JP2001197723A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize collect over-current determination by compensating fluctuation in over-current determination, resulting from fluctuation in the dividing coefficient of sense current or the main current in an IGBT element and in resistance of a current detecting resistor. SOLUTION: A value of the reference voltage Vref of an over-current determination reference power supply 6 is set by adjusting an adjusting resistor R2 to a value of node voltage V1, when the main current Ic reaches the over- current condition which is determined for each product based on the current dividing coefficient of the sense current Is of the semiconductor element Q1 and the valve of current detecting resistor R1. As a result, when the main current Ic reaches the over-current condition, the over-current protection circuit 1 can detect generation of the over-current condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device suitable for use in a power conversion device such as an inverter device, and more particularly to a technique for reducing or eliminating variations in overcurrent determination value and temperature dependency.

[0002]

2. Description of the Related Art A semiconductor device having a semiconductor element such as an IGBT element and an overcurrent protection function for detecting that an overcurrent has flowed through the semiconductor element and preventing a characteristic deterioration of the semiconductor element is known. , Power conversion devices such as inverter devices.

FIG. 8 is a diagram showing a configuration of a semiconductor device 10P having a conventional overcurrent protection circuit. As shown in FIG.
By making a part of the semiconductor element Q1P have a cell isolation structure,
During its operation, the semiconductor element Q1P outputs, from its sense terminal 7P, a sense current Is having a constant shunt rate with respect to the main current Ic input from the terminal 3P. This allows
The sense current Is flows through the current detection resistor R1P, and the comparator C1P in the current protection determination circuit 1P detects the voltage drop generated in the current detection resistor R1P and the overcurrent determination reference voltage Vref.
To determine the overcurrent state. At this time, when the voltage between both ends of the current detection resistor R1P exceeds the reference voltage Vref and the comparator C1P determines that the overcurrent state is present, the current protection determination circuit 1P sets the gate drive circuit 2
A gate cutoff signal is sent to P, and as a result, the gate drive circuit 2P stops driving the gate even if the gate drive signal input from the gate terminal 4P is input to the circuit 2P. Thereby, the input of the main current Ic is limited, and the characteristic deterioration of the semiconductor element Q1P due to the overcurrent is prevented.

[0004]

In a conventional semiconductor device having an overcurrent protection circuit having a configuration as shown in FIG.
For example, the value of the main current when the overcurrent state is determined due to variation in the shunt ratio of the sense current with respect to the main current depending on the manufacturing process of the semiconductor chip, or variation in the value of the current detection resistor (hereinafter, referred to as There is a problem that variation occurs in the overcurrent determination value), making it impossible to accurately determine the overcurrent state. Therefore, in order to prevent such a variation in the overcurrent determination value and to ensure accurate determination, it is necessary to select a semiconductor element having a sense current shunt rate within an appropriate range, or to select a semiconductor element having a current detection resistance. It is necessary to deal with this by increasing the resistance value. However, such a measure results in an increase in the cost of the apparatus, and a drastic solution is required.

In recent years, in order to use an overcurrent protection circuit not only for protection of a single semiconductor element but also for protection of the entire system using the semiconductor element, it is required to increase the accuracy of an overcurrent determination value. The tendency is to be even stronger.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to make it possible to cope with a high accuracy of an overcurrent judgment value, and to make the present invention more effective. An object of the present invention is to provide a semiconductor device capable of performing an overcurrent protection operation.

[0007]

According to a first aspect of the present invention, there is provided a semiconductor device having a cell isolation structure capable of outputting a sense current given at a predetermined shunt rate to a main current from a sense terminal thereof. An element, a determination reference power supply that outputs a reference voltage serving as a reference for determination, n (n is a positive integer of 1 or more) current detection resistors connected in series between the sense terminal and a ground potential, When the sense current flows through the n current detection resistors, each of the n node voltages between adjacent current detection resistors and between the sense terminal and the current detection resistor connected to the sense terminal. Comparing with the reference voltage, the main current should be cut off when at least one of the n node voltages is equal to or higher than the reference voltage within a predetermined determination time corresponding to the node voltage; To the state And a gate drive circuit that receives the gate cutoff signal output from the current protection determination circuit and stops driving the gate of the semiconductor element. The semiconductor device is connected between the reference power supply and the ground potential, and the flow of the semiconductor device should be interrupted by adjusting its own resistance value during or after assembly of the semiconductor device. The n generated when the main current that has reached the original determination level flows through the semiconductor element.
An adjustment resistor for adjusting the reference voltage so that any one of the node voltages becomes equal to the reference voltage is further provided.

A semiconductor device according to a second aspect of the present invention is the semiconductor device according to the first aspect, wherein the adjustment resistor has a relatively small reference voltage at an initial stage of the adjustment. And the resistance value adjusted so that the reference voltage becomes relatively large.

A semiconductor device according to a third aspect of the present invention is the semiconductor device according to the first or second aspect, wherein the resistance value of the adjustment resistor is such that the temperature dependence of the reference voltage is n. Has a temperature coefficient capable of compensating for the temperature-dependent characteristics of each of the node voltages.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) First, the focus of this embodiment will be described. That is, in the conventional semiconductor device shown in FIG. 8, the node voltage V1 does not have all of the above variations due to variations in the shunt rate of the individual semiconductor elements Q1P and variations in the values of the individual current detection resistors R1P. Despite the fact that the reference voltage Vref is different from the desired value, the reference voltage Vref remains fixed.
In practice, the current protection determination circuit 1P may determine that the main current is in the overcurrent state without reaching the overcurrent state, or vice versa. This is because the node voltage V1 varies for each device under the influence of the above-described variation, but the reference voltage Vref cannot follow the variation. Therefore, in the present embodiment, the reference voltage is made equal to the voltage drop at the current detection resistor caused by the sense current flowing when the main current level reaches the original (as designed) overcurrent determination value. The reference voltage is adjusted for each semiconductor device. Hereinafter, a specific configuration of the present embodiment will be described with reference to the drawings.

FIG. 1 is a diagram showing a circuit configuration of a semiconductor device 10 according to the first embodiment incorporated in a semiconductor power module (not shown). In FIG. 1, Q1 has a cell isolation structure capable of outputting a sense current Is given from the sense terminal 7 at a constant shunt rate (however, the value varies for each element) with respect to the main current Ic. For example I
1 is a current protection determination circuit provided with a comparator C1, 2 is a gate drive circuit that operates a gate according to a gate drive signal input from a terminal 4, and 3 is a semiconductor device. A terminal for inputting the main current Ic to the element Q1. R1 is a current detection resistor connected in series between the sense terminal 7 and the ground potential,
The sense current Is of the semiconductor element Q1 is converted to a voltage (hereinafter, referred to as a node voltage) V1 at a node between the sense terminal 7 and one end of a current detection resistor R1 connected to the sense terminal 7. Reference numeral 5 denotes a DC voltage bus, and reference numeral 6 denotes a determination reference power supply (hereinafter also referred to as an overcurrent determination reference power supply) that outputs a reference voltage Vref serving as a reference for overcurrent determination to the current protection determination circuit 1. R2 is an adjustment resistor connected between the overcurrent determination reference power supply 6 and the ground potential and having an adjustable resistance value. The comparator C1 of the current protection determination circuit 1 in the semiconductor device 10 determines the node voltage V1 having a variation in the voltage value for each device 10 according to the shunt rate of the sense current Is and the variation in the resistance value of the current detection resistor R1.
And the (adjusted) reference voltage Vref after the resistance value of the adjustment resistor R2 is appropriately adjusted by an adjustment method described later.
And by comparing the two voltages V1 and Vref,
It is determined whether or not the level of the main current Ic has reached the original (as designed) overcurrent determination level. That is, when the comparator C1 detects that the node voltage V1 is equal to or higher than the reference voltage Vref for a predetermined judgment time (here, for example, 10 ms), it is determined that the level of the main current Ic is equal to or higher than the overcurrent judgment level. Upon making a determination, a gate cutoff signal is output to the gate drive circuit 2. As a result, the gate drive circuit 2 stops driving the gate of the semiconductor element Q1.

Hereinafter, a specific example of adjusting the reference voltage Vref by adjusting the resistance value of the adjustment resistor R2 will be described. That is, in the present embodiment, the semiconductor device 1
0 during assembly (each part 1 to 6, Q1, R
1 and R2 are formed on the same chip (same semiconductor substrate) and the respective wiring layers are also formed, so that the circuit configuration shown in FIG.
0 or after the completion of the assembly (in this case, after the circuit configuration of the semiconductor device 10 is completed as described above, the semiconductor device excluding the adjustment resistor R2). 10 or each part in the semiconductor power module is resin-encapsulated, so that the adjusting resistor R
In the case where only 2 is an external structure, it corresponds to the stage after the resin encapsulation), and by adjusting the resistance value of the adjustment resistor R2 itself, the main current Ic should be cut off (that is, the main current Ic should be cut off). Judgment level according to design value (here,
The value of the node voltage V1 generated when the main current Ic that has reached the overcurrent determination value) flows through the inside of the semiconductor element Q1 is set to the reference voltage Vr.
The reference voltage Vref is adjusted for each semiconductor device 10 so that the value of ef becomes equal. Such a reference voltage Vre
The adjustment method of f can be executed by using the following as the adjustment resistor R2 and performing the following adjustment. This will be described in detail below.

First, as the adjustment resistor R2, for example,
It consists of a resistor that can be laser-trimmed and a plurality of resistors that are connected in parallel in advance.The resistance can be adjusted by cutting off these resistors using a cutting tool such as a nipper by the required resistance. By connecting one end of a plurality of resistors in common by a necessary resistance value by resistance, or conversely, by wire bonding or soldering (the other ends are connected in common from the beginning) , A resistor composed of a plurality of resistors connected in parallel is used.

Next, as a method of adjusting the reference voltage Vref, for example, the resistance value of the adjustment resistor R2 is set to a certain value, the main current Ic flows through the semiconductor element Q1, and the value of the main current Ic increases. As a result, the main current I when the first comparator C1 outputs the gate cutoff signal is output.
c, that is, an overcurrent determination value, and then adjust resistance R
2, the resistance is changed to a new value, and the overcurrent determination value is measured in the same manner. When the measured overcurrent determination value finally becomes equal to the original overcurrent determination value, the value of the adjustment resistor R2 and the reference voltage Vref at that time are determined.
Are adjusted to the optimum adjustment resistance R2 and the reference voltage Vre, respectively.
Let it be the value of f. According to this method, when the measured overcurrent determination value becomes equal to the original overcurrent determination value, the value of the reference voltage Vref is set to the value of the node voltage V1. In this method, the main current Ic having the level of the original (desired) overcurrent determination value is supplied to the semiconductor element Q
1, the characteristic degradation of the semiconductor element Q1 does not occur within a certain period of time. Therefore, the time when the characteristic degradation of the semiconductor element Q1 starts to occur is sufficiently longer than the determination time of the comparator C1. Is used as a premise.

As a second adjustment method, the resistance value of the adjustment resistor R2 is appropriately determined, and then the main current Ic is caused to flow into the semiconductor element Q1 while gradually increasing.
As a result, the value of the main current Ic when the main current Ic is cut off by the comparator C1 outputting the gate cutoff signal is measured as the overcurrent determination value, and the adjustment resistor R at that time is measured.
2 is also measured. Then, by using a constant correlation equation between the measured overcurrent determination value and the original overcurrent determination value, the resistance of the adjustment resistor R2 when the value of the main current Ic becomes the original overcurrent determination value is obtained. The value is determined or predicted, and the resistance value of the adjustment resistor R2 is adjusted to the determined value. For example, as a result of flowing a current measured to have a level of の of the original overcurrent determination value to the semiconductor element Q1 as the main current Ic, the resistance of the adjustment resistor R2 when the comparator C1 outputs a gate cutoff signal If the value of the reference voltage Vref is determined and the resistance value of the adjustment resistor R2 is finally adjusted to about twice the resistance value, the value of the reference voltage Vref becomes the main current Ic having a level equal to the original overcurrent determination value. Is set to the value of the node voltage V1 when the current flows.

Next, a preferred method of adjusting the adjustment resistor R2 when the adjustment resistor R2 is adjusted by the above-described adjustment method or adjustment method will be described. Here, FIG.
Is the adjustment resistor R2 from the time when the adjustment of the adjustment resistor R2 is started.
7 is an output example of the reference voltage Vref of the overcurrent determination reference power supply 6 up to the time when the resistance value of No. 2 reaches the adjustment limit value. FIG.
As shown in (2), when the adjustment of the adjustment resistor R2 is started (initial adjustment stage), the output voltage value of the reference voltage Vref becomes relatively small, that is, the output voltage value becomes the minimum value within the adjustable range of the reference voltage Vref. Thus, the output voltage value of the reference voltage Vref increases linearly as the adjustment of the adjustment resistor R2 proceeds, that is, the reference voltage Vref
The circuit of the overcurrent determination reference power supply 6 is configured so as to continuously increase monotonically toward the maximum value within the adjustable range of. As a result, the overcurrent determination value at the initial stage of adjustment when the adjustment of the overcurrent determination value is started is the smallest within the adjustable range, and the overcurrent determination value increases as the adjustment proceeds. FIG. 3 is a diagram showing an example of a circuit configuration of the overcurrent determination reference power supply 6 that can realize the method of adjusting the reference voltage Vref as shown in FIG. Here, in resistance adjustment using laser trimming, the resistance value after adjustment can be controlled to be relatively small in the initial stage of adjustment, and the resistance value after adjustment is monotonously increased as the adjustment proceeds. It is possible. Therefore, when laser trimming is used as a method of adjusting the adjustment resistor R2 in the circuit shown in FIG.
Since the value of the reference voltage Vref is set to a larger value as the resistance value of No. 2 monotonously increases, the range in which the value of the overcurrent determination value in the initial stage of adjustment can be adjusted. , The overcurrent determination value can be successively corrected from the minimum value to the increasing value. Therefore, such an adjustment resistor R2
When the adjustment method is adopted, there is no situation in which the characteristics of the semiconductor element Q1 deteriorate during the adjustment of the adjustment resistor R2 or the adjustment of the overcurrent determination value.

As described above, in the semiconductor device 10, the variation in the shunt rate of the sense current Is with respect to the main current Ic depending on the manufacturing process of each semiconductor chip and the variation in the value of the current detection resistor R1 in the manufacturing process. Adjustment of the resistance value of the adjustment resistor R2 during the assembly after the completion of the circuit configuration of the device 10 (before resin sealing) or after the assembly is completed (after resin sealing) in accordance with the variation of the node voltage V1 caused by this. By adjusting the reference voltage Vref, the value of the reference voltage V1 for each semiconductor device 10 reaches the original determination level (desired overcurrent determination value) at which the level of the main current Ic should be cut off. Is set so as to be equal to the value of the node voltage V1 at the time of the above, so that the main current level can be accurately cut off without being affected by both of the above-mentioned variations. It can be determined Te than in current protection determination circuit 1 that has reached Le. In other words, in the prior art, the overcurrent determination value that has varied with respect to the original overcurrent determination level for each individual semiconductor device 10 is changed to the adjustment resistor R2 during the assembly after the circuit formation of the semiconductor device 10 is completed or after the assembly is completed. , It is always possible to exactly equal the original overcurrent determination level. Therefore, there is no need to select the semiconductor element Q1 in order to correct the overcurrent determination value to the original set value or to increase the precision of the current detection resistor R1, thereby greatly reducing the cost of the semiconductor device 10. Can be reduced.

(Modification) The configuration of the first embodiment described above,
That is, at room temperature, there is provided an adjustment resistor R2 having a function of setting the value of the reference voltage Vref equal to the value of the node voltage V1 generated when the main current Ic at the original overcurrent determination level flows through the semiconductor element Q1. It is also possible to further apply the temperature compensation technique described in, for example, JP-A-8-19164 to the configuration. Thus, in addition to the operation and effect of the first embodiment, the semiconductor element Q
1, especially the sense current Is with respect to the main current Ic.
The temperature dependence of the node voltage V1 showing the temperature dependence corresponding to the temperature dependence of the shunt ratio can be compensated by the temperature dependence of the reference voltage Vref. That is,
The shunt rate (Ic / Is) given as the ratio between the main current Ic and the sense current Is in the semiconductor element Q1 decreases (increases) as the junction temperature (Tj) increases (decreases).
Therefore, since the sense current Is increases (decreases), the value of the node voltage V1 when the main current Ic is at the original determination level also increases (decreases) as the junction temperature (Tj) increases (decreases). ). Therefore, the same temperature dependency as the temperature dependency of node voltage V1 is applied to reference voltage V1.
As indicated by ref, the temperature coefficient of the resistance value of the adjustment resistor R2 may be set. Thereby, the temperature dependency of the overcurrent determination value can be compensated, and it is possible to cope with further higher accuracy of the overcurrent determination value. Hereinafter, description will be made with reference to FIGS.

FIG. 4 is a diagram showing an example of a circuit configuration of a semiconductor device 10A according to this modification of the first embodiment using the adjustment resistor R2A. As shown in FIG. 4, the resistance value of the adjustment resistor R2A for adjusting the reference voltage V1 is equal to the reference voltage Vref which can compensate for the temperature-dependent characteristic of the node voltage V1 caused by the temperature-dependent characteristic of the semiconductor element Q1. It has a temperature coefficient that can realize temperature-dependent characteristics. Hereinafter, the temperature characteristics of the adjustment resistor R2A will be specifically described.

FIG. 5 shows a semiconductor device 10A according to this modification.
FIG. 9 is a diagram showing a temperature-dependent characteristic of a resistance value of the adjustment resistor R2A of FIG. In FIG. 5, the horizontal axis represents the junction temperature Tj (° C.) of the semiconductor element Q1, and the vertical axis represents the resistance value of the adjustment resistor R2A when the resistance value when the junction temperature Tj is 25 ° C. is 1.0. It is. Generally, the temperature characteristic of the resistor is small, and as shown by the broken line in FIG. 5, the temperature characteristic of the resistance value of the adjustment resistor R2 shown in FIG. 1 is a flat characteristic. This is the same for the current detection resistor R1 in FIGS.

On the other hand, in order to detect the main current value of the semiconductor element Q1, a sense cell (current detection cell) different from the main cell is formed in the semiconductor element Q1, but the semiconductor element Q1 cannot be ignored (non-flat). Na) There is a temperature characteristic. Therefore, when the temperature characteristics of the main cell and the temperature characteristics of the sense cell are different from each other, the shunt ratio differs depending on the temperature. FIG. 6 shows a semiconductor device 10A according to this modification.
FIG. 6 is a diagram showing a temperature compensation characteristic of an overcurrent determination value of FIG. 6, the horizontal axis represents the junction temperature T of the semiconductor element Q1.
j (° C.), and the vertical axis indicates that the junction temperature Tj is 2
The overcurrent determination value at 5 ° C. (as described above, the adjustment resistance R2 is set to be equal to the original determination level.
This is the overcurrent determination value when the value of A has been corrected by adjusting the resistance value of A) as 1.0.
As shown by the broken line in FIG. 6, when it is detected that the main current Ic has become an overcurrent by comparing the node voltage V1 generated at the current detection resistor R1 with the reference voltage Vref, the above-mentioned shunt is performed for each junction temperature Tj. When the rates are different, the value of the main current Ic when the current protection operation is actually performed by the current protection determination circuit 1 also differs for each junction temperature Tj. On the other hand, in the present modification, the resistance value of the adjustment resistor R2A is given a temperature characteristic as shown by a solid line in FIG. 5 (monotonically increases with a rise in temperature; a positive temperature coefficient). The reference voltage Vref also changes as shown by the solid line in FIG. 5 according to the change in the resistance value of the adjustment resistor R2A, and the temperature dependency of the reference voltage Vref changes with the temperature detection resistance of the semiconductor element Q1. It follows so as to compensate for the change in the node voltage V1 at R1. For this reason, as shown by the solid line in FIG. 6, the overcurrent determination value becomes almost constant without depending on the junction temperature Tj.

As described above, by using the adjusting resistor R2A having the temperature compensation characteristic as shown in FIG. 5 as the adjusting resistor of the semiconductor device 10A, the shunt rate of the semiconductor element Q1 and the resistance of the current detecting resistor R1 are reduced. In addition to correcting the variation in the overcurrent determination value due to the variation in the
Since the temperature-dependent characteristic of 1 can be compensated, it is possible to further cope with a demand for higher accuracy of the overcurrent determination value.

Incidentally, [00] of JP-A-8-19164 is disclosed.
45] In the paragraph, the adjustment resistor R in FIG.
The resistance value of the resistance element R4 corresponding to the p-type resistance layer 2
A desired value can be obtained by adjusting the sheet resistance of No. 4. There is a description. However, the technique of adjusting the resistance value referred to in the publication is performed at a stage when the resistance element R4 is formed on a semiconductor chip, and involves changing a mask used during a semiconductor process and manufacturing conditions. Is used to adjust the resistance value. That is, the adjustment of the resistance value in the same publication is performed after all the components of the semiconductor device 10 of FIG. 1 are formed on the same semiconductor chip and the circuit configuration of the device 10 is completed as in the present embodiment. It is not something that is performed while operating. In other words, in this publication, the value of the resistor R4 is merely adjusted within the upper limit of the manufacturing process regardless of the circuit configuration and operation of the entire device 10. For this reason, according to the adjustment technique disclosed in the publication, it is not possible to adjust the overcurrent determination level to the originally designed overcurrent determination level during or after assembly of the semiconductor device 10 of FIG. On the other hand, the adjustment resistor R2 in the present embodiment adjusts the resistance value R2 while operating the semiconductor device 10 itself during or after assembly of the semiconductor device 10. Therefore, during or after assembly of the semiconductor device 10, the overcurrent determination value can be easily adjusted to the original determination level without being affected by the variation in the shunt rate or the variation in the value of the current detection resistor R1. .

(Embodiment 2) In order to make the protection operation of the semiconductor device work too sensitively or, on the contrary, to always make the protection operation work when necessary, the current protection judgment circuit uses a judgment time and a judgment current value. It is effective to have a plurality of protection judgment values that differ from each other or only the judgment current value. For example, the protection determination areas are set to two areas, an overcurrent area and a short-circuit current area,
By performing the protection determination in accordance with the conditions required for the semiconductor device, it is possible to achieve both protection of the semiconductor element against overcurrent and short-circuit current and stable operation of the semiconductor device.

Table 1 shows an example of conditions for the protection operation of the semiconductor device according to the second embodiment.

[0026]

[Table 1]

Here, the overcurrent region is a mode in which the characteristics of the semiconductor element are degraded if the main current is supplied as it is due to an overload. Usually, a system in which the drive is stopped by software of a controller using a semiconductor device is generally used, and the determination time (for example, 10 ms) is also a margin time for software determination of occurrence of an overcurrent state in the controller. When the overload continues for the determination time or more, the current protection determination circuit outputs a gate cutoff signal and the main current is cut off. On the other hand,
The short-circuit current region is a mode in which it is expected that the characteristics of the semiconductor element will deteriorate unless the flow of the main current is immediately interrupted due to the occurrence of an output short circuit or the like. This is the mode in which protection of the element is given the highest priority.

Next, a circuit configuration of a semiconductor device which realizes such a plurality of protection operations will be described. FIG. 7 is a diagram showing a circuit configuration of a semiconductor device 10B according to the second embodiment. The present semiconductor device 10B basically has the same circuit configuration as the semiconductor device 10 of the first embodiment. However, in the present semiconductor device 10B, a predetermined protection operation is excessively activated, or when necessary. To ensure that the same operation is performed, the following different configurations are provided. That is, FIG.
In the semiconductor device 10B, the current protection determination circuit 1A
Is provided with first and second comparators C1 and C2 having protection judgment values that are different from both the judgment time and the judgment current value or only the judgment current value (the difference in the judgment current values means that the reference voltage Vref And the current detection resistor is divided into first and second current detection resistors R3 and R4 (both current detection resistors R3 and R4 are connected to the sense terminal 7 and the ground). Is connected in series with the potential), the sense current Is of the semiconductor element Q1 is converted to a first node voltage V3 between the sense terminal 7 and the first current detection resistor R3, and the first current detection resistor R3 between the second current detection resistor R4 and the second current detection resistor R4.
It is also converted to the node voltage V4.

The current protection judging circuit 1A always receives the reference voltage Vref and outputs the first sense current Is.
And first and second node voltages V3 and V4 generated when the current flows through a current detection resistor formed of a series connection of the second and second current detection resistors R3 and R4.
4 and the reference voltage Vref. The current protection determination circuit 1A (accordingly, the first and second comparators C1 and C2) determines that at least one of the two node voltages V3 and V4 is the node voltage Vi (1 ≦ i ≦ n; n = 2 in this case). ), It is determined that the main current Ic is in a state to be interrupted when the voltage is equal to or higher than the reference voltage Vref within a predetermined determination time, and a gate cutoff signal is output to the gate drive circuit 2. Thereby, the gate drive circuit 2
Stops the driving operation of the gate of the semiconductor element Q1.

As described above, in order to cause the semiconductor device 10B to perform two different protection judgment operations, it is necessary to set two different judgment current values. In other words, it is necessary to set two node voltages to be applied to the current protection determination circuit 1A. Therefore, in the present semiconductor device 10B, 2
The current detection resistors R3 and R4 are required. However, in this semiconductor device 10B, the first and second comparators C
1, C2 are the first and second node voltages V3 and V4, respectively.
Is compared with the reference voltage Vref of the same current determination reference power supply 6 to obtain two different protection operations (overcurrent protection operation,
It is determined whether or not it is necessary to execute the short-circuit protection operation).
Moreover, the first comparator C1 and the second comparator C
The determination times set to 2 are 10 ms and 0, respectively.
s. Here, for example, the reference voltage V4 is added to the voltage value of the second node voltage V4 generated when the main current Ic having a level equal to the original overcurrent determination value flows into the semiconductor element Q1.
It is assumed that the resistance value of the adjustment resistor R2 is adjusted by using the adjustment method or the adjustment method described in the first embodiment during or after assembly after the circuit configuration in FIG. 7 so that ref becomes equal. As a result, when the main current Ic, which has increased to the value to be determined as an overcurrent, continuously flows through the semiconductor element Q1 for the determination time set in the first comparator C1, the first comparator C1 immediately fails. It detects the occurrence of a current state and outputs a gate cutoff signal. Therefore,
Since the overcurrent protection operation operates even when the main current Ic has not risen to the original overcurrent determination value, the overcurrent protection operation can be activated quickly. The second comparator C2 immediately performs the short-circuit current protection. In this case, however, the overcurrent determination is always made by the first comparator C1, while the reference voltage Vref becomes equal to the second node voltage V4 when the main current Ic equal to the original overcurrent determination value flows. Therefore, only the influence of the variation of the shunt rate of the sense current Is with respect to the main current Ic can be corrected by adjusting the resistance value of the adjustment resistor R2.

Further, the resistance value of the adjustment resistor R2 is changed to the reference voltage V
The value of ref may be adjusted to be equal to the value of the first node voltage V3 when the main current Ic having the level of the original overcurrent determination value flows. In this case, when the level of the main current Ic rises to or above the original overcurrent determination value, the first comparator C1 performs an overcurrent protection operation. Therefore, as long as the first comparator C1 performs the above-described overcurrent protection operation, the influence of both the variation of the shunt rate and the variation of the current detection resistor can be corrected by adjusting the resistance value of the adjustment resistor R2. Note that the main current Ic further rises within the determination time set in the first comparator C1, and the second node voltage V
When 4 becomes equal to or higher than the reference voltage Vref, the second comparator C2 immediately executes the overcurrent protection operation instead of the first comparator C1. Thus, the overcurrent protection operation can be activated immediately when necessary.

As described above, according to the present semiconductor device 10B,
Since the value of the reference voltage Vref is set to be equal to one of the first node voltage V3 and the second node voltage V4 when the main current Ic having the level of the original overcurrent determination value flows. In addition, at least the influence of the variation of the shunt rate of the semiconductor element Q1 is reduced, and in some cases, the influence of the variation of the first and second current detection resistors R3 and R4 is also reduced. Can be performed, the overcurrent protection operation can be made to work sensitively to the original overcurrent determination value, and the short-circuit protection operation can also be made to work too sensitively.

In addition, according to the semiconductor device 10B, the reference voltage Vref of the first and second comparators C1 and C2 can be adjusted at the same time by adjusting the resistance value of the adjustment resistor R2A. It is simple.

FIG. 7 shows an example in which two comparators are provided in the current protection determination circuit 1A for determining overcurrent and short-circuit current.
Further protection operation conditions may be set depending on the application. In other words, to be generalized, if n protection operations are required (here, n ≧ 3), the current protection determination circuit 1A has a determination time determined according to the corresponding protection operation, and A main current having a level equal to the original overcurrent determination value is provided, provided with n comparators for inputting a common reference voltage Vref, and provided with n current detection resistors capable of supplying n node voltages. During or after assembly of the device, the adjustment resistor R2 is adjusted so that the reference voltage Vref becomes equal to one of the n node voltages generated when flowing through the element.

(Modification) (1) The semiconductor device 10B according to the second embodiment illustrated in FIG.
On the other hand, when the adjustment method of the adjustment resistor R2 shown in FIG. 2 described in the first embodiment is employed, similarly to the first embodiment, during the adjustment of the adjustment resistor R2 or the adjustment of the overcurrent determination value. It is possible to prevent a situation in which the characteristics of the semiconductor element Q1 are deteriorated.

(2) Further, the configuration of the above-described modification of the first embodiment is further applied to the semiconductor device 10B of the second embodiment of FIG. 7 or the semiconductor device 10B of the above-described modification (1). It is also possible. Accordingly, in addition to the operation and effect of the second embodiment or the modification (1) described above, the temperature characteristic of the semiconductor element Q1, particularly, the temperature dependence of the shunt ratio of the sense current Is with respect to the main current Ic is supported. First and second node voltages V3 and V4 exhibiting temperature-dependent characteristics
Can be compensated by the temperature dependence of the reference voltage Vref.

[0037]

According to the first aspect of the present invention, variations in the shunt ratio of the sense current with respect to the main current depending on the manufacturing process of each semiconductor chip and variations in the manufacturing of the value of the current detection resistor are caused. In response to the respective variations in the n node voltages that occur, the value of the reference voltage is changed for each individual semiconductor device, and the value of each node when the level of the main current reaches the original determination level at which the main current should be cut off. Since the voltage is set so as to be equal to any one of the voltages, the level of the main current is not affected by the variation of the shunt rate of the sense current with respect to the main current, and the original level of the main current to be cut off is not affected. The fact that the judgment level has been reached can be accurately judged by the current protection judgment circuit. In the case of n = 1, each semiconductor device has its own voltage corresponding to the variation of the shunt ratio of the sense current with respect to the main current and the variation of the node voltage caused by the manufacturing variation of the value of the current detection resistor. The reference voltage value is set to be equal to the value of the node voltage when the main current level reaches the original judgment level at which the main current should be cut off. The current protection determination circuit determines that the level of the main current has reached the original determination level at which the main current should be cut off without being affected by both the variation in the current detection resistance and the manufacturing variation in the value of the current detection resistor. More accurate determination can be made.

According to the second aspect of the present invention, there is an effect that the deterioration of the characteristics of the semiconductor element during the adjustment of the reference voltage can be avoided.

According to the third aspect of the invention, in addition to the effects of the first or second aspect, the temperature dependence of the shunt rate of the semiconductor element can be compensated together, so that the accuracy of the determination level can be further improved. Can respond to requests.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a circuit configuration of a semiconductor device according to a first embodiment of the present invention;

FIG. 2 is a diagram illustrating output characteristics of a reference voltage of an overcurrent determination reference power supply of the semiconductor device according to the first embodiment of the present invention;

FIG. 3 is a diagram illustrating an example of a circuit configuration of an overcurrent determination reference voltage source according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating a modification of the circuit configuration of the semiconductor device according to the modification of the first embodiment of the present invention;

FIG. 5 is a diagram showing temperature dependence of an adjustment resistor of a semiconductor device according to a modification of the first embodiment of the present invention.

FIG. 6 is a diagram illustrating a temperature compensation characteristic of an overcurrent determination value of a semiconductor device according to a modification of the first embodiment of the present invention.

FIG. 7 is a diagram illustrating a circuit configuration of a semiconductor device according to a second embodiment of the present invention;

FIG. 8 is a diagram illustrating a circuit configuration of a conventional semiconductor device.

[Explanation of symbols]

1, 1A current protection judgment circuit, 2 gate drive circuit, 3
Terminal, 4 input terminal, 5 DC voltage bus, 6 overcurrent judgment reference power supply, 7 sense terminal, 10, 10A, 10B
Semiconductor device, Ic main current, Is sense current, Q1
IGBT element (semiconductor element), Vref reference voltage,
V1 Node voltage, R1, R3 Current detection resistor, R2, R
2A adjustment resistor, C1, C2 comparator.

Continued on front page F term (reference) 5G004 AA04 AB02 BA03 BA04 DA04 DC04 EA01 5G053 AA01 AA02 BA01 CA02 EB01 EC03 5H007 AA05 AA07 CA01 CB00 CC03 DA05 DB01 DC02 DC08 EA00 FA03 FA13 5H740 AA08 BA11 BB07 BB07 BB08

Claims (3)

[Claims] 1. A semiconductor device having a cell isolation structure capable of outputting a sense current given at a predetermined shunt rate to a main current from a sense terminal thereof, and a judgment reference power supply for outputting a reference voltage serving as a judgment reference An n (n is a positive integer equal to or greater than 1) current detection resistor connected in series between the sense terminal and a ground potential, and the sense current is generated when the sense current flows through the n current detection resistors. Comparing each of the n node voltages between adjacent current detection resistors and between the sense terminal and the current detection resistor connected to the sense terminal and the reference voltage,
When at least one of the n node voltages is equal to or higher than the reference voltage within a predetermined determination time corresponding to the node voltage, it is determined that the main current is to be cut off and the gate is determined. A semiconductor device, comprising: a current protection determination circuit that outputs a cutoff signal; and a gate drive circuit that stops driving a gate of the semiconductor element in response to the gate cutoff signal output from the current protection determination circuit, The resistance is adjusted between the reference power supply and the ground potential, and the resistance value of the semiconductor device is adjusted during or after assembly of the semiconductor device. An adjusting resistor that adjusts the reference voltage so that any one of the n node voltages generated when the main current flows through the semiconductor element becomes equal to the reference voltage Characterized in that it comprises further,
Semiconductor device. 2. The semiconductor device according to claim 1, wherein the adjustment resistor has a relatively small reference voltage at an initial stage of the adjustment, and the reference voltage increases relatively as the adjustment proceeds. A semiconductor device comprising the resistance value adjusted to: 3. The semiconductor device according to claim 1, wherein the resistance value of the adjustment resistor is such that the temperature dependence of the reference voltage compensates for the temperature dependence of each of the n node voltages. A semiconductor device having a temperature coefficient that can be used.