JPH04113664A - Semiconductor integrated circuit - Google Patents

Abstract

PURPOSE:To limit a collector current upon rising of the ambient temperature by connecting a resistor between a current detecting terminal of a semiconductor to be protected and a low potential power source, and connecting the base of a temperature sensitive transistor to the high potential side of the resistor. CONSTITUTION:A current detecting terminal 2 of an IGBT with CS (an insulated gate type bipolar transistor with a current detecting terminal) 1 is grounded through resistors 17, 18, and the base of a temperature sensitive transistor 8 is connected between the resistors 17 and 18, and connected to a reference voltage source 5 through a resistor 19. Thus, a current detector protecting circuit is coupled to a temperature sensitive protecting circuit to form a temperature current protecting circuit. The base of the transistor 8 is connected between the resistors 17 and 18 to limit its collector current in proportion to the temperature rise, and the IGBT 1 is not used over an available range.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a semiconductor protection circuit that protects, for example, an insulated gate electrode with a current detection terminal, a type bipolar transistor), and a transistor (IGBT) from supercurrent and temperature. .

[Conventional technology]

FIG. 3 is a configuration diagram of a conventional semiconductor protection circuit that protects an insulated gate bipolar transistor with a current detection terminal (hereinafter referred to as a C8-equipped IGBT) from temperature and current.

This semiconductor protection circuit is composed of a current detection protection circuit and a temperature detection protection circuit.
IGBT1 with S, current detection terminal 2 provided in this IGBTI with C8, resistor @3 connected to this current detection terminal 2, and one input terminal is connected between this resistor 3 and current detection terminal 2. a comparator 4, a reference voltage source 5 connected to the other input terminal of the comparator 4, and a three-person N0R whose input terminal is connected to the output terminal of the comparator 4.
1i path 6 and a gate driver amplifier 7 connected to the output end of this NOR circuit 6.

In addition, the temperature sensing protection circuit has a temperature sensing) - run disk 8,
A resistor 9 connected to the base of the temperature sensing transistor 8 with
, 10, a reference voltage source 5 connected to the resistor 10, a reference current source 11 and a diode 12 connected to the cap L/lid of the thermal transistor 8, and this diode 12.
transistor 13 whose base is connected to the cathode of transistor 13, and N whose input end is connected to the collector of this transistor 13.

It consists of an R circuit 6, a reference current source 14, and a gate driver up 7 connected to the output terminal of the NOR circuit 116.

This semiconductor protection circuit is designed so that when collector current Ic flows through IGBT 1 with CS, a shunt of collector current Ic flows to current detection terminal 2, and the shunt flows through resistor 11!3 to reach branch point 15. Potential increases. The potential of this branch point 15 and the voltage output from the reference voltage source 5 are compared by the conoparator 4, and as a result, the output voltage from the gate driver amplifier is stopped by the output of the NOR circuit 6, and the collector current Ic is blocked.

On the other hand, the temperature sensing transistor 8 has a base on-voltage V@I due to an increase in ambient temperature due to heat generation of the IGBT 10 with CS.
(OHl decreases linearly, on-voltage V 8
g +ON l is reference voltage #, 5, resistor 9 and resistor 1
It turns on when the potential decreases below the potential at the branch point 16, which is created with 0. Then, the current from the reference current source 11 starts to flow into the temperature sensing transistor 8 and no longer flows into the transistor 13 via the diode 12, so the transistor 13 is turned off, and the current from the current source 14 flows into the NOR circuit. 6, the output voltage from gate driver amplifier 7 to gate) is stopped, and IGBT 1 with C8
is turned off.

[Problem to be solved by the invention]

In the conventional semiconductor protection circuit as described above, the current detection protection circuit and temperature detection protection circuit were each independent, so protection could only be achieved under the conditions shown in the diagonally shaded area in Figure 4, and as shown in the dotted line area. In reality, unprotected areas occurred even under conditions that exceeded the usable range. That is, unless the collector current used in the C8-equipped IGBT 1 is limited as the ambient temperature rises, the C3-equipped IGBTI would exceed its usable range and be destroyed.

The present invention was made to eliminate the above-mentioned drawbacks, and an object of the present invention is to provide a semiconductor protection circuit in which the collector current is limited as the ambient temperature of the semiconductor increases.

[Means to solve the problem]

In the semiconductor protection circuit according to the present invention, a resistor is connected between a current detection terminal of a protected semiconductor and a low potential power source, and a base of a temperature sensitive transistor is connected to the high potential side of this resistor.

(Function) In this invention, when the current in the protected semiconductor exceeds a certain level, the current detection protection means turns off the protected semiconductor, and as the temperature rises, the thermal sensing transistor turns on. If the temperature-sensing transistor turns on, the temperature-sensing protection circuit turns the protected semiconductor off.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a semiconductor protection circuit of the present invention. In this figure, the same or equivalent parts as in FIG. 3 are given the same reference numerals.

In this embodiment, the current detection terminal 2 of the C3-attached IGBT 1 is grounded via resistors 17 and 18, and the base of the temperature sensing transistor 8 is connected between the resistor 17 and the resistor W18, and It is connected to the reference voltage source 5 via 19. That is, the current detection protection circuit and the temperature detection protection circuit are combined to form a temperature current protection circuit.

Temperature protection is not working, that is, the on-voltage of the temperature sensing transistor 8 v tt (os 1
is large and the surroundings of the IGBTI with C8 are at a certain temperature, the collector current Ie up to the current value obtained by dividing the difference between the on-voltage v at (as 1 and the potential of the branch point 16 by the resistance value of the resistor [18) If the ratio of the collector current Ic to the shunt current is 1000:1, the collector current Ic that can be passed can be expressed by the following equation.

Since the voltage V@g (as) in the above equation decreases in proportion to the temperature rise, the collector current Ic can be limited in proportion to the temperature rise.

In this way, in the semiconductor protection circuit of the present invention, the resistor N17
By connecting the base of the temperature sensing transistor 8 between the temperature sensing transistor 8 and the resistor 18, it is possible to limit the collector current in proportion to the temperature rise as shown in Fig. 2, and the usable range shown in Fig. 2 is The IGBTI with C8 will not be used for more than 30 minutes, and failures can be prevented.

〔Effect of the invention〕

As explained above, in this invention, a resistor is connected between the current detection terminal of the protected semiconductor and the low potential power supply, and the base of the temperature sensing transistor is connected to the high potential side of this resistor, so that it is proportional to the temperature rise. This has the effect of limiting the collector current, thereby making it possible to protect against failures due to use beyond the usable range.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing one embodiment of the present invention, and FIG.
The figure shows the area that can be protected by the circuit of the example.
FIG. 3 is a conventional circuit diagram, and FIG. 4 is a diagram showing an area that can be protected by the conventional circuit. In the figure, 1 is an IGBT with CS, 2 is a current detection terminal,
4 is a comparator, 5 is a reference voltage source, 6 is a NOR circuit,
7 is a gate driver amplifier, 8 is a temperature sensing transistor, 1
1.14 is a reference current source, 12 is a diode, 13 is a transistor, 15° and 16 are branch points, and 17, 18, and 19 are resistors. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent Masuo Oiwa (2 others) Fig. 1 Fig. 3 Fig. 2 fcs J size IGBTI collector 1 sake 9 To (I with C5
GBTInNIi To (CS I41GBTIslllil1m/l) Heisei

Claims (1)

[Claims] Current detection protection means controls the protected semiconductor to turn it off when the current flowing through the current detection terminal of the protected semiconductor exceeds a certain level, and the on-voltage of the base decreases as the ambient temperature rises. In the semiconductor protection circuit, the semiconductor protection circuit includes a temperature sensing protection circuit that controls the protected semiconductor to turn off the protected semiconductor when the thermal transistor is turned on. A semiconductor protection circuit characterized in that a resistor is connected between a detection terminal and a low potential power source, and a base of the temperature sensing transistor is connected to a high potential side of the resistor.