CN1223139C - Programme-controlled switching system user line interface integrating method and circuit - Google Patents
Programme-controlled switching system user line interface integrating method and circuit Download PDFInfo
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- CN1223139C CN1223139C CN 02126697 CN02126697A CN1223139C CN 1223139 C CN1223139 C CN 1223139C CN 02126697 CN02126697 CN 02126697 CN 02126697 A CN02126697 A CN 02126697A CN 1223139 C CN1223139 C CN 1223139C
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Abstract
The present invention relates to a method and a circuit for integrating subscriber line interfaces of a stored program control (SPC) exchange in voice communication. The present invention is characterized in that a terminal interface processor (TIP) driver receives an AC (alternate current) signal from a voice coding / decoding (CODEC) chip, and the DC (direct current) potential of the AC signal is controlled by a DC reference potential generated internally; after the phase reversal and the amplification of the AC signal output by the TIP driver by an RING driver, the AC signal is output to reach the output of a differential signal with two-line balance; at the same time, the DC potential at the output end of the RING driver is determined according to the DC potential of the output end of the TIP driver; the currents of the TIP driver and the RING driver are sampled through a sampling circuit; after an output signal of the sampling circuit passes through a voltage-isolating capacitor, the output signal is sent to the voice CODEC chip; the DC signal output by the sampling circuit is fed back to the RING driver through a limited current circuit; the limited current control of the limited current circuit enables the electrical potential of the output end of the RING driver to increase, relevant increased power is absorbed through an exterior energy consumption device. The present invention has the advantages of low cost, small power consumption and high performance.
Description
Technical field
The present invention relates to telephone communication, relate in particular to a kind of programme-controlled switching system user line interface integrating method and circuit.
Background technology
As shown in Figure 1; the basic schematic diagram of stored-program control exchange user side; subscriber's telephone line enters into Subscriber Line Interface Circuit through the protection device of overcurrent-overvoltage; finish the 2/4 line conversion of necessity by Subscriber Line Interface Circuit after; deliver to the encoding and decoding that phonetic codec chip carries out AD, DA conversion and A/u rule, arrive the pulse code modulation high speed channel PCM Highway of numeral at last.
Protection device, Subscriber Line Interface Circuit, phonetic codec chip and other additional device are finished these seven functions of BORSCHT jointly:
B:Battery Feeding DC feedback;
0:Overvoltage Protecting Overcurrent Protecting over-voltage over-current protection;
The R:Ring ring;
S:Supervise detection loop state;
C: phonetic codec chip Codec encoding and decoding;
H:Hybrid balance combined balance system;
The T:Testing test;
Subscriber Line Interface Circuit also abbreviates SLIC as, i.e. Subscriber Line InterfaceCircuit, and phonetic codec chip also abbreviates CODEC as, i.e. COding DECoding.
Along with the popularization and application of stored-program control exchange, the solution of novel Subscriber Line Interface Circuit also continues to bring out, early stage Subscriber Line Interface Circuit, be to carry out the thick film circuit that alternating current-direct current is isolated with transformer, function is simpler, and volume is big, and some transmission objectives are also more critical.In the nineties, the thick film circuit that has occurred the cancellation transformer again, as introducing in the patent 97208689, but this scheme only is applicable to thick film, and this device is the feed characteristic of constant-current type, make that current source is saturated under long loop situation, can't carry out the voice signal transmission, the on-hook transfer function also need increase extra circuit could be realized, subscriber line interface IC circuit can be finished the function of relative complex, but because Subscriber Line Interface Circuit is a high-tension circuit, complicated function needs more chip area, and cost is higher.
Along with the development of phonetic codec chip technology, the impedance that the phonetic codec chip CODEC of built-in DSP can cooperate user interface circuit SLIC to finish originally must to finish in Subscriber Line Interface Circuit and the function of echo payment.
Because the direct current of user terminal is provided by Subscriber Line Interface Circuit, for the size of direct current, for example that the Chinese national standard regulation is minimum 18mA, and the user can wish to have bigger direct current to provide usually, for example 25mA, even 35mA.And in actual applications, the length of subscriber's line and impedance situation are uncertain, under the situation of big electric current short loop, the power consumption of chip internal will be bigger, the IC scheme of existing Subscriber Line Interface Circuit, because consideration to power consumption, basically need to adopt than relatively large encapsulation TQFP44 for example, the encapsulation of types such as PLCC28 is so that chip can bear higher power consumption in the short loop situation, like this, the volume of chip is bigger, packaging cost is expensive, also takies more pcb board area, thereby has limited the capacity of veneer.
In order to satisfy the chip internal power consumption under the various situations, will adopt relative thermal resistance less, package dimension is bigger, or some more special encapsulation.For example TQFP44 is of a size of 12mm*12mm, and thermal resistance is low, pin is many, and price is expensive, PLCC28, be of a size of 12.4mm*12.4mm, thermal resistance is medium, and price is expensive slightly, perhaps PDSO20 is the special package that metal fin is arranged in a kind of encapsulation, 15.9*14.2mm, thermal resistance is extremely low, and price is very expensive, and the cost of encapsulation can increase so on the one hand, Feng Zhuan size is bigger on the other hand, and the area that takies pcb board is relatively large, is unfavorable for improving veneer density.
Summary of the invention
The object of the present invention is to provide a kind of cost is low, power consumption is little programme-controlled switching system user line interface integrating method and circuit.
The technical solution adopted in the present invention is: this programme-controlled switching system user line interface integrating method is characterized in that: comprise the steps:
A, plug tip TIP driver receive the AC signal from phonetic codec chip CODEC, the direct current reference potential control that its DC potential is produced by inside; AC signal by the output of TIP driver is amplified back output at plug ring RING driver by paraphase, reaches the differential signal output of 2 line balances, simultaneously, according to the DC potential of TIP driver output end, the DC potential of decision RING driver output end;
B, TIP line and RING line are carried out current sample by sample circuit, the output signal of sample circuit is through behind the capacitance, deliver to phonetic codec chip CODEC, the direct current signal of sample circuit output feeds back to the RING driver by a current-limiting circuit, the Current limited Control of current-limiting circuit promotes RING driver output end current potential, shares the power of Promotion From Within by outside energy-dissipating device.
The AC signal of described sample circuit output feeds back to described TIP driver through impedance matching;
The step that described outside energy-dissipating device is shared the power of Promotion From Within is that described outside energy-dissipating device adopts outside power resistor serial connection Zener diode between described RING driver output end and external electric pressure side VBAT;
The positive input terminal current potential of described RING driver is half of external voltage terminal voltage under non-limited current state, by Current limited Control, determines whether promoting the positive input terminal current potential of RING driver;
This programme-controlled switching system user line interface integrating circuit, comprise TIP operational amplifier tipDriver, be used to receive AC signal from phonetic codec chip CODEC, sampling operational amplifier sampleOPA, be used for TIP and RING current sample and convert voltage to, through behind the capacitance, deliver to phonetic codec chip CODEC, it is characterized in that:
Also comprise RING operational amplifier ringDriver, be used for output is amplified in the AC signal paraphase of TIP operational amplifier tipDriver output, TIP operational amplifier tipDriver anode inserts an inner direct current reference potential VREF, and its output is connected to RING operational amplifier ringDriver negative terminal by resistance;
The output of sampling operational amplifier sampleOPA connects a current-limiting circuit, and this current-limiting circuit passes to RING operational amplifier ringDriver anode;
Be connected in series the power resistor RTH of a Zener diode D1 and an outside between RING operational amplifier ringDriver output and the voltage end VBAT;
Described sampling operational amplifier sampleOPA utilizes sampling resistor R
S1, R
S2TIP line and RING line are carried out current sample respectively;
The output of described sampling operational amplifier sampleOPA links to each other with TIP operational amplifier tipDriver anode by another capacitance serial connection feedback resistance;
Described RING operational amplifier ringDriver anode connects filter resistance RLIM and filter capacitor CLIM, constitutes low-pass first order filter.
Beneficial effect of the present invention is: in the present invention, the RING driver is connected into the form of inverting amplifier, is amplified the back in the output of RING end by the interchange of TIP driver output by paraphase, thereby has realized the differential signal output of 2 line balances; Pass through current-limiting circuit, reduce TIP, the DC potential difference of RING two lines, thereby reached the purpose of current limliting, simultaneously, effectively be reduced in the power consumption of chip internal under the short loop situation by the method for external power resistor, thereby allow chip to adopt more small-sized and more cheap standard packaging, thereby reduced chip cost, and help improving veneer density, such resistance can be integrated in Chip-R or thick film multichannel, this thick-film resistor cost is very low, and it is less to take the pcb board area, and peripheral cell required for the present invention is few, the internal circuit small scale, only the scale of 3～4 amplifiers has very big advantage, therefore on cost, cost of the present invention is low and power consumption is little, the AC signal of sample circuit output feeds back to the TIP driver through impedance matching, can show the AC impedance coupling, and operational amplifier sampleOPA utilizes sampling resistor R
S1, R
S2TIP and RING are carried out current sample respectively, circuit structure is simple, cost is low, the low pass filter that capacitor C LIM and resistance R LIM constitute disturbs the ripple on the VBAT and carries out filtering, improve supply-voltage rejection ratio PSRR, the influence of AC feedback signal during also filtering current limliting in addition further improves performance of the present invention.
Description of drawings
Fig. 1 is the basic schematic diagram of stored-program control exchange user side;
Fig. 2 is a circuit diagram of the present invention;
Fig. 3 is the current limliting principle schematic;
Fig. 4 is for reducing chip internal power consumption principle schematic;
Fig. 5 for chip internal power consumption after connecting power resistor with external loop-around resistance variations schematic diagram.
Embodiment
With embodiment the present invention is described in further detail with reference to the accompanying drawings below:
With reference to figure 1, according to Fig. 2, Fig. 3 and Fig. 4, the present invention includes TIP operational amplifier tipDriver, receive AC signal from phonetic codec chip CODEC, sampling operational amplifier sampleOPA utilizes sampling resistor R to TIP and RING
S1, R
S2TIP and RING are carried out current sample respectively and convert voltage to, through behind the capacitance, deliver to phonetic codec chip CODEC, also comprise RING operational amplifier ringDriver, output is amplified in AC signal paraphase to TIP operational amplifier tipDriver output, TIP operational amplifier tipDriver anode inserts an inner direct current reference potential VREF, TIP operational amplifier tipDriver output is connected to RING operational amplifier ringDriver negative terminal by resistance, the output of sampling operational amplifier sampleOPA links to each other with TIP operational amplifier tipDriver anode by another capacitance serial connection corresponding resistor, the output of sampling operational amplifier sampleOPA also connects a current-limiting circuit, this current-limiting circuit passes to RING operational amplifier ringDriver anode, be connected in series the power resistor RTH of a Zener diode Dl and an outside between RING operational amplifier ringDriver output and the voltage end VBAT, RING operational amplifier ringDriver anode connects resistance R LIM and capacitor C LIM, constitutes low-pass first order filter.
TipDriver has realized the fixedly stack of DC potential and VRX signal and impedance matching feedback signal, and as shown in Figure 2, tipDriver is connected into the form of operational amplifier, can calculate:
The voltage V of TF end points
TF=V
VREF+ V
CZL-V
VRX
Wherein VREF is the direct current reference potential that chip internal produces, it has determined the voltage of TF end points, in order to guarantee the transmittability of certain AC signal, VREF is generally-3.5V about, and the signal that AC signal and impedance matching from phonetic codec chip CODEC that VRX and CZL are respectively 4 lines to be sent into feed back to.
Like this, the DC potential of tipDriver under any circumstance, loop length no matter, substation dislodging machine, it all is that relative fixed is constant.
RingDriver is connected into the form of inverting amplifier, and the voltage that TIP is sent carries out the paraphase amplification, has realized the transmission to difference AC signal so on the one hand, in addition, also according to the DC potential of TF end, has determined the DC potential of RF end.
V
RF＝2×V
VM-V
TF
When not having limited current state under long loop situation or substation when being in hook state, VM is VBAT/2,
Then, V
RF=V
VBAT-V
TF
Under needs current limliting situation, VM promotes, and then the current potential of RF end promotes thereupon, and the pressure reduction of TF and RF two-port diminishes, thereby has reduced the external loop-around electric current.
The low-pass first order filter that capacitor C LIM and resistance R LIM constitute, on the one hand the ripple on the outside voltage end VBAT is disturbed and carry out filtering, improve supply-voltage rejection ratio PSRR, exchange the influence of feedback signal in addition during also filtering current limliting, one filter to get, in order further to improve filter effect, also can adopt the form of Order RC filtering.
As seen from the above analysis, again with reference to figure 1, the present invention can finish the conversion from 4 lines to 2 lines.
Because above-mentioned 4 lines are the voltage form feed to the feed form of 2 lines, carry out current sample at 2 lines to the conversion of 4 lines, as shown in Figure 2, resistance R s1 and Rs2 are external sampling resistor, utilize sampleOPA, and the electric current of two lines of sampling also converts voltage to, sampleOPA output VTX signal, the VTX voltage of signals is just delivered to phonetic codec chip CODEC through behind the capacitance, finishes the conversion of 2 lines to 4 lines.
The output of VTX signal is delivered in the current-limiting circuit, as shown in Figure 3, current-limiting circuit is connected on the positive input terminal of RING driver, under non-limited current state, the positive input terminal current potential of RING driver is VBAT/2, controls by current-limiting circuit, determine whether the positive input terminal current potential of lifting RING driver, thereby influence the output DC position of RING driver, and then reduce the DC potential difference of TIP, RING two lines, thereby reached the effect of current limliting.
Because the output DC position of Tip Driver is fixed, the size of the direct current of loop decides the generation of Current limited Control electric current or does not produce, and as loop direct current Idcloop during less than certain threshold value, Tctl is O, the VM terminal potential is exactly VBAT/2, when loop direct current during greater than threshold value, Ictl increases, as can be seen, the current potential of VM promotes, thereby the RF current potential promotes, and has dwindled the pressure reduction of external loop-around, thereby has reduced electric current.
But under short loop, though the restriction that ILoop obtains,, because the lifting of ringDriver current potential, the power consumption that consumes at chip internal has increased.
For example, loop current 25mA, external loop-around resistance 400ohm, VBAT=-54V, then chip internal is owing to the power consumption that loop current produces is: (54V-25mA*400ohm) * 27mA=1188mW, add the quiescent dissipation of other circuit, about 100mW, then the chip internal power consumption has reached about 1288mW, the thermal resistance ability to bear that has exceeded general encapsulation, under the operational environment of high temperature, the chip internal temperature has surpassed range of safety operation if the packaging thermal resistance of selecting is too big!
In order to reduce the power consumption of chip internal, the Zener diode D1 of an inside, one terminates at the RING output end of driver, the external external power resistance R of one end TH, its effect is, utilize the conducting of Zener diode D1 to need certain conducting voltage, so when chip is in hook state, just there is not quiescent current to flow through the resistance of outside, it has reduced the power consumption when loop is in hook state, and when the loop off-hook and when being short loop, it again conducting provide electric current to flow out among the external power resistance R TH.
As shown in Figure 4, the Zener diode D1 that connects the RFEED pin is positioned at chip internal, characteristic by Zener diode can be known, after the RF end exceeds the reverse breakdown voltage Vbr (about about 5V) of zener than VBAT current potential, Zener diode D1 conducting, begin to have electric current to flow through, can bear bigger power consumption from external power resistor RTH.When VRF-VBAT＞Vbr, the power consumption of being shared by external power resistor RTH is P=(VRF-VBAT-Vbr)
2/ RTH, can see, the RF terminal potential promotes highly more, the electric current of the external power of then flowing through resistance R TH is big more, then the power consumption of externally sharing on the power resistor RTH is also big more, and the maximum power dissipation ability of bearing according to chip internal and the maximum current and the minimum load of loop can calculate the resistance of required power resistor RTH, and the power consumption of on power resistor RTH, sharing, and select optimal value in view of the above.
For example, loop current limliting 25mA, RTH is chosen as 2K, and the puncture voltage of supposing Zener diode is 5V, at this moment the interior power consumption of chip is with the variation of outside loop resistance, as shown in Figure 5, add that the chip internal power consumption can be seen with the schematic diagram of external loop-around resistance variations behind the power resistor RTH, the power consumption of chip internal is by original maximum 1288mW, be reduced to about 520mW, the power consumption of chip internal reduces widely, has reduced the power consumption of chip internal effectively.
As seen,, reduced the power consumption of chip internal effectively, like this, on the one hand improved chip reliability, on the other hand, also can select cheap and the more encapsulation of miniaturization, thereby improved the density of veneer by the RFEED external shunt.
Can reach the true impedance coupling of inner certain resistance among the present invention, 600ohm for example can be finished the coupling of all the other complex impedances easily by phonetic codec chip CODEC.
By above analysis as can be known, the present invention can finish following function:
1. the conversion of the 2-4 line between four lines of two lines of realization user interface circuit SLIC and phonetic codec chip CODEC;
2. the DC feedback characteristic of voltage feed, current feedback type realizes long loop constant voltage, the DC feedback current-limiting function of short loop constant current;
3. the form of voltage feed is supported the on-hook transfer function.
Claims (8)
1. a programme-controlled switching system user line interface integrating method is characterized in that: comprise the steps:
A, plug tip TIP driver receive the AC signal from phonetic codec chip CODEC, the direct current reference potential control that its DC potential is produced by inside; AC signal by the output of TIP driver is amplified back output at plug ring RING driver by paraphase, reaches the differential signal output of 2 line balances, simultaneously, according to the DC potential of TIP driver output end, the DC potential of decision RING driver output end;
B, TIP line and RING line are carried out current sample by sample circuit, the output signal of sample circuit is through behind the capacitance, deliver to phonetic codec chip CODEC, the direct current signal of sample circuit output feeds back to the RING driver by a current-limiting circuit, the Current limited Control of current-limiting circuit promotes RING driver output end current potential, shares the power of Promotion From Within by outside energy-dissipating device.
2. programme-controlled switching system user line interface integrating method according to claim 1 is characterized in that: the AC signal of described sample circuit output feeds back to described TIP driver through impedance matching.
3. programme-controlled switching system user line interface integrating method according to claim 1, it is characterized in that: the step that described outside energy-dissipating device is shared the power of Promotion From Within is that described outside energy-dissipating device adopts outside power resistor serial connection Zener diode between described RING driver output end and external electric pressure side VBAT.
4. programme-controlled switching system user line interface integrating method according to claim 3, it is characterized in that: the positive input terminal current potential of described RING driver is half of external voltage terminal voltage under non-limited current state, by Current limited Control, determine whether promoting the positive input terminal current potential of RING driver.
5. programme-controlled switching system user line interface integrating circuit, comprise TIP operational amplifier tipDriver, be used to receive AC signal from phonetic codec chip CODEC, sampling operational amplifier sampleOPA, be used for TIP and RING current sample and convert voltage to, through behind the capacitance, deliver to phonetic codec chip CODEC, it is characterized in that:
Also comprise RING operational amplifier ringDriver, be used for output is amplified in the AC signal paraphase of TIP operational amplifier tipDriver output, TIP operational amplifier tipDriver anode inserts an inner direct current reference potential VREF, and its output is connected to RING operational amplifier ringDriver negative terminal by resistance;
The output of sampling operational amplifier sampleOPA connects a current-limiting circuit, and this current-limiting circuit passes to RING operational amplifier ringDriver anode;
Be connected in series the power resistor RTH of a Zener diode (D1) and an outside between RING operational amplifier ringDriver output and the voltage end VBAT.
6. programme-controlled switching system user line interface integrating circuit according to claim 5 is characterized in that: described sampling operational amplifier sampleOPA utilizes sampling resistor (R
S1, R
S2) TIP line and RING line are carried out current sample respectively.
7. according to claim 5 or 6 described programme-controlled switching system user line interface integrating circuit, it is characterized in that: the output of described sampling operational amplifier sampleOPA links to each other with TIP operational amplifier tipDriver anode by another capacitance serial connection feedback resistance.
8. programme-controlled switching system user line interface integrating circuit according to claim 5 is characterized in that: described RING operational amplifier ringDriver anode connects filter resistance RLIM and filter capacitor CLIM, constitutes low-pass first order filter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02126697 CN1223139C (en) | 2002-07-27 | 2002-07-27 | Programme-controlled switching system user line interface integrating method and circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02126697 CN1223139C (en) | 2002-07-27 | 2002-07-27 | Programme-controlled switching system user line interface integrating method and circuit |
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| Publication Number | Publication Date |
|---|---|
| CN1471261A CN1471261A (en) | 2004-01-28 |
| CN1223139C true CN1223139C (en) | 2005-10-12 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 02126697 Expired - Fee Related CN1223139C (en) | 2002-07-27 | 2002-07-27 | Programme-controlled switching system user line interface integrating method and circuit |
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| CN (1) | CN1223139C (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101860330B (en) * | 2010-04-14 | 2012-09-05 | 华为技术有限公司 | Amplifying unit, power amplifier and transmitter |
| CN112835281B (en) * | 2021-01-13 | 2023-07-28 | 珠海奔图电子有限公司 | Communication chip, consumable and image forming apparatus |
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| CN1471261A (en) | 2004-01-28 |
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