L6726_08 UTC | Alldatasheet
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UNISONIC TECHNOLOGIES CO., LTD L6726 LINEAR INTEGRATED CIRCUIT www.unisonic.com.tw 1 of 13 Copyright © 2008 Unisonic Technologies Co., Ltd QW-R108-015,B UNIVERSAL SPEECH CIRCUIT DESCRIPTION The UTC L6726 is a mask-programmable, monolithic integrated speech circuits for using in electronic telephones. It is designed for using with a low impedance microphone. Transmitting and receiving gain are regulated with line length. Different regulation for various current feeds can be set by external resistors. Typica l current feeds as 48V 2·200 Ω, 48V, 2·400Ω, and 36V, 2·500 Ω, can be handled. Application dependent parameters such as line balance, side tone level, amplification and frequency response are set by external components. Parameters are set independently which means easy adaptation for various market needs. The UTC L6726 is developed for using with CMOS-type dialer ICs. A separate DTMF input is switched when the circuit is muted, and an adjustable DC s upply is provided for feeding an external CMOS device. FEATURES *Minimum number of inexpensive external components, 5 capacitors and 11 resistors. *Mute function for operation with DTMF-generator. *Transmit and receive gain regul ation for automatic loop loss compensation. *Extended current and voltage range 5~130mA, down to 2V. *Differential microphone input for good balance to ground. *Balanced receiver output stage. *Short start-up time. *Stabilized DC-supply for low current CMOS dialers and/or electret microphones. *DTMF-input controlled by mute. *Pb-free plating product number: L6726L ORDERING INFORMATION Ordering Number Normal Lead Free Package Packing L6726-D18-T L6726L-D18-T DIP-18 Tube L6726-S18-R L6726L-S18-R SOP-18 Tape Reel L6726-S18-T L6726L-S18-T SOP-18 Tube
L6726 LINEAR INTEGRATED CIRCUIT UNISONIC TECHNOLOGIES CO., LTD 2 of 13 www.unisonic.com.tw QW-R108-015,B PIN CONFIGURATION 109 DI MO MI 1 MI 2 RI DR RE 1 RE 2+L TO TI Mute GR DCS DCO DCC PIN DESCRIPTIONS Pin No. Pin Name Description 1 +L Output of the DC-regulator and trans mit amplifier. This pin is connec ted to the line through a polarity guard and diode bridge. 2 TO Output of the transmit amplif ier. This pin is connected through a resistor of 47 to 100 Ω to -L, which sets the DC-resistance of the circuit. The output has a low AC output impedance and the signal is used to drive a side tone balancing network. 3 TI Input of transmit amplifier. Input impedance 17k Ω±20% 4 +C The positive power supply terminal for most of the circuitry inside the UTC L6726 (about 1mA current consumption).The +C-PIN shall be connected to a decoupling capacitor of 47µF to 150µF 5 Mute When low, speech circuit is muted and the DTMF input is enabled. Maximum voltage (at mute) is 0.3V,current sink requirement of external driver is 50µA 6 GR Control input for the gain regulation circuitry. 7 DCS The sense input to the DC-supply. 8 DCO The output from the DC-supply.
9 DCC The control output from the DC-supply
10 DI The input for the DTMF -signal. Input impedance is 25kΩ±20%
11 MO Output of the microphone amplifier or DTMF-amplifier
12 MI 1
13 MI 2 Input to the microphone amplifier. Input impedance 1.7kΩ±20% 14 -L The negative power terminal, connected to the line though a polarity guard diode bridge 15 RI Input of receiver amplifier. Input impedance is approximately 38kΩ±20% 16 DR The control input for the receiver amplifier driving capability.
17 RE 1
18 RE 2 Receiver amplifier outputs. Output impedance is approximately 3Ω.
L6726 LINEAR INTEGRATED CIRCUIT UNISONIC TECHNOLOGIES CO., LTD 3 of 13 www.unisonic.com.tw QW-R108-015,B ABSOLUTE MAXIMUM RATINGS PARAMETER SYMBOL RATINGS UNIT Line Voltage, tp =2s V L 0~22 V Line Current, Continuous I L 0~130 mA Ambient Operating Temperature T OPR -40~+70 °C Storage Temperature T STG -55~+125 °C Note: Absolute maximum ratings are those values beyond which the device could be permanently damaged. Absolute maximum ratings are stress ratings only and functional device operation is not implied. ELECTRICAL CHARACTERISTICS (Ta=25Ċ unless otherwise specified) PARAMETER FIG. TEST CONDITIONS MIN TYP MAX UNIT Line Voltage 1 IL=15mA IL=100mA 3.3 3.7 4.1 15 V Transmitting Gain, Note 1 1 20·10log(V2/V3), 1kHz RL=0Ω RL=400Ω RL=900Ω~2.2kΩ 43.5 45.5 47.5 dB dB dB Transmitting Range Of Regulation 1 1kHz, R L=0 ~ 900 Ω 3 5 7 dB Transmitting Frequency Response 1 200Hz ~ 3.4kHz -1 1 dB Receiving Gain, Note 1 1 20·10log (V4/V1), 1kHz RL=0Ω RL=400Ω RL=900Ω~2.2kΩ -18.5 -16 -13.5 -16.5 -14 -11.5 -14.5 -12 -9.5 dB dB dB Receiving Range Of Regulation 1 1kHz, R L=0 ~ 900 Ω 3 5 7 dB Receiving frequency response 1 200Hz ~ 3.4kHz -1 1 dB Microphone Input Impedance Pin12,13 1 1kHz, note 3 1.7(//2.7) k Ω Transmitter Input Impedance Pin 3 1 1kHz 17 k Ω Transmitter Dynamic Output 1 200Hz~3.4kHz ≤2% distortion, IL=20~100mA 1.5 Vp Transmitter Max Output 1 200 Hz~3.4kHz IL=0-100mA,V3=0.1V 3 Vp Receiver Output Impedance 1 1kHz, note 3 3(+310) Ω Receiver Dynamic Output Note 2 1 200Hz~3.4kHz ≤2% distortion, IL=20~100mA 0.5 Vp Receiver Max Output 2 Measured with line rectifier 200 Hz~3.4kHz, IL=0~100mA, V1=0~50V 0.9 Vp Transmitter Output Noise 1 Ps of-weighting, Rel1 Vrms, RL=0 -75 dBpsof Receiver Output Noise 1 A-weighting, Rel 1Vrms, with cable 0~5km, φ=0.5mm, 0~3km, φ=0.3mm -85 dBA Mute Input Voltage at Mute (Active Low) 1 0.3 V D$-Supply Voltage 1 IL=10~100mA, IDC=0mA IL=10~100mA, IDC=2mA 2.35 2.2 V DC-Supply Current, Pin8 1 2 mA Dc-Output Pin8 Input Leakage Current (No Supply) 3 V DC=2.35V 0.1 µA DTMF Transmitting Gain 1 V M=0.3V 24.5 26.5 28.5 dB Notes:1. Adjustable to both higher and lower values with external components. 2. The dynamic output can be doubled, see applications information. 3. External resistor in the test set up.
1.Impedance to line and radio interference suppression. 2.Transmit gain and frequency response network. 3.Receive gain and frequency response network. 4.Side tone balance network. Figure 1. Test setup without rectifier bridge
Figure 3. Circuit with external components for test setup.
The gain of the transmitting and receiving amplifiers are continuously and euqually changed with the line length. under gain regulation below. The outputs of the transmitting and receiving amplifiers have internals limitations of the output amplitudes. in each of the transmitting and receiving amplifiers. The frequency response is except for that, flat for both amplifiers. for instance 600 Ωand against complex networks as 900 Ω in parallel with 30nF. To get a good CMRR the microphone input is balanced.
- Cut-off the microphone amplifier.
- Reduced gain in the receiving amplifier.
- Connection of the DTMF input.
Only resistive elements are used to set the receiving gain. A push-pull power stage in the receivin g amplifier gives a high output swing. solution requires only one capacitor while more capacitors can give better performance.
- For radio interference suppression and to give the correct return loss behavior.
- To set the gain and frequency response for transmitting.
- To set the gain and frequency response for receiving.
- To set the side-tone level
alters the DC characteristics of the speech circuit. Figure 4. Block interconnections
L6726 LINEAR INTEGRATED CIRCUIT UNISONIC TECHNOLOGIES CO., LTD 7 of 13 www.unisonic.com.tw QW-R108-015,B FUNCTIONAL DESCRIPTION(Cont.)
L6726 LINEAR INTEGRATED CIRCUIT UNISONIC TECHNOLOGIES CO., LTD 8 of 13 www.unisonic.com.tw QW-R108-015,B APPLICATION INFORMATION Refer to figure 6. Gain regulation (R1, R2): These resistors set the starting point for the gain-and side tone regulation. Input impedance pin 6 is about 5.5 k Ω±20%. Below are some typical values for R1 and R2, for some different supplies from telephone stations. Battery feed R1 R2 R6 No regulation Set for short line gain. All feedings 22k Ω 47~100 Ω Regulation: 48V, 2·200Ω 48V, 2·400Ω 36V, 2·500Ω 180kΩ 47Ω 75Ω 100Ω Impedance to line (R3, C1, C2): C1 in series with R3 and those in parallel with C2 give the impedance to the line from the set. C2 must normally be there for the interference too. The network is optimized with regard to the return loss. The time constant R3, C1 cannot be allowed to be too sma ll. If the time constant is to small, distortion at low frequencies may be generated. If R3 is changed this will change the DC-c haracteristic too, which set by the voltage at pin 4. The input current at pin 4 is about 1mA Microphone selection (M1, R16): The microphone can be either dynamic, magnet ic or electrets. See figures 12,14 and 15. The input impedance between pin 12 and 13 is about 1.7kΩ with typical variation ±20% Transmitting gain and frequency response (R4, R5, C3, C4): The network gives the amplification and frequency resp onse for the transmitter. R5 is used when a greater reduction of the gain is wanted. Input impedance at pin 3 is about 17 k Ω with typical variation ±20%.The sum of the resistors R4 and R5 must not be less than 35 k Ω because of DC-current to ground. Below is some simple variations of this network. (See figure 7). DC-characteristics (R6): Sets the DC-characteristic and take care of some of t he supplied power. The resistor have also function with the protection of the circuit, the transmitter, the gain regulation and side tone. Common values are 47 Ω to 100 Ω. Side tone level, receiving gain and frequency response.(R7,R8,R9,R10,R11,C5): The network sets the side tone balance. The network in the application is one of many possibilities. R10 and R11 balance together the signals that go two different ways from the transmitter output stage one from pin1 and the other from pin2. The balance network consist of R8, R9 and C5. The example is not optimized to any specified line, it is only given to show the principle. Fig8, 9 and 10 are examples of balance networks. Fig.10 is especially suited for lines with high current supply. The networks gives the gain and frequency response for the receiver. Input impedance at pin 15 is about 38 k Ω with a typical variation of ±20%.For different possibilities for the design of the network, see the network for the transmitter (R4, R5, C3) REC, R14: R14 generates the output impedance to the magnetic earphone (fig.11). If a dynamic earphone is used it should be placed between pin 17 and 18.See figure 16.
L6726 LINEAR INTEGRATED CIRCUIT UNISONIC TECHNOLOGIES CO., LTD 9 of 13 www.unisonic.com.tw QW-R108-015,B APPLICATION INFORMATION(Cont.) R15: This resistor is used to set the driving capability of the receiver output amp lifier. Common values are 0 Ω to 50 Ω. Setting it for low driving capability results in function at lower line current. Breaking up pin 16 will give lower power consumption and total mute of the receiver when muting the circuit. Disconnecting pin 15 will of cause also give total receiver mute. D1, D2, D3, D4, D5: Rectifier bridge and over voltage prot ector. The zener voltage at D5 should be as low as possible. Common values are between 12V~16V. R DC1, RDC2: Refer to figure 5. The pre-set output voltage of 2.35V can easily, if needed, be changed to another value by applying one or two resistor(R DC1,RDC2) in parallel with the internal resistors (each 15k Ω+/-20%).It is possible to get a rather high voltage and current from the DC-supply as long as the high current and voltage is available fr om the line. The DC voltage has to be filtered by a capacitor and this can, at high DC-voltage and low line cu rrent, interfere with the signal on the line and cause distortion. You can minimize the interference, with a resistor in series with the filter capacitor. The DC voltage will, of course, be more dependent of the DC-supp ly current. The DC-output pin has a very low input leak current, to allow stand-by feeding of the dialer. It is al so possible to use pin 9 to f eed microphones etc. that do not need stand-by feeding, without interferi ng with the stand-by feeding on pin 8. No te that a high current consumption by the external device will alter the DC characteristics of the speech circuit
L6726 LINEAR INTEGRATED CIRCUIT UNISONIC TECHNOLOGIES CO., LTD 10 of 13 www.unisonic.com.tw QW-R108-015,B APPLICATION INFORMATION(Cont.)
L6726 LINEAR INTEGRATED CIRCUIT UNISONIC TECHNOLOGIES CO., LTD 13 of 13 www.unisonic.com.tw QW-R108-015,B UTC assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all UTC products described or contained herein. UTC products are not designed for use in life support appliances, devices or systems where malfunction of these products can be reasonably expected to result in personal injury. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice.