JPH0947091A - Voltage regulator for vehicle charging generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a voltage regulator for vehicle charging generator employing an MOSFET in a switching circuit for turning the rotor coil on/off in which high response to instantaneous output overvoltage or the like is attained while ensuring sufficient reliability for being employed in a vehicle susceptible to EMI. SOLUTION: A switching circuit 4, a switching drive circuit 6 for imparting a driving signal thereto, and a protective circuit 5 for controlling the switching circuit 4 preferentially at the time of abnormality are formed, in multilayer structure, on a single semiconductor chip 9 while sharing an N-type epitaxial layer 412 such that the switching circuit 4 surrounds the switching drive circuit 6 and the protective circuit 5. This structure shortens the interconnection of each circuit significantly to provide high response and high reliability against noise.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage regulator for a vehicle charging generator.

[0002]

2. Description of the Related Art A voltage regulator for a vehicle charging generator controls the power generation of a vehicle charging generator to maintain the charging voltage of a vehicle battery at a predetermined adjustment value.
A switch circuit for performing FF and a voltage adjusting means for applying a drive signal to the switch circuit are provided.

The voltage adjusting means has a set value of the output voltage inside, and the switch circuit is feedback-controlled based on the detected output voltage or the like, or is mounted on the vehicle separately from the charging generator. There is an external voltage control circuit such as a computer provided to control the switch circuit based on an external signal generated from the external voltage control circuit. Some voltage adjusting means configured to provide an external signal from such a separate computer has a protection circuit provided inside thereof for quickly turning off the switch circuit in preference to the external signal.
It is designed to avoid the breakdown of the device caused by the delay of the response of the computer to the overvoltage of the output of the vehicle charging generator due to the sudden decrease of the electric load and the instantaneous or short-term abnormal state such as overheating due to the overload.

The above-mentioned switch circuit, voltage control circuit, and protection circuit provided integrally with the vehicle charging generator have a general structure such as the controller for a vehicle charging generator disclosed in JP-A-60-98833. The switch circuit is composed of bipolar transistors, and the voltage control circuit and the like are integrated into one chip, which are fixed on one hybrid substrate and are connected by a signal line such as an aluminum line through which the drive signal is transmitted.

[0005]

By the way, in recent years, there is a tendency that the electric load mounted on the vehicle increases and the output of the vehicle charging generator increases, and the switch circuit is replaced with the bipolar transistor, and the current driving capability is high. It is expected to be composed of a low-loss double diffusion MOSFET (power MOSFET). The power MOSFET is disclosed in JP-A-58
As disclosed in Japanese Unexamined Patent Publication No. -171861, the effective use of the substrate region has been made to increase the degree of integration of transistor cells to remarkably improve the current driving capability per unit area, and the performance is remarkably improved.

However, while the bipolar transistor which has been conventionally used is a current driving type element, the power MOSFET is a voltage driving type element having a capacitor structure and operates with a minute current, so that the power M
If the switch circuit is configured with the OSFET, the power MOSFET may malfunction due to noise mixed in the signal line reaching the gate of the power MOSFET from the voltage control circuit and the like, and the reliability is sufficient for a vehicle that is susceptible to EMI and the like. I can't say.

Further, as the output of the vehicle charging generator increases, the level of the overvoltage of the output of the vehicle charging generator also increases due to the sudden decrease of the electric load, and the response of the protection circuit cannot be said to be sufficient.
There was a risk that it would not be possible to quickly respond to a momentary abnormal condition.

Therefore, according to the present invention, a MOSF is used in the switch circuit.
In a voltage regulator using an ET, a voltage regulator for a vehicle charging generator that has sufficient reliability even for a vehicle that is susceptible to EMI and the like and has good responsiveness to a momentary abnormal state or the like is provided. To aim.

[0009]

According to the present invention, a power supply to a rotor coil of a vehicle charging generator, which is provided integrally with a vehicle charging generator and is composed of a MOSFET, is turned on / off in response to a drive signal. A switch circuit is provided integrally with the charging generator to detect the output voltage of the vehicle charging generator and apply a drive signal to the switching circuit to maintain a predetermined set value to turn the switching circuit on and off. in the voltage regulator of a vehicle charging generator comprising a voltage control circuit for feedback controlling by switching the bets, the switch circuit N ^- P in the surface layer portion of the type epitaxial layer
-Type, N ⁺ -type diffusion layer is diffused twice or more to form an N-channel D-MOSFET in which the N ⁺ -type diffusion layer serves as an N-type channel, and the voltage control circuit is provided on the surface layer portion of the N ⁻ -type epitaxial layer. On a lateral MOSFET in which a P type diffusion layer is formed and a pair of N ⁺ type diffusion layers are formed in the P type diffusion layer to form a source portion and a drain portion, and on an oxide film formed on the N ⁻ type epitaxial layer. And the P ⁺ -type diffusion layer and the N ⁺ -type diffusion layer which are partially in contact with the surface layer portion of the P-type diffusion layer, the P ⁺ -type diffusion layer serving as an anode, and the N ⁺ -type diffusion layer. The diode is used as a layer and the switch circuit and the voltage control circuit are formed on a single semiconductor chip.

The switch circuit and the voltage control circuit include the N-channel D-MOSFET and the lateral MOS.
A planar structure in which an FET or the like shares the N ⁻ type epitaxial layer in common, the N ⁻ type epitaxial layer, the oxide film,
By having a laminated structure formed of the above resistance, it is formed with a high degree of integration on a single semiconductor chip. However, the wiring length inside the semiconductor chip is remarkably shortened, the mixing of noise is reduced, the signal transmission speed from the voltage control circuit to the switch circuit is accelerated, and the output voltage is well responsive. Is fed back to the operation of.

Further, a switch circuit which is provided integrally with the vehicle charging generator and is composed of a MOSFET and turns ON / OFF the power supply to the rotor coil of the vehicle charging generator in response to a drive signal, and the vehicle charging power generation. An external voltage control circuit that is provided separately from the machine and that issues an external signal to adjust the output voltage of the vehicle charging generator, and an external input terminal that is provided integrally with the vehicle charging generator and that receives the external signal,
A switching drive circuit provided integrally with the vehicle charging generator in response to an external signal input through the external input terminal to generate the drive signal and output the drive signal to the switch circuit; In a voltage regulator for a vehicle charging generator, which is provided integrally with a vehicle charging generator, and which includes a protection circuit for controlling the switching circuit prior to the switching drive circuit in the event of an abnormality, the switching circuit is an N ^- type epitaxial layer. P type on the surface layer of
The N ⁺ type diffusion layer is diffused twice or more, and the N ⁺ type diffusion layer is N
The switching drive circuit and the protection circuit form a P-type diffusion layer on the surface layer portion of the N ^- type epitaxial layer and a pair of N ^{+ on the} P-type diffusion layer. A lateral MOSFET having a source diffusion region formed by forming a diffusion layer
And a resistor formed on the oxide film formed on the N ⁻ type epitaxial layer, and a P ⁺ type diffusion layer and an N ⁺ type diffusion layer partially contacting the surface layer portion of the P type diffusion layer. Above P ⁺
The diode is used with the type diffusion layer as an anode and the N ⁺ type diffusion layer as a cathode, and the switch circuit, the switching drive circuit and the protection circuit are formed on a single semiconductor chip.

The switch circuit, the switching drive circuit, and the protection circuit are the N-channel D-MOSFE.
On the single semiconductor chip, T, the lateral MOSFET and the like have a planar structure in which the N ⁻ type epitaxial layer is common and a laminated structure formed by the N ⁻ type epitaxial layer, the oxide film and the resistor. It is formed with a high degree of integration. Therefore, the wiring length inside the semiconductor chip is remarkably shortened, the mixing of noise is reduced, the signal transmission speed from the switching drive circuit to the switch circuit is accelerated, and the output voltage is responsive with good response. The protection circuit operates with good responsiveness to an instantaneous abnormal state of the output voltage.

Therefore, the voltage adjusting device for a vehicle charging generator according to the present invention has sufficient reliability for a vehicle which is susceptible to EMI and the like, and also has good responsiveness to momentary abnormal states and the like. .

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a voltage regulator as an embodiment to which the present invention is applied. In the figure, a power generation section 2 of a vehicle charging generator (hereinafter referred to as a charging generator) 1 includes a rotor coil 21 and a stator coil 22, and a generated voltage generated in the stator coil 22 passes through a full-wave rectifier 3 and a charging line 11. It is supplied to the vehicle-mounted battery 8. In the charging generator 1, a switch circuit 4, a voltage control circuit 5, and a switching drive circuit 6 are formed integrally with the charging generator 1 on a single semiconductor chip 9 whose structure will be described later. Further, an external voltage control circuit 7 is provided separately from the charging generator 1, and these constitute a voltage adjusting device.

The switch circuit 4 comprises a power transistor 41 for turning on and off the exciting current of the rotor coil 21, and a flywheel diode 42 connected in series to the power transistor 41. The power transistor 41 is an N-channel vertical D type. -A MOSFET.

The voltage control circuit 5 is an N-channel lateral type D-M.
Transistors 51, 52, 53 of OSFET, resistor 54
a, 54b, 54c, 54d, 54e, 54f, 54g
And a zener diode 55, and a charging generator 1
And the drain of the transistor 51 is connected to the gate of the power transistor 41. The transistor 51 is kept in the OFF state while the fed back output voltage does not exceed the set value determined by the Zener voltage. In this embodiment, the resistors 54b, 54d to 54g and the transistor 5 are used.
2 constitutes a hysteresis circuit, whereby the first set value has hysteresis between 13V and 16V, for example.

The switching drive circuit 6 comprises an N-channel lateral D-MOSFET transistor 61 and a Zener diode 63. An external signal 7a is input to the gate of the transistor 61 and its drain is connected to the gate of the transistor 41. .

The external signal 7a is input from an external voltage control circuit 7 separate from the charging generator 1 via a terminal 12 provided in the charging generator 1. The external voltage control circuit 7 is, for example, a vehicle-mounted control computer, and the battery charging voltage is fed back via the key switch 81. The external voltage control circuit 7 inputs various signals indicating a running state of the vehicle, a charging state of the battery 8, an electric load state, etc., and sets the battery to the second set value optimally set according to these signals. The external signal 7a is output in order to follow the charging voltage. Here, the second set value is 15V
It is set below. When the battery charging voltage is lower than the second set value, the external signal 7a is set to "0" level, and the transistor 61 is turned off. At this time, since the output voltage of the charging generator 1 is lower than the first set value, the transistor 51 is in the OFF state, and as a result, the power transistor 41 is turned on, the rotor coil current flows, and power generation starts. To be done.

When the battery charging voltage becomes higher than the second set value and when the key switch 81 is not turned on, the external signal 7a is set to "1" level. As a result, the transistor 61 is turned on,
The power transistor 41 is forcibly turned off. Since the external signal 7a is a high and low binary signal of "1" and "0", the transistor 6 is not affected even if some noise is mixed.
1 turns on and off in response to the external signal 7a.

FIG. 2 shows a schematic plan view of a semiconductor chip 9 on which the switch circuit 4, the voltage control circuit 5 and the switching drive circuit 6 are formed. On a rectangular semiconductor chip 9, a power transistor 41 is formed in a U-shaped region A that occupies most of it, as will be described later, and transistors 51 to 51 are formed in a region B located between the regions A at a substantially central position. 5
3, 61, resistors 54a to 54g, Zener diode 5
5, 63 are formed so that the sources of the transistors 51, 61 formed in the region B are connected to the gate of the power transistor 41 formed in the region A surrounding them in the shortest distance. The diode 42 is formed in the region C, and the terminal 12 is provided in the region E.

FIG. 3 is a sectional view taken along line III-III of FIG. An N ⁻ -type silicon epitaxial layer 412 is formed on the N ⁺ -type silicon substrate 411 which has an electrode formed on the back surface to serve as the drain 420. A P type diffusion layer 414 is formed and an N ⁺ type diffusion layer 415 is further formed. An oxide film 4 is formed on the epitaxial layer 412.
A gate 417 made of a polycrystalline silicon layer is formed via the insulating film 16 and an insulating film 418 covering the gate 417 is further covered to form an aluminum electrode to serve as a source 419. Thus, the vertical D-MOSFET is constructed.

That is, when a voltage is applied to the gate 417, an N-type channel appears on the surface portion of the diffusion layer 414 indicated by Ch in the figure, and the drain 420 below the source 419 above.
An electric current flows toward. The vertical type D-
A large number of MOSFETs are formed to form a power transistor 41 having a large current capacity and a small loss.

The diffusion layer 4 is formed by overlapping a part thereof.
Reference numerals 13 and 414 are overvoltage protection layers having a predetermined breakdown voltage.

In the region B, a P type diffusion layer 511 is formed in the epitaxial layer 412, and a pair of N ⁺ type diffusion layers 512 are formed in the diffusion layer 511 to form a source portion and a drain portion. The source 513, the gate 514, and the drain 515 on the upper surface of 511 form a lateral D-MOSFET transistor 51. Part of the diffusion layer 511 is in contact with the P ⁺ type diffusion layer 631 and the N ⁺ type diffusion layer 6
A zener diode 63 having a P ⁺ -type diffusion layer 631 as an anode and an N ⁺ -type diffusion layer 632 as a cathode.
There is. The diode 42 is also made of a diffusion layer.

An oxide film 551 is formed on the diffusion layer 511.
And a PN junction layer 552 of polycrystalline silicon is formed on the oxide film 551 to form a Zener diode 55. The resistor 54 is formed by forming a polycrystalline silicon layer 553 on the oxide film 551. Therefore, unlike a resistor formed by impurity diffusion, there is no parasitic transistor, malfunctions due to power supply noise and the like are prevented, trimming is possible, and a high-quality semiconductor chip is obtained.

As described above, the vertical D-MOS is provided in the regions A and B.
FET, lateral D-MOSFET, Zener diode 6
Together formed the type of silicon epitaxial layer 412 as a common part, N ^{- -} 3 etc. N -type silicon epitaxial layer 412 can increase the integration degree by the oxide film 551, the resistor 54 is a laminated structure.

In the voltage regulator having the above structure, the ON / OFF operation of the power transistor 41 is normally controlled by the external signal 7a output from the external voltage control circuit 7. As a result, the battery charging voltage is determined by the running condition of the vehicle. Is adjusted to the second set value as the optimum adjusted value. As a result, for example, it is possible to suppress power generation during idling when the electric load is low, enable idle rotation to be lower, and improve fuel consumption.

In this state, for example, when the output portion of the external voltage control circuit 7 fails and the external signal 7a has an accident of "0" level, the transistor 61 is turned off, and thereafter the power transistor 41 is turned on. -OFF operation is controlled by the voltage control circuit 5 as a protection circuit,
The output voltage of the charging generator 1 is maintained at the first set value.
In addition, when an external signal 7a has an accident of "1" level due to a failure of the output portion of the external voltage control circuit 7 or an external signal 7a is disconnected at the terminal 12, an accident occurs. Is turned on, the power transistor 41 is turned off, and the power generation of the charging generator 1 is stopped. Thus, the power generation of the charging generator 1 does not become uncontrolled, and the accident of overcharging does not occur.

In the normal control of the external voltage control circuit 7, when the external signal 7a is at "0" level and the output of the charging generator 1 momentarily causes an overvoltage due to the sudden decrease of the electric load, it functions as a protection circuit. The voltage control circuit 5 turns off the switch circuit 4.

The semiconductor chip 9 has a device structure in which the wiring length is remarkably shortened as described above, and the wiring length from the voltage control circuit 5 and the switching drive circuit 6 to the gate of the power transistor 41 is short. The switch circuit 4, the voltage control circuit 5, the switching drive circuit 6 and the like are laid out so that As a result, the drive signal is transmitted from the switching drive circuit 6 to the switch circuit 4 composed of MOSFETs without being affected by noise. Further, the switch circuit 4 is turned on and off with good response by the drive signal from the switching drive circuit 6 and the voltage control circuit 5, and the output voltage is controlled with high accuracy.
Further, the voltage control circuit 5 as a protection circuit has good responsiveness when the switch circuit 4 is turned off against an instantaneous overvoltage of the charging generator 1, and the charging generator 1 fails even if an instantaneous overvoltage occurs. Is reliably prevented.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a voltage adjusting device for a vehicle charging generator to which the present invention is applied.

FIG. 2 is a schematic plan view of a semiconductor chip forming each circuit of a voltage adjusting device for a vehicle charging generator to which the present invention is applied.

FIG. 3 is a sectional view taken along line III-III of FIG. 2;

[Explanation of symbols]

1 Vehicle Charging Generator 22 Rotor Coil 4 Switching Circuit 41 Power Transistor (N Channel D-MOSFE
T) 411 N ⁺ type silicon substrate 412 Silicon epitaxial layer (N ⁻ type epitaxial layer) 413, 414 P type diffusion layer 415, 512, 632 N ⁺ type diffusion layer 5 Voltage control circuit, protection circuit 51 N channel lateral D-MOSFET (Horizontal MOSF
ET) 511 P-type diffusion layer 6 Switching drive circuit 61 Switching element 631 P ⁺ type diffusion layer 7 External voltage control circuit 8 In-vehicle battery 12 Terminal (external input terminal)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazumasa Mori 1-1-1, Showa-cho, Kariya city, Aichi prefecture Nihon Denso Co., Ltd.

Claims (6)

[Claims] 1. A vehicle charging generator integrally provided with M
A switch circuit configured by an OSFET for turning on / off power supply to the rotor coil of the vehicle charging generator in response to a drive signal, and an output voltage of the vehicle charging generator provided integrally with the vehicle charging generator. A voltage control device for a vehicle charging generator, which comprises a voltage control circuit for detecting and maintaining a predetermined set value by applying a drive signal to the switch circuit to switch the switch circuit between an ON state and an OFF state for feedback control. , The switch circuit is N ⁻
2 P-type and N ⁺ -type diffusion layers on the surface of the epitaxial layer
An N-channel D-MOSFET in which the N ⁺ -type diffusion layer is diffused more than once to form an N-type channel, and the voltage control circuit forms a P-type diffusion layer on the surface layer of the N ⁻ -type epitaxial layer and A lateral MOSF in which a pair of N ⁺ type diffusion layers are formed in a P type diffusion layer to form a source portion and a drain portion.
ET, the resistance formed on the oxide film formed on the N ⁻ type epitaxial layer, and the P ⁺ type diffusion layer and the N ⁺ type diffusion layer which are partially in contact with the surface layer portion of the P type diffusion layer are formed. And a diode having the P ⁺ -type diffusion layer as an anode and the N ⁺ -type diffusion layer as a cathode, and the switch circuit and the voltage control circuit are formed on a single semiconductor chip. Voltage regulator for vehicle charging generator. 2. The voltage regulator for a vehicle charging generator according to claim 1, wherein the resistor is made of a polycrystalline semiconductor formed on the oxide film. 3. The vehicle charging according to claim 1 or 2, wherein the voltage control circuit is formed in a substantially central region of the semiconductor chip, and the switch circuit is formed around the voltage control circuit. Generator voltage regulator. 4. A vehicle charging generator integrally provided with M
A switch circuit configured by an OSFET for turning on / off power supply to the rotor coil of the vehicle charging generator in response to a drive signal, and an output voltage of the vehicle charging generator provided separately from the vehicle charging generator. An external voltage control circuit that issues an external signal to adjust the external voltage, an external input terminal that is provided integrally with the vehicle charging generator and that receives the external signal, and an external input terminal that is provided integrally with the vehicle charging generator. A switching drive circuit that operates in response to an external signal input via the switching drive circuit to generate the drive signal and output the drive signal to the switch circuit, and the switching drive circuit provided integrally with the vehicle charging generator when an abnormality occurs in the voltage regulator of a vehicle charging generator with priority; and a protection circuit for controlling the switch circuit, the switch circuit N ^- type d P-type in a surface portion of the Takisharu layer, N ⁺
An N-channel D-MOSFET in which the N ⁺ -type diffusion layer serves as an N-type channel by diffusing the type diffusion layer two or more times, and the switching drive circuit and the protection circuit include the N-type D-MOSFET.
^- source portion to form a pair of N ⁺ -type diffusion layer on the P-type diffusion layer to form a P-type diffusion layer in the surface layer portion of the type epitaxial layer, and a lateral MOSFET having no drain portion, the N ^- type epitaxial The resistance formed on the oxide film formed on the layer and the P ⁺ type diffusion layer and the N ⁺ type diffusion layer which are partially in contact with the surface layer portion of the P type diffusion layer are formed to form the P ⁺ type diffusion layer. A vehicle charging generator comprising an anode and a diode having the N ⁺ -type diffusion layer as a cathode, and forming the switch circuit, the switching drive circuit and the protection circuit on a single semiconductor chip. Voltage regulator. 5. The voltage regulator for a vehicle charging generator according to claim 4, wherein the resistor is a polycrystalline semiconductor formed on the oxide film. 6. The switching drive circuit and the protection circuit are formed in a substantially central region of the semiconductor chip, and the switch circuit is formed around the switching drive circuit and the protection circuit. Alternatively, the voltage adjusting device for the vehicle charging generator according to the fifth aspect.