JPH1198834A - Semiconductor device for switching power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of external components, reduce a space for circuit configuration and reduce the manufacturing cost by forming an IC including a main switching element, an IC for controlling, and peripheral elements on one or two chips and assembling these chips into a single package, in a switching regulator. SOLUTION: An integrated circuit IC1 for controlling, a FET Q1 for main switching, transistors Q3 , Q4 , resistors R7 -R24 , capacitors C12 -C19 , diodes D9 -D14 , Zener diodes ZD1, ZD2, and a thyristor SCR1 are formed on a chip including a FET for main switching of a MOSFET with current sensor and a chip constituted of the integrated circuit IC1 for controlling including peripheral circuits. Then, these two chips are assembled into a single package. By this method, the number of external components can be reduced and a space for circuit configuration can also be reduced while the conventional circuit function is preserved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device for a switching power supply.

[0002]

2. Description of the Related Art FIG. 6 is a diagram showing a configuration of a conventional semiconductor device for a current control type switching power supply, and a control IC (I
C). Outside the control IC (IC), a phototransistor coupler IC2, a main switching FET (Q1), and a startup FET (Q2)
, Transistors Q3 and Q4, resistors R1 to R24,
Capacitors C1 to C19 and diodes D1 to D14
, Zener diodes ZD1 and ZD2, thyristor SCR1, and transformer T. Also, 1
00 is a rectifier circuit, and 101 is a reset switch.

FIG. 7 is a block diagram showing the configuration of the above-described control IC (IC). In FIG.
UVLO (under voltage lockout) 110 is a power supply Vcc
And a reference voltage, and when the difference is within a predetermined voltage range, an output is generated. The S / R bar 111 is a hold circuit that holds the output of the UVLO. Then, the internal constant voltage (5V REF) is output if the signal is held, and is not output otherwise. The VREF Good Logic 112 is a circuit for determining whether or not the above-mentioned internal constant voltage is output normally, and outputs an output when it is normal. Inte
rnal Bias 113 is a reference internal constant voltage. Osc
Reference numeral 114 denotes an oscillation circuit, and PWM Latch 115 denotes a latch circuit. Error Amp 116 is a voltage comparator,
An error output corresponding to the difference between the two inputs is output. Current Sens
e Comparator 117 is a current comparator that compares the error output of Error Amp with the current flowing through the output stage. Then, the current of the output stage is changed according to the error output. 118
Is an OR circuit. When all the inputs are at the low level, turning on the transistor 119 causes the Vc level to rise.
Output from Output.

[0004]

However, in the above-described conventional semiconductor device for a switching power supply, as can be seen from the above description, many elements including a main switching FET (Q1) are provided outside the control IC. The space on the circuit configuration increases,
There is a drawback that manufacturing costs increase.

The semiconductor device for a switching power supply of the present invention has been made in view of such a problem, and its object is to reduce the number of external components while obtaining the same function as that of the conventional semiconductor device. It is an object of the present invention to provide a switching power supply semiconductor device capable of reducing manufacturing cost while reducing space in a circuit configuration.

[0006]

In order to achieve the above object, a semiconductor device for a switching power supply according to a first aspect of the present invention includes a main switching element in a switching power supply, a control IC, and peripheral elements thereof. IC
It is made into two chips or one chip and assembled into a single package.

A semiconductor device for a switching power supply according to a second invention is the semiconductor device for a switching power supply according to the first invention, wherein the startup circuit, the PWM control circuit, the current limiting circuit, the overvoltage protection circuit, Includes a protection circuit for secondary side abnormalities and soft start.

The semiconductor device for a switching power supply according to a third aspect of the present invention is the semiconductor device for a switching power supply according to the first or second aspect of the present invention, wherein the magnitude of overvoltage of the overvoltage protection circuit and the secondary side abnormality The sequence of accepting the secondary side abnormality in the protection circuit and shutting off the startup is set by a timer circuit in the control IC.

Further, a semiconductor device for a switching power supply according to a fourth aspect of the present invention is the semiconductor device for a switching power supply according to the second or third aspect, wherein a soft start terminal and a secondary side abnormal input terminal are shared.

According to a fifth aspect of the present invention, in the semiconductor device for a switching power supply according to any one of the first to fourth aspects, the main switching element is a MOSFET.

Further, in a semiconductor device for a switching power supply according to a sixth invention, in the semiconductor device for a switching power supply according to any one of the first to fourth inventions, the main switching element is a sense MOSFET.

A semiconductor device for a switching power supply according to a seventh aspect of the present invention is the semiconductor device for a switching power supply according to any one of the first to sixth aspects, wherein the leading edge blanking (LEB) circuit and the heat protection are provided. And a circuit.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration of a semiconductor device for a switching power supply according to an embodiment of the present invention. As can be seen from a comparison with the configuration of the conventional semiconductor device for a current-controlled switching power supply shown in FIG. 6, this configuration has a control IC (IC), a main switching FET (Q1), and a transistor Q3 shown in FIG. , Q4,
Resistors R7 to R24, capacitors C12 to C19, diodes D9 to D14, a Zener diode ZD1,
ZD2 and thyristor SCR1 are two chips (main switching F as MOSFET with current sensing)
It is characterized by comprising a chip including an ET (Q1) and a control IC incorporating a peripheral circuit) into a single package IC1. The portion surrounded by the dotted line in FIG. 6 corresponds to the portion incorporated in the IC in the present embodiment.

The semiconductor device IC1 has eight external terminals, a reset (Reset), a start-up (Start up), a protect-in (Protect in), a current sense (CS),
Feedback (FB), power supply Vcc, ground GN
D and a drain are provided.

FIG. 2 shows the switching power supply semiconductor device as a control IC (IC) and a main switching FET.
FIG. 11 is a diagram showing a two-chip configuration including a MOSFET as (Q1) and incorporated in a single package. The order of the types of external terminals in FIG. 2 (Reset, St
art up, Protect in, ...) are described for convenience and need not be in this order.

FIG. 3 is a block diagram of the semiconductor device for a switching power supply according to the present invention.
(Q2) and the resistors R1 and R2 and the diode D1 connected thereto, and the phototransistor coupler IC connected to the protect-in terminal (secondary abnormal input terminal)
2 and the capacitor C7 are externally provided, but the other portions are configured as control ICs. The control IC includes a PWM control circuit 10, a start-up circuit 11, a current limiting circuit 12, an overvoltage protection circuit 13, a protection circuit 14 for secondary (load) side abnormality, and a soft start 15.
As a function.

The magnitude of the overvoltage of the overvoltage protection circuit 13, the sequence of accepting the secondary side abnormality in the secondary side abnormality protection circuit 14, and shutting off the startup are determined by timer circuits 16 and 17 in the control IC. Is set.
In addition, a soft start terminal and a secondary side abnormal input terminal
Shared with Protect in.

FIG. 4 is a time chart showing a start-up sequence of each unit.
(2) Start-up of the startup FET (Q2),
(3) Internal power supply (Vref) ON, (4) Shutdown of startup FET (Q2), (5) Overvoltage protection ON (Overvoltage setting), (6) Soft start (Charging of capacitor C7), (7) Secondary Receiving a side protection error (Protect
in) has a starting sequence.

FIG. 5 is a diagram showing a modification of the configuration shown in FIG. In this modification, the switching FET of FIG.
Using a sense MOSFET (Q1 ′) as (Q1),
A leading edge blanking (LEB) circuit 18 is added between the CS terminal and the current limiting circuit 12, and a heating protection circuit 20 is added as one of the inputs to the OR circuit 19. The leading edge blanking (LEB) circuit 18 and the heating protection circuit 20 may be provided in the configuration of FIG.

[0020]

According to the present invention, the main switching element, the control IC, and their peripheral elements are made into two chips or one chip and incorporated in a single package. It is possible to reduce the number of external parts while obtaining the function, thereby reducing the manufacturing cost while reducing the space in the circuit configuration.

In addition, overvoltage setting, secondary side abnormality reception,
Since the start-up circuit cut-off sequence is set by the timer circuit, the circuit design on the user side becomes easy and a stable system can be supplied.

Further, since the soft start terminal and the secondary side abnormal input terminal are shared, the number of package terminals is reduced, so that the size of the package can be reduced and the number of external components can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a semiconductor device for a switching power supply according to an embodiment of the present invention.

FIG. 2 is an IC for controlling the switching power supply semiconductor device.
And MOSFET as main switching FET
FIG. 4 is a diagram showing a two-chip configuration made up of a single package.

FIG. 3 is a block diagram of the semiconductor device for a switching power supply.

FIG. 4 is a time chart showing a startup sequence of each unit.

FIG. 5 is a diagram showing a modification of the configuration shown in FIG. 3;

FIG. 6 is a diagram illustrating a configuration of a conventional semiconductor device for a current control type switching power supply.

FIG. 7 is a block diagram showing a configuration of a control IC shown in FIG.

[Explanation of Symbols] IC, IC1: Control IC, IC2: Phototransistor coupler, Q1: Main switching FET, Q2: Startup FET, Q3, Q4: Transistor, R1 to R24: Resistor, C1 to C19: Capacitor, D1 to D14: Diode, ZD1, ZD2: Zener diode, SCR1: Thyristor, T: Transformer, 100: Rectifier circuit, 101: Reset switch.

Claims (7)

[Claims] 1. A switching power supply for a switching power supply, wherein an IC including a main switching element, a control IC, and peripheral elements of the switching power supply is integrated into two chips or one chip and incorporated in a single package. Semiconductor device. 2. The semiconductor device for a switching power supply,
A start-up circuit, a PWM control circuit, a current limiting circuit, an overvoltage protection circuit, and a protection circuit at the time of a secondary side abnormality;
2. The switching power supply semiconductor device according to claim 1, further comprising a soft start. 3. The magnitude of overvoltage of the overvoltage protection circuit,
3. The switching according to claim 1, wherein the sequence of accepting the secondary side abnormality in the protection circuit at the time of the secondary side abnormality and shutting off the startup is set by a timer circuit in the control IC. Power supply semiconductor device. 4. The switching power supply semiconductor device according to claim 2, wherein a soft start terminal and a secondary side abnormal input terminal are shared. 5. The device according to claim 1, wherein the main switching element is a MOSF.
5. An electronic device according to claim 1, wherein the electronic device is an ET.
4. The semiconductor device for a switching power supply according to any one of the above. 6. The device according to claim 1, wherein said main switching element is a sense switch.
The semiconductor device for a switching power supply according to claim 1, wherein the semiconductor device is an OSFET. 7. The semiconductor device for a switching power supply,
2. The system according to claim 1, further comprising a leading edge blanking (LEB) circuit and a heating protection circuit.
7. The semiconductor device for a switching power supply according to any one of items 1 to 6.