® AFE AFE2124 212 4 For most current data sheet and other product information, visit www.burr-brown.com Dual HDSL/SDSL ANALOG FRONT END FEATURES DESCRIPTION ● SERIAL DIGITAL INTERFACE ● 48-LEAD SSOP PACKAGE Burr-Brown’s dual Analog Front End chip greatly reduces the size and cost of a DSL (Digital Subscriber Line) system by providing all of the active analog circuitry needed to connect two digital signal processors to external compromise hybrids and line transformers. The AFE2124 is optimized for HDSL (High bit rate DSL) and for SDSL (symmetrical DSL) applications. Because the transmit and receive filter responses automatically change with clock frequency, the AFE2124 is particularly suitable for multiple rate DSL systems. The device operates over a wide range of data rates from 64kbps to 1168kbps. Functionally, each half of this unit consists of a transmit and a receive section. The transmit section generates analog signals from 2-bit digital symbol data and filters the analog signals to create 2B1Q symbols. The onboard differential line driver provides a 13.5dBm signal to the telephone line. The receive section filters and digitizes the symbol data received on the telephone line. This IC operates on a single 5V supply. The digital circuitry in the unit can be connected to a supply from 3.3V to 5V. It is housed in a 48-lead SSOP package. ● E1, T1 AND SDSL OPERATION ● 64kbps TO 1168kbps OPERATION ● SCALEABLE DATA RATE ● 250mW POWER DISSIPATION PER CHANNEL ● TWO COMPLETE HDSL ANALOG INTERFACES ● +5V POWER (5V or 3.3V Digital) txLINE Pulse Former txLINE Line Driver tx and rx Interface Lines tx and rx Control Registers Difference Amplifier Decimation Filter rxHYB rxHYB ∆Σ Modulator rxLINE Programmable Gain Amp 1/2 of AFE2124 rxLINE Patents Pending International Airport Industrial Park • Mailing Address: PO Box 11400, Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706 • Tel: (520) 746-1111 Twx: 910-952-1111 • Internet: http://www.burr-brown.com/ • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132 © 1999 Burr-Brown Corporation SBWS010 PDS-1538A Printed in U.S.A. April, 1999 SPECIFICATIONS Typical at 25°C, AVDD = +5V, DVDD = +3.3V, and txBaudCLK = 584kHz (E1 rate), unless otherwise noted.Specifications apply to each channel of the AFE2124. AFE2124E PARAMETER COMMENTS MIN RESOLUTION TYP MAX 14 RECEIVE CHANNEL Number of Inputs Input Voltage Range Common-Mode Voltage Input Impedance All Inputs Input Capacitance Input Gain Matching Programmable Gain Settling Time Gain + Offset Error Output Data Coding Output Symbol Rate, rxSYNC(3) Output Bit Rate, rxSYNC(3) TRANSMIT CHANNEL Transmit Clock Rate, txBaudCLK T1 Transmit –3dB Point T1 Rate Power(4, 5) E1 Transmit –3dB Point E1 Transmit Power(4, 5) Pulse Output Common-Mode Voltage, VCM Output Resistance(6) TRANSCEIVER PERFORMANCE Uncancelled Echo(5) DIGITAL INTERFACE(6) Logic Levels VIH VIL VOH VOL trx1 Interface POWER Analog Power Supply Voltage Analog Power Supply Voltage Digital Power Supply Voltage Digital Power Supply Voltage Power Dissipation(4, 5) Power Dissipation(4, 5) Power Supply Rejection Ratio (PSRR) Differential Balanced Differential(1) Line Input vs Hybrid Input 0dB, 3dB, 6dB, 9dB and 12dB For Any Change in Gain or txBaud CLK Tested at Each Gain Range Two’s Complement Bits 2 ±3.0 AVDD/2 See Typical Performance Curves 10 ±2 0 +12 6 5 32 64 Symbol Rate ETSI RTR/TM - Compliant txBoost = 0 ETSI RTR/TM - Compliant txBoost = 0 DC to 1MHz 32 13 TEMPERATURE RANGE Operating(6) kHz kHz dBm kHz dBm 13 14 See Typical Performance Curves AVDD /2 1 dB dB dB dB dB dB DVDD + 0.3 +0.8 V V V V ns 5 4.75 5.25 V V V V mW mW dB +85 °C 5.25 3.3 3.15 250 300 55 –40 V Ω –68.5 –68.5 –71 –73.5 –75.5 –77.5 +0.4 14 9 Specification Operating Range Specification Operating Range AVDD = 5V, DVDD = 3.3V, AVDD = DVDD = 5V 584 14 DVDD – 1 –0.3 DVDD – 0.5 pF % dB Symbol Periods %FSR(2) kHz kbits/sec 292 –71 –71 –74 –76 –78 –80 V V 584 1168 196 rxGAIN = 0dB, Loopback Enabled rxGAIN = 0dB, Loopback Disabled rxGAIN = 3dB, Loopback Disabled rxGAIN = 6dB, Loopback Disabled rxGAIN = 9dB, Loopback Disabled rxGAIN = 12dB, Loopback Disabled |IIH| < 10µA |IIL| < 10µA IOH = –20µA IOL = 20µA UNITS NOTES: (1) With a balanced differential signal, the positive input is 180° out of phase with the negative input, therefore, the actual voltage swing about the commonmode voltage on each pin is ±1.5V to achieve a total input range of ±3.0V or 6Vp-p. (2) FSR is Full-Scale Range. (3) The output data is available at twice the symbol rate. (4) With a pseudo-random equiprobable sequence of HDSL pulses; 13.5dBm applied to the transformer (16.5dBm output from txLINEP and txLINEN). (5) See the Discussion of Specifications section of this data sheet for more information. (6) Guaranteed by design and characterization. The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN assumes no responsibility for the use of this information, and all use of such information shall be entirely at the user’s own risk. Prices and specifications are subject to change without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not authorize or warrant any BURR-BROWN product for use in life support devices and/or systems. ® AFE2124 2 ELECTROSTATIC DISCHARGE SENSITIVITY ABSOLUTE MAXIMUM RATINGS Analog Inputs: Current .............................................. ±100mA, Momentary ±10mA, Continuous Voltage .................................. AGND –0.3V to AVDD +0.3V Analog Outputs Short Circuit to Ground (+25°C) ..................... Continuous AVDD to AGND ......................................................................... –0.3V to 6V DVDD to DGND ......................................................................... –0.3V to 6V Digital Input Voltage to DGND .................................. –0.3V to DVDD +0.3V Digital Output Voltage to DGND ............................... –0.3V to DVDD +0.3V AGND, DGND, Differential Voltage .................................................... 0.3V Junction Temperature (TJ) ............................................................. +150°C Storage Temperature Range .......................................... –40°C to +125°C Lead Temperature (soldering, 3s) .................................................. +260°C Power Dissipation .......................................................................... 700mW This integrated circuit can be damaged by ESD. Burr-Brown recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. PACKAGE/ORDERING INFORMATION PRODUCT PACKAGE PACKAGE DRAWING NUMBER(1) SPECIFIED TEMPERATURE RANGE PACKAGE MARKING ORDERING NUMBER(2) TRANSPORT MEDIA AFE2124E SSOP-48 333 –40°C to +85°C AFE2124E " " " " " AFE2124E AFE2124E/1K Rails Tape and Reel NOTES: (1) For detailed drawing and dimension table, please see end of data sheet, or Appendix C of Burr-Brown IC Data Book. (2) Models with a slash (/) are available only in Tape and Reel in the quantities indicated (e.g., /1K indicates 1000 devices per reel). Ordering 1000 pieces of “AFE2124E/1K” will get a single 1000piece Tape and Reel. For detailed Tape and Reel mechanical information, refer to Appendix B of Burr-Brown IC Data Book. BLOCK DIAGRAM 1/2 AFE2124 txLINE+ Pulse Former Filter Output Buffer txLINE– REFP txbaudCLK tx48xCLK Voltage Reference Transmit Control VCM REFN Data In rxbaudCLK rx48xCLK Receive Control rxLINE+ Data Out ∆Σ Modulator rxLINE– rxHYB+ rxHYB– Decimation Filter ® 3 AFE2124 PIN CONFIGURATION PIN DESCRIPTIONS Top View SSOP PIN # TYPE NAME DESCRIPTION CHANNEL A 1 Output Data OutA Output Data Word 2 Input rx48xCLKA Receive Clock at 48x Baud Clock (23.032MHz for E1) Receive Baud Clock (584kHz for E1) Data OutA 1 48 Data OutB 3 Input rxbaudCLKA rx48xCLKA 2 47 rx48xCLKB 4 Input Data InA rxbaudCLKA 3 46 rxbaudCLKB 5 Input tx48xCLKA Transmit Clock (584kHz for E1) 6 Input txbaudCLKA Transmit Baud Clock at 48x Baud Clock (584kHz for E1) Input Data Word Data InA 4 45 Data InB tx48xCLKA 5 44 tx48xCLKB 7 Power DVDD Digital Supply (+3.3V to +5V) txbaudCLKA 6 43 txbaudCLKB 8 Ground DGND Digital Ground DVDD 7 42 DVDD Analog Ground 9 Ground AGND 10 Output txLINE+A 11 Power AVDD 8 41 DGND AGND 9 40 AGND 12 Output txLINE–A txLINE+A 10 39 txLINE+B 13 Ground AGND 14 Power AVDD 15 Output REFNA DGND AVDD 11 txLINE–A 12 AGND 13 AVDD REFNA 38 AVDD Transmit Line Driver Output, Positive Analog Supply (+5V) Transmit Line Driver Output, Negative Analog Ground Analog Supply (+5V) Negative Reference Output 37 txLINE–B 16 Output VCMA 36 AGND 17 Output REFPA Positive Reference Output 14 35 AVDD 18 Ground AGND Analog Ground 15 34 REFNB 19 Ground AGND Analog Ground 20 Input rxLINE+A 21 Input rxLINE–A Negative Line Input Input rxHYB+A Positive Input from Hybrid Network Negative Input from Hybrid Network AFE2124 Channel A Channel B Common-Mode Voltage (buffered) Positive Line Input VCMA 16 33 VCMB REFPA 17 32 REFPB 22 AGND 18 31 AGND 23 Input rxHYB–A AGND 24 Power AVDD Analog Supply (+5V) 25 Power AVDD Analog Supply (+5V) AGND 19 30 rxLINE+A 20 29 rxLINE+B rxLINE–A 21 28 rxLINE–B 26 Input rxHYB–B Negative Input from Hybrid Network rxHYB+A 22 27 rxHYB+B 27 Input rxHYB+B Positive Input from Hybrid Network rxHYB–A 23 26 rxHYB–B 28 Input rxLINE–B Negative Line Input 29 Input rxLINE+B Postiive Line Input 30 Ground AGND Analog Ground 31 Ground AGND Analog Ground 32 Output REFPB 33 Output VCMB AVDD 24 25 CHANNEL B AVDD ® AFE2124 4 Positive Reference Output Common-Mode Voltage (buffered) 34 Output REFNB 35 Power AVDD Negative Reference Output Analog Supply (+5V) 36 Ground AGND Analog Ground 37 Output txLINE–B 38 Power AVDD 39 Output txLINE+B 40 Ground AGND Analog Ground 41 Ground DGND Digital Ground 42 Power DVDD Digital Supply (+3.3V to +5V) 43 Input txbaudCLKB Transmit Baud Clock (584kHz for E1) 44 Input tx48xCLKB Transmit Clock at 48x Baud Clock (28.032MHz for E1) 45 Input Data InB 46 Input rxbaudCLKB Receive Baud Clock (584kHz for E1) 47 Input rx48xCLKB Receive Clock at 48x Baud Clock (28.032MHz for E1) 48 Output Data OutB Output Data Word Transmit LIne Driver Output, Negative Analog Supply (+5V) Transmit Line Driver Output, Positive Input Data Word TYPICAL PERFORMANCE CURVES At Output of HDSL Pulse Transformer The curves shown below are measured at the line output of the HDSL transformer. Typical at 25°C, AVDD+ = +5V, DVDD+ = +3.3V, txBaudCLK = 584kHz (E1), unless otherwise specified. POWER SPECTRAL DENSITY LIMIT Power Spectral Density (dBm/Hz) –20 –38dBm/Hz for T1 –40 –80dB/decade T1 –40dBm/Hz for E1 E1 –60 –80 196kHz 292kHz –118dBm/Hz for T1 –120dBm/Hz for E1 –100 –120 1K 10K 1M 100K 10M Frequency (Hz) CURVE 1. Upper Bound of Power Spectral Density Measured at Output of HDSL Transformer. 0.4T 0.4T B = 1.07 C = 1.00 D = 0.93 1.25T A = 0.01 E = 0.03 F = –0.01 –1.2T –0.6T A = 0.01 H = –0.05 14T G = –0.16 0.5T F = –0.01 50T CURVE 2. Transmitted Pulse Template Measured at HDSL Transformer Output. INPUT IMPEDANCE vs BIT RATE Input Impedance (kΩ) 200 150 100 T1 = 784kbps, 32kΩ 50 E1 = 1168kbps, 21kΩ 0 100 300 500 700 900 1100 1300 Bit Rate (kbps) CURVE 3. Input Impedance of rxLINE and rxHYB. ® 5 AFE2124 THEORY OF OPERATION oversampling ratio, produces a 14-bit output at rates up to 584kHz (1.168Mbps). The AFE2124 has two HDSL Analog Front End (AFE) circuits on chip (channel A and channel B). Each AFE is functionally equivalent to an AFE1124. Each AFE consists of a transmit and a receive channel which interfaces to a HDSL DSP through a six-wire serial interface—three wires for the transmit channel and three wires for the receive channel. It interfaces to the HDSL telephone line transformer and external compromise hybrid through transmit and receive analog connections. The receive channel operates by summing the two differential inputs, one from the line (rxLINE) and the other from the compromise hybrid (rxHYB). The connection of these two inputs so that the hybrid signal is subtracted from the line signal is described in the paragraph titled “Echo Cancellation in the AFE.” The equivalent gain for each input in the difference amp is one. The resulting signal then passes to a programmable gain amplifier which can be set for gains of 0dB through +12dB. Following the PGA, the ADC converts the signal to a 14-bit digital word. The serial interface consists of three wires for transmit and three wires for receive. The three-wire transmit interface is transmit baud rate clock, transmit 48x oversampling clock and Data Out. The three-wire receive interface is receive baud rate clock, receive 48x oversampling clock and Data In. The transmit and receive clocks are supplied to the AFE2124 from the DSP and are completely independent. The transmit channel consists of a switched-capacitor pulse forming network followed by a differential line driver. The pulse-forming network receives 2-bit digital symbol data and generates a filtered 2B1Q analog output waveform. The differential line driver uses a composite output stage combining class B operation (for high efficiency driving large signals) with class AB operation (to minimize crossover distortion). The receive channel is designed around a fourth-order delta sigma analog-to-digital converter. It includes a difference amplifier designed to be used with an external compromise hybrid for first-order analog echo cancellation. A programmable gain amplifier with gains of 0dB to +12dB is also included. The delta sigma modulator, operating at a 24x DIGITAL DATA INTERFACE Data is received by the AFE2124 from the DSP on the Data In line. Data is transmitted from the AFE2124 to the DSP on the Data Out line. The following paragraphs describe the timing of these signals and data structure. rxbaudCLK rx48xCLK Data Out HDSL DSP 1/2 AFE2124 txbaudCLK tx48xCLK Data In FIGURE 1. DSP Interface. 4ns 4ns txbaudCLK from DSP A B 4ns tx48xCLK from DSP 4ns 48 Data In from DSP 1 2 3 4 MSB Bit 15 15 16 LSB Bit 0 47 48 1 MSB Bit 15 Transmit Timing Notes: (1) A baud period consists of 48 periods of the tx48xCLK. (2) The falling edge of the txbaudCLK can occur anywhere in area A. The rising edge can occur anywhere in area B. However, neither edge of the txbaudCLK can occur within 4ns (on either side) of any rising edge of tx48xCLK. (3) The AFE2124 reads Data In on the rising edge of the tx48xCLK. Data In must be stable at least 4ns before the rising edge of tx48xCLK and it must remain stable at least 4ns after the rising edge of tx48xCLK. (4) Symbol data is transferred to the transmit pulse former after the LSB is read. The output analog symbol data reaches the peak of the symbol approximately 24 tx48xCLK periods later. FIGURE 2. Transmit Timing Diagram. ® AFE2124 6 Data is transmitted and received in synchronization with the 48x transmit and receive clocks (tx48xCLK and rx48xCLK). There are 48-bit times in each baud period. Data In is received in the first 16 bits of each baud period. The remaining 32-bit periods are not used for Data In. Data Out is transmitted during the first 16 bits of the baud period. A second interpolated value is transmitted in subsequent bits of the baud period. and other control bits, as described below. The data should be clocked out of the DSP on the falling edge and should be valid on the rising edge of the tx48xCLK. The AFE2124 reads Data In on the rising edge of the tx48xCLK. The bits are defined in Table I. Data In is read by the AFE2124 during the first 16 bits periods of each baud period. Only the first 8 bits are used in the AFE2124. The second 8 bits are reserved for use in the future products. The remaining 32 bits periods of the baud period are not used for Data In. txbaudCLK: The transmit data baud rate, generated by the DSP. It is 392kHz for T1 or 584kHz for E1. It may vary from 32kHz (64kbps) to 584kHz (1.168Mbps). Data In Bits tx48xCLK: The transmit pulse former oversampling sampling clock, generated by the DSP. It is 48x the transmit symbol rate or 28.032MHz for 584kHz symbol rate. This clock should run continuously. tx Enable Signal—This bit controls the tx Symbol definition bits. If this bit is 0, only a 0 symbol is transmitted regardless of the state of the tx Symbol definition bits. If this bit is 1, the tx Symbol definition bits determine the output symbol. Data In: This is a 16-bit output data word sent from the DSP to the AFE. The sixteen bits include tx symbol information tx Symbol Definition—These two bits determine the output 2B1Q symbol transmitted. MSB 1 LSB 2 3 1 1 8 Reserved tx Boost Loopback rx Gain tx Symbol tx Enable FIGURE 3. Data In Word. 4ns rxbaudCLK from DSP 4ns A B 4ns rx48xCLK from DSP Data Out from AFE2124 4ns 48 1 14 MSB Bit 15 15 16 17 23 24 LSB Bit 0 25 26 MSB Bit 15 39 40 47 48 1 MSB Bit 15 LSB Bit 0 trx1 Data 1 Interdata 8 Bits Data 1a Interdata 8 Bits Data 2 Receive Timing Notes: (1) A baud period consists of 48 periods of the tx48xCLK. (2) The falling edge of the rxbaudCLK can occur anywhere in area A. The rising edge can occur anywhere in area B. However, neither edge of the rxbaudCLK can occur within 4ns (on either side) of any rising edge of rx48xCLK. (3) For all data bits after the MSB of Data 1, the AFE2124 transfers Data Out on the falling edge of the rx48xCLK. The time from the falling edge of rx48xCLK until Data Out is stable is trx1. trx1 min max 9ns 14ns (4) The AFE2124 transfers the MSB of Data 1 on the falling edge of rxbaudCLK. If the falling edge of rxbaudCLK is synchronized with the falling edge of rx48xCLK, all of the Data Out bits will be the same width. In any case, the time from the falling edge of rxbaudCLK until the MSB of Data 1 is stable is trx1. FIGURE 4. Receive Timing Diagram. ® 7 AFE2124 BIT DESCRIPTION BIT STATE OUTPUT STATE 15 (MSB) tx Enable Signal 0 1 AFE Transmits a 0 Symbol AFE Transmits HDSL Symbol as defined by bits 14 and 13 00 –3 Transmit Symbol 01 11 10 –1 Transmit Symbol +1 Transmit Symbol +3 Transmit Symbol 000 001 010 011 100 101 110 111 rx gain in AFE 0dB rx gain in AFE 3dB rx gain in AFE 6dB rx gain in AFE 9dB rx gain in AFE 12dB rx gain in AFE Reserved rx gain in AFE Reserved rx gain in AFE Reserved 14 and 13 12 - 10 tx Symbol Definition rx Gain Settings 9 Loopback Control 1 0 Loopback Mode Normal Operation 8 tx Boost 0 1 Normal Transmit Power +0.5dB Transmit Power Boost 7-0 SPARE DATA OUT PER SYMBOL PERIOD DATA BITS Data 1 16 Interdata Bits 8 Data 1a 16 Interdata bits 8 Total Bits/Symbol Period 48 MSB LSB 14 2 Reserved A/D Converter Data NA FIGURE 5. Data Out Word. TABLE I. Data In. ANALOG-TO-DIGITAL CONVERTER DATA The A/D converter data from the receive channel is coded in Binary Two’s Complement. Rx Gain Settings—These bits set the gain of the receive channel programmable gain amplifier. Loopback Control—This bit controls the operation of loopback. When enabled (logic 1), the rxLINE+ and rxLINE– inputs are disconnected from the AFE. The rxHYB+ and rxHYB– inputs remain connected. When disabled, the rxLINE+ and rxLINE– inputs are connected. ANALOG INPUT MSB Positive Full Scale txBoost—This bit controls the addition of 0.5dB additional power to the output line driver. rxbaudCLK: This is the receive data baud rate (symbol clock), generated by the DSP. It is 392kHz for T1 or 584kHz for E1. It can vary from 32kHz (64kbps) to 584kHz (1.168Mbps). LSB 01111111111111 Mid Scale 00000000000000 Negative Full Scale 10000000000000 ECHO CANCELLATION IN THE AFE The rxHYB input is subtracted from the rxLINE input for first order echo cancellation. For correct operation, be certain that the rxLINE input is connected to the same polarity signal at the transformer (+ to + and – to –) while the rxHYB input is connected to opposite polarity through the compromise hybrid (– to + and + to –) as shown in Figure 6. rx48xCLK: This is the A/D converter oversampling clock, generated by the DSP. It is 48x the receive symbol rate or 28.032MHz for 584kHz symbol rate. This clock should run continuously. Data Out: This is the 14-bit A/D converter output data (+2 spare bits) sent from the AFE to the DSP. The 14 bits from the A/D Converter will be the upper bits of the 16-bit word (bits 15-2). The spare bits (1 and 0) will be always be low. Eight additional (interdata) bits follow, which are always high. The data is clocked out on the falling edge of rx48xCLK. The bandwidth of the A/D converter decimation filter is equal to one-half of the symbol rate. The nominal output rate of the A/D converter is one conversion per symbol period. For more flexible post processing, there is a second true A/D conversion available in each symbol period. In Figure 4, the first conversion is shown as Data 1 and the second conversion is shown as Data 1a. It is suggested that rxbaudCLK is used with the rx48xCLK to read Data 1 while Data 1a is ignored. However, either or both outputs may be used for more flexible post-processing. SCALEABLE TIMING The AFE2124 scales operation with the clock frequency. All internal filters and the pulse former change frequency with the clock speed so that the unit can be used at different frequencies just by changing the clock speed. For the receive channel, the digital filtering of the delta sigma converter scales directly with the clock speed. The bandwidth of the converter’s decimation filter is always onehalf of the symbol rate. The only receive channel issue in changing baud rate is the passive single pole anti-alias filter (see the “rxHYB and rxLINE Input Anti-Aliasing Filters” section). For systems implementing a broad range of speeds, selectable cutoff frequencies for the passive anti-alias filter should be used. ® AFE2124 A/D CONVERTER DATA 8 0.1µF REFP VCM 0.1µF 0.1µF REFN 1:2 Transformer 13Ω Tip txLINE+ 0.01µF 13Ω txLINE– Ring – Input Antialias Filter fc ≅ 2 x Symbol Rate 750Ω rxbaudCLK + 0.01µF Compromise Hybrid – + rxHYB+ rx48xCLK Data Out HDSL DSP txbaudCLK 1/2 AFE2124 100pF tx48xCLK 750Ω Data In rxHYB– 750Ω rxLINE– 100pF GNDA 750Ω GNDA rxLINE+ GNDA DVDD DVDD AVDD AVDD AVDD 5V to 3.3V Digital 5V Analog 0.1µF 0.1µF 0.1µF 0.1µF 0.1µF 1 - 10µF FIGURE 6. Basic Connection Diagram for Each Channel of the AFE2124. For the transmit channel, the pulse shape and the power spectral density scale directly with the clock rate. The power spectral density shown in Curve 1 and the pulse template shown in Curve 2 are measured at the output of the transformer. The transformer and the RC circuit on the output provide some smoothing for the output transmission. At lower bit rates, the amount of smoothing will be less. differential inputs should be approximately 1MHz for T1 and E1 symbol rates. Suggested values for the filter are 750Ω for each of the two input resistors and 100pF for the capacitor. Together, the two 750Ω resistors and the 100pF capacitor result in a 3dB frequency of just over 1MHz. The 750Ω input resistors will result in minimal voltage divider loss with the input impedance of the AFE2124. rxHYB AND rxLINE INPUT ANTI-ALIASING FILTERS The anti-aliasing filters will give best performance with 3dB frequency approximately equal to the bit rate. For example, a 3dB frequency of 320kHz may be used for a single line bit rate of 320k bits per second. An external input antialiasing filter is needed on the hybrid and line inputs as shown in Figure 6. The –3dB frequency of the input anti-aliasing filter for the rxLINE and rxHYB ® 9 AFE2124 DISCUSSION OF SPECIFICATIONS change with clock frequency. However, the power dissipation in the digital circuitry does decrease with lower clock frequency. In addition, the power dissipation in the digital section is decreased when operating from a smaller supply voltage, such as 3.3V. (The analog supply, AVDD, must remain in the range 4.75V to 5.25V). UNCANCELED ECHO A key measure of transceiver performance is uncancelled echo. Uncancelled echo is the summation of all of the errors in the transmit and receive paths of the AFE2124. It includes effects of linearity, distortion and noise. Uncancelled echo is tested in production by Burr-Brown with a circuit that is similar to the one shown in Figure 7. The power dissipation listed in the Specifications Table applies under these normal operating conditions: 5V analog power supply; 3.3V digital power supply; standard 13.5dBm delivered to the line; and a pseudo-random equiprobable sequence of HDSL output pulses. The power dissipation specifications includes all power dissipated in the AFE2124; however, it does not include power dissipated in the external load. The external power is 16.5dBm, 13.5dBm to the line, and 13.5dBm to the impedance matching resistors. The external load power of 16.5dBm is 45mW. The typical power dissipation for each half of the AFE2124 under various conditions is shown in Table II. The measurement of uncancelled echo is made as follows: The AFE is connected to an output circuit including a typical 1:2 line transformer. The line is simulated by a 135Ω resistor. Symbol sequences are generated by the tester and applied both to the AFE and to the input of an adaptive filter. The output of the adaptive filter is subtracted from the AFE output to form the uncanceled echo signal. Once the filter taps have converged, the RMS value of the uncancelled echo is calculated. Since there is no far-end signal source or additive line noise, the uncanceled echo contains only noise and linearity errors generated in the transmit and receive sections of the AFE2124. The T1 and E1 power measurements in the Specifications are made with the output circuit shown in Figure 7. This circuit uses a 1:2 transformer. The power measurements shown in Table II use an equivalent resistive load instead of the transformer to eliminate frequency dependent impedances of the transformer. The data sheet value for uncancelled echo is the ratio of the rms uncanceled echo (referred to the receiver input through the receiver gain) to the nominal transmitted signal (13.5dBm into 135Ω, or 1.74Vrms). This echo value is measured under a variety of conditions: with loopback enabled (line input disconnected); with loopback disabled under all receiver gain ranges; and with the line shorted (S1 closed in Figure 7). POWER DISSIPATION Approximately 80% of the power dissipation in the AFE2124 is in the analog circuitry, and this component does not BIT RATE (symbols/sec) DVDD (V) TYPICAL POWER DISSIPATION IN THE AFE2124 (per channel) (mW) 584 (E1) 584 (E1) 392 (T1) 392 (T1) 146 (E1/4) 146 (E1/4) +3.3 +5 +3.3 +5 +3.3 +5 250 300 240 270 230 245 TABLE II. Typical Power Dissipation (per channel). 13Ω Transmit Data txDATP 13Ω txLINEN 1.5kΩ rxHYBP 1/2 AFE2124 100pF 3kΩ Adaptive Filter rxHYBN 1.5Ω 750Ω rxLINEP 100pF rxLINEN 750Ω Uncancelled Echo rxD13 - rxD0 FIGURE 7. Uncancelled Echo Test Diagram. ® AFE2124 1:2 5.6Ω txLINEP 10 5.6Ω 135Ω S1 plane underneath all digital pins is strongly recommended. LAYOUT The remaining portion of the AFE2124 should be considered analog. All AGND pins should be connected directly to a common analog ground plane and all AVDD pins should be connected to an analog 5V power plane. Both of these planes should have a low impedance path to the power supply. The analog power supply pins should be decoupled to analog ground with ceramic 0.1µF capacitors placed as close to the AFE2124 as possible. One 10µF tantalum capacitor should also be used with each AFE2124 between the analog supply and analog ground. The analog front end of an HDSL system has two conflicting requirements. It must accept and deliver moderately high rate digital signals and it must generate, drive, and convert precision analog signals. To achieve optimal system performance with the AFE2124, both the digital and the analog sections must be treated carefully in board layout design. The power supply for the digital section of the AFE2124 can range from 3.3V to 5V. This supply should be decoupled to digital ground with ceramic 0.1µF capacitors placed as close to DGND and DVDD as possible. One capacitor should be placed between pins 7 and 8 and the second capacitor, between pins 41 and 42. Ideally, both a digital power supply plane and a digital ground plane should run up to and underneath the digital pins of the AFE2124 (pins 1 through 6, and pins 43 through 48). However, DVDD may be supplied by a wide printed circuit board (PCB) trace. A digital ground Ideally, all ground planes and traces and all power planes and traces should return to the power supply connector before being connected together (if necessary). Each ground and power pair should be routed over each other, should not overlap any portion of another pair, and the pairs should be separated by a distance of at least 0.25 inch (6mm). One exception is that the digital and analog ground planes should be connected together underneath the AFE2124 by a small trace. ® 11 AFE2124 PACKAGE OPTION ADDENDUM www.ti.com 1-Jul-2015 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) AFE2124E/1K OBSOLETE SSOP DL 48 TBD Call TI Call TI AFE2124E/1KG4 OBSOLETE SSOP DL 48 TBD Call TI Call TI Op Temp (°C) Device Marking (4/5) (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device. (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish value exceeds the maximum column width. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis. Addendum-Page 1 Samples PACKAGE OPTION ADDENDUM www.ti.com 1-Jul-2015 Addendum-Page 2 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All semiconductor products (also referred to herein as “components”) are sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment. TI warrants performance of its components to the specifications applicable at the time of sale, in accordance with the warranty in TI’s terms and conditions of sale of semiconductor products. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where mandated by applicable law, testing of all parameters of each component is not necessarily performed. TI assumes no liability for applications assistance or the design of Buyers’ products. Buyers are responsible for their products and applications using TI components. To minimize the risks associated with Buyers’ products and applications, Buyers should provide adequate design and operating safeguards. TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right relating to any combination, machine, or process in which TI components or services are used. Information published by TI regarding third-party products or services does not constitute a license to use such products or services or a warranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual property of the third party, or a license from TI under the patents or other intellectual property of TI. Reproduction of significant portions of TI information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied by all associated warranties, conditions, limitations, and notices. TI is not responsible or liable for such altered documentation. Information of third parties may be subject to additional restrictions. Resale of TI components or services with statements different from or beyond the parameters stated by TI for that component or service voids all express and any implied warranties for the associated TI component or service and is an unfair and deceptive business practice. TI is not responsible or liable for any such statements. Buyer acknowledges and agrees that it is solely responsible for compliance with all legal, regulatory and safety-related requirements concerning its products, and any use of TI components in its applications, notwithstanding any applications-related information or support that may be provided by TI. Buyer represents and agrees that it has all the necessary expertise to create and implement safeguards which anticipate dangerous consequences of failures, monitor failures and their consequences, lessen the likelihood of failures that might cause harm and take appropriate remedial actions. Buyer will fully indemnify TI and its representatives against any damages arising out of the use of any TI components in safety-critical applications. In some cases, TI components may be promoted specifically to facilitate safety-related applications. With such components, TI’s goal is to help enable customers to design and create their own end-product solutions that meet applicable functional safety standards and requirements. Nonetheless, such components are subject to these terms. No TI components are authorized for use in FDA Class III (or similar life-critical medical equipment) unless authorized officers of the parties have executed a special agreement specifically governing such use. Only those TI components which TI has specifically designated as military grade or “enhanced plastic” are designed and intended for use in military/aerospace applications or environments. Buyer acknowledges and agrees that any military or aerospace use of TI components which have not been so designated is solely at the Buyer's risk, and that Buyer is solely responsible for compliance with all legal and regulatory requirements in connection with such use. TI has specifically designated certain components as meeting ISO/TS16949 requirements, mainly for automotive use. In any case of use of non-designated products, TI will not be responsible for any failure to meet ISO/TS16949. Products Applications Audio www.ti.com/audio Automotive and Transportation www.ti.com/automotive Amplifiers amplifier.ti.com Communications and Telecom www.ti.com/communications Data Converters dataconverter.ti.com Computers and Peripherals www.ti.com/computers DLP® Products www.dlp.com Consumer Electronics www.ti.com/consumer-apps DSP dsp.ti.com Energy and Lighting www.ti.com/energy Clocks and Timers www.ti.com/clocks Industrial www.ti.com/industrial Interface interface.ti.com Medical www.ti.com/medical Logic logic.ti.com Security www.ti.com/security Power Mgmt power.ti.com Space, Avionics and Defense www.ti.com/space-avionics-defense Microcontrollers microcontroller.ti.com Video and Imaging www.ti.com/video RFID www.ti-rfid.com OMAP Applications Processors www.ti.com/omap TI E2E Community e2e.ti.com Wireless Connectivity www.ti.com/wirelessconnectivity Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265 Copyright © 2015, Texas Instruments Incorporated