XRT5794IJ-F

XR-T5794 ...the analog plus Quad E-1 Line Interface Unit company TM June 1997-3
Individual Channel Loss of Signal Detection, Local and Remote Digital Loopback FEATURES
Meets CCITT G.703 Pulse Mask Template for 2.048Mbps (E1) Rates
Fifth Driver For Monitoring and Testing
Low Power, CMOS Technology
Transmitter and Receiver Interfaces Can Be:
Over-temperature Protection – Single Ended, 75Ω Capacitive or Transformer Coupled APPLICATIONS – Balanced, 100 or 120Ω Transformer Coupled
Multi-Line E1 Interface Cards
Minimum Return Loss is 20dB (Receive) and 18dB (Transmit), Exceeds G.703 and ETSI 300 166 Specifications
E1 Network Equipment – Multiplexers
Bipolar Outputs can be Disabled Individually (High Z Outputs) – Cross Connects – Switching Systems
System Interface is TTL Compatible on Digital Input and TTL/CMOS Compatible On Digital Output Pins
Fault Tolerant Systems GENERAL DESCRIPTION sensitivity of 600mV over the operating temperature range. Return loss on the receive interfaces is minimum 20dB from 51kHz to 3.072MHz. The XR-T5794 is an optimized line interface unit, built using low power CMOS technology. The device contains four independent E1 channels for primary rate, PCM applications up to 2.048Mbps. Each channel performs the driver and receiver functions necessary to convert bipolar signals to TTL/CMOS compatible logic levels and vice versa. The device supports single ended or balanced line interfaces on each channel, thereby providing the user an option of reducing system cost and board space by replacing the transformer with a capacitor. Local and remote loopbacks can be performed on any of the four channels. A separate loss of signal (LOS) detection circuitry and a LOS pin is provided for each input. A fifth transmitter has been provided to support dedicated monitoring and testing purposes on any of the eight bipolar paths. For designers not requiring the fifth (monitor) driver, EXAR offers the XR-T5793, a pin compatible version of the XR-T5794. Each of the four drivers can be independently disabled, allowing maximum flexibility in system power management. Output pulses are fully CCITT G.703 compliant. Moreover, the return loss is at least 18dB over a frequency range of 51kHz to 3.072MHz. The XR-T5794 is targeted for multi-line E1 line card applications where real estate, low power consumption and back-up redundancy are critical. Also, the device may be used in T1 applications (1.544Mbps) which do not require meeting the DSX-1 cross connect pulse template. The slicing circuit in the receive path is able to tolerate a maximum of 12dB of cable loss with a minimum input ORDERING INFORMATION Part No. Package Operating Temperature Range XR-T5794IJ 68 Lead PLCC -40°C to +85°C XR-T5794IV 80 Lead TQFP (14x14x1.4 mm) -40°C to +85°C Rev. 2.02 1994 EXAR Corporation, 48720 Kato Road, Fremont, CA 94538  (510) 668-7000  (510) 668-7017 1 XR-T5794 BLOCK DIAGRAM 75Ω Unbalanced (Without Transformer) TIP 0.47
F Impedance Selectable Receivers. Return Loss Exceeds G.703 75 Level Detector 120Ω Balanced TIP (or 100Ω ) RX INPUT RING Impedance Selectable Tristate Drivers Return Loss Exceeds ETSI 300 166 Slicer RXIN 100 or 120 PE–65834 TTI 7148 Transceiver 1 Transceiver 2 Transceiver 3 Transceiver 4 LOS Peak Detector E1/T1- Slice Voltage 2 LOOPEN(1.4) LOS Threshold Based on G.775 L o c a l / R e m o t e RXPOS RXNEG LPMOD(1.4) 120Ω ,100Ω or 75Ω balanced TXOUT TIP TX OUTPUT RING Driver ROUT1 PE–65839 TTI 7149 75Ω Unbalanced (Without Transformer) L o o p b a c k TXEN TXPOS TXNEG TXCLK Channel 1 TIP 0.47µF ROUT1 Channel 2 Driver Channel 3 MUX Channel 4 MSEL (0.2) MONEM Note 1R OUT = 68Ω for 120Ω line impedance, ROUT = 62Ω for 100Ω line impedance, ROUT = 68Ω for 75Ω line impedance Figure 1. Block Diagram Rev. 2.01 2 MOUT XR-T5794 TXEN2 TXOUT1 TXEN1 TV DD MOUT TV AGND TXOUT2 TV TV DD SS SS SS TXEN3 TXEN4 TXOUT4 TV DD TV TXOUT3 AGND PIN CONFIGURATION 2 1 68 MONEN AVDD 10 60 LOSLVS AVSS TXCLK2 TXPOS2 TXNEG2 TXCLK1 TXPOS1 TXNEG1 LOOPEN2 LOOPEN1 E1/T1VSS RXPOS2 RXNEG2 RXPOS1 RXNEG1 RVSS TCLK4 TXPOS4 TXNEG4 TXCLK3 TXPOS3 TXNEG3 LOOPEN4 LOOPEN3 GND VDD RXPOS3 RXNEG3 RXPOS4 RXNEG4 44 26 RXIN2 LOS1 LOS2 RGND MSEL2 MSEL1 RGND 43 LOS3 RXIN3 MSEL0 LPMOD4 LPMOD3 RXIN4 LOS4 27 RXIN1 LPMOD2 LPMOD1 RVDD LOSLVS AVSS AVSS AVSS TXCLK2 TXPOS2 TXNEG2 TXCLK1 TXPOS1 TXNEG1 LOOPEN2 LOOPEN1 E1/T1VSS RXPOS2 RXNEG2 RXPOS1 RXNEG1 RVSS RVSS 68 Lead PLCC 60 NC NC TXEN2 TXEN1 TXOUT1 TVDD TVSS TXOUT2 AGND TVSS MOUT TVDD AGND TXOUT3 TVSS TVDD TXOUT4 TXEN4 TXEN3 NC 41 61 40 80 21 20 NC MONEN AV DD AV DD TXCLK4 TXPOS4 TXNEG4 TXCLK3 TXPOS3 TXNEG3 LOOPEN4 LOOPEN3 GND V DD RXPOS3 RXNEG3 RXPOS4 RXNEG4 RV DD RV DD 1 80 Lead TQFP (14 x 14 x 1.4 mm) Rev. 2.01 3 NC NC LPMOD1 LPMOD2 RXIN1 LOS2 LOS1 RXIN2 MSEL2 RGND RGND RGND MSEL1 MSEL0 RXIN3 LOS3 LOS4 RXIN4 LPMOD3 LPMOD4 XR-T5794 PIN DESCRIPTION PLCC Pin # SQFP Pin # Symbol Type 1 71 MOUT O 2 72 TVDD VDD Transmit VDD. 5V (
5%). 3 73 AGND GND Analog Ground. 4 74 TXOUT3 O 5 75 TVSS VSS Transmit VSS. -5V (
5%). 6 76 TVDD VDD Transmit VDD. +5V (
5%). 7 77 TXOUT4 O Transmitter 4 Output. Transmitter 4 bipolar output connected to coupling capacitor or pulse transformer by a resistor. 8 78 TXEN4 I Transmitter 4 Output Enable. If driven high the transmitter 4 output drivers are enabled. Hi-Z otherwise. 9 79 TXEN3 I Transmitter 3 Output Enable. If driven high the transmitter 3 output drivers are enabled. Hi-Z otherwise. 10 2 MONEN I Monitor/Test Output Enable. If driven high the output driver of the MOUT output is enabled. Hi-Z otherwise. Description Signal Monitor Output. If MONEN=1, this output tracks the selected signal. Hi-Z otherwise. The channel selection is done using MONSEL[2..0] inputs. Transmitter 3 Output. Transmitter 3 bipolar output connected to coupling capacitor or pulse transformer by a resistor. 11 3,4 AVDD VDD 12 5 TXCLK4 I Analog VDD. Transmitter 4 Clock Input. Apply logic one when RZ signals are supplied to data inputs. 13 6 TXPOS4 I Transmitter 4 Positive Data In. Positive data input in NRZ or RZ format for transmitter 4. 14 7 TXNEG4 I Transmitter 4 Negative Data In. Negative data input in NRZ or RZ format for transmitter 4. 15 8 TXCLK3 I Transmitter 3 Clock Input. Apply logic one when RZ signals are supplied to data inputs. 16 9 TXPOS3 I Transmitter 3 Positive Data In. Positive data input in NRZ or RZ format for transmitter 3. 17 10 TXNEG3 I Transmitter 3 Negative Data In. Negative data input in NRZ or RZ format for transmitter 3. 18 11 LOOPEN4 I Loop Enable 4. If driven high the specified loop type will be enabled for channel 4. Otherwise normal operation will continue. 19 12 LOOPEN3 I Loop Enable 3. If driven high the specified loop type will be enabled for channel 3. Otherwise normal operation will continue. 20 13 GND GND Digital Ground. 21 14 VDD VDD Digital VDD. +5V (
5%). 22 15 RXPOS3 O Receiver 3 Positive Data Out. Positive data output in NRZ or RZ format for receiver 3. 23 16 RXNEG3 O Receiver 3 Negative Data Out. Negative data output in NRZ or RZ format for receiver 3. 24 17 RXPOS4 O Receiver 4 Positive Data Out. Positive data output in NRZ or RZ format for receiver 4. Rev. 2.01 4 XR-T5794 PIN DESCRIPTION (CONT’D) PLCC Pin # SQFP Pin # Symbol Type 25 18 RXNEG4 O 26 19, 20 RVDD VDD 27 21 LPMOD4 I Loop Mode 4. If driven high the loopback mode of channel 4 will be set to remote loop. Otherwise theloopback mode will remain at local loop. The actual loopback will be activated when the LOOPEN4 is asserted. 28 22 LPMOD3 I Loop Mode 3. If driven high the loopback mode of channel 3 will be set to remote loop. Otherwise the loopback mode will remain at local loop. The actual loopback will be activated when the LOOPEN3 is asserted. 29 23 RXIN4 I Receiver 4 Input. Receiver 4 bipolar input connected to coupling capacitor or pulse transformer. 30 24 LOS4 O Receiver 4 Loss Of Signal. Asserted during LOS condition. Clear otherwise. 31 25 LOS3 O Receiver 3 Loss Of Signal. Asserted during LOS condition. Clear otherwise. 32 26 RXIN3 I Receiver 3 Input. Receiver 3 bipolar input connected to coupling capacitor or pulse transformer. 33 27 MSEL0 I Monitor Channel Select 0. Select line, used to select a channel for monitoring using the MOUT pin based on the following assignment: Description Receiver 4 Negative Data Out. Negative data output in NRZ or RZ format for receiver 4. Receive VDD. +5V (
5%). MSEL2 0 0 0 0 1 1 1 1 MSEL1 0 0 1 1 0 0 1 1 MSEL0 0 1 0 1 0 1 0 1 SELECTS Line 1 Receive Line 2 Receive Line 3 Receive Line 4 Receive Line 1 Transmit Line 2 Transmit Line 3 Transmit Line 4 Transmit Note The monitoring is only done on the NRZ data output signals from the receiver or from the transmitter line side. 34 28 MSEL1 I Monitor Channel Select 1. See table above. 35 29, 30 RGND GND Receive Ground. 36 31 RGND GND Receive Ground. 37 32 MSEL2 I Monitor Channel Select 2. See table above. 38 33 RXIN2 I Receiver 2 Input. Receiver 2 bipolar input connected to coupling capacitor or pulse transformer. 39 34 LOS1 O Receiver 1 Loss Of Signal. Asserted during LOS condition. Clear otherwise. 40 35 LOS2 O Receiver 2 Loss Of Signal. Asserted during LOS condition. Clear otherwise. 41 36 RXIN1 I Receiver 1 Input. Receiver 1 bipolar input connected to coupling capacitor or pulse transformer. 42 37 LPMOD2 I Loop Mode 2. If driven high the loopback mode of channel 2 will be set to remote loop. Otherwise the loopback mode will remain at local loop. The actual loopback will be activated when the LOOPEN2 is asserted. Rev. 2.01 5 XR-T5794 PIN DESCRIPTION (CONT’D) PLCC Pin # SQFP Pin # Symbol Type 43 38 LPMOD1 I 44 41, 42 RVSS VSS 45 43 RXNEG1 O Receiver 1 Negative Data Out. Negative data output in NRZ or RZ format for receiver 1. 46 44 RXPOS1 O Receiver 1 Positive Data Out. Positive data output in NRZ or RZ format for receiver 1. 47 45 RXNEG2 O Receiver 2 Negative Data Out. Negative data output in NRZ or RZ format for receiver 2. 48 46 RXPOS2 O Receiver 2 Positive Data Out. Positive data output in NRZ or RZ format for receiver 2. 49 47 VSS VSS 50 48 E1/T1- I E1/T1- Selection. Apply logic one to select the receive data threshold appropriate for E1 operation. Connect to ground to select the T1 data threshold. 51 49 LOOPEN1 I Loop Enable 1. If driven high the specified loopback mode will be enabled for channel 1. Otherwise normal operation will continue. 52 50 LOOPEN2 I Loop Enable 2. If driven high the specified loopback mode will be enabled for channel 2. Otherwise normal operation will continue. 53 51 TXNEG1 I Transmitter 1 Negative Data In. Negative data input in NRZ or RZ format for transmitter 1. 54 52 TXPOS1 I Transmitter 1 Positive Data In. Positive data input in NRZ or RZ format for transmitter 1. 55 53 TXCLK1 I Transmitter 1 Clock Input. Apply logic one when RZ signals are supplied to data inputs. 56 54 TXNEG2 I Transmitter 2 Negative Data In. Negative data input in NRZ or RZ format for transmitter 2. 57 55 TXPOS2 I Transmitter 2 Positive Data In. Positive data input in NRZ or RZ format for transmitter 2. 58 56 TXCLK2 I Transmitter 2 Clock Input. Apply logic one when RZ signals are supplied to data inputs. 59 57, 58, 59 AVSS VSS 60 60 LOSLVS I Loss of Signal Voltage Select. Apply logic one to select LOS voltage level appropriate for 120Ω balanced receiver operation. Connect to ground to choose LOS voltage for 75Ω unbalanced operation. 61 63 TXEN2 I Transmitter 2 Output Enable. If asserted the transmitter 2 output drivers are enabled. High-Z otherwise. 62 64 TXEN1 I Transmitter 1 Output Enable. If asserted the transmitter 1 output drivers are enabled. High-Z otherwise. 63 65 TXOUT1 O Transmitter 1 Output. Transmitter 1 bipolar output connected to coupling capacitor or pulse transformer through a resistor. 64 66 TVDD VDD Transmit VDD. +5V (
5%). 65 67 TVSS VSS Transmit VSS. -5V (
5%). Description Loop Mode 1. Iif driven high the loopback mode of channel 1 will be set to remote loop. Otherwise the loopback mode will remain at local loop. The actual loopback will be activated when the LOOPEN1 is asserted. Receive VSS. -5V (
5%). Digital VSS. -5V (
5%). Analog VSS. Rev. 2.01 6 XR-T5794 PIN DESCRIPTION (CONT’D) PLCC Pin # SQFP Pin # Symbol Type 66 68 TXOUT2 O 67 69 AGND GND Analog Ground. 68 70 TVSS VSS Transmit VSS. -5V (
5%). - 1, 39, 40, 61, 62, 80 NC Description Transmitter 2 Output. Transmitter 2 bipolar output connected to coupling capacitor or pulse transformer through a resistor. No Connect. Rev. 2.01 7 XR-T5794 DC ELECTRICAL CHARACTERISTICS Test Conditions: TA = -40°C to 25°C to 85°C, all VDDs = 5V
5%, all VSSs = -5V
5%, all GNDs = 0V Symbol Parameter Min. Typ. Max. Unit VDDs DC Supply Positive 4.75 5.00 5.25 V VSSs DC Supply Negative -4.75 -5.00 -5.25 V VIH High Level Input 2.0 VIL Low Level Input 0.8 V IPDC Input Pull Down Current 40 mA Conditions DC Parameters Inputs V Outputs VOH High Level Output 3.5 V IOH = -10mA VOH High Level Output 2.4 V IOH = -40mA VOL Low Level Output 0.4 V IOL = 1.6mA 4.2 Vp 12 12 dB dB 1.024MHz (E1) 772kHz (T1) dB With 6dB Cable Loss Receiver Specifications RXP Receiver Sensitivity 0.6 RXCL Allowed Cable Loss (0dB=2.4V) 0 0 RXIWT Interference Margin (E1) 16 10 10 RXTI Receiver Slicing Level (T1)1 60 65 70 % Peak Voltage % RXEI Receiver Slicing Level (E1)1 45 50 55 % Peak Voltage % RXLOS Receiver LOS Threshold 0.2 0.3 V RIN Input Resistance 2.5 kW Up to 3.072MHz Power Specifications (Without Monitor Channel) PD Power Dissipation 400 680 mW PD Power Dissipation 250 280 mW All Drivers in High-Z PC Power Consumption 75Ω2 500 833 mW All 1’s Transmit & Receive PC Power Consumption 100Ω2 475 860 mW All 1’s Transmit & Receive PC Power Consumption 120Ω2 450 830 mW All 1’s Transmit & Receive PVDD Power Supply Requirement Pc/2 + 5mW mW PVSS Power Supply Requirement Pc/2 - 5mW mW Notes 1 Selected by E1/T1 2 Power consumption = power dissipation + power to the cable. Bold face parameters are covered by production test and guaranteed over operating temperature range. Specifications are subject to change without notice Rev. 2.01 8 XR-T5794 AC ELECTRICAL CHARACTERISTICS Test Conditions: TA = -40°C to 25°C to 85°C, all VDDs = 5V
5%, all VSSs = -5V
5%, all GNDs = 0V Symbol Parameter Min. Typ. Max. Unit Conditions VTXOUT Output Pulse Amplitude (75Ω) 2.13 2.37 2.60 V VTXOUT Output Pulse Amplitude (120Ω) 2.70 3.0 3.30 V VTXOUT Output Pulse Amplitude (100Ω) 2.3 3.0 3.7 V TXPW Pulse Width (2.048MHz) 224 244 264 ns Determined by TX Clock TXPW Pulse Width (1.544MHz) 274 324 374 ns Determined by TX Clock PNIMB Pos/Neg Pulse Imbalance -5 5 % T1 TXCLK Clock Period (E1) 488 ns T2 TXCLK Clock Period (T1) 648 ns T3 TXCLK Duty Cycle 48 T4 Data Setup Time, TDATA to TCLK 50 ns T5 Data Hold Time, TCLK to 50 ns 50 52 % TDATA TR Clock Rise Time 30 ns TF Clock Fall Time 30 ns T6 Receive Data High (E1) 269 ns T7 Data Propagation Delay 100 ns T8 Receive Rise Time 50 ns T9 Receive Fall Time 50 ns 219 244 0dB Cable Loss Notes Bold face parameters are covered by production test and guaranteed over operating temperature range. Specifications are subject to change without notice ABSOLUTE MAXIMUM RATINGS Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7V Storage Temperature . . . . . . . . . . . . -65°C to +150°C Rev. 2.01 9 XR-T5794 TXPOS(n) TXNEG(n) T4 T5 T5 T4 TXCLK(n) T3 T7 T3 T7 TXOUT(n) Figure 2. Transmit Timing Diagram RXIN T7 T6 T8 T9 RXPOS T9 T7 T8 RXNEG T6 Figure 3. Receive Timing Diagram T1 or T2 T3 T3 TXCLK(n) TR Figure 4. Transmit Clock Timing Rev. 2.01 10 TF XR-T5794 RETURN LOSS REQUIREMENTS 75Ω 100Ω 120Ω Transmit Interface Min. Typ. Min. Typ. Min. Typ. Units 51kHz to 102kHz 18 22 18 22 18 22 dB 102kHz to 2.048MHz 18 22 18 22 18 22 dB 2.048MHz to 3.072MHz 18 22 18 22 18 22 dB Receive Interface Min. Typ. Min. Typ. Min. Typ. Units 51kHz to 102kHz 20 30 20 30 20 30 dB 102kHz to 2.048MHz 20 30 20 30 20 30 dB 2.048MHz to 3.072MHz 20 30 20 30 20 30 dB 75Ω 100Ω 120Ω Note The return loss has been measured on the evaluation board coupled via a capacitor and terminated with 75
impedance. Table 1. Return Loss Requirements (Resistor Tolerance: 1% on Transmit Side, 2% on Receive Side) Turns Ratio Line Impedance RLOAD Turns Ratio Line Impedance ROUT 1:1 75Ω 75Ω 1:1 75Ω 68Ω 1:1 120Ω 120Ω 1:1.265 120Ω 68Ω 1:1 100Ω 100Ω 1:1.265 100Ω 62Ω Table 2. Input Transformer Requirements Table 3. Output Transformer Requirements Magnetic Supplier Information: Transpower Technologies, Inc. 24 Highway 28, Suite 202 Crystal Bay, NV 89402–0187 Tel. (702) 831–0140 Fax. (702) 831–3521 Pulse Telecom Product Group P.O. Box 12235 San Diego, CA 92112 Tel. (619) 674-8100 Fax. (619) 674-8262 Rev. 2.01 11 XR-T5794 SYSTEM DESCRIPTION TRANSMITTERS This device is a quad E1 transceiver which provides electrical interface for 2.048Mbps applications. Its unique architecture includes four receiver circuits that convert CCITT G.703 compliant bipolar signals to TTL compatible logic levels. Likewise, in the other direction, four transmitters translate TTL compatible logic levels to G.703 compatible bipolar signals. A fifth transmitter circuit is used as a monitor output. One of the four AMI receiver inputs or transmitter outputs can be selected (via MONSEL[2..0] lines) to be monitored. The MOUT output can be disabled using the MONEN signal. This device contains five identical CCITT G.703 compliant transmitters which meet the return loss requirements. Each transmitter is a single-ended voltage driver. External resistors are used to maintain an accurate source impedance that has a high return loss to the transformer or the capacitor. Each of the drivers can be individually disabled, this is required in fault tolerant applications where redundancy is a requirement. During power-down mode of operation the bipolar outputs can be disabled. To protect the data integrity during a brownout, the output pulse amplitudes are reduced by a factor of 25% if the supply drops below an internally set limit. This device supports two different types of loopback functions. Each of four channels can be independently looped either in local or remote sides digitally. The remote loopback is performed between the receiver input and transmitter output. To activate the remote loopback on channel n, LOOPENn and LPMODn inputs are driven high. Local loopback on channel n, can be established similarly by driving LOOPENn high and clearing LPMODn inputs. More than one channel can be tested simultaneously. Transmission is possible either with or without a clock. If a clock is used, the transmit input data must consist of full-width NRZ pulses, and the transmitter output pulse width is determined by the duty cycle of the clock. If the transmit clock is tied high, the transmitter output pulses are determined by the input data pulse width. In this mode, RZ data must be supplied to the device. RECEIVERS TXP TXN Each of the four identical E1 line receivers will accept bipolar signals meeting the CCITT G.703 pulse mask requirements. Each input stage consists of a slicing circuitry which samples the incoming pulses at a fixed percentage of the signals maximum amplitude. The slicing voltage level is generated using a precision peak detector. The receiver section can tolerate up to 12dB of line loss (measured at 1.024MHz). TXOUT RXIN RX TX LPMOD=1 LPEN=1 RXP RXN Remote Loopback TXP TXN A loss of signal (LOS) is detected on any inputs by input fail circuitry. There is an independent LOS pin dedicated for each of the receivers. The LOS detection is based on signal energy instead of number of zeros. RXIN TXOUT RX TX LPMOD=0 LPEN=1 A balanced signal (100Ω or 120Ω) must be coupled by a transformer. An unbalanced signal (75Ω) may be coupled via a capacitor or transformer coupled. RXP RXN Local Loopback Figure 5. Loopback Configurations Rev. 2.01 12 XR-T5794 Output Transformer Selection 3. Calculate the source resistance, RS. The 1:1.265 ratio output transformer is recommended for the XR-T5794 because this ratio gives the best possible transmitter output return loss for 120Ω balanced E1 service. However, other transformers may provide an adequate return loss for many applications. The two characteristics that determine series build-out resistor requirements are: Vs * 1 Ǔ ǒVeq Rs + Req 4. Now calculate the theoretical return loss.
Driver output impedance is less than 5Ω. Return Loss + 20 log
Vs, which is the driver open circuit output voltage, is 4.5V peak. Req ) Rs ǒReq Ǔ * Rs The following method may be used to determine transformer suitability for a given use. The calculation given below uses the recommended 1. List the application requirements. 1:1.265 ratio transformer as an example: Transformer Ratio = 1 :1.265 Transformer Ratio = 1:n Vo = Peak Output Pulse Amplitude RL= Load Resistance VO = 3.0V Peak RL = 120Ω Rs 1:n 3 4 Req + 1 VO Vs RL 2 RL + 120 + 75Ω 1.6 n2 V Veq + no + 3.0 + 2.37V 1.265 Figure 6. Equivalent Impedance Schematic Rs + Req 2. Calculate equivalent output voltage and load resistance without the transformer. Req + RL n2 Vs * 1 Ǔ + 75 ǒ 4.5 * 1 Ǔ + 67.4Ω ǒVeq 2.37 V Veq + no (Datasheet specifies standard value of 68Ω) Rs Calculate the theoretical return loss to determine if the transformer is acceptable. Vs Req Veq ǒ Ǔ Return Loss + 20 log 75 ) 67.4 + 25.5dB 75 * 67.4 Figure 7. Equivalent Simplified Schematic Rev. 2.01 13 XR-T5794 269 ns (244 + 25) Nominal pulse 20% 10% V = 100% 194 ns (244 – 50) 10% 20% 50% 244 ns 219 ns (244 – 25) 10% 10% 0% 10% 20% 488 ns (244 + 244) Note: V corresponds to the nominal peak value Figure 8. CCITT G.703 Pulse Template Rev. 2.01 14 10% XR-T5794 68 LEAD PLASTIC LEADED CHIP CARRIER (PLCC) Rev. 1.00 D C Seating Plane D1 45° x H1 A2 45° x H2 2 1 68 B1 B D D2 D3 D1 e R D3 A1 A INCHES SYMBOL MILLIMETERS MIN MAX MIN MAX A 0.165 0.200 4.19 5.08 A1 0.090 0.130 2.29 3.30 A2 0.020 ---. 0.51 --- B 0.013 0.021 0.33 0.53 B1 0.026 0.032 0.66 0.81 C 0.008 0.013 0.19 0.32 D 0.985 0.995 25.02 25.27 D1 0.950 0.958 24.13 24.33 D2 0.890 0.930 22.61 23.62 D3 0.800 typ. 20.32 typ. e 0.050 BSC 1.27 BSC H1 0.042 0.056 1.07 1.42 H2 0.042 0.048 1.07 1.22 R 0.025 0.045 0.64 1.14 Note: The control dimension is the inch column Rev. 2.01 15 XR-T5794 80 LEAD THIN QUAD FLAT PACK (14 x 14 x 1.4 mm, TQFP) Rev. 3.00 D D1 60 41 61 40 D1 80 21 1 20 A2 B e C A Seating Plane α A1 L INCHES SYMBOL A A1 A2 B C D D1 e L α MIN MILLIMETERS MAX MIN 0.055 0.063 0.002 0.006 0.053 0.057 0.009 0.015 0.004 0.008 0.622 0.638 0.547 0.555 0.0256 BSC 0.018 0.030 1.40 0.05 1.35 0.22 0.09 15.80 13.90 0° 7° 1.60 0.15 1.45 0.38 0.20 16.20 14.10 0.65 BSC 0.45 0.75 0° Note: The control dimension is the millimeter column Rev. 2.01 16 MAX 7° D XR-T5794 Notes Rev. 2.01 17 XR-T5794 Notes Rev. 2.01 18 XR-T5794 Notes Rev. 2.01 19 XR-T5794 NOTICE EXAR Corporation reserves the right to make changes to the products contained in this publication in order to improve design, performance or reliability. EXAR Corporation assumes no responsibility for the use of any circuits described herein, conveys no license under any patent or other right, and makes no representation that the circuits are free of patent infringement. Charts and schedules contained herein are only for illustration purposes and may vary depending upon a user’s specific application. While the information in this publication has been carefully checked; no responsibility, however, is assumed for inaccuracies. EXAR Corporation does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless EXAR Corporation receives, in writing, assurances to its satisfaction that: (a) the risk of injury or damage has been minimized; (b) the user assumes all such risks; (c) potential liability of EXAR Corporation is adequately protected under the circumstances. Copyright 1994 EXAR Corporation Datasheet June 1997 Reproduction, in part or whole, without the prior written consent of EXAR Corporation is prohibited. Rev. 2.01 20