying power to a load mounted on a vehicle, and a switching control of the semiconductor switch circuit to boost a power supply voltage to generate a boosted voltage. The present invention relates to a semiconductor device having a charge pump circuit for performing control.

More specifically, a power MOSFET and a power MOSFET as a semiconductor switch circuit for supplying power via a power supply line connected to a battery to a radio or a vehicle computer mounted on a vehicle such as an automobile.
A charge pump circuit for performing switching control (that is, ON control or OFF control) of T to increase the power supply voltage of the battery to generate a boosted voltage, and perform switching in response to a control signal from a vehicle computer The present invention relates to an intelligent power switch circuit (intelligent power module) that controls and selectively supplies a boosted voltage to each load.

[0003]

2. Description of the Related Art FIG. 2 is a circuit diagram for explaining a basic configuration of a conventional semiconductor device. FIG. 3 is a waveform diagram for explaining switching noise generated by the charge pump circuit.

Conventionally, as a semiconductor device of this type, for example, an intelligent power switch circuit 1 as shown in FIG. 2 has been disclosed.

[0005] Intelligent power switch circuit 1
Supplies power from a power supply line L connected to a battery 2 via a terminal P_1 to a load 3 such as a radio or a vehicle computer mounted on a vehicle such as an automobile via a terminal P_2 as shown in FIG. Power MOSFET Q as a semiconductor switch circuit to perform switching control (that is, ON / OFF control) of the power MOSFET Q, and a power supply voltage Vcc of the battery 2 connected between the terminal P_1 and the ground terminal P_3.
(Normally 12 Vdc) and a charge pump circuit 4 for executing control for generating a boosted voltage Vup.
A self-protection circuit 5 for executing control to inactivate and protect the power MOSFET Q when detecting an overcurrent state or an overheating state in the ETQ, and for notifying an overcurrent state or an overheating state generated in the power MOSFET Q to the outside; It had an abnormal signal forming circuit 6 for generating an abnormal signal.

The charge pump circuit 4 includes an oscillator for generating a timing pulse having a predetermined switching frequency and a MOS capacitor for receiving a charging current from the battery 2 and generating a boosted voltage Vup in synchronization with the timing pulse.

The self-protection circuit 5 includes a power MOSFET Q
A temperature detection circuit 5A that executes control to inactivate and protect the power MOSFET Q when an overheat condition is detected.
When the power MOSFET Q detects an overcurrent state, the power MOSFET Q has a current detection circuit 5B for inactivating and protecting the power MOSFET Q.

The abnormal signal forming circuit 6 includes a temperature detecting circuit 5A.
When the detected overheat state signal exceeds the predetermined voltage Vref1,
Alternatively, when the overcurrent state signal detected by the current detection circuit 5B exceeds the predetermined voltage Vref2, an abnormal signal is generated to notify the external vehicle computer (microcomputer 7) connected via the terminal P_4 of the fact. Logic function (specifically,
(A logic circuit including a comparator and a logic element OR).

The intelligent power switch circuit 1 is controlled by a switching control according to a control signal from a vehicle computer (microcomputer 7) connected via a terminal P_5 to selectively supply a boosted voltage to each load. Was running.

The vehicle computer (microcomputer 7) is connected to an abnormality display section 8 for displaying a message indicating that an overcurrent state or an overheat state has been detected in response to the abnormality signal.

Further, in such an intelligent power switch circuit 1, switching noise (see FIG. 3) is generated due to a timing pulse when the charge pump circuit 4 executes the boosting operation, and this switching noise is generated by the charge pump. As a result of being transmitted to the source S of the power MOSFET Q via the power supply line L of the circuit 4, there is a possibility that this switching noise will be transmitted to the load 3 via the drain D when the power MOSFET Q is activated. .

Therefore, in the conventional intelligent power switch circuit 1, a capacitor having a cutoff frequency characteristic corresponding to the frequency component of the switching noise is used as a low-pass filter in order to avoid such propagation of the switching noise to the load. 3 was provided in parallel.

When controlling the power supply for the power supply, the DC characteristics are regarded as important, so that the cutoff frequency fc is several [H].
z]. For the purpose of satisfying such a low cutoff frequency fc, an electrolytic capacitor having a large capacitance (specifically, several tens to several hundreds [μF]) has been used as the above-mentioned capacitor.

[0014]

However, in such a conventional intelligent power switch circuit,
In order to set the cutoff frequency fc to several Hz, an electrolytic capacitor C having a large capacitance is required. However, such an electrolytic capacitor C having a large capacitance has a withstand voltage of about 50 Vdc or less. Therefore, for example, inductive loads (for example, various motors and relays mounted on vehicles)
When the capacitor 3 is connected, a driving waveform exceeding the withstand voltage of the electrolytic capacitor C is applied to the electrolytic capacitor C. As a result, various characteristics of the electrolytic capacitor C are deteriorated, and furthermore, dielectric breakdown is caused. There was a technical problem that there was a possibility that it would not be possible.

An object of the present invention is to solve such a conventional problem. In particular, a power supply line for supplying power to a charge pump circuit and a power supply line for supplying power to a semiconductor switch circuit are separately provided. By providing a filter for removing switching noise between a power supply line for supplying power to the charge pump circuit and the ground potential, the switching noise generated by the charge pump circuit is prevented from propagating to the semiconductor switch circuit. In addition, even when an inductive load (for example, various motors or relays mounted on a vehicle) is connected, a driving waveform that exceeds the withstand voltage of the electrolytic capacitor is applied to the electrolytic capacitor. To avoid application of voltage, and as a result, deterioration of various characteristics of the electrolytic capacitor and dielectric breakdown It is an object of the present invention and.

[0016]

According to a first aspect of the present invention, there is provided a semiconductor switch circuit for supplying power to a load, and switching control of the semiconductor switch circuit to boost a power supply voltage Vcc to generate a boosted voltage Vup. In a semiconductor device having a charge pump circuit to be executed, a power supply line L for supplying power to the charge pump circuit 13 and a power supply line L for supplying power to the semiconductor switch circuit Q are separately provided, so that the charge pump Circuit 13
The semiconductor device 10 is configured so as to prevent noise related to switching control that causes the above from being propagated to the semiconductor switch circuit Q.

According to the first aspect of the present invention, the charge pump circuit 13 and the semiconductor switch circuit Q can be electrically isolated from each other.
The switching noise generated by the power supply line L can be prevented from propagating to the semiconductor switch circuit Q via the power supply line L.

According to a second aspect of the present invention, in the semiconductor device 10 according to the first aspect, the charge pump circuit 1
Filter 1 for removing the switching noise between a power supply line L for supplying power to the power supply line 3 and a ground potential GND.
4 is provided.

According to the invention described in claim 2, according to claim 1
In addition to the effects described in (1), the charge pump circuit 13 and the semiconductor switch circuit Q can be electrically isolated by using the filter 14, so that the charge pump circuit 1
3 can be prevented from being transmitted to the semiconductor switch circuit Q via the power supply line L.

According to a third aspect of the present invention, in the semiconductor device 10 according to the second aspect, the filter 14 is a low-pass filter 14 having a cutoff frequency fc characteristic corresponding to a frequency component of the switching noise. The semiconductor device 10 is characterized in that:

According to the invention of claim 3, according to claim 2,
In addition to the effects described in (1), the switching noise having a frequency component equal to or higher than the cutoff frequency fc can be cut off using the low-pass filter 14 to electrically isolate the charge pump circuit 13 and the semiconductor switch circuit Q. As a result, it is possible to prevent the switching noise generated by the charge pump circuit 13 from being transmitted to the semiconductor switch circuit Q via the power supply line L.

According to a fourth aspect of the present invention, in the semiconductor device of the third aspect, the semiconductor switch circuit
The semiconductor switch circuit Q
A semiconductor device 10 having a self-protection circuit 15 for executing control for inactivating and protecting the semiconductor device.

According to the invention described in claim 4, according to claim 3,
In addition to the effects described in (1), switching noise having a frequency component equal to or higher than the cutoff frequency fc can be cut off by using the low-pass filter 14, so that the charge pump circuit 13 and the semiconductor switch circuit Q are electrically connected. The isolated state can be achieved, and the malfunction of the self-protection circuit 15 due to the switching noise can be avoided, and the overcurrent state of the semiconductor switch circuit Q can be accurately detected.

The invention described in claim 5 is the invention according to claim 3 or 4
Wherein the semiconductor switch circuit Q includes a self-protection circuit 15 that executes control for inactivating and protecting the semiconductor switch circuit Q when detecting an overheating state of the semiconductor switch circuit Q. The semiconductor device 10.

According to the invention described in claim 5, according to claim 3,
Or in addition to the effect described in 4, the switching noise having a frequency component equal to or higher than the cutoff frequency fc can be cut off by using the low-pass filter 14, so that the charge pump circuit 13 and the semiconductor switch circuit Q are electrically connected. It is possible to prevent the self-protection circuit 15 from malfunctioning due to switching noise.
There is an effect that the overheating state of the semiconductor switch circuit Q can be accurately detected.

The invention described in claim 6 is the invention according to claims 3 to 5
The semiconductor device 10 according to any one of the above, further comprising an abnormal signal forming circuit 16 that generates an abnormal signal 16a for notifying an overcurrent state generated in the semiconductor switch circuit Q to the outside. The semiconductor device 10.

According to the invention of claim 6, according to claim 3,
6. In addition to the effects described in any one of the above items 5, the switching noise having a frequency component equal to or higher than the cutoff frequency fc can be cut off by using the low-pass filter 14, so that the charge pump circuit 13 and the semiconductor switch A state in which the circuit Q is electrically isolated can be avoided, a malfunction of the abnormal signal forming circuit 16 caused by switching noise can be avoided, and an overcurrent state of the semiconductor switch circuit Q can be accurately reported. It works.

[0028] The invention according to claim 7 is the invention according to claims 3 to 6.
11. The semiconductor device according to claim 1, further comprising: an abnormal signal forming circuit 16 that generates an abnormal signal 16a for notifying an overheating state generated in the semiconductor switch circuit Q to the outside. The device 10.

According to the invention described in claim 7, according to claim 3,
7. In addition to the effects described in any one of the above items 6, the switching noise having a frequency component equal to or higher than the cutoff frequency fc can be cut off by using the low-pass filter 14, so that the charge pump circuit 13 and the semiconductor switch The circuit Q can be electrically isolated, the malfunction of the abnormal signal forming circuit 16 caused by switching noise can be avoided, and the overheating state of the semiconductor switch circuit Q can be accurately reported. To play.

According to an eighth aspect of the present invention, in the semiconductor device 10 according to the seventh aspect, the semiconductor switch circuit Q
Has an n-channel power MOSFET Q, and the source S of the n-channel power MOSFET Q
cc, and a load 2 is connected between the drain D and the ground potential GND.
0 is connectable, the semiconductor device 10
It is.

According to the invention of claim 8, according to claim 7,
In addition to the effects described in (1), switching noise having a frequency component equal to or higher than the cut-off frequency fc is cut off by using the low-pass filter 14 so that the charge pump circuit 13 and n
As a result of being able to electrically isolate the channel power MOSFET Q, the switching noise generated by the charge pump circuit 13 can be prevented from propagating to the n-channel power MOSFET Q via the power supply line L. It works.

The invention according to claim 9 is the invention according to claims 2 to 8
In the semiconductor device 10 according to any one of the above, a power supply line L that supplies power to the charge pump circuit 13.
Are connected to the source S via the filter 14.

According to the ninth aspect of the present invention, a second aspect is provided.
9. In addition to the effects described in any one of the above items 8, the switching noise having a frequency component equal to or higher than the cutoff frequency fc invading the source S of the n-channel power MOSFET Q is cut off using the low-pass filter 14 and charged. Pump circuit 13 and n-channel power MOSFET
As a result, the switching noise generated by the charge pump circuit 13 can be prevented from propagating from the source S to the n-channel power MOSFET Q.

According to a tenth aspect of the present invention, in the semiconductor device of the ninth aspect, the semiconductor device is connected to a ground terminal P_1 for applying a ground potential GND to a circuit and a power supply section for generating the power supply voltage Vcc. A first power supply input terminal P_2 for connecting the power supply line L connected to the source S of the n-channel power MOSFET Q;
A second power supply input terminal P_3 for connecting the power supply line L to the power supply voltage input end of the power supply line L;
The semiconductor device 10, comprising: a power output terminal P_4 for connecting the drain D of the OSFET Q to the external load 20; and an abnormal signal 16a output terminal P_5 for outputting the abnormal signal 16a to the outside. is there.

According to the tenth aspect, the same effect as the ninth aspect can be obtained.

According to an eleventh aspect of the present invention, in the semiconductor device of the tenth aspect, a Zener diode Dz for preventing overvoltage is provided in parallel with the capacitor C in the low-pass filter 14. Semiconductor device 10.

According to the eleventh aspect of the present invention, in addition to the effect of the tenth aspect, by providing a Zener diode Dz for preventing overvoltage in parallel with the capacitor C, the inductive load 20 ( For example, even when various motors and relays mounted on a vehicle are connected, it is possible to prevent a drive waveform that exceeds the breakdown voltage of the electrolytic capacitor C from being applied to the electrolytic capacitor C, and as a result, This has the effect that deterioration of various characteristics of the electrolytic capacitor C and dielectric breakdown can be avoided.

A twelfth aspect of the present invention is the semiconductor device 10 according to the eleventh aspect, wherein the cutoff frequency fc is a frequency of a broadcast wave.

According to the twelfth aspect of the present invention, in addition to the effect of the eleventh aspect, even when a load 20 such as a radio using the frequency of a broadcast radio wave is connected, Switching noise that has propagated through the power supply line L can be cut off using the electrolytic capacitor C. As a result, it is possible to prevent noise from entering or malfunctioning during operation of the load 20 such as a radio. This has the effect that it can be avoided.

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment will be described below with reference to the drawings.

FIG. 1 is a circuit diagram for explaining a basic configuration of a semiconductor device 10 according to the present invention.

The semiconductor device 10 includes a power MOSFET as a semiconductor switch circuit Q for supplying power to a load 20 such as a radio or a vehicle computer mounted on a vehicle such as an automobile via a power line L connected to a battery. And the power MOSFET are subjected to switching control (that is, ON control or OFF control), and the power supply voltage Vcc of the battery (normally, 12 [Vdc]) is boosted to, for example, 25 [Vdc].
A charge pump circuit 13 for executing control for generating a boosted voltage Vup of about the same level, and executing switching control in response to a boosted control signal from a vehicle computer to selectively supply the boosted voltage Vup to each load 20. It is a device to do.

The vehicle computer includes an air conditioner computer, a cruise control computer, and a traction control (TRC) mounted on the vehicle.
Computer, anti-lock brake (ABS) computer, navigation computer, engine control computer, etc.

The first feature of the semiconductor device 10 is that, as shown in FIG.
(Intelligent power module), a filter 14 suitable for a connection form externally connected to the intelligent power switch circuit 22, a diode for preventing reverse connection of the battery 18, a resistance element R2, and the like.

A second feature of the semiconductor device 10 is that, as shown in FIG. 1, a charge pump circuit 13 is provided with a charge pump circuit 13 for preventing noise relating to switching control generated from the charge pump circuit 13 from propagating to a semiconductor switch circuit Q. 13 is provided separately from the power supply line L for supplying power to the semiconductor switch circuit Q.

As a result, the charge pump circuit 13 and the semiconductor switch circuit Q can be electrically isolated from each other. As a result, switching noise generated by the charge pump circuit 13 is reduced via the power supply line L to the semiconductor switch circuit Q. To be prevented from being propagated.

The third characteristic of the semiconductor device 10 is as follows.
Power supply line L for supplying power to charge pump circuit 13
And a filter 14 for removing switching noise between the power supply and the ground potential GND.

The provision of the filter 14 allows the charge pump circuit 13 and the semiconductor switch circuit Q to be electrically isolated from each other using the filter 14. As a result, the switching noise generated by the charge pump circuit 13 is reduced by the power supply. This has the effect of preventing propagation to the semiconductor switch circuit Q via the line L.

The present filter 14 is a low-pass filter 14 having a cutoff frequency fc characteristic corresponding to the frequency component of the switching noise. The low-pass filter 14 includes a resistance element R1 and an electrolytic capacitor C, as shown in FIG.

The electrolytic capacitor C has a cut-off frequency fc of several [Hz] because direct current characteristics are emphasized when controlling power supply for a power supply. In order to satisfy such a low cutoff frequency fc, several tens to ten
It is desirable to use an electrolytic capacitor having a large capacitance of about 0 [μF].

By providing such a low-pass filter 14, switching noise having a frequency component equal to or higher than the cutoff frequency fc can be reduced.
, The charge pump circuit 13 and the semiconductor switch circuit Q can be electrically isolated from each other. As a result, switching noise generated by the charge pump circuit 13 is applied to the semiconductor switch circuit Q via the power supply line L. This has the effect that propagation can be prevented.

In the present embodiment, the cutoff frequency fc
Is set to the frequency of the broadcast radio wave.

According to this, even when a load 20 such as a radio using the frequency of a broadcast radio wave is connected, the switching noise transmitted through the power supply line L can be cut off using the electrolytic capacitor C. As a result, it is possible to prevent the noise and the malfunction from being mixed during the operation of the load 20 such as a radio.

Further, a Zener diode Dz for preventing an overvoltage is provided in parallel with the electrolytic capacitor C in the low-pass filter 14. It is desirable that the Zener voltage of the Zener diode Dz be equal to or lower than the withstand voltage of the electrolytic capacitor C.

By providing a zener diode Dz for preventing overvoltage in parallel with the electrolytic capacitor C, even when an inductive load 20 (for example, various motors or relays mounted on a vehicle) is connected, It is possible to prevent a drive waveform that exceeds the breakdown voltage of the electrolytic capacitor C from being applied to the electrolytic capacitor C, and as a result, it is possible to avoid deterioration of various characteristics of the electrolytic capacitor C and dielectric breakdown. .

Next, an embodiment of the intelligent power switch circuit 22 will be described with reference to the drawings.

The intelligent power switch circuit 22
Supplies power from a power supply line L connected to a battery 18 via a terminal P_2 to a load 20 such as a radio or a vehicle computer mounted on a vehicle such as an automobile via a terminal P_4, as shown in FIG. Control of the n-channel power MOSFET Q and the n-channel power MOSFET Q as the semiconductor switch circuit Q to be switched (that is, ON / OF)
F control), a charge pump circuit 13 for executing control for increasing the power supply voltage Vcc (normally 12 Vdc) of the battery 18 connected between the terminal P_3 and the ground terminal P_1 to generate a boosted voltage Vup, and an n-channel power MOSFET Q A self-protection circuit 15 for executing control to inactivate and protect the n-channel power MOSFET Q when an overcurrent state or an overheat state is detected.
And an abnormal signal forming circuit 16 for generating an abnormal signal 16a for notifying an overcurrent state or an overheat state occurring to the outside.

As shown in FIG. 1, the intelligent power switch circuit 22 is connected to the ground potential GN.
A power supply line L connected to a power supply unit 18 for generating a power supply voltage Vcc, a first power supply input terminal P_2 for connecting a source S of the n-channel power MOSFET Q, and a charge pump. A second power supply input terminal P_3 for connecting the power supply voltage input terminal of the circuit 13 to the power supply line L; a power supply output terminal for connecting the drain D of the n-channel power MOSFET Q to the external vehicle computer 23 and the load 20; P_4 and an abnormal signal output terminal P_5 for outputting the abnormal signal 16a to the outside.

The charge pump circuit 13 receives a charging current from the battery 18 in synchronization with an oscillator for generating a timing pulse of a predetermined switching frequency (specifically, 90 [kHz]) and a boosted voltage V
A MOS capacitor for generating up is built in.

The semiconductor switch circuit Q has an n-channel power MOSFET Q. n-channel power MOS
In the FET Q, an n-channel power MOSFET Q
Is connected to the power supply voltage Vcc, the gate is connected to the tri-state gate controlled by the charge pump circuit 13, and the load 20 can be connected between the drain D and the ground potential GND.

Accordingly, the switching noise having a frequency component equal to or higher than the cutoff frequency fc is cut off by using the low-pass filter 14, and the charge pump circuit 13 and the n-channel power MOSFET Q can be electrically isolated. As a result, it is possible to prevent the switching noise generated by the charge pump circuit 13 from being transmitted to the n-channel power MOSFET Q via the power supply line L.

At this time, the power supply line L for supplying power to the charge pump circuit 13 is connected to the source S via the filter 14.

According to such a connection form, the switching noise having a frequency component equal to or higher than the cutoff frequency fc invading the source S of the n-channel power MOSFET Q is cut off by using the low-pass filter 14 and the charge pump circuit 13 is cut off. As a result of being able to electrically isolate the n-channel power MOSFET Q, it is possible to prevent the switching noise generated by the charge pump circuit 13 from propagating from the source S to the n-channel power MOSFET Q. Play.

The self-protection circuit 15 has an n-channel power M
When the OSFET Q detects an overcurrent state, it has a current detection circuit 151 for executing control for inactivating and protecting the n-channel power MOSFET Q.

By providing such a current detection circuit 151, switching noise having a frequency component equal to or higher than the cutoff frequency fc can be cut off using the low-pass filter 14, so that the charge pump circuit 13 and the semiconductor This makes it possible to electrically isolate the switch circuit Q from the switch circuit Q, thereby avoiding a malfunction of the self-protection circuit 15 caused by switching noise.
The overcurrent state can be accurately detected.

Further, the self-protection circuit 15 has a temperature detection circuit 152 for executing control to inactivate and protect the n-channel power MOSFET Q when an overheat state is detected in the n-channel power MOSFET Q.

By providing such a function, switching noise having a frequency component equal to or higher than the cutoff frequency fc can be cut off by using the low-pass filter 14, so that the charge pump circuit 13 and the semiconductor switch circuit Q Are electrically isolated from each other, so that a malfunction of the self-protection circuit 15 due to switching noise can be avoided, and an overheated state of the semiconductor switch circuit Q can be accurately detected.

The abnormal signal forming circuit 16 includes the temperature detecting circuit 1
When the overheat state signal detected by 52 exceeds the predetermined voltage Vref1, or when the overcurrent state signal detected by the current detection circuit 151 exceeds the predetermined voltage Vref2, an external vehicle computer connected via the terminal P_5 23 has a logic circuit (specifically, a logic circuit composed of a comparator, a logic element OR, or the like) for generating an abnormal signal 16a for notifying the user.

By providing such a function, switching noise having a frequency component equal to or higher than the cutoff frequency fc can be cut off by using the low-pass filter 14, so that the charge pump circuit 13 and the semiconductor switch circuit Q Can be electrically isolated from each other, and the abnormal signal forming circuit 1 caused by switching noise can be provided.
6 can be avoided, and an overcurrent state of the semiconductor switch circuit Q can be accurately reported.

Further, the abnormal signal forming circuit 16 has a function of generating an abnormal signal 16a for notifying an overheating state generated in the semiconductor switch circuit Q to the outside.

By providing such a function, switching noise having a frequency component equal to or higher than the cutoff frequency fc can be cut off by using the low-pass filter 14, so that the charge pump circuit 13 and the semiconductor switch circuit Q Can be electrically isolated from each other, and the abnormal signal forming circuit 1 caused by switching noise can be provided.
6 can be avoided, and the overheating state of the semiconductor switch circuit Q can be accurately notified.

The vehicle computer 23 is connected to the intelligent power switch circuit 22 connected via the terminal P_6.
Has a function of giving a control signal to the CPU and prompting execution of switching control. Further, it is desirable that the vehicle computer 23 is connected to an abnormality display section 24 for displaying a message indicating that an overcurrent state or an overheat state has been detected in response to the abnormality signal 16a.

As described above, according to the first embodiment, the switching noise (FIG. 3) caused by the timing pulse when the charge pump circuit 13 executes the boosting operation.
And the switching noise is propagated to the source S of the n-channel power MOSFET Q via the power supply line L of the charge pump circuit 13, the switching noise is reduced by the effect of the low-pass filter 14 to the ground potential GND. Is bypassed to the side
Even when the channel power MOSFET Q is activated, there is no possibility that the switching noise is transmitted to the load 20 via the drain D.

Therefore, it is not necessary to provide a capacitor C having a cutoff frequency fc characteristic according to the frequency component of the switching noise as the low-pass filter 14 in parallel with the load 20.

Further, even when an inductive load 20 such as a motor or a relay is connected to the semiconductor device 10 using a large-capacity electrolytic capacitor C having a withstand voltage of about 50 [Vdc] or less. By the effect of the Zener diode Dz, it is possible to prevent a drive waveform that exceeds the breakdown voltage of the electrolytic capacitor C from being applied to the electrolytic capacitor C. As a result, it is possible to avoid the possibility that the various characteristics of the electrolytic capacitor C are deteriorated or the dielectric capacitor is not functioned due to dielectric breakdown.

[0076]

According to the first aspect of the present invention, the charge pump circuit 13 and the semiconductor switch circuit Q can be electrically isolated from each other.
3 can be prevented from being transmitted to the semiconductor switch circuit Q via the power supply line L.

According to the invention of claim 2, according to claim 1,
In addition to the effects described in (1), the charge pump circuit 13 and the semiconductor switch circuit Q can be electrically isolated by using the filter 14, so that the charge pump circuit 1
3 can be prevented from being transmitted to the semiconductor switch circuit Q via the power supply line L.

According to the invention described in claim 3, according to claim 2
In addition to the effects described in (1), the switching noise having a frequency component equal to or higher than the cutoff frequency fc can be cut off using the low-pass filter 14 to electrically isolate the charge pump circuit 13 and the semiconductor switch circuit Q. As a result, it is possible to prevent the switching noise generated by the charge pump circuit 13 from being transmitted to the semiconductor switch circuit Q via the power supply line L.

According to the invention described in claim 4, according to claim 3,
In addition to the effects described in (1), switching noise having a frequency component equal to or higher than the cutoff frequency fc can be cut off by using the low-pass filter 14, so that the charge pump circuit 13 and the semiconductor switch circuit Q are electrically connected. The isolated state can be achieved, and the malfunction of the self-protection circuit 15 due to the switching noise can be avoided, and the overcurrent state of the semiconductor switch circuit Q can be accurately detected.

According to the invention described in claim 5, according to claim 3,
Or in addition to the effect described in 4, the switching noise having a frequency component equal to or higher than the cutoff frequency fc can be cut off by using the low-pass filter 14, so that the charge pump circuit 13 and the semiconductor switch circuit Q are electrically connected. It is possible to prevent the self-protection circuit 15 from malfunctioning due to switching noise.
There is an effect that the overheating state of the semiconductor switch circuit Q can be accurately detected.

According to the invention described in claim 6, according to claim 3,
6. In addition to the effects described in any one of the above items 5, the switching noise having a frequency component equal to or higher than the cutoff frequency fc can be cut off by using the low-pass filter 14, so that the charge pump circuit 13 and the semiconductor switch A state in which the circuit Q is electrically isolated can be avoided, a malfunction of the abnormal signal forming circuit 16 caused by switching noise can be avoided, and an overcurrent state of the semiconductor switch circuit Q can be accurately reported. It works.

According to the invention of claim 7, according to claim 3,
7. In addition to the effects described in any one of the above items 6, the switching noise having a frequency component equal to or higher than the cutoff frequency fc can be cut off by using the low-pass filter 14, so that the charge pump circuit 13 and the semiconductor switch The circuit Q can be electrically isolated, the malfunction of the abnormal signal forming circuit 16 caused by switching noise can be avoided, and the overheating state of the semiconductor switch circuit Q can be accurately reported. To play.

According to the invention of claim 8, according to claim 7,
In addition to the effects described in (1), switching noise having a frequency component equal to or higher than the cut-off frequency fc is cut off by using the low-pass filter 14 so that the charge pump circuit 13 and n
As a result of being able to electrically isolate the channel power MOSFET Q, the switching noise generated by the charge pump circuit 13 can be prevented from propagating to the n-channel power MOSFET Q via the power supply line L. It works.

According to the ninth aspect of the present invention, there is provided a second aspect.
9. In addition to the effects described in any one of the above items 8, the switching noise having a frequency component equal to or higher than the cutoff frequency fc invading the source S of the n-channel power MOSFET Q is cut off using the low-pass filter 14 and charged. Pump circuit 13 and n-channel power MOSFET
As a result, the switching noise generated by the charge pump circuit 13 can be prevented from propagating from the source S to the n-channel power MOSFET Q.

According to the tenth aspect, the same effect as the ninth aspect can be obtained.

According to the eleventh aspect of the present invention, in addition to the effect of the tenth aspect, by providing a Zener diode Dz for preventing overvoltage in parallel with the capacitor C, the inductive load 20 ( For example, even when various motors and relays mounted on a vehicle are connected, it is possible to prevent a drive waveform that exceeds the breakdown voltage of the electrolytic capacitor C from being applied to the electrolytic capacitor C, and as a result, This has the effect that deterioration of various characteristics of the electrolytic capacitor C and dielectric breakdown can be avoided.

According to the twelfth aspect of the invention, in addition to the effect of the eleventh aspect, even when a load 20 such as a radio using the frequency of a broadcast radio wave is connected, Switching noise that has propagated through the power supply line L can be cut off using the electrolytic capacitor C. As a result, it is possible to prevent noise from entering or malfunctioning during operation of the load 20 such as a radio. This has the effect that it can be avoided.

[Brief description of the drawings]

FIG. 1 is a circuit diagram for explaining a basic configuration of a semiconductor device of the present invention.

FIG. 2 is a circuit diagram illustrating a basic configuration of a conventional semiconductor device.

FIG. 3 is a waveform diagram for explaining switching noise generated by a charge pump circuit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Semiconductor device 13 Charge pump circuit 14 Filter (low-pass filter) 15 Self-protection circuit 16 Abnormal signal formation circuit 16a Abnormal signal 18 Power supply unit 20 Load C Capacitor D Drain Dz Zener diode fc Cut-off frequency GND Ground potential L Power line P_1 Ground terminal P_2 First power input terminal P_3 Second power input terminal P_4 Power output terminal P_5 Abnormal signal output terminal Q Semiconductor switch circuit (n-channel power MOS
FET) S source Vcc Power supply voltage vup Boost voltage

Claims (12)

[Claims] 1. A semiconductor device comprising: a semiconductor switch circuit for supplying power to a load; and a charge pump circuit for performing switching control of the semiconductor switch circuit to boost a power supply voltage to generate a boosted voltage. By separately providing a power supply line for supplying power to the semiconductor switch circuit and a power supply line for supplying power to the semiconductor switch circuit, it is possible to prevent noise related to switching control generated by the charge pump circuit from propagating to the semiconductor switch circuit. A semiconductor device, wherein the semiconductor device is configured to prevent such a situation. 2. The semiconductor device according to claim 1, wherein a filter for removing the switching noise is provided between a power supply line for supplying power to the charge pump circuit and a ground potential. 3. The semiconductor device according to claim 2, wherein the filter is a low-pass filter having a cutoff frequency characteristic according to a frequency component of the switching noise. 4. The semiconductor device according to claim 3, further comprising: a self-protection circuit that executes control for inactivating and protecting the semiconductor switch circuit when an overcurrent state is detected in the semiconductor switch circuit. Semiconductor device. 5. The semiconductor device according to claim 3, further comprising: a self-protection circuit that executes control for inactivating and protecting the semiconductor switch circuit when detecting an overheating state in the semiconductor switch circuit. 13. The semiconductor device according to claim 1. 6. The semiconductor device according to claim 3, further comprising: an abnormal signal forming circuit that generates an abnormal signal for notifying an overcurrent state generated in the semiconductor switch circuit to the outside. 13. The semiconductor device according to claim 1. 7. The semiconductor device according to claim 3, further comprising an abnormal signal forming circuit for generating an abnormal signal for notifying an overheating state generated in the semiconductor switch circuit to the outside. Semiconductor device. 8. The semiconductor switch circuit has an n-channel power MOSFET, a source of the n-channel power MOSFET is connected to the power supply voltage, and a load can be connected between a drain and a ground potential. The semiconductor device according to claim 7, wherein: 9. The semiconductor according to claim 2, wherein a power supply line for supplying power to the charge pump circuit is connected to the source via the filter. apparatus. 10. A ground terminal for applying a ground potential to a circuit, a first power input terminal for connecting a power line connected to a power unit for generating the power voltage and a source of the n-channel power MOSFET. A second power supply input terminal for connecting a power supply voltage input terminal of the charge pump circuit to the power supply line; a power supply output terminal for connecting a drain of the n-channel power MOSFET to an external load; The semiconductor device according to claim 9, further comprising: an abnormal signal output terminal for outputting the abnormal signal to the outside. 11. The semiconductor device according to claim 10, wherein a Zener diode for preventing overvoltage is provided in parallel with the capacitor in the low-pass filter. 12. The semiconductor device according to claim 11, wherein the cutoff frequency is a frequency of a broadcast radio wave.