JP4285798B2 - Semiconductor device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor device used in a magnetic recording device such as a floppy disk drive device.
[0002]
[Prior art]
A conventional magnetic recording apparatus will be described. FIG. 5 is a diagram showing the arrangement of each circuit in an LSI (Large Scale Integrated Circuit) 60 used in a floppy disk drive apparatus which is a kind of conventional magnetic recording apparatus. The LSI 60 includes a large current driver circuit 20, an analog signal processing circuit 21, a controller 22, and a thermal shutdown circuit 23.
[0003]
The large current driver circuit 20 supplies current to a stepping motor (not shown) by an on / off operation to drive the stepping motor. The stepping motor is a motor that moves a read / write head (not shown) to a predetermined track position.
[0004]
The analog signal processing circuit 21 processes an analog signal when data is written to or read from a floppy disk that is a magnetic recording medium. The controller 22 interfaces with a personal computer (not shown) as a host and controls the large current driver circuit 20 and the analog signal processing circuit 21.
[0005]
The thermal shutdown circuit 23 has a temperature detection circuit inside, and the temperature detection circuit detects the temperature of the LSI 60. Although heat is generated by the operation of the large current driver circuit 20, the thermal shutdown circuit 23 forcibly turns off the large current driver circuit 20 when abnormal heat generation occurs at a temperature exceeding a certain reference value. Since the large current driver circuit 20 generates heat upon operation, the thermal shutdown circuit 23 prevents the LSI 60 from malfunctioning due to a high temperature due to abnormal heat generation. Here, the temperature detection circuit is a circuit shown in FIG. 3 as described later in detail.
[0006]
[Problems to be solved by the invention]
However, conventionally, since the large current driver circuit 20 and the thermal shutdown circuit 23 are provided close to each other as shown in FIG. 5, when the on / off operation of the large current driver circuit 20 is switched as shown in FIG. A back electromotive force is generated by a coil in a connected stepping motor (not shown), and a current due to the back electromotive force flows to the ground side of the large current driver circuit 20 through the IC substrate, and current is drawn from the ground side. Therefore, noise of about 0.1 V is generated in the ground level VG around the large current driver circuit 20.
[0007]
For example, when the operation of the large current driver circuit 20 is switched from on to off at time t1, noise 70 is generated in the ground level VG. At this time, the margin voltage up to the detection voltage VT changes from the arrow 71 to the arrow 72 due to the noise 70. As described above, noise is generated when the on / off operation of the large current driver circuit 20 is switched, and the detection voltage changes. Therefore, the temperature detected by the temperature detection circuit changes. Therefore, highly accurate temperature detection cannot be performed, and the noise may affect the temperature detection in the thermal shutdown circuit 23.
[0008]
The present invention is intended to solve the above problems, and an object thereof is to provide a semiconductor device such as an LSI capable of temperature detection stabilized by the temperature detection circuit having a thermal shutdown circuit. Furthermore, also an object to reduce the chip area by devising the placement Te semiconductor device smell.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, in the semiconductor device of the present invention, a large current driver circuit that generates noise and heat in accordance with current output and a temperature due to heat generation of the large current driver circuit that is also a noise generation source are detected. A temperature detection circuit; a signal processing circuit arranged between the large current driver circuit and the temperature detection circuit for processing an analog signal for writing or reading data to a magnetic recording medium; the large current driver circuit; and the signal and a controller for controlling the processing circuit, the temperature detection circuit is the so that with GND wiring is not common with the large current driver circuit.
[0010]
According to such a configuration, the temperature detection circuit included in the thermal shutdown circuit or the like in the semiconductor device is located away from the large current driver circuit across the signal processing circuit, and the GND wiring (analog circuit that is not common to the large current driver) because of the use of shared) and the temperature detection circuit ceases to little effect on the ground level or the like even when a large current driver circuit operates for example on / off. In the magnetic recording apparatus, for example, a stepping motor is driven by a large current driver circuit. At this time, when the high-current driver circuit is operating, signal reading and writing are not performed, so that the signal processing circuit is in an inoperative state. Therefore, even if the signal processing circuit is adjacent to the large current driver circuit, it is not affected by noise generated by the operation of the large current driver circuit.
[0011]
In the present invention, in the above configuration, the large current driver circuit is further controlled based on the detection result of the temperature detection circuit .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described. FIG. 1 is a block diagram of a floppy (registered trademark) disk drive device to which a semiconductor device of the present invention is applied. The LSI 1 transmits and receives data with a personal computer (hereinafter referred to as “personal computer host”) 2 that is a host of a floppy (registered trademark) disk drive device and an interface driver 10, and the controller 12 controls the LSI 1. The analog signal processing circuit 13 processes an analog signal for writing or reading data on a floppy (registered trademark) disk (not shown).
[0013]
The LSI 1 includes an interface driver 10 that transmits and receives data to and from the personal computer host 2, a stepping motor driver 11 that drives the stepping motor 3, an analog signal processing circuit 13, and a controller 12 that controls these.
[0014]
The index sensor 5 reacts when the disk rotates once. Therefore, the controller 12 can determine whether or not there is a disk. The spindle motor 7 is driven by a spindle motor driver 6, and the spindle motor driver 6 is controlled by a controller 12.
[0015]
The analog signal processing circuit 13 writes / reads data to / from the floppy disk by the read / write head 9. Further, the erase head 8 erases a remaining portion of unnecessary data on the floppy disk caused by a slight positional deviation of the track position of the read / write head 9 during the write operation of the read / write head 9.
[0016]
The track sensor 4 is used to determine the track position of the erase head 8 by mechanically reacting at the position of the track number 0 to determine the track position of the erase head 8.
[0017]
FIG. 2 is a diagram showing the arrangement of each circuit in the LSI 1. The large current driver circuit 20 is a current output unit of the stepping motor driver 11 in FIG. The large current driver circuit 20 is in contact with one side of the LSI 1. A controller 12 is provided adjacent to the large current driver circuit 20 . An analog signal processing circuit 13 is provided adjacent to the large current driver circuit 20 and the controller 12 .
[0018]
A thermal shutdown circuit 23 is provided at a corner that is opposite to the large current driver circuit 20. Therefore, the analog signal processing circuit 13 is disposed between the thermal shutdown circuit 23 and the large current driver circuit 20. The thermal shutdown circuit 23 has the temperature detection circuit shown in FIG. 3, and when the LSI 1 exceeds a certain reference value according to the detection result, the large current driver circuit 20 is turned off.
[0019]
As shown in FIG. 2, an analog signal processing circuit 13 is disposed between the large current driver circuit 20 and the thermal shutdown circuit 23, and a certain distance is provided because the GND line is not shared. . Therefore, noise generated by the on / off operation of the large current driver circuit 20 hardly affects the thermal shutdown circuit 23. In addition, when the large current driver circuit 20 is turned on / off, the analog signal processing circuit 13 is not operated, so that the accuracy of the thermal shutdown circuit 23 is not significantly lowered.
[0020]
A temperature detection circuit in the thermal shutdown circuit 23 is shown in FIG. The constant current source circuit 30 outputs a constant current I to point A. The constant current I flows from the point A through the resistor 32 to the ground level, and the voltage VT at the point A is kept at about 0.5 V at room temperature. The point A is connected to the base of the NPN transistor 34. The emitter of the transistor 34 is grounded. The collector of the transistor 34 is connected to the power supply voltage via the resistor 33, and a signal OUT indicating the temperature detection result is output from the collector.
[0021]
The resistor 32 and the like have some temperature characteristics, but the point A is kept almost constant even if the temperature of the LSI 1 rises. The NPN transistor 34 is a switching transistor, and the threshold voltage VF between the base and the emitter that is switched on / off is about 0.7 V at room temperature. When a voltage higher than the threshold voltage VF is applied between the base and the emitter, the NPN transistor 34 is turned on.
[0022]
At room temperature, the voltage VT at point A is maintained at about 0.5 V, so the NPN transistor 34 is off. For this reason, the signal OUT is at a high level. When the temperature of the LSI 1 rises, the threshold voltage VF falls, and when it finally falls below the voltage VT at the point A, the transistor 34 is turned on and the signal OUT becomes a low level.
[0023]
In this way, the temperature detection circuit detects the temperature of the LSI 1. Therefore, the signal OUT is at a high level at room temperature, but the signal OUT is set to a low level when the temperature becomes higher than 150 ° C., for example. The thermal shutdown circuit 23 (see FIG. 2) turns off the large current driver circuit 20 (see FIG. 2) when the signal OUT of the temperature detection circuit becomes low level.
[0024]
As shown in FIG. 4, even if the large current driver circuit 20 (see FIG. 2) is operated so as to be switched on / off, almost no noise is generated in both the voltage VT and the ground level VG of the thermal shutdown circuit 23. Absent. Therefore, even when the large current driver circuit 20 is switched on / off, the detection voltage is kept stable as indicated by the arrow 40, so that the influence of noise due to the counter electromotive force does not occur in the temperature detection. Yes.
[0025]
As described above, in this embodiment, in the LSI 1 used in the floppy (registered trademark) disk drive device or the like, the analog signal processing circuit 13 is interposed between the large current driver circuit 20 and the thermal shutdown circuit 23, and a certain amount Since the distance is provided, the on / off operation of the large current driver circuit 20 hardly affects the temperature detection in the thermal shutdown circuit 23. Furthermore, since the thermal shutdown circuit 23 is provided at the corner portion of the LSI 1, the surface of the LSI 1 can be used effectively, and the chip area can be reduced.
[0026]
【The invention's effect】
As described above, according to the semiconductor device of the present invention, since a position temperature detecting circuit has left the high-current driver circuit across the signal processing circuit, the temperature by on / off operation of the high-current driver circuit no significant effect on the detection circuitry, which enables highly accurate and stable temperature detection.
[Brief description of the drawings]
FIG. 1 is a block diagram of a floppy disk drive apparatus according to an embodiment of the present invention.
FIG. 2 is a view showing an arrangement of circuits in an LSI of the floppy disk drive device.
FIG. 3 is a circuit diagram of a temperature detection circuit in the LSI.
FIG. 4 is a waveform diagram showing the operation of the LSI.
FIG. 5 is a diagram showing an arrangement of circuits in an LSI of a conventional floppy disk drive device.
FIG. 6 is a waveform diagram showing the operation of the LSI.
[Explanation of symbols]
1 LSI
2 PC host 3 Stepping motor 4 Track sensor 5 Index sensor 6 Spindle motor driver 7 Spindle motor 8 Erase head 9 Read / write head 10 Interface driver 11 Stepping motor driver 12 Controller 13 Analog signal processing circuit

Claims (2)

A high-current driver circuit that generates noise and heat with the output of current;
A temperature detection circuit for detecting a temperature due to heat generation of the large current driver circuit which is also a noise generation source;
A signal processing circuit that is arranged between the high-current driver circuit and the temperature detection circuit and processes an analog signal for writing or reading data on a magnetic recording medium;
A controller for controlling the large current driver circuit and the signal processing circuit ,
A semiconductor device characterized in that the temperature detection circuit uses a GND wiring that is not common to the high-current driver circuit .   The semiconductor device according to claim 1, wherein the high-current driver circuit is controlled based on a detection result of the temperature detection circuit.

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