JP2522054B2 - Semiconductor device - Google Patents

Description

The present invention relates to a semiconductor device, and more particularly to a semiconductor device used in a semiconductor integrated circuit for a motor drive having an H bridge circuit composed of four N-type field effect transistors at an output stage. Booster circuit.

[Conventional technology]

Conventionally, this type of circuit includes a booster circuit that combines a diode, a capacitor, and an oscillator circuit. That is, the third
As shown in the figure, the output of the oscillation circuit 10 driven by the power supply 9 is connected to the gate of the N-channel transistor of the output circuit 12 through the inverter 3 and the diodes 7, 8 and 18 in series, and the capacitor 6 is connected. Ground via inverter 3
The capacitor 4 is connected between the input side of and the connection point between the diodes 7 and 8, and the capacitor 5 is connected between the output side of the inverter 3 and the connection point between the diodes 8 and 18, The boosted voltage was obtained at the connection point between the capacitor 6 and the capacitor 6. This boosted voltage drives, for example, an output H bridge circuit composed of four N-type field effect transistors.

[Problems to be Solved by the Invention]

The above-mentioned conventional booster circuit is the power supply voltage of the oscillator circuit.
The output H bridge circuit was driven by boosting to 3 times V _C. This is because it is necessary to boost the power source voltage V _M (V _C ) of the output circuit in order to reduce the on-resistance of the N-type field effect transistor. Specifically, when V _C is 5V, the boost voltage is 13V, taking into account 3 V _F voltage drops of the diode.
When V _M is about 5V, it gets enough voltage to drive the output circuit. But if V _M is higher than V _C , for example V _C
When V _M is 5 V and V _M is 12 V, the boosted voltage from V _M becomes about 1 to 2 V, which has a drawback that the on-resistance increases.

[Means for solving the problem]

A booster circuit of the present invention includes a first power supply terminal, an oscillation circuit connected to the first power supply terminal, an inverter receiving the output of the oscillation circuit, and a first output receiving the inverter.
Connection circuit of the first capacitor and the first and second diodes, the output terminal and the second capacitor connected to the output of the series connection circuit, the input side of the inverter and the first and second diodes A third capacitor connected between the points, a third diode connected between the connection point of the first capacitor and the first diode and the first power supply terminal, and a first power supply terminal And a fourth diode connected between the connection point of the first and second diodes, and a second power supply line different from the first power supply line, a first capacitor and a first diode. And a sixth diode connected between the second power supply terminal and the connection point of the first and second diodes. . That is, in the booster circuit of the present invention, the one which is not directly connected to the power supply and the capacitor in the past is connected by using the diode, and when the control power supply _C is higher than the power supply V _{M of the} output circuit, V _C becomes 3 × V _C. When it is lower than V _M, it becomes V _M + 2 × V _C. As a result, the output circuit can always be driven at a voltage higher than V _M by about 8 V regardless of the motor voltage V _M , so that a low on-resistance can be achieved regardless of V _M. Further, when the present invention is used, the decrease in the boosted voltage due to the diode V _F can be made the same as that in the conventional circuit, so that it has the characteristic that the characteristic deterioration due to the addition of the function does not occur.

Zener diodes can be used as the third, fourth, fifth, and sixth diodes.

As described above, the conventional booster circuit could boost up to three times the control power supply of the oscillation circuit, but in the present invention, a diode is added to further control the power supply voltage of the output circuit as a reference. It is possible to boost up to twice the power supply. This makes it possible to realize a sufficiently low on-resistance regardless of what voltage is used for the power supply of the output circuit.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram of a booster circuit showing an embodiment of the present invention. The oscillation circuit 10 is driven by the power supply line 9. The output of the oscillator circuit 10 is connected to the output circuit via a series circuit of an inverter 3, a capacitor 4, a diode 7, and a diode 8. The capacitor 5 is connected between the input end of the inverter 3 and the connection point between the diodes 7 and 8.
Both ends of the diode 7 are zener diode 1 and
It is connected to the power supply line 9 via 2. In addition, both ends of this are further connected to the power line 11 via the Zener diodes 3 and 4.
Is also connected to. Therefore, both ends of the diode 7 become the higher voltage of the power supply lines 9 and 11, so that it is possible to further boost up to twice the power supply voltage based on this voltage.

FIG. 2 is a circuit of another embodiment of the present invention. The basic operation is the same as that of the first embodiment, and in particular, in order to protect the power supply when the capacitor 6 is short-circuited and broken, resistances are respectively provided between the Zener diodes 1, 2 and 3, 4 and the power supply lines 9 and 11.
Contains 16,17 and 18,19. In this way, the effect of the first embodiment remains unchanged, and a booster circuit having a power supply protection function can be constructed.

〔The invention's effect〕

As described above, according to the present invention, a diode is newly used in the booster circuit so that only the control power supply of the oscillator circuit is required, and the power supply of the output circuit and the booster circuit are connected to each other.
As shown in FIG. 4, the boosted voltage can be further boosted up to twice the control power supply V _{C based on} the power supply V _{M of the} output circuit.

As a result, when an H bridge circuit composed of four N-type field effect transistors is used in the output circuit, as shown in FIG. 5, in the conventional circuit, when the power supply voltage of the output circuit becomes high, the on resistance of the output circuit sharply increases. Although it is higher, the circuit of the present invention can have a substantially constant on resistance regardless of the power supply voltage of the output circuit.

[Brief description of drawings]

1 and 2 are circuit diagrams of a booster circuit according to one embodiment and another embodiment of the present invention, respectively, and FIG. 3 is a circuit diagram of a booster circuit of the related art. FIG. 4 is a diagram showing the relationship between the boosting time and the boosted voltage, and FIG. 5 is a diagram showing the relationship between the power supply voltage of the output circuit and the on-resistance of the output circuit. 1 ... (Zener) diode, 2 ... (Zener) diode, 3 ... Inverter, 4 ... Capacitor, 5
...... Capacitor, 6 ...... Capacitor, 7 ...... Diode, 8 ...... Diode, 9 ...... Power line, 10 ...... Oscillation circuit, 11 ...... Power line, 12 ...... Output circuit, 13 ......
(Zener) diode, 14 …… (Zener) diode, 15 …… resistor, 16 …… resistor, 17 …… resistor, 18 …… resistor.

Claims (3)

(57) [Claims] 1. A first power supply terminal, an oscillating circuit connected to the first power supply terminal, an inverter for receiving the output of the oscillating circuit, a first capacitor for receiving the output of the inverter, and a first and a second capacitor. A series connection circuit with a second diode, an output terminal connected to an output of the series connection circuit, a second capacitor, an input side of the inverter, and the first
And a third capacitor connected between a connection point of the second diode and a third capacitor connected between a connection point of the first capacitor and the first diode and a first power supply terminal. Second power supply different from the first power supply line, and a fourth diode connected between the first power supply terminal and the connection point of the first and second diodes. A line, a fifth diode connected between the connection point of the first capacitor and the first diode, the second power supply terminal, and a connection point of the first and second diodes. A semiconductor device including a sixth diode connected between them 2. The third and fourth diodes and the first diode
2. The semiconductor device according to claim 1, further comprising: a protection resistor connected to the power supply terminal of the second power supply and between the fifth and sixth diodes and the second power supply. 3. The semiconductor device according to claim 1, wherein the third, fourth, fifth and sixth diodes are Zener diodes.