Input and output port circuit

Details Input and output port circuit Input and output port circuit

2002-12-23

2004-08-10

Le, Dinh T. (Department: 2816)

Miscellaneous active electrical nonlinear devices, circuits, and

Signal converting, shaping, or generating

Amplitude control

C327S112000

Reexamination Certificate

active

06774697

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates generally to an input and output port circuit. More particularly, the invention relates to an input and output port circuit by which an output driving circuit can be simultaneously driven at a high voltage operation mode and a low voltage operation mode and the output driving circuit can be also selectively driven since they are also constructed in a multiple stage.
2. Description of the Prior Art
An input and output port circuit serves to output signals generated within a chip to the outside through an input/output pad or to transfer the signals inputted through the input/output pad to the chip.
Referring now to
FIG. 1
, a construction of a conventional input and output port circuit will be below described.
A two-input low voltage NAND gate
11
functions to logically combine a value of a signal register (SIGR) and a value of an input/output register (DIRR) that is inverted by an inverter I
11
. A two-input low voltage NOR gate
12
serves to logically combine the value of the signal register (SIGR) and the value of the input/output register (DIRR). At this time, the signal register (SIGR) stores output signals and the input/output register (DIRR) stores an input/output control signal for determining an input/output direction. A PMOS transistor P
11
of a large size is connected between a low voltage (VDDL) output terminal (a logical value “1”) and a pad (PAD), thereby being driven depending on the output of the two-input low voltage NAND gate
11
. A NMOS transistor N
11
is connected between the pad (PAD) and the ground (GND) (a logical value “0”) and is also driven depending on the output of the two-input low voltage NOR gate
12
. The PMOS transistor P
11
and the NMOS transistor N
11
are output driving transistors. Meanwhile, all of the circuits are constructed to perform a normal voltage operation.
A method of driving the conventional input and output port circuit constructed above will be described.
If the value of the input/output register (DIRR) is the logical value “1” (VDDL), the two-input low voltage NAND gate
11
outputs the logical value “1” (VDDL) and the two-input low voltage NOR gate
12
outputs the logical value “0”, regardless of the value of the signal register (SIGR). Therefore, the input signal is inputted by the input path, since both the transistors P
11
and N
11
are turned “OFF” by the outputs of the two-input low voltage NAND gate
11
and the two-input low voltage NOR gate
12
, respectively.
Meanwhile, if the value of the input/output register (DIRR) is the logical value “0”, its output is determined depending on the value of the signal register (SIGR). If the value of the input/output register (DIRR) is the logical value “0” and the value of the signal register (SIGR) is the logical value “1” (VDDL), the two-input low voltage NAND gate
11
outputs the logical value “0” and the two-input low voltage NOR gate
12
also outputs the logical value “0”. As a result, the PMOS transistor P
11
is turned “ON” and the NMOS transistor N
11
is turned “OFF”, so that the low voltage (VDDL) is outputted through the pad (PAD).
Further, if the value of the input/output register (DIRR) is the logical value “0” and the value of the signal register (SIGR) is the logical value “0”, the two-input low voltage NAND gate
11
outputs the logical value “1” (VDDL) and the two-input low voltage NOR gate
12
also outputs the logical value “1” (VDDL). As a result, the PMOS transistor P
11
is turned “OFF” and the NMOS transistor N
11
is turned “ON”, so that the value of the ground (GND) is outputted through the pad (PAD).
It is required that the output driving transistor of the conventional input and output port circuit be constructed to have a very large size, in order to drive a load of a large capacitance. With this construction, a large amount of power consumption is required. In addition, in order to drive the high voltage, one additional input and output port circuit for use in the high voltage is required since the conventional output driving transistor is driven only at the low voltage.
SUMMARY OF THE INVENTION
The present invention is contrived to solve the above problems and an object of the present invention is to provide an input and output port circuit capable of simultaneously driving a high voltage and a low voltage using a single output driving circuit.
Another object of the present invention is to provide an input and output port circuit in which a single output driving circuit is constructed in a multiple stage and is thus selectively driven by an output control register, thus reducing the power consumption.
In order to accomplish the above object, the input and output port circuit according to the present invention, is characterized in that it comprises a signal register for storing output signals; an input/output register at which input/output control signals for determining an input/output direction are stored, a plurality of control registers, a power supply switch circuit for selectively supplying a low voltage or a high voltage depending on a power mode control signal, a signal direction control circuit connected to the signal register and the input/output register for determining the direction of a signal to be inputted or outputted through an input/output pad depending on a value of the signal register and a value of the input/output register, an output control circuit connected to the signal direction control circuit and the control register and driven depending on a value of the control register and output signals of the signal direction control circuit, and an output driving circuit connected to the output control circuit and the power supply switch circuit for outputting the low voltage, the high voltage or a ground value depending on the output signals of the signal direction control circuit and output signals of the output control circuit.
Furthermore, the input and output port circuit of the present invention comprises a power supply switch circuit for selectively supplying a low voltage or a high voltage depending on a power mode control signal that determines a normal voltage operation mode or a high voltage operation mode, a high voltage NAND gate for logically combining a value of a signal register and a value of an input/output register that is inverted by a first high voltage inverter, a high voltage NOR gate connected to the signal register and the input/output register for logically combining a value of the signal register and the value of the input/output register, a high voltage OR gate for logically combining an output of the high voltage NAND gate and a value of a control register that is inverted by a second high voltage inverter, a high voltage AND gate connected to the high voltage NOR gate and the control register for logically combining an output of the high voltage NOR gate and the value of the control register, and an output driving circuit connected between the power supply switch circuit and the around and constructed with a plurality of output driving circuits, wherein the output driving circuits are driven depending on output signals of the high voltage NAND gate, the high voltage NOR gate, the high voltage OR gate and the high voltage AND gate to output the low voltage, the high voltage or the ground value.


REFERENCES:
patent: 5821800 (1998-10-01), Le et al.
patent: 6225824 (2001-05-01), Madhu et al.
patent: 6240030 (2001-05-01), Kang et al.
patent: 6323704 (2001-11-01), Pelley et al.
patent: 6512401 (2003-01-01), Clark et al.
patent: WO 01/18967 (2001-03-01), None

Affiliated with

Also associated with

Rating

Input and output port circuit does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Input and output port circuit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Input and output port circuit will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3355134