LXT362 Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications Datasheet The LXT362 is a fully integrated, combination transceiver for T1 ISDN Primary Rate Interface and general T1 long and short haul applications. It operates over 22 AWG twisted-pair cables from 0 to 6 kft and offers Line Build Outs and pulse equalization settings for all T1 Line Interface Unit (LIU) applications. LXT362 provides both a serial port for microprocessor control (Host mode) as well as standalone operation (Hardware mode). The device incorporates advanced crystal-less digital jitter attenuation in either the transmit or receive data path starting at 3 Hz. B8ZS encoding/decoding and unipolar or bipolar data I/O are selectable. Loss of signal monitoring and a variety of diagnostic loopback modes can also be selected. Applications ■ ■ ■ ISDN Primary Rate Interface (ISDN PRI) CSU/NTU interface to T1 Service Wireless Base Station interface ■ ■ ■ T1 LAN/WAN bridge/routers T1 Mux; Channel Banks Digital Loop Carrier - Subscriber Carrier Systems Product Features ■ ■ ■ ■ ■ ■ Fully integrated transceiver for Long or Short-Haul T1 interfaces — Crystal-less digital jitter attenuation — Select either transmit or receive path No crystal or high speed external clock required Meets or exceeds specifications in ANSI T1.102, T1.403 and T1.408; and AT&T Pub 62411 Supports 100 Ω (T1 twisted-pair) applications Selectable receiver sensitivity – fully restores the received signal after transmission through a cable with attenuation of either 0 to 26 dB, or 0 to 36 dB @ 772 kHz Five Pulse Equalization Settings for T1 short-haul applications ■ ■ ■ ■ ■ ■ ■ ■ Four Line Build-Outs for T1 long-haul applications from 0 dB to -22.5 dB Transmit/receive performance monitors with Driver Fail Monitor Open and Loss of Signal outputs Selectable unipolar or bipolar data I/O and B8ZS encoding/decoding Line attenuation indication output in 2.9 dB steps QRSS generator/detector for testing or monitoring Local, remote, and analog loopback, plus in-band network loopback code generation and detection Multiple register serial interface for microprocessor control Available in 28-pin PLCC, 44-pin PQFP, and 44-pin LQFP packages As of January 15, 2001, this document replaces the Level One document Order Number: 249033-001 known as LXT362 — Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications. January 2001 Information in this document is provided in connection with Intel® products. No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted by this document. Except as provided in Intel’s Terms and Conditions of Sale for such products, Intel assumes no liability whatsoever, and Intel disclaims any express or implied warranty, relating to sale and/or use of Intel products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. Intel products are not intended for use in medical, life saving, or life sustaining applications. Intel may make changes to specifications and product descriptions at any time, without notice. Designers must not rely on the absence or characteristics of any features or instructions marked "reserved" or "undefined." Intel reserves these for future definition and shall have no responsibility whatsoever for conflicts or incompatibilities arising from future changes to them. The LXT362 may contain design defects or errors known as errata which may cause the product to deviate from published specifications. Current characterized errata are available on request. Contact your local Intel sales office or your distributor to obtain the latest specifications and before placing your product order. Copies of documents which have an ordering number and are referenced in this document, or other Intel literature may be obtained by calling 1-800548-4725 or by visiting Intel’s website at http://www.intel.com. Copyright © Intel Corporation, 2001 *Third-party brands and names are the property of their respective owners. Datasheet Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications — LXT362 Contents 1.0 Pin Assignments and Signal Descriptions ...................................................... 8 1.1 2.0 Mode Dependent Signals ...................................................................................... 9 Functional Description...........................................................................................14 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Initialization..........................................................................................................14 2.1.1 Reset Operation .....................................................................................14 Transmitter ..........................................................................................................14 2.2.1 Transmit Digital Data Interface...............................................................14 2.2.2 Transmit Monitoring................................................................................15 2.2.3 Transmit Drivers .....................................................................................15 2.2.4 Transmit Idle Mode.................................................................................15 2.2.5 Transmit Pulse Shape ............................................................................15 Receiver ..............................................................................................................16 2.3.1 Receive Equalizer ..................................................................................16 2.3.2 Receive Data Recovery..........................................................................16 2.3.3 Receive Digital Data Interface................................................................16 2.3.4 Receiver Monitor Mode ..........................................................................16 Jitter Attenuation .................................................................................................16 Hardware Mode...................................................................................................17 Host Mode ...........................................................................................................17 2.6.1 Interrupt Handling...................................................................................18 Diagnostic Mode Operation.................................................................................20 2.7.1 Loopback Modes ....................................................................................21 2.7.2 Internal Pattern Generation and Detection.............................................24 2.7.3 Error Insertion and Detection .................................................................26 2.7.4 Alarm Condition Monitoring ....................................................................27 2.7.5 Other Diagnostic Reports .......................................................................28 3.0 Register Definitions.................................................................................................29 4.0 Application Information .........................................................................................34 4.1 4.2 4.3 Transmit Return Loss ..........................................................................................34 Transformer Data ................................................................................................34 Application Circuits..............................................................................................34 4.3.1 Hardware Mode Circuit...........................................................................35 4.3.2 Host Mode Circuit...................................................................................36 5.0 Test Specifications ..................................................................................................38 6.0 Mechanical Specifications....................................................................................46 Datasheet 3 LXT362 — Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications Figures 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 4 LXT362 Block Diagram ......................................................................................... 7 LXT362 Pin Assignments...................................................................................... 8 50% Duty Cycle Coding ...................................................................................... 15 Serial Port Data Structure ................................................................................... 19 TAOS with LLOOP .............................................................................................. 21 Local Loopback ................................................................................................... 22 Analog Loopback ................................................................................................ 22 Remote Loopback ............................................................................................... 23 Dual Loopback .................................................................................................... 24 TAOS Data Path ................................................................................................. 24 QRSS Mode ........................................................................................................ 25 Typical Hardware Mode Application.................................................................... 36 Typical Host Mode Application............................................................................ 37 1.544 MHz T1 Pulse (DS1 and DSX-1) (See Table 25) ...................................... 40 Transmit Clock Timing ........................................................................................ 41 Receive Clock Timing ......................................................................................... 42 Serial Data Input Timing Diagram ....................................................................... 43 Serial Data Output Timing Diagram .................................................................... 43 Typical T1 Jitter Tolerance at 36 dB ................................................................... 44 T1 Jitter Attenuation ............................................................................................ 45 Plastic Leaded Chip Carrier Package Specifications .......................................... 46 Plastic Quad Flat Package Specifications........................................................... 47 Low-Profile Quad Flat Package Specifications ................................................... 48 Datasheet Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications — LXT362 Tables 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 Datasheet LXT362 Clock and Data Pins by Mode1 ............................................................... 9 LXT362 Control Pins by Mode ..............................................................................9 LXT362 Signal Descriptions ................................................................................10 CLKE Pin Settings1.............................................................................................18 Control and Operational Mode Selection ............................................................19 Diagnostic Mode Availability................................................................................20 Register Addresses .............................................................................................29 Register and Bit Summary ..................................................................................29 Control Register #1 Read/Write, Address (A7-A0) = x010000x ..........................30 Equalizer Control Input Settings..........................................................................30 Control Register #2 Read/Write, Address (A7-A0) = x010001x ..........................31 Control Register #3 Read/Write, Address (A7-A0) = x010010x ..........................31 Interrupt Clear Register Read/Write, Address (A7-A0) = x010011x....................32 Transition Status Register Read Only, Address (A7-A0) = x010100x.................32 Performance Status Register Read Only, Address (A7-A0) = x010101x ............33 Equalizer Status Register Read Only, Address (A7-A0) = x010110x .................33 Control Register #4 Read/Write, Address (A7-A0) = x010111x ..........................33 Transmit Return Loss ..........................................................................................34 Transformer Specifications for LXT362...............................................................34 Recommended Transformers for LXT362...........................................................35 Absolute Maximum Ratings.................................................................................38 Recommended Operating Conditions .................................................................38 Digital Characteristics..........................................................................................39 Analog Characteristics ........................................................................................39 1.544 MHz T1 Pulse Mask Corner Point Specifications......................................40 Master and Transmit Clock Timing Characteristics (See Figure 15)...................40 Receive Timing Characteristics (See Figure 16).................................................41 Serial I/O Timing Characteristics (See Figure 17 and Figure 18)........................42 5 LXT362 — Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications Revision History Revision 6 Date Description Datasheet Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications — LXT362 Figure 1. LXT362 Block Diagram 4 EC4-1 TTIP INTERNAL PATTERN GENERATOR (QRSS) TCLK TPOS TNEG MODE QRSS ENABLE B8ZS/HDB3 UNIPOLAR ENCODER TRANSMIT TIMING CONTROL JA IF SELECTED TAOS ENABLE ENCODER ENABLE TRANSMIT ATTENUATION & FILTER LINE DRIVERS TRING INT CLKE EC Select SERIAL PORT CONTROL/STATUS REGISTERS CONTROL NLOOP ENABLE TRSTE RLOOP ENABLE LLOOP ENABLE REMOTE LOOPBACK MCLK QPD ENABLE RCLK JA IF SELECTED RNEG INTERNAL PATTERN DETECTOR NLOOP LOS/ QPD Datasheet INBAND NLOOP DETECTOR QPD SDO CLOCK GENERATOR AIS ENABLE/ REPORT ANALOG LOOPBACK EQUALIZER CONTROL TIMING & DATA RECOVERY GAIN RTIP SLICERS & PEAK DETECTORS LOS PROCESSOR SDI ALOOP ENABLE DECODER ENABLE B8ZS/HDB3 UNIPOLAR DECODER RPOS SCLK CS EC1/ EGL LOCAL LOOPBACK JITTER ATTENUATOR JASEL MONITOR NOISE & CROSSTALK FILTER RECEIVE EQUALIZER RRING AIS DETECTOR LOS 7 LXT362 — Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications 1.0 Pin Assignments and Signal Descriptions TNEG / INSBPV TPOS / TDATA / INSLER TCLK MCLK TAOS / CLKE / QRSS LLOOP / SCLK RLOOP / CS Figure 2. LXT362 Pin Assignments 4 3 2 1 28 27 26 5 25 EC3 / SDO RNEG / BPV 6 24 EC2 / SDI RPOS / RDATA 7 23 EC1 / INT 22 GND 21 VCC 20 RRING 19 RTIP 18 NLOOP TRING 17 n/c 16 EC3 / SDO 15 EC4 14 LLOOP / SCLK 13 RLOOP / CS TPOS / TDAT /INSLER TNEG / INSBPV n/c LOS / QPD 12 TAOS / CLKE / QRSS 11 TVCC 10 JASEL TGND n/c LXT362PEXX LXT362PE XXXXXX XXXXXXXX MCLK 9 n/c 8 TRSTE TTIP RCLK TCLK MODE 44 43 42 41 40 39 38 37 36 35 34 n/c 1 33 n/c MODE 2 32 EC2 / SDI RNEG / BPV 3 31 EC1 / INT RPOS / RDATA 4 30 n/c RCLK 5 n/c 6 TRSTE LXT362QE XX LXT362QE LXT362LE XX XXXXXX LXT362LE 29 GND 28 n/c 7 27 VCC n/c 8 26 n/c n/c 9 25 RRING JASEL 10 24 RTIP n/c 11 23 n/c n/c NLOOP EC4 TRING TVCC n/c TGND TTIP n/c n/c 8 LOS / QPD 12 13 14 15 16 17 18 19 20 21 22 Datasheet Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications — LXT362 1.1 Mode Dependent Signals As shown in Figure 2, the LXT362 has various signal pins that change function (and name) according to the selected mode(s) of operation. These pins, associated signal names and operating modes are summarized in Table 1 and Table 2. LXT362 signals are described in Table 3. LXT362 Clock and Data Pins by Mode1 Table 1. Pin # External Data Modes Bipolar Mode QRSS Modes PLCC QFP Unipolar Mode Bipolar Mode Unipolar Mode 1 39 2 41 3 42 TPOS TDATA INSLER 4 43 TNEG INSBPV INSBPV 6 3 RNEG BPV 7 4 RPOS RDATA 8 5 RCLK 13 15 TTIP 16 19 TRING 19 24 RTIP 20 25 RRING MCLK TCLK RNEG BPV RPOS RDATA 1. Data pins change based on whether external data or internal QRSS mode is active. Clock pins remain the same in both Hardware and Host modes. Table 2. Pin # LXT362 Control Pins by Mode Hardware Modes Unipolar/ Bipolar PLCC QFP QRSS 5 2 MODE 9 7 11 10 12 13 Host Modes Unipolar/ Bipolar Hardware Modes MODE 25 35 EC3 SDO TRSTE TRSTE 17 20 EC4 Low JASEL Low 18 21 NLOOP NLOOP 26 36 RLOOP CS LLOOP SCLK LOS/ QPD LOS/ QPD LOS 23 31 EC1 INT 27 37 32 EC2 SDI 28 38 TAOS QRSS Unipolar/ Bipolar QFP 24 Datasheet Unipolar/ Bipolar Host Modes PLCC LOS QRSS Pin # QRSS QRSS CLKE 9 LXT362 — Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications Table 3. LXT362 Signal Descriptions Pin # Symbol PLCC I/O1 Description QFP 1 39 MCLK DI Master Clock. External, independent 1.544 MHz clock signal required to generate internal clocks. MCLK must be jitter-free and have an accuracy better than ± 50 ppm with a typical duty cycle of 50%. Upon Loss of Signal (LOS), RCLK is derived from MCLK. 2 41 TCLK DI Transmit Clock. A 1.544 MHz clock is required. The transceiver samples TPOS and TNEG on the falling edge of TCLK (or MCLK, if TCLK is not present). BIPOLAR MODES: Transmit – Positive and Negative. TPOS and TNEG are the positive and negative sides of a bipolar input pair. Data to be transmitted onto the twisted-pair line is input at these pins. TPOS/TNEG are sampled on the falling edge of TCLK (or MCLK, if TCLK is not present). UNIPOLAR MODES: 3 42 TPOS / TDATA / INSLER DI 4 43 TNEG / INSBPV DI Transmit Data. TDATA carries unipolar data to be transmitted onto the twisted-pair line and is sampled on the falling edge of TCLK. Transmit Insert Logic Error. In QRSS mode, a Low-to-High transition on INSLER inserts a logic error into the transmitted QRSS data pattern. The inserted error follows the data flow of the active loopback mode. The LXT362 samples this pin on the falling edge of TCLK (or MCLK, if TCLK is not present). Transmit Insert Bipolar Violation. INSBPV is sampled on the falling edge of TCLK (or MCLK, if TCLK is not present) to control Bipolar Violation (BPV) insertions in the transmit data stream. A Low-to-High transition is required to insert each BPV. In QRSS mode, the BPV is inserted into the transmitted QRSS pattern. 5 2 MODE DI Mode Select. Connect Low to select Hardware mode. Connect High to select Host mode. See Table 5 on page 19 for a complete list of operating modes. BIPOLAR MODES: 6 3 RNEG / BPV DO 7 4 RPOS / RDATA DO Receive – Negative and Positive. RPOS and RNEG are the positive and negative sides of a bipolar output pair. Data recovered from the line interface is output on these pins. A signal on RNEG corresponds to receipt of a negative pulse on RTIP/RRING. A signal on RPOS corresponds to receipt of a positive pulse on RTIP/RRING. RNEG/RPOS are Non-Returnto-Zero (NRZ). In Hardware mode, RPOS/RNEG are stable and valid on the rising edge of RCLK. In Host mode, the CLKE pin selects the RCLK clock edge when RPOS /RNEG are stable and valid as described in Table 4 on page 18. UNIPOLAR MODES: Receive Bipolar Violation. BPV goes High to indicate detection of a bipolar violation from the line. This is an NRZ output and is valid on the rising edge of RCLK. Receive Data. RDATA is the unipolar NRZ output of data recovered from the line interface. In Hardware mode, RDATA is stable and valid on the rising edge of RCLK. In Host mode, the CLKE pin selects the RCLK clock edge when RDATA is stable and valid as described in Table 4 on page 18. 8 5 RCLK DO Receive Recovered Clock. The clock recovered from the line input signal is output on this pin. Under LOS conditions, there is a smooth transition from the RCLK signal (derived from the recovered data) to the MCLK signal, which appears at the RCLK pin. 1. DI = Digital Input; DO = Digital Output; DI/O = Digital Input/Output; AI = Analog Input; AO = Analog Output. 2. Midrange is a voltage level such that 2.3 V ≤ Midrange ≤ 2.7 V. Midrange may also be established by letting the pin float. 10 Datasheet Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications — LXT362 Table 3. LXT362 Signal Descriptions (Continued) Pin # Symbol PLCC I/O1 Description QFP Tristate. HARDWARE MODES: 9 7 TRSTE DI Connect TRSTE High to force all output pins to the high impedance state. TRSTE, in conjunction with the MODE pin, selects the operating modes listed in Table 5 on page 19. HOST MODES: Connect TRSTE High to force all output pins to the high-impedance state. Connect this pin Low for normal operation. HARDWARE MODES: Jitter Attenuation Select. Selects jitter attenuation location: 11 10 JASEL DI Setting JASEL High activates the jitter attenuator in the receive path. Setting JASEL Low activates the jitter attenuator in the transmit path. Setting JASEL to Midrange2 disables jitter attenuation. HOST MODES: Connect Low in Host mode. Loss of Signal Indicator. LOS goes High upon receipt of 175 consecutive spaces and returns Low when the received signal reaches a mark density of 12.5% (determined by receipt of 16 marks within a sliding window of 128 bits with fewer than 100 consecutive zeros). Note that the transceiver outputs received marks on RPOS and RNEG even when LOS is High. 12 13 LOS / QPD 13 15 TTIP 16 19 TRING 14 16 TGND - Ground return for the transmit driver power supply TVCC. 15 18 TVCC - +5 VDC Power Supply for the transmit drivers. TVCC must not vary from VCC by more than ± 0.3 V. DO AO QRSS Pattern Detect. In QRSS mode, QPD stays High until the transceiver detects a QRSS pattern. When a QRSS pattern is detected, the pin goes Low. Any bit errors cause QPD to go High for half a clock cycle. This output can be used to trigger an external error counter. Note that a LOS condition will cause QPD to remain High. See Figure 11. Transmit Tip and Ring. Differential driver output pair designed to drive a 50 - 200 Ω load. The transformer and line matching resistors should be selected to give the desired pulse height and return loss performance. See “Application Information” on page 34. HARDWARE MODES: 17 20 EC4 DI Equalization Control 4. Used along with EC3, EC2 and EC1 pins to specify pulse equalization, line build out and equalizer gain limit settings. See Table 10 on page 30 for details. HOST MODES: Connect Low in Host mode. 18 21 NLOOP 19 24 RTIP 20 25 RRING 21 27 VCC DO Network Loopback Active. Goes High to indicate that Network loopback (NLOOP) is active. NLOOP is activated by the reception of a 00001 pattern for five seconds. NLOOP is reset by reception of a 001 pattern for five seconds, or by activation of Remote loopback (RLOOP). AI Receive Tip and Ring. The Alternate Mark Inversion (AMI) signal received from the line is applied at these pins. A 1:1 transformer is required. Data and clock recovered from RTIP/RRING are output on the RPOS/RNEG (or RDATA in Unipolar mode), and RCLK pins. - +5 VDC Power Supply for all circuits except the transmit drivers. Transmit drivers are supplied by TVCC. 1. DI = Digital Input; DO = Digital Output; DI/O = Digital Input/Output; AI = Analog Input; AO = Analog Output. 2. Midrange is a voltage level such that 2.3 V ≤ Midrange ≤ 2.7 V. Midrange may also be established by letting the pin float. Datasheet 11 LXT362 — Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications Table 3. LXT362 Signal Descriptions (Continued) Pin # PLCC QFP 22 29 Symbol I/O1 GND - Description Ground return for power supply VCC. HARDWARE MODES: Equalization Control 1-3. EC1, EC2, and EC3 (along with the EC4 pin) specify the pulse equalization, line build out and equalizer gain limit settings. See Table 10 on page 30 for details. HOST MODES: 23 31 EC1 / INT 24 32 EC2 / SDI DI 25 35 EC3 / SDO DI/O DI Interrupt. INT goes Low to flag the host when LOS, AIS, NLOOP, QRSS, DFMS or DFMO bits changes state, or when an elastic store overflow or underflow occurs. To identify the specific interrupt, read the Performance Status Register (PSR). To clear or mask an interrupt, write a one to the appropriate bit in the Interrupt Clear Register (ICR). To re-enable the interrupt, write a zero. INT is an open drain output that must be connected to VCC through a pull-up resistor. Serial Data Input. SDI inputs the 16-bit serial address/command and data word. SDI is sampled on the rising edge of SCLK. Timing is shown in Figure 17 on page 43. Serial Data Output. SDO outputs the 8-bit serial data read from the selected LXT362 register. When the CLKE pin is High, SDO is valid on the rising edge of SCLK. When CLKE is Low, SDO is valid on the falling edge of SCLK. SDO goes to a high-impedance state when the serial port is being written to or when CS is High. Timing is shown in Figure 18 on page 43. HARDWARE MODES: 26 36 RLOOP / CS DI Remote Loopback. When held High, the clock and data inputs from the framer (TPOS/TNEG or TDATA) are ignored and the data received from the twisted-pair line is transmitted back onto the line at the RCLK frequency. Connect to Midrange2 to enable In-band Network loopback detection (NLOOP). HOST MODES: Chip Select. CS is used to access the serial interface. For each read or write operation, CS must transition from High to Low, and remain Low. 1. DI = Digital Input; DO = Digital Output; DI/O = Digital Input/Output; AI = Analog Input; AO = Analog Output. 2. Midrange is a voltage level such that 2.3 V ≤ Midrange ≤ 2.7 V. Midrange may also be established by letting the pin float. 12 Datasheet Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications — LXT362 Table 3. LXT362 Signal Descriptions (Continued) Pin # Symbol PLCC I/O1 Description QFP HARDWARE MODES: 27 37 LLOOP / SCLK DI Local Loopback. When held High, the data on TPOS and TNEG loops back digitally to the RPOS and RNEG outputs (through the JA if enabled). Connecting this pin to Midrange2 enables Analog loopback (TTIP and TRING are looped back to RTIP and RRING). HOST MODES: Serial Clock. SCLK synchronizes serial port read/write operations. The clock frequency can be any rate up to 2.048 MHz. HARDWARE MODES: Transmit All Ones. When held High, the transmit data inputs are ignored and the LXT362 transmits a stream of 1’s at the TCLK frequency. If TCLK is not supplied, MCLK becomes the transmit clock reference. Note that TAOS is inhibited during Remote loopback. 28 38 TAOS / QRSS / CLKE DI QRSS. In QRSS mode, setting this pin to Midrange2, enables QRSS pattern generation and detection. The transceiver transmits the QRSS pattern at the TCLK rate (or MCLK, if TCLK is not present). HOST MODES: Clock Edge Select. When CLKE is High, RPOS/RNEG or RDATA are valid on the falling edge of RCLK, and SDO is valid on the rising edge of SCLK. When CLKE is Low, RPOS/RNEG or RDATA are valid on the rising edge of RCLK, and SDO is valid on the falling edge of SCLK. The operation of CLKE is summarized in Table 4 on page 18. 10 1, 6, 8, 9, 11, 12, 14, 17, 22, 23, 26, 28, 30, 33, 34, 40, 44 n/c - Not Connected 1. DI = Digital Input; DO = Digital Output; DI/O = Digital Input/Output; AI = Analog Input; AO = Analog Output. 2. Midrange is a voltage level such that 2.3 V ≤ Midrange ≤ 2.7 V. Midrange may also be established by letting the pin float. Datasheet 13 LXT362 — Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications 2.0 Functional Description The LXT362 is a fully integrated, PCM transceiver for long- or short-haul, 1.544 Mbps (T1) applications allowing full-duplex transmission of digital data over existing twisted-pair installations. It interfaces with two twisted-pair lines (one pair each for transmit and receive) through standard pulse transformers and appropriate resistors. The figure on the front page of this data sheet shows a block diagram of the LXT362. The designer can configure the device for either Host or Hardware control. In Host mode, control is via the serial microprocessor port. In Hardware mode, individual pin settings allow stand-alone operation. The transceiver provides a high-precision, crystal-less jitter attenuator. The user may place it in the transmit or receive path, or bypass it completely. The LXT362 meets or exceeds FCC, ANSI T1 and AT&T specifications for CSU and DSX-1 applications. 2.1 Initialization During power up, the transceiver remains static until the power supply reaches approximately 3 V. Upon crossing this threshold, the device begins a 32 ms reset cycle to calibrate the Phase Lock Loops (PLL). The transceiver uses a reference clock to calibrate the PLLs: the transmitter reference is TCLK, and the receiver reference clock is MCLK. MCLK is mandatory for chip operation and must be an independent free running jitter free reference clock. 2.1.1 Reset Operation A reset operation initializes the status and state machines for the LOS, AIS, NLOOP, and QRSS blocks. In Hardware mode, holding pins RLOOP, LLOOP and TAOS High for at least one clock cycle resets the device. In Host mode, writing a 1 to the bit CR2.RESET commands a reset which clears all registers to 0. Allow 32 ms for the device to settle after removing all reset conditions. 2.2 Transmitter 2.2.1 Transmit Digital Data Interface Input data for transmission onto the line is clocked serially into the device at the TCLK rate. TPOS and TNEG are the bipolar data inputs. In Unipolar mode, the TDATA pin accepts unipolar data. Input data may pass through either the Jitter Attenuator or B8ZS the encoder or both. In Host mode, setting CR1.ENCENB = 1 enables B8ZS encoding. In Hardware mode, connecting the MODE pin to Midrange selects zero suppression coding. With zero suppression enabled, the EC1 through EC4 inputs determine the coding scheme as listed in Table 10 on page 30. TCLK supplies input synchronization. See the Figure 15 on page 41 for the transmit timing requirements for TCLK and the Master Clock (MCLK). 14 Datasheet Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications — LXT362 2.2.2 Transmit Monitoring In Host mode, the Performance Status Register flags open circuits in bit PSR.DFMO. A transition on DFMO will provide an interrupt, and its transition sets bit TSR.DFMO = 1. Writing a 1 in bit ICR.CDFMO clears the interrupt; leaving a 1 in the bit masks that interrupt. 2.2.3 Transmit Drivers The transceiver transmits data as a 50% line code as shown in Figure 3. To reduce power consumption, the line driver is active only during transmission of marks, and is disabled during transmission of spaces. Biasing of the transmit DC level is on-chip. Figure 3. 50% Duty Cycle Coding Bit Cell 1 2.2.4 0 1 Transmit Idle Mode Transmit Idle mode allows multiple transceivers to be connected to a single line for redundant applications. When TCLK is not present, Transmit Idle mode becomes active, and TTIP and TRING change to the high impedance state. Remote loopback, Dual loopback, TAOS, or detection of Network Loop Up code in the receive direction will temporarily disable the high impedance state. 2.2.5 Transmit Pulse Shape As shown in Table 10 on page 30, Equalizer Control inputs (EC1 through EC4) determine the transmitted pulse shape. In Host mode, EC1 through 4 are established by bits 0 through 3 of Control Register #1 (CR1), respectively. In Hardware mode, pins EC1, EC2, EC3, and EC4 specify pulse shape. Shaped pulses meeting the various T1, DS1, and DSX-1 specifications are applied to the AMI line driver for transmission onto the line at TTIP and TRING. The transceiver produces DSX-1 pulses for short-haul T1 applications (settings from 0 dB to +6.0 dB of cable), DS1 pulses for long-haul T1 applications (settings from 0 dB to -22.5 dB). Refer to Figure 14 on page 40 for pulse mask specifications. Datasheet 15 LXT362 — Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications 2.3 Receiver A 1:1 transformer provides the interface to the twisted-pair line (RTIP/RING). Recovered data is output at RPOS/RNEG (RDATA in Unipolar mode), and the recovered clock is output at RCLK. Refer to Table 27 on page 41 for receiver timing specifications. 2.3.1 Receive Equalizer The receive equalizer processes the signal received at RTIP and RRING. The equalizer gain is up 36 dB. As shown in Table 10, Equalizer Control inputs (EC1 through EC4) determine the maximum gain applied to the equalizer. In Host mode, EC1 through 4 are established by bits 0 through 3 of Control Register #1 (CR1), respectively. In Hardware mode, pins EC1, EC2, EC3, and EC4 specify equalizer gain setting. With EC1 Low, up to 36 dB of gain may be applied. When EC1 is High, 26 dB is the gain limit to provide an increased noise margin in shorter loop operations. 2.3.2 Receive Data Recovery The transceiver filters the equalized signal and applies it to the peak detector and data slicers. The peak detector samples the inputs and determines the maximum value of the received signal. The data slicers are set at 50% of the peak value to ensure optimum signal-to-noise performance. After processing through the data slicers, the received signal goes to the data and timing recovery section, then to the B8ZS decoder (if selected) and to the receive monitor. The data and timing recovery circuits provide input jitter tolerance significantly better than required by AT&T Pub 62411. See “Test Specifications” on page 38 for details. 2.3.3 Receive Digital Data Interface Recovered data is routed to the Loss of Signal (LOS) Monitor. In Host mode, it also goes through the Alarm Indication Signal (AIS, Blue Alarm) Monitor. The jitter attenuator (JA) may be enabled or disabled in the receive data path or the transmit path. Received data can be routed to the B8ZS decoder or bypassed. Finally, the device may send the digital data to the framer as either unipolar or bipolar data. 2.3.4 Receiver Monitor Mode The receive equalizer can be used in Monitor mode applications. Monitor mode applications require 20 dB to 30 dB resistive attenuation of the signal, plus a small amount of cable attenuation (less than 6 dB). In Host mode, setting bit CR3.EQZMON = 1 configures the device to operate in Monitor mode. Note that the LXT362 must be in long-haul receiver mode (set bits CR1.EC4:1 = 0xx0, 1001, or 1010) to enable Monitor mode. Note that the Monitor mode feature is not available in Hardware mode. 2.4 Jitter Attenuation A Jitter Attenuation Loop (JAL) with an Elastic Store (ES) provides the jitter attenuation function. The JAL requires no special circuitry, such as an external quartz crystal or high-frequency clock (higher than the line rate). Rather, its timing reference is MCLK. 16 Datasheet Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications — LXT362 In Hardware mode, the ES is a 32 x 2-bit register. Setting the JASEL pin High places the JA circuitry in the receive data path; setting JASEL Low places the JA in the transmit data path; setting it to Midrange disables the JA. In Host mode, bit CR1.JASEL0 enables or disables the JA circuit while bit CR1.JASEL1 controls the JA circuit placement as specified in Table 9 on page 30. The ES can be either a 32 x 2-bit or 64 x 2-bit register depending on the value of bit CR3.ES64 (see Table 12). The device clocks data into the ES using either TCLK or RCLK depending on whether the JA circuitry is in the transmit or receive data path, respectively. Data is shifted out of the elastic store using the dejittered clock from the JAL. When the FIFO is within two bits of overflowing or underflowing, the ES adjusts the output clock by 1/8 of a bit period. The ES produces an average delay of 16 bits in the data path. An average delay of 32 bits occurs when the 64-bit ES option selected (Host mode only). In the event of a LOS condition, with the Jitter Attenuator in the receive path, RCLK will be derived from MCLK. Transition Status Register bits TSR.ESOVR and TSR.ESUNF indicate an elastic store overflow or underflow, respectively. Note that these are “sticky bits”, that is, once set to 1, they remain set until the host reads the register. An ES overflow or underflow condition will generate a maskable interrupt. 2.5 Hardware Mode The LXT362 operates in Hardware mode when the MODE pin is set to Low or Midrange. In Hardware mode individual pins are used to access and control the transceiver. In Hardware mode, RPOS/RNEG or RDATA are valid on the rising edge of RCLK. Note that some functions, such as interrupt (INT), clock edge selection (CLKE), and various diagnostic modes, are provided only in Host mode. 2.6 Host Mode The LXT362 operates in Host mode when the MODE pin is set High. In Host mode a microprocessor controls the LXT362 and reads its status via the serial port which provides access to the LXT362’s internal registers. The host microprocessor can completely configure the device, as well as get a full diagnostic/status report, via the serial port. However, in Unipolar mode, bipolar violation (BPV) insertions and logic error insertions are controlled by the BPV and INSLER pins, respectively. Similarly, the recovered clock, data, and BPV detection are available only at output pins. All other mode settings and diagnostic information are available via the serial port. See “Register Definitions” on page 29 for details. Figure 4 shows the serial port data structure. The registers are accessible through a 16-bit word composed of an 8-bit Command/Address byte (bits R/W and A1-A7) and a subsequent 8-bit data byte (bits D0-7). The R/W bit commands a read or a write operation, i.e., the direction of the following byte. Bits A1 through A6, of the command/address byte, point to a specific register. Note that the LXT362 address decoder ignores bits A0 and A7. Refer to Table 28 on page 42 for timing specifications. Host mode also allows control of data output timing. The CLKE pin determines when SDO is valid, relative to the Serial Clock (SCLK) as shown in Table 4. Datasheet 17 LXT362 — Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications 2.6.1 Interrupt Handling In Host mode, the LXT362 provides a latched interrupt output pin (INT). When enabled, a change in any of the Performance Status Register bits will generate an interrupt. An interrupt can also be generated when the elastic store overflows (TSR.ESOVR) or underflows (TSR.ESUNF). When an interrupt occurs, the INT output pin is pulled Low. Note that the output stage of the INT pin has internal pull-down only. Therefore, each device that shares the INT line requires an external pull-up resistor. The interrupt is cleared when the interrupt condition no longer exists, and the host processor writes a 1 to the respective interrupt causing bit(s) in the Interrupt Clear Register (ICR). Leaving a 1 in any of the ICR bits masks that interrupt. To re-enable an interrupt bit, write a 0. Table 4. CLKE Pin Settings1 CLKE Pin Output Valid Clock Edge RPOS RNEG Rising RCLK Low RDATA SDO Falling SCLK RPOS RNEG Falling RCLK High RDATA SDO Rising SCLK 1. The clock edge selection feature is not available in Hardware mode. 18 Datasheet Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications — LXT362 Figure 4. Serial Port Data Structure CS SCLK Address / Command Byte Input (Write) Data Byte A7 SDI R/W A1 A2 A3 A4 A5 A6 (don’t care) High Impedance SDO D0 D1 D2 D3 D4 D5 D6 D7 D0 D1 D2 D3 D4 D5 D6 D7 R/W = 1: Read operation R/W = 0: Write operation (SDO remains high impedance) Output (Read) Data Byte . Table 5. Control and Operational Mode Selection Input to Pin1 Mode of Operation Mode TRSTE Hardware Host2 Unipolar Bipolar AMI Enc/Dec B8ZS Encoder/Decoder All Outputs Tristated Low Low On Off Off On Off3 Off No Low High On Off Off On Off3 Off Yes Low Open On Off On Off On Off No High Low Off On x x x x No High High Off On x x x x Yes High Open Off On x x x x No Open Low On Off On Off Off On No Open High On Off On Off Off On Yes Open Open On Off On Off Off On No 1. Open is either a midrange voltage or the pin is floating. 2. In Host mode, the contents of register CR1 determine the operation mode. 3. Encoding is done externally. Datasheet 19 LXT362 — Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications 2.7 Diagnostic Mode Operation The LXT362 offers multiple diagnostic modes as listed in Table 6. Note that various diagnostic modes are only available in Host mode. In Hardware mode, the diagnostic modes are selected by a combination of pin settings. In Host mode, the diagnostic modes are selected by writing appropriate bits in the Diagnostic Control Register (DCR). The following paragraphs provide details of the diagnostic modes. Table 6. Diagnostic Mode Availability Availability1 Diagnostic Mode Host Mode Maskable2 Hardware Host Local Loopback (LLOOP) Yes Yes No Analog Loopback (ALOOP) Yes Yes No Remote Loopback (RLOOP) Yes Yes No In-band Network Loopback (NLOOP) Yes Yes Yes Dual Loopback (DLOOP) Yes Yes No Loopback Modes Internal Data Pattern Generation and Detection Transmit All Ones (TAOS) Yes Yes No Quasi-Random Signal Source (QRSS) Yes Yes Yes In-band Loop up/down Code Generator No Yes No Error Insertion and Detection Bipolar Violation Insertion (INSBPV) Yes Yes No Logic Error Insertion (INSLER) Yes Yes No Bipolar Violation Detection (BPV) Yes Yes No Logic Error Detection, QRSS (QPD) Yes Yes No Receive Loss of Signal (LOS) Monitoring Yes Yes Yes Receive Alarm Indication Signal (AIS) Monitoring No Yes Yes Transmit Driver Failure Monitoring—Open (DFMO) No Yes Yes Elastic Store Overflow and Underflow Monitoring No Yes Yes Receive Line Attenuation Indicator (LATN) No Yes No Built-In Self Test (BIST) No Yes Yes Alarm Condition Monitoring Other Diagnostic Reports 1. In Hardware mode, a combination of pin settings selects the Diagnostics Modes. In Host mode, writing appropriate bits in the Control Registers selects the Diagnostic Modes. 2. Host mode allows interrupt masking by writing a “1” to the corresponding bit in the Interrupt Clear Register. 20 Datasheet Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications — LXT362 2.7.1 Loopback Modes 2.7.1.1 Local Loopback (LLOOP) See Figure 5 and Figure 6. LLOOP inhibits the receiver circuits. The transmit clock and data inputs (TCLK and TPOS/TNEG or TDATA) loop back through the jitter attenuator (if enabled) and appear at RCLK and RPOS/RNEG or RDATA. Note that during LLOOP, the JASEL input is strictly an enable/disable control, i.e. it does not affect the placement of the JA. If the JA is enabled, it is active in the loopback circuit. If the JA is bypassed, it is not active in the loopback circuit. The transmitter circuits are unaffected by LLOOP and the LXT362 continues to transmit the TPOS/TNEG or TDATA inputs (or a stream of 1’s if TAOS is asserted). When used in this mode, the transceiver can function as a stand-alone jitter attenuator. In Hardware mode, Local loopback (LLOOP) is selected by setting LLOOP High; in Host mode, by setting bit CR2.ELLOOP = 1. Figure 5. TAOS with LLOOP Datasheet 21 LXT362 — Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications Figure 6. Local Loopback ENCODER* Local Loopback with JA in Receive Path DECODER* TCLK TPOS TNEG RCLK RPOS RNEG Timing & Control TTIP TRING * If Enabled JA* Timing Recovery RTIP RRING ENCODER* Local Loopback with JA in Transmit Path RCLK RPOS RNEG 2.7.1.2 JA* Timing & Control TTIP TRING * If Enabled DECODER* TCLK TPOS TNEG Timing Recovery RTIP RRING Analog Loopback (ALOOP) See Figure 7. Analog loopback (ALOOP) exercises the maximum number of functional blocks. ALOOP operation disconnects the RTIP/RRING inputs from the line and routes the transmit outputs back into the receive inputs. This tests the encoders/decoders, jitter attenuator, transmitter, receiver and timing recovery sections. In Hardware mode, ALOOP becomes active when the LLOOP pin is floating (i.e. Midrange). In Host mode, setting bit CR2.EALOOP = 1 commands ALOOP. Note that ALOOP overrides all other loopback modes. Figure 7. Analog Loopback RCLK RPOS RNEG DECODER* TCLK TPOS TNEG ENCODER* Analog Loopback with JA in Receive Path TTIP TRING * If Enabled JA* Timing Recovery RTIP RRING RCLK RPOS RNEG 22 DECODER* TCLK TPOS TNEG ENCODER* Analog Loopback with JA in Transmit Path TTIP JA* TRING * If Enabled Timing Recovery RTIP RRING Datasheet Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications — LXT362 2.7.1.3 Remote Loopback (RLOOP) See Figure 8. When RLOOP is active, the device ignores the transmit data and clock inputs (TCLK and TPOS/TNEG or TDATA), and bypasses the in-line encoders/decoders. The RPOS/RNEG or RDATA outputs loop back through the transmit circuits to TTIP and TRING at the RCLK frequency. The RLOOP command does not affect the receiver circuits which continue to output the RCLK and RPOS/RNEG or RDATA signals received from the twisted-pair line. In Host mode, command RLOOP by writing a 1 to bit CR2.ERLOOP. In Hardware mode, RLOOP is commanded by setting the RLOOP pin High. 2.7.1.4 Network Loopback (NLOOP) NLOOP can be initiated only when the Network loopback detect function is enabled. With NLOOP detection enabled, the receiver looks for the NLOOP data patterns (00001 = enable, 001 = disable) in the input data stream. The LXT362 responds to both framed and unframed NLOOP patterns. When the receiver detects the NLOOP enable data pattern repeated for a minimum of five seconds, loopback is activated. Once activated, operation is identical to Remote loopback (RLOOP). In Host mode, setting bit CR2.ENLOOP = 1 enables NLOOP detection. In Hardware mode, setting the RLOOP pin to Midrange enables NLOOP detection. NLOOP is disabled upon reception of the 001 pattern for five seconds, or by activating RLOOP or ALOOP, or by disabling NLOOP detection. Note that the LXT362 enters Dual loopback mode (DLOOP) when both NLOOP and LLOOP functions are selected. Figure 8. Remote Loopback Remote Loopback with JA in Receive Path TCLK TPOS TNEG RCLK RPOS RNEG Timing & Control * If Enabled Timing JA* Recovery TTIP TRING RTIP RRING Remote Loopback with JA in Transmit Path TCLK TPOS TNEG RCLK RPOS RNEG 2.7.1.5 JA* Timing & Control * If Enabled Timing Recovery TTIP TRING RTIP RRING Dual Loopback (DLOOP) See Figure 9. In Hardware mode, DLOOP is selected by setting both the RLOOP and LLOOP pins High. In Host mode set bits CR2.ERLOOP = 1 and CR2.ELLOOP = 1. In DLOOP mode, the transmit clock and data inputs (TCLK and TPOS/TNEG or TDATA) loop back through the Jitter Datasheet 23 LXT362 — Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications Attenuator (unless disabled) to RCLK and RPOS/RNEG or RDATA. The data and clock recovered from the twisted-pair line loop back through the transmit circuits to TTIP and TRING without jitter attenuation. TCLK TPOS TNEG RCLK RPOS RNEG DECODER* ENCODER* Figure 9. Dual Loopback Timing & Control JA* TTIP TRING * If Enabled Timing Recovery 2.7.2 Internal Pattern Generation and Detection 2.7.2.1 Transmit All Ones (TAOS) RTIP RRING See Figure 10. When TAOS is active, the transceiver ignores the TPOS and TNEG inputs and transmits a continuous stream of 1’s at the TCLK frequency. When TCLK is not supplied, TAOS timing is derived from MCLK. This can be used as the Alarm Indication Signal (AIS–also called the Blue Alarm). Both TAOS and LLOOP can operate simultaneously as shown in Figure 5, however, RLOOP inhibits TAOS. When both TAOS and LLOOP are active, TCLK and TPOS/TNEG loop back to RCLK and RPOS/RNEG (through the jitter attenuator if enabled), and the all ones pattern is also routed to TTIP/TRING. In Host mode, TAOS is activated when bit CR2.ETAOS = 1. In Hardware mode, setting the TAOS pin High activates TAOS. Figure 10. TAOS Data Path TCLK TPOS TNEG RCLK RPOS RNEG 2.7.2.2 DECODER* ENCODER* TAOS Timing & Control TTIP TRING * If Enabled Timing Recovery RTIP RRING Quasi-Random Signal Source (QRSS) See Figure 11. The Quasi-Random Signal Source (QRSS) is a 220-1 pseudo-random bit sequence (PRBS) with no more than 14 consecutive zeros. Both Hardware and Host Modes allow QRSS mode. The QRSS pattern is normally locked to TCLK, however, if there is no TCLK, MCLK is the clock source. Bellcore Pub 62411 defines the T1 QRSS transmit format. 24 Datasheet Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications — LXT362 With QRSS transmission enabled, it is possible to insert a logic error into the transmit data stream by causing a Low-to-High transition on the INSLER pin. However, if no logic or bit errors are to be inserted into the QRSS pattern, INSLER must remain Low. Logic Error insertion waits until the next bit if the current bit is “jammed”. When there are more than 14 consecutive 0s, the output is jammed to a 1. A Low-to-High transition on the INSBPV pin will insert a bipolar violation in the QRSS pattern. Note that the BPV insertion occurs regardless of whether the device is in Bipolar or Unipolar operating mode. In Hardware mode, connecting the TAOS pin to Midrange enables QRSS transmission. In Host mode, setting bits CR2.EPAT0 = 0 and CR2.EPAT1=1 enables QRSS. Figure 11. QRSS Mode Selecting QRSS mode also enables QRSS Pattern Detection (QPD) in the receive path. The QRSS pattern is synchronized when there are fewer than four errors in 128 bits. After achieving synchronization the device drives the QPD pin Low. In the QRSS mode, any subsequent bit error in the QRSS pattern causes QPD to go High for half an RCLK clock cycle. Note that in Host mode, the precise relationship between QPD and RCLK depends on the CLKE pin. When CLKE is Low, QPD goes High while RCLK is High; when CLKE is High, QPD goes High while RCLK is Low. The edge of QPD can serve as a trigger for an external bit-error counter. A LOS condition or a loss of QRSS synchronization will cause QPD to go High continuously. In this case, and with either Unipolar mode or the encoders/decoders enabled, the BPV pin indicates BPVs, CODEVs or ZEROVs. Host mode can generate an interrupt to indicate that QRSS detection has occurred, or that synchronization is lost. This interrupt is enabled when bit ICR.CQRSS = 0. If the QPD signal is used to trigger a bit error counter, the interrupt could be used to start or reset the error counter. The PSR.QRSS bit provides an indication of QRSS pattern synchronization. This bit goes to 0 when the QRSS pattern is not detected (i.e., when there are more than four errors in 128 bits). The TQRSS bit in the Transition Status Register indicates that QRSS status has changed since the last QRSS Interrupt Clear command. Datasheet 25 LXT362 — Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications 2.7.2.3 In-Band Network Loop Up or Down Code Generator In-band Network Loop Up or Loop Down code transmission is available in Host mode only. The Loop Up code is 00001; Loop Down code is 001. A Loop Up code transmission occurs when bits CR2.EPAT0 = 1 and CR2.EPAT1 = 0. A Loop Down code transmission occurs when CR2.EPAT0 = 1 and CR2.EPAT1 = 1. With this mode is active, logic errors and bipolar violations can be inserted into the transmit data stream. Inserting a logic error requires a Low-to-High transition of the INSLER pin. If no logic or bit errors are to be inserted, INSLER must remain Low. A Low-to-High transition on the INSBPV pin will insert a bipolar violation, regardless of whether the device is in the Unipolar or Bipolar mode of operation. 2.7.3 Error Insertion and Detection 2.7.3.1 Bipolar Violation Insertion (INSBPV) The INSBPV function is available in Unipolar mode. Sampling occurs on the falling edge of TCLK. A Low-to-High transition on the INSBPV pin inserts a BPV on the next available mark, except in the four following situations: • When zero suppression (B8ZS) is not violated • When LLOOP and TAOS are both active. In this case, the BPV is looped back to the BPV pin and the line driver transmits all ones with no violation. • When RLOOP is active • When NLOOP is active Note that when the LXT362 is configured to transmit internally generated data patterns (QRSS or NLOOP), a BPV can be inserted on the transmit pattern regardless of whether the device is in the Unipolar or Bipolar mode of operation. 2.7.3.2 Logic Error Insertion (INSLER) When transmission of QRSS or NLOOP Up/Down codes are active, a logic error is inserted into the transmit data pattern when a Low-to-High transition occurs on the INSLER pin. Note that in QRSS mode, logic error insertion is inhibited on a jammed bit (i.e. a bit forced to one to suppress transmission of more than 14 consecutive zeros). The transceiver treats data patterns the same way it treats data applied to TPOS/TNEG. Therefore, the inserted logic error will follow the data flow path as defined by the active loopback mode 2.7.3.3 Logic Error Detection (QPD) After pattern synchronization is detected in QRSS mode, subsequent logic errors are reported on the QPD pin. If a logic error occurs, the QPD pin goes High for half an RCLK cycle. Note that in Host mode, the precise relationship between QPD and RCLK depends on the value of the CLKE pin. When CLKE is Low, QPD goes High while RCLK is High; when CLKE is High, QPD goes High while RCLK is Low. To tally logic errors, connect an error counter to QPD. A continuous High on this pin indicates loss of either the QRSS pattern lock or a LOS condition. “Quasi-Random Signal Source (QRSS)” on page 24 provides additional details on QRSS pattern lock criteria. 26 Datasheet Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications — LXT362 2.7.3.4 Bipolar Violation Detection (BPV) When the internal encoders/decoders are disabled or when configured in Unipolar mode, bipolar violations are reported at the BPV pin. BPV goes High for a full clock cycle to indicate receipt of a BPV. When the encoders/decoders are enabled, the LXT362 does not report bipolar violations due to the line coding scheme. 2.7.4 Alarm Condition Monitoring 2.7.4.1 Loss of Signal (LOS) The receiver LOS monitor loads a digital counter at the RCLK frequency. The count increments with each received 0 and the counter resets to 0 on receipt of a 1. When the count reaches “n” 0s, the LOS flag goes High, and the MCLK replaces the recovered clock at the RCLK output in a smooth transition. For Hardware mode, the number of 0s, n = 175. In Host mode, either 175 or 2048 may be selected by setting bit CR4.LOS2048. When the received signal has 12.5% 1’s density (16 marks in a sliding 128-bit period, with fewer than 100 consecutive 0s), the LOS flag returns Low and the recovered clock replaces MCLK at the RCLK output in another smooth transition. During LOS, the device sends received data to the RPOS/RNEG pins (or RDATA in Unipolar mode). In Hardware and Host modes, the LOS pin goes High when a LOS condition occurs. In Host mode, bit PSR.LOS =1 indicates a LOS condition, and will generate an interrupt if enabled. 2.7.4.2 Alarm Indication Signal Detection (AIS) This function is only available in Host mode. The receiver detects an AIS pattern when it receives fewer than three 0s in any string of 2048 bits. The device clears the AIS condition when it receives three or more 0s in a string of 2048 bits. The AIS bit in the Performance Status Register indicates AIS detection. Whenever the AIS status changes, bit TSR.TAIS =1. Unless masked, a change of AIS status generates an interrupt. 2.7.4.3 Driver Failure Monitor Open (DFMO) This function is only available in Host mode. The DFMO bit is available in the Performance Status Register to indicate an open condition on the lines. DFMO can generate an interrupt to the host controller. The Transition Status Register bit TDFMO indicates a transition in the status of the bit. Writing a 1 to ICR.CDFMO will clear or mask the interrupt. 2.7.4.4 Elastic Store Overflow/Underflow (ESOVR and ESUNF) This function is only available in Host mode. When the bit count in the Elastic Store (ES) is within two bits of overflowing or underflowing the ES adjusts the output clock by 1/8 of a bit period. The ES provides an indication of overflow and underflow via bits TRS.ESOVR and TSR.ESUNF. These are “sticky bits” and will stay set to 1 until the host controller reads the register. These interrupts can be cleared or masked by writing a 1 to the bits ICR.CESO and ICR.CESU, respectively. Datasheet 27 LXT362 — Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications 2.7.5 Other Diagnostic Reports 2.7.5.1 Receive Line Attenuation Indication This function is only available in Host mode. The Equalizer Status Register (ESR) provides an approximation of the line attenuation encountered by the device. The four MSBs of the register (ESR.LATN7:4) indicate line attenuation in approximately 2.9 dB steps for the receive equalizer. For instance, if ESR.LATN7:4 is 10 (decimal), then the receiver is seeing a signal attenuated by approximately 29 dB (2.9 dB x 10) of cable loss. 2.7.5.2 Built-In Self Test (BIST) The BIST function in only available in Host mode. The BIST exercises the internal circuits by providing an internal QRSS pattern, running it through the encoders and the transmit drivers then looping it back through the receive equalizer, jitter attenuator and decoders to the QRSS pattern detection circuitry. The BIST is initiated by setting bit CR3.SBIST = 1. If all the blocks in this data path operate correctly, the receive pattern detector locks onto the pattern. It then pulls INT Low and sets the following bits: • TSR.TQRSS = 1 • PSR.QRSS = 1 • PSR.BIST = 1 The QPD pin also indicates completion status of the test. Initiating the BIST forces QPD High. During the test, it remains High until the test finishes successfully, at which time it goes Low. The most reliable test will result when a separate TCLK and MCLK are applied and the Line Build-Out (LBO) is set to -22.5 dB (CR1.EC4:1 = 011x). 28 Datasheet Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications — LXT362 3.0 Register Definitions The LXT362 contains five read/write and three read-only registers that are accessible in Host mode via the serial I/O port. Table 7 lists the LXT362 register addresses. Only bits A6 through A1 of the address byte are valid (the address decoder ignores bits A7 and A0) while A0 functions as the read/ write (R/W) bit. Table 8 identifies the name of each register bit. Table 9 through Table 17 describe the function of the bits in each register. Note that upon power-up or reset, all registers are cleared to 0. Table 7. Register Addresses Register Address1, 2 A7 - A1 Name Abbr Control #1 CR1 x010000 Control #2 CR2 x010001 Control #3 CR3 x010010 Interrupt Clear ICR x010011 Transition Status TSR x010100 Performance Status PSR x010101 Equalizer Status ESR x010110 Control #4 CR4 x010111 1. x = don’t care 2. Address A0 is the read/write (R/W) bit. Table 8. Register and Bit Summary Register Name Bit Type 7 6 5 4 3 2 1 0 EC3 EC2 EC1 EALOOP ELLOOP ERLOOP Control #1 CR1 R/W JASEL1 JASEL0 ENCENB UNIENB EC4 Control #2 CR2 R/W RESET EPAT1 EPAT0 ETAOS ENLOOP 1 1 Control #3 CR3 R/W JA6HZ reserved SBIST EQZMON reserved ES64 ESCEN ESJAM Interrupt Clear ICR R/W CESU CESO CDFMO reserved2 CQRSS CAIS CNLOOP CLOS Transition Status TSR R ESUNF ESOVR TDFMO reserved1 TQRSS TAIS TNLOOP TLOS Performance Status PSR R reserved1 BIST DFMO reserved1 QRSS AIS NLOOP LOS Equalizer Status ESR R LATN7 LATN6 LATN5 LATN4 reserved1 reserved1 reserved1 reserved1 Control #4 CR4 R/W reserved1 reserved1 reserved1 reserved1 reserved1 LOS2048 reserved1 reserved1 1. In writable registers, bits labeled reserved should be set to 0 (except as in note 2 below) for normal operation and ignored in read only registers. 2. Write a 1 to this bit for normal operation. Datasheet 29 LXT362 — Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications Table 9. Control Register #1 Read/Write, Address (A7-A0) = x010000x Jitter Attenuator Bit Name 0 EC1 1 EC2 2 EC3 3 EC4 4 UNIENB 5 ENCENB 6 JASEL0 7 JASEL1 Function Sets T1 mode and equalizer (see Table 10 below for control codes). JASEL0 JASEL1 Position 1 0 Transmit 1 1 Receive 0 X Disabled 1 = Enable Unipolar I/O mode and allow insertion/detection of BPVs. 0 = Enable Bipolar I/O mode 1 = Enable B8ZS encoders/decoders and force Unipolar I/O mode. 0 = Disable B8ZS encoders/decoders Select jitter attenuation circuitry position in data path or disables the JA. See right hand section of table for codes. Ñ Table 10. Equalizer Control Input Settings EC4 EC3 EC2 EC11 Function 0 0 0 0 0 0 1 0 0 1 0 0 1 0 0 Pulse Cable Gain T1 Long Haul 0.0 dB pulse 100 Ω TP 36 dB T1 Long Haul -7.5 dB pulse 100 Ω TP 36 dB 0 T1 Long Haul -15.0 dB pulse 100 Ω TP 36 dB 1 0 T1 Long Haul -22.5 dB pulse 100 Ω TP 36 dB 0 0 1 T1 Long Haul 0.0 dB pulse 100 Ω TP 26 dB 0 1 1 T1 Long Haul -7.5 dB pulse 100 Ω TP 26 dB 0 1 0 1 T1 Long Haul -15.0 dB pulse 100 Ω TP 26 dB 0 1 1 1 T1 Long Haul -22.5 dB pulse 100 Ω TP 26 dB 1 0 0 1 D4 Short Haul 6 V pulse 100 Ω TP 12 dB 1 0 1 1 T1 Short Haul 0-133 ft / 0.6 dB 100 Ω TP 12 dB 1 1 0 0 T1 Short Haul 133-266 ft / 1.2 dB 100 Ω TP 12 dB 1 1 0 1 T1 Short Haul 266-399 ft / 1.8 dB 100 Ω TP 12 dB 1 1 1 0 T1 Short Haul 399-533 ft / 2.4 dB 100 Ω TP 12 dB 1 1 1 1 T1 Short Haul 533-655 ft / 3.0 dB 100 Ω TP 12 dB 1. EC1 sets the receive equalizer gain (EGL) for T1 long-haul operation. 30 Datasheet Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications — LXT362 Table 11. Control Register #2 Read/Write, Address (A7-A0) = x010001x Pattern Bit Name 0 ERLOOP1 1 ELLOOP1 2 EALOOP 3 ENLOOP 4 ETAOS 5 EPAT0 6 EPAT1 7 RESET Function EPAT0 EPAT1 0 0 Transmit TPOS/TNEG 0 1 Detect and transmit QRSS 1 0 In-band Loop Up Code 00001 1 1 In-band Loop Down Code 001 1 = Enable Remote loopback mode 0 = Disable Remote loopback mode 1 = Enable Local loopback mode 0 = Disable Local loopback mode 1 = Enable Analog loopback mode 0 = Disable Analog loopback mode 1 = Enable Network loopback detection 0 = Disable Network loopback detection Selected 1 = Enable Transmit All Ones 0 = Disable Transmit All Ones Selects internal data pattern transmission. See right hand section of table for codes. Ñ 1 = Reset device states and clear all registers. 0 = Reset complete. 1. To enable Dual loopback (DLOOP), set both ERLOOP = 1 and ELLOOP = 1. Table 12. Control Register #3 Read/Write, Address (A7-A0) = x010010x Bit Name 0 ESJAM 1 ESCEN 2 ES64 3 - 4 EQZMON 5 SBIST 6 - 7 JA6HZ Datasheet Description 1 = Disable jamming of Elastic Store read out clock (1/8 bit-time adjustment for over/underflow). 0 = Enable jamming of Elastic Store read out clock 1 = Center ES pointer for a difference of 16 or 32, depending on depth (clears automatically). 0 = Centering completed 1 = Set elastic store depth to 64 bits. 0 = Set elastic store depth to 32 bits. Reserved. Set to 0 for normal operation. 1 = Configure receiver equalizer for monitor mode application (DSX-1 monitor). 0 = Configure receiver equalizer for normal mode application 1 = Start Built-In Self Test. 0 = Built-In Self Test complete. Reserved. Set to 0 for normal operation. 1 = Set bandwidth of jitter attenuation loop to 6 Hz. 0 = Set bandwidth of jitter attenuation loop to 3 Hz. 31 LXT362 — Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications Table 13. Interrupt Clear Register Read/Write, Address (A7-A0) = x010011x Bit Name 0 CLOS 1 CNLOOP 2 CAIS 3 CQRSS 4 - 5 CDFMO 6 CESO 7 CESU Function1 1 = Clear/Mask Loss of Signal interrupt. 0 = Enable Loss of Signal interrupt. 1 = Clear/Mask Network loopback interrupt. 0 = Enable Network loopback interrupt. 1 = Clear/Mask Alarm Indication Signal interrupt. 0 = Enable Alarm Indication Signal interrupt. 1 = Clear/Mask Quasi-Random Signal Source interrupt. 0 = Enable Quasi-Random Signal Source interrupt. Reserved. Set to 1 for normal operation. 1 = Clear/Mask Driver Failure Monitor Open interrupt. 0 = Enable Driver Failure Monitor Open interrupt. 1 = Clear/Mask Elastic Store Overflow interrupt. 0 = Enable Elastic Store Overflow interrupt. 1 = Clear/Mask Elastic Store Underflow interrupt. 0 = Enable Elastic Store Underflow interrupt. 1. Leaving a 1 of in any of these bits masks the associated interrupt. Table 14. Transition Status Register Read Only, Address (A7-A0) = x010100x Bit Name 0 TLOS 1 TNLOOP 2 TAIS 3 TQRSS 4 - 5 TDFMO 6 ESOVR 7 ESUNF Function 1 = Loss of Signal (LOS) has changed since last clear LOS interrupt occurred. 0 = No change in status. 1 = NLOOP has changed since last clear NLOOP interrupt occurred. 0 = No change in status. 1 = AIS has changed since last clear AIS interrupt occurred. 0 = No change in status. 1 = QRSS has changed since last clear QRSS interrupt occurred1. 0 = No change in status. Reserved. Ignore. 1 = DFMO has changed since last clear DFMS interrupt occurred. 0 = No change in status. 1 = ES overflow status sticky bit2. 0 = No change in status. 1 = ES underflow status sticky bit2. 0 = No change in status. 1. A QRSS transition indicates receive QRSS pattern sync or loss. A simple error in QRSS pattern is not reported as a transition. 2. Tripping the overflow or underflow indicator in the ES sets the ESOVR/ESUNF status bit(s). Reading the Transition Status Register clears these bits. Setting CESO and CESU in the Interrupt Clear Register masks these interrupts. 32 Datasheet Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications — LXT362 Table 15. Performance Status Register Read Only, Address (A7-A0) = x010101x Bit Name 0 LOS 1 NLOOP 2 AIS 3 QRSS 4 - 5 DFMO 6 BIST 7 - Function 1 = Loss of Signal occurred. 0 = Loss of Signal did not occur. 1 = Network loopback active. 0 = Network loopback not active. 1 = Alarm Indicator Signal detected. 0 = Alarm Indicator Signal not detected. 1 = Quasi-Random Signal Source pattern detected. 0 = Quasi-Random Signal Source pattern not detected. Reserved. Ignore. 1 = Driver Failure Monitor Open detected. 0 = Driver Failure Monitor Open not detected. 1 = Built-In Self Test passed. 0 = Built-In Self Test did not pass (or was not run). Reserved. Ignore. Table 16. Equalizer Status Register Read Only, Address (A7-A0) = x010110x Bit Name Function 0 - Reserved. Ignore. 1 - Reserved. Ignore. 2 - Reserved. Ignore. 3 - Reserved. Ignore. 4 LATN4 5 LATN5 6 LATN6 7 LATN7 Receive Line Attenuation Indicators. Convert this binary output to a decimal number and multiply by 2.9 dB to determine the approximate cable attenuation as seen by the receiver. For example, if LATN7:4 = 1010 BIN (= 10 DEC), then the receiver is seeing a signal attenuated by approximately 29 dB (2.9 dB x 10) of cable. This approximation assumes that a 3 V pulse was transmitted. Table 17. Control Register #4 Read/Write, Address (A7-A0) = x010111x Bit Name 0 - Reserved. Set to 0 for normal operation, ignore when reading 1 - Reserved. Set to 0 for normal operation, ignore when reading 2 LOS2048 3 - Reserved. Set to 0 for normal operation, ignore when reading 4 - Reserved. Set to 0 for normal operation, ignore when reading 5 - Reserved. Set to 0 for normal operation, ignore when reading 6 - Reserved. Set to 0 for normal operation, ignore when reading 7 - Reserved. Set to 0 for normal operation, ignore when reading Datasheet Function 1 = Set LOS detection threshold to 2048 consecutive zeros. 0 = Set LOS detection threshold to 175 consecutive zeros. 33 LXT362 — Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications 4.0 Application Information 4.1 Transmit Return Loss Table 18 shows the transmit return loss values for T1 applications. Table 24 on page 39 specifies the receive return loss values. 4.2 Transformer Data Specifications for transformers are listed in Table 19. A list of transformers recommended for use with the LXT362 are specified in Table 20. 4.3 Application Circuits Figure 12 and Figure 13 show typical LXT362 applications for Hardware and Host modes of operation. Table 18. Transmit Return Loss Xfrmr/Rt R L (Ω ) 1:2 / 9.1 Ω 100 EC4:1 Refer to Table 10 1:1.151 / 0 Ω 100 1:22 / 0 Ω 100 1001 (D4 Mode) CL (pF) Return Loss (dB) 0 16 470 17 0 2 470 2 0 1 470 1 1. A 1:1.15 transmit transformer keeps the total transceiver power dissipation at a low level, a 0.47 µF DC blocking capacitor must be placed on TTIP or TRING. 2. A 0.47 µF DC blocking capacitor must be placed on TTIP or TRING. Table 19. Transformer Specifications for LXT362 Tx/Rx Frequency MHz Turns Ratio Primary Inductance µH (minimum) Leakage Inductance µH (max) Interwinding Capacitance pF (max) DCR Ω (maximum) Dielectric Breakdown V (minimum) 1.544 1:1.15 600 0.80 60 0.90 pri, 1.70 sec 1500 VRMS1 1.544 1:2 600 0.80 60 0.70 pri, 1.20 sec 1500 VRMS1 1.544 1:1 600 1.10 60 1.10 pri, 1.10 sec 1500 VRMS1 Tx Rx 1. Some applications require transformers with a center tap (Long-Haul applications with DC current in the T1 loop). 34 Datasheet Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications — LXT362 Table 20. Recommended Transformers for LXT362 Tx/Rx Turns Ratio Part Number Manufacturer PE-65388 Pulse Engineering 1:1.15 PE-65770 16Z5952 Vitec PE-65351 Pulse Engineering PE-65771 0553-5006-IC Bell-Fuse 66Z-1308 Fil-Mag 671-5832 Midcom Tx 1:2 67127370 Schott Corp 67130850 TD61-1205D HALO (combination Tx/Rx set) TG26-1205NI HALO (surface mount dual transformer 1CT:2CT & 1CT:2CT) TG48-1205NI HALO (surface mount dual transformer 1CT:2CT & 1:1) 16Z5946 Vitec FE 8006-155 Fil-Mag 671-5792 Midcom PE-64936 Pulse Engineering PE-65778 Rx 1:1 67130840 Schott Corp 67109510 TD61-1205D HALO (combination Tx/Rx set) 16Z5936 Vitec 16Z5934 4.3.1 Hardware Mode Circuit Figure 12 shows a typical LXT362 Hardware mode application. See Table 18 through Table 20 to select the transformers (T1 and T2), resistors (Rt and RL) and capacitor (CL) needed for this application. Note that if the application includes surge protection, such as a varistor or sidactor on the TTIP/ TRING lines, it may be necessary to reduce the value of the capacitor CL or eliminate it completely. Excessive capacitance at CL will distort the transmitted signals. Datasheet 35 LXT362 — Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications Figure 12. Typical Hardware Mode Application 1.544 MHz TAOS MCLK LLOOP RLOOP TCLK TCLK TPOS TPOS TNEG TNEG EC2 EC3 MODE T1 Framer EC4 TRSTE RCLK RCLK RPOS RPOS RNEG RNEG From CMOS Control Logic EC1 JASEL 0.47 µF2 LXT362 TTIP Rt1 CL 1 (0 TO 470 PF) TRING LOS T11 Rt1 RTIP NLOOP 100 Ω TVCC 68 µF 0.1 µF VCC RRING TGND 1:1 GND NOTES: 1. See Table 18 through Table 20 for CL, Rt, and transformer selection. 2. Optional for power savings. 4.3.2 Host Mode Circuit Figure 13 shows an application using the LXT362 in Host mode. See Table 18 through Table 20 to select the transformers (T1 and T2), resistors (Rt and RL) and capacitor (CL) needed for this application. 36 Datasheet Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications — LXT362 Note that if the application includes surge protection, such as a varistor or sidactor on the TTIP/ TRING lines, it may be necessary to reduce the value of the capacitor CL or eliminate it completely. Excessive capacitance at CL will distort the transmitted signals. Figure 13. Typical Host Mode Application VCC 22 kΩ 1.544 MHz MCLK INT CLKE TCLK TCLK TPOS TPOS TNEG T1 Framer +5 V CS TNEG SDO MODE TRSTE SDI RCLK RCLK RPOS RPOS RNEG RNEG Host SCLK 11 17 LXT362 0.47 µF2 T11 TTIP Rt1 CL1 (0 to 470 pF) LOS NLOOP TVCC Rt1 TRING RTIP VCC 0.1 µF 100 Ω 68 µF TGND RRING GND 1:1 NOTES: 1. See Table 18 through Table 20 for CL, Rt, and transformer selection. 2. Optional for power savings. Datasheet 37 LXT362 — Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications 5.0 Test Specifications Note: Table 21 through Table 28 and Figure 14 through Figure 20 represent the performance specifications of the LXT362 and are guaranteed by test except, where noted, by design. The minimum and maximum values listed in Table 23 through Table 28 are guaranteed over the recommended operating conditions specified in Table 22. Table 21. Absolute Maximum Ratings Parameter DC supply (reference to GND) Sym Min Max Unit VCC, TVCC – 6.0 V Input voltage, any pin 1 VIN GND - 0.3 V VCC + 0.3 V V Input current, any pin 2 IIN - 10 10 mA TSTG -65 150 °C Storage Temperature Caution: Exceeding these values may cause permanent damage. Caution: Functional operation under these conditions is not implied. Caution: Exposure to maximum rating conditions for extended periods may affect device reliability. 1. TVCC and VCC must not differ by more than 0.3 V during operation. TGND and GND must not differ by more than 0.3 V during operation. 2. Transient currents of up to 100 mA will not cause SCR latch-up. TTIP, TRING, TVCC, and TGND can withstand continuous currents of up to 100 mA. Table 22. Recommended Operating Conditions Sym Min Typ1 Max Unit DC Supply 2 VCC, TVCC 4.75 5.0 5.25 V Ambient Operating Temperature TA -40 – 85 °C PD – 450 540 mW 100% mark density PD – 300 360 mW 50% mark density PD – 350 425 mW 100% mark density PD – 250 300 mW 50% mark density PD – 400 485 mW 100% mark density PD – 275 330 mW 50% mark density Parameter Test Conditions Short Haul Total Power Dissipation3 Long Haul D4 1. Typical figures are at 25 °C and are for design aid only; not guaranteed and not subject to production testing. 2. TVCC and VCC must not differ by more than 0.3 V. 3. Power dissipation while driving 100 Ω load over operating range. Includes power dissipation on device and load. Digital levels are within 10% of the supply rails and digital outputs driving a 50 pF capacity load, RL=9.1, T1=1:2. 38 Datasheet Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications — LXT362 Table 23. Digital Characteristics Parameter Sym Min Typ High level input voltage 1,2 (pins 1-4, 17, 23-25)4 VIH 2.0 – – V Low level input voltage 1,2 (pins 1-4, 17, 23-25)4 VIL – – 0.8 V VOH 2.4 – – V IOUT = 400 µA 0.4 V IOUT = 1.6 mA High level output voltage 1,2 (pins 6-8, 10, 12, 23, 25)4 1,2 4 Unit VOL – – 4 VIH 3.5 – – V Midrange input voltage 3 (pins 5, 9, 11, 26-28)4 VIM 2.3 – 2.7 V VIL – – 0.8 V VIL – – 1.5 V ILL 0 – ±50 µA Three-state leakage current (all outputs) I3L 0 – ±10 µA TTIP/TRING leakage current (pins 13, 16)4 ITR – – ±1.2 mA Low level output voltage (pins 6-8, 10, 12, 23, 25) Max 3 High level input voltage (pins 5, 9, 11, 26-28) Host mode Low level input voltage 3 (pins 5, 9, 11, 26-28)4 Hardware mode Input leakage current 1 1. 2. 3. 4. Test Conditions in Idle and Power Down Functionality of pins 23 and 25 depend on mode. See Host mode and Hardware mode description. Output drivers will output CMOS logic levels into CMOS loads. As an alternative to supplying 2.3 - 2.7 V (Midrange logic level) to these pins, they may be left open. Referenced pin numbers are for the PLCC package. Refer to Figure 2 on page 8 for the corresponding QFP pins. Table 24. Analog Characteristics Parameter Recommended output load on TTIP/TRING AMI Output Pulse Amplitudes DSX-1, DS1 10 Hz - 8 kHz Jitter added by the transmitter2 3 8 kHz - 40 kHz 3 Max Unit 50 – 200 Ω 2.4 3.0 3.6 V – – 0.02 UI Test Conditions RL = 100 Ω – – 0.025 UI – – 0.025 UI Broad Band – – 0.05 UI 0 – 26 dB 0 – 36 dB 0 – 13.6 dB 160 175 190 – 0.4 – – UI 138 – – UI 0 dB line AT&T Pub 62411 – 3 – Hz selectable in data port (Long-Haul) Mode 2 (EC1 = 0) (Long-Haul) Mode 3 (EC4 = 1) (Short-Haul) Allowable consecutive zeros before LOS 10 kHz - 100 kHz Input jitter tolerance 1 Hz 3 Jitter attenuation curve corner frequency 4 1. 2. 3. 4. Typ1 10 Hz - 40 kHz3 Mode 1 (EC1 = 1) Receiver sensitivity @ 772 kHz Min See Table 10 for Gain Setting Typical figures are at 25 °C and are for design aid only; not guaranteed and not subject to production testing. Input signal to TCLK is jitter-free. The Jitter Attenuator is in the receive path or disabled. Guaranteed by characterization; not subject to production testing. Circuit attenuates jitter at 20 dB/decade above the corner frequency. Datasheet 39 LXT362 — Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications Figure 14. 1.544 MHz T1 Pulse (DS1 and DSX-1) (See Table 25) 1.5 1.5 Normalized Amplitude 1.0 1.0 0.5 0.5 0.5 -0.5 0.0 1.0 Normalized Amplitude 1.5 0.5 -0.5 0.0 Time 1.0 1.5 Time (in Unit Intervals) (in Unit Intervals) -0.5 -0.5 Table 25. 1.544 MHz T1 Pulse Mask Corner Point Specifications DS1 Template (per ANSI T1. 403-1995) Minimum Curve DSX-1 Template (per ANSI T1. 102-1993) Maximum Curve Minimum Curve Maximum Curve Time (UI) Amplitude Time (UI) Amplitude Time (UI) Amplitude Time (UI) Amplitude -0.77 -0.05 -0.77 0.05 -0.77 -0.05 -0.77 0.05 -0.23 -0.05 -0.39 0.05 -0.23 -0.05 -0.39 0.05 -0.23 0.50 -0.27 0.80 -0.23 0.50 -0.27 0.80 -0.15 0.90 -0.27 1.20 -0.15 0.95 -0.27 1.15 0.0 0.95 -0.12 1.20 0.0 0.95 -0.12 1.15 0.15 0.90 0.0 1.05 0.15 0.90 0.0 1.05 0.23 0.50 0.27 1.05 0.23 0.50 0.27 1.05 0.23 -0.45 0.34 -0.05 0.23 -0.45 0.35 -0.07 0.46 -0.45 0.77 0.05 0.46 -0.45 0.93 0.05 0.61 -0.26 1.16 0.05 0.66 -0.20 1.16 0.05 0.93 -0.05 0.93 -0.05 1.16 -0.05 1.16 -0.05 Table 26. Master and Transmit Clock Timing Characteristics (See Figure 15) Sym Min Typ1 Max Unit Master clock frequency MCLK – 1.544 – MHz Master clock tolerance MCLKt – ±50 – ppm Master clock duty cycle MCLKd 40 – 60 % Transmit clock frequency TCLK – 1.544 – MHz Transmit clock tolerance TCLKt – – ±100 ppm Parameter Notes must be supplied 1. Typical figures are at 25 °C and are for design aid only; not guaranteed and not subject to production testing. 40 Datasheet Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications — LXT362 Table 26. Master and Transmit Clock Timing Characteristics (See Figure 15) Parameter Transmit clock duty cycle Sym Min Typ1 Max Unit TCLKd 10 – 90 % TPOS/TNEG to TCLK setup time tSUT 50 – – ns TCLK to TPOS/TNEG hold time tHT 50 – – ns Notes 1. Typical figures are at 25 °C and are for design aid only; not guaranteed and not subject to production testing. Figure 15. Transmit Clock Timing Table 27. Receive Timing Characteristics (See Figure 16) Parameter Receive clock duty cycle 2, 3 2, 3 Sym Min Typ1 Max Unit RLCKd 40 50 60 % tPW – 648 – ns tPWH – 324 – ns tPWL 260 324 388 ns RPOS/RNEG to RCLK rising time tSUR – 274 – ns RCLK rising to RPOS/RNEG hold time tHR – 274 – ns Receive clock pulse width Receive clock pulse width high Receive clock pulse width low 1,3 1. Typical figures are at 25 °C and are for design aid only; not guaranteed and not subject to production testing. 2. RCLK duty cycle widths will vary according to extent of received pulse jitter displacement. Max and Min RCLK duty cycles are for worst case jitter conditions. 3. Worst case conditions guaranteed by design only. Datasheet 41 LXT362 — Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications Figure 16. Receive Clock Timing , , Table 28. Serial I/O Timing Characteristics (See Figure 17 and Figure 18) Sym Min Typ1 Max Unit Rise/fall time—any digital output tRF – – 100 ns SDI to SCLK setup time tDC 50 – – ns SCLK to SDI hold time Parameter tCDH 50 – – ns SCLK low time tCL 240 – – ns SCLK high time tCH 240 – – ns tR, tF – – 50 ns SCLK rise and fall time CS falling edge to SCLK rising edge tCC 50 – – ns Last SCLK edge to CS rising edge tCCH 50 – – ns CS inactive time tCWH 250 – – ns SCLK to SDO valid time tCDV – – 200 ns SCLK falling edge or CS rising edge to SDO high-Z tCDZ – 100 – ns Parameter Load 1.6 mA, 50 pF 1. Typical figures are at 25 °C and are for design aid only; not guaranteed and not subject to production testing. 42 Datasheet Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications — LXT362 Figure 17. Serial Data Input Timing Diagram Figure 18. Serial Data Output Timing Diagram CLKE = 0 1 2 3 4 5 6 7 8 9 10 11 1 2 12 13 14 15 5 6 16 SCLK CS tCCH tCDZ SDO 0 4 3 7 CLKE = 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 SCLK CS SDO Datasheet 0 1 2 3 4 5 tCDZ 6 tCCH 7 43 LXT362 — Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications Figure 19. Typical T1 Jitter Tolerance at 36 dB 1000 UI Jitter 500 UI @ 10 Hz LXT362 Device Typical Jitter Tolerance Loop Mode 138 UI 100 UI Pub 62411 28 UI Dec 1990 10 UI 0.6 UI @ 10 kHz 1 UI 0.4 UI .1 UI 1 Hz 10 Hz 100 Hz 1 kHz 10 kHz 100 kHz Frequency 44 Datasheet Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications — LXT362 Figure 20. T1 Jitter Attenuation Datasheet 45 LXT362 — Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications 6.0 Mechanical Specifications Figure 21. Plastic Leaded Chip Carrier Package Specifications 28-Pin PLCC • Part Number LXT362PE • Extended Temperature Range (-40 °C to 85 °C) CL C B D1 D D A2 A A1 F Inches Millimeters Dim Min Max Min Max A 0.165 0.180 4.191 4.572 A1 0.090 0.120 2.286 3.048 A2 0.062 0.083 1.575 1 2.108 1 B .050 BSC (nominal) 1.27 BSC (nominal) C 0.026 0.032 0.660 0.813 D 0.485 0.495 12.319 12.573 D1 0.450 0.456 11.430 11.582 F 0.013 0.021 0.330 0.533 1. BSC—Basic Spacing between Centers. 46 Datasheet Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications — LXT362 Figure 22. Plastic Quad Flat Package Specifications 44-Pin PQFP • Part Number LXT362QE • Extended Temperature Range (-40 °C to 85 °C) D D1 D3 e E1 E3 E θ3 L1 A2 A θ A1 θ3 B L Inches Millimeters Dim Min Max Min Max A – 0.096 – 2.45 A1 0.010 – 0.25 – A2 0.077 0.083 1.95 2.10 B 0.012 0.018 0.30 0.45 D 0.510 0.530 12.95 13.45 D1 0.390 0.398 9.90 1 10.10 1 0.315 BSC (nominal) 8.00 BSC (nominal) E 0.510 0.530 12.95 E1 0.390 0.398 9.90 D3 13.45 10.10 E3 1 0.315 BSC (nominal) 8.00 BSC (nominal) e 1 0.80 BSC1 (nominal) 0.031 BSC (nominal) L 0.029 L1 0.063 BSC1 (nominal) 0.041 1 0.73 1.03 1.60 BSC1 (nominal) q3 5° 16° 5° 16° q 0° 7° 0° 7° 1. BSC—Basic Spacing between Centers. Datasheet 47 LXT362 — Integrated T1 LH/SH Transceiver for DS1/DSX-1 or PRI Applications Figure 23. Low-Profile Quad Flat Package Specifications 44-Pin LQFP • Part Number LXT362LE • Extended Temperature Range (-40 °C to 85 °C) D NOTE: All dimensions in millimeters. D/2 b E/2 e E1/2 e/2 E1 E M 0 DEG. MIN. A2 0.08 / 0.20 R. D1/2 A1 D1 0.08 R. MIN. A L 0.20 MIN. 1.00 REF. 0 - 7 DEG. Millimeters Dimension1 Minimum Nominal Maximum A - - 1.60 A1 0.05 0.10 0.15 A2 1.35 1.40 1.45 b 0.30 0.37 0.45 D 12.00 (basic spacing between centers) D1 10.00 (basic spacing between centers) E 12.00 (basic spacing between centers) E1 10.00 (basic spacing between centers) e 0.80 (basic spacing between centers) L 0.45 0.60 0.75 M 0.15 - - 1. See JEDEC Publication for additional specifications. 48 Datasheet