MAXIM MAX3171, MAX3173 User Manual

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 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.

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

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.

CTS DSR RTSDTR LLDCD

PART TEMP. RANGE PIN-PACKAGE
MAX3171CAI 0°C to +70°C 28 SSOP
MAX3173CAI 0°C to +70°C 28 SSOP

RXD RXC TXDTXC SCTE

MAX3171
MAX3173

R2R3

13 5 10 8 22 6 23 20 19 4 1 7 1618 3 9 17 12 15 11 24 14 2

CTS B

CTS A

DSR B

DSR A

D3

R1

DCD B

DCD A

D2

DTR B

DTR A

D1

RTS B

RTS A

SHIELD

MAX3172
MAX3174

R4

SG

DB-25 CONNECTOR

R2R3

D4

LL A

RXD A

RXD B

RXC B

RXC A

D3

R1

TXC B

TXC A

SCTE B

SCTE A

D1D2

TXD B

MAX3170

TXD A

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= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at V

CC

= +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

V

CC

......................................................................-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 (V

CC

+ 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 (T

A

= +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

DC CHARACTERISTICS

Supply Current
(DCE Mode, Digital Inputs =
GND or V
Outputs Static)

Internal Power Dissipation P

V+ Output Voltage V+

V- Output Voltage 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 V

Input Low Voltage V

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

I

, Transmitter

CC

CC

D

IH

IL

IL

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

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 6.6

V.11/V.10 modes (no load) 4.4

V.11/V.10 modes (full load) 4.2

V.28 mode 5.55

No-cable mode 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 -4.2

T_IN ±1
M0, M1, M2, DCE / DTE = V
M0, M1, M2, DCE / DTE = GND 30 50 100

CC

2.0 V

0.8 V

±1Logic Input Current IIH, I

mA

mW

V

V

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= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at V

CC

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

LOGIC OUTPUTS (R_OUT)

Output High Voltage V

Output Low Voltage V

Rise or Fall Time tr, t

Output Leakage Current
(Receiver Output Three-Stated)

TRANSMITTER OUTPUTS

Output Leakage Current I

Data Rate

Receiver Glitch Rejection
(MAX3171 only)

Receiver Input Resistance R

Data Rate

V.11 TRANSMITTER

Unloaded Differential Output
Voltage

Loaded Differential Output
Voltage

Change in Magnitude of Output
Differential Voltage

Common-Mode Output Voltage V

Change in Magnitude of Output
Common-Mode Voltage

Short-Circuit Current I

Rise or Fall Time tr, t

Transmitter Input to Output t

Data Skew | t

Output-to-Output Skew t

Channel-to-Channel Skew 2ns

V.11 RECEIVER

Differential Threshold Voltage V

Input Hysteresis ∆V

V

V

∆V

∆V

PHL

PHL

OH

OL

Z

IN

ODO

ODL

OD

OC

OC

SC

, t

- t

SKEW

TH

I

I

10% to 90%, Figure 4 15 ns

f

R_OUT = GND 30 50 100

R_OUT = V

-0.25V ≤ V
no-cable mode

V.28 240

V.10 115

V.11 10 Mbps

Minimum pulse width passed 5

Minimum pulse width rejected 15

-10V ≤ VAB ≤ +10V, VA or VB grounded,
V.11/V.35, no-cable mode

-15V ≤ VA ≤ +15V, V.28 mode 3 5 7

MAX3171

MAX3173

R = 1.95kΩ, Figure 1 4.0 6.0 V

R = 50Ω, Figure 1 0.5 ✕ V

R = 50Ω, Figure 1 0.2 V

R = 50Ω, Figure 1 3.0 V

R = 50Ω, Figure 1 0.2 V

T_OUTA/B = GND 60 150 mA

10% to 90%, Figure 2 10 25 ns

f

Figure 2 50 80 ns

PLH

| Figure 2 2 10 ns

PLH

Figure 2 2 ns

-7V ≤ VCM ≤ +7V -200 -100 -25 mV

-7V ≤ VCM ≤ +7V 5 15 mV

TH

= 1.0mA VCC - 1.0 V

SOURCE

= 1.6mA 0.4 V

SINK

CC

≤ +0.25V, power off or

OUT

V.10/V.28 64

V.11 64

V.10/V.28 240

V.11 10 Mbps

-100 100 µA

20 40

ODO

±1

µA

kbps

µs

KΩ

kbps

V

MAX3171/MAX3173

+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceivers

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(VCC= 3.3V ±5%; C1 = C2 = 1µF, C3 = C4 = C5 = 3.3µF, and TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at V

CC

= +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.

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Receiver Input to Output t

Data Skew | t

PHL

P H L

, t

- t

MAX3171 5 10 15 µs

PLH

MAX3173 60 120 ns

MAX3171 0.5 4 µs

|

P LH

MAX3173 5 16 ns

V.10 TRANSMITTER

Unloaded Output Voltage

Loaded Output Voltage Swing V

Short-Circuit Current I

V

ODO

ODL

SC

Transmitter Rise or Fall Time tr, t

Transmitter Input to Output t

Data Skew | t

PHL

P H L

, t

- t

RL = 3.9kΩ, Figure 3 ±4.0 ±4.4 ±6.0 V

RL = 450Ω, Figure 3

T_OUTA = GND ±100 ±150 mA

RL = 450Ω, C

f

PLHRL

P LH

= 450Ω, C

| RL = 450Ω, C

V.10 RECEIVER

Threshold Voltage V

Input Hysteresis ∆V

Receiver Input to Output t

Data Skew | t

PHL

P H L

TH

TH

, t

- t

MAX3171, Figure 4 5 10 15 µs

PLH

MAX3173, Figure 4 60 120 ns

MAX3171, Figure 4 0.5 4 µs

|

P LH

MAX3173, Figure 4 5 16 ns

V.28 TRANSMITTER

Output Voltage Swing V

Short-Circuit Current I

O

SC

All transmitters loaded with RL = 3kΩ±5.0 ±5.4

No load ±6.5

T_OUTA = GND ±25 ±60 mA

RL = 3kΩ, CL = 2500pF, measured from +3V

Output Slew Rate SR

to -3V or from -3V to +3V, Figure 3

R

= 7kΩ, CL = 150pF, measured from +3V

L

to -3V or from -3V to +3V, Figure 3

Transmitter Input to Output t

Data Skew | t

PHL

P H L

, t

- t

Figure 3 1 µs

PLH

| Figure 3 100 ns

P LH

V.28 RECEIVER

Input Threshold Low V

Input Threshold High V

Input Hysteresis V

Propagation Delay t

Data Skew | t

PLH

P H L

IL

IH

HYS

, t

- t

MAX3171, Figure 4 5 10 15

PHL

MAX3173, Figure 4 200

MAX3171, Figure 4 0.5 4.0 µs

|

P LH

MAX3173, Figure 4 100 ns

= 100pF, Figure 3 2 µs

L

= 100pF, Figure 3 2 µs

L

=100pF, Figure 3 50 ns

L

✕

0.9
V

ODO

+25 +100 +300 mV

430

630

2.0 V

V

15 mV

V

V/µs

0.8 V

0.5 V

µs

MAX3171/MAX3173

+3.3V Multiprotocol 3Tx/3Rx

Software-Selectable Control Transceivers

_______________________________________________________________________________________ 5

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)

V

OUT+

V

OUT-

RL = 3k

Ω

-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)

V

OUT+

V

OUT-

RL = 450

Ω

-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

V.10/V.11 MODE SUPPLY CURRENT vs.

DATA RATE

250

FULL LOAD

200

150

100

SUPPLY CURRENT (mA)

50

NO LOAD

0

0.001 0.01 10k 100k0.1 1k 1000k
DATA RATE (kbps)

MAX3171 toc01

SUPPLY CURRENT (mA)

V.28 MODE SUPPLY CURRENT

vs. DATA RATE

80

70

60

50

40

30

FULL LOAD

20

NO LOAD

10

0

0.001 0.01 10k 100k0.1 1k 1000k
DATA RATE (kbps)

MAX3171 toc02

V.11 LOADED DIFFERENTIAL

OUTPUT VOLTAGE vs. TEMPERATURE

4

3

V

2

1

0

-1

OUTPUT VOLTAGE (V)

-2

-3

-4

OUT+

V

OUT-

-40 -15 10 35 60 85
TEMPERATURE (°C)

RL = 100

Ω

MAX3171 toc03

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 (R

L

= 3kΩ)

MAX3171 toc09

Figure 1. V.11 DC Test Circuit

Figure 2. V.11 AC Test Circuit

Test Circuits

V

OD

R

100Ω

V

R

OC

100pF

RxTx

50pF

100pF

MAX3171/MAX3173

+3.3V Multiprotocol 3Tx/3Rx

Software-Selectable Control Transceiver

_______________________________________________________________________________________ 7

Pin Description

Figure 3. V.10/V.28 Driver Test Circuit

Figure 4. V.10/V.28 Receiver Test Circuit

Test Circuits (continued)

Tx

C

L

PIN NAME FUNCTION

1V+

2 C2+

3C2-

4V-

5, 6, 7 T_IN Transmitter CMOS Inputs (T1IN, T2IN, T3IN)

Positive Supply Generated by the Charge Pump (connect to V+ pin of MAX3172/MAX3174).
Bypass V+ to ground with a 3.3µF ceramic capacitor.

Positive Terminal of the Inverting Charge-Pump Capacitor. Connect C2+ to C2- with a 1µF
ceramic capacitor.

Negative Terminal of the Inverting Charge-Pump Capacitor. Connect C2+ to C2- with a 1µF
ceramic capacitor.

Negative Supply Generated by the Charge Pump (connect to V- pin of MAX3172/MAX3174).
Bypass V- to ground with a 3.3µF ceramic capacitor.

R

L

Tx Rx

50pF

8, 9, 10 R_OUT Receiver CMOS Outputs (R1OUT, R2OUT, R3OUT)

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 V

28 C1+ Positive Terminal of the Voltage-Doubler Charge-Pump Capacitor. Connect C1+ to C1- with a

CC

Mode Select Inputs (M0, M1, M2). Internally pulled up to V
information.

DCE/DTE Mode Select Input. Logic level high selects DCE interface; logic level low selects
DTE interface. Internally pulled up to V

Negative Terminal of the Voltage-Doubler Charge-Pump Capacitor. Connect C1+ to C1- with
a 1µF ceramic capacitor.

+3.3V Supply Voltage (±5%). Bypass VCC to ground with a 3.3µF ceramic capacitor.

1µF ceramic capacitor.

CC

.

. See Table 1 for detailed

CC

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 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.

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.

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 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 V

CC

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 V

CC

). If the M0, M1, and M2
mode inputs are all unconnected, the MAX3171/
MAX3173 will enter no-cable mode.

Table 1. Mode Selection

Figure 5. Charge-Pump Connections

Z = High impedance

PROTOCOL

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

M2 M1 M0 DCE/DTE T1 T2 T3 R1 R2 R3

LOGIC INPUTS TRANSMITTERS RECEIVERS

MAX3171

1

MAX3173

C3

3.3µF

3.3µF

C2

1µF

C4

V+

2

C2+

3

C2-

4

V-

C1+

V

GND

C1-

28

27

CC

C5

26

3.3µF

25

C1
1µF

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 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.

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.

MAX3171/MAX3173

+3.3V Multiprotocol 3Tx/3Rx
Software-Selectable Control Transceivers

10 ______________________________________________________________________________________

V.10 Interface

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) V

ODO

voltage across

A' and C' when unloaded and a minimum of ±0.9

✕

V

ODO

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-

Figure 6. Cable-Selectable Multiprotocol DCE/DTE Port

Figure 7. Typical V.11 Interface

MAX3171
MAX3173

CTS(DTE)
RTS(DCE)

DSR(DTE)
DTR(DCE)

R2R3

R1

DCD(DTE)
DCD(DCE)

D3

DTR(DTE)
DSR(DCE)

D2

RTS(DTE)
CTS(DCE)

D1

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

DTE

CTS B

CTS A

DSR

DCE

RTS B

RTS A

DSR

DTR B

DTR A

DCD

DCD

DCD

DCD

DTR B

DSR

DTR A

DSR

RTS B

CTS B

RTS A

CTS A

M1M2M0

V

CC

SHIELD

DCE/DTE

SG

DB-25 CONNECTOR

MAX3172
MAX3174

R4

M2M1M0

M1M0

D4

DCE/DTE

DCE/DTE

RXD(DTE)
TXD(DCE)

RXD

TXD B

RXC(DTE)

SCTE(DCE)

R2R3

RXD

RXC

TXD A

SCTE B

R1

RXC

SCTE A

TXC(DTE)
TXC(DCE)

D3

TXC B

TXC B

SCTE(DTE)

RXC(DCE)

TXC A

SCTE B

RXC

TXC A

TXD(DTE)
RXD(DCE)

D1D2

TXD B

SCTE A

RXC

RXD

TXD A

RXD

MAX3170

M1M2M0

DCE/DTE

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.

GENERATOR

BALANCED

INTERCONNECTING

CABLE

A

B

C

CABLE

TERMINATION

A′

100Ω

MIN

B′

C′

LOAD

RECEIVER

MAX3171/MAX3173

+3.3V Multiprotocol 3Tx/3Rx

Software-Selectable Control Transceiver

______________________________________________________________________________________ 11

Figure 12. V.28 Termination and Internal Resistance Networks

Figure 11. V.10 Internal Resistance Network

Figure 10. Typical V.10/V.28 Interface

Figure 9. V.11 Termination and Internal Resistance Networks

Figure 8. Receiver Input Impedance Curve

I

-10V

-3.25mA

Z

-3V

+3V

3.25mA

V

+10V

A′

A

R5

30kΩ

R8
5kΩ

S3

B

B′

C′

GND

R4

30kΩ

10kΩ

R6

R7
10kΩ

MAX3171
MAX3173

RECEIVER

UNBALANCED

INTERCONNECTING

GENERATOR

CABLE

TERMINATION

A

A′

CABLE

LOAD

RECEIVER

A

A

′

R5

30k

30k

S4

Ω

R6

10k

Ω

R7

10k

R4

Ω

Ω

S5

Z

B

′

C

′

R8

5k

Ω

S3

B

GND

A

A

′

R5

30k

Ω

R8
5k

Ω

S3

B

B

′

30k

R6

10k

Ω

R7

10k

Ω

R4

Ω

MAX3171
MAX3173

RECEIVER

MAX3171
MAX3173

RECEIVER

C

C

′

C′

GND

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) 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

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

Figure 13. Multiprotocol DCE/

DTE

Port

MAX3171
MAX3173

CTS(DTE)
RTS(DCE)

DSR(DTE)
DTR(DCE)

R2R3

R1

DCD(DTE)
DCD(DCE)

D3

DTR(DTE)
DSR(DCE)

D2

RTS(DTE)
CTS(DCE)

D1

13 5 10 8 22 6 23 20 19 4 1 7 18 16 3 9 17 12 15 11 24 14 2

DTE

CTS B

CTS A

DSR B

DSR A

DCE

RTS B

RTS A

DTR B

DTR A

DCD B

DCD A

DCD B

DCD A

DTR B

DTR A

DSR B

DSR A

RTS B

CTS B

RTS A

CTS A

M1M2M0

DCE/DTE

SHIELD

RXD(DTE)

TXD(DCE)

LL(DTE)
LL(DCE)

MAX3172
MAX3174

R4

D4

DCE/DTE

M2M1M0

SG

LL A

DB-25 CONNECTOR

LL A

RXC(DTE)

SCTE(DCE)

RXD B

RXD A

TXD B

TXD A

R2R3

RXC B

SCTE B

R1

RXC A

SCTE A

TXC(DTE)
TXC(DCE)

D3

TXC B

TXC B

SCTE(DTE)

RXC(DCE)

TXC A

SCTE B

TXC A

RXC B

TXD(DTE)
RXD(DCE)

D1D2

TXD B

SCTE A

RXC A

RXD B

TXD A

RXD A

MAX3170

M1M2M0

M1M2M0

DCE/DTE

DCE/DTE

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.

MAX3171/MAX3173

+3.3V Multiprotocol 3Tx/3Rx

Software-Selectable Control Transceiver

______________________________________________________________________________________ 13

Figure 14. DCE-to-DTE X.21 Interface

SERIAL

CONTROLLER

DTE

MAX3170

MAX3172
MAX3174

MAX3174

DCE

MAX3170MAX3172

SERIAL

CONTROLLER

TXD

SCTE

TXC

RXC

RXD

RTS

DTR

DCD

D1

D2

D3

R1

R2

R3

LL

MAX3171
MAX3173

D1

D2

D3

R1

103Ω

103Ω

103Ω

D4

R4

SCTE

TXD

TXC

RXC

RXD

LL

RTS

DTR

DCD

103Ω

103Ω

R3

R2

R1

D3

D2

D1

R4

D4

MAX3171
MAX3173

R3

R2

R1

D3

TXD

SCTE

TXC

RXC

RXD

LL

RTS

DTR

DCD

DSR

CTS

R2

R3

DSR

CTS

D2

D1

DSR

CTS

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+

V

CC

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

MAX3171/MAX3173

+3.3V Multiprotocol 3Tx/3Rx

Software-Selectable Control Transceiver

SSOP.EPS