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L7556 Datasheet(PDF) 2 Page - Agere Systems |
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L7556 Datasheet(HTML) 2 Page - Agere Systems |
2 / 28 page 2 Lucent Technologies Inc. Data Sheet January 2000 with Battery Switch L7556, L7557 Low-Power SLICs Table of Contents Contents Page Features ..................................................................... 1 Description .................................................................. 1 Pin Information ............................................................ 4 Functional Description ................................................. 6 Absolute Maximum Ratings ........................................ 6 Recommended Operating Conditions ......................... 7 Electrical Characteristics ............................................. 7 Ring Trip Requirements ......................................... 11 Test Configurations .................................................. 12 Applications .............................................................. 14 Design Considerations ........................................... 16 Characteristic Curves............................................. 17 dc Applications ....................................................... 20 Battery Feed......................................................... 20 Switching the Battery............................................ 20 Overhead Voltage ............................................... 21 Adjusting Overhead Voltage ................................ 21 Adjusting dc Feed Resistance.............................. 22 Loop Range.......................................................... 22 Off-Hook Detection .............................................. 22 Ring Trip Detection.............................................. 23 Ring Ground Detection........................................ 23 ac Design ............................................................... 24 First-Generation Codecs ..................................... 24 Second-Generation Codecs ................................ 24 Third-Generation Codecs .................................... 24 Selection Criteria ................................................. 24 PCB Layout Information ............................................ 26 Outline Diagram......................................................... 27 32-Pin PLCC ........................................................... 27 Ordering Information.................................................. 28 Tables Page Table 1. Pin Descriptions ............................................ 4 Table 2. Input State Coding ........................................ 6 Table 3. Supervision Coding ....................................... 6 Table 4. Power Supply ................................................ 7 Table 5. 2-Wire Port .................................................... 8 Table 6. Analog Pin Characteristics ............................ 9 Table 7. Uncommitted Op Amp Characteristics .......... 9 Table 8. ac Feed Characteristics .............................. 10 Table 9. Logic Inputs and Outputs ............................ 11 Table 10. Parts List for Loop Start and Ground Start Applications ...................................... 15 Table 11. 600 Ω Design Parameters .........................16 Figures Page Figure 1. Functional Diagram ..................................... 3 Figure 2. Pin Diagram (PLCC Chip) ........................... 4 Figure 3. Ring Trip Circuits ....................................... 11 Figure 4. Basic Test Circuit ....................................... 12 Figure 5. Longitudinal Balance ................................. 12 Figure 6. Longitudinal PSRR .................................... 13 Figure 7. RFI Rejection ............................................. 13 Figure 8. Longitudinal Impedance ............................ 13 Figure 9. Metallic PSRR ........................................... 13 Figure 10. ac Gains ..................................................13 Figure 11. Basic Loop Start Application Circuit Using T7504 Type Codec ........................14 Figure 12. Ring Ground Detection Circuit ................. 14 Figure 13. Receive Gain and Hybrid Balance vs. Frequency ............................................... 17 Figure 14. Transmit Gain and Return Loss vs. Frequency ............................................... 17 Figure 15. Typical VCC Power Supply Rejection ....... 17 Figure 16. Typical VBAT Power Supply Rejection ................................................. 17 Figure 17. Loop Closure Program Resistor Selection ..................................................18 Figure 18. Ring Ground Detection Programming .....18 Figure 19. Loop Current vs. Loop Voltage ................ 18 Figure 20. Loop Current vs. Loop Resistance .......... 18 Figure 21. Typical SLIC Power Dissipation vs. Loop Resistance ...................................... 19 Figure 22. Power Derating ........................................ 19 Figure 23. Longitudinal Balance Resistor Mismatch Requirements .......................................... 19 Figure 24. Longitudinal Balance vs. Protection Resistor Mismatch ................................... 19 Figure 25. Loop Current vs. Loop Voltage ................ 20 Figure 26. SLIC 2-Wire Output Stage ....................... 21 Figure 27. Equivalent Circuit for Adjusting the Over- head Voltage ........................................... 21 Figure 28. Equivalent Circuit for Adjusting the dc Feed Resistance ...................................... 22 Figure 29. Adjusting Both Overhead Voltage and dc Feed Resistance .....................................22 Figure 30. Off-Hook Detection Circuit Applications ............................................. 22 Figure 31. Ring Trip Equivalent Circuit and Equivalent Application ............................. 23 Figure 32. ac Equivalent Circuit Not Including Spare Op Amp ................................................... 25 Figure 33. ac Equivalent Circuit Including Spare Op Amp ................................................... 25 |
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