19-1801; Rev 1; 1/01 +3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers Features ♦ Industry’s First +3.3V Multiprotocol Termination Networks and Transceivers ♦ Certified TBR-1 and TBR-2 Compliant (NET1 and NET2) ♦ Support V.28 (RS-232), V.11 (RS-422, RS-530, RS530A, RS-449, V.36, and X.21), V.10 and V.35 ♦ 3V/5V Logic-Compatible I/O ♦ Software-Selectable DTE/DCE ♦ Replace Discrete Resistor Termination Networks and Expensive Relays ♦ 10µs Receiver Input Deglitching (MAX3172 only) ♦ Available in Small 28-Pin SSOP Package ♦ Transmitter Output Fault Protected to ±15V, Tolerates Cable Miswiring Ordering Information PART TEMP. RANGE PIN-PACKAGE MAX3172CAI 0°C to +70°C 28 SSOP MAX3174CAI 0°C to +70°C 28 SSOP ________________________Applications Data Networking CSU and DSU Data Routers MAX3171 MAX3173 PCI Cards Telecommunications Pin Configuration appears at end of data sheet. Typical Operating Circuit CTS DSR R3 R2 R1 DCD DTR RTS D3 D2 D1 LL RXD RXC R3 R2 TXC R1 D3 SCTE TXD D2 D1 MAX3170 MAX3172 MAX3174 R4 12 15 11 24 14 2 TXD B TXD A 9 17 SCTE B SCTE A DB-25 CONNECTOR 16 3 TXC B TXC A 18 RXD B RXD A RXC B RXC A 7 LL A DCD B DCD A 1 SG DSR B DSR A 23 20 19 4 SHIELD 22 6 RTS B RTS A 10 8 DTR B DTR A 13 5 CTS B CTS A D4 ________________________________________________________________ Maxim Integrated Products 1 For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. MAX3172/MAX3174 General Description The MAX3172/MAX3174 contain five software-selectable multiprotocol cable termination networks. Each network is capable of terminating V.11 (RS-422, RS530, RS-530A, RS-449, V.36, and X.21) with a 100Ω differential load, V.35 with a T-network load, or V.28 (RS-232) and V.10 (RS-423) with an open circuit load for use with transceivers having on-chip termination. The devices replace discrete resistor termination networks and expensive relays required for multiprotocol termination. The MAX3172/MAX3174, along with the MAX3170 and MAX3171/MAX3173, form a complete +3.3V software-selectable DTE or DCE interface port supporting V.11/RS-422, RS-530, RS-530A, V.36/RS449, V.35, V.28/RS-232, V.10/RS-423, and X.21 serial interfaces. In addition to the five multiprotocol cable termination networks, the MAX3172/MAX3174 contain a 1Tx/1Rx multiprotocol transceiver designed to use V+ and Vgenerated by the MAX3171/MAX3173 charge pump. The MAX3172/MAX3174 transceiver is software selectable between V.10 and V.28 modes of operation. The MAX3172 features 10µs deglitching on the V.10/V.28 receiver input to facilitate unterminated operation, while the MAX3174 is used in applications that do not require deglitching on the serial handshake signals. These devices are available in a 28-pin SSOP package. MAX3172/MAX3174 +3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers ABSOLUTE MAXIMUM RATINGS (All voltages referenced to GND unless otherwise noted.) Supply Voltages VCC ......................................................................-0.3V to +4V V+ (Note 1) ..........................................................-0.3V to +7V V- (Note 1) ...........................................................+0.3V to -7V V+ to V- (Note 1) ...............................................................13V Logic Input Voltages M0, M1, M2, DCE/DTE, INVERT, T4IN ................-0.3V to +6V Logic Output Voltages R4OUT...................................................-0.3V to (VCC + 0.3V) Short-Circuit Duration............................................Continuous Transmitter Outputs T4OUT ................................................................-15V to +15V Short-Circuit Duration ........................................................60s Receiver Input R4INA .................................................................-15V to +15V Termination Network Inputs (applied individually) R_A, R_B ............................................................-15V to +15V Continuous Power Dissipation (TA = +70°C) 28-Pin SSOP (derate 9.52mW/°C above +70°C) ........762mW Operating Temperature Range MAX3172CAI/MAX3174CAI ...............................0°C to +70°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C Note 1: V+ and V- can have maximum magnitudes of 7V, but their absolute difference cannot exceed 13V. Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VCC = +3.3V ± 5%, TA = TMIN to TMAX. Typical values are at VCC = +3.3V, TA = +25°C, unless otherwise noted. See Note 2 for V+ and V- input voltage conditions.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX All modes V.10 receiver inactive 80 200 All modes V.10 receiver active No-cable mode 400 750 0.2 1.0 V.10/V.11/V.28/V.35 modes unloaded 0.5 2.5 V.10/V.11 modes T4OUT loaded 11.0 14.0 UNITS DC CHARACTERISTICS Supply Current (Digital Inputs = GND or VCC) V+ Supply Current (T4IN = GND) V- Supply Current (T4IN = VCC) ICC IV+ IV- V.28/V.35 modes T4OUT loaded 3.0 5.0 No-cable mode -0.4 -1.0 V.10/V.11/V.28/V.35 modes unloaded -0.8 -2.5 V.10/V.11 modes T4OUT loaded -11.0 -14.0 V.28/V.35 modes T4OUT loaded -3.0 -5.0 µA mA mA TERMINATOR NETWORKS (R_A, R_B) Differential-Mode Impedance V.35 Mode Figure 1, -2V ≤ VCM ≤ +2V 90 104 110 Ω Common-Mode Impedance V.35 Mode Figure 2, -2V ≤ VCM ≤ +2V 135 153 165 Ω Differential-Mode Impedance V.11 Mode Figure 1, -7V ≤ VCM ≤ +7V 100 104 110 Ω Switches open, -15V ≤ VA ≤ +15V, VB = VA, VB = GND or VB floating 50 150 Network OFF Impedance IZ kΩ LOGIC INPUTS (M0, M1, M2, INVERT, DCE/DTE, T4IN) Input High Voltage VIH Input Low Voltage VIL Logic Input Current 2 IIH, IIL 2.0 VIN = VCC or GND _______________________________________________________________________________________ V 0.8 V ±1 µA +3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers (VCC = +3.3V ± 5%, TA = TMIN to TMAX. Typical values are at VCC = +3.3V, TA = +25°C, unless otherwise noted. See Note 2 for V+ and V- input voltage conditions.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 0.4 V LOGIC OUTPUT (R4OUT) Output High Voltage VOH ISOURCE = 1.0mA Output Low Voltage VOL ISINK = 1.6mA Rise or Fall Time tr, tf 10% to 90%, CL = 15pF VCC - 1.0 15 R4OUT = GND Output Leakage Current (Receiver Output Three-Stated) V 30 R4OUT = VCC ns 50 100 0.1 1 µA TRANSMITTER OUTPUT (T4OUT) Output Leakage Current IZ Data Rate -0.25V < VT4OUT < +0.25V, power-off or no-cable mode -100 V.10/V.28 100 240 µA kbps RECEIVER INPUT (R4INA) Minimum pulse width passed Receiver Glitch Rejection (MAX3172 only) Receiver Input Resistance 5 Maximum pulse width rejected RIN Data Rate 15 V.10 enabled, -10V ≤ VR4INA ≤ +10V 20 40 V.28 enabled, -15V ≤ VR4INA ≤ +15V 3 5 MAX3172 64 MAX3174 240 7 µs kΩ kbps V.10 TRANSMITTER Output Voltage Swing VODO RL = 3.9kΩ, Figure 3 Loaded Output Voltage Swing VODL RL = 450Ω, Figure 3 ±4.0 ±4.4 ±6.0 0.9 × VODO V V ±100 ±150 Short-Circuit Current ISC T4OUT = GND Rise or Fall Time tr, tf 10% to 90%, RL = 450Ω, CL = 100pF, Figure 3 2 µs tPHL, tPLH RL = 450Ω, CL = 100pF, Figure 3 2 µs | tPHL tPLH | RL = 450Ω, CL = 100pF, Figure 3 50 ns Transmitter Propagation Delay Data Skew mA V.10 RECEIVER Threshold Voltage VTH ∆VTH Input Hysteresis Receiver Propagation Delay Data Skew 25 100 250 15 tPHL, tPLH Figure 4 | tPHL tPLH | Figure 4 MAX3172 5 mV mV 10 15 µs MAX3174 60 120 ns MAX3172 0.5 4 µs MAX3174 5 16 ns _______________________________________________________________________________________ 3 MAX3172/MAX3174 ELECTRICAL CHARACTERISTICS (continued) MAX3172/MAX3174 +3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers ELECTRICAL CHARACTERISTICS (continued) (VCC = +3.3V ± 5%, TA = TMIN to TMAX. Typical values are at VCC = +3.3V, TA = +25°C, unless otherwise noted. See Note 2 for V+ and V- input voltage conditions.) PARAMETER SYMBOL CONDITIONS MIN TYP ±5.0 ±5.4 MAX UNITS V.28 TRANSMITTER Output Voltage Swing VO Short-Circuit Current ISC RL = 3kΩ, Figure 3 ±6.5 Open circuit, Figure 3 ±25 T4OUT = GND RL = 3kΩ, CL = 2500pF measured from +3V to -3V or -3V to +3V, Figure 3 Output Slew Rate Data Skew mA 30 V/µs SR RL = 7kΩ , CL = 150pF measured from +3V to -3V or -3V to +3V, Figure 3 Transmitter Propagation Delay 4 ±60 V 6 30 tPHL, tPLH 1 µs | tPHL tPLH | 100 ns V.28 RECEIVER Input Threshold Low VIL Input Threshold High VIH Input Hysteresis Receiver Propagation Delay Data Skew 1.1 2.0 VHYS 0.8 1.6 V 0.5 tPHL, tPLH Figure 4 | tPHL tPLH | Figure 4 MAX3172 MAX3174 5 10 V 15 200 MAX3172 0.5 MAX3174 100 V µs ns 4 µs ns Note 2: The charge pump on the MAX3171/MAX3173 can supply V+ and V- to the MAX3172/MAX3174. The V+ and V- input levels vary with the mode of chipset operation as follows: V.35/V.28 modes: +5.55V ≤ V+ ≤ +6.50V, -6.50V ≤ V- ≤ -5.45V Typical operation: V+ = +5.90V, V- = -5.80V V.10/V.11 modes: +4.20V ≤ V+ ≤ +5.0V, -4.60V ≤ V- ≤ -3.80V Typical operation: V+ = +4.60V, V- = -4.20V The MAX3171/MAX3173 are guaranteed to provide these V+/V- supply levels. 4 _______________________________________________________________________________________ +3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers V.28 60kbps TRANSMITTER WAVEFORM (3kΩ/1000pF LOAD) V.28 SLEW RATE vs. LOAD CAPACITANCE SLEW RATE (V/µs) MAX3172-01 MAX3172-02 24 22 20 18 16 RL = 3kΩ 5V +SLEW T4IN 5V/div 0 14 12 10 8 5V -SLEW 6 4 2 0 T4OUT 5V/div 0 -5V 500 0 1000 1500 2000 2500 10µs/div 3000 LOAD CAPACITANCE (pF) V.10 RISE AND FALL TIMES vs. LOAD CAPACITANCE V.10 60kbps TRANSMITTER WAVEFORM (450Ω/100pF) MAX3172-04 MAX3172-03 2.5 RISE AND FALL TIMES (µs) FALL TIME 5V 2.0 T4IN 5V/div 0 1.5 RISE TIME 1.0 T4OUT 5V/div 5V 0 0.5 -5V RL = 450Ω 0 0 500 1000 1500 2000 2500 10µs/div 3000 LOAD CAPACITANCE (pF) V.11/V.35 DIFFERENTIAL-MODE IMPEDANCE vs. COMMON-MODE VOLTAGE V.11/V.35 DIFFERENTIAL-MODE IMPEDANCE vs. TEMPERATURE 108 107 106 VCM = +7V 105 VCM = 0 104 103 102 VCM = -7V 101 110 MAX3172-06 109 DIFFERENTIAL-MODE IMPEDANCE (Ω) MAX3172-05 DIFFERENTIAL-MODE IMPEDANCE (Ω) 110 109 108 107 106 105 104 103 102 101 100 100 -10 0 10 20 30 40 50 TEMPERATURE (°C) 60 70 80 -7 -5 -3 -1 1 3 5 7 COMMON-MODE VOLTAGE (V) _______________________________________________________________________________________ 5 MAX3172/MAX3174 Typical Operating Characteristics (VCC = +3.3V (see Note 2 in Electrical Characteristics table), TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (VCC = +3.3V (see Note 2 in Electrical Characteristics table), TA = +25°C, unless otherwise noted.) V.11/V.35 DIFFERENTIAL-MODE IMPEDANCE vs. V+ V.11/V.35 DIFFERENTIAL-MODE IMPEDANCE vs. V- 104.5 104.0 103.5 103.0 4.4 4.6 4.8 5.0 104.0 103.5 5.2 5.4 -5.4 -5.2 -5.0 -4.8 -4.6 -4.4 -4.2 -4.0 -3.8 -3.6 V- (V) V.35 COMMON-MODE IMPEDANCE vs. TEMPERATURE V.35 COMMON-MODE IMPEDANCE vs. COMMON-MODE VOLTAGE 152 VCM = -2.0V 151 150 149 148 MAX3172-10 VCM = 0 153 154 COMMON-MODE IMPEDANCE (Ω) VCM = 2.0V MAX3172-09 V+ (V) 154 153 152 151 150 149 148 147 10 20 30 40 50 60 70 -2.0 -1.5 -1.0 -0.5 80 0 0.5 1.0 1.5 TEMPERATURE (°C) COMMON-MODE VOLTAGE (V) V.35 COMMON-MODE IMPEDANCE vs. V+ V.35 COMMON-MODE IMPEDANCE vs. VMAX3172-11 165 160 155 150 145 140 165 2.0 MAX3172-12 0 COMMON-MODE IMPEDANCE (Ω) -10 160 155 150 145 140 135 135 5.5 5.7 5.9 6.1 V+ (V) 6 MAX3172-08 104.5 103.0 4.2 COMMON-MODE IMPEDANCE (Ω) 105.0 DIFFERENTIAL-MODE IMPEDANCE (Ω) MAX3172-07 DIFFERENTIAL-MODE IMPEDANCE (Ω) 105.0 COMMON-MODE IMPEDANCE (Ω) MAX3172/MAX3174 +3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers 6.3 6.5 -6.6 -6.4 -6.2 -6.0 -5.8 -5.6 V- (V) _______________________________________________________________________________________ -5.4 +3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers A A R1 52Ω R1 52Ω OHMMETER S1 ON R3 127Ω S1 ON R3 127Ω S2 OFF OHMMETER S2 ON R2 52Ω R2 52Ω VCM = ±2V B VCM = ±7V OR ±2V B Figure 1. V.11 or V.35 Differential Impedance Measurement T Figure 2. V.35 Common-Mode Impedance Measurement T CL Figure 3. V.10/V.28 Driver Test Circuit R RL 15pF Figure 4. V.10/V.28 Receiver Test Circuit _______________________________________________________________________________________ 7 MAX3172/MAX3174 Test Circuits +3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers MAX3172/MAX3174 Pin Description 8 PIN NAME FUNCTION 1 M2 Mode-Select Pin (see Tables 1 and 3 for detailed information) 2 M1 Mode-Select Pin (see Tables 1 and 3 for detailed information) 3 M0 Mode-Select Pin (see Tables 1 and 3 for detailed information) 4 VCC +3.3V Supply Voltage (±5%). Bypass VCC to GND with a 0.1µF capacitor. 5 R5A Termination Network 5 Node A 6 R5B Termination Network 5 Node B 7 T4IN Transmitter CMOS Input 8 R4OUT Receiver CMOS Output 9,18, 22 GND Ground 10 R4B Termination Network 4 Node B 11 R4A Termination Network 4 Node A 12 R3C Termination Network 3 Node C 13 R3B Termination Network 3 Node B 14 R3A Termination Network 3 Node A 15 R1A Termination Network 1 Node A 16 R1B Termination Network 1 Node B 17 R1C Termination Network 1 Node C 19 R2C Termination Network 2 Node C 20 R2B Termination Network 2 Node B 21 R2A Termination Network 2 Node A 23 R4INA 24 V- 25 T4OUT 26 V+ 27 DCE/DTE 28 INVERT Inverting Receiver Input Negative Supply (connect to V- pin of MAX3171/MAX3173). Bypass V- to GND with a 0.1µF capacitor. Inverting Transmitter Output Positive Supply (connect to V+ pin of MAX3171/MAX3173). Bypass V+ to GND with a 0.1µF capacitor. DCE/DTE Mode-Select Pin. Logic level LOW selects DTE interface. See Tables 1 and 3 for detailed information. Mode-Select Pin (inverts functionality of DCE/DTE input for T4/R4). See Tables 1 and 3 for detailed information. _______________________________________________________________________________________ +3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers MAX3172/MAX3174 Table 1. Termination Mode Selection MODE V.10/RS-423 M2 0 M1 0 M0 0 DCE/DTE 0 INVERT X R1 Z R2 Z R3 Z R4 Z R5 Z RS-530A 0 0 1 0 X Z Z V.11 V.11 V.11 RS-530 0 1 0 0 X Z Z V.11 V.11 V.11 X.21 0 1 1 0 X Z Z V.11 V.11 V.11 V.35 1 0 0 0 X V.35 V.35 V.35 V.35 V.35 V.11 RS-449/V.36 1 0 1 0 X Z Z V.11 V.11 V.28/RS-232 1 1 0 0 X Z Z Z Z Z No Cable 1 1 1 0 X V.11 V.11 V.11 V.11 V.11 V.10/RS-423 0 0 0 1 X Z Z Z Z Z RS-530A 0 0 1 1 X Z Z Z V.11 V.11 RS-530 0 1 0 1 X Z Z Z V.11 V.11 X.21 0 1 1 1 X Z Z Z V.11 V.11 V.35 1 0 0 1 X V.35 V.35 V.35 V.35 V.35 RS-449/V.36 1 0 1 1 X Z Z Z V.11 V.11 V.28/RS-232 1 1 0 1 X Z Z Z Z Z No Cable 1 1 1 1 X V.11 V.11 V.11 V.11 V.11 Detailed Description The MAX3172/MAX3174 contain five software-selectable multiprotocol cable termination networks. Each network is capable of terminating V.11 transceivers (RS-422, RS530, RS-530A, RS-449, V.36, and X.21) with a 100Ω differential load, V.35 transceivers with a T-network load, or V.28 (RS-232) and V.10 transceivers (RS-423) with an open circuit load. The MAX3172/MAX3174, along with the MAX3170 and MAX3171/MAX3173, form a complete +3.3V software-selectable DTE or DCE interface port supporting V.11/RS-422, RS-530, RS-530A, V.36/RS-449, V.35, V.28/RS-232, V.10/RS-423, and X.21 serial interfaces. The MAX3172/MAX3174 also contain a multiprotocol transceiver that is software-selectable between V.10 and V.28 operation modes. This transceiver is intended as the handshake signal I/O in a DCE/DTE port application, and is designed to use V+ and V- levels generated by the MAX3171/MAX3173 charge pump. The MAX3172 features 10µs deglitching on the V.10/V.28 receiver input to allow unterminated operation. The MAX3174 is used in applications that do not require deglitching on the serial handshake signals. No-Cable Mode The MAX3172/MAX3174 enter no-cable mode when the mode-select inputs are all HIGH (M0 = M1 = M2 = 1). In this mode, the driver, receiver, and bias circuitry are disabled, and the supply current drops to less than 200µA. Table 2. Switch Configuration by Mode MODE SW1 SW2 V.35 ON ON V.11 ON OFF V.28/V.10 (Z) OFF OFF In no-cable mode, all five termination networks are placed in the V.11 mode of operation (shorting pins R_A and R_B with a 100Ω resistor). The receiver output enters a high-impedance state in no-cable mode, allowing this output line to be shared with other receivers (the receiver output has an internal pullup resistor to pull the output HIGH if not driven). Also, in no-cable mode, the transmitter output enters a high-impedance state so that this output can be shared with other devices. Cable Termination The MAX3172/MAX3174 software-selectable resistor networks are intended for use with the MAX3170 clock/data transceiver chip. The termination network is used for the V.11, V.35, and V.28 transmitters. The MAX3172/ MAX3174 provide the advantage of not having to build expensive termination networks from resistors and relays, manually changing termination modules, or building termination networks into custom cables. Each termination network can be in one of three modes: V.35, V.11, or high impedance (high-Z) as shown in Figure 5 (see Table 2). For example, in V.35 mode, all five _______________________________________________________________________________________ 9 MAX3172/MAX3174 +3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers Table 3. R4/T4 Mode-Select Table PROTOCOL M2 M1 M0 DCE/DTE INVERT T4 R4 Not Used (Default V.11) 0 0 0 0 0 Z V.10 RS-530A 0 0 1 0 0 Z V.10 RS-530 0 1 0 0 0 Z V.10 X.21 0 1 1 0 0 Z V.10 V.35 1 0 0 0 0 Z V.28 RS-449/V.36 1 0 1 0 0 Z V.10 V.28/RS-232 1 1 0 0 0 Z V.28 No Cable 1 1 1 0 0 Z Z Not Used (Default V.11) 0 0 0 1 0 V.10 Z RS-530A 0 0 1 1 0 V.10 Z RS-530 0 1 0 1 0 V.10 Z X.21 0 1 1 1 0 V.10 Z V.35 1 0 0 1 0 V.28 Z RS-449/V.36 1 0 1 1 0 V.10 Z V.28/RS-232 1 1 0 1 0 V.28 Z No Cable 1 1 1 1 0 Z Z Not Used (Default V.11) 0 0 0 0 1 V.10 Z RS-530A 0 0 1 0 1 V.10 Z RS-530 0 1 0 0 1 V.10 Z X.21 0 1 1 0 1 V.10 Z V.35 1 0 0 0 1 V.28 Z RS-449/V.36 1 0 1 0 1 V.10 Z V.28/RS-232 1 1 0 0 1 V.28 Z No Cable 1 1 1 0 1 Z Z Not Used (Default V.11) 0 0 0 1 1 Z V.10 RS-530A 0 0 1 1 1 Z V.10 RS-530 0 1 0 1 1 Z V.10 X.21 0 1 1 1 1 Z V.10 V.35 1 0 0 1 1 Z V.28 RS-449/V.36 1 0 1 1 1 Z V.10 V.28/RS-232 1 1 0 1 1 Z V.28 No Cable 1 1 1 1 1 Z Z networks are configured to provide 100Ω differential impedance and 150Ω common-mode impedance to terminate the MAX3170 V.35 transmitter outputs and receiver inputs. Termination Mode Selection The mode-select pins M0, M1, M2, and DCE/DTE control the state of the five termination networks (Table 1). The mode-select table of the MAX3172/MAX3174 is compatible with the MAX3170 mode-select table so that the M0, 10 M1, M2, and DCE/DTE pins can be connected to the corresponding pins on the MAX3170. For example, M2 = 1, M1 = 0, M0 = 0 corresponds to V.35 mode for both the MAX3172/MAX3174 and the MAX3170 clock/data transceiver chip. R4/T4 Mode Selection The MAX3172/MAX3174 include a transceiver for use in applications requiring an extra serial handshake signal (for example, local loopback). The transceiver can be ______________________________________________________________________________________ +3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers MAX3172/MAX3174 *NODE C IS PROVIDED IN NETWORKS 1,2,3. A A A R1 52Ω R1 52Ω R1 52Ω C* C* S1 ON C* S1 OFF S1 ON R3 127Ω R3 127Ω S2 OFF R3 127Ω S2 ON R2 52Ω S2 OFF R2 52Ω B R2 52Ω B B V.11 MODE V.35 MODE HIGH-Z MODE Figure 5. MAX3172/MAX3174 Termination Network Configurations BALANCED INTERCONNECTING CABLE GENERATOR LOAD CABLE RECEIVER TERMINATION A′ A 100Ω MIN B B′ C C′ Figure 6. Typical V.11 Interface configured for V.10 or V.28 operation as a driver or receiver (Table 3). This mode-selection table is compatible for use with the MAX3170 (clock/data transceiver) and the MAX3171/MAX3173 (control transceiver). For example, if X.21 mode is selected in DCE mode (M2 = 0, M1 = 1, M0 = 1, and DCE/DTE = 1), the MAX3170, MAX3171/MAX3173, and MAX3172/MAX3174 transceivers will all be placed in X.21 DCE mode. threshold is between +25mV and +250mV. If the V.10 receiver input voltage is less than +25mV, R4OUT is logic HIGH. If the V.10 receiver input is greater than +250mV, R4OUT is logic LOW. The V.28 receiver threshold is between +0.8V and +2.0V. If the V.28 receiver input voltage is less than +0.8V, R4OUT is logic HIGH. If the receiver input is greater than +2.0V, R4OUT is logic LOW. If the driving transmitter is disabled or disconnected, the receiver’s input voltage is pulled to zero by its internal termination. With the receiver thresholds of the MAX3172/MAX3174, this results in a logic HIGH. Applications Information Fail-Safe Older multiprotocol cable termination implementations have been constructed using expensive relays with discrete resistors, custom cables with built-in termination, or complex circuit board configurations to route signals to the correct termination. The MAX3172/MAX3174 provide a simple solution to this termination problem. All required termination configurations are software selectable using four mode-control input pins (M2, M1, M0, and DCE/DTE). The MAX3172/MAX3174 guarantee a logic HIGH receiver output when the receiver input is shorted to GND or when it is connected to a terminated transmission line with the driver disabled. The V.10 receiver For high-speed data transmission, the V.11 specification recommends terminating the cable at the receiver V.11 Termination ______________________________________________________________________________________ 11 MAX3172/MAX3174 +3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers A′ A MAX3170 R5 30kΩ R1 52Ω R8 5kΩ MAX3172 MAX3174 R6 10kΩ RECEIVER S3 S1 R3 127Ω S2 R7 10kΩ R2 52Ω B′ R4 30kΩ B C′ GND Figure 7. V.11 Termination and Internal Resistance Networks BALANCED INTERCONNECTING CABLE GENERATOR A 50Ω LOAD A′ 125Ω CABLE TERMINATION 125Ω 50Ω RECEIVER 50Ω 50Ω B B′ C C′ Figure 8. Typical V.35 Interface with a minimum of a 100Ω resistor (Figure 6). This resistor, although not required, prevents reflections from corrupting transmitted data. In Figure 7, the MAX3172/MAX3174 are used to terminate the V.11 receiver. Internal to the MAX3172/ MAX3174, S1 is closed and S2 is open to present a 104Ω typical differential resistance and high-Z common-mode impedance. S3 opens to disable the MAX3170’s internal V.28 termination. The V.11 specification allows for signals with commonmode variations of ±7V with differential signal amplitudes from 2V to 6V. Also, data rates may be as high as 12 10Mbps. The MAX3172/MAX3174 maintain steady termination impedance between 100Ω and 110Ω over these conditions. V.35 Termination Figure 8 shows a standard V.35 interface. The generator and the load must both present a 100Ω ±10Ω differential impedance and a 150Ω ±15Ω common-mode impedance (as shown by the resistive T-networks in Figure 8). The V.35 driver generates a current output (typically ±11mA) that develops an output voltage between 440mV and 660mV across the load termination networks. ______________________________________________________________________________________ +3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers MAX3172/MAX3174 A′ A MAX3170 R5 30kΩ R1 52Ω R8 5kΩ MAX3172 MAX3174 R6 10kΩ RECEIVER S3 S1 R3 127Ω S2 R7 10kΩ R2 52Ω B′ R4 30kΩ B C′ GND Figure 9. V.35 Termination and Internal Resistance Networks A DRIVER The V.35 specification allows for ±4V of ground difference between the V.35 generator and V.35 load. The V.35 data rates may be as high as 10Mbps. The MAX3172/MAX3174 maintain correct terminal impedances over these conditions. R1 52Ω MAX3172 MAX3174 S1 R3 127Ω V.35 EMI Reduction S2 R2 52Ω R_C C1 100pF tion resistor, internal to the MAX3170, is disabled by opening S3 to avoid interference with the T-network impedance. B C(GND) Figure 10. V.35 Driver In Figure 9, the MAX3172/MAX3174 are used to implement the resistive T-network that is needed to properly terminate the V.35 driver and receiver. Internal to the MAX3172/MAX3174, S1 and S2 are closed to connect the T-network resistors to the circuit. The V.28 termina- For applications where EMI reduction is especially important, the MAX3172/MAX3174 termination networks provide a pin for shunting common-mode driver currents to GND (Figure 10). Mismatches between A and B driver output propagation delays create a common-mode disturbance on the cable. This commonmode energy can be shunted to GND by placing a 100pF capacitor (C1 to GND) from the center point of the T-network termination (R1C, R2C, and R3C). V.28 Termination Most industry-standard V.28 receivers (including the MAX3170) do not require external termination because the receiver includes an internal 5kΩ termination resistor. When the MAX3172/MAX3174 are placed in V.28 mode, all five of the termination networks are placed in a high-Z mode. In high-Z mode, the MAX3172/ MAX3174 termination networks will not interfere with the MAX3170's internal 5kΩ termination. ______________________________________________________________________________________ 13 MAX3172/MAX3174 +3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers A′ A MAX3170 R5 30kΩ R1 52Ω R8 5kΩ MAX3172 MAX3174 R6 10kΩ RECEIVER S3 S1 R3 127Ω S2 R7 10kΩ R2 52Ω B′ R4 30kΩ B C′ GND Figure 11. V.28 Termination and Internal Resistance Networks GENERATOR UNBALANCED INTERCONNECTING CABLE LOAD CABLE TERMINATION A A′ C C′ RECEIVER V.10 Interface Figure 12. Typical V.28 and V.10 Interface IZ -10V 3.25mA -3V VZ +10V +3V -3.25mA Figure 13. V.10 Receiver Input Impedance In Figure 11, the MAX3170 and MAX3172/MAX3174 are placed in V.28 mode. Switches S1 and S2 are opened on the MAX3172/MAX3174 to place the network in highZ mode. Switch S3 is closed on the MAX3170 to enable the 5kΩ terminating resistor. V.28 Interface The V.28 interface is an unbalanced single-ended interface (Figure 12). The V.28 driver generates a minimum of ±5V across the load impedance between A' and C'. 14 The V.28 receiver specification calls for input trip points at ±3V. To aid in rejecting system noise, the MAX3170 V.28 receiver has a typical hysteresis of 0.5V. Also, the MAX3172/MAX3174 have more tightly specified input trip points to guarantee fail-safe operation (see FailSafe). The MAX3172/MAX3174 V.28 receiver provides an internal 5kΩ termination resistance. The V.10 interface (Figure 12) is an unbalanced singleended interface capable of driving a 450Ω load. The V.10 driver generates a minimum voltage of ±4V (VODO) across A' and C' when unloaded and a minimum voltage of ±0.9 ✕ VODO when loaded with 450Ω. The V.10 receiver input trip threshold is defined between +300mV and -300mV with input impedance characteristics shown in Figure 13. The MAX3172/MAX3174 V.10 mode receiver has a threshold between +25mV and +250mV to ensure that the receiver has proper fail-safe operation (see FailSafe). To aid in rejecting system noise, the MAX3172/ MAX3174 V.10 receiver has a typical hysteresis of 15mV. Switch S3 in Figure 14 is open in V.10 mode to disable the 5kΩ V.28 termination at the receiver input. Receiver Glitch Rejection To allow operation in an unterminated or otherwise noisy system, the MAX3172 features 10µs of receiver input glitch rejection. The glitch-rejection circuitry blocks the reception of high-frequency noise with a bit period less than 5µs while receiving low-frequency signals with a bit period greater than 15µs, allowing glitchfree operation in unterminated systems at up to 64kbps. ______________________________________________________________________________________ +3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers A MAX3172 MAX3174 R5 30kΩ R8 5kΩ R6 10kΩ Complete Multiprotocol X.21 Interface RECEIVER S3 R7 10kΩ R4 30kΩ A complete DTE-to-DCE interface operating in X.21 mode is shown in Figure 16. The MAX3172/MAX3174 terminate the V.11 clock and data signals, and its transceiver carries the local loopback (LL) signal. The MAX3170 carries the clock and data signals, and the MAX3171/MAX3173 carry the control signals. The control signals generally do not require external termination. Compliance Testing A European Standard EN45001 test report is available for the MAX3170–MAX3174 chipset. A copy of the test report is available from Maxim upon request. C′ GND Figure 14. V.10 Internal Resistance Networks The MAX3174 does not have this glitch rejection and can be operated at frequencies up to 240kbps if properly terminated. DCE vs. DTE Operation Figure 15 illustrates a DCE or DTE controller-selectable interface. The DCE/DTE input switches the MAX3172/ MAX3174s’ mode of operation. Logic high selects DCE, which enables driver 4 on the MAX3172/MAX3174 (INVERT = 0), driver 3 on the MAX3171/MAX3173, and driver 3 on the MAX3170. A logic low selects DTE, which enables receiver 4 on the MAX3172/MAX3174 (INVERT = 0), receiver 1 on the MAX3171/MAX3173, and receiver 1 on the MAX3170. ______________________________________________________________________________________ 15 MAX3172/MAX3174 A′ This application requires only one DB-25 connector. See Figure 15 for complete signal routing in DCE and DTE modes. For example, driver 4 routes the LL(DCE) signal to pin 18 in DCE mode, while in DTE mode, receiver 4 routes pin 18 to the LL(DTE) signal. CTS(DTE) RTS(DCE) DSR(DTE) DTR(DCE) RXD(DTE) TXD(DCE) LL(DTE) RXC(DTE) LL(DCE) SCTE(DCE) DTR(DTE) DSR(DCE) RTS(DTE) DCD(DTE) CTS(DCE) DCD(DCE) SCTE(DTE) RXC(DCE) TXC(DTE) TXD(DTE) TXC(DCE) RXD(DCE) MAX3171 MAX3173 R3 R2 R1 D3 D2 D1 M0 M1 M2 DCE/DTE MAX3172 MAX3174 R4 R3 R2 16 3 9 17 R1 D3 D2 D1 D4 MAX3170 M0 M1 M2 DCE/DTE MAX3172/MAX3174 +3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers Figure 15. Multiprotocol DCE/DTE Port 16 ______________________________________________________________________________________ TXD B TXD A RXD B RXD A TXC B TXC A TXC B TXC A RXC B SCTE B RXC A SCTE A RXD B RXD A RXC B RXC A DB-25 CONNECTOR 12 15 11 24 14 2 TXD B TXD A SCTE B SCTE A SG LL A 7 18 LL A 1 SHIELD RTS B RTS A CTS B CTS A DTR B DTR A DCD B DCD A 23 20 19 4 DSR B DSR A DSR B DSR A DCD B DCD A 22 6 DTR B DTR A 10 8 DCE RTS B RTS A 13 5 DTE CTS B CTS A M0 M1 M2 DCE/DTE M0 M1 M2 DCE/DTE +3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers SERIAL CONTROLLER MAX3170 DCE MAX3172 MAX3174 MAX3172 MAX3174 TXD D1 TXD SCTE D2 SCTE 103Ω 103Ω D3 TXC R1 RXC R2 RXD R3 MAX3170 SERIAL CONTROLLER R3 TXD R2 SCTE R1 103Ω 103Ω 103Ω D4 LL MAX3172/MAX3174 DTE TXC D3 TXC RXC D2 RXC RXD LL D1 RXD R4 R4 LL D4 MAX3171 MAX3173 MAX3171 MAX3173 RTS D1 RTS R3 RTS DTR D2 DTR R2 DTR D3 R1 DCD R1 DCD D3 DCD DSR R2 DSR D2 DSR CTS R3 CTS D1 CTS Figure 16. DCE-TO-DTE X.21 Interface ______________________________________________________________________________________ 17 +3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers MAX3172/MAX3174 Pin Configuration Chip Information TRANSISTOR COUNT: 2506 TOP VIEW M2 1 28 INVERT M1 2 27 DCE/DTE M0 3 26 V+ VCC 4 25 T4OUT R5A 5 R5B 6 24 V- MAX3172 MAX3174 23 R4INA T4IN 7 22 GND R4OUT 8 21 R2A GND 9 20 R2B R4B 10 19 R2C R4A 11 18 GND R3C 12 17 R1C R3B 13 16 R1B R3A 14 15 R1A 28 SSOP 18 ______________________________________________________________________________________ +3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers SSOP.EPS Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 19 © 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. MAX3172/MAX3174 Package Information