™
Quad Intelligent Subscriber Line Audio-processing Circuit
VE790 Series
APPLICATIONS
Voice over IP/DSL
—
Integrated Access Devices (IAD),
Smart Residential Gateways (SRG), Home Gateway/
Router
Cable Telephony
— NIU, Set-Top Box, Home Side
Le79Q2241/2242
ORDERING INFORMATION
Device
Le79Q2241VC
Le79Q2242JC
Package
64-pin TQFP
68-pin PLCC
Box, Cable Modem, Cable PC
Fiber
— Fiber in the Loop (FITL), Fiber to the
Home (FTTH)
Wireless Local Loop, Intelligent PBX
DLC-MUX
CO
DESCRIPTION
The Le79Q2241/2242 Quad Intelligent Subscriber Line Audio-
processing Circuit (ISLAC™) device, in combination with a
VE790 series ISLIC™ device, implements a fourchannel
universal telephone line interface. This enables the design of a
single, low-cost, high performance, fully software
programmable line interface for multiple country applications.
All AC, DC, and signaling parameters are fully programmable
via microprocessor or GCI interfaces. Additionally, the
Le79Q2241/2242 Quad ISLAC device has integrated self-test
and line-test capabilities to resolve faults to the line or line
circuit. The integrated test capability is crucial for remote
applications where dedicated test hardware is not cost
effective.
FEATURES
High performance digital signal processor provides
programmable control of all major line card functions
–
A-law/µ-law and linear codec
– Transmit and receive gain
– Two-wire AC impedance
– Transhybrid balance
– Equalization
DC loop feeding
– Smooth or abrupt polarity reversal
Loop supervision
– Off-hook debounce circuit
– Ground-key and ring-trip filters
Ringing generation and control
Line and circuit testing
Tone generation
Metering generation at 12 kHz and 16 kHz
– Envelope shaping and level control
Modem Tone Detection
Supports most available master clock frequencies
from 512 kHz to 8.192 MHz
–
–
RELATED LITERATURE
080248 Le79231 ISLIC™ Device Data Sheet
080249 Le79R241 ISLIC™ Device Data Sheet
080253 Le79R251 ISLIC™ Device Data Sheet
081054 Le79222 Dual ISLAC™ Device Data Sheet
080804 Le79R2xx/Le79Q224x Chip Set User’s Guide
–
–
–
–
–
–
BLOCK DIAGRAM
4
Selectable PCM/MPI or GCI digital interfaces
A
1
B
1
A
2
B
2
A
3
B
3
A
4
B
4
RC
Networks
and
Protection
7
VCCA
VCCD
DGND
1
DGND
2
ISLIC
LD
1
VREF
7
ISLIC
LD
2
ADGND
1
ADGND
2
4
I/O
1
- I/O
4
TSCA/G
TSCB
DRA/DD
DRB
General purpose I/O pins
+3.3-V DC operation
Exceeds LSSGR and ITU requirements
Supports external ringing with on-chip ring-trip circuit
–
Automatic or manual ring-trip modes
ISLIC
LD
3
P
1
-P
3
ISLIC
LD
4
DXB
Quad ISLAC
RREF
DXA/DU
DCLK/S0
PCLK/FS
MCLK
RSHB
BATH
RSLB
BATL
RSPB
BATP
CS/RST
DIO/S1
INT
FS/DCL
5
External
Ringing
Sense
Resistors
5
Supports CallerNumber Identification (CID)
Document ID#
080250 Date:
Nov 18, 2004
Rev:
J
Version: 1
Distribution:
Public Document
TABLE OF CONTENTS
Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
Related Literature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
Product Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Le79Q2241/2242 Device Internal Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Features of the Le79Q2241/2242 Chip Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Connection Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Pin Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Operating Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
DC Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Transmission and Signaling Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Transmit and Receive Paths. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Attenuation Distortion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Group Delay Distortion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Single Frequency Distortion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Gain Linearity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Total Distortion Including Quantizing Distortion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Overload Compression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Discrimination Against Out-of-Band Input Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Spurious Out-of-Band Signals at the Analog Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Switching Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Timing Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Microprocessor Interface Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
PCM Interface Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Master Clock Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
GCI Timing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
SLIC Device Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
Application Circuits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
Line card Parts List- Internal Ringing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
Line card Parts List - External Ringing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Physical Dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
68-Pin PLCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
64-Pin Thin Quad Flat Pack (TQFP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
Revision A to B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
Revision B to C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
Revision C to D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
Revision D to E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
Revision E to F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
Revision F to G . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
Revision G to H . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
Revision H to I1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
Revision I1 to J1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
2
Le79Q2241/2242 VE790 Series Data Sheet
PRODUCT DESCRIPTION
The VE790 series voice chip sets integrate all functions of the subscriber line for four subscriber lines. One or more of two chip
types are used to implement the line card; a VE790 series SLIC device and a Le79Q2241/2242 Quad ISLAC device. These
provide the following basic functions:
The VE790 series SLIC device: A high voltage, bipolar IC that drives the subscriber line, maintains longitudinal balance and
senses line conditions.
2. The Le79Q2241/2242 Quad ISLAC™ device: A low voltage CMOS IC that provides conversion and DSP functions for all four
channels.
Complete schematics of line cards using the Le79Q2241/2242 Quad ISLAC device for internal and external ringing are shown
in
Application Circuits,
on page 29.
The VE790 series SLIC device uses reliable, bipolar technology to provide the power necessary to drive a wide variety of
subscriber lines. It can be programmed by the Quad ISLAC device to operate in eight different modes that control power
consumption and signaling. This enables it to have full control over the subscriber loop. The VE790 series SLIC device is
designed to be used exclusively with the Le79Q2241/2242 Quad ISLAC device as part of a multiple-line chip set.
The VE790 series SLIC device implements a linear loop-current feeding method with the enhancement of intelligent thermal
management in a controlled manner. This limits the amount of power dissipated on the VE790 series SLIC chip by dissipating
excess power in external resistors.
Each Le79Q2241/2242 Quad ISLAC device contains high-performance codec circuits that provide A/D and D/A conversion for
voice (codec), DC-feed and supervision signals for four subscriber channels. The Le79Q2241/2242 Quad ISLAC device contains
a DSP core that handles signaling, DC-feed, supervision and line diagnostics for all four channels.
The DSP core selectively interfaces with three types of backplanes:
•
Standard PCM/MPI
•
Standard GCI
•
Modified GCI with a single analog line per GCI channel
The Le79Q2241/2242 Quad ISLAC device provides a complete software configurable solution to the BORSCHT functions as well
as complete programmable control over subscriber line DC-feed characteristics, such as current limit and feed resistance. In
addition, these chip sets provide system level solutions for the loop supervisory functions and metering. In total, they provide a
programmable solution that can satisfy worldwide line card requirements by software configuration.
Software programmed filter coefficients, DC-feed data and supervision data are easily calculated with the WinSLAC software.
This PC software is provided free of charge and allows the designer to enter a description of system requirements. WinSLAC
then computes the necessary coefficients and plots the predicted system results.
The VE790 series SLIC device interface unit inside the Le79Q2241/2242 Quad ISLAC device processes information regarding
the line voltages, loop currents and battery voltage levels. These inputs allow the Le79Q2241/2242 Quad ISLAC device to place
several key VE790 series SLIC device performance parameters under software control.
The main functions that can be observed and/or controlled through the Le79Q2241/2242 Quad ISLAC device backplane interface
are:
•
DC-feed characteristics
•
Ground-key detection
•
Off-hook detection
•
Metering signal
•
Longitudinal operating point
•
Subscriber line voltage and currents
•
Ring-trip detection
•
Abrupt and smooth reversal
•
Subscriber line matching
•
Ringing generation
•
Sophisticated line and circuit tests
To accomplish these functions, the VE790 series SLIC device collects the following information and feeds it, in analog form, to
the Le79Q2241/2242 Quad ISLAC device:
•
•
The metallic (I
MT
) and longitudinal (I
LG
) loop currents
The AC (VTX) and DC (VSAB) loop voltages
1.
Le79Q2241/2242 VE790 Series Data Sheet
3
The outputs supplied by the Le79Q2241/2242 Quad ISLAC device to the VE790 series SLIC device are then:
•
•
•
•
•
•
A voltage (VHL
i
*) that provides control for the following high-level VE790 series SLIC device outputs:
DC loop current
Internal ringing signal
12- or 16-kHz metering signal
A low-level voltage proportional to the voice signal (VOUT
i
)
A voltage that controls longitudinal offset for test purposes (VLB
i
)
The Le79Q2241/2242 Quad ISLAC device performs the codec and filter functions associated with the four-wire section of the
subscriber line circuitry in a digital switch. These functions involve converting an analog voice signal into digital PCM samples
and converting digital PCM samples back into an analog signal. During conversion, digital filters are used to band-limit the voice
signals.
The user-programmable filters set the receive and transmit gain, perform the transhybrid balancing function, permit adjustment
of the two-wire termination impedance and provide frequency attenuation adjustment (equalization) of the receive and transmit
paths. Transhybrid balancing is also included. All programmable digital filter coefficients can be calculated using WinSLAC™
software. The PCM codes can be either 16-bit linear two’s-complement or 8-bit companded A-law or µ-law.
Besides the codec functions, the Le79Q2241/2242 Quad ISLAC device provides all the sensing, feedback, and clocking
necessary to completely control VE790 series SLIC device functions with programmable parameters. System-level parameters
under programmable control include active loop current limits, feed resistance, and feed mode voltages.
The Le79Q2241/2242 Quad ISLAC device supplies complete mode control to the VE790 series SLIC device using the control
bus and (P1-P3) tri-level load signal (LD
i
).
The Le79Q2241/2242 Quad ISLAC device provides extensive loop supervision capability including off-hook, ring-trip and ground-
key detection. Detection thresholds for these functions are programmable. A programmable debounce timer is available that
eliminates false detection due to contact bounce.
For subscriber line diagnostics, AC and DC line conditions can be monitored using built in test tools. Measured parameters can
be compared to programmed threshold levels to set a pass/fail bit. The user can choose to send the actual PCM measurement
data directly to a higher level processor by way of the voice channel. Both longitudinal and metallic resistance and capacitance
can be measured, which allows leakage resistance, line capacitance, and telephones to be identified.
Note:
"i" denotes channel number
4
Le79Q2241/2242 VE790 Series Data Sheet
Le79Q2241/2242 Device Internal Block Diagram
IREF VREF
VHL
1
VLB
1
VOUT
1
VIN
1
VSAB
1
VIMT
1
VILG
1
XSB
1
Ch 1
Converter
Block
Clock and
Reference
Circuits
PCM
and
GCI
Interface
and
Time Slot
Assigner
MCLK
FS/DCL
PCLK/FS
DXA/DU
DRA/DD
TSCA/G
DXB
DRB
TSCB
DCLK/S0
Ch 2
(as Ch 1)
DIO/S1
CS/RST
INT
I/O
1
I/O
2
I/O
3
I/O
4
LD
1
LD
2
Ch 4
(as Ch 1)
ISLIC
Control
Logic
LD
3
LD
4
P
1
P
2
P
3
XSC
SHB
SLB
SPB
Digital
Signal
Processor
GCI Control
Logic and
Microprocessor
Interface
Ch 3
(as Ch 1)
Common
External
Sense
Inputs
Le79Q2241/2242 VE790 Series Data Sheet
5
Embedded System
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