Static information storage and retrieval – Powering
Reexamination Certificate
2001-05-21
2003-05-06
Le, Vu A. (Department: 2824)
Static information storage and retrieval
Powering
C365S227000
Reexamination Certificate
active
06560157
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device in which a voltage dropping circuit is arranged to drop a voltage of electric power supplied from a voltage source and to output a dropped voltage, and more particularly to a semiconductor device which can be easily connected and operated with each of various types of integrated circuits for power supply.
2. Description of Related Art
FIG. 8
is a block diagram showing the configuration of a conventional power supply system. In
FIG. 8
, referential numeral
101
indicates a chip of conventional semiconductor device for receiving a voltage from a voltage supply source and performing an operation by using electric power of the voltage.
102
indicates a power supply integrated circuit (hereinafter, called a power supply IC) for supplying current of a high voltage to the semiconductor device
101
.
103
indicates a power supply terminal which is arranged in the semiconductor device
101
and is connected with a wire which extends from the power supply IC
102
.
104
indicates an internal circuit.
105
indicates a main voltage dropping circuit for dropping the high voltage applied to the power supply terminal
103
to a prescribed voltage required to operate the internal circuit
104
.
106
indicates a secondary voltage dropping circuit which has the same function as that of the main voltage dropping circuit
105
. A current supplying capability and an electric power consumption rate in the secondary voltage dropping circuit
106
are smaller than those in the main voltage dropping circuit
105
.
Next, an operation of the conventional power supply system will be described below.
Developments in advanced manufacturing of transistors in large scaled integrated (LSI) circuits have lead to reductions in the operation voltage of each transistor. Therefore this has resulted in difficulties with respect to applying conventional transistors which are operated at a standard operation voltage of 5V. Nowadays, integrated circuits (ICs) such as semiconductor devices are manufactured in consideration of the above-described restriction on the ICs. That is, even though it is required to apply a voltage of 5V to an input/output section of the semiconductor device
101
, it is required to operate the internal circuit
104
of the semiconductor device
101
at a low voltage. Therefore, in cases where it is required to apply a voltage of 5V to an input/output section of the semiconductor device
101
, one of two methods is adopted to operate the internal circuit
104
of the semiconductor device
101
at a low voltage. In the first method, as shown in
FIG. 8
, dropping circuits represented by the main voltage dropping circuit
105
and the secondary voltage dropping circuit
106
are arranged in the semiconductor device
101
. In this case, the power supply IC
102
of one-voltage supply type can be used for the semiconductor device
101
, and a manufacturing cost of the conventional power supply system can be reduced.
In general, in cases where a dropping circuit is arranged in the semiconductor device
101
according to the first method, though a manufacturing cost of the conventional power supply system can be reduced, electric power consumed in the dropping circuit is heightened. For example, in cases where an operation frequency in the internal circuit
104
is reduced to reduce electric power consumed in the internal circuit
104
, parts of the internal circuit
104
are operated, and the electric power supply for the other parts of the internal circuit
104
is stopped by disconnecting the other parts of the internal circuit
104
from a power supply IC. In this case, electric power consumed in the dropping circuit is larger than that consumed in the internal circuit
104
. Therefore, as shown in
FIG. 8
, the main voltage dropping circuit
105
and the secondary voltage dropping circuit
106
are arranged in the semiconductor device
101
. The main voltage dropping circuit
105
is characterized by a high response speed for voltage change, a large current supplying capability and a large electric power consumption rate. The secondary voltage dropping circuit
106
is characterized by a low response speed for voltage change, a small current supplying capability and a small electric power consumption rate. One of these voltage dropping circuits
105
and
106
is appropriately operated.
For example, in cases where low electric power consumption is required of the semiconductor device
101
, an output section of the secondary voltage dropping circuit
106
is used as a voltage supply for the internal circuit
104
to reduce electric power consumed in the main voltage dropping circuit
105
. In addition, in cases where the voltage applied to the secondary voltage dropping circuit
106
by the power supply IC
102
is lowered, electric power consumed in secondary voltage dropping circuit
106
can be more reduced.
In contrast, the second method is generally adopted for an IC having no dropping circuit, and a power supply IC of two-voltage supply type is used in the second method. In this two-voltage supply type power supply IC, a voltage source of a high voltage such as 5V and a voltage source of a low voltage such as 3.3V are arranged. Electric power of the high voltage of 5V is supplied for an input/output section of a semiconductor device, and electric power of the low voltage of 3.3V is for an internal circuit of a semiconductor device. To set the two-voltage supply type power supply IC in a semiconductor device, the two-voltage supply type power supply IC has a high voltage outputting section and a low voltage outputting section. Electric power of the high voltage is supplied from the high voltage outputting section to the input/output section of the semiconductor circuit, and electric power of the low voltage is supplied from the low voltage outputting section to the internal circuit. In-this case, electric power consumed in the internal circuit connected with the low voltage outputting section is larger than that consumed in the input/output section connected with the high voltage outputting section. Therefore, a voltage dropping function is added to the low voltage outputting section to obtain a low electric power consumption rate. In contrast, even though the high voltage is dropped in the high voltage outputting section, the reduction of electric power consumption rate in the input/output section is low. Therefore, no voltage dropping function is usually added to the high voltage outputting section.
Because the conventional semiconductor device has the above-described configuration, in cases where the conventional semiconductor device
101
shown in
FIG. 8
is connected with the two-voltage supply type power supply IC according to the second method, it is required to select either a connection of the high voltage outputting section (5V) of the power supply IC with the power supply terminal
103
of the semiconductor device
101
or a connection of the low voltage outputting section (3.3V) of the power supply IC with the power supply terminal
103
of the semiconductor device
101
. Therefore, it is required to arrange a switch as a selecting means in the outside of the semiconductor device
101
, and there is a problem that this results in increases in manufacturing costs for a power supply system composed of a (What is “e”?) two-voltage supply type power supply IC and the semiconductor device
101
. Also, in cases where the conventional semiconductor device
101
is connected with the one-voltage supply type power supply IC according to the first method or is connected with the two-voltage supply type power supply IC according to the second method, because electric power is supplied from the power supply IC
102
to the main voltage dropping circuit
105
and the secondary voltage dropping circuit
106
, there is a problem that more electric power is consumed in the power supply system.
SUMMARY OF THE INVENTION
A main object of the present invention is to provide,
Hashimoto Hiroyuki
Sugita Mitsuru
Burns Doane , Swecker, Mathis LLP
Le Vu A.
Mitsubishi Denki & Kabushiki Kaisha
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