JPH11121683A - Semiconductor integrated circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor integrated circuit of power transistors having overcurrent detector circuit which do not require provisions for separating shunt resistance for detecting the overcurrent, thereby suppressing the resistance increase of a main current line. SOLUTION: Bonding wires 317 which are always necessary for mounting a semiconductor chip 302 are used as detecting resistances of overcurrent detector circuits. There is no need for inserting new shunt resistances in series in a main current line, hence avoids increasing the on-resistance of the entire semiconductor integrated circuit is avoided, resolves the problem of requiring a complicated manufacturing process, and reduces the integrated circuit area just by the portion of the area for the shunt resistances.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor integrated circuit having an overcurrent detection circuit in a power transistor for driving an external load.

[0002]

2. Description of the Related Art As a conventional semiconductor integrated circuit having an overcurrent detecting circuit in a power transistor for driving an external load, there is one disclosed in, for example, Japanese Patent Application Laid-Open No. 7-77546. In the above-described conventional device, a shunt resistor is inserted in the middle of a main current path passing through an external load, a power transistor, and a power supply, and a potential difference generated at both ends of the shunt resistor and a predetermined reference value are compared using a comparison circuit. In comparison, when the potential difference is equal to or greater than the reference value, it is determined that the current value flowing through the shunt resistor, that is, the load current flowing through the load or the power transistor exceeds the reference value, and the power transistor is turned off. It is configured.

[0003]

As described above, in the conventional device, the shunt resistor is inserted in series with the load and the power transistor, so that the on-resistance is increased by the amount of the shunt resistor. In order to compare the potential difference between both ends of the shunt resistor with the reference value by the comparator, at least about 200 mV is required as the potential difference. Therefore, the shunt resistance value usually needs to be about several tens mΩ. Since this value is substantially equal to the on-resistance of the power transistor, the overall on-resistance is less than twice. As described above, when the overall on-resistance increases, there is a problem that the current flowing to the load decreases. In addition, since a solenoid load forms a series circuit of LR, there is also a problem that the time constant becomes large and the rise becomes poor. Further, when integrated on a chip, the chip area is increased by the amount of the shunt resistor. In particular, since the shunt resistor has a low resistance and a large current flows, a large area is required, so that the entire area becomes large and a complicated manufacturing process is required to incorporate the shunt resistor into the integrated circuit. There is also a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art as described above, and there is no need to provide a separate shunt resistor, and a semiconductor integrated circuit capable of suppressing an increase in the resistance of the main current path. The purpose is to provide.

[0005]

Means for Solving the Problems In order to achieve the above object, the present invention is configured as described in the claims. That is, according to the first aspect of the present invention, a bonding wire, which is necessary when mounting a semiconductor chip, is used as a detection resistor of the overcurrent detection circuit. A bonding wire is a metal wire that connects a semiconductor chip and a connection portion of a mounting member (for example, a pad of a package) and has a small resistance value, but is connected to a main current path (for example, a power supply-external load-power transistor-ground). Since a large current flows, the voltage drop across the bonding wire connected to the path has a value that can be sufficiently detected by the comparator. Since the comparator has a large input impedance, almost no current flows.
Therefore, the voltage drop of the bonding wire connected to the comparator can be ignored. Therefore, the current flowing in the main current path can be accurately detected. With the above configuration, it is not necessary to newly insert a shunt resistor in series with the main current path, so that the on-resistance of the entire semiconductor integrated circuit does not increase and a complicated manufacturing process is required. The problem can be solved, and the area of the integrated circuit can be reduced by the shunt resistance.

[0006] The invention described in claim 2 is the invention according to claim 1.
In addition to the first bonding wire connecting the first main terminal of the two main terminals of the power transistor and the connection portion of the mounting member,
A second bonding wire for separately connecting the power supply terminal of the control means and the connection portion of the mounting member is provided separately. The two main terminals of the power transistor correspond to, for example, a collector and an emitter in a bipolar transistor and a drain and a source in a MOS transistor. Further, the first main terminal can be any of the above two main terminals. This configuration corresponds to, for example, an embodiment shown in FIGS.

According to a third aspect of the present invention, in addition to the first and second two bonding wires, a third bonding wire having one end connected to a connection portion of the mounting member is provided. The potential of the difference between the potential of the other end of the bonding wire and the potential of the first bonding wire on the side of the power transistor is detected as a potential difference for overcurrent detection. This configuration corresponds to, for example, an embodiment shown in FIGS. 3, 4, and 6 described later. With this configuration, since substantially no current flows through the third bonding wire, the potential difference for overcurrent detection can always be accurately detected regardless of the current consumption of the control means.

According to a fourth aspect of the present invention, there is provided a monitoring transistor through which 1 / N of the current flowing through the power transistor flows, and a first main terminal of the two main terminals of the monitoring transistor. A so-called mirror circuit is provided by providing a fourth bonding wire for connecting the connection portion of the mounting member. This configuration corresponds to, for example, an embodiment shown in FIGS. 5 and 6 described later. With this configuration, the degree of freedom in designing the overcurrent detection current value can be increased, so that the overcurrent detection current value can be designed with high accuracy that is not significantly affected by manufacturing variations and the like.

[0009]

As described above, according to the present invention, a bonding wire, which is always necessary when a semiconductor chip is to be mounted, is used as a detection resistor of an overcurrent detection circuit. Since it is not necessary to insert a shunt resistor in series, it is possible to solve the problem that the on-resistance of the entire semiconductor integrated circuit is increased. This eliminates the need for the shunt resistor and reduces the area of the integrated circuit by the shunt resistance.

According to the third aspect of the present invention, in addition to the above effect, an effect is obtained that the potential difference for overcurrent detection can always be accurately detected regardless of the current consumption of the control means. According to the fourth aspect, the degree of freedom in designing the overcurrent detection current value can be increased, so that the overcurrent detection current value can be designed with high accuracy that is not significantly affected by manufacturing variations and the like. The effect is obtained.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 is a circuit diagram showing a first embodiment of a semiconductor integrated circuit provided with an overcurrent detection circuit in a power transistor according to the present invention. First, the configuration will be described. A portion 301 surrounded by a broken line indicates a package mounting range of the semiconductor integrated circuit. Part 3 surrounded by a broken line
Reference numeral 02 denotes a semiconductor chip portion of a semiconductor integrated circuit in which the power transistor 100 and the processing circuit 303 are integrated.
The processing circuit 303 (portion surrounded by a broken line) includes the control circuit 30
4 and a comparison circuit 305 and a reference voltage circuit 306. 308 to 312 are the semiconductor chips 30 respectively.
2, bonding pads 313 to 316 are bonding pads of the package. 317
321 are bonding pads 308 to 312 of the semiconductor chip and bonding pads 3 of the package, respectively.
13 to 316.
Reference numeral 330 denotes an external load driven by the power transistor 100.

Next, the operation will be described. During normal operation, the power transistor 100 is turned on and off by the control circuit 304 according to the signal of the input terminal 310, and drives the external load 330. In addition, the power transistor 100
The comparison circuit 305 compares the potential difference between both ends of the bonding wire 317 connected to the source terminal of the reference voltage circuit and the reference voltage of the reference voltage circuit 306. When an abnormality occurs, for example, the external load 330 is short-circuited.
00, an overcurrent flows through the bonding wire 3
The comparison circuit 305 detects that the potential difference between both ends of the terminal 17 becomes larger than the reference voltage, and the control circuit 304 turns off the power transistor 100 irrespective of the signal of the input terminal 310, and the power transistor 100 Failure such as burning of the bonding wires 317 and 321 is prevented.

As described above, the bonding wire 317
Are detection resistors for detecting overcurrent. That is, the grounding pad 309 of the processing circuit 303 is connected to the bonding pad 313 of the package by the bonding wire 318 provided separately from the bonding wire 317 for the power transistor 100.
The current flowing from the processing circuit 303 via the bonding wire 318 is significantly smaller than the current flowing from the power transistor 100 via the bonding wire 317. For example, the current flowing through the bonding wire 317 is about several A to several tens A, whereas the current flowing through the bonding wire 318 is generally about several mA. Therefore, while the potential difference between both ends of the bonding wire 317 is several hundred mV, the potential difference between both ends of the bonding wire 318 is about 1/1000 of the potential difference, and the error due to this is negligible.

For example, when three Au wires each having a diameter of 38 μm and a length of 3 mm are formed in parallel as the bonding wires 317, the resistance value is 21 mΩ, and when the overcurrent detection current value is 10 A, the reference voltage is The value may be set to 0.21V. At this time, since the input impedance of the comparison circuit 305 is extremely large, the current flowing through the bonding wire 318 for the processing circuit is generally several mA, so that the error due to the potential difference generated at both ends of the bonding wire 318 can be ignored.

If the reference voltage circuit 306 is designed to have a temperature coefficient in consideration of the temperature coefficient of the resistance of the bonding wire 317, the temperature characteristic of the overcurrent detection current value can be compensated. As described above, according to the semiconductor integrated circuit including the overcurrent detection circuit in the power transistor according to the present invention, the bonding wire that is necessarily required when mounting the semiconductor chip is used as the detection resistor of the overcurrent detection circuit. With this configuration, it is not necessary to newly insert a shunt resistor for detection in series, so that the problem that the on-resistance of the entire semiconductor integrated circuit becomes high can be solved. Since there is no need to incorporate an integrated circuit, complicated manufacturing steps are not required, and the area of the integrated circuit can be reduced by the amount of the shunt resistor. .

FIG. 2 is a circuit diagram showing a more specific configuration of the circuit of FIG. Note that only electrically significant bonding wires are shown. Also, the description will be made on the assumption that the connections other than the bonding wires 106 and 107 shown in the form of resistors have no effective electrical resistance.

In FIG. 2, reference numeral 100 denotes a power transistor, and 101 denotes a solenoid (330 in FIG. 1) serving as an external load.
, 102 are signal input terminals (corresponding to 310), 1
03 is an AND circuit (corresponding to 304); 104 is a comparator (corresponding to 305); 105 is a reference voltage circuit (corresponding to 306); 106 is a bonding wire (corresponding to 317) through which the current of the power transistor 100 flows; This is a bonding wire (equivalent to 318) through which the current of the processing circuit flows.

In the circuit shown in FIG. 2, the potential of the bonding wire 106 on the power transistor 100 side (potential difference between both ends of the bonding wire 106) and the reference voltage circuit 105
Is compared with the reference voltage by the comparator 104. When the potential of the bonding wire 106 becomes higher than the reference voltage, the comparator 104
Becomes "Low", and the output of the AND circuit 103 becomes "Low" regardless of the input signal of the input terminal 102. Therefore, the power transistor 100 is turned off, and a failure due to an overcurrent can be prevented. Here, since the input impedance of the comparator 105 is extremely high, the current flowing through the bonding wire 107 on the processing circuit side is very small, and therefore, the error due to this resistance is negligible.

(Second Embodiment) FIG. 3 is a circuit diagram showing a second embodiment of a semiconductor integrated circuit provided with an overcurrent detection circuit in a power transistor according to the present invention. Second
The second embodiment differs from the first embodiment in the configuration and operation of the third embodiment in that a bonding pad 401 and a bonding wire 402 of a semiconductor chip 302 are added, and the potential of a ground bonding pad 313 of a package 301 is reduced. 302, and a difference voltage between the potential of the bonding wire 317 on the power transistor side (the potential of the bonding pad 308) and the potential of the bonding pad 313 input from the bonding pad 401 is compared with a reference voltage. It is.

The effect obtained in the first embodiment is the second effect.
In the embodiment described above, the same can be obtained. Second
The embodiment has the following operation and effect.

In the first embodiment, the current consumed by the processing circuit flows through the bonding wire 318, and a potential difference occurs between both ends. As described above, the error due to the potential difference is generally negligible, but in the second embodiment, the error due to the current flowing through the bonding wire 318 is eliminated, and more accurate overcurrent detection is performed. It was done. That is, the bonding wire 402
Since substantially no current flows through the bonding pad 401, there is no potential difference between both ends, and the potential input from the bonding pad 401 matches the potential of the bonding pad 313. Therefore, this value and the bonding wire 317
By calculating the potential difference from the power transistor side potential of
The potential difference between both ends of the bonding wire 317 can be accurately detected, and regardless of the potential difference generated between both ends of the bonding wire 318 due to current consumption of the processing circuit.
Overcurrent detection can be performed accurately.

Although FIG. 3 shows that the potential of the bonding wire 317 on the power transistor side and the potential of the bonding pad 313 input from the bonding pad 401 are directly input to the comparison circuit 305, in practice, As described later with reference to FIG. 4, the potential difference between the two potentials is obtained using a differential amplifier or the like, and is input to the comparison circuit 305.

FIG. 4 is a circuit diagram showing a more specific configuration of the circuit of FIG. Note that only electrically significant bonding wires are shown. Also, the description will be made on the assumption that the connections other than the bonding wires 106, 107, and 108 shown in the form of resistors have no effective electrical resistance.

In FIG. 4, reference numeral 108 denotes a bonding wire (40 in FIG. 3) connected to a ground pad of the package.
Reference numeral 109 denotes a differential amplifier (corresponding to a part of 305 in FIG. 3). The differential amplifier 109 includes, for example, an operational amplifier and a resistor. The differential amplifier detects the difference between the potential of the bonding wire 106 on the power transistor 100 side and the potential of the bonding wire 108,
This is supplied to a comparator 104 and compared with a reference voltage. Here, since substantially no current flows through the bonding wire 108, there is no potential difference between both ends. Therefore, by calculating the difference between this potential and the potential of the bonding wire 106 on the power transistor 100 side, the potential difference generated at both ends of the bonding wire 106 by the current flowing through the power transistor 100 can be accurately detected. And this relationship is bonding wire 1
07 is not affected by the current consumption of the processing circuit flowing through
Accurate overcurrent detection can be performed regardless of the current consumption of the processing circuit.

In the above description, an example in which a bonding wire connected to the source terminal of the power transistor is used as the detection resistor has been described. However, the bonding wire 321 on the drain terminal side may be used as the detection resistor. Absent.

Further, the semiconductor integrated circuit has been described by using one power transistor and one processing circuit, but a plurality of power transistors and processing circuits may be integrated. Further, although an example using a field effect transistor as the power transistor has been described, other power transistor devices such as a bipolar transistor may be used. Further, although an example is shown in which the semiconductor integrated circuit is packaged, it may be mounted in a pair chip. In any case, the configuration may be such that the bonding wire connecting the terminal of the power transistor through which the main current flows and the connection portion of the mounting member is used as the detection resistor.

(Third Embodiment) FIG. 5 is a circuit diagram showing a third embodiment of a semiconductor integrated circuit having a power transistor and an overcurrent detection circuit according to the present invention. Third
The difference between the configuration of the second embodiment and the first embodiment is that the power transistor 100 is replaced with a monitoring power transistor 5 having an area ratio of 1: N.
02 and a main power transistor 501, a source bonding pad 503 and a bonding wire 504 of the monitor power transistor 502 are added, and the source potential of the monitor power transistor 502 (the potential of the bonding wire 504 on the monitor power transistor side) is increased. The difference is that the comparison circuit 305 is configured to compare with the reference voltage.

Next, the operation will be described. In this circuit, 1 / N of the current flowing through the main power transistor 501 flows through the monitoring power transistor 502. The comparison circuit 305 detects that the potential generated on the bonding wire 504 by the 1 / N current becomes higher than a predetermined reference voltage. Other operations are the same as those in FIG.

The effect obtained in the first embodiment is as follows.
The same can be obtained in the third embodiment. Further, in the third embodiment, a monitoring power transistor 502 through which 1 / N of the current flowing through the main power transistor 501 flows is provided, and the potential of a bonding wire connected to the monitoring power transistor 502 is determined as a detection potential. Therefore, the degree of freedom in designing the overcurrent detection current value can be increased. That is, in the first embodiment, when designing the overcurrent detection current value,
The diameter and length of the bonding wire 317 are almost determined by the layout of the power transistor 100 and the value of the flowing current. Therefore, the only way to set the overcurrent detection value is to adjust the reference voltage value. In this regard, in the third embodiment, when designing the overcurrent detection current value,
Since the area ratio of the monitor power transistor 502 to the main power transistor 501 is 1: N and the layout of the monitor power transistor 502 is flexible, the diameter and length of the bonding wire 504 can also be used as design parameters. .

In the above configuration, since the degree of freedom in designing the overcurrent detection current value can be increased, the overcurrent detection current value can be designed with high accuracy which is not significantly affected by manufacturing variations and the like. The effect is obtained.

(Fourth Embodiment) FIG. 6 is a circuit diagram showing a fourth embodiment of a semiconductor integrated circuit provided with an overcurrent detection circuit in a power transistor according to the present invention. The configuration and operation of the fourth embodiment are obtained by combining the second embodiment and the third embodiment. In the fourth embodiment, both effects obtained in the second embodiment and the third embodiment can be obtained.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a more specific circuit diagram of the first embodiment.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention.

FIG. 4 is a more specific circuit diagram of the second embodiment.

FIG. 5 is a circuit diagram showing a third embodiment of the present invention.

FIG. 6 is a circuit diagram showing a fourth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 100 ... Power transistor 101 ... Solenoid used as an external load 102 ... Signal input terminal 103 ... AND circuit 104 ... Comparator 105 ... Reference voltage circuit 106 ... Bonding wire through which the current of the power transistor 100 flows 107 ... Bonding wire through which the current of the processing circuit flows Reference numeral 108: bonding wire connected to the ground pad of the package 109: differential amplifier 301: package mounting range of the semiconductor integrated circuit 302: semiconductor chip of the semiconductor integrated circuit 303: processing circuit 304 ... control circuit 305 ... comparison circuit 306: reference Voltage circuits 308 to 312, 401, 503: bonding pads of semiconductor chips 313 to 316, bonding pads of packages 317 to 321, 402, 504, bonding wires 330, external loads 501, In power transistor 502 ... monitor transistor

Claims (4)

[Claims] 1. A power transistor for driving an external load, a detection resistor through which a current flowing in the power transistor or a current proportional thereto is detected, and a potential difference between both ends of the detection resistor is detected. And control means for turning off the power transistor when the value becomes equal to or more than the value of the semiconductor integrated circuit, wherein, as the detection resistor, a connection portion between a semiconductor chip on which the semiconductor integrated circuit is formed and a mounting member; A semiconductor integrated circuit characterized by using a bonding wire for connecting the semiconductor integrated circuit. A first bonding wire for connecting a first main terminal of the two main terminals of the power transistor to a connection portion of the mounting member; a power supply terminal of the control means; A second bonding wire for connecting to the connection portion is provided separately, and a potential difference between a potential of the first bonding wire on the side of the first main terminal of the power transistor and a potential of the connection portion of the mounting member. The semiconductor integrated circuit according to claim 1, wherein the semiconductor integrated circuit is configured to detect 3. A third bonding wire, one end of which is connected to a connection portion of the mounting member, in addition to the first and second bonding wires, and the other end of the third bonding wire is provided. The apparatus according to claim 1, wherein a potential difference between a potential and a potential of an end portion of the first bonding wire on the first main terminal side of the power transistor is detected as the potential difference for detecting the overcurrent. Item 3. A semiconductor integrated circuit according to item 2. 4. The power transistor according to claim 1, wherein
/ N, and a fourth bonding wire for connecting the first main terminal of the two main terminals of the monitoring transistor to the connection portion of the mounting member, and 4. The semiconductor integrated circuit according to claim 1, wherein said bonding wire is used as said detection resistor.