KR20000008809U - Low Power Pull-Up and Pull-Down Drive Circuit - Google Patents

Abstract

The present invention is to provide a low-power pull-up and pull-down driving circuit that reduces power consumption by preventing unnecessary pull-up operation, for this purpose, the present invention is an external circuit that receives and drives the output signal from the common output node A pull-up and pull-down drive circuit for eliminating unnecessary pull-up driving by means of: a pull-up for pull-up and pull-down driving the common output node in response to an input signal and a pull-up control signal; Up and pull-down drive means; Output signal detecting means for receiving a feedback input of the output signal from the common output node and detecting a level of the output signal to output a level detection signal; And control signal generating means for outputting the pull-up control signal in response to the level detection signal from the input signal and the output signal detecting means.

Description

Low Power Pull-Up and Pull-Down Drive Circuit

The present invention relates to semiconductor circuits, and more particularly, to pull-up and pull-down drive circuits for driving common output nodes pull-up and pull-down.

In general, pull-up and pull-down driving circuits are commonly used as bus driving circuits.

1 shows a conventional simple pull-up and pull-down driving circuit, in which a pull-up transistor PM1 and a gate connected in series between a power supply voltage terminal and a ground power supply terminal, whose gates are connected to the ground power supply terminal. The pull-down transistor NM1 receives the input signal IN, and is configured to drive the output signal OUT from the common node of the pull-up transistor PM1 and the pull-down transistor NM1.

In the conventional pull-up and pull-down driving circuits as described above, an external driving circuit driven by receiving the output signal OUT after fully charging the output terminal for the output signal OUT to be driven (shown in FIG. (Not shown), there is a problem in that the pull-up transistor PM1 is always turned on and consumes unnecessary power by continuously charging the output terminal.

An object of the present invention is to provide a low-power pull-up and pull-down driving circuit that has been devised to solve the above problem and prevents unnecessary pull-up operation to reduce power consumption.

1 is a conventional simple pull-up and pull-down drive circuit diagram.

2 is an exemplary circuit diagram of a pull-up and pull-down driving circuit according to the present invention.

3 is a signal waveform diagram of the pull-up and pull-down drive circuit of FIG. 2 according to the present invention;

* Description of the main parts of the drawing

200: pull-up and pull-down drive

210: output signal detector

220, 212: NOR gate

230: external drive circuit

C1: Capacitor

R1: resistance

In order to achieve the above object, the present invention provides a pull-up and pull-down driving circuit for eliminating unnecessary pull-up driving by an external circuit that receives and drives an output signal from a common output node. Pull-up and pull-down driving means for pull-up and pull-down driving the common output node in response to an up-control signal; Output signal detecting means for receiving a feedback input of the output signal from the common output node and detecting a level of the output signal to output a level detection signal; And control signal generating means for outputting the pull-up control signal in response to the level detection signal from the input signal and the output signal detecting means.

2 is a circuit diagram of a pull-up and pull-down driving circuit according to the present invention, and includes a pull-up transistor PM2 and a pull-down transistor NM2 to pull-up and output signal OUT1. A pull-up and pull-down driving unit 200 for pull-down driving, an output signal detector 210 for detecting the level of the output signal OUT1 by receiving the output signal OUT1 as a feedback input, and an input signal A NOR gate 220 for outputting a pull-up control signal net1 for controlling the pull-up transistor PM2 in response to the IN and the detection signal net2 from the output signal detector 210; A capacitor C1 connected between an output terminal of the output signal OUT1 and a ground power supply terminal for charging and discharging, a parasitic resistor R1 connected between an output terminal of the output signal OUT1 and a ground power supply terminal, and An external device connected to the output terminal for driving the output signal OUT2 in response to the output signal OUT1. It comprises a circuit portion (230).

Here, the output signal detector 210 receives the output signal OUT1 and receives a delay unit 211 for delaying a predetermined time and an output signal OUT1 and a delayed output signal outputted from the delay unit 211 and receives a negative logic sum. The NOR gate 212 is provided, and the delay unit 211 removes noise such as glitch of the output signal OUT1.

3 is a signal waveform diagram of the pull-up and pull-down driving circuit of FIG. 2 according to the present invention.

2 and 3, an exemplary operation of the pull-up and pull-down driving circuit of the present invention will be described in detail.

First, when the input signal IN falls from "high" to "low", the pull-down transistor NM2 is turned off and "low" pull-through through the NOR gate 220. The up control signal is output and the pull-up transistor PM2 is turned on. At this time, the output terminal of the pull-up and pull-down driving unit 200 starts to be charged "high", and when the capacitor C1, which is the load capacitance, is fully charged, the V _DS of the pull-up transistor PM2 is almost " 0 "will prevent any further charging. However, when a leakage current occurs due to the parasitic resistance R1 and the voltage drop of the output stage occurs, the pull-up transistor charges the thermal capacitor C1 again by the drop amount.

Next, as illustrated in FIG. 3, the external driving circuit 230 that receives and drives the output signal OUT1 from the pull-up and pull-down driving circuits of the present invention is an output signal OUT2 having a "low" level. ), The pull-up transistor PM2 is directly connected to the ground power supply terminal in a turned-on state, and current flows continuously from the power supply voltage terminal to the ground power supply terminal. To prevent this, the output signal detection unit 210 of the present invention detects the value when the output signal OUT1 falls completely "low" to prevent the leakage current by turning off the pull-up transistor PM2. In addition, in order to determine whether the output signal OUT1 is caused by noise, glitch, or the like, the delay unit 211 is removed from the output signal detector 210 to eliminate noise such as round glitches.

Although the technical spirit of the present invention has been described in detail according to the above-described preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, a person of ordinary skill in the art will appreciate that various embodiments are possible within the scope of the technical idea of the present invention.

The present invention made as described above has the effect of reducing the power consumption by detecting the level of the output signal to prevent the pull-up operation of the unnecessary pull-up transistor, and also a circuit embedded in a portable system driven by a battery, etc. Has the additional effect of extending the service life of the system.

Claims (5)

A pull-up and pull-down driving circuit for eliminating unnecessary pull-up driving by an external circuit that receives and drives an output signal from a common output node, Pull-up and pull-down driving means for pull-up and pull-down driving the common output node in response to an input signal and a pull-up control signal; Output signal detecting means for receiving a feedback input of the output signal from the common output node and detecting a level of the output signal to output a level detection signal; And Control signal generation means for outputting the pull-up control signal in response to a level detection signal from the input signal and the output signal detection means Pull-up and pull-down driving circuit comprising a. The method of claim 1, wherein the pull-up and pull-down drive means A pull-up transistor and a pull-down transistor connected in series between a power supply voltage terminal and a ground power supply terminal, respectively receiving the pull-up control signal and the input signal through a gate; Pull-up and pull-down drive circuit comprising a. The method of claim 1, wherein the output signal detecting means, Delay means for receiving an output signal from the common output node and delaying it; And Negative logic means for negating and logically receiving an output signal from the common output node and a signal from the delay means Pull-up and pull-down drive circuit comprising a. The method of claim 1, wherein the control signal generating means Negative logic sum means for receiving the input signal and the level detection signal and performing a negative logic sum Pull-up and pull-down drive circuit comprising a. 2. The apparatus of claim 1 wherein between the common output node and the external circuit A parasitic capacitor connected between the common output node and a ground power supply terminal for charging and discharging; And Parasitic resistance connected between the common output node and the ground power supply terminal Pull-up and pull-down drive circuit further comprising.