MAXIM MAX3173

19-1703; Rev 1; 8/01
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceivers
Features
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 interface 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 nocable mode is entered when all mode pins (M0, M1,
and M2) are pulled high or left unconnected. In nocable mode, supply current decreases to 2mA and all
transmitter and receiver outputs are disabled (high
impedance). Short-circuit limiting and thermal-shutdown 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 available 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.
♦ 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
MAX3171
MAX3173
CTS
DSR
R3
R2
R1
DCD
DTR
RTS
D3
D2
D1
♦
♦
♦
♦
♦
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
Ordering Information
PART
TEMP. RANGE
PIN-PACKAGE
MAX3171CAI
0°C to +70°C
28 SSOP
MAX3173CAI
0°C to +70°C
28 SSOP
Routers appears at end of data sheet
PinData
Configuration
Typical Operating Circuit
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
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.
1
MAX3171/MAX3173
General Description
MAX3171/MAX3173
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control 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, 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
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%; 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)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DC CHARACTERISTICS
V.11/V.10 modes
Supply Current
(DCE Mode, Digital Inputs =
GND or VCC, Transmitter
Outputs Static)
Internal Power Dissipation
ICC
PD
220
300
V.11/V.10 modes (no load)
6
23
V.28 mode
24
40
V.28 mode (no load)
6
23
No-cable mode
2
8
V.11/V.10 modes (no load)
20
V.11/V.10 modes (full load)
450
V.28 mode (full load)
40
No-cable mode
V.11/V.10 modes (no load)
V+ Output Voltage
V+
V-
6.6
V.11/V.10 modes (full load)
4.2
V.28 mode
5.55
V
4.6
V.11/V.10 modes (no load)
-4.0
V.11/V.10 modes (full load)
-3.8
V.28 mode
-5.45
No-cable mode
Charge-Pump Enable Time
mW
4.4
No-cable mode
V- Output Voltage
mA
V
-4.2
Delay until V+ and V- specifications met
1
ms
LOGIC INPUTS (M0, M1, M2, DCE/DTE, T_IN)
Input High Voltage
VIH
Input Low Voltage
VIL
2.0
V
0.8
Logic Input Current
IIH, IIL
2
±1
M0, M1, M2, DCE / DTE = VCC
M0, M1, M2, DCE / DTE = GND
V
±1
T_IN
30
50
_______________________________________________________________________________________
100
µA
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceivers
(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
0.4
V
LOGIC OUTPUTS (R_OUT)
Output High Voltage
VOH
ISOURCE = 1.0mA
Output Low Voltage
VOL
ISINK = 1.6mA
Rise or Fall Time
tr, tf
10% to 90%, Figure 4
R_OUT = GND
Output Leakage Current
(Receiver Output Three-Stated)
VCC - 1.0
V
15
30
50
ns
100
±1
R_OUT = VCC
µA
TRANSMITTER OUTPUTS
Output Leakage Current
IZ
-0.25V ≤ VOUT ≤ +0.25V, power off or
no-cable mode
-100
100
V.28
240
Data Rate
V.10
115
Receiver Glitch Rejection
(MAX3171 only)
Minimum pulse width passed
V.11
Receiver Input Resistance
RIN
10
20
40
-15V ≤ VA ≤ +15V, V.28 mode
3
5
Data Rate
MAX3173
Mbps
15
-10V ≤ VAB ≤ +10V, VA or VB grounded,
V.11/V.35, no-cable mode
MAX3171
kbps
5
Minimum pulse width rejected
V.10/V.28
64
V.11
64
V.10/V.28
240
V.11
10
µA
µs
KΩ
7
kbps
Mbps
V.11 TRANSMITTER
Unloaded Differential Output
Voltage
VODO
R = 1.95kΩ, Figure 1
Loaded Differential Output
Voltage
VODL
R = 50Ω, Figure 1
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, tf
10% to 90%, Figure 2
10
25
ns
Figure 2
50
80
ns
| tPHL - tPLH | Figure 2
2
10
Transmitter Input to Output
Data Skew
Output-to-Output Skew
tPHL, tPLH
tSKEW
4.0
6.0
0.5 ✕ VODO
Figure 2
Channel-to-Channel Skew
V
V
ns
2
ns
2
ns
V.11 RECEIVER
Differential Threshold Voltage
Input Hysteresis
VTH
-7V ≤ VCM ≤ +7V
-200
-100
∆VTH
-7V ≤ VCM ≤ +7V
5
15
-25
mV
mV
_______________________________________________________________________________________
3
MAX3171/MAX3173
ELECTRICAL CHARACTERISTICS (continued)
MAX3171/MAX3173
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceivers
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)
PARAMETER
Receiver Input to Output
Data Skew
V.10 TRANSMITTER
Unloaded Output Voltage
Loaded Output Voltage Swing
SYMBOL
tPHL, tPLH
| tPHL - tPLH |
VODO
VODL
CONDITIONS
MIN
TYP
MAX
UNITS
5
10
15
µs
MAX3173
60
120
ns
MAX3171
0.5
4
µs
MAX3173
5
16
ns
±4.4
±6.0
V
MAX3171
RL = 3.9kΩ, Figure 3
±4.0
RL = 450Ω, Figure 3
0.9 ✕
VODO
V
±100
±150
Short-Circuit Current
ISC
T_OUTA = GND
Transmitter Rise or Fall Time
tr, tf
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 Input to Output
Data Skew
mA
V.10 RECEIVER
Threshold Voltage
Input Hysteresis
Receiver Input to Output
Data Skew
VTH
+25
∆VTH
tPHL, tPLH
| tPHL - tPLH |
+100
+300
15
MAX3171, Figure 4
5
mV
mV
10
15
µs
MAX3173, Figure 4
60
120
ns
MAX3171, Figure 4
0.5
4
µs
MAX3173, Figure 4
5
16
ns
V.28 TRANSMITTER
Output Voltage Swing
VO
Short-Circuit Current
ISC
All transmitters loaded with RL = 3kΩ
Data Skew
±6.5
±25
T_OUTA = GND
4
±60
V
mA
30
V/µs
SR
RL = 7kΩ, CL = 150pF, measured from +3V
to -3V or from -3V to +3V, Figure 3
Transmitter Input to Output
±5.4
No load
RL = 3kΩ, CL = 2500pF, measured from +3V
to -3V or from -3V to +3V, Figure 3
Output Slew Rate
±5.0
6
30
tPHL, tPLH
Figure 3
1
µs
| tPHL - tPLH |
Figure 3
100
ns
V.28 RECEIVER
Input Threshold Low
VIL
Input Threshold High
VIH
Input Hysteresis
Propagation Delay
Data Skew
0.8
2.0
VHYS
tPLH, tPHL
| tPHL - tPLH |
V
0.5
MAX3171, Figure 4
5
MAX3173, Figure 4
MAX3171, Figure 4
MAX3173, Figure 4
V
10
V
15
200
0.5
4.0
100
µs
µs
ns
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.
4
_______________________________________________________________________________________
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceivers
70
150
100
60
50
40
30
FULL LOAD
20
50
0.01
0.1
1k
10k
100k
1
0
-1
-2
NO LOAD
0
0.001
1000k
VOUT-
-4
0.01
0.1
1k
10k
100k
1000k
-40
-15
10
35
60
85
DATA RATE (kbps)
TEMPERATURE (°C)
V.28 LOADED OUTPUT VOLTAGE
vs. TEMPERATURE
V.10 LOADED OUTPUT VOLTAGE
vs. TEMPERATURE
V.10/V.11 RECEIVER INPUT CURRENT
vs. INPUT VOLTAGE
VOUT+
2
0
-2
VOUT+
RL = 450Ω
3
OUTPUT VOLTAGE (V)
4
4
VOUT-
2
1
0
-1
-2
-3
-6
0.3
MAX3171 toc06
6
5
0.2
INPUT CURRENT (mA)
RL = 3kΩ
MAX3171 toc05
8
-4
-3
DATA RATE (kbps)
MAX3171 toc04
0
0.001
VOUT-
0.1
0
-0.1
-0.2
-4
-5
-8
-15
10
35
60
-0.3
-40
85
-15
10
35
60
85
-5
0
5
10
TEMPERATURE (°C)
INPUT VOLTAGE (V)
V.28 RECEIVER INPUT CURRENT
vs. INPUT VOLTAGE
V.28 SLEW RATE
vs. LOAD CAPACITANCE
V.10 TRANSMITTER RISE AND FALL TIMES
vs. LOAD CAPACITANCE
3
16
SLEW RATE (V/µs)
0
-1
12
+SLEW
-SLEW
10
8
6
-2
4
-3
2
-10
-5
0
5
INPUT VOLTAGE (V)
10
15
FALL
1.5
RISE
1.0
0.5
0
0
-4
2.0
14
2
1
2.5
MAX3171toc12
18
MAX3171 toc07
4
-15
-10
TEMPERATURE (°C)
RISE/FALL TIME (µs)
-40
MAX3171toc11
OUTPUT VOLTAGE (V)
VOUT+
2
NO LOAD
10
INPUT CURRENT (mA)
RL = 100Ω
3
OUTPUT VOLTAGE (V)
SUPPLY CURRENT (mA)
200
4
MAX3171 toc02
FULL LOAD
SUPPLY CURRENT (mA)
80
MAX3171 toc01
250
V.11 LOADED DIFFERENTIAL
OUTPUT VOLTAGE vs. TEMPERATURE
V.28 MODE SUPPLY CURRENT
vs. DATA RATE
MAX3171 toc03
V.10/V.11 MODE SUPPLY CURRENT vs.
DATA RATE
0
500
1000
1500
2000
CAPACITANCE (pF)
2500
3000
0
500
1000
1500
2000
2500
3000
CAPACITANCE (pF)
_______________________________________________________________________________________
5
MAX3171/MAX3173
Typical Operating Characteristics
(VCC = +3.3V, C1 = C2 = 1.0µF, C3 = C4 = C5 = 3.3µF, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(VCC = +3.3V, C1 = C2 = 1.0µF, C3 = C4 = C5 = 3.3µF, TA = +25°C, unless otherwise noted.)
ROUT
5V/div
5V/div
TIN
ROUT2
TOUT2/
RIN2
TOUT/
RIN
TOUT/
RIN
MAX3171 toc10
MAX3171 toc09
ROUT
MAX3173 LOOPBACK SCOPE PHOTO
530A MODE (UNLOADED)
MAX3171 LOOPBACK SCOPE PHOTO
V.28 MODE (RL = 3kΩ)
MAX3173 LOOPBACK SCOPE PHOTO
V.11 MODE (UNLOADED)
MAX3171 toc08
MAX3171/MAX3173
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceivers
5V/div
TIN2
TIN
10µs/div
10µs/div
10µs/div
Test Circuits
100pF
R
Tx
VOD
Rx
100Ω
50pF
R
VOC
100pF
Figure 1. V.11 DC Test Circuit
6
Figure 2. V.11 AC Test Circuit
_______________________________________________________________________________________
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceiver
Tx
Tx
CL
Rx
RL
Figure 3. V.10/V.28 Driver Test Circuit
50pF
Figure 4. V.10/V.28 Receiver Test Circuit
Pin Description
PIN
NAME
FUNCTION
1
V+
2
C2+
Positive Terminal of the Inverting Charge-Pump Capacitor. Connect C2+ to C2- with a 1µF
ceramic capacitor.
3
C2-
Negative Terminal of the Inverting Charge-Pump Capacitor. Connect C2+ to C2- with a 1µF
ceramic capacitor.
4
V-
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
8, 9, 10
R_OUT
11, 12, 13
M_
14
DCE/DTE
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-
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.
Positive Supply Generated by the Charge Pump (connect to V+ pin of MAX3172/MAX3174).
Bypass V+ to ground with a 3.3µF ceramic capacitor.
Transmitter CMOS Inputs (T1IN, T2IN, T3IN)
Receiver CMOS Outputs (R1OUT, R2OUT, R3OUT)
Mode Select Inputs (M0, M1, M2). Internally pulled up to VCC. See Table 1 for detailed
information.
DCE/DTE Mode Select Input. Logic level high selects DCE interface; logic level low selects
DTE interface. Internally pulled up to VCC.
Negative Terminal of the Voltage-Doubler Charge-Pump Capacitor. Connect C1+ to C1- with
a 1µF ceramic capacitor.
_______________________________________________________________________________________
7
MAX3171/MAX3173
Test Circuits (continued)
MAX3171/MAX3173
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceivers
Table 1. Mode Selection
LOGIC INPUTS
PROTOCOL
TRANSMITTERS
RECEIVERS
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
Z
Z
Z
Z
Z
Z
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
Z
Z
Z
Z
Z
Z
Z = High impedance
1
C3
3.3µF
2
C2
1µF
3
4
MAX3171
28
V+ MAX3173 C1+
C2+
VCC
C2-
GND
V-
C1-
27
26
C5
3.3µF
C1
1µF
Mode Selection
25
C4
3.3µF
Figure 5. Charge-Pump Connections
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 supports the V.28 (RS-232), V.10/V.11 (RS-449, V.36, EIA530, 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 termination for the clock and data signals and have an extra
transceiver for applications requiring four transceivers
for control handshaking.
8
The MAX3171/MAX3173 feature a 2mA no-cable mode,
true fail-safe operation, and thermal shutdown circuitry.
Thermal shutdown protects the drivers against excessive power dissipation. When activated, the thermal
shutdown circuitry places the driver outputs into a highimpedance state.
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 transceivers will be configured as a DTE serial port or a DCE
serial port. When the DCE/DTE input is logic HIGH, driver 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 selected 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.
_______________________________________________________________________________________
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceiver
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 output voltage is less than the regulated voltage, the charge
pump is enabled; if the output voltage exceeds the regulated voltage, the charge pump is disabled. Each charge
pump requires a flying capacitor (C1, C2) and a reservoir capacitor (C3, C4) to generate the V+ and V- supplies. See Figure 5 for charge-pump connections.
The charge pump is designed to supply V+ and Vpower 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 receiver threshold is set between -25mV and -200mV to guarantee 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 lowtemperature coefficient. Multilayer ceramic capacitors
with an X7R dielectric offer the best combination of performance, 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 termination network device.
Cable-Selectable Mode
Figure 6 shows a cable-selectable mulitprotocol interface. 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 balanced 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 common-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 differential 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 5kΩ termination at the inverting
receiver input. Because the control signals are slow
(64kbps), 100Ω termination resistance is generally not
required for the MAX3171/MAX3173.
_______________________________________________________________________________________
9
MAX3171/MAX3173
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 drivers and receivers are disabled and the supply current
is less than 8mA. The receiver outputs enter a highimpedance 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.
MAX3171
MAX3173
R3
R2
RXD(DTE)
TXD(DCE)
RXC(DTE)
SCTE(DCE)
DTR(DTE)
DSR(DCE)
RTS(DTE)
DCD(DTE)
CTS(DCE)
DCD(DCE)
R1
D3
D2
D1
SCTE(DTE)
RXC(DCE)
TXC(DTE)
TXD(DTE)
TXC(DCE)
RXD(DCE)
MAX3172
MAX3174
R4
R3
R2
16 3
9 17
R1
D3
D2
D1
D4
MAX3170
M0
M1
M2
DCE/DTE
CTS(DTE)
RTS(DCE)
DSR(DTE)
DTR(DCE)
M0
M1
M2
DCE/DTE
MAX3171/MAX3173
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceivers
M0 M1 M2 DCE/DTE
TXD B
TXD A
RXD
RXD
DB-25 CONNECTOR
RXC SCTE B
RXC SCTE A
TXC B
TXC A
12 15 11 24 14 2
TXC B
TXC A
25
DCE/DTE
RXD
RXD
RXC
RXC
SG
18 21
M0 M1
TXD B
TXD A
SCTE B
SCTE A
7
SHIELD
RTS B
RTS A
1
CTS B
CTS A
DTR B
DTR A
DCD
DCD
23 20 19 4
DSR
DSR
DSR
DSR
CABLE WIRING FOR
MODE SELECTION
MODE
PIN 18 PIN 21
V.35
PIN 7 PIN 7
RS-449, V.36 N.C.
PIN 7
RS-232
PIN 7 N.C.
DCD
DCD
22 6
DTR B
DTR A
10 8
DCE
RTS B
RTS A
13 5
DTE
CTS B
CTS A
VCC
CABLE WIRING FOR
DCE/DTE SELECTION
MODE
PIN 25
DTE
PIN 7
DCE
N.C.
Figure 6. Cable-Selectable Multiprotocol DCE/DTE Port
V.10 Interface
BALANCED
INTERCONNECTING
CABLE
GENERATOR
A
LOAD
CABLE
RECEIVER
TERMINATION
A′
100Ω
MIN
B
B′
C
C′
Figure 7. Typical V.11 Interface
10
The V.10 interface (Figure 10) is an unbalanced singleended interface capable of driving a 450Ω load. 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 450Ω load. 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-
______________________________________________________________________________________
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceiver
3.25mA
A′
A
VZ
+10V
+3V
MAX3171
MAX3173
R5
30kΩ
-3V
-10V
MAX3171/MAX3173
IZ
R8
5kΩ
R6
10kΩ
RECEIVER
-3.25mA
S3
Figure 8. Receiver Input Impedance Curve
A′
R7
10kΩ
A
MAX3171
MAX3173
R5
30kΩ
R8
5kΩ
R4
30kΩ
B
B′
S5
R6
10kΩ
C′
RECEIVER
S4
GND
S3
Figure 11. V.10 Internal Resistance Network
R7
10kΩ
B′
R4
30kΩ
B
A′
A
MAX3171
MAX3173
R5
30kΩ
C′
R8
5kΩ
GND
R6
10kΩ
Figure 9. V.11 Termination and Internal Resistance Networks
RECEIVER
S3
GENERATOR
UNBALANCED
INTERCONNECTING
CABLE
A
LOAD
CABLE
TERMINATION
R7
10kΩ
RECEIVER
R4
30kΩ
A′
B′
B
C′
C
C′
Figure 10. Typical V.10/V.28 Interface
GND
Figure 12. V.28 Termination and Internal Resistance Networks
______________________________________________________________________________________
11
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
MAX3171/MAX3173
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceivers
TXD B
TXD A
RXD B
RXD A
RXC B SCTE B
RXC A SCTE A
TXC B
TXC A
12 15 11 24 14 2
TXC B
TXC A
DB-25 CONNECTOR
TXD B
TXD A
SCTE B
SCTE A
SG
LL A
RXD B
RXD A
RXC B
RXC 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
Figure 13. Multiprotocol DCE/DTE Port
Safe). To aid in rejecting system noise, the
MAX3171/MAX3173 V.10 receiver has 15mV (typ) hysteresis. Switch S3 in Figure 11 is open in V.10 mode to
disable the 5kΩ V.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 interface (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
12
Figure 12 is closed in V.28 mode to enable the 5kΩ V.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 lowfrequency signal (tB > 15µs), allowing glitch-free operation in unterminated systems at up to 64kbps. The
MAX3173 does not have this feature and can be operated 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
______________________________________________________________________________________
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceiver
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
MAX3171/MAX3173
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 14. DCE-to-DTE X.21 Interface
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) signal 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 generate 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 terminate the clock and data signals to support the V.11
protocol for cable termination. The control signals do
not need external termination.
______________________________________________________________________________________
13
MAX3171/MAX3173
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceivers
Pin Configuration
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.
Chip Information
TRANSISTOR COUNT: 1763
PROCESS: BiCMOS
TOP VIEW
V+ 1
28 C1+
C2+ 2
27 VCC
C2- 3
26 GND
V- 4
25 C1-
T1IN 5
T2IN 6
24 T1OUTA
MAX3171
MAX3173
23 T1OUTB
T3IN 7
22 T2OUTA
R1OUT 8
21 T2OUTB
R2OUT 9
20 T3OUTA/R1INA
R3OUT 10
19 T3OUTB/R1INB
M0 11
18 R2INB
M1 12
17 R2INA
M2 13
16 R3INA
DCE/DTE 14
15 R3INB
SSOP
14
______________________________________________________________________________________
+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceiver
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 ____________________ 15
© 2001 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
MAX3171/MAX3173
Package Information