JPH0332223A - Output circuit - Google Patents

Abstract

PURPOSE:To reduce output noise by providing a TR in series with an output driver TR, and suppressing an excess current by the said TR. CONSTITUTION:With an L input from an output control signal terminal 2, TRs 4, 5 are turned on and when an H signal is inputted from an input signal terminal 1, the TR 4 is turned on. A voltage of a power potential-(2Xthreshold voltage) is applied to the gate of a TR 13 from a constant voltage generating circuit 1, the TR 13 reaches a saturation current lower than that of the TR 4 to suppress the current supplied from the power terminal to the TR 4. Even when an L signal is inputted from the input signal terminal 1, the TR 5 is turned on and a voltage of a GND level + (2X threshold voltage) is supplied to the gate of the TR 14 from the constant voltage generating circuit 16 to suppress the current. Thus, excess current is suppressed and a cause of noise is eliminated.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an output circuit for a semiconductor device.

[Conventional technology]

FIG. 8 is a circuit diagram of an output circuit of a conventional semiconductor device. IIM dynamic P-type transistor 51 is 1p // drive N-type transistor, +611-1 power supply terminal, (7) po GND terminal, (81 transistors (4) complete control circuit, (9
) is a circuit that controls transistor j5), and tlol is an inverting circuit.

Next, the operation will be explained. When ``H'' is input from the output-specific sub-signal (2), transistors +41 and +51 are OFF.
It becomes F state. From the output control signal (2), when the input is "L", the transistor +41 f5) can be turned on, and when a signal is input from the input signal terminal ill, it is transmitted to the transistors 141 and 151.H
//When the input is large, the P-type transistor (4) is turned on, and the output is supplied with the source potential gold. In addition, when "L' is a large input, the N-type transistor j51 is in the ON state, and the output is GN.
D-potential gold is supplied.

[Problem to be solved by the invention]

Conventional output circuits are configured as described above, so when the output signal is inverted, an excessive current flows instantaneously due to the through current of the transistor VC, causing the L- of the power supply line and output terminal to flow.
The output voltage varies depending on the amount of 01i. There is a problem in that this voltage fluctuation becomes noise and causes malfunctions.

This invention was made to solve the above-mentioned problems, and its purpose is to obtain an output circuit that suppresses excessive current and eliminates the cause of noise.

[Means for solving problems]

In the output circuit according to the present invention, a transistor is provided in series with the output driver transistor, and excessive current that causes noise is suppressed by the transistor 03.

[Effect]

In the output circuit according to the present invention, the current is suppressed and malfunctions are prevented by applying a voltage to the gate of the transistor provided in series with the output driver transistor so that the saturation current is lower than that of the output driver transistor.

[Practice] Hereinafter, the embodiment of this invention i [4J (r diagram) will be explained.

In FIG. 1, the numbers 111 to (10) are 1-1 with the conventional ones. In the diagram, (+3) is a P-type transistor for current control, 041 is a 1N-type transistor for current control, and 00 is a transistor 03)'? This is a constant voltage generation circuit that controls a constant voltage generation circuit (IfIl is a transistor α4).

Next, the operation will be explained. As explained in the conventional output circuit above, the output! 11L I! from 1i-INfflJ signal terminal 12) At the time of large input, the transistor 031151 can be turned on, and the input signal terminal [11
When a “H” signal is input, the transistor 14
) becomes ON state. At this time, the gate of the transistor (13) is supplied with a power supply potential -(
When a voltage of 2 x threshold voltage) is supplied to the button, transistor 03) has a saturation current value lower than the saturation current value of transistor (41), and transistor +4 is supplied from the power supply terminal.
Suppress the current supplied by 1VC. As a result, when the output terminal rises from "L" to "HI/," an excessive current is prevented from flowing momentarily, and the slope of the rise of the output signal is made gentle.

Similarly, when a signal of 1L// is input from the input signal terminal fi+ of the housing, the transistor (5) is turned on, and at this time, the gate of the transistor circle is connected to the GND potential (2).
A voltage of X threshold voltage) is supplied from the constant voltage generation amount WIf+6) to suppress the current and adjust the falling slope of the output signal.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to suppress the instantaneous flow of an excessive current when the output signal is inverted, so that the output noise can be reduced by 4, and the effect of improving the output characteristic sound can be obtained.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an output circuit showing an embodiment of the present invention.
2 is a waveform diagram of the input signal and output signal of FIG. 1, FIG. 3 is a circuit diagram of a conventional output circuit, and FIG. 4 is a waveform diagram of each part of FIG. 8. In the figure, +11 is the input signal terminal, (21
is the output separate picture signal terminal, +31 is the output signal terminal, (4) is the 'lH//drive type transistor +51Viゝ+
L ///Active N-type transistor +61 Lri power supply terminal, +71i G'N D terminal, (8) is transistor 14) Sound control circuit, +91i) Transistor 5) Sound control circuit, (!0) is inverting circuit , 0(1) is a P-type transistor for current control, 0(1) is an N-type transistor for current control, 051 is a constant pressure generation 1 (-1IJ path that controls transistor t+a+', (161 is transistor 1)
The constant voltage generation circuit that controls the In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] In an output driver transistor of a semiconductor device, when an N-type transistor and a P-type transistor are used between a power supply and an output, a current control transistor is provided in series with the transistor to control the current.