JP2000299630A - Semiconductor device - Google Patents

Abstract

(57) [Problem] To provide a semiconductor device that does not require a shunt resistor and that can respond to an abnormal current when an incomplete short circuit occurs and that can respond at high speed to a high voltage condition. SOLUTION: First and second semiconductor elements QA and QB
And a comparator CMP1 for comparing the voltages of the first and second semiconductor elements QA and QB, and a first semiconductor element QA and a second semiconductor element QB according to the output of the comparator CMP1.
Drive circuit 11 for supplying a control voltage to each control electrode
1 and a resistor R2 between the first input terminal and the lower power supply terminal _NL.
8, a first diode D21 connected through
, And a second diode D22 connected between the low-level power supply terminal _NL . When an abnormal current occurs, the first semiconductor element QA is turned on / off.
Off control generates a current oscillation, and by this current oscillation,
Blocking an external input terminal T ₁ of the conductive state between the first external output terminal T _3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device, and more particularly to a semiconductor device suitable for a high-voltage power supply control device.

[0002]

2. Description of the Related Art As a semiconductor device (power semiconductor device) used in a conventional power supply control device, there is, for example, one shown in FIG. The power supply control device shown in FIG. 5 is a device that selectively supplies power from a battery to each load in an automobile and controls power supply to the load by the main semiconductor element QA. The main semiconductor element QA is a transistor QA with a built-in temperature sensor. The drain terminal D of the main semiconductor element QAQA is connected to a power supply 101 that supplies the output voltage VB, and the load 1 is connected to the source terminal SA of the main semiconductor element QA.
02 is connected. Here, as the load 102,
Loads used in automobiles, such as automobile headlights, taillights, wiper motors, and power window motors, are applicable.

The power supply shown in FIG. 5 has an overcurrent detection / protection function. The main semiconductor element QA has a terminal T _S
The load 102 is connected via the. Further, a reference semiconductor element (reference MOS transistor) QB is connected in parallel with the main semiconductor element QA.
Via the terminal T _R the resistor Rr is connected. In the circuit configuration shown in FIG. 5, the voltage between the drain and source of the main semiconductor element QA, which is generated when a load current flows through the main semiconductor element QA, and the voltage between the drain and source of the reference semiconductor element QB determined by the resistance Rr are compared. It is constantly checked whether or not an overcurrent exceeding a preset overcurrent determination value has flowed by comparison in the device CMP1. When an overcurrent flows, the driving circuit 111
To turn on / off the main semiconductor element QA and the reference semiconductor element QB, and shut off the main semiconductor element QA when the on / off operation continues for a certain period of time. Thus, the wiring and the semiconductor device are prevented from being damaged by overcurrent.

The power supply shown in FIG. 5 will be described in detail below. The main semiconductor element QA and the reference semiconductor element QB are configured by connecting a plurality of unit elements each formed of an nMOS transistor having the same characteristics and structure in parallel. Main semiconductor element QA and reference semiconductor element QB
Let N1 and N2 be the numbers of unit elements of
The configuration is such that 1≫N2. In this example, N1: N2
= 1000: 1. The drain electrode D of the main semiconductor element QA and the drain electrode DB of the reference semiconductor element QB are connected to each other, and the gate electrodes are also connected to each other. Between the source SB of the reference semiconductor element QB and the ground potential GND,
Via the terminal T _R, the resistor Rr is connected. Resistance R
A constant current circuit or a circuit in which a constant current circuit and a resistor are connected in parallel may be connected instead of r. FIG. 5 illustrates an example in which the resistor Rr is connected.

The circuits enclosed by the dotted line in FIG. 5 are usually integrated on the same semiconductor chip 110 and monolithically integrated as a power IC. Semiconductor chip 1
A switch SW1 having one end connected to the resistor R10 and the other end connected to the ground potential GND is provided outside the resistor R10.
Is connected to a power supply VB. The potential at the connection point between the resistor R10 and the switch SW1 is applied to the drive circuit 111 inside the semiconductor chip 110 via the terminal _TG ,
When W1 is turned on, the drive circuit 111 applies a voltage VP boosted by a charge pump circuit (not shown) to the gates of the main semiconductor element QA and the reference semiconductor element QB to turn on the main semiconductor element QA and the reference semiconductor element QB. . For example, when the power supply voltage is VB, VP = VB + 10V.

The on-resistance per unit element of the MOS transistor constituting the main semiconductor element QA and the reference semiconductor element QB is R _fet, and the on-resistances of the main semiconductor element QA and the reference semiconductor element QB are R _onA and R _onB , respectively.
If the main semiconductor element QA and the reference semiconductor element QB are completely turned on, that is, in the ohmic region, R _onA = R _fet / N1 (1) R _onB = R _fet / N2 (2) R _onA = R _onB (N2 / N1) = R _onB / 1000 (3) The on-resistance R _onA of the main semiconductor element QA is usually 3
It is about 0 [mΩ]. At this time, the ON resistance R _onB of the reference semiconductor element QB is 30 [Ω].

The reference resistance Rr is set to 2.4 [kΩ]. The drain currents of the main semiconductor element QA and the reference semiconductor element QB are respectively _IDA and _IDB , and the power supply voltage VB = 12
[V], Becomes The drain-source voltages of the main semiconductor element QA and the reference semiconductor element QB are V _DSA and V _DSB , respectively.
Then, V _DSB = R _onB × I _DB = 30 [Ω] × 5 [mA] = 0.15 [V] (5) V _DSA = R _onA × I _DA = 30 [mΩ] × I _DA (( _{6) V DSA -V DSB = 30} [mΩ] (I DA -5 [a]) ... a (7). When I _DA = 5 [A], V _DSB = V _DSA , when I _DA <5 [A], V _DSA <V _DSB , and when I _DA > 5 [A], V _DSA > V _DSB .

The comparator CMP1 is based on the power supply voltage VB.
(+) And (-) input terminal voltages are considered. CMP1
(-) The input terminal is connected between the drain and the source of the reference semiconductor device QB.
Source voltage V_DSBIs added. On the other hand, CMP1
(+) The input terminal is the drain to source of the main semiconductor device QA.
Voltage divided by resistors R1 and R2 is applied.
You. That is, assuming that the voltage drop of the resistor R1 is VR1, V_R1= V_DSA× (R1 / (R1 + R2)) voltage V determined by (8)_R1To the (+) input terminal of CMP1
Added. V_R1= V _DSBV_DSATo V
_DSAthThen, V_DSB= V_DSAth× (R1 / (R1 + R2))… (9) V_DSAth-V_DSB= (R2 / R1) × V_DSB... (10) In this example, from equation (1), I_DA= 5 [A]
Sometimes V_DSA= V_{DS B}And from equation (8), V
_DSA> V_R1In this state, V_R1<V
_DSBBecomes

When V _R1 <V _DSB , the output of CMP 1 becomes “H” and the source transistor Q in the drive circuit 111
5 turns on, the sink transistor Q6 turns off, the charge pump voltage VP is applied to the gates of the main semiconductor element QA and the reference semiconductor element QB, and the main semiconductor element QA and the reference semiconductor element QB turn on.

V_DSAIs V_DSBLarger, (1
V shown by equation (0)_DSAthWhen it becomes larger, V_R1
> V_DSBBecomes At this time, I_DAIs greater than 5 [A]
It is in a so-called over-current state because it is getting sharper. C
The output of MP1 becomes “L”, and the
Transistor Q5 is turned off and sink transistor Q6
Turns on and the main semiconductor element QA and the reference semiconductor element QB
Since the gate circuit is grounded, the main semiconductor element QA and the base
The quasi-semiconductor element QB enters an off operation. When entering off operation
V_DSAAnd V_DSBIncreases and I_DAAnd I_DBIs reduced
Less. Therefore V_DSAAnd V_DSBThe difference between
On the other hand, as can be seen from equation (10), V _DSBIs large
V_DSAth-V_DSBSteadily large
It will be good. Therefore, V_DSAAnd V_DSBGrows larger
As V_R1<V_DSBIs established again, and CMP1
The output becomes “H”, and the main semiconductor element QA and the reference semiconductor
The element QB turns on. In other words, the main semiconductor
The element QA and the reference semiconductor element QB perform on / off operation.
It will be. Built-in element when on / off operation continues
Main semiconductor element by overheating cutoff function by the temperature sensor
Turn off QA. Alternatively, timer for ON / OFF duration
To shut off the main semiconductor device QA.
You. Thus, the power supply shown in FIG.
If the load current flowing through element QA is equal to or less than a predetermined value,
Continue to supply power to the load, and
When a current flows, the main semiconductor device QA is shut off after a certain time.
To prevent burnout of wiring and power supply itself due to overcurrent
are doing.

[0011]

However, in the conventional power supply device, the comparator CMP1 compares the source potential of the main semiconductor element QA with the source potential of the reference semiconductor element QB in order to detect current. ing. Comparator CMP
The (+) and (-) input terminals of the main semiconductor element QA
And the source potential of the reference semiconductor element QB are input,
The source potentials of the main semiconductor element QA and the reference semiconductor element QB change within the range of the power supply voltage VB. The source potential of the main semiconductor element QA may change beyond the power supply voltage range VB due to the inductance of the wiring through which the load current flows. Therefore, the CMP1 and the (+) and (-) input terminals of the CMP1 must have a withstand voltage equal to or higher than the power supply voltage VB. On the other hand, the power supply system of an automobile is currently mainly 12 V system, in which case the power supply voltage V
The maximum value of B may be about 18V. But,
Recently, in order to reduce power loss due to load current, boosting of a power supply voltage has been studied, and a 42V power supply has been specifically studied. In this case, the main semiconductor element QA, the reference semiconductor element QB, and the drive circuit thereof must be improved in breakdown voltage to a breakdown voltage required for a 42 V power supply system.

At this time, in the conventional method, the breakdown voltage of the comparator CMP1 also needs to be increased. Comparator CMP
Control circuits such as 1 are manufactured by a CMOS process or a BiCMOS process. However, it is necessary to increase the breakdown voltage of the element structure and to improve the process accordingly. The method of increasing the breakdown voltage is
There are a method of increasing the number of elements having the same withstand voltage, a method of increasing the thickness of the gate insulating film, and a method of improving the withstand voltage of the element itself by forming a guard ring or a field plate. However, the method of increasing the number of elements requires an increase in a chip area, a complicated process, and the like, resulting in an increase in component costs. For higher breakdown voltage, if increasing the thickness of the gate insulating film, the performance (electrical characteristics) such as transconductance g _m of the device is reduced. Also, using the element in an environment with a high withstand voltage may cause a reduction in the reliability of the element.

Even if the power supply voltage is increased, if the control circuit can use a conventional withstand voltage element, it is possible to prevent an increase in parts cost and to secure the reliability of the element. That is.

An object of the present invention is to solve the above-mentioned conventional problems and circumstances. Even when the power supply voltage shifts from a conventional 12V system to a high-voltage power system such as a 42V system, the first embodiment can be used. And the second of the semiconductor elements of the second semiconductor element
As a comparator for comparing the potential between the main electrodes
An object of the present invention is to provide a semiconductor device which can use a V-type element.

Another object of the present invention is to provide a semiconductor device which does not require a high withstand voltage of a comparator used in a control circuit and can avoid an increase in cost accompanying the high withstand voltage.

Still another object of the present invention is to provide a semiconductor device capable of improving reliability by avoiding use of a comparator used in a control circuit under a high voltage environment.

[0017]

A first feature of the present invention is as follows.
A first main electrode connected to a DC power supply, a second main electrode connected to a load
A first semiconductor element having a main electrode and a control electrode of
A second main electrode having a first main electrode connected to a first main electrode of the first semiconductor element, a second main electrode connected to a reference circuit, and a control electrode connected to a control electrode of the first semiconductor element; Comprising a semiconductor element, a high power supply terminal and a low power supply terminal,
A comparator having a first input terminal connected to the second main electrode of the first semiconductor element and a second input terminal connected to the second main electrode of the second semiconductor element; A drive circuit for supplying a control voltage to each of the control electrodes of the first and second semiconductor elements, a first diode connected between the first input terminal and the lower power supply terminal, and a second input terminal. And a second diode connected between the lower power supply terminal via a resistor. Then, when an overcurrent exceeding a predetermined current value determined by the reference circuit flows through the first semiconductor element, on / off control of the first semiconductor element is performed to generate a current oscillation. The conduction state of the semiconductor element is cut off. here,
The “reference circuit” includes various circuits such as a constant current source and a parallel circuit of a resistor and a constant current source, in addition to the reference resistor. The high power supply terminal is maintained at the system power supply voltage, and the voltage between the high power supply terminal and the low power supply terminal is maintained at a voltage lower than the system power supply voltage. The first and second semiconductor elements are MOS field effect transistors (FE).
T), MO such as MOS static induction transistor (SIT)
An insulated gate power device such as an S transistor and an insulated gate bipolar transistor (IGBT) can be used. Alternatively, various MOS composite devices such as an emitter switched thyristor (EST) may be used. These semiconductor elements may be of an n-channel type or a p-channel type. The “first main electrode” is an IGB
T means one of an emitter electrode and a collector electrode, and T means one of a source electrode and a drain electrode in an insulated gate transistor such as a MOS transistor. The “second main electrode” is one of the emitter electrode and the collector electrode that does not become the first main electrode in the IGBT, the source electrode or the collector electrode that does not become the first main electrode in the insulated gate transistor. It means any one of the drain electrodes. That is, the first
If the main electrode is an emitter electrode, the second main electrode is a collector electrode, and if the first main electrode is a source electrode, the second main electrode is a drain electrode. The “control electrode” means, of course, the gate electrode of the IGBT and the insulated gate transistor.

In particular, by connecting a first diode between the first input terminal and the lower power supply terminal of the comparator and a second diode between the second input terminal and the lower power supply terminal, The input voltage of the comparator can be clamped by the forward drop voltage. Furthermore, if a constant voltage diode such as a Zener diode is connected between the high power supply terminal and the low power supply terminal of the comparator, the comparator can be protected from high voltage. Preferably, a third semiconductor element is connected between the DC power supply and the higher power supply terminal. In particular, the ratio of the number of unit elements forming each semiconductor element may be determined so that the current capacity of the second semiconductor element is smaller than the current capacity of the first and second semiconductor elements. By selecting the number of unit elements as described above and setting the layout of the planar pattern of the power IC, the circuit configuration of the second semiconductor element can be reduced in size, the area of the semiconductor chip can be further reduced, and high voltage The manufacturing cost of a semiconductor device that meets conditions can be significantly reduced.

[0019]

Next, an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

A high-voltage current oscillator according to an embodiment of the present invention
As shown in FIG. 1, a semiconductor device with a dynamic shut-off function
Section input terminal T₁The first main electrode DA connected to the first
External output terminal T₃The second main electrode SA connected to
A first semiconductor element QA having a control electrode GA;
Force terminal T₁The first main electrode DB connected to the
Output terminal T₃To the second main electrode SB connected to the first
Control electrode GB connected to control electrode GA of semiconductor device QA
Semiconductor device QB having the following, and a second semiconductor device
QB second main electrode SB and second external output terminal T₃Through
The reference resistor Rr as a reference circuit connected through
Power supply terminal N_HAnd the lower power supply terminal N_LAnd the first
Connect the first input terminal to the second main electrode of the semiconductor device QA
And a second input to the second main electrode of the second semiconductor element QB.
The comparator CMP1 with the connected terminal and the output of the comparator CMP1
The first semiconductor element QA and the second semiconductor element
Supply control voltage to control electrodes GA and GB of child QB
Drive circuit 111, a first input terminal and a lower power supply terminal
N_LA first diode D21 connected between
Input terminal and low power supply terminal N_LConnected via a resistor R28
At least comprising a second diode D22 connected
Have been. Then, the first external output terminal T ₃Connected to
The current flowing through the load 102 is a reference circuit (reference resistance).
When the current value exceeds a predetermined current value determined by Rr, the first
On / off control of semiconductor device QA to generate current oscillation
However, due to this current oscillation, the external input terminal T₁And the first outside
Output terminal T₃The conduction between them is cut off.

In this example, the reference circuit is used as a "reference circuit".
Although the quasi-resistance Rr was used, in addition to the reference resistance Rr, a constant current source
(Constant current circuit) or parallel circuit of resistor and constant current circuit
Etc. can be used. As a reference circuit
When the anti-Rr is used, the reference resistance R is set to the current capacity ratio n (this
N = 1000), that is, Rr / n = R
By comparing the magnitude relationship between r / 1000 and the load resistance,
When the resistance becomes smaller than Rr / n, the first semiconductor element Q
A is turned on / off. On the other hand, a constant current
Source I_refWhen using_refThe current capacity ratio
Current value, that is, n × I_ref= 1000 × I_refWhen
By comparing the magnitude relationship of the load currents, n × I _refMore load
When the current increases, the first semiconductor element QA is turned on /
Turn off. A resistor and a constant current source
When configured as a column circuit, the combined resistance reference and current reference
Characteristics. These reference circuits are used to detect abnormalities on the load side.
It is preferable to use differently depending on what state is determined.

As shown in FIG. 2, the first semiconductor device QA
It is preferable to connect a heating cutoff circuit 120 between the gate electrode GA and the source electrode _SA. (If a method of measuring the number of current vibrations is adopted, the heat cutoff function of the heating cutoff circuit 120 may be used.) Is not required.) The heating cutoff circuit 120 shown in FIG.
MOS transistor QS connected to the gate electrode GA, and the MOS transistor QS
And a temperature sensor 121 that controls the state of the latch circuit 122. In other words, the temperature sensor 1 indicates that the surface temperature of the semiconductor chip 110 has risen to a temperature equal to or higher than the specified temperature.
When the detection is performed by the detection circuit 21, the state of the latch circuit 122 changes according to the detection information from the temperature sensor 121, and this state is held by the latch circuit 122. As a result, the overheat cutoff MOS transistor QS is turned on, short-circuiting the gate electrode GA and the source electrode SA of the first semiconductor element QA, and forcibly turning off the first semiconductor element QA.

Here, the temperature sensor 121 has four diodes made of polysilicon or the like connected in series.
The temperature sensor 121 is integrated near the first semiconductor element QA. As the junction temperature of the first semiconductor element QA increases, the surface temperature of the semiconductor chip increases, and the forward voltage drops of the four diodes of the temperature sensor 121 gradually decrease. When the sum of the forward drop voltages of the four diodes decreases to a potential at which the gate potential of the nMOS transistor Q51 is set to the “L” level, the nMOS
The transistor Q51 turns off from the on state. As a result, the gate potential of the nMOS transistor Q54 is pulled up to the potential of the gate control terminal G of the first semiconductor element QA, and the nMOS transistor Q54 is turned on. Therefore, the nMOS transistor Q53 is turned off, the nMOS transistor Q52 is turned on from the off state, and "1" is latched by the latch circuit 122. At this time, the output of the latch circuit 122 becomes “H” level, and the overheat cutoff element QS is turned on from the off state. As a result, the first semiconductor element Q
The true gate TG of A and the second main electrode (source electrode) SA are short-circuited, the first semiconductor element QA is turned off from the on state, and overheat is cut off.

As shown in FIG. 1, the semiconductor device used in the high voltage condition according to the present invention is a semiconductor integrated circuit in which a first semiconductor element QA and a control circuit for the first semiconductor element are integrated on the same substrate. (Power IC). The control circuit detects a current flowing in the load 102 connected to the first semiconductor element QA, and when an abnormal current occurs, on / off controls the first semiconductor element QA to generate a current oscillation. It has a function of interrupting the first semiconductor element QA by current oscillation. As a substrate constituting the power IC, an insulating substrate such as ceramic or glass epoxy, an insulated metal substrate, or the like may be used, and a hybrid IC may be used. However, more preferably, it should be a “monolithic power IC” monolithically integrated on the same semiconductor substrate (same chip).

As the first semiconductor element QA, for example,
Power MOS transistor of DMOS structure, VMOS structure or UMOS structure or MOS of similar structure
SIT is available. Further, a MOS composite device such as an EST or a MOS control thyristor (MCT) may be used.
Further, other insulated gate power devices such as IGBTs can be used. Furthermore, if the gate is always used with a reverse bias, a junction type MOS transistor, a junction type SIT
And an electrostatic induction thyristor (SI thyristor) can also be used. The first semiconductor element QA used for the high-voltage power IC may be an n-channel type or a p-channel type. That is, the semiconductor device of the present invention has an n-channel type and a p-type.
There are both channel types. In the following description,
A case in which an n-channel semiconductor device is used as a high-side (High-Side) element will be described.

As the first semiconductor element QA, for example, a power device having a multi-channel structure in which a plurality of unit elements (unit cells) are connected in parallel may be used.
The second semiconductor element QB is connected to the first semiconductor element QA so as to be connected in parallel to the first semiconductor element QA.
It is arranged at a position adjacent to. The heating cutoff circuit 120 is not essential for the second semiconductor element QB. Second
Are arranged at adjacent positions in the same process as the first semiconductor element QA, so that variations in electrical characteristics due to the influence of temperature drift and non-uniformity among lots are eliminated (reduced). it can. Second semiconductor element QB
Is adjusted so that the current capacity of the first semiconductor element QA becomes smaller than the current capacity of the first semiconductor element QA. For example, by configuring the number of unit elements of the first semiconductor element QA to be 1000 with respect to the number of unit elements of the second semiconductor element QB being 1, the second semiconductor element QB and the first semiconductor element The ratio of the channel width W of QA is set to 1: 1000. Further, the temperature sensor 121 is connected to the second semiconductor element QB
And a plurality of diodes composed of a polysilicon thin film or the like deposited on an interlayer insulating film formed on the first semiconductor element QA, which are connected in series, and the temperature sensor 121 is connected to the first semiconductor element QA. Are integrated at positions near the channel region.

The operation of the semiconductor device of the present invention will be described with reference to FIG. When the operation switch SW1 provided outside the semiconductor chip 110 is turned on, an ON signal is input to the drive circuit 111 via the external input terminal T2, and the voltage VP boosted by a charge pump circuit (not shown) is supplied to the resistor R8,
R7 is applied to the gates TG of the first and second semiconductor devices QA and QB via the first semiconductor device QA and the second semiconductor device QA.
Semiconductor element QB is turned on. The value of the voltage VP is, for example, VB + 10 V when the power supply voltage is VB.

The ON resistance per MOS transistor unit element constituting the first semiconductor element QA and the second semiconductor element QB is R _fet, and the first semiconductor element QA
A, and the on-resistance of the second semiconductor element QB is R
_Assuming that _onA and _RonB , when the first semiconductor element QA and the second semiconductor element QB are completely turned on, that is, in the ohmic region, the above equations (1) to (3) are satisfied. R _onA is usually about 30 [mΩ]. At this time, R _onB = 30 [Ω]. Here, Rr = 8.4 [k
Ω]. When the drain current of the first semiconductor element QA and the second semiconductor element QB and _{I DA} and _{I DB,} respectively, and power supply voltage VB = 42 [V], Becomes First semiconductor element QA and second semiconductor element Q
The drain-source voltage of B is V _DSA and V
_{If DSB} is used, the above-described equations (5) to (7) hold.

When I _DA = 5 [A], V _DSB = V
_{DSA next,} I DA <5 [A] in _{V D} SA <V
_{DSB next, I} DA> 5 [A] in the _{V DSA> V
DSB} .

When the switch SW1 is turned on, the pnp transformer
The transistor Q11 turns on, and the high-order power supply terminal of the comparator CMP1
N_HIs supplied with a power supply voltage. Low voltage of comparator CMP1
Source terminal N_LIs grounded via a resistor R27, and N_HAnd N_L
The Zener diode ZD2 is connected between
Assuming that the Zener voltage of ZD2 is 12 [V], CMP
The voltage between the high power supply terminal and the low power supply terminal of No. 1 is 12 [V].
And the voltage is kept lower than the power supply voltage VB = 42 [V].
Will be held. Low power supply terminal N of CMP1 _LNo electricity
Rank V_NLIsIs kept.

The drain current I of the first semiconductor element QA
_{When DA} is less than or equal to 5 [A], the output of the comparator CMP1 becomes “H” because V _DSA <V _DSB , the pnp transistor Q12 is turned off, and the drive circuit 111 causes the first semiconductor element QA and the second Of the semiconductor element QB is kept on. On the other hand, the drain current I _{DA of} the first semiconductor element QA
_Exceeds 5 [A], V _DSA > V _DSB , the output of the comparator CMP1 becomes “L”, and the pnp transistor Q12 turns on. Therefore, the source transistor Q5 of the drive circuit 111 is turned off, the sink transistor Q6 is turned on, and the first semiconductor element QA and the second semiconductor element QB are turned on.
Is grounded via resistors R7 and R8. Therefore, the first semiconductor element QA and the second semiconductor element QB enter an off operation. That is, 5 [A] is the power supply voltage VB = 42.
This is the overcurrent determination value at the time of [V]. The load resistance at this time is 42 [V] / 5 [A] = 8.4 [Ω], which is n
× Rr = 1000 × 8.4 [mΩ]. That is,
8.4 [Ω] is the overload determination value, and the load resistance is 8.4.
When the resistance becomes [Ω] or less, the first semiconductor element QA and the second semiconductor element QB enter an off operation. Overload judgment value 8.4
[Ω] is constant regardless of the power supply voltage VB. This is because a resistor is used as the reference circuit. If a constant current circuit is used as the reference circuit, the overcurrent determination value becomes equal to the power supply voltage V
It is constant regardless of B.

First semiconductor device QA, second semiconductor device
When the QB enters the off operation, the first semiconductor element QA and the second
Voltage V between doin and source of semiconductor device QB_DSA, V
_DSBIncreases. First semiconductor device QA, second semiconductor
The source potential of the body element QB is V_{S A}, V_SBThen V
_SA, V_SBIs lowered toward the ground potential GND.
Good. The sink transistor Q6 of the drive circuit 111 turns on.
Therefore, the source of the first semiconductor element QA → the resistor R81 → the resistor
Anti-R26 → diode D1 → resistor R8 → sink transistor
A current flows through the path of the star Q6 → GND, and the
(+) Hysteresis effect that lowers the input terminal potential
And the output of CMP1 stably maintains “L”.
The input terminal potential of CMP1 is also V_SA, V_SBAlong with the decline
The CMP1 (+) input terminal potential is C
MP1 potential V of low power supply terminal_NLAnd the diode D21
More clamped, V_NL-0.7 [V] (in the order of D21
Direction voltage drop). V_NL= VB-1
Since 2.3 [V], the potential of the CMP1 (+) input terminal is V
It does not drop below B-13 [V]. On the other hand, CMP1
(-) Input terminal is also clamped by diode D22.
However, since it is clamped via the resistor R28, the CMP
The (-) input terminal voltage of 1 is the voltage drop of R28,
(+) Clamped to a potential lower than the input terminal potential. Immediately
(−) The clamp potential of the input terminal is VB-13 [V]-
(R28 voltage drop). Therefore V_SA, V _SB
Is lowered and the clamp voltage is input to CMP1.
The output of CMP1 is not related to the state of the load side.
Instead, the driving circuit 111 again outputs the first semiconductor
The element QA and the second semiconductor element QB are turned on.
V_SA, V_SBIs lower than the clamp voltage, the control circuit and
After the delay time of the MOS transistor, the first semiconductor element Q
A, the second semiconductor element QB is turned on, and V_SA, V_SBBut
Control circuit and MOS transistor when clamp voltage is exceeded
After the delay time of the first semiconductor device QA and the second semiconductor device
Since the element QB is turned off, the on / off operation must be continued.
become. When the on / off operation continues for a certain period of time, the first half
Due to overheating of the conductor element QA or by timer processing
Block the first semiconductor element QA and the second semiconductor element QB.
Refuse.

(Other Embodiments) It should not be understood that the description and drawings which form part of the disclosure of the above embodiment limit the present invention. From this disclosure, various alternative embodiments, examples, and operation techniques will be apparent to those skilled in the art.

For example, while FIG. 1 shows an n-channel high-side circuit, a p-channel high-side circuit as shown in FIG.
If (p) is used, it can be realized with a substantially similar circuit configuration.

In a certain case, as shown in FIG.
A configuration in which the Zener diode ZD2 shown in FIG.

As described above, the present invention naturally includes various embodiments and the like not described herein. Therefore, the technical scope of the present invention is determined only by the invention specifying matters according to the claims that are appropriate from the above description.

[0037]

According to the semiconductor device of the present invention, even when the power supply voltage shifts from a conventional 12V system to a high voltage power system such as a 42V system, the semiconductor elements of the first and second semiconductor elements can be used. As a comparator for comparing the potential between the second main electrodes, a conventional 12 V-based element can be used. Accordingly, it is not necessary to increase the breakdown voltage of the comparator, and it is possible to avoid an increase in cost due to the increase in breakdown voltage.

Further, according to the semiconductor device of the present invention, it is possible to improve reliability by avoiding use of the comparator under a high voltage environment.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a high-voltage semiconductor device according to an embodiment of the present invention (in the case of n-channel).

FIG. 2 is a circuit configuration diagram of a heating cutoff circuit integrated with the semiconductor device according to the embodiment of the present invention;

FIG. 3 is a circuit configuration diagram of a high-voltage semiconductor device according to another embodiment of the present invention (in the case of a p-channel).

FIG. 4 is a circuit configuration diagram of a high-voltage semiconductor device according to still another embodiment of the present invention (p-channel case).

FIG. 5 is a circuit configuration diagram of a conventional power supply control device.

[Explanation of symbols]

101 Low voltage power supply 102 Load 110, 118, 121, 122 Semiconductor chip 111 Drive circuit 120 Heat cutoff circuit 191 High voltage power supply CMP1 Comparator D1, D21, D22 Diode QA First semiconductor element QB Second semiconductor element Q71, Q72 , Q131, Q221, Q311, Q3
12 MOS transistor RG Gate resistance R1, R2, R5, R7, R8, R10, R21, R2
2, R81, R82 resistor Rr reference resistor _{T 1, T 2, T 3} , T 4 output terminals ZD1, ZD2 a Zener diode

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H03K 17/04 H01L 27/08 102J 17/10

Claims (5)

[Claims] 1. A first semiconductor element having a first main electrode connected to a DC power supply, a second main electrode connected to a load, and a control electrode, and a first main electrode of the first semiconductor element. A first main electrode connected to a reference circuit, a second main electrode connected to a reference circuit, and the first main electrode.
A second semiconductor element having a control electrode connected to a control electrode of the semiconductor element, and a high power supply terminal and a low power supply terminal, wherein the high power supply terminal is held at a system power supply voltage, and the high power supply terminal A second input terminal connected to a second main electrode of the first semiconductor device, wherein a voltage between the second power supply terminal and the lower power supply terminal is maintained at a voltage lower than a system power supply voltage; A comparator in which a second input terminal is connected to a second main electrode, and a drive circuit that supplies a control voltage to control electrodes of the first and second semiconductor elements in accordance with an output of the comparator. A first diode connected between the first input terminal and the lower power supply terminal, and a second diode connected via a resistor between the second input terminal and the lower power supply terminal; Predetermined current determined by the reference circuit When an overcurrent exceeding the value flows through the first semiconductor element, the first semiconductor element is turned on / off to generate a current oscillation, and the current oscillation causes the first semiconductor element to conduct. A semiconductor device, wherein a state is interrupted. 2. The semiconductor device according to claim 1, wherein the first semiconductor element is composed of N1 unit elements, and the second semiconductor element is composed of N2 unit elements, wherein N1≫N2. The semiconductor device according to claim 1. 3. A constant voltage diode is connected between the high power supply terminal and the low power supply terminal.
Or the semiconductor device according to 2. 4. A third power supply between the DC power supply and the high power supply terminal.
The semiconductor device according to claim 1, wherein the semiconductor device is connected to the semiconductor device. 5. The semiconductor device according to claim 1, wherein said first and second semiconductor elements, said comparator, said driving circuit, and said first and second diodes are integrated on a same semiconductor substrate. The semiconductor device according to any one of claims 4 to 4.