JP3190941B2 - Semiconductor integrated circuit device for insulated switching power supply device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor integrated circuit device for an insulated switching power supply.

[0002]

2. Description of the Related Art In recent years, downsizing of electronic equipment has been demanded, and power supplies have been downsized by using switching power supplies and increasing the switching frequency. Along with this, semiconductor devices used for power supply devices are also becoming highly integrated. An example of this is MOSFE
Developed a semiconductor integrated circuit device for an insulated switching power supply device in which a power switching element such as a T (for example, an N-channel MOSFET) or a bipolar transistor (for example, an NPN bipolar transistor) and its control circuit are mounted in one package. Have been.

[0003] In addition, the mounting method of the power switching element chip and its control circuit chip is different from that in which the power switching element chip and its control circuit chip are mounted on separate chips. Has been evolving to be mounted on the same chip. One example is the Proceeding of 1992 International Sympo
sium on Powersemiconductor Devices & ICs, Tokyo p
p.322-327 "A 1200V BiCMOS TECHNOLOGYAND ITS APPLIC
ATION "by Vladimir Rumennik Power Integrations, In
c. This is the power M
This is a so-called intelligent power MOSFET for a switching power supply in which an OSFET and its control circuit and protection circuit are mounted on one chip.

FIG. 3 is a schematic circuit diagram of an insulated switching power supply using the intelligent power MOSFET for switching power supply. In FIG. 3, reference numeral 43b denotes a semiconductor integrated circuit device for an insulated switching power supply device;
b is an AC power supply, 8b is a diode bridge, 9b is a smoothing capacitor, 10b is a secondary-side rectifying and smoothing circuit including a diode and a smoothing capacitor, 12b is a transformer for insulation, and 25b is a power switching element including an N-channel MOSFET. , 42b are control circuits for controlling the power switching element 25b, 38b is a parasitic inductance component, 35b is a low-voltage side wiring, and 36b is a control circuit 42.
b, a parasitic inductance component 41b,
4b is a power input wiring, 45b is a primary output wiring, 37b
Is a source lead terminal.

In this insulated switching power supply device, an AC voltage of an AC power supply 7b is rectified and smoothed by a diode bridge 8b and a smoothing capacitor 9b to obtain a DC voltage. The AC voltage is induced on the secondary side of the transformer 12b by intermittent switching by the switching element 25b, and the AC voltage is rectified and smoothed by the secondary side rectifying and smoothing circuit 10b to be a DC voltage. The power switching element 25b is controlled by the control circuit 42b.

When the above-mentioned semiconductor integrated circuit device 43b for an insulated switching power supply is mounted on a printed circuit board in an insulated switching power supply, the size of the insulated switching power supply must be minimized. It requires some ingenuity in designing the wiring pattern. However, in the design of the pattern wiring, a wiring to which a high voltage is applied, for example, a power input wiring 44 to which a DC voltage obtained by rectifying and smoothing the voltage of the AC power supply 7b in FIG.
b and power switching element 2 from transformer 12b
Primary output wiring 45b through which primary output current flows to 5b
In addition, it is necessary to make the distance between the low-voltage wiring, for example, the low-voltage wiring 35b on the primary side and the wiring on the secondary side a distance in compliance with the regulations, or in a line where a large current flows, the To minimize the occurrence of noise due to the inductance component of
It is necessary to increase the width as much as possible, or make the high-voltage wiring and the low-voltage wiring on the front and back of the printed circuit board, and apply the high-voltage side wiring to the low-voltage wiring due to the parasitic capacitance of the printed circuit board. It is necessary to avoid such wiring in order to prevent signals from being carried.

[0007]

In the semiconductor integrated circuit device 43b for the insulated switching power supply device provided on the primary side of the insulated switching power supply device shown in FIG. This is a path from the drain to the source of the MOSFET that is the power switching element 25b. Here, the source wire of the power switching element 25b has a parasitic inductance component 38b. The source lead terminal 37b of the semiconductor integrated circuit device 43b for the insulated switching power supply device also has a parasitic inductance component 41.
b exists.

The power switching element 25b has a structure shown in FIG.
A current 39b flows as shown in FIG. 4A, and at the beginning and end of the flow, the parasitic inductance components 38b and 41b cause the voltage 4b as shown in FIG.
0b is generated. As a result, the potential is transiently different in the ground portion inside the semiconductor integrated circuit device 43b for the insulated switching power supply device. That is, the ground portion (source) of the power switching element 25b and the ground 36b of the control circuit 42b have different potentials depending on the voltages generated by the parasitic inductance components 38b and 41b of the ground line of the power switching element 25b.

Then, the ground 36 of the control circuit 42b is connected to the ground line of the power switching element 25b.
A transient current flows with respect to b, affecting the operation of the control circuit 42b. If this is severe, a malfunction will occur. Such an effect is a problem commonly occurring in an integrated circuit device that handles a large current.However, when the integrated circuit device is used for a power supply, in the case of an integrated circuit device having a built-in high-voltage power switching element, the power The specific resistance of the semiconductor substrate on which the switching element is formed is high, and the voltage generated by this transient current becomes large, so that the semiconductor substrate is easily affected.

Accordingly, an object of the present invention is to provide a semiconductor integrated circuit device for an insulated switching power supply device which can prevent a malfunction of a control circuit due to a transient current flowing to the ground through a power switching element. .

[0011]

According to a first aspect of the present invention, there is provided a semiconductor integrated circuit device for an insulated switching power supply, which controls a power switching element which is a part of the insulated switching power supply, and the power switching element. The control circuit and the control circuit are mounted in one package, and the ground electrode of the power switching element is connected to two or more first electrodes in the package.
The first package lead is electrically connected to the package lead, and the ground electrode of the control circuit is electrically connected to a second package lead different from the first package lead in the package, and a part of the first package lead and the second package lead are connected. Electrical connection is made outside the package using, for example, a printed circuit board, and the rest of the first package lead is electrically connected to the ground line of the insulated switching power supply.

According to a second aspect of the present invention, there is provided a semiconductor integrated circuit device for an isolated switching power supply, wherein the isolated switching power supply according to the first aspect is a flyback type. Claim 3
According to the semiconductor integrated circuit device for an insulated switching power supply device described above, the insulated switching power supply device in claim 1 is of a feedforward type.

[0013]

According to the present invention, of the power switching element mounted on one package and the control circuit thereof,
A ground electrode of the power switching element is electrically connected to two or more first package leads via a wire in the package. The ground electrode of the control circuit is electrically connected to a second package lead different from the first package lead in the package via a wire. Then, a part of the first package lead and the second package lead are electrically connected outside the package. As a result, only the current of the control circuit flows through the connection line between the ground electrode of the control circuit and the ground electrode of the power switching element, but this current is an extremely small current and an almost steady current. Therefore, there is almost no voltage generation due to the parasitic inductance component of the connection line between the ground electrode of the control circuit and the ground electrode of the power switching element. Therefore, the potential of the connection line between the ground electrode of the control circuit and the ground electrode of the power switching element and the potential of the ground electrode of the control circuit are substantially the same as the ground electrode of the power switching element.

On the other hand, all of the remaining first package leads are electrically connected to the ground line of the insulated switching power supply. As a result, an output current flowing through the power switching element flows through a connection line connecting the ground electrode of the power switching element and the ground line of the insulated switching power supply device. Therefore, since a parasitic inductance component exists in the connection line connecting the ground electrode of the power switching element and the ground line of the insulated switching power supply, when the power switching element switches, the voltage due to the parasitic inductance component is reduced. appear. However, with reference to the ground electrode of the power switching element, the ground electrode of the control circuit is not affected by the voltage generated in the parasitic inductance component. That is, due to the switching of the power switching element, the ground electrode of the power switching element fluctuates when viewed from the ground line of the insulated switching power supply device, but the potential of the ground electrode of the control circuit changes the potential of the power switching element. Since the voltage changes in conjunction with the ground electrode, no current flows between the ground electrode of the control circuit and the ground electrode of the power switching element. Normal operation is performed with reference to the potential of the ground electrode. Therefore, the control circuit is not affected by the parasitic inductance component described above, and does not malfunction.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An insulation type switching power supply including a semiconductor integrated circuit device for an insulation type switching power supply according to an embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic view of an insulated switching power supply device according to an embodiment of the present invention, including a method of connecting electrodes and package leads thereof, including a semiconductor integrated circuit device for an insulated switching power supply device used therein. showed that. FIG. 2 is a diagram showing a semiconductor integrated circuit device for an insulated switching power supply in detail. Here, an embodiment of the present invention will be described with reference to FIGS.

First, FIG. 1 will be described. FIG. 1 shows an insulated switching power supply, which includes an insulated switching power supply semiconductor integrated circuit device 5 that can be directly started from a voltage obtained by rectifying and smoothing an AC power supply 7 with a diode bridge 8 and a smoothing capacitor 9. . The semiconductor integrated circuit device 5 for an insulated switching power supply device has a power MOSFET 1 serving as an output power switching element and a control circuit 2 in a single chip. Flat package 5
A. Inside the package 5A, the source electrodes 3 to 3 of the power MOSFET 1
Gold wires were struck on the package leads 12 and 21,
Gold wires are struck from the drain electrode 4 to two package leads. As for the control circuit 2, the control circuit 2
Each gold wire is connected to a different package lead from the bonding pad of each part.

The package leads of the control circuit 2 include external components necessary for the operation of the control circuit 2, such as a reference resistor 20 for determining a reference constant current in the circuit, a capacitor 19 for determining the oscillation frequency of the oscillator, and an internal component. A capacitor 18 for a stabilized power supply serving as a power supply for the control circuit, a capacitor 17 for determining a period of the intermittent oscillation when the power MOSFET 1 performs an intermittent oscillation when the secondary side is overloaded, and a load on the secondary side A photocoupler 14 for controlling the on-duty of the power MOSFET 1 according to the situation is connected.

The ground package lead 16 of the control circuit 5 is connected to the source 3 of the power MOSFET 1.
One of the package leads 21 is connected to a wiring pattern outside the semiconductor device. The other package lead 12 of the power MOSFET 1 is connected to the ground package lead 1 of the control circuit 2.
6 is not connected by a wiring pattern, but is directly connected to the ground of the insulated switching power supply.

Reference numeral 36 denotes a transformer, 10 denotes a secondary side rectifying / smoothing circuit, and 11 denotes an auxiliary winding rectifying / smoothing circuit. Numeral 34 is a secondary side overvoltage detecting circuit, which has a built-in photocoupler transmitter, and 6 is a photocoupler receiver. Reference numeral 15 denotes an on-duty control circuit, which includes voltage dividing resistors 13d and 13e, an on-duty control operational amplifier 13, and the like.

In the semiconductor integrated circuit device for an insulated switching power supply having the above configuration, one package 5
A of the power MOSFET 1 and its control circuit 2 mounted on the power MOSFET A, the source electrode (ground electrode) 3 of the power MOSFET 1 is electrically connected to two or more first package leads 12 and 21 via wires in the package 5A. Connected. The ground electrode of the control circuit 2 is electrically connected to a second package lead 16 different from the first package lead via a wire in the package 5A. Then, a part 21 of the first package lead and the second package lead 16 are electrically connected outside the package 5A. As a result, only the current of the control circuit 2 flows through the connection line between the ground electrode of the control circuit 2 and the source electrode 3 of the power MOSFET 1, but this current is an extremely small current, and the current is almost constant. Therefore, the ground electrode of the control circuit 2 and the power MOSF
There is almost no voltage generation due to the parasitic inductance component of the connection line between the ET1 and the source electrode 3. Therefore, the ground electrode of the control circuit 2 and the power MOSF
The potential of the connection line with the source electrode 3 of the ET1 and the potential of the ground electrode of the control circuit 2 are
It has substantially the same potential as the source electrode 3 of ET1.

On the other hand, all the remaining 12 of the first package leads are electrically connected to the ground line of the insulated switching power supply. As a result, the power MOSFET
A power MOSF is connected to a connection line connecting the source electrode 3 and the ground line of the insulated switching power supply.
The output current flowing to ET1 flows. Therefore, since a parasitic inductance component exists in the connection line connecting the source electrode 3 of the power MOSFET 1 and the ground line of the insulated switching power supply, the power MOSFET
When the ET1 switches, a voltage is generated due to the parasitic inductance component. However, power MOSFET
With reference to one source electrode 3, the ground electrode of the control circuit 2 is not affected by the voltage generated in the parasitic inductance component. That is, by the switching of the power MOSFET 1, the source electrode 3 of the power MOSFET 1
Although the voltage fluctuates when viewed from the ground line of the insulated switching power supply, the potential of the ground electrode of the control circuit 2 changes in conjunction with the source electrode 3 of the power MOSFET 1. For M
No current flows between the source electrode of the OSFET 1 and the primary circuit of the isolated switching power supply device operates normally with reference to the potential of the source electrode 3 of the power MOSFET 1. Therefore, the control circuit 2 is not affected by the parasitic inductance component described above, and does not malfunction. The basic operation is the same as the conventional example.

Next, FIG. 2 will be described. Semiconductor integrated circuit device 5 for an insulation type switching power supply device shown in FIG.
The high voltage on the primary side obtained by rectifying and smoothing the AC power supply 7 with the diode bridge 8 and the smoothing capacitor 9 and the auxiliary winding voltage of the transformer 36 can be applied through the auxiliary winding rectifying and smoothing circuit 11. When the AC power supply 7 is started, the current of the circuit is supplied from the former, and when the voltage of the auxiliary winding is generated by this, the current is supplied from here and the supply current from the former is cut off.

In the semiconductor integrated circuit device 5 for an insulation type switching power supply device, the two rectifying and smoothing circuit portions (8, 9, 1) are provided.
The pre-regulator circuit 26 for generating a stabilized power supply voltage serving as a power supply for a control circuit inside the integrated circuit from 1), a band gap circuit 27 for generating a reference voltage of 1.25 V used in the internal circuit, and the input voltage on the primary side is a specified value. If it is too small or too large, it is detected and the power MOSFET 1
32, an overheat protection circuit 33 that stops the operation of the power MOSFET 1 when the temperature of the chip becomes 150 ° C. or higher, an oscillator 28 that determines the oscillation frequency of the power MOSFET 1, and an overload state on the secondary side. The timer circuit 30 makes the power MOSFET 1 perform an intermittent oscillation operation in which the period of the normal oscillation and the period in which the power MOSFET 1 is stopped are repeated, and the operation of the power MOSFET 1 when the voltage on the secondary side becomes higher than a specified value. Overvoltage protection circuit 35 for stopping power supply, on-duty control circuit 29 for controlling on-duty of power MOSFET 1, power MO
An overcurrent protection circuit 22 for a current flowing through the SFET 1;
A logic circuit 24 that drives the power MOSFET 1 by integrating the protection and control, and a power MOSFET
T1 is built in the semiconductor integrated circuit device 5 for the insulated switching power supply device shown in FIG. 31 is a stabilized power supply line.

In FIG. 2, 15 is an on-duty control circuit, 34 is a secondary side overvoltage detection circuit, 6 is a photocoupler light receiving section for receiving an output signal of the secondary side overvoltage detection circuit 34, and 14 is an on-state. It is a photocoupler light receiving unit that receives an output signal of the duty control circuit 15. Reference numeral 10 denotes a secondary-side rectifying / smoothing circuit, and reference numeral 13 denotes an on-duty control operational amplifier.

In the above-described embodiment, an example using a MOSFET as a power switching element has been described. However, the present invention is not limited to this, and an example using a bipolar transistor can be given as an example. Further, the power switching element and its control circuit may be formed on separate chips.
The circuit type of the insulated switching power supply device may be a feedforward type or a flyback type.

[0026]

According to the semiconductor integrated circuit device for an insulated switching power supply device of the present invention, the ground electrode of the power switching element is electrically connected to two or more first package leads in the package, and the control circuit Electrically connecting a ground electrode of the first package lead inside the package to a second package lead different from the first package lead, electrically connecting a part of the first package lead and the second package lead outside the package, Since the rest of the package leads were electrically connected to the ground line of the insulated switching power supply, even if the ground potential of the power switching element was affected by the current flowing through the ground electrode of the power switching element, the control circuit The ground potential of the power switching element and the ground electrode of It is possible to prevent a current from flowing between the ground electrode of the control circuit and the ground electrode of the power switching element, thereby preventing the control circuit from malfunctioning and reducing the operation of the isolated switching power supply. Can be stabilized.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an insulated switching power supply device incorporating a semiconductor integrated circuit device for the insulated switching power supply device.

FIG. 2 is a schematic diagram showing a specific configuration of a semiconductor integrated circuit device for an insulated switching power supply device.

FIG. 3 is a schematic diagram showing a conventional example of an insulated switching power supply device.

FIG. 4 is a waveform diagram illustrating a current flowing through a ground electrode of a power switching element and a waveform of a voltage of a ground portion generated by the current.

[Explanation of symbols]

Reference Signs List 1 power MOSFET 2 control circuit 3 source electrode 4 drain electrode 5 semiconductor integrated circuit device for insulated switching power supply device 5A package 6 photocoupler for detecting secondary overvoltage rise 7 AC power supply 8 diode bridge 9 smoothing capacitor 10 secondary Side rectification / smoothing circuit 11 Auxiliary winding rectification / smoothing circuit 12 Package lead 13 On-duty control operational amplifier 14 On-duty control photocoupler 15 On-duty control circuit 16 Package lead 17 Capacitor 18 Capacitor 19 Capacitor 20 Reference resistor 21 Package lead 22 Overcurrent protection Circuit 24 Logic circuit 26 Pre-regulator circuit 27 Band gap circuit 28 Oscillator 29 On-duty control circuit 30 Timer circuit 31 Stabilized power supply line 32 Under- and over-voltage protection Circuit 33 Overheat protection circuit 34 Secondary side overvoltage protection circuit 35 Secondary side overvoltage protection circuit 36 Transformer

Claims (3)

(57) [Claims] 1. A power switching element, which is a part of an insulated switching power supply device, and a control circuit for controlling the power switching element are mounted in one package, and a ground electrode of the power switching element is connected to a power supply. The package is electrically connected to two or more first package leads in the package, and a ground electrode of the control circuit is connected to a second electrode different from the first package lead in the package.
Electrically connecting to a package lead, electrically connecting a part of the first package lead and the second package lead outside the package, and connecting the rest of the first package lead to the insulation type switching power supply. A semiconductor integrated circuit device for an insulated switching power supply device electrically connected to a ground line. 2. The semiconductor integrated circuit device for an insulated switching power supply according to claim 1, wherein the insulated switching power supply is a flyback type. 3. The semiconductor integrated circuit device for an insulated switching power supply according to claim 1, wherein the insulated switching power supply is a feedforward type.