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19-1801; Rev 1; 1/01
+3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers
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 100 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 10s 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.
Features
o Industry's First +3.3V Multiprotocol Termination Networks and Transceivers o Certified TBR-1 and TBR-2 Compliant (NET1 and NET2) o Support V.28 (RS-232), V.11 (RS-422, RS-530, RS530A, RS-449, V.36, and X.21), V.10 and V.35 o 3V/5V Logic-Compatible I/O o Software-Selectable DTE/DCE o Replace Discrete Resistor Termination Networks and Expensive Relays o 10s Receiver Input Deglitching (MAX3172 only) o Available in Small 28-Pin SSOP Package o Transmitter Output Fault Protected to 15V, Tolerates Cable Miswiring
MAX3172/MAX3174
Ordering Information
PART MAX3172CAI MAX3174CAI TEMP. RANGE 0C to +70C 0C to +70C PIN-PACKAGE 28 SSOP 28 SSOP
________________________Applications
Data Networking CSU and DSU Data Routers
CTS
PCI Cards Telecommunications
Pin Configuration appears at end of data sheet.
Typical Operating Circuit
DSR DCD DTR RTS LL RXD RXC TXC SCTE TXD
MAX3171 MAX3173
R3
R2
R1
D3
D2
D1 MAX3172 MAX3174
R3
R2
R1
D3
D2
D1 MAX3170
R4 D4
13 5 CTS B CTS A
10 8 DSR B DSR A
22 6 DCD B DCD A
23 20 19 4 DTR B DTR A RTS B RTS A
1 SHIELD
7 SG DB-25 CONNECTOR
18 LL A
16 3
9 17
12 15 11 24 14 2 SCTE B SCTE A TXC B TXC A TXD B TXD A
________________________________________________________________ Maxim Integrated Products
RXD B RXD A RXC B RXC A
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.
+3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers MAX3172/MAX3174
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 = +70C) 28-Pin SSOP (derate 9.52mW/C above +70C) ........762mW Operating Temperature Range MAX3172CAI/MAX3174CAI ...............................0C to +70C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
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 = +25C, unless otherwise noted. See Note 2 for V+ and V- input voltage conditions.)
PARAMETER DC CHARACTERISTICS Supply Current (Digital Inputs = GND or VCC) V+ Supply Current (T4IN = GND) ICC All modes V.10 receiver inactive All modes V.10 receiver active No-cable mode V.10/V.11/V.28/V.35 modes unloaded V.10/V.11 modes T4OUT loaded V.28/V.35 modes T4OUT loaded No-cable mode V- Supply Current (T4IN = VCC) IVV.10/V.11/V.28/V.35 modes unloaded V.10/V.11 modes T4OUT loaded V.28/V.35 modes T4OUT loaded TERMINATOR NETWORKS (R_A, R_B) Differential-Mode Impedance V.35 Mode Common-Mode Impedance V.35 Mode Differential-Mode Impedance V.11 Mode Network OFF Impedance IZ Figure 1, -2V VCM +2V Figure 2, -2V VCM +2V Figure 1, -7V VCM +7V Switches open, -15V VA +15V, VB = VA, VB = GND or VB floating 90 135 100 50 104 153 104 150 110 165 110 k 80 400 0.2 0.5 11.0 3.0 -0.4 -0.8 -11.0 -3.0 200 750 1.0 2.5 14.0 5.0 -1.0 -2.5 -14.0 -5.0 mA mA A SYMBOL CONDITIONS MIN TYP MAX UNITS
IV+
LOGIC INPUTS (M0, M1, M2, INVERT, DCE/DTE, T4IN) Input High Voltage Input Low Voltage Logic Input Current VIH VIL IIH, IIL VIN = VCC or GND 2.0 0.8 1 V V A
2
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+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 = +25C, unless otherwise noted. See Note 2 for V+ and V- input voltage conditions.)
PARAMETER LOGIC OUTPUT (R4OUT) Output High Voltage Output Low Voltage Rise or Fall Time Output Leakage Current (Receiver Output Three-Stated) TRANSMITTER OUTPUT (T4OUT) Output Leakage Current Data Rate RECEIVER INPUT (R4INA) Receiver Glitch Rejection (MAX3172 only) Receiver Input Resistance Data Rate V.10 TRANSMITTER Output Voltage Swing Loaded Output Voltage Swing Short-Circuit Current Rise or Fall Time Transmitter Propagation Delay Data Skew V.10 RECEIVER Threshold Voltage Input Hysteresis Receiver Propagation Delay Data Skew VTH VTH tPHL, tPLH | tPHL tPLH | Figure 4 Figure 4 MAX3172 MAX3174 MAX3172 MAX3174 5 25 100 15 10 60 0.5 5 15 120 4 16 250 mV mV s ns s ns VODO VODL ISC tr, tf tPHL, tPLH | tPHL tPLH | RL = 3.9k, Figure 3 RL = 450, Figure 3 T4OUT = GND 10% to 90%, RL = 450, CL = 100pF, Figure 3 RL = 450, CL = 100pF, Figure 3 RL = 450, CL = 100pF, Figure 3 4.0 0.9 x VODO 100 2 2 50 150 4.4 6.0 V V mA s s ns RIN Minimum pulse width passed Maximum pulse width rejected V.10 enabled, -10V VR4INA +10V V.28 enabled, -15V VR4INA +15V MAX3172 MAX3174 20 3 40 5 64 240 7 5 15 s k kbps IZ -0.25V < VT4OUT < +0.25V, power-off or no-cable mode V.10/V.28 -100 240 100 A kbps VOH VOL tr, tf ISOURCE = 1.0mA ISINK = 1.6mA 10% to 90%, CL = 15pF R4OUT = GND R4OUT = VCC 30 15 50 0.1 100 1 VCC - 1.0 0.4 V V ns A SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX3172/MAX3174
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+3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers MAX3172/MAX3174
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +3.3V 5%, TA = TMIN to TMAX. Typical values are at VCC = +3.3V, TA = +25C, unless otherwise noted. See Note 2 for V+ and V- input voltage conditions.)
PARAMETER V.28 TRANSMITTER Output Voltage Swing Short-Circuit Current VO ISC RL = 3k, Figure 3 Open circuit, Figure 3 T4OUT = GND RL = 3k, CL = 2500pF measured from +3V to -3V or -3V to +3V, Figure 3 Output Slew Rate SR RL = 7k , CL = 150pF measured from +3V to -3V or -3V to +3V, Figure 3 Transmitter Propagation Delay Data Skew V.28 RECEIVER Input Threshold Low Input Threshold High Input Hysteresis Receiver Propagation Delay Data Skew VIL VIH VHYS tPHL, tPLH | tPHL tPLH | Figure 4 Figure 4 MAX3172 MAX3174 MAX3172 MAX3174 5 2.0 1.1 1.6 0.5 10 200 0.5 100 4 15 0.8 V V V s ns s ns tPHL, tPLH | tPHL tPLH | 6 1 100 30 s ns 4 25 5.0 5.4 6.5 60 30 V/s V mA SYMBOL CONDITIONS MIN TYP MAX UNITS
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.
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+3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers
Typical Operating Characteristics
(VCC = +3.3V (see Note 2 in Electrical Characteristics table), TA = +25C, unless otherwise noted.)
V.28 60kbps TRANSMITTER WAVEFORM (3k/1000pF LOAD)
MAX3172-02
MAX3172/MAX3174
V.28 SLEW RATE vs. LOAD CAPACITANCE
24 22 20 18 16 14 12 10 8 6 4 2 0 0 500 -SLEW 5V 0 -5V 2000 RL = 3k +SLEW
MAX3172-01
5V 0
T4IN 5V/div
SLEW RATE (V/s)
T4OUT 5V/div
1000
1500
2500
3000
10s/div
LOAD CAPACITANCE (pF)
V.10 RISE AND FALL TIMES vs. LOAD CAPACITANCE
MAX3172-03
V.10 60kbps TRANSMITTER WAVEFORM (450/100pF)
MAX3172-04
2.5 FALL TIME RISE AND FALL TIMES (s) 2.0
5V 0
T4IN 5V/div
1.5 RISE TIME 1.0 5V 0 0.5 -5V RL = 450 0 0 500 1000 1500 2000 2500 3000 10s/div LOAD CAPACITANCE (pF) T4OUT 5V/div
V.11/V.35 DIFFERENTIAL-MODE IMPEDANCE vs. TEMPERATURE
DIFFERENTIAL-MODE IMPEDANCE () DIFFERENTIAL-MODE IMPEDANCE () 109 108 107 106 105 104 103 102 101 100 -10 0 10 20 30 40 50 60 70 80 TEMPERATURE (C) VCM = -7V VCM = +7V VCM = 0
MAX3172-05
V.11/V.35 DIFFERENTIAL-MODE IMPEDANCE vs. COMMON-MODE VOLTAGE
109 108 107 106 105 104 103 102 101 100 -7 -5 -3 -1 1 3 5 7 COMMON-MODE VOLTAGE (V)
MAX3172-06
110
110
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+3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers MAX3172/MAX3174
Typical Operating Characteristics (continued)
(VCC = +3.3V (see Note 2 in Electrical Characteristics table), TA = +25C, unless otherwise noted.)
V.11/V.35 DIFFERENTIAL-MODE IMPEDANCE vs. V+
MAX3172-07
V.11/V.35 DIFFERENTIAL-MODE IMPEDANCE vs. VDIFFERENTIAL-MODE IMPEDANCE ()
MAX3172-08
105.0 DIFFERENTIAL-MODE IMPEDANCE ()
105.0
104.5
104.5
104.0
104.0
103.5
103.5
103.0 4.2 4.4 4.6 4.8 V+ (V) 5.0 5.2 5.4
103.0 -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
VCM = 2.0V VCM = 0
MAX3172-09
V.35 COMMON-MODE IMPEDANCE vs. COMMON-MODE VOLTAGE
MAX3172-10
154 COMMON-MODE IMPEDANCE () 153 152 151 150 149 148 147 -10 0 10 20 30 40
154 COMMON-MODE IMPEDANCE () 153 152 151 150 149 148
VCM = -2.0V
50
60
70
80
-2.0 -1.5 -1.0 -0.5
0
0.5
1.0
1.5
2.0
TEMPERATURE (C)
COMMON-MODE VOLTAGE (V)
V.35 COMMON-MODE IMPEDANCE vs. V+
MAX3172-11
V.35 COMMON-MODE IMPEDANCE vs. VMAX3172-12
165 COMMON-MODE IMPEDANCE () 160 155 150 145 140 135 5.5 5.7 5.9 V+ (V) 6.1 6.3
165 COMMON-MODE IMPEDANCE () 160 155 150 145 140 135
6.5
-6.6
-6.4
-6.2
-6.0 V- (V)
-5.8
-5.6
-5.4
6
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+3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers
Test Circuits
A A R1 52 R1 52 OHMMETER S1 ON R3 127 S2 OFF OHMMETER R2 52 R2 52 S2 ON S1 ON R3 127
MAX3172/MAX3174
B VCM = 7V OR 2V
VCM = 2V B
Figure 1. V.11 or V.35 Differential Impedance Measurement
Figure 2. V.35 Common-Mode Impedance Measurement
T
T
R
CL
RL
15pF
Figure 3. V.10/V.28 Driver Test Circuit
Figure 4. V.10/V.28 Receiver Test Circuit
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+3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers MAX3172/MAX3174
Pin Description
PIN 1 2 3 4 5 6 7 8 9,18, 22 10 11 12 13 14 15 16 17 19 20 21 23 24 25 26 27 28 NAME M2 M1 M0 VCC R5A R5B T4IN R4OUT GND R4B R4A R3C R3B R3A R1A R1B R1C R2C R2B R2A R4INA VT4OUT V+ DCE/DTE INVERT FUNCTION Mode-Select Pin (see Tables 1 and 3 for detailed information) Mode-Select Pin (see Tables 1 and 3 for detailed information) Mode-Select Pin (see Tables 1 and 3 for detailed information) +3.3V Supply Voltage (5%). Bypass VCC to GND with a 0.1F capacitor. Termination Network 5 Node A Termination Network 5 Node B Transmitter CMOS Input Receiver CMOS Output Ground Termination Network 4 Node B Termination Network 4 Node A Termination Network 3 Node C Termination Network 3 Node B Termination Network 3 Node A Termination Network 1 Node A Termination Network 1 Node B Termination Network 1 Node C Termination Network 2 Node C Termination Network 2 Node B Termination Network 2 Node A Inverting Receiver Input Negative Supply (connect to V- pin of MAX3171/MAX3173). Bypass V- to GND with a 0.1F capacitor. Inverting Transmitter Output Positive Supply (connect to V+ pin of MAX3171/MAX3173). Bypass V+ to GND with a 0.1F 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.
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+3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers MAX3172/MAX3174
Table 1. Termination Mode Selection
MODE V.10/RS-423 RS-530A RS-530 X.21 V.35 RS-449/V.36 V.28/RS-232 No Cable V.10/RS-423 RS-530A RS-530 X.21 V.35 RS-449/V.36 V.28/RS-232 No Cable M2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 M1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 M0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 DCE/DTE 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 INVERT X X X X X X X X X X X X X X X X R1 Z Z Z Z V.35 Z Z V.11 Z Z Z Z V.35 Z Z V.11 R2 Z Z Z Z V.35 Z Z V.11 Z Z Z Z V.35 Z Z V.11 R3 Z V.11 V.11 V.11 V.35 V.11 Z V.11 Z Z Z Z V.35 Z Z V.11 R4 Z V.11 V.11 V.11 V.35 V.11 Z V.11 Z V.11 V.11 V.11 V.35 V.11 Z V.11 R5 Z V.11 V.11 V.11 V.35 V.11 Z V.11 Z V.11 V.11 V.11 V.35 V.11 Z 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 100 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 10s 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.
Table 2. Switch Configuration by Mode
MODE V.35 V.11 V.28/V.10 (Z) SW1 ON ON OFF SW2 ON 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 100 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
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 200A.
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+3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers MAX3172/MAX3174
Table 3. R4/T4 Mode-Select Table
PROTOCOL Not Used (Default V.11) RS-530A RS-530 X.21 V.35 RS-449/V.36 V.28/RS-232 No Cable Not Used (Default V.11) RS-530A RS-530 X.21 V.35 RS-449/V.36 V.28/RS-232 No Cable Not Used (Default V.11) RS-530A RS-530 X.21 V.35 RS-449/V.36 V.28/RS-232 No Cable Not Used (Default V.11) RS-530A RS-530 X.21 V.35 RS-449/V.36 V.28/RS-232 No Cable M2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 M1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 M0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 DCE/DTE 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 INVERT 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 T4 Z Z Z Z Z Z Z Z V.10 V.10 V.10 V.10 V.28 V.10 V.28 Z V.10 V.10 V.10 V.10 V.28 V.10 V.28 Z Z Z Z Z Z Z Z Z R4 V.10 V.10 V.10 V.10 V.28 V.10 V.28 Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z V.10 V.10 V.10 V.10 V.28 V.10 V.28 Z
networks are configured to provide 100 differential impedance and 150 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
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+3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers MAX3172/MAX3174
*NODE C IS PROVIDED IN NETWORKS 1,2,3. A A A
R1 52 C* S1 ON R3 127 S2 OFF R2 52
R1 52 C* S1 ON R3 127 S2 ON R2 52
R1 52 C* S1 OFF R3 127 S2 OFF R2 52
B
B
B
V.11 MODE
V.35 MODE
HIGH-Z MODE
Figure 5. MAX3172/MAX3174 Termination Network Configurations
GENERATOR
BALANCED INTERCONNECTING CABLE
LOAD CABLE RECEIVER TERMINATION A 100 MIN
A
B C
B C
Figure 6. Typical V.11 Interface
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.
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.
Applications Information
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).
Fail-Safe
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
V.11 Termination
For high-speed data transmission, the V.11 specification recommends terminating the cable at the receiver
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+3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers MAX3172/MAX3174
A A R5 30k R1 52
MAX3170
MAX3172 MAX3174
R8 5k
R6 10k
RECEIVER
S1 S2
S3 R3 127
R2 52 B B R4 30k
R7 10k
C GND
Figure 7. V.11 Termination and Internal Resistance Networks
GENERATOR
BALANCED INTERCONNECTING CABLE A A CABLE TERMINATION
LOAD RECEIVER
50
125
125
50
50 B C B C
50
Figure 8. Typical V.35 Interface
with a minimum of a 100 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 104 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
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10Mbps. The MAX3172/MAX3174 maintain steady termination impedance between 100 and 110 over these conditions.
V.35 Termination
Figure 8 shows a standard V.35 interface. The generator and the load must both present a 100 10 differential impedance and a 150 15 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.
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+3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers MAX3172/MAX3174
A A R5 30k R1 52
MAX3170
MAX3172 MAX3174
R8 5k
R6 10k
RECEIVER
S1
S3 R3 127 S2 R2 52 R7 10k B R4 30k
B
C GND
Figure 9. V.35 Termination and Internal Resistance Networks
A
tion resistor, internal to the MAX3170, is disabled by opening S3 to avoid interference with the T-network impedance. 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.
DRIVER
MAX3172 MAX3174
R1 52
R3 127 S2
S1
V.35 EMI Reduction
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).
R2 52 R_C C1 100pF C(GND)
B
V.28 Termination
Most industry-standard V.28 receivers (including the MAX3170) do not require external termination because the receiver includes an internal 5k 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 5k termination.
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-
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+3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers MAX3172/MAX3174
A A R5 30k R1 52
MAX3170
MAX3172 MAX3174
R8 5k
R6 10k
RECEIVER
S1 S2
S3 R3 127
R2 52 B B R4 30k
R7 10k
C GND
Figure 11. V.28 Termination and Internal Resistance Networks
UNBALANCED INTERCONNECTING CABLE
GENERATOR
LOAD CABLE TERMINATION A
RECEIVER
A
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 5k termination resistance.
C
C
V.10 Interface
The V.10 interface (Figure 12) is an unbalanced singleended interface capable of driving a 450 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 450. 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 5k V.28 termination at the receiver input.
Figure 12. Typical V.28 and V.10 Interface
IZ 3.25mA
-10V
-3V +3V VZ +10V
-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 5k terminating resistor.
Receiver Glitch Rejection
To allow operation in an unterminated or otherwise noisy system, the MAX3172 features 10s of receiver input glitch rejection. The glitch-rejection circuitry blocks the reception of high-frequency noise with a bit period less than 5s while receiving low-frequency signals with a bit period greater than 15s, allowing glitchfree operation in unterminated systems at up to 64kbps.
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'.
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+3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers
A A R5 30k R8 5k R6 10k
MAX3172 MAX3174
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.
MAX3172/MAX3174
Complete Multiprotocol X.21 Interface
RECEIVER
S3
R7 10k R4 30k
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.
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+3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers MAX3172/MAX3174
CTS(DTE) RTS(DCE) DSR(DTE) DTR(DCE) DTR(DTE) DSR(DCE) RTS(DTE) DCD(DTE) CTS(DCE) DCD(DCE) MAX3172 MAX3174 M0 M1 M2 DCE/DTE MAX3171 MAX3173 R3 R2 R1 D3 D2 D1 R4 D4 R3 R2 R1 D3 D2 D1 RXD(DTE) TXD(DCE) LL(DTE) RXC(DTE) LL(DCE) SCTE(DCE) SCTE(DTE) RXC(DCE) TXC(DTE) TXD(DTE) TXC(DCE) RXD(DCE)
MAX3170 M0 M1 M2 DCE/DTE M0 M1 M2 DCE/DTE
M0 M1 M2 DCE/DTE
13 5 DTE CTS B CTS A
10 8 DSR B DSR A
22 6 DCD B DCD A
23 20 19 4 DTR B DTR A RTS B RTS A
1 SHIELD
7 18 SG LL A
16 3
9 17
12 15 11 24 14 2 TXC B TXC A RXC B SCTE B RXC A SCTE A TXD B TXD A RXD B RXD A
TXD B TXD A SCTE B SCTE A
DCE RTS B RTS A
DTR B DTR A
DSR B DSR A
DCD B DCD A
CTS B CTS A
LL A
Figure 15. Multiprotocol DCE/DTE Port
16
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TXC B TXC A
DB-25 CONNECTOR
RXD B RXD A RXC B RXC A
+3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers MAX3172/MAX3174
DTE SERIAL CONTROLLER
MAX3170 MAX3172 MAX3174 MAX3172 MAX3174
DCE
MAX3170
SERIAL CONTROLLER
TXD SCTE
D1
TXD SCTE
103 103
R3
TXD SCTE
D2 D3
R2 R1
TXC RXC
R1 R2
103 103
TXC RXC RXD LL
D3 D2
TXC RXC
RXD LL
R3 D4
103
D1 R4 D4
RXD LL
R4
MAX3171 MAX3173
MAX3171 MAX3173
RTS DTR
D1 D2 D3
RTS DTR
R3 R2 R1
RTS DTR
DCD DSR
R1 R2
DCD DSR CTS
D3 D2
DCD DSR
CTS
R3
D1
CTS
Figure 16. DCE-TO-DTE X.21 Interface
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+3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers MAX3172/MAX3174
Pin Configuration
TOP VIEW
M2 1 M1 2 M0 3 VCC 4 R5A 5 R5B 6 T4IN 7 R4OUT 8 GND 9 R4B 10 R4A 11 R3C 12 R3B 13 R3A 14 28 INVERT 27 DCE/DTE 26 V+ 25 T4OUT 24 V-
Chip Information
TRANSISTOR COUNT: 2506
MAX3172 MAX3174
23 R4INA 22 GND 21 R2A 20 R2B 19 R2C 18 GND 17 R1C 16 R1B 15 R1A
28 SSOP
18
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+3.3V Multiprotocol Software-Selectable Cable Terminators and Transceivers
Package Information
SSOP.EPS
MAX3172/MAX3174
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 (c) 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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