CN2520081Y

CN2520081Y - Power source for coordinate circuit of data interface of external modem

Info

Publication number: CN2520081Y
Application number: CN 01274783
Authority: CN
Inventors: 林少锋; 梁小霞
Original assignee: Lenovo Beijing Ltd
Current assignee: Lenovo Beijing Ltd
Priority date: 2001-12-28
Filing date: 2001-12-28
Publication date: 2002-11-06
Anticipated expiration: 2011-12-28

Abstract

The utility model relates to a power source for a coordinate circuit of a data interface of an external modem. Power source input is a digit signal electricity taking end, the output of which is isolated by a transformer and then is connected with a rectification circuit to a power source output end, wherein the digit signal electricity taking end is a clock signal or a serial port signal. The rectification circuit is a half-wave rectification circuit. A DAA circuit power source of the utility model takes electricity from a signal wire of a digital circuit, is coupled to a DAA end by a transformer, and supplies electricity to a DAA circuit. The DAA circuit gets out of the digital circuit to take electricity, but is not connected with an electricity supplying source of the digital circuit and the ground so as to avoid the interference to the digital circuit from a DAA high-voltage circuit which is directly brought to the DAA circuit by a power source of a digital system and avoid taking electricity from a telephone line and the dependence on the signal quality of the telephone line of the work performance of the MODEM.

Description

External modem data-interface coordination portion circuit power

Technical field:

The utility model relates to a kind of this technology circuit power supply, especially a kind of external serial port modem data-interface coordination portion (DAA) circuit power that belongs to.Belong to electronic technology field.

Background technology:

The quality of DAA part power supply design will directly influence the stability and the transmission rate of modulator-demodulator (MODEM).The design of the power supply of the DAA partial circuit of existing MODEM mainly contain the telephone wire power taking to DAA circuit supply and numeral (DSP part) system power supply directly to the DAA circuit supply.These two kinds of schemes all influence the serviceability of MODEM inevitably.

As shown in Figure 1.With the signal rectification on the telephone wire, filtering, isolate the DC component in the back extraction signal among Fig. 1, after simple again step-down is handled, give the DAA chip power supply.Simultaneously, on the telephone wire alternating current component, handle the input signal of back as DAA.Because the DAA chip is powered by the mode of power taking on the telephone wire fully, the stability of MODEM when work DAA circuit working whether the stablizing of telephone wires signals that place one's entire reliance upon.Telephone signal in Chinese telephone signal, particularly Chinese countryside is second-rate, this supply power mode be MODEM when working in the such kind of area performance will reduce greatly.

As shown in Figure 2, for digital system power supply in the prior art to the typical circuit of DAA circuit supply.The digital system power supply directly to the characteristics of the circuit of DAA circuit supply with not enough: since the signal of DAA partial circuit be telephone wires signals be relatively high pressure signal about 70V.The high-voltage signal of DAA will directly influence the speed of MODEM to the interference of numerical portion dsp chip.Therefore, another technical barrier of external serial ports MODEM is how to avoid the interference of the high-voltage signal of DAA end to the numerical portion signal.Shown in Figure 2, digital power is digital power (VDD shown in the figure) to be isolated the back by inductance produce AVDD to the DAA chip power supply, like this with inevitable DAA circuit and digital circuit common-battery source and power supply to the characteristics of the circuit of DAA circuit supply.Like this, the interference of the high-tension circuit of DAA part will be inevitably by power supply and be coupled to the digital circuit end, influence the work of dsp chip, directly influence the performances such as transmission rate of MODEM.

Summary of the invention:

The purpose of this utility model is to provide a kind of External modem data-interface coordination portion circuit power, it does not rely on the quality of telephone wires signals, and the problem that does not have signal to disturb can ensure the stability of DAA circuit working and the transmission rate of MODEM.

For this reason, the utility model is achieved through the following technical solutions above-mentioned purpose:

A kind of External modem data-interface coordination portion circuit power, power supply is input as digital signal power taking end, and this end output connects rectification circuit to power output end by transformer.Wherein said digital signal power taking end is clock signal or rs 232 serial interface signal.Described rectification circuit is a half-wave rectifying circuit.

According to technique scheme, the utility model is with the clock signal (PWRCLKN in the digital circuit, PWRCLKP) mode by the transformer coupling produces an AC signal at the DAA end, and again by halfwave rectifier, filtering produces tributary power supply signal AVDD and gives the DAA circuit supply.Like this can be fully with the power supply of numerical portion, the power supply ground of ground and DAA part keeps apart, and avoids the interference of DAA high-voltage signal to digital circuit.Simultaneously, because the DAA circuit has the numerical portion power supply, when having avoided phone-line-powered, the bad influence of telephone wires signals to the MODEM service behaviour.

Description of drawings

Fig. 1 is from phone-line-powered circuit theory diagrams in the prior art;

Fig. 2 is from the circuit theory diagrams of digital circuit power taking in the prior art;

Fig. 3 is the utility model circuit theory diagrams.

Embodiment:

Referring to Fig. 3, the utility model is a kind of External modem data-interface coordination portion circuit power.Power supply is input as the clock signal PWRCLKN in the digital circuit, PWRCLKP, and this end is exported this transformer T2 through resistance R 110, R112.Mode by transformer T2 coupling produces an AC signal, this AC signal is by half-wave rectifying circuit D2, D4 and resistance R 124, capacitance group C70, C72, C28 etc., filtering produces tributary power supply signal AVDD and gives the DAA circuit supply, thereby fully with the power supply of numerical portion, the power supply of ground and DAA part, keep apart.Avoid of the interference of DAA high-voltage signal to digital circuit.Simultaneously, because the DAA circuit has the numerical portion power supply, when having avoided phone-line-powered, the bad influence of telephone wires signals to the MODEM service behaviour.

In sum, DAA circuit power of the present utility model is coupled to the DAA end from the power taking of Digital Circuit Signal line by a transformer, gives the DAA circuit supply.The DAA circuit go out the digital circuit power taking, but not with digital circuit power supply source and ground.So promptly can avoid the digital system power supply directly to give the interference to digital circuit of DAA high-tension circuit that the DAA circuit causes, can avoid the telephone wire power taking again, the MODEM service behaviour is to the dependence of telephone wires signals quality.

It should be noted last that, above embodiment is only unrestricted in order to explanation the utility model, although the utility model is had been described in detail with reference to preferred embodiment, those of ordinary skill in the art is to be understood that, can make amendment or be equal to replacement the utility model, and not breaking away from spirit and scope of the present utility model, it all should be encompassed in the middle of the claim scope of the present utility model.

Claims

1, a kind of External modem data-interface coordination portion circuit power, it is characterized in that: power supply is input as digital signal power taking end, and this end output connects rectification circuit to power output end by after transformer coupled.

2, External modem data-interface coordination portion circuit power according to claim 1, it is characterized in that: described digital signal power taking end is a clock signal.

3, External modem data-interface coordination portion circuit power according to claim 1, it is characterized in that: described digital signal power taking end is a rs 232 serial interface signal.

4, External modem data-interface coordination portion circuit power according to claim 1, it is characterized in that: described rectification circuit is a half-wave rectifying circuit.