JPH0774315A - Switching device - Google Patents

Abstract

PURPOSE:To facilitate mounting on a heat-radiating member and a printed board, and also to miniaturize a switching power supply. CONSTITUTION:A MOSFET 2 of a multisource and a control circuit block, which is used for PWM driving of the MOSFET 2, are housed in the package 1 of an integrated circuit. The above-mentioned control circuit block is composed of a reference voltage circuit 3, a low voltage malfunction preventing circuit 4, a gate 5, an abnormal heat detection circuit 6, an oscillation circuit 7, a latch circuit 8, a comparator 9 and the like. A power supply input terminal IN, the drain terminal D of the MOSFET 2, and three terminals of a source terminal S are provided outside the package 1 as external terminals. As a result, a switching device is composed of three terminals in the same manner as the MOSFET, and the number of externally attached parts can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching device device, and more particularly to a switching device device used as a switch element of a switching power supply.

[0002]

2. Description of the Related Art In recent years, in order to reduce the number of parts of a switching power supply, improve the space factor, downsize, and reduce the cost, an M which is used as a switching element.
A switching device device in which an OSFET and its control circuit are configured as a semiconductor integrated circuit on the same chip has been put into practical use.

Generally, a MOSFET used as a switching element of a switching power supply is mounted on a heat radiation member such as a heat sink to radiate heat generated by resistance loss during conduction and heat generated by switching, and suppresses temperature rise of a chip sufficiently. To ensure high reliability. Therefore, even in a switching device device in which the MOSFET and its control circuit are configured as a semiconductor integrated circuit of the same chip, it is desirable to attach it to a heat dissipation member such as a heat sink in order to ensure sufficient reliability.

[0004]

However, such a conventional switching device device is provided with, for example, 20 or more multi-pins as external terminals, and its heat radiation portion has a peculiar shape. For this reason, it is very difficult to mount it on the printed wiring board as well as mounting it on the heat dissipation member, and in particular, it is extremely difficult to automate the component mounting.

Further, since the number of external parts increases in proportion to the number of pins provided as external terminals, it is necessary to secure a space for mounting these external parts when a switching power supply is constructed. However, there is also a problem that the space factor is reduced and the size is restricted. The present invention solves such a problem, and an object thereof is to facilitate mounting on a heat dissipation member or a printed wiring board, and to reduce the size of a switching power supply by greatly improving a space factor. It is to realize the device unit.

[0006]

According to the present invention, in order to solve such a problem, an MO used as a switch element is provided.
In a switching device device in which an SFET and its control circuit are configured as a semiconductor integrated circuit on the same chip, a drain terminal and a source terminal of the MOSFET and a power supply input terminal of the control circuit are provided as external terminals.

[0007]

The switching device apparatus of the present invention is the same as the conventional M
It is configured as a 3-terminal element similar to the OSFET, and can be housed in a 3-terminal package similar to the conventional 3-terminal MOSFET. The switching device device thus configured is used as a switch element of a switching power supply and a control circuit of the switch element. Then, when the switching power supply is configured, the power supply to the respective internal parts of the switching device device is performed via the power supply input terminal of the control circuit.

In assembling the switching power supply, mounting on a heat dissipation member or a printed wiring board requires a conventional 3-terminal MO.
It can be easily performed in the same manner as the SFET. Further, since it has a three-terminal structure, the number of external parts can be greatly reduced, the space factor can be greatly improved, and the switching power supply can be downsized.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of an embodiment of the present invention. In FIG. 1, 1 is a package of an integrated circuit having a three-terminal structure,
A multi-source MOSFET 2 and a control circuit block for PWM driving the MOSFET 2 are configured and housed as a semiconductor integrated circuit on the same chip. As the external terminals, three terminals are provided: a power supply input terminal IN, a drain terminal D connected to the drain of the MOSFET 2, and a source terminal S connected to the source of the MOSFET 2. For example, TO220 is used as such a package.

Reference numeral 3 is a reference voltage circuit that provides a target value for voltage control and generates a bias current and a bias voltage for the internal circuit. 4 is a low voltage malfunction prevention circuit,
It is provided to prevent malfunction when the power supply input voltage is low. The output signal of the low voltage malfunction prevention circuit 4 is
If the input power supply voltage is lower than a certain threshold, MOSFE
It is input to one of the input terminals of the gate 5 having three input terminals so as to stop the output of the PWM signal for driving T2. Further, normally, the circuit 4 is provided with hysteresis in order to stabilize the operation.

An abnormal heating detection circuit 6 detects an abnormal temperature rise of the chip for chip protection. The output signal of the abnormal heating detection circuit 6 is also input to one of the input terminals of the gate 5 having three input terminals so as to stop the output of the PWM signal for driving the MOSFET 2 when the detected temperature exceeds the set value. ing. 7 is an oscillator circuit, P
The WM synchronization signal is output to the latch circuit 8 and P
A sawtooth wave or a triangular wave for generating the WM signal is input to the non-inverting input terminal of the comparator 9.

The output terminal Q of the latch circuit 8 is connected to the other input terminal of the gate 5. The output terminal of the gate 5 is connected to the gate terminal of the MOSFET 2 via the buffer amplifier 10. An error amplifier 11 amplifies an error between the power supply input voltage and the reference voltage and inputs it to one of the inverting input terminals of the comparator 9. The error amplifier 11 determines the input level of the comparator 9 so that the error between the power supply input voltage and the reference voltage becomes small, and has a built-in phase compensation circuit for compensating the frequency characteristic of the system.

Reference numeral 12 is a maximum duty setting circuit for setting the maximum pulse width of the PWM signal, and its output signal is inputted to the other inverting input terminal of the comparator 9. The output terminal of the comparator 9 is connected to one input terminal of the gate 13. The output terminal of the comparator 14 is connected to the other input terminal of the gate 13, and the output terminal of the gate 13 is connected to the reset terminal R of the latch circuit 8.

The comparator 14 detects a current proportional to the drain current detected from the multi-source of the MOSFET 2, and the detection current is input to the non-inverting input terminal and the threshold current I _th is input to the inverting input terminal. Has been done. When the detected current is equal to or _larger than the threshold current I _th , the comparator 14 limits the current for each pulse. That is, in the embodiment shown in FIG. 1, the MOSFET 2 is turned off by resetting the latch circuit 8.

FIG. 2 is a specific example of a switching power supply using the switching device device of FIG. In FIG. 2, the transformer T is provided with a primary winding W1, a secondary winding W2, and a bias winding WB. The positive terminal of the rectifier circuit REC is connected to one end of the primary winding W1.
At the other end of 1 is a switching device device package 1
Drain terminal D of is connected. The anode of the diode D1 is connected to one end of the secondary winding W2, and the capacitor C1 is connected to the cathode of the diode D1 and the other end of the secondary winding W2. One end of the bias winding WB is connected to the anode of the diode D1 and the diode D2 is connected.
Of the capacitor C and the other end of the bias winding WB
2 is connected. The diode D1 and the capacitor C1 and the diode D2 and the capacitor C2 form a rectifying and smoothing circuit, respectively.

Switching device package 1
Is connected to the other end of the bias winding WB and the negative terminal of the rectifier circuit REC. A capacitor C3 is connected between the positive terminal and the negative terminal of the rectifier circuit REC. The power supply input terminal IN of the package 1 of the switching device device is connected to the connection point of the diode D2 and the capacitor C2, and is also connected to the plus terminal of the rectifier circuit REC via the resistor R.

In the configuration of FIG. 2, when the input voltage is applied to the power supply input terminal IN, the control circuit block of the switching device device PWM-controls the MOSFET 2 so as to keep this input voltage constant. Here, since the input voltage is almost equal to the voltage normally generated in the bias winding WB, the rectifying / smoothing circuit of the secondary winding W2 is set by appropriately setting the winding ratio of the secondary winding W2 and the bias winding WB. To obtain the desired output voltage.

The circuit configuration of the switching device apparatus is not limited to that of the embodiment shown in FIG. 1, and the number of circuit elements can be increased or decreased according to the purpose, and at least the external terminals are accommodated in a three-terminal package. Just do it.

[0019]

As described in detail above, according to the present invention, a switching device device capable of output control can be constructed as a three-terminal element similar to a conventional MOSFET.
It can be housed in a 3-terminal package similar to a conventional 3-terminal MOSFET. The switching device device configured in this manner includes a switch element and a control circuit for the switch element, which are individual constituent elements of a conventional switching power supply.
It can be replaced by a device of one package of three terminals type similar to the conventional MOSFET used as a switch element.

As a result, when assembling the switching power supply, it can be easily mounted on the heat radiation member or the printed wiring board in the same manner as the MOSFET housed in the conventional three-terminal type package. In addition, since the package has a three-terminal structure, the number of external parts can be significantly reduced, the space factor can be greatly improved, and it is also effective for downsizing the switching power supply.

[Brief description of drawings]

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

FIG. 2 is a specific example diagram of a switching power supply using the switching device device of FIG.

[Explanation of symbols]

 1 package 2 MOSFET 3 reference voltage circuit 4 low voltage malfunction prevention circuit 5 gate 6 abnormal heating detection circuit 7 oscillation circuit 8 latch circuit 9 comparator 10 buffer amplifier 11 error amplifier 12 maximum duty setting circuit 13 gate 14 comparator

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H03K 17/00 A 9184-5J

Claims (1)

[Claims] 1. A switching device device in which a MOSFET used as a switch element and a control circuit thereof are configured as a semiconductor integrated circuit of the same chip, wherein a drain terminal and a source terminal of the MOSFET and a power input terminal of the control circuit are external terminals. A switching device device provided.