DS3153N ,Single/Dual/Triple/Quad DS3/E3/STS-1 LIUsFEATURES The DS3151 (single), DS3152 (dual), DS3153 Single, Dual, Triple, or Quad Integrated (tr ..
DS3153N+ ,Single/Dual/Triple/Quad DS3/E3/STS-1 LIUsBlock Diagram ......9 Figure 5-1. Status Register Logic .16 Figure 6-1. Receiver Jitter Tolerance . ..
DS3154 ,Single/Dual/Triple/Quad DS3/E3/STS-1 LIUsFeatures continued on page 5. RXN DATAOR STS-1 AND DATA Dallas Semiconductor ORDERING INFORMATIO ..
DS3154 ,Single/Dual/Triple/Quad DS3/E3/STS-1 LIUsFEATURES The DS3151 (single), DS3152 (dual), DS3153 Single, Dual, Triple, or Quad Integrated (trip ..
DS3154+ ,Single/Dual/Triple/Quad DS3/E3/STS-1 LIUsELECTRICAL CHARACTERISTICS ........37 14. PIN ASSIGNMENTS......46 15. PACKAGE INFORMATION....59 16. ..
DS3154A2 ,Single/Dual/Triple/Quad DS3/E3/STS-1 LIUsPIN DESCRIPTIONS .....10 5. REGISTER DESCRIPTIONS..15 6. RECEIVER...22 7. TRANSMITTER ....25 8. DIA ..
EA2-12 ,COMPACT AND LIGHTWEIGHTAPPLICATIONSElectronic switching systems, PBX, key telephone systems, automatic test equipment and ..
EA2-12NU ,COMPACT AND LIGHTWEIGHTFEATURESª Low power consumptionª Compact and light weightª 2 form c contact arrangementª Low magnet ..
EA2-12S ,COMPACT AND LIGHTWEIGHTFEATURESª Low power consumptionª Compact and light weightª 2 form c contact arrangementª Low magnet ..
EA2-12TNU ,COMPACT AND LIGHTWEIGHTAPPLICATIONSElectronic switching systems, PBX, key telephone systems, automatic test equipment and ..
EA2-4.5NU ,COMPACT AND LIGHTWEIGHTAPPLICATIONSElectronic switching systems, PBX, key telephone systems, automatic test equipment and ..
EA2-4.5T ,COMPACT AND LIGHTWEIGHTDATA SHEETMINIATURE SIGNAL RELAYEA2 SERIESCOMPACT AND LIGHTWEIGHTDESCRIPTIONThe EA2 series has red ..
DS3153N-DS3154N
Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
GENERAL DESCRIPTION The DS3151 (single), DS3152 (dual), DS3153
(triple), and DS3154 (quad) line interface units (LIUs)
perform the functions necessary for interfacing at the physical layer to DS3, E3, or STS-1 lines. Each LIU
has independent receive and transmit paths and a built-in jitter attenuator.
APPLICATIONS SONET/SDH and PDH Multiplexers Digital Cross-Connects
Access Concentrators ATM and Frame Relay Equipment
Routers PBXs
DSLAMs CSUs/DSUs
FUNCTIONAL DIAGRAM
FEATURES Single, Dual, Triple, or Quad Integrated
Transmitter, Receiver, and Jitter Attenuators for DS3, E3, and STS-1 Each Port Independently Configurable Perform Receive Clock/Data Recovery and
Transmit Waveshaping Hardware or CPU Bus Configuration Options Jitter Attenuators can be Placed in Either the Receive or Transmit Paths Interface to 75� Coaxial Cable at Lengths Up to
380m (DS3), 440m (E3), or 360m (STS-1) Use 1:2 Transformers on Tx and Rx Require Minimal External Components Local and Remote Loopbacks Low-Power 3.3V Operation (5V Tolerant I/O) Industrial Temperature Range:
-40°C to +85�C Small Package: 144-Pin, 13mm x 13mm
Thermally Enhanced CSBGA IEEE 1149.1 JTAG Support
Features continued on page 5.
ORDERING INFORMATION
DS3151/DS3152/DS3153/DS3154
Single/Dual/Triple/Quad
DS3/E3/STS-1 LIUs
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
TABLE OF CONTENTS
1. DETAILED DESCRIPTION.................................................................................................5
2. APPLICATIONS.................................................................................................................7
3. HARDWARE MODE AND CPU BUS MODE......................................................................8
4. PIN DESCRIPTIONS........................................................................................................10
5. REGISTER DESCRIPTIONS............................................................................................15
6. RECEIVER........................................................................................................................22
7. TRANSMITTER................................................................................................................25
8. DIAGNOSTICS.................................................................................................................28
9. JITTER ATTENUATOR....................................................................................................29
10. RESET LOGIC..................................................................................................................30
11. TRANSFORMERS............................................................................................................31
12. JTAG TEST ACCESS PORT AND BOUNDARY SCAN..................................................32
13. ELECTRICAL CHARACTERISTICS................................................................................37
14. PIN ASSIGNMENTS.........................................................................................................46
15. PACKAGE INFORMATION..............................................................................................59
16. THERMAL INFORMATION..............................................................................................60
17. REVISION HISTORY........................................................................................................60 DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
LIST OF FIGURES Figure 1-1. External Connections............................................................................................................7
Figure 2-1. 4-Port Unchannelized DS3/E3 Card......................................................................................7
Figure 3-1. Hardware Mode Block Diagram.............................................................................................8
Figure 3-2. CPU Bus Mode Block Diagram..............................................................................................9
Figure 5-1. Status Register Logic..........................................................................................................16
Figure 6-1. Receiver Jitter Tolerance.....................................................................................................24
Figure 7-1. E3 Waveform Template.......................................................................................................27
Figure 7-2. DS3 AIS Structure...............................................................................................................28
Figure 8-1. PRBS Output with Normal RCLK Operation........................................................................29
Figure 8-2. PRBS Output with Inverted RCLK Operation.......................................................................29
Figure 9-1. Jitter Attenuation/Jitter Transfer...........................................................................................30
Figure 12-1. JTAG Block Diagram.........................................................................................................32
Figure 12-2. JTAG TAP Controller State Machine.................................................................................33
Figure 13-1. Transmitter Framer Interface Timing Diagram...................................................................38
Figure 13-2. Receiver Framer Interface Timing Diagram.......................................................................39
Figure 13-3. CPU Bus Timing Diagram (Nonmultiplexed)......................................................................41
Figure 13-4. CPU Bus AC Timing Diagram (Multiplexed).......................................................................43
Figure 13-5. JTAG Timing Diagram.......................................................................................................45
Figure 14-1. DS3151 Hardware Mode Pin Assignment..........................................................................51
Figure 14-2. DS3151 CPU Bus Mode Pin Assignment..........................................................................52
Figure 14-3. DS3152 Hardware Mode Pin Assignment..........................................................................53
Figure 14-4. DS3152 CPU Bus Mode Pin Assignment..........................................................................54
Figure 14-5. DS3153 Hardware Mode Pin Assignment..........................................................................55
Figure 14-6. DS3153 CPU Bus Mode Pin Assignment..........................................................................56
Figure 14-7. DS3154 Hardware Mode Pin Assignment..........................................................................57
Figure 14-8. DS3154 CPU Bus Mode Pin Assignment..........................................................................58
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
LIST OF TABLES Table 1-A. Applicable Telecommunications Standards............................................................................6
Table 4-A. Active I/O PinsHardware and CPU Bus Modes.................................................................10
Table 4-B. Transmitter Pin Descriptions................................................................................................11
Table 4-C. Receiver Pin Descriptions....................................................................................................12
Table 4-D. Global Pin Descriptions........................................................................................................13
Table 4-E. JTAG and Test Pin Descriptions..........................................................................................14
Table 4-F. Transmitter Data Select Options...........................................................................................14
Table 4-G. Receiver PRBS Pattern Select Options................................................................................14
Table 5-A. Register Map........................................................................................................................15
Table 7-A. DS3 Waveform Template.....................................................................................................26
Table 7-B. DS3 Waveform Test Parameters and Limits.........................................................................26
Table 7-C. STS-1 Waveform Template..................................................................................................26
Table 7-D. STS-1 Waveform Test Parameters and Limits.....................................................................27
Table 7-E. E3 Waveform Test Parameters and Limits...........................................................................27
Table 11-A. Transformer Characteristics...............................................................................................31
Table 11-B. Recommended Transformers.............................................................................................31
Table 12-A. JTAG Instruction Codes.....................................................................................................35
Table 12-B. JTAG ID Code....................................................................................................................35
Table 13-A. Recommended DC Operating Conditions...........................................................................37
Table 13-B. DC Characteristics.............................................................................................................37
Table 13-C. Framer Interface Timing.....................................................................................................38
Table 13-D. Receiver Input CharacteristicsDS3 and STS-1 Modes....................................................39
Table 13-E. Receiver Input CharacteristicsE3 Mode..........................................................................39
Table 13-F. Transmitter Output CharacteristicsDS3 and STS-1 Modes.............................................40
Table 13-G. Transmitter Output CharacteristicsE3 Mode...................................................................40
Table 13-H. CPU Bus Timing................................................................................................................40
Table 13-I. JTAG Interface Timing.........................................................................................................45
Table 14-A. Pin Assignments Sorted by Signal Name...........................................................................46
Table 14-B. Pin Assignments Sorted by Pin Number.............................................................................48
Table 16-A. Thermal Properties, Natural Convection.............................................................................60
Table 16-B. Theta-JA (�JA) vs. Airflow....................................................................................................60
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
FEATURES (continued)
Receiver AGC/equalizer block handles from 0 to 15dB of cable loss Loss-of-lock (LOL) PLL status indication Interfaces directly to a DSX monitor signal (~20dB flat loss) using built-in preamp Digital and analog loss-of-signal (LOS) detectors (ANSI T1.231 and ITU G.775) Optional B3ZS/HDB3 decoder Line-code violation output pin and counter Binary or bipolar framer interface On-board 215 - 1 and 223 - 1 PRBS detector Clock inversion for glueless interfacing Tri-state clock and data outputs support protection switching applications Per-channel power-down control
Transmitter Binary or bipolar framer interface Gapped clock capable up to 51.84MHz Wide 50 �20% transmit clock duty cycle Clock inversion for glueless interfacing Optional B3ZS/HDB3 encoder On-board 215 - 1 and 223 - 1 PRBS generator Complete DS3 AIS generator (ANSI T1.107) Unframed all-ones generator (E3 AIS) Line build-out (LBO) control Tri-state line driver outputs support protection switching applications Per-channel power-down control Output driver monitor
1. DETAILED DESCRIPTION The DS3151 (single), DS3152 (dual), DS3153 (triple), and DS3154 (quad) LIUs perform the functions necessary
for interfacing at the physical layer to DS3, E3, or STS-1 lines. Each LIU has independent receive and transmit paths and a built-in jitter attenuator. The receiver performs clock and data recovery from a B3ZS- or HDB3-coded
alternate mark inversion (AMI) signal and monitors for loss of the incoming signal. The receiver optionally performs B3ZS/HDB3 decoding and outputs the recovered data in either binary or bipolar format. The transmitter accepts
data in either binary or bipolar format, optionally performs B3ZS/HDB3 encoding, and drives standard pulse-shape
waveforms onto 75� coaxial cable. The jitter attenuator can be mapped into the receiver data path, mapped into the transmitter data path, or be disabled. The DS315x LIUs conform to the telecommunications standards listed in
Table 1-A. Figure 1-1 shows the external components required for proper operation.
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
Table 1-A. Applicable Telecommunications Standards DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
Figure 1-1. External Connections 2. APPLICATIONS
Figure 2-1. 4-Port Unchannelized DS3/E3 Card
Shorthand Notations. The notation DS315x throughout this data sheet refers to either the DS3151, DS3152, DS3153, or DS3154. This data sheet is the specification for all four parts. The LIUs on the DS315x are identical.
For brevity, this document uses the pin name and register name shorthand NAMEn, where n stands in place of the LIU port number. For example, on the DS3154 quad LIU, TCLKn is shorthand notation for pins TCLK1, TCLK2,
TCLK3, and TCLK4 on LIU ports 1, 2, 3, and 4, respectively. This document also uses generic pin and register names such as TCLK (without a number suffix) when describing LIU operation. When working with a specific LIU
on the DS315x devices, generic names like TCLK should be converted to actual pin names, such as TCLK1.
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
3. HARDWARE MODE AND CPU BUS MODE The DS315x can operate in either hardware mode or CPU bus mode. In hardware mode, pulling configuration input
pins high or low does all configuration, and all status information is reported on status output pins. Internal registers are not accessible in hardware mode. The device is configured for hardware mode when the HW pin is wired high
(HW = 1).
In CPU bus mode, most of the configuration and status pins used in hardware mode are reassigned to be address, data, and control lines that provide a glueless interface to an 8-bit microprocessor bus. Through the CPU bus, an
external processor can access a set of internal registers. Setting configuration register bits high or low can do configuration, and status information can be read from status register bits. Events indicated by status register bits
can also activate the interrupt output pin (INT), if configured to do so by a set of interrupt-enable bits. A few
configuration and status pins are active in hardware mode and CPU bus mode to support specialized applications, such as protection switching. The device is configured for CPU bus mode when the HW pin is wired low (HW = 0).
With the exception of the HW pin, configuration and status pins available in hardware mode have corresponding
register bits in the CPU bus mode. The hardware mode pins and the CPU bus mode register bits have identical names and functions, with the exception that all register bits are active high. For example, LOS is indicated by the
receiver on the RLOS pin (active low) in hardware mode and the RLOS register bit (active high) in CPU bus mode.
The few configuration input pins that are active in CPU bus mode also have corresponding register bits. In these cases, the actual configuration is the logical OR of pin assertion and register bit assertion. For example, the
transmitter output driver is tri-stated if the TTS pin is asserted (i.e., low) or the TTS register bit is asserted (high).
Figure 3-1 and Figure 3-2 show block diagrams of the DS315x in hardware mode and in CPU bus mode. Table 4-A lists the pins that are active in each mode.
Figure 3-1. Hardware Mode Block Diagram
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
Figure 3-2. CPU Bus Mode Block Diagram
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
4. PIN DESCRIPTIONS
Table 4-A. Active I/O PinsHardware and CPU Bus Modes Note: In CPU bus mode, status/control pins are replaced by register bits. See Register Map in Section 5. For pin names of the form PINn,
n = LIU# = 1, 2, 3, or 4. PIN1 is on LIU 1, PIN2 is on LIU 2, etc.
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
Table 4-B. Transmitter Pin Descriptions
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
Table 4-C. Receiver Pin Descriptions
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
Table 4-D. Global Pin Descriptions
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs Table 4-E. JTAG and Test Pin Descriptions Note 1: Pin type I = input pin. Pin type O = output pin. Pin type P = power-supply pin.
Note 2: Pin type O3 is an output that can be tri-stated.
Note 3: Pin type IPU is an input with an internal 10k� pullup.
Note 4: For pin names of the form PINn, n = LIU# = 1, 2, 3, or 4. PIN1 is on LIU 1, PIN2 is on LIU 2, etc.
Note 5: Section 14 shows hardware mode and CPU bus mode pin assignments. Table 4-F. Transmitter Data Select Options
Note 1: This coding of the TDSA, TDSB, E3M, and STS bits allows AIS generation to be enabled by holding TDSA = 0 and changing TDSB
from 0 to 1. The type of DS3 AIS signal is selected by the STS bit with E3M = 0.
Note 2: If E3M and/or STS are changed when {TDSA,TDSB} � 00, TDSA and TDSB must both be cleared to 0. After they are cleared, TDSA
and TDSB can be configured to transmit a pattern in the new operating mode.
Table 4-G. Receiver PRBS Pattern Select Options
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
5. REGISTER DESCRIPTIONS
When the DS315x is configured in CPU bus mode (HW = 0), the registers shown in Table 5-A are accessible
through the CPU bus interface. All registers for the LIU ports are forced to their default values during an internal
power-on reset or when the RST pin is driven low. Setting an LIUs RST bit high forces all registers for that LIU to their default values. All register bits marked must be written 0 and ignored when read. The TEST registers
must be left at their reset value of 00h for normal operation.
On the DS3153, only registers for LIUs 1, 2, and 3 are available. Writes into LIU 4 address space are ignored. Reads from LIU 4 address space return all zeros. On the DS3152, address line A5 is not present, limiting the
address space to the LIU 1 and 2 registers. On the DS3151, address lines A5 and A4 are not present, limiting the address space to the LIU 1 registers. Table 5-A. Register Map Note 1: Underlined bits are read-only; all other bits are read-write.
Note 2: The registers are named REGn, where n = the LIU number (1, 2, 3, or 4).
Note 3: The bit names are the same for each LIU register set.
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
Status Register Description
The status registers have two types of status bits. Real-time status bitslocated in the SRn registersindicate the
state of a signal at the time it was read. Latched status bitslocated in the SRLn registersare set when a signal changes state (low-to-high, high-to-low, or both, depending on the bit) and cleared when written with a logic 1
value. After clearing, latched status bits remain cleared until the signal changes state again. Interrupt-enable bitslocated in the SRIEn registerscontrol whether or not the INT pin is driven low when latched register bits are set. Figure 5-1. Status Register Logic Register Name: GCRn
Register Description: Global Configuration Register Register Address: 00h, 10h, 20h, 30h Bit 7 6 5 4 3 2 1 0
Name E3M
Default
Bit 7: E3 Mode Enable (E3M) 0 = DS3 operation
1 = E3 or STS-1 operation
Bit 6: STS-1 Mode Enable (STS) When E3M = 1,
0 = E3 operation 1 = STS-1 operation
When E3M = 0, STS selects the DS3 AIS pattern (Table 4-F).
Bits 5, 4: Local Loopback, Remote Loopback Select (LLB, RLB) 00 = no loopback
01 = remote loopback 10 = analog local loopback
11 = digital local loopback
Bits 3, 2: Transmitter Data Select (TDSA, TDSB). See Table 4-F for details.
Bit 0: Reset (RST). When this bit is high, the digital logic of the LIU is held in reset and all registers for that LIU
(except the RST bit) are forced to their default values. RST is cleared to 0 at power-up and when the RST pin is activated.
0 = normal operation 1 = reset LIU
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
Register Name: TCRn
Register Description: Transmitter Configuration Register Register Address: 01h, 11h, 21h, 31h Bit 7 6 5 4 3 2 1 0
Name
Default
Bit 6: Transmitter Binary Interface Enable (TBIN) 0 = Transmitter framer interface is bipolar on the TPOS and TNEG pins. The B3ZS/HDB3 encoder is
disabled. 1 = Transmitter framer interface is binary on the TDAT pin. The B3ZS/HDB3 encoder is enabled. Bit 5: Transmitter Clock Invert (TCINV)
0 = TPOS/TDAT and TNEG are sampled on the rising edge of TCLK. 1 = TPOS/TDAT and TNEG are sampled on the falling edge of TCLK. Bit 4: Transmitter Jitter Attenuator Enable (TJA)
0 = Remove jitter attenuator from the transmitter path. 1 = Insert jitter attenuator into the transmitter path. Bit 3: Transmitter Power-Down Enable (TPD)
0 = enable the transmitter 1 = power-down the transmitter (output driver tri-stated) Bit 2: Transmitter Tri-State Enable (TTS). This bit is set to 1 on reset, which tri-states the transmitter TXP and
TXN pins. The transmitter circuitry is left powered up in this mode. The TTS input pin is inverted and logically ORed
with this bit. 0 = enable the transmitter output driver
1 = tri-state the transmitter output driver
Bit 1: Transmitter Line Build-Out (TLBO). TLBO indicates cable length for waveform shaping in DS3 and STS-1 modes. TLBO is ignored in E3 mode.
0 = cable length � 225ft
1 = cable length < 225ft
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
Register Name: RCRn
Register Description: Receiver Configuration Register Register Address: 02h, 12h, 22h, 32h Bit 7 6 5 4 3 2 1 0
Name ITU
Default
Bit 7: ITU CV Mode (ITU). This bit controls what types of bipolar violations (BPVs) are flagged as code violations on the RLCV pin and counted in the RCV register. It also controls whether or not excessive zero (EXZ) events are
flagged and counted. An EXZ event is the occurrence of a third consecutive zero (DS3 or STS-1 modes) or fourth consecutive zero (E3 mode) in a sequence of zeros.
0 = In all three modes (DS3, E3, and STS-1) BPVs that are not part of a valid codeword are flagged and counted. EXZ events are also flagged and counted.
1 = In DS3 and STS-1 modes, BPVs that are not part of valid codewords are flagged and counted. In E3 mode, BPVs that are the same polarity as the last BPV are flagged and counted. EXZ events are not
flagged and counted in any mode.
Bit 6: Receiver Binary Interface Enable (RBIN) 0 = Receiver framer interface is bipolar on the RPOS and RNEG pins. The B3ZS/HDB3 decoder is
disabled. 1 = Receiver framer interface is binary on the RDAT pin with the RLCV pin indicating line-code violations.
The B3ZS/HDB3 encoder is enabled.
Bit 5: Receiver Clock Invert (RCINV) 0 = RPOS/RDAT and RNEG/RLCV are sampled on the rising edge of RCLK.
1 = RPOS/RDAT and RNEG/RLCV are sampled on the falling edge of RCLK.
Bit 4: Receiver Jitter Attenuator Enable (RJA). (Note that TJA = 1 takes precedence over RJA = 1.) 0 = remove jitter attenuator from the receiver path
1 = insert jitter attenuator into the receiver path
Bit 3: Receiver Power-Down Enable (RPD) 0 = enable the receiver
1 = power-down the receiver (RPOS/RDAT, RNEG/RLCV, and RCLK tri-stated)
Bit 2: Receiver Tri-State Enable (RTS). This signal is set to 1 on reset, which tri-states the receiver RPOS/RDAT,
RNEG/RLCV, and RCLK pins. The receiver is left powered up in this mode. The RTS pin is inverted and logically ORed with this bit.
0 = enable the receiver outputs 1 = tri-state the receiver outputs (RPOS/RDAT, RNEG/RLCV, and RCLK) Bit 1: Receiver Monitor Preamp Enable (RMON)
0 = disable the monitor preamp 1 = enable the monitor preamp
Bit 0: Receive Code-Violation Counter Update (RCVUD). When this control bit transitions from low to high, the
RCVLn and RCVHn registers are loaded with the current code-violation count, and the internal code-violation counter is cleared.
0�1 = Update RCV registers and clear internal code-violation counter
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
Register Name: SRn
Register Description: Status Register Register Address: 03h, 13h, 23h, 33h Bit 7 6 5 4 3 2 1 0
Name
Default
Bit 5: Transmitter Driver Monitor (TDM). This read-only status bit indicates the current state of the transmit driver monitor.
0 = the transmitter is operating normally 1 = the transmitter has a fault condition Bit 4: PRBS Detector Output (PRBS). This read-only status bit indicates the current state of the receivers PRBS
detector. See Table 4-G for the expected PRBS pattern. 0 = in sync with expected pattern
1 = out of sync, expected pattern not detected
Bit 1: Receiver Loss of Lock (RLOL). This read-only status bit indicates the current state of the receiver clock recovery PLL.
0 = the receiver PLL is locked onto the incoming signal 1 = the receiver PLL is not locked onto the incoming signal Bit 0: Receiver Loss of Signal (RLOS). This read-only status bit indicates the current state of the receiver loss-of-
signal detector. 0 = signal present
1 = loss of signal
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
Register Name: SRLn
Register Description: Status Register Latched Register Address: 04h, 14h, 24h, 34h Bit 7 6 5 4 3 2 1 0
Name
Default
Bit 5: Transmitter Driver Monitor Latched (TDML). This latched status bit is set to one when the TDM status bit changes state (low to high or high to low). TDML is cleared when the host processor writes a one to it and is not set
again until TDM changes state again. When TDML is set, it can cause a hardware interrupt to occur if the TDMIE interrupt-enable bit is set to one. The interrupt is cleared when TDML is cleared or TDMIE is set to zero. Bit 4: PRBS Detector Output Latched (PRBSL). This latched status bit is set to one when the PRBS status bit
changes state (low to high or high to low). PRBSL is cleared when the host processor writes a one to it and is not set again until PRBS changes state again. When PRBSL is set, it can cause a hardware interrupt to occur if the
PRBSIE interrupt-enable bit is set to one. The interrupt is cleared when PRBSL is cleared or PRBSIE is set to zero.
Bit 3: PRBS Detector Bit Error Latched (PBERL). This latched status bit is set to one when the PRBS detector is in sync and a bit error has been detected. PBERL is cleared when the host processor writes a one to it and is not
set again until another bit error is detected. When PBERL is set, it can cause a hardware interrupt to occur if the PBERIE interrupt-enable bit is set to one. The interrupt is cleared when PBERL is cleared or PBERIE is set to zero. Bit 2: Receiver Code Violation Latched (RCVL). This latched status bit is set to one when the RCV status bit
goes high. RCVL is cleared when the host processor writes a one to it and is not set again until RCV goes high again. When RCVL is set, it can cause a hardware interrupt to occur if the RCVIE interrupt-enable bit is set to one.
The interrupt is cleared when RCVL is cleared or RCVIE is set to zero.
Bit 1: Receiver Loss-of-Clock Lock Latched (RLOLL). This latched status bit is set to one when the RLOL status bit changes state (low to high or high to low). RLOLL is cleared when the host processor writes a one to it and is
not set again until RLOL changes state again. When RLOLL is set, it can cause a hardware interrupt to occur if the RLOLIE interrupt-enable bit is set to one. The interrupt is cleared when RLOLL is cleared or RLOLIE is set to zero. Bit 0: Receiver Loss-of-Signal Latched (RLOSL). This latched status bit is set to one when the RLOS status bit
changes state (low to high or high to low). RLOSL is cleared when the host processor writes a one to it and is not set again until RLOS changes state again. When RLOSL is set, it can cause a hardware interrupt to occur if the
RLOSIE interrupt-enable bit is set to one. The interrupt is cleared when RLOSL is cleared or RLOSIE is set to zero.
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
Register Name: SRIEn
Register Description: Status Register Interrupt Enable Register Address: 05h, 15h, 25h, 35h Bit 7 6 5 4 3 2 1 0
Name
Default
Bit 5: Transmitter Driver Monitor Interrupt Enable (TDMIE) 0 = mask TDML interrupt
1 = enable TDML interrupt
Bit 4: PRBS Detector Interrupt Enable (PRBSIE) 0 = mask PRBSL interrupt
1 = enable PRBSL interrupt
Bit 3: PRBS Detector Bit-Error Interrupt Enable (PBERIE) 0 = mask PBERL interrupt
1 = enable PBERL interrupt
Bit 2: Receiver Line-Code Violation Interrupt Enable (RCVIE) 0 = mask RCVL interrupt
1 = enable RCVL interrupt
Bit 1: Receiver Loss-of-Clock Lock Interrupt Enable (RLOLIE) 0 = mask RLOLL interrupt
1 = enable RLOLL interrupt
Bit 0: Receiver Loss-of-Signal Interrupt Enable (RLOSIE) 0 = mask RLOSL interrupt
1 = enable RLOSL interrupt Register Name: RCVLn
Register Description: Receiver Code-Violation Count Register (Low Byte) Register Address: 06h, 16h, 26h, 36h Bit 7 6 5 4 3 2 1 0
Name
Default
Register Name: RCVHn Register Description: Receiver Code-Violation Count Register (High Byte)
Register Address: 07h, 17h, 27h, 37h Bit 7 6 5 4 3 2 1 0
Name
Default Bits 15 to 0: Receiver Code-Violation Counter Register (RCV[15:0]). The RCV registers form a 16-bit register
for reading the line-code violation counter value. The registers are updated with the line-code violation counter value when the RCVUD control bit is toggled low to high. After the RCV registers are updated, the line-code
violation counter is cleared. The counter operates in two modes, depending on the setting of the ITU bit in the RCR register. See the RCR register description for details about the ITU control bit.
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
6. RECEIVER
Interfacing to the Line. The receiver can be transformer-coupled or capacitor-coupled to the line. Typically, the
receiver interfaces to the incoming coaxial cable (75�) through a 1:2 step-up transformer. Figure 1-1 shows the arrangement of the transformer and other recommended interface components. Table 11-A specifies the required characteristics of the transformer. The receiver expects the incoming signal to be in B3ZS- or HDB3-coded AMI
format.
Optional Preamp. The receiver can be used in monitoring applications, which typically have series resistors with a resistive loss of approximately 20dB. When the RMON input pin is high, the receiver compensates for this resistive
loss by applying approximately 14dB of flat gain to the incoming signal before sending the signal to the AGC/equalizer block where additional flat gain is applied as needed. Automatic Gain Control (AGC) and Adaptive Equalizer. The AGC circuitry applies flat (frequency independent)
gain to the incoming signal to compensate for flat losses in the transmission channel and variations in transmission power. Since the incoming signal also experiences frequency-dependent losses as it passes through the coaxial
cable, the adaptive equalizer circuitry applies frequency-dependent gain to offset line losses and restore the signal. The AGC/equalizer circuitry automatically adapts to coaxial cable losses from 0 to 15dB, which translates into 0 to
380 meters (DS3), 0 to 440 meters (E3), or 0 to 360 meters (STS-1) of coaxial cable (AT&T 734A or equivalent). The AGC and the equalizer work simultaneously but independently to supply a signal of nominal amplitude and
pulse shape to the clock and data recovery block. The AGC/equalizer block automatically handles direct (0 meters) monitoring of the transmitter output signal. Clock and Data Recovery (CDR). The CDR block takes the amplified, equalized signal from the AGC/equalizer
block and produces separate clock, positive data, and negative data signals. The CDR requires a master clock. If the signal on the appropriate MCLK pin is toggling, the LIU selects the MCLK signal as its master clock. If the
appropriate MCLK pin is wired high, the LIU uses the signal on the TCLK pin as the master clock. The appropriate MCLK is selected based on the settings of the E3M and STS mode pins or register bits. The receiver locks onto the incoming signal using a clock recovery PLL. The status of the PLL lock is indicated in
the RLOL status bit. The RLOL bit is set when the difference between recovered clock frequency and MCLK frequency is greater than 7900ppm and cleared when the difference is less than 7700ppm. A change of state of the
RLOL status bit can cause an interrupt on the INT pin if enabled to do so by the RLOLIE interrupt-enable bit. Note
that if MCLK is not present, or MCLK is high and TCLK is not present, RLOL is not set.
Loss-of-Signal (LOS) Detector. The receiver contains analog and digital LOS detectors. The analog LOS detector resides in the AGC/equalizer block. If the incoming signal level is less than a signal level approximately 24dB below
nominal, analog LOS (ALOS) is declared. The ALOS signal cannot be directly examined, but when ALOS occurs the AGC/equalizer mutes the recovered data, forcing all zeros out of the data recovery circuitry and causing digital
LOS (DLOS), which is indicated by the RLOS pin and the RLOS status bit. ALOS clears when the incoming signal
level is greater than or equal to a signal level approximately 18dB below nominal.
The digital LOS detector declares DLOS when it detects 175 �75 consecutive zeros in the recovered data stream. When DLOS occurs, the receiver asserts the RLOS pin (hardware mode) or the RLOS status bit (CPU bus mode).
DLOS is cleared when there are no EXZ occurrences over a span of 175 �75 clock periods. An EXZ occurrence is defined as three or more consecutive zeros in the DS3 and STS-1 modes and four or more consecutive zeros in
the E3 mode. The RLOS pin goes inactive (high) when the DLOS condition is cleared. In CPU bus mode, a change
of the RLOS status bit can cause an interrupt on the INT pin if enabled to do so by the RLOSIE interrupt-enable bit.
The requirements of ANSI T1.231 and ITU-T G.775 for DS3 LOS defects are met by the DLOS detector, which
asserts RLOS when it counts 175 �75 consecutive zeros coming out of the CDR block and clears RLOS when it
counts 175 �75 consecutive pulse intervals without excessive zero occurrences. The requirements of ITU-T G.775 for E3 LOS defects are met by a combination of the ALOS detector and the
DLOS detector, as follows:
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
For E3 RLOS Assertion:
1) The ALOS detector in the AGC/equalizer block detects that the incoming signal is less than or equal to a signal level approximately 24dB below nominal, and mutes the data coming out of the clock and data recovery block.
(24dB below nominal in the tolerance range of G.775, where LOS may or may not be declared.)
2) The DLOS detector counts 175 �75 consecutive zeros coming out of the CDR block and asserts RLOS. (175
�75 meets the 10 � N � 255 pulse-interval duration requirement of G.775.)
For E3 RLOS Clear: 1) The ALOS detector in the AGC/equalizer block detects that the incoming signal is greater than or equal to a
signal level approximately 18dB below nominal, and enables data to come out of the CDR block. (18dB is in the tolerance range of G.775, where LOS may or may not be declared.)
2) The DLOS detector counts 175 �75 consecutive pulse intervals without EXZ occurrences and deasserts
RLOS. (175 �75 meets the 10 � N � 255 pulse-interval duration requirement of G.775.)
The DLOS detector supports the requirements of ANSI T1.231 for STS-1 LOS defects. At STS-1 rates, the time
required for the DLOS detector to count 175 �75 consecutive zeros falls in the range of 2.3� T� 100�s required by
ANSI T1.231 for declaring an LOS defect. Although the time required for the DLOS detector to count 175 �75
consecutive pulse intervals with no excessive zeros is less than the 125�s250�s period required by ANSI T1.231 for clearing an LOS defect, a period of this length where LOS is inactive can easily be timed in software.
During LOS, the RCLK output pin is derived from the LIUs master clock. The ALOS detector has a longer time constant than the DLOS detector. Thus, when the incoming signal is lost, the DLOS detector activates first
(asserting the RLOS pin or bit), followed by the ALOS detector. When a signal is restored, the DLOS detector does not get a valid signal that it can qualify for no EXZ occurrences until the ALOS detector has seen the signal rise
above a signal level approximately 18dB below nominal.
Framer Interface Format and the B3ZS/HDB3 Decoder. The recovered data can be output in either binary or
bipolar format. To select the bipolar interface format, pull the RBIN pin low (hardware mode) or clear the RBIN configuration bit (CPU bus mode). In bipolar format, the B3ZS/HDB3 decoder is disabled and the recovered data is
buffered and output on the RPOS and RNEG outputs. Received positive-polarity pulses are indicated by RPOS = 1, while negative-polarity pulses are indicated by RNEG = 1. In bipolar interface format, the receiver simply passes
on the received data and does not check it for BPV or EXZ occurrences.
To select the binary interface format, pull the RBIN pin high (hardware mode) or set the RBIN configuration bit (CPU bus mode). In binary format, the B3ZS/HBD3 decoder is enabled, and the recovered data is decoded and output as a binary value on the RDAT pin. Code violations are flagged on the RLCV pin. In the discussion that
follows, a valid pulse that conforms to the AMI rule is denoted as B. A BPV pulse that violates the AMI rule is denoted as V.
In DS3 and STS-1 modes, B3ZS decoding is performed. RLCV is asserted during any RCLK cycle where the data on RDAT causes ones of the following code violations:
��Hardware mode or ITU bit set to 0 A BPV immediately preceded by a valid pulse (B, V). A BPV with the same polarity as the last BPV. The third zero in an EXZ occurrence.
��ITU bit set to 1 A BPV immediately preceded by a valid pulse (B, V). A BPV with the same polarity as the last BPV.
In E3 mode, HDB3 decoding is performed. RLCV is asserted during any RCLK cycle where the data on RDAT
causes one of the following code violations:
��Hardware mode or ITU bit set to 0 A BPV immediately preceded by a valid pulse (B, V) or by a valid pulse and a zero (B, 0, V). A BPV with the same polarity as the last BPV. The fourth zero in an EXZ occurrence (only in hardware mode or when ITU = 0).
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
��ITU bit set to 1 A BPV with the same polarity as the last BPV.
When RLCV is asserted to flag a BPV, the RDAT pin outputs a one. The state bit that tracks the polarity of the last BPV is toggled on every BPV, whether part of a valid B3ZS/HDB3 codeword or not.
To support a glueless interface to a variety of neighboring components, the polarity of RCLK can be inverted. Normally, data is output on the RPOS/RDAT and RNEG/RLCV pins on the falling edge of RCLK. To output data on
these pins on the rising edge of RCLK, pull the RCINV pin high (hardware mode) or set the RCINV configuration bit (CPU bus mode).
The RCLK, RPOS/RDAT, and RNEG/RLCV pins can be tri-stated to support protection switching and redundant-LIU applications. This tri-stating capability supports system configurations where two or more LIUs are wire-ORed
together and a system processor selects one to be active. To tri-state RCLK, RPOS/RDAT, and RNEG/RLCV,
assert the RTS pin or the RTS configuration bit.
Receive Line-Code Violation Counter. The line-code violation counter is always enabled regardless of the
settings of the RBIN pin or the RBIN configuration bit. The receiver has an internal 16-bit saturating counter and a 16-bit latch, which the CPU can read as registers RCVH and RCVL. The value of the internal counter is latched into
the RCVH/RCVL register and cleared when the receive code-violation counter update bit, RCVUD, is changed from a zero to a one. The RCVUD bit must be cleared back to a zero before a new update can occur. If there is an LCV
increment pulse and an update pulse in the same clock period, the counter is preset to a one rather than cleared so that the LCV is not missed. The counter is incremented when the RLCV pin flags a code violation as described in the Framer Interface Format and the B3ZS/HDB3 Decoder section. The counter saturates at 65,535 (0FFFFh)
and does not roll over.
Receiver Power-Down. To minimize power consumption when the receiver is not being used, assert the RPD
configuration bit (CPU bus mode). When the receiver is powered down, the RCLK, RPOS/RDAT, and RNEG/RLCV pins are tri-stated. In addition, the RXP and RXN pins become high impedance.
Receiver Jitter Tolerance. The receiver exceeds the input jitter tolerance requirements of all applicable
telecommunication standards in Table 1-A. See Figure 6-1.
Figure 6-1. Receiver Jitter Tolerance
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
7. TRANSMITTER
Transmit Clock. The clock applied at the TCLK input clocks in data on the TPOS/TDAT and TNEG pins. If the jitter
attenuator is not enabled in the transmit path, the signal on TCLK is the transmit line clock and must be
transmission quality (i.e., �20ppm frequency accuracy and low jitter). If the jitter attenuator is enabled in the transmit path, the signal on TCLK can be jittery and/or periodically gapped (not exceeding 8UI), but must still have
an average frequency within �20ppm of the nominal line rate. When enabled in the transmit path, the jitter attenuator generates the transmit line clock from the signal applied on the appropriate MCLK pin. The signal on the
MCLK pin must, therefore, be a transmission-quality clock (�20ppm frequency accuracy and low jitter). The polarity of TCLK can be inverted to support glueless interfacing to a variety of neighboring components.
Normally data is sampled on the TPOS/TDAT and TNEG pins on the rising edge of TCLK. To sample data on the falling edge of TCLK, pull the TCINV pin high (hardware mode) or set the TCINV configuration bit (CPU bus mode). Framer Interface Format and the B3ZS/HDB3 Encoder. Data to be transmitted can be input in either binary or
bipolar format. To select the binary interface format, pull the TBIN pin high (hardware mode) or set the TBIN configuration bit (CPU bus mode). In binary format, the B3ZS/HBD3 encoder is enabled, and the data to be
transmitted is sampled on the TDAT pin. The TNEG pin is ignored in binary interface mode and should be wired low. In DS3 and STS-1 modes, the B3ZS/HDB3 encoder operates in the B3ZS mode. In E3 mode the encoder
operates in HDB3 mode.
To select the bipolar interface format, pull the TBIN pin low (hardware mode) or clear the TBIN configuration bit (CPU bus mode). In bipolar format, the B3ZS/HDB3 encoder is disabled and the data to be transmitted is sampled
on the TPOS and TNEG pins. Positive-polarity pulses are indicated by TPOS = 1, while negative-polarity pulses are indicated by TNEG = 1. Pattern Generation. The transmitter can generate several patterns internally, including unframed all ones (E3
AIS), 100100
, and DS3 AIS. See Figure 7-2 for the structure of the DS3 AIS signal. The TDSA and TDSB input pins (hardware mode) or the TDSA and TDSB control bits (CPU bus mode) are used to select these patterns.
Table 4-F indicates the possible selections.
Waveshaping, Line Build-Out, Line Driver. The waveshaping block converts the transmit clock, positive data, and negative data signals into a single AMI signal with the waveshape required for interfacing to DS3/E3/STS-1
lines. Table 7-A through Table 7-E and Figure 7-1 show the waveform template specifications and test parameters.
Because DS3 and STS-1 signals must meet the waveform templates at the cross-connect through any cable length from 0 to 450ft, the waveshaping circuitry includes a selectable LBO feature. For cable lengths of 225ft or greater,
the TLBO pin (hardware mode) or the TLBO configuration bit (CPU bus mode) should be low. When TLBO is low, output pulses are driven onto the coaxial cable without any preattenuation. For cable lengths less than 225ft, TLBO
should be high to enable the LBO circuitry. When TLBO is high, pulses are preattenuated by the LBO circuitry before being driven onto the coaxial cable. The LBO circuitry provides attenuation that mimics the attenuation of
225ft of coaxial cable.
The transmitter line driver can be disabled and the TXP and TXN outputs tri-stated by asserting the TTS input or
the TTS configuration bit. Powering down the transmitter through the TPD configuration bit (CPU bus mode) also tri-states the TXP and TXN outputs.
Interfacing to the Line. The transmitter interfaces to the outgoing DS3/E3/STS-1 coaxial cable (75�) through a
2:1 step-down transformer connected to the TXP and TXN pins. Figure 1-1 shows the arrangement of the transformer and other recommended interface components. Table 11-A specifies the required characteristics of the
transformer.
Transmit Driver Monitor. If the transmit driver monitor detects a faulty transmitter, it activates the TDM output
(hardware mode or CPU bus mode) or sets the TDM status bit and optionally activates the INT output (CPU bus mode). When the transmitter is tri-stated, the transmit driver monitor is also disabled. The transmitter is declared to
be faulty when the transmitter outputs see a load of less than ~25�.
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
Transmitter Power-Down. To minimize power consumption when the transmitter is not being used, assert the
TPD configuration bit (CPU bus mode only). When the transmitter is powered down, the TXP and TXN pins are put in a high-impedance state and the transmit amplifiers are powered down. Transmitter Jitter Generation (Intrinsic). The transmitter meets the jitter generation requirements of all
applicable standards, with or without the jitter attenuator enabled.
Transmitter Jitter Transfer. Without the jitter attenuator enabled in the transmit side, the transmitter passes jitter through unchanged. With the jitter attenuator enabled in the transmit side, the transmitter meets the jitter transfer
requirements of all applicable telecommunication standards in Table 1-A. See Figure 9-1. Table 7-A. DS3 Waveform Template
Governing Specifications: ANSI T1.102 and Bellcore GR-499. Table 7-B. DS3 Waveform Test Parameters and Limits Table 7-C. STS-1 Waveform Template Governing Specifications: Bellcore GR-253 and Bellcore GR-499 and ANSI T1.102.
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
Table 7-D. STS-1 Waveform Test Parameters and Limits Table 7-E. E3 Waveform Test Parameters and Limits
Figure 7-1. E3 Waveform Template
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
Figure 7-2. DS3 AIS Structure
M1 Subframe
M2 Subframe
M3 Subframe
M4 Subframe
M5 Subframe M6 Subframe
M7 Subframe
Note 1: X1 is transmitted first.
Note 2: The 84 info bits contain the repetitive sequence 1010
, where the first 1 in the sequence immediately follows each X, P, F, C, or M bit.
8. DIAGNOSTICS
PRBS Generator and Detector. Each LIU has built-in pseudorandom bit sequence (PRBS) generator and detector circuitry for physical layer testing. The device generates and detects unframed 215 - 1 (DS3 or STS-1) or 223 - 1
PRBS, according to the ITU O.151 specification. To transmit a PRBS pattern, pull the TDSA and TDSB pins high (hardware mode) or set configuration bits TDSA and TDSB (CPU bus mode). As Table 4-F shows, the PRBS
generator automatically generates 215 - 1 for DS3 and STS-1 modes and 223 - 1 for E3 mode.
The PRBS detector, which is always enabled (Table 4-G), reports its status through the PRBS output pin (hardware and CPU bus modes) or through the PRBS and PBER status bits (CPU bus mode). When the PRBS detector is out
of synchronization, the PRBS pin is forced high. When the detector syncs to an incoming PRBS pattern, the PRBS pin is driven low, then pulses high, synchronous with RCLK, for each bit error detected. See Figure 8-1 and Figure
8-2 for details. In CPU bus mode, the PRBS status bit is set to one when the detector is out of synchronization and set to zero when the detector syncs to an incoming PRBS pattern. A change of state of the PRBS bit can cause an
interrupt on the INT pin if the PRBSIE interrupt-enable bit is set to one. A pattern bit error can also cause an
interrupt if the PBERIE interrupt-enable bit is set to one. The PRBS detector also declares sync in the presence of
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
Loopbacks. Each LIU has three internal loopbacks. See Figure 3-1 and Figure 3-2. The LLB and RLB pins
(hardware mode) or LLB and RLB control bits (CPU bus mode) enable these loopbacks. When LLB = RLB = 0, loopbacks are disabled. Setting RLB = 1 with LLB = 0 enables remote loopback, which loops recovered clock and
data back through the LIU transmitter. During remote loopback, recovered clock and data are output on RCLK, RPOS/RDAT, and RNEG/RLCV, but the TPOS/TDAT and TNEG pins are ignored. Setting LLB = 1 with RLB = 0
enables analog local loopback, which loops the outgoing transmit signal back to the receivers analog front end. Setting LLB = RLB = 1 enables digital local loopback, which loops digital transmit clock and data back to the
receivers digital circuitry, including the LOS detector, the B3ZS/HDB3 decoder, and the PRBS detector. When either of the local loopbacks is enabled, the transmit signal is output normally on TXP/TXN, but the received signal
on RXP/RXN is ignored. Figure 8-1. PRBS Output with Normal RCLK Operation
Figure 8-2. PRBS Output with Inverted RCLK Operation
9. JITTER ATTENUATOR
Each LIU contains an on-board jitter attenuator that can be placed in the receive path or the transmit path or can
be disabled. The TJA and RJA pins (hardware mode) or the TJA and RJA control bits (CPU bus mode) specify how the jitter attenuator is used. Setting TJA = RJA = 0 disables the jitter attenuator. To use the jitter attenuator in the
receive path, set RJA = 1 (with TJA = 0). To use it in the transmit path, set TJA = 1. Figure 9-1 shows the minimum jitter attenuation for the device when the jitter attenuator is enabled. Figure 9-1 also shows the receive jitter transfer
when the jitter attenuator is disabled.
The jitter attenuator consists of a narrowband PLL to retime the selected clock, a 16 x 2-bit FIFO to buffer the associated data while the clock is being retimed, and logic to prevent FIFO over/underflow in the presence of very
large jitter amplitudes.
The jitter attenuator requires a transmission-quality master clock (i.e., �20ppm frequency accuracy and low jitter).
When enabled in the receive path, the JA can obtain its master clock from the appropriate MCLK pin or the TCLK pin. If the signal on the MCLK pin is toggling, the JA uses the signal on the MCLK pin as its master clock. If the
DS3151/DS3152/DS3153/DS3154 Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs
the JA must take its master clock from the MCLK pin. The clock and data recovery block also uses the selected
master clock.
The JA has a loop bandwidth of master_clock / 2,058,874 (see corner frequencies in Figure 9-1). The JA attenuates jitter at frequencies higher than the loop bandwidth, while allowing jitter (and wander) at lower
frequencies to pass through relatively unaffected.
Figure 9-1. Jitter Attenuation/Jitter Transfer
10. RESET LOGIC
There are four sources for reset: an internal power-on reset (POR) circuit, the reset pin RST, the JTAG reset pin
JTRST, and the RST bit in each LIUs global configuration register (GCR). The chip is divided into three zones for
reset: the digital logic, the analog circuits, and the JTAG logic. The digital logic includes the status and control registers, the B3ZS/HDB3 encoder and decoder, the PRBS generator and detector, and the LOS detect logic. The
analog circuits include clock and data recovery, jitter attenuator, and transmit waveform generation. The JTAG logic consists of the common boundary scan controller and the boundary scan cells at each pin.
The POR circuit resets the digital logic, analog circuits, and JTAG logic zones. The RST pin resets the digital logic
and the analog circuits but not the JTAG logic. The JTRST pin resets only the JTAG logic. Each LIUs RST register bit resets the digital logic for that LIU, including resetting the LIUs registers to the default state (except for the RST
bit).
The POR signal and RST pin require an active master clock source for the LIU to properly reset.
