L7554 AGERE | Alldatasheet
Document overview
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Technical content
Features
n Low active power (typical 165 mW during on-hook transmission) n Sleep state for low idle power (76 mW) n Quiet Tip/Ring polarity reversal n Supports meter pulse injection n Spare op amp for meter pulse filtering n –24 V to –72 V power supply operation n Distortion-free on-hook transmission n Convenient operating states: — Forward powerup — Polarity reversal powerup — Forward low-power scan — Polarity reversal low-power scan — Ground start — Disconnect (high impedance) n Adjustable supervision functions: — Off-hook detector with longitudinal rejection — Ground key detector — Ring trip detector n Independent, adjustable, dc and ac parameters: — dc feed resistance — Loop current limit — Termination impedance n Thermal protection
Description
This electronic subscriber loop interface circuit (SLIC) is optimized for low-power consumption while providing an extensive set of features. Quiet polarity reversal is possible because the ac path is uninterrupted during transition. The L7554 includes the ground start state and a summing node for meter pulse injection to 2.2 Vrms. A spare, uncommitted op amp is included for meter pulse filtering. The device is being offered in two versions, based upon maximum battery. The L7554AP is guaranteed to –60 V, and the L7554BP is guaranteed to –72 V. The device is available in a 44-pin PLCC package. It is built by using a 90 V complementary bipolar (CBIC) process.
2 Lucent Technologies Inc. Data Sheet March 1997L7554 Low-Power SLIC Table of Contents Content Page
Lucent Technologies Inc. 3 Data Sheet March 1997 L7554 Low-Power SLIC (continued) 12-2569 (C) Figure 1. Functional Diagram
Figure 2. Pin Diagram (PLCC Chip) Table 1. Pin Descriptions Current-Limit Program Input.
9 RCVP I
Receive ac Signal Input (Noninverting). differential voltage on Tip and Ring.
10 RCVN I
Receive ac Signal Input (Inverting). tial voltage on Tip and Ring.
11 TXI —
12 LCTH I
Loop Closure Threshold Input. Connect a resistor to DCOUT to set off-hook threshold. Regulated Negative dc Battery Voltage. Can be connected to an external regulator.
14 DCOUT O
value of the differential Tip/Ring current. Negative high-voltage power supply.
16 PR I/O
The output of the ring driver amplifier and input to loop sensing circuitry. Connect to loop through overvoltage protection.
18 CF2 —
F capacitor from this pin to AGND.
19 CF1 —
F capacitor from this pin to pin CF2.
38 FB2
20 VITR O
differential ac Tip/Ring current.
23 B0 I
B0, B1, and B2 determine the state of the SLIC. See Table 2.
24 AGND —
25 AGND —
26 DCR I
dc Resistance for Low Loop Currents. from DCOUT to ground with the tap at DCR.
27 BGND —
Ground return for the battery supply. 29 VTX O This output is a voltage that is directly proportional to the differential Tip/Ring current.
30 PT I/O
loop through overvoltage protection.
31 RTSN I
32 RTSP I
through a high-value resistor.
33 NRDET O
. When low, this logic output indicates that ringing is tripped.
34 NLC O
. When low, this logic output indicates an off-hook condition.
35 B2 I
. B0, B1, and B2 determine the state of the SLIC. See Table 2.
36 B1 I/O
. B0, B1, and B2 determine the state of the SLIC. See Table 2.
37 XMT O
. The output of the uncommitted operational amplifier.
38 SN I
or network to XMT sets the gain.
39 FB1 I
quiet polarity reversal. If not needed, the pin can be left open.
40 FB2 I
quiet polarity reversal. If not needed, the pin can be left open.
Table 2. Input State Coding Table 3. Supervision Coding periods can adversely affect device reliability. filter capacitor to cause a destructive overvoltage. PR. On-hook transmission is enabled. PT. On-hook transmission is enabled. Low-Power Scan, Reverse Battery. conserve power. Pin PR is positive with respect to PT. On-hook transmission is disabled. Low-Power Scan, Forward Battery. conserve power. Pin PT is positive with respect to PR. On-hook transmission is disabled.
5 V Power Supply V
Lucent Technologies Inc. 7 Data Sheet March 1997 L7554 Low-Power SLIC Recommended Operating Conditions
Electrical Characteristics
Minimum and maximum values are testing requirements. Typical values are characteristic of the device and are the result of engineering evaluations. Typical values are for information purposes only and are not part of the testing requirements. Minimum and maximum values apply across the entire temperature range (–40 °C to +85 °C) and the entire battery range unless otherwise specified. Typical is defined as 25 °C, V CC = 5.0 V, VBAT = –48 V, and ILIM = 40 mA. Positive currents flow into the device. Test circuit is Figure 4 unless noted. Table 4. Power Supply
- This parameter is not tested in production. It is guaranteed by design and device characterization.
Table 5. 2-Wire Port
- The longitudinal current is independent of dc loop current.
- Current-limit ILIM is programmed by a resistor, RPROG , from pin IPROG to DCOUT. ILIM is specified at the loop resistance where current limiting
begins (see Figure 25). Select RPROG (kW ) = 1.67 x ILIM (mA).
- IEEE is a registered trademark of The Institute of Electrical and Electronics Engineers, Inc.
- Longitudinal balance of circuit card will depend on loop series resistance matching (see Figures 23 and 24).
- This parameter is not tested in production. It is guaranteed by design and device characterization.
600 W ; not including protection)
50 Hz to 1 kHz
200 Hz to 4 kHz
Table 6. Analog Pin Characteristics
- Loop closure threshold is programmed by resistor RLCTH from pin LCTH to pin DCOUT.
- Ring ground threshold is programmed by resistor RICM2 from pin ICM to VCC .
Table 7. Uncommitted Op Amp Characteristics
Table 8. ac Feed Characteristics
- Set by external components. Any complex impedance R1 + R2 || C between 150 W and 1300 W can be synthesized.
- This parameter is not tested in production. It is guaranteed by design and device characterization.
- Return loss and transhybrid loss are functions of device gain accuracies and the external hybrid circuit. Guaranteed performance assumes
1% tolerance of external components.
200 Hz to 300 Hz
200 Hz to 500 Hz
500 Hz to 3400 Hz
Table 9. Logic Inputs and Outputs — Voltage, minimum 35 Vrms, maximum 100 Vrms. — Frequency, 17 Hz to 23 Hz. — The circuits in Figure 3 will not cause ringing trip. Figure 3. Ring Trip Circuits
14 Lucent Technologies Inc. Data Sheet March 1997L7554 Low-Power SLIC
Applications
12-2573 (C) Figure 11. Basic Loop Start Application Circuit Using T7513 Type Codec Figure 12. Ground Start Application Circuit
250 V PROT
14 DCOUT
12 LCTH
8 VCC
10 R GP
Table 10. Parts List for Loop Start and Ground Start Applications SLIC L7554 Subscriber loop interface circuit (SLIC). Protector 250 V Thyristor type Secondary protection. Ringing Relay L7581 Switches ringing signals. Codec T7513 First-generation codec. PT 20 W , Fusible Protection resistor. R PR 20 W , Fusible Protection resistor. BAT1 0.1 mF , 20%, 100 V V BAT filter capacitor. C F1 0.47 mF , 20%, 100 V With C F2, improves idle channel noise. C F2 0.1 mF , 20%, 100 V With C F1, improves idle channel noise. PROG 66.8 kW , 1%, 1/4 W Sets dc loop current limit. B2 0.1 mF , 20%, 100 V ac/dc separation capacitor. C GB 330 mF , 20%, 10 V Loop stability. R T1 86.6 kW , 1%, 1/4 W With R GP and RRCV , sets ac termination impedance. R RCV 48.7 kW , 1%, 1/4 W With R GP and RT1, sets receive gain. C GP 330 pF , 10 V, 20% Loop stability. R T2 18.7 kW , 1%, 1/4 W With R X, sets transmit gain in codec. R X 28.0 kW , 1%, 1/4 W With R T2, sets transmit gain in codec. R HB1 28.0 kW , 1%, 1/4 W Sets hybrid balance. LCTH 24.9 kW , 1%, 1/4 W Sets loop closure (off-hook) threshold. R TS1 402 W , 5%, 2 W Ringing source series resistor. C RTS1 0.022 mF , 20%, 5 V With R TSN , RTSP, forms second 2 Hz filter pole. C RTS2 0.27 mF , 20%, 100 V With R TS2 , forms first 2 Hz filter pole. R TSN 2 MW , 5%, 1/4 W With C RTS1 , RTSP, forms second 2 Hz filter pole. R TSP 2 MW , 5%, 1/4 W With C RTS1 , RTSN , forms second 2 Hz filter pole. ICM 0.47 mF , 20%, 10 V Provides 60 Hz filtering for ring ground detection. R GDET 100 kW , 20%, 1/4 W Digital output pull-up resistor. R ICM2 82.5 kW , 1%, 1/4 W Sets ring ground detection threshold.
to program these values are also shown. Table 11. 600 W Design Parameters
2020 Lucent Technologies Inc. |VBAT | = battery voltage magnitude. L = loop resistance, not including protection resistors. R P = protection resistor value. Rdc = SLIC internal dc feed resistance. The design begins by drawing the desired dc template. An example is shown in Figure 25. Figure 25. Loop Current vs. Loop Voltage Feed Resistance and Adjusting Overhead Voltage. the dc template has a high resistance (10 kW ). port of the SLIC can be programmed with pin DCR.
Figure 26. SLIC 2-Wire Output Stage between the Tip/Ring amplifiers and VSAT (4.0 V typ.). output series resistance of each internal amplifier. T/R (W ) is the ac loop impedance.
35 W protection resistors
undistorted 2.2 V metering signal. Figure 27. Equivalent Circuit for Adjusting the
2222 Lucent Technologies Inc. Figure 28. Equivalent Circuit for Adjusting the dc ting of the overhead voltage and the dc feed resistance. the two circuits as shown in Figure 29. Figure 29. Adjusting Both Overhead Voltage and dc feed resistance and overhead voltage together. tion of the external resistors. Figure 30. Off-Hook Detection Circuit
113 W 500 W R 1 25 kW||
application using unbalanced, battery-backed ringing. Figure 31. Ring Trip Equivalent Circuit and pole at 2 Hz was implemented to prevent false ring trip. The above equation is shown graphically in Figure 18.
2424 Lucent Technologies Inc. Data Sheet March 1997L7554 Low-Power SLIC Applications (continued) ac Design There are four key ac design parameters. Termination impedance is the impedance looking into the 2-wire port of the line card. It is set to match the impedance of the telephone loop in order to minimize echo return to the telephone set. Transmit gain is measured from the 2-wire port to the PCM highway, while receive gain is done from the PCM highway to the transmit port. Finally, the hybrid balance network cancels the unwanted amount of the receive signal that appears at the transmit port. At this point in the design, the codec needs to be select- ed. The discrete network between the SLIC and the codec can then be designed. The following is a brief codec feature and selection summary. First-Generation Codecs These perform the basic filtering, A/D (transmit), D/A (receive), and m-law/A-law companding. They all have an op amp in front of the A/D converter for transmit gain setting and hybrid balance (cancellation at the summing node). Depending on the type, some have differential analog input stages, differential analog output stages, and m-law/A-law selectability. This generation of codecs have the lowest cost. They are most suitable for appli- cations with fixed gains, termination impedance, and hybrid balance. Second-Generation Codecs This class of devices includes a microprocessor inter- face for software control of the gains and hybrid bal- ance. The hybrid balance is included in the device. ac programmability adds application flexibility and saves several passive components and also adds several I/O latches that are needed in the application. However, there is no transmit op amp, since the transmit gain and hybrid balance are set internally. Third-Generation Codecs This class of devices includes the gains, termination impedance, and hybrid balance—all under micropro- cessor control. Depending on the device, it may or may not include latches. Selection Criteria In the codec selection, increasing software control and flexibility are traded for device cost. To help decide, it may be useful to consider the following. Will the appli- cation require only one value for each gain and imped- ance? Will the board be used in different countries with different requirements? Will several versions of the board be built? If so, will one version of the board be most of the production volume? Does the application need only real termination impedance? Does the hybrid balance need to be adjusted in the field? In the following examples, use of a first-generation co- dec is shown. The equations for second- and third-gen- eration codecs are simply subsets of these. There are two examples: The first shows the simplest circuit, which uses a minimum number of discrete components to synthesize a real termination impedance. The second example shows the use of the uncommitted op amp to synthesize a complex termination. The design has been automated in a DOS-based program, available on re- quest.
2626 Lucent Technologies Inc. Figure 32. Use these to synthesize real termination
- The following expressions assume that the test net-
work is the same as the termination impedance.
1 R T1
1 R RCV
1 R T3
Lucent Technologies Inc. 27 Data Sheet March 1997 L7554 Low-Power SLIC Outline Diagram 44-Pin PLCC Controlling dimensions are in millimeters. 5-2506r7 (C) 4.57 MAX 1.27 TYP 0.53 MAX 0.10 SEATING PLANE
0.51 MIN
PIN #1 IDENTIFIER ZONE
16.66 MAX
17.65 MAX
16.66 MAX 17.65 MAX
March 1997L7554 Low-Power SLIC For additional information, contact your Microelectronics Group Account Manager or the following: INTERNET: http://www.lucent.com/micro U.S.A.: Microelectronics Group, Lucent Technologies Inc., 555 Union Boulevard, Room 30L-15P-BA, Allentown, PA 18103 1-800-372-2447, FAX 610-712-4106 (In CANADA: 1-800-553-2448, FAX 610-712-4106), e-mail docmaster@micro.lucent.com ASIA PACIFIC: Microelectronics Group, Lucent Technologies Singapore Pte. Ltd., 77 Science Park Drive, #03-18 Cintech III, Singapore 118256 Tel. (65) 778 8833, FAX (65) 777 7495 JAPAN: Microelectronics Group, Lucent Technologies Japan Ltd., 7-18, Higashi-Gotanda 2-chome, Shinagawa-ku, Tokyo 141, Japan Tel. (81) 3 5421 1600, FAX (81) 3 5421 1700 For data requests in Europe: MICROELECTRONICS GROUP DATALINE: Tel. (44) 1734 324 299, FAX (44) 1734 328 148 For technical inquiries in Europe: CENTRAL EUROPE: (49) 89 95086 0 (Munich), NORTHERN EUROPE: (44) 1344 865 900 (Bracknell UK), FRANCE: (33) 1 41 45 77 00 (Paris), SOUTHERN EUROPE: (39) 2 6601 1800 (Milan) or (34) 1 807 1700 (Madrid) Lucent Technologies Inc. reserves the right to make changes to the product(s) or information contained herein without notice. No liability is assumed as a result of their use or application. No rights under any patent accompany the sale of any such product(s) or information. Copyright © 1997 Lucent Technologies Inc. All Rights Reserved Printed in U.S.A. March 1997 DS97-202ALC (Replaces DS96-229LCAS) Printed On Recycled Paper
Ordering Information
*Devices on tape and reel must be ordered in 1000-piece increments. Device Part No. Description Package Comcode ATTL7554AP Low-Power SLIC, –60 V 44-Pin PLCC 107080921 ATTL7554AP–TR* Low-Power SLIC, –60 V 44-Pin PLCC (Tape and Reel) 107177172 ATTL7554BP Low-Power SLIC, –72 V 44-Pin PLCC 107548927 ATTL7554BP–TR* Low-Power SLIC, –72 V 44-Pin PLCC (Tape and Reel) 107548943