General Description
The MAX3171/MAX3173 are three-driver/three-receiver
multiprotocol transceivers that operate from a single
+3.3V supply. The MAX3171/MAX3173, along with the
MAX3170 and MAX3172/MAX3174, form a complete
software-selectable data terminal equipment (DTE) or
data communications equipment (DCE) interface port
that supports V.28 (RS-232) and V.10/V.11 (RS-449,
V.36, EIA-530, EIA-530-A, X.21, RS-423) protocols. The
MAX3171/MAX3173 transceivers carry the serial inter-
face control signaling; the MAX3170 transceivers carry
the clock and data signals. The MAX3172/
MAX3174 have an extra transceiver for applications
requiring four transceivers for control signaling.
An internal charge pump and proprietary low-dropout
transmitter output stage allow V.28, V.11, and V.10
compliant operation from a single +3.3V supply. A no-
cable mode is entered when all mode pins (M0, M1,
and M2) are pulled high or left unconnected. In no-
cable mode, supply current decreases to 2mA and all
transmitter and receiver outputs are disabled (high
impedance). Short-circuit limiting and thermal-shut-
down circuits protect the drivers against excessive
power dissipation.
The MAX3171 features 10µs deglitching on the
V.10/V.11/V.28 receiver inputs. The MAX3173 is avail-
able for applications that do not require deglitching on
the serial handshake signals.
These parts require only four surface-mount capacitors
for charge-pump operation in addition to supply
bypassing.
Features
♦Industry’s First +3.3V Multiprotocol Transceiver
♦Certified TBR-1 and TBR-2 Compliant
(NET1 and NET2)
♦Supports V.28 (RS-232) and V.10/V.11 (RS-449,
V.36, EIA-530, EIA-530-A, X.21, RS-423) Protocols
♦3V/5V Logic Compatibility
♦Software-Selectable DCE/DTE
♦True Fail-Safe Receiver Operation
♦Available in Small 28-Pin SSOP Package
♦10µs Receiver Input Deglitching (MAX3171 only)
♦All Transmitter Outputs Fault Protected to ±15V,
Tolerate Cable Miswiring
________________________Applications
Data Networking PCI Cards
CSU and DSU Telecommunications
Data Routers
MAX3171/MAX3173
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceivers
________________________________________________________________ Maxim Integrated Products 1
19-1703; Rev 1; 8/01
Ordering Information
PART TEMP. RANGE PIN-PACKAGE
MAX3171CAI 0°C to +70°C 28 SSOP
MAX3173CAI 0°C to +70°C 28 SSOP
D1D2
D3
R1
R2R3
MAX3170
RXD RXC TXDTXC SCTE
D1
R4
D4
D2
D3
R1
R2R3
MAX3171
MAX3173 MAX3172
MAX3174
CTS DSR RTSDTR LLDCD
CTS B
CTS A
DSR B
DSR A
DCD B
DCD A
DTR B
DTR A
RTS B
RTS A
SHIELD
SG
LL A
RXD A
RXD B
RXC B
RXC A
TXC B
TXC A
SCTE B
SCTE A
TXD B
TXD A
DB-25 CONNECTOR
13 5 10 8 22 6 23 20 19 4 1 7 1618 3 9 17 12 15 11 24 14 2
Typical Operating Circuit
Pin Configuration appears at end of data sheet
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
MAX3171/MAX3173
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceivers
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VCC = 3.3V ±5%; C1 = C2 = 1µF, C3 = C4 = C5 = 3.3µF, and TA= TMIN to TMAX, unless otherwise noted. Typical values are at VCC
= +3.3V, TA= +25°C.) (Note 2)
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.
Note 1: V+ and V- can have maximum magnitudes of 7V, but their absolute difference cannot exceed 13V.
(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, T_IN ...............................-0.3V to +6V
Logic Output Voltages
R_OUT...................................................-0.3V to (VCC + 0.3V)
Short-Circuit Duration............................................Continuous
Transmitter Outputs
T_OUT_...............................................................-15V to +15V
Short-Circuit Duration ........................................................60s
Receiver Inputs
R_IN_ ..................................................................-15V to +15V
Continuous Power Dissipation (TA= +70°C)
28-Pin SSOP (derate 11.1mW/°C above +70°C) ........889mW
Operating Temperature Range
MAX3171CAI/MAX3173CAI...............................0°C to +70°C
Storage Temperature Range ............................-65°C to +150°C
Lead Temperature (soldering, 10s) ................................+300°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
DC CHARACTERISTICS
V.11/V.10 modes 220 300
V.11/V.10 modes (no load) 6 23
V.28 mode 24 40
V.28 mode (no load) 6 23
Supply Current
(DCE Mode, Digital Inputs =
GND or VCC, Transmitter
Outputs Static)
ICC
No-cable mode 2 8
mA
V.11/V.10 modes (no load) 20
V.11/V.10 modes (full load) 450
V.28 mode (full load) 40
Internal Power Dissipation PD
No-cable mode 6.6
mW
V.11/V.10 modes (no load) 4.4
V.11/V.10 modes (full load) 4.2
V.28 mode 5.55
V+ Output Voltage V+
No-cable mode 4.6
V
V.11/V.10 modes (no load) -4.0
V.11/V.10 modes (full load) -3.8
V.28 mode -5.45
V- Output Voltage V-
No-cable mode -4.2
V
Charge-Pump Enable Time Delay until V+ and V- specifications met 1 ms
LOGIC INPUTS (M0, M1, M2, DCE/DTE, T_IN)
Input High Voltage VIH 2.0 V
Input Low Voltage VIL 0.8 V
T_IN ±1
M0, M1, M2, DCE / DTE = VCC ±1Logic Input Current IIH, IIL
M0, M1, M2, DCE / DTE = GND 30 50 100
µA
MAX3171/MAX3173
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceivers
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VCC = 3.3V ±5%; C1 = C2 = 1µF, C3 = C4 = C5 = 3.3µF, and TA= TMIN to TMAX, unless otherwise noted. Typical values are at VCC
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
LOGIC OUTPUTS (R_OUT)
Output High Voltage VOH ISOURCE = 1.0mA VCC - 1.0 V
Output Low Voltage VOL ISINK = 1.6mA 0.4 V
Rise or Fall Time tr, tf10% to 90%, Figure 4 15 ns
R_OUT = GND 30 50 100
Output Leakage Current
(Receiver Output Three-Stated) R_OUT = VCC ±1µA
TRANSMITTER OUTPUTS
Output Leakage Current IZ-0.25V ≤ VOUT ≤ +0.25V, power off or
no-cable mode -100 100 µA
V.28 240
V.10 115 kbps
Data Rate
V.11 10 Mbps
Minimum pulse width passed 5
Receiver Glitch Rejection
(MAX3171 only) Minimum pulse width rejected 15 µs
-10V ≤ VAB ≤ +10V, VA or VB grounded,
V.11/V.35, no-cable mode 20 40
Receiver Input Resistance RIN
-15V ≤ VA ≤ +15V, V.28 mode 3 5 7
KΩ
V.10/V.28 64
MAX3171 V.11 64
V.10/V.28 240
kbps
Data Rate
MAX3173 V.11 10 Mbps
V.11 TRANSMITTER
Unloaded Differential Output
Voltage VODO R = 1.95kΩ, Figure 1 4.0 6.0 V
Loaded Differential Output
Voltage VODL R = 50Ω, Figure 1 0.5 ✕ VODO V
Change in Magnitude of Output
Differential Voltage ∆VOD R = 50Ω, Figure 1 0.2 V
Common-Mode Output Voltage VOC R = 50Ω, Figure 1 3.0 V
Change in Magnitude of Output
Common-Mode Voltage ∆VOC R = 50Ω, Figure 1 0.2 V
Short-Circuit Current ISC T_OUTA/B = GND 60 150 mA
Rise or Fall Time tr, tf10% to 90%, Figure 2 10 25 ns
Transmitter Input to Output tPHL, tPLH Figure 2 50 80 ns
Data Skew | tPHL - tPLH | Figure 2 2 10 ns
Output-to-Output Skew tSKEW Figure 2 2 ns
Channel-to-Channel Skew 2ns
V.11 RECEIVER
Differential Threshold Voltage VTH -7V ≤ VCM ≤ +7V -200 -100 -25 mV
Input Hysteresis ∆VTH -7V ≤ VCM ≤ +7V 5 15 mV
MAX3171/MAX3173
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceivers
4 _______________________________________________________________________________________
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX3171 5 10 15 µs
Receiver Input to Output tPHL, tPLH MAX3173 60 120 ns
MAX3171 0.5 4 µs
Data Skew | tP H L - tP LH | MAX3173 5 16 ns
V.10 TRANSMITTER
Unloaded Output Voltage VODO RL = 3.9kΩ, Figure 3 ±4.0 ±4.4 ±6.0 V
Loaded Output Voltage Swing VODL RL = 450Ω, Figure 3 0.9 ✕
VODO V
Short-Circuit Current ISC T_OUTA = GND ±100 ±150 mA
Transmitter Rise or Fall Time tr, tfRL = 450Ω, CL = 100pF, Figure 3 2 µs
Transmitter Input to Output tPHL, tPLH RL = 450Ω, CL = 100pF, Figure 3 2 µs
Data Skew | tP H L - tP LH | RL = 450Ω, CL =100pF, Figure 3 50 ns
V.10 RECEIVER
Threshold Voltage VTH +25 +100 +300 mV
Input Hysteresis ∆VTH 15 mV
MAX3171, Figure 4 5 10 15 µs
Receiver Input to Output tPHL, tPLH MAX3173, Figure 4 60 120 ns
MAX3171, Figure 4 0.5 4 µs
Data Skew | tP H L - tP LH | MAX3173, Figure 4 5 16 ns
V.28 TRANSMITTER
All transmitters loaded with RL = 3kΩ±5.0 ±5.4
Output Voltage Swing VONo load ±6.5 V
Short-Circuit Current ISC T_OUTA = GND ±25 ±60 mA
RL = 3kΩ, CL = 2500pF, measured from +3V
to -3V or from -3V to +3V, Figure 3 430
Output Slew Rate SR
RL = 7kΩ, CL = 150pF, measured from +3V
to -3V or from -3V to +3V, Figure 3 630
V/µs
Transmitter Input to Output tPHL, tPLH Figure 3 1 µs
Data Skew | tP H L - tP LH | Figure 3 100 ns
V.28 RECEIVER
Input Threshold Low VIL 0.8 V
Input Threshold High VIH 2.0 V
Input Hysteresis VHYS 0.5 V
MAX3171, Figure 4 5 10 15
Propagation Delay tPLH, tPHL MAX3173, Figure 4 200 µs
MAX3171, Figure 4 0.5 4.0 µs
Data Skew | tP H L - tP LH | MAX3173, Figure 4 100 ns
ELECTRICAL CHARACTERISTICS (continued)
(VCC = 3.3V ±5%; C1 = C2 = 1µF, C3 = C4 = C5 = 3.3µF, and TA= TMIN to TMAX, unless otherwise noted. Typical values are at VCC
= +3.3V, TA= +25°C.) (Note 2)
Note 2: V+ and V- are also used to supply the MAX3172/MAX3174. The MAX3171/MAX3173 are tested with additional current load
on V+ and V- to capture the effect of loading from the MAX3172/MAX3174 in all operation modes.
MAX3171/MAX3173
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceivers
_______________________________________________________________________________________ 5
0
50
150
100
200
250
V.10/V.11 MODE SUPPLY CURRENT vs.
DATA RATE
MAX3171 toc01
DATA RATE (kbps)
SUPPLY CURRENT (mA)
0.001 0.01 10k 100k0.1 1k 1000k
NO LOAD
FULL LOAD
0
10
40
30
20
60
50
80
70
V.28 MODE SUPPLY CURRENT
vs. DATA RATE
MAX3171 toc02
DATA RATE (kbps)
SUPPLY CURRENT (mA)
0.001 0.01 10k 100k0.1 1k 1000k
FULL LOAD
NO LOAD
-4
-3
-2
-1
0
1
2
3
4
-40 -15 10 35 60 85
V.11 LOADED DIFFERENTIAL
OUTPUT VOLTAGE vs. TEMPERATURE
MAX3171 toc03
TEMPERATURE (°C)
OUTPUT VOLTAGE (V)
VOUT+
VOUT-
RL = 100Ω
Typical Operating Characteristics
(VCC = +3.3V, C1 = C2 = 1.0µF, C3 = C4 = C5 = 3.3µF, TA= +25°C, unless otherwise noted.)
-8
-6
-4
-2
0
2
4
6
8
-40 -15 10 35 60 85
V.28 LOADED OUTPUT VOLTAGE
vs. TEMPERATURE
MAX3171 toc04
TEMPERATURE (°C)
OUTPUT VOLTAGE (V)
VOUT+
VOUT-
RL = 3kΩ
-5
-2
-3
-4
-1
0
1
2
3
4
5
-40 10-15 356085
V.10 LOADED OUTPUT VOLTAGE
vs. TEMPERATURE
MAX3171 toc05
TEMPERATURE (°C)
OUTPUT VOLTAGE (V)
VOUT+
VOUT-
RL = 450Ω
-0.3
-0.1
-0.2
0.1
0
0.2
0.3
-10 0-5 5 10
V.10/V.11 RECEIVER INPUT CURRENT
vs. INPUT VOLTAGE
MAX3171 toc06
INPUT VOLTAGE (V)
INPUT CURRENT (mA)
-4
-3
-2
-1
0
1
2
3
4
-15 -5-10 0 5 10 15
V.28 RECEIVER INPUT CURRENT
vs. INPUT VOLTAGE
MAX3171 toc07
INPUT VOLTAGE (V)
INPUT CURRENT (mA)
0
4
2
10
8
6
16
14
12
18
0 1000500 1500 2000 2500 3000
V.28 SLEW RATE
vs. LOAD CAPACITANCE
MAX3171toc11
CAPACITANCE (pF)
SLEW RATE (V/µs)
+SLEW
-SLEW
0
0.5
1.5
1.0
2.0
2.5
0 1000500 1500 2000 2500 3000
V.10 TRANSMITTER RISE AND FALL TIMES
vs. LOAD CAPACITANCE
MAX3171toc12
CAPACITANCE (pF)
RISE/FALL TIME (µs)
FALL
RISE
MAX3171/MAX3173
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceivers
6 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(VCC = +3.3V, C1 = C2 = 1.0µF, C3 = C4 = C5 = 3.3µF, TA= +25°C, unless otherwise noted.)
TIN2
TOUT2/
RIN2
ROUT2
5V/div
10µs/div
MAX3173 LOOPBACK SCOPE PHOTO
530A MODE (UNLOADED)
MAX3171 toc10
TIN
TOUT/
RIN
ROUT
5V/div
10µs/div
MAX3173 LOOPBACK SCOPE PHOTO
V.11 MODE (UNLOADED)
MAX3171 toc08
TIN
TOUT/
RIN
ROUT
5V/div
10µs/div
MAX3171 LOOPBACK SCOPE PHOTO
V.28 MODE (RL = 3kΩ)
MAX3171 toc09
Figure 1. V.11 DC Test Circuit Figure 2. V.11 AC Test Circuit
100pF
50pF
100pF
100ΩRxTx
Test Circuits
VOC
R
R
VOD
MAX3171/MAX3173
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceiver
_______________________________________________________________________________________ 7
Pin Description
PIN NAME FUNCTION
1V+
Positive Supply Generated by the Charge Pump (connect to V+ pin of MAX3172/MAX3174).
Bypass V+ to ground with a 3.3µF ceramic capacitor.
2 C2+ Positive Terminal of the Inverting Charge-Pump Capacitor. Connect C2+ to C2- with a 1µF
ceramic capacitor.
3C2-
Negative Terminal of the Inverting Charge-Pump Capacitor. Connect C2+ to C2- with a 1µF
ceramic capacitor.
4V-
Negative Supply Generated by the Charge Pump (connect to V- pin of MAX3172/MAX3174).
Bypass V- to ground with a 3.3µF ceramic capacitor.
5, 6, 7 T_IN Transmitter CMOS Inputs (T1IN, T2IN, T3IN)
8, 9, 10 R_OUT Receiver CMOS Outputs (R1OUT, R2OUT, R3OUT)
11, 12, 13 M_ Mode Select Inputs (M0, M1, M2). Internally pulled up to VCC. See Table 1 for detailed
information.
14 DCE/DTE DCE/DTE Mode Select Input. Logic level high selects DCE interface; logic level low selects
DTE interface. Internally pulled up to VCC.
15, 18 R_INB Noninverting Receiver Inputs (R3INB, R2INB)
16, 17 R_INA Inverting Receiver Inputs (R3INA, R2INA)
19 T3OUTB/R1INB Noninverting Transmitter Output/Noninverting Receiver Input
20 T3OUTA/R1INA Inverting Transmitter Output/Inverting Receiver Input
21, 23 T_OUTB Noninverting Transmitter Outputs (T2OUTB, T1OUTB)
22, 24 T_OUTA Inverting Transmitter Outputs (T2OUTA, T1OUTA)
25 C1- Negative Terminal of the Voltage-Doubler Charge-Pump Capacitor. Connect C1+ to C1- with
a 1µF ceramic capacitor.
26 GND Ground
27 VCC +3.3V Supply Voltage (±5%). Bypass VCC to ground with a 3.3µF ceramic capacitor.
28 C1+ Positive Terminal of the Voltage-Doubler Charge-Pump Capacitor. Connect C1+ to C1- with a
1µF ceramic capacitor.
Figure 3. V.10/V.28 Driver Test Circuit
RL
CL
Tx
Figure 4. V.10/V.28 Receiver Test Circuit
Test Circuits (continued)
50pF
Tx Rx
MAX3171/MAX3173
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceivers
8 _______________________________________________________________________________________
Detailed Description
The MAX3171/MAX3173 are three-driver/three-receiver
multiprotocol transceivers that operate from a single
+3.3V supply. The MAX3171/MAX3173, along with the
MAX3170 and MAX3172/MAX3174, form a complete
software-selectable DTE or DCE interface port that sup-
ports the V.28 (RS-232), V.10/V.11 (RS-449, V.36, EIA-
530, EIA-530-A, X.21, RS-423), and V.35 protocols. The
MAX3171/MAX3173 carry the control signals, while the
MAX3170 transceiver carries the high-speed clock and
data signals. The MAX3172/MAX3174 provide termina-
tion for the clock and data signals and have an extra
transceiver for applications requiring four transceivers
for control handshaking.
The MAX3171/MAX3173 feature a 2mA no-cable mode,
true fail-safe operation, and thermal shutdown circuitry.
Thermal shutdown protects the drivers against exces-
sive power dissipation. When activated, the thermal
shutdown circuitry places the driver outputs into a high-
impedance state.
Mode Selection
The state of mode select pins M0, M1, and M2 determines
which serial interface protocol is selected (Table 1). The
state of the DCE/DTE input determines whether the trans-
ceivers will be configured as a DTE serial port or a DCE
serial port. When the DCE/DTE input is logic HIGH, dri-
ver T3 is activated and receiver R1 is disabled. When
the DCE/DTE input is logic LOW, driver T3 is disabled
and receiver R1 is activated. M0, M1, M2, and
DCE/DTE are internally pulled up to VCC to ensure logic
HIGH if left unconnected.
The MAX3171/MAX3173’s mode can be selected
through software control of the M0, M1, M2, and
DCE/DTE inputs. Alternatively, the mode can be select-
ed by shorting the appropriate combination of mode
control inputs to GND (the inputs left floating will be
internally pulled up to VCC). If the M0, M1, and M2
mode inputs are all unconnected, the MAX3171/
MAX3173 will enter no-cable mode.
Table 1. Mode Selection
LOGIC INPUTS TRANSMITTERS RECEIVERS
PROTOCOL M2 M1 M0 DCE/DTE T1 T2 T3 R1 R2 R3
V.11 0 0 0 0 V.11 V.11 Z V.11 V.11 V.11
RS-530A 0 0 1 0 V.11 V.10 Z V.11 V.10 V.11
RS-530 0 1 0 0 V.11 V.11 Z V.11 V.11 V.11
X.21 0 1 1 0 V.11 V.11 Z V.11 V.11 V.11
V.35 1 0 0 0 V.28 V.28 Z V.28 V.28 V.28
RS-449/V.36 1 0 1 0 V.11 V.11 Z V.11 V.11 V.11
V.28/RS-232 1 1 0 0 V.28 V.28 Z V.28 V.28 V.28
No cable 1 1 1 0 ZZZZZZ
V.11 0 0 0 1 V.11 V.11 V.11 Z V.11 V.11
RS-530A 0 0 1 1 V.11 V.10 V.11 Z V.10 V.11
RS-530 0 1 0 1 V.11 V.11 V.11 Z V.11 V.11
X.21 0 1 1 1 V.11 V.11 V.11 Z V.11 V.11
V.35 1 0 0 1 V.28 V.28 V.28 Z V.28 V.28
RS-449/V.36 1 0 1 1 V.11 V.11 V.11 Z V.11 V.11
V.28/RS-232 1 1 0 1 V.28 V.28 V.28 Z V.28 V.28
No cable 1 1 1 1 ZZZZZZ
1
2
28
27
VCC
GND
C1+
3
4
26
25
MAX3171
MAX3173
C1-
C2-
V-
V+
C2+
C2
1µF
C5
3.3µF
C1
1µF
C3
3.3µF
C4
3.3µF
Figure 5. Charge-Pump Connections
Z = High impedance
MAX3171/MAX3173
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceiver
_______________________________________________________________________________________ 9
No-Cable Mode
The MAX3171/MAX3173 enter no-cable mode when the
mode select pins are left unconnected or tied HIGH
(M0 = M1 = M2 = 1). In this mode, the multiprotocol dri-
vers and receivers are disabled and the supply current
is less than 8mA. The receiver outputs enter a high-
impedance state in no-cable mode, which allows these
output lines to be shared with other receivers (the
receiver outputs have an internal pullup resistor to pull
the outputs HIGH if not driven). Also, in no-cable mode,
the transmitter outputs enter a high-impedance state,
so these output lines can be shared with other devices.
Dual Charge-Pump Voltage Converter
The MAX3171/MAX3173 internal power supply consists
of a regulated dual charge pump that provides positive
and negative output voltages from a +3.3V supply. The
charge pump operates in discontinuous mode: If the out-
put voltage is less than the regulated voltage, the charge
pump is enabled; if the output voltage exceeds the regu-
lated voltage, the charge pump is disabled. Each charge
pump requires a flying capacitor (C1, C2) and a reser-
voir capacitor (C3, C4) to generate the V+ and V- sup-
plies. See Figure 5 for charge-pump connections.
The charge pump is designed to supply V+ and V-
power to the MAX3172/MAX3174 in addition to the
MAX3171/MAX3173 internal transceivers. Connect the
MAX3172/MAX3174 V+ and V- terminals to the
MAX3171/MAX3173 V+ and V- terminals, respectively.
Fail-Safe
The MAX3171/MAX3173 guarantee a logic HIGH
receiver output when the receiver inputs are shorted or
open, or when they are connected to a terminated
transmission line with drivers disabled. The V.11 receiv-
er threshold is set between -25mV and -200mV to guar-
antee fail-safe operation. If the differential receiver input
voltage (B - A) is ≥-25mV, R_OUT is logic HIGH. In the
case of a terminated bus with all transmitters disabled,
the receiver’s differential input voltage is pulled to 0 by
the termination. With the MAX3171/MAX3173 receiver
thresholds, this results in R_OUT logic HIGH with a
25mV (min) noise margin.
The V.10 receiver threshold is set between +25mV and
+300mV. If the V.10 receiver input voltage is ≤+25mV,
ROUT is logic HIGH. The V.28 receiver threshold is set
between 0.8V and 2.0V. If the receiver input voltage is
≤0.8V, ROUT is logic HIGH. In the case of a terminated
bus with transmitters disabled, the V.10/V.28 receiver’s
input voltage is pulled to ground by the termination.
With the MAX3172/MAX3174 receiver thresholds, this
results in R_OUT logic HIGH.
Applications Information
Capacitor Selection
The capacitors used for the charge pumps, as well as
the supply bypassing, should have a low-ESR and low-
temperature coefficient. Multilayer ceramic capacitors
with an X7R dielectric offer the best combination of per-
formance, size, and cost. The flying capacitors (C1,
C2) should have a value of 1µF, while the reservoir
capacitors (C3, C4) and bypass capacitor (C5) should
have a minimum value of 3.3µF (Figure 5). To reduce
the ripple present on the transmitter outputs, capacitors
C3, C4, and C5 can be increased. Do not increase the
value of C1 and C2.
Local Loopback Control Signal
For applications that require the use of local loopback
(LL) signal routing, an extra transceiver is available for
use on the MAX3172/MAX3174 multiprotocol termina-
tion network device.
Cable-Selectable Mode
Figure 6 shows a cable-selectable mulitprotocol inter-
face. The mode control lines (M0, M1, M2, and
DCE/DTE) are wired to the DB-25 connector. To select
the serial interface mode, the appropriate combinations
of M0, M1, M2, and DCE/DTE are grounded within the
cable wiring. The control lines that are not grounded
are pulled high by the internal pullups on the MAX3170.
The serial interface protocol of the MAX3171/MAX3173
(MAX3170 and MAX3172/MAX3174) is now selected
based on the cable connected to the DB-25 interface.
V.11 (RS-422) Interface
As shown in Figure 7, the V.11 protocol is a fully bal-
anced differential interface. The V.11 driver generates
±2V (min) between nodes A and B when 100Ω(min)
resistance is presented at the load. The V.11 receiver is
sensitive to ±200mV differential signals at the receiver
inputs A’ and B’. The V.11 receiver input must comply
with the impedance curve of Figure 8 and reject com-
mon-mode signals up to ±7V developed across the
cable (referenced from C to C’ in Figure 7).
The MAX3171/MAX3173 V.11 mode receiver has a dif-
ferential threshold between -200mV and -25mV to
ensure that the receiver has proper fail-safe operation
(see Fail-Safe). To aid in rejecting system noise, the
MAX3171/MAX3173 V.11 receiver has a 15mV (typ)
hysteresis. Switch S3 in Figure 9 is open in V.11 mode
to disable the V.28 5kΩtermination at the inverting
receiver input. Because the control signals are slow
(64kbps), 100Ωtermination resistance is generally not
required for the MAX3171/MAX3173.
MAX3171/MAX3173
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceivers
10 ______________________________________________________________________________________
V.10 Interface
The V.10 interface (Figure 10) is an unbalanced single-
ended interface capable of driving a 450Ωload. The
V.10 driver generates a ±4V (min) VODO voltage across
A' and C' when unloaded and a minimum of ±0.9 ✕
VODO voltage with a 450Ωload. The V.10 receiver input
trip threshold is defined between +300mV and -300mV
with the input impedance characteristic shown in
Figure 8.
The MAX3171/MAX3173 V.10 mode receiver has a
threshold between +25mV and +300mV to ensure that
the receiver has proper fail-safe operation (see Fail-
D1D2
D3
R1
R2R3
MAX3170
RXD(DTE)
TXD(DCE)
RXC(DTE)
SCTE(DCE)
TXD(DTE)
RXD(DCE)
TXC(DTE)
TXC(DCE)
SCTE(DTE)
RXC(DCE)
M1
M2
M0
DCE/DTE
D1 R4
D4
D2
D3
R1
R2R3
MAX3171
MAX3173
M1
M2
M0
DCE/DTE
CTS(DTE)
RTS(DCE)
DSR(DTE)
DTR(DCE)
RTS(DTE)
CTS(DCE)
DTR(DTE)
DSR(DCE)
DCD(DTE)
DCD(DCE)
M2M1M0
M1M0
DCE/DTE
DCE/DTE
CTS B
CTS A
DSR
DSR
DCD
DCD
DTR B
DTR A
RTS B
RTS A
SHIELD
SG
RXD
RXD
RXC
RXC
TXC B
TXC A
SCTE B
SCTE A
TXD B
TXD A
DB-25 CONNECTOR
DTE
DCE
RTS B
RTS A
DTR B
DTR A
DCD
DCD
DSR
DSR
CTS B
CTS A
TXD B
TXD A
SCTE B
SCTE A
TXC B
TXC A
RXC
RXC
RXD
RXD
CABLE WIRING FOR
MODE SELECTION
MODE
V.35
RS-449, V.36
RS-232
PIN 18
PIN 7
N.C.
PIN 7
PIN 21
PIN 7
PIN 7
N.C.
CABLE WIRING FOR
DCE/DTE SELECTION
MODE
DTE
DCE
PIN 25
PIN 7
N.C.
13 5 10 8 22 6 23 20 19 4 1 7 18 21 25 16 3 9 17 12 15 11 24 14 2
VCC
MAX3172
MAX3174
Figure 6. Cable-Selectable Multiprotocol DCE/DTE Port
Figure 7. Typical V.11 Interface
100Ω
MIN
A′
B′
C′
A
B
C
GENERATOR
BALANCED
INTERCONNECTING
CABLE
CABLE
TERMINATION RECEIVER
LOAD
MAX3171/MAX3173
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceiver
______________________________________________________________________________________ 11
R6
10kΩ
R8
5kΩ
A′
B′
C′
A
B
GND
R5
30kΩ
R7
10kΩ
R4
30kΩ
S4
S5
MAX3171
MAX3173
S3
RECEIVER
Figure 12. V.28 Termination and Internal Resistance Networks
Figure 11. V.10 Internal Resistance Network
R6
10kΩ
R8
5kΩ
A′
B′
C′
A
B
GND
R5
30kΩ
R7
10kΩ
R4
30kΩ
MAX3171
MAX3173
S3
RECEIVER
Figure 10. Typical V.10/V.28 Interface
Figure 9. V.11 Termination and Internal Resistance Networks
R6
10kΩ
R8
5kΩ
A′
B′
C′
A
B
GND
R5
30kΩ
R7
10kΩ
R4
30kΩ
MAX3171
MAX3173
S3
RECEIVER
Figure 8. Receiver Input Impedance Curve
-3.25mA
3.25mA
-10V
+10V
-3V
+3V
VZ
IZ
A′
C′
A
C
GENERATOR
UNBALANCED
INTERCONNECTING
CABLE
CABLE
TERMINATION RECEIVER
LOAD
MAX3171/MAX3173
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceivers
12 ______________________________________________________________________________________
Safe). To aid in rejecting system noise, the
MAX3171/MAX3173 V.10 receiver has 15mV (typ) hys-
teresis. Switch S3 in Figure 11 is open in V.10 mode to
disable the 5kΩV.28 termination at the receiver input.
Switch S4 is closed, and switch S5 is open to internally
ground the receiver B input.
V.28 Interface
The V.28 interface is an unbalanced single-ended inter-
face (Figure 12). The V.28 generator provides ±5V
(min) across the load impedance between A’ and C’.
The V.28 standard specifies input trip points at ±3V.
The MAX3171/MAX3173 V.28 mode receiver has a
threshold between +0.8V and +2.0V to ensure that the
receiver has proper fail-safe operation (see Fail-Safe). To
aid in rejecting system noise, the MAX3171/MAX3173
V.28 receiver has a 500mV (typ) hysteresis. Switch S3 in
Figure 12 is closed in V.28 mode to enable the 5kΩV.28
termination at the receiver input.
Receiver Glitch Rejection
To facilitate operation in an unterminated or otherwise
noisy system, the MAX3171 features 10µs of receiver
input glitch rejection in V.10, V.11, and V.28 modes.
The glitch rejection circuitry blocks the reception of
high-frequency noise (tB< 5µs) while receiving a low-
frequency signal (tB> 15µs), allowing glitch-free opera-
tion in unterminated systems at up to 64kbps. The
MAX3173 does not have this feature and can be oper-
ated at data rates up to 240kbps if properly terminated.
DTE vs. DCE Operation
Figure 13 shows a DCE or DTE controller-selectable
interface. The DCE/DTE input switches the port’s mode
of operation. A logic high selects DCE, which enables
Figure 13. Multiprotocol DCE/
DTE
Port
D1D2
D3
R1
R2R3
MAX3170
RXD(DTE)
TXD(DCE)
RXC(DTE)
SCTE(DCE)
LL(DTE)
LL(DCE)
TXD(DTE)
RXD(DCE)
TXC(DTE)
TXC(DCE)
SCTE(DTE)
RXC(DCE)
M1
M2
M0
DCE/DTE
M1
M2
M0
DCE/DTE
D1 R4
D4
D2
D3
R1
R2R3
MAX3171
MAX3173
M1
M2
M0
DCE/DTE
CTS(DTE)
RTS(DCE)
DSR(DTE)
DTR(DCE)
RTS(DTE)
CTS(DCE)
DTR(DTE)
DSR(DCE)
DCD(DTE)
DCD(DCE)
M2M1M0 DCE/DTE
CTS B
CTS A
DSR B
DSR A
DCD B
DCD A
DTR B
DTR A
RTS B
RTS A
SHIELD
SG
LL A
RXD B
RXD A
RXC B
RXC A
TXC B
TXC A
SCTE B
SCTE A
TXD B
TXD A
DB-25 CONNECTOR
DTE
DCE
RTS B
RTS A
DTR B
DTR A
DCD B
DCD A
DSR B
DSR A
CTS B
CTS A
LL A
TXD B
TXD A
SCTE B
SCTE A
TXC B
TXC A
RXC B
RXC A
RXD B
RXD A
13 5 10 8 22 6 23 20 19 4 1 7 18 16 3 9 17 12 15 11 24 14 2
MAX3172
MAX3174
driver 3 on the MAX3171/MAX3173, driver 3 on the
MAX3170, and driver 4 on the MAX3172/MAX3174. A
logic low selects DTE, which enables receiver 1 on the
MAX3171/MAX3173, receiver 1 on the MAX3170, and
receiver 4 on the MAX3172/MAX3174.
This application requires only one DB-25 connector. See
Figure 13 for complete signal routing in DCE and DTE
modes. For example, driver 3 routes the DCD (DCE) sig-
nal to pins 22 and 6 in DCE mode, while in DTE mode,
receiver 1 routes pins 22 and 6 to DCD (DTE).
Complete Multiprotocol X.21 Interface
Figure 14 shows a complete DCE-to-DTE interface
operating in X.21 mode. The MAX3171/MAX3173 gen-
erate the control signals, and the MAX3170 is used to
generate the clock and data signals. The MAX3172/
MAX3174 generate local loopback and are used to ter-
minate the clock and data signals to support the V.11
protocol for cable termination. The control signals do
not need external termination.
MAX3171/MAX3173
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceiver
______________________________________________________________________________________ 13
D1
D2
D3
R3
R2
R1
D3
D2
D1
D4
TXD
SCTE
TXC
RXC
RXD
LL
D4
R4
R4
R1
R2
R3 103Ω
103Ω
103Ω
103Ω
103Ω
MAX3170MAX3172
MAX3174
MAX3172
MAX3174
MAX3170
D1
D2
D3
R3
R2
R1
D3
D2
D1
RTS
DTR
DCD
DSR
CTS
R1
R2
R3
MAX3171
MAX3173
MAX3171
MAX3173
SERIAL
CONTROLLER
TXD
SCTE
TXC
RXC
RXD
RTS
DTR
DCD
DSR
CTS
LL
SERIAL
CONTROLLER
TXD
SCTE
TXC
RXC
RXD
RTS
DTR
DCD
DSR
CTS
LL
DCE
DTE
Figure 14. DCE-to-DTE X.21 Interface
Compliance Testing
A European Standard EN 45001 test report is available
for the MAX3170–MAX3174 chipset. A copy of the test
report will be available from Maxim.
Pin Configuration
28
27
26
25
24
23
22
21
20
19
18
17
16
15
1
2
3
4
5
6
7
8
9
10
11
12
13
14
C1+
VCC
GND
C1-
T1OUTA
T1OUTB
R3INB
T2OUTA
T2OUTB
T3OUTA/R1INA
T3OUTB/R1INB
R2INB
R2INA
R3INA
DCE/DTE
M2
M1
M0
R3OUT
R2OUT
R1OUT
T3IN
T2IN
T1IN
V-
C2-
C2+
V+
SSOP
TOP VIEW
MAX3171
MAX3173
Chip Information
TRANSISTOR COUNT: 1763
PROCESS: BiCMOS
MAX3171/MAX3173
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceivers
14 ______________________________________________________________________________________
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 ____________________ 15
© 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
Package Information
SSOP.EPS
MAX3171/MAX3173
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceiver
