Maxim MAX3140EEI Datasheet

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General Description

The MAX3140 is a complete universal asynchronous
receiver-transmitter (UART) and a true fail-safe RS­485/RS-422 transceiver combined in a single 28-pin
QSOP package for space-, cost-, and power-con­strained applications. The MAX3140 saves additional
board space as well as microcontroller (µC) I/O pins by
featuring an SPI™/QSPI™/MICROWIRE™-compatible
serial interface. It is pin-programmable for configuration
in all RS-485/RS-422 networks.

The MAX3140 includes a single RS-485/RS-422 driver
and receiver featuring true fail-safe circuitry, which
guarantees a logic-high receiver output when the
receiver inputs are open or shorted. This feature pro­vides immunity to faults without requiring complex ter­mination. The MAX3140 provides software-selectable
control of half- or full-duplex operation, data rate, slew
rate, and transmitter and receiver phase. The RS-485
driver slew rate is programmable to minimize EMI and
results in maximum data rates of 115kbps, 500kbps,
and 10Mbps. Independent transmitter/receiver phase
control enables software correction of twisted-pair
polarity reversal. A 1/8-unit-load receiver input imped­ance allows up to 256 transceivers on the bus.

The MAX3140’s UART includes an oscillator circuit
derived from an external crystal, and a baud-rate gen­erator with software-programmable divider ratios for all
common baud rates from 300 baud to 230k baud. The
UART features an 8-word-deep receive FIFO that mini­mizes processor overhead and provides a flexible inter­rupt with four maskable sources, including address
recognition on 9-bit networks. Two control lines are
included for hardware handshaking—one input and
one output.

The MAX3140 operates from a single +5V supply and
typically consumes only 645µA with the receiver active.
Hardware-invoked shutdown reduces supply current to
only 20µA. The UART and RS-485/RS-422 functions can
be used together or independently since the two func­tions share only supply and ground connections (the
MAX3140 is hardware- and software-compatible with the
MAX3100 and MAX3089).

Applications

Industrial-Control Transceivers for EMI­Local Area Networks Sensitive Applications

HVAC and Building Control Embedded Systems
Point-of-Sale Devices Intelligent Instrumentation

Features

♦ Integrated UART and RS-485/RS-422 Transceiver

in a Single 28-Pin QSOP

♦ SPI/MICROWIRE-Compatible Interface Saves µC

I/O Pins

♦ True Fail-Safe Receiver Output Eliminates

Complex Network Termination

♦ Pin-Programmable RS-485/RS-422 Features

Half/Full-Duplex Operation
Slew-Rate Limiting for Reduced EMI
115kbps/500kbps/10Mbps Data Rates
Receiver/Transmitter Phase for Twisted-Pair

Polarity Reversal

♦ Full-Featured UART

Programmable Up to 230k baud with a

3.6864MHz Crystal

8-Word Receive FIFO Minimizes Processor

Overhead

9-Bit Address-Recognition Interrupt

♦ Allows Up to 256 Transceivers on the Bus
♦ Low 20µA Hardware Shutdown Mode
♦ Hardware/Software-Compatible with MAX3100

and MAX3089

MAX3140

SPI/MICROWIRE-Compatible UART with Integrated

True Fail-Safe RS-485/RS-422 Transceivers

________________________________________________________________

Maxim Integrated Products

1

19-1453; Rev 0; 6/99

PART

MAX3140CEI
MAX3140EEI -40°C to +85°C

0°C to +70°C

TEMP. RANGE PIN-PACKAGE

28 QSOP
28 QSOP

Ordering Information

SPI/QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.

Pin Configuration appears at end of data sheet.

Typical Application Circuit

CS

SCLK

SPI/

MICRO-

WIRE

DIN

DOUT

µP

UART

IRQ

H/FSRL

R

t

HALF/FULL-DUPLEX

RS-485/RS-422

R

t

TXP

CONTROL

LOGIC

RS-485
RS-422

RXP

MAX3140

MAX3140

SPI/MICROWIRE-Compatible UART with Integrated
True Fail-Safe RS-485/RS-422 Transceivers

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VCC= +5V ±5%, DE = VCC, RE = GND, SHDN = VCC, f

XTL

= 1.8432MHz, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values

are measured with V

CC

= +5V, UART configured for 9600 baud, TA= +25°C.) (Note 1)

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.

VCCto GND ..........................................................................+6V

Input Voltage to GND (CS, SHDN, X1, CTS, RX, DIN, SCLK,

RE, DE, H/F, SRL, TXP, RXP, Dl).............-0.3V to (V

CC

+ 0.3V)

Output Voltage to GND

DOUT, RTS, TX, X2, RO...........................-0.3V to (V

CC

+ 0.3V)

IRQ ........................................................................-0.3V to +6V

Driver Output Voltage (Y, Z) ...............................................±13V

Receiver Input Voltage, Half Duplex (Y, Z)......................... ±13V

Receiver Input Voltage, Full Duplex (A, B) .........................±25V

TX, RTS Output Current ...................................................100mA

X2, DOUT, IRQ Short-Circuit Duration

(to V

CC

or GND)......................................................Continuous

Continuous Power Dissipation (T

A

= +70°C)

28-pin QSOP (derate 10.8mW/°C above +70°C)..........860mW

Operating Temperature Ranges

MAX3140CEI .......................................................0°C to +70°C

MAX3140EEI ....................................................-40°C to +85°C

Storage Temperature Range.............................-65°C to +150°C

Lead Temperature (soldering, 10sec).............................+300°C

I

SOURCE

= 5mA; DOUT, RTS

SHDN = GND or SHDNi bit = 1;
DE = GND; RE = V

CC

SHDN = GND or SHDNi bit = 1

CONDITIONS

VCC- 0.5

pF5C

IN2

Input Capacitance

µA±1I

LKG1

Input Leakage Current

mV250V

HYST2

Input Hysteresis

V0.3V

CC

V

IL2

Input Low Voltage

V0.7V

CC

V

IH2

Input High Voltage

pF5C

IN1

Input Capacitance

25

V0.2V

CC

V

IL1

Input Low Voltage

V0.7V

CC

V

IH1

Input High Voltage

0.64 1.6

0.7 1.9

µA20

I

CC

SHDN

(FULL)

Supply Current with Both
RS-485 Transceiver and UART
Shut Down

0.74 2

mA

0.69 1.8

I

CC

Supply Current

mA0.47 1

I

CC

SHDN

UART

Supply Current with Only UART
Shut Down

UNITSMIN TYP MAXSYMBOLPARAMETER

I

SINK

= 4mA; DOUT, RTS

I

SOURCE

= 10mA; TX only

0.4

V

VCC- 0.5

V

OH1

Output High Voltage

V4.75 5.25V

CC

Supply Voltage

VX1= 0 or V

CC

µA

2

I

IN1

Input Current

SHDNi bit = 0
SHDNi bit = 1

I

SINK

= 25mA; TX only

V

0.9

V

OL1

Output Low Voltage

CS = VCC; D

OUT

only

µA

5

I

LKG2

Output Leakage ±1

C

OUT1

Output Capacitance pF

SHDN = VCC;
SHDNi bit = 0,
no load

DE = V

CC

DE = GND
DE = V

CC

DE = GND

SRL = V

CC

SRL = GND
or open

UART OUTPUTS (DOUT, TX, RTS)

UART LOGIC INPUTS (DIN, SCLK, CS, SHDN, CTS, RX)

UART OSCILLATOR INPUT (X1)

POWER SUPPLY

MAX3140

SPI/MICROWIRE-Compatible UART with Integrated

True Fail-Safe RS-485/RS-422 Transceivers

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VCC= +5V ±5%, DE = VCC, RE = GND, SHDN = VCC, f

XTL

= 1.8432MHz, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values

are measured with V

CC

= +5V, UART configured for 9600 baud, TA= +25°C.) (Note 1)

R = 50Ω or R = 27Ω, Figure 1

R = 50Ω or R = 27Ω, Figure 1 (Note 2)

R = 27Ω (RS-422), Figure 1

R = 50Ω (RS-422), Figure 1

No load, Figure 1

V

IRQ

= V

CC

I

SINK

= 4mA

R = 50Ω or R = 27Ω, Figure 1 (Note 2)

CONDITIONS

V3V

OC

Common-Mode Output
Voltage

V0.2∆V

OD

Change in Magnitude of
Differential Output Voltage

V

1.5

V

OD2

Differential Output Voltage 2.0

5V

OD1

pF5C

OUT2

Output Capacitance

µA±1I

LKG3

Output Leakage

V0.4V

OL2

Output Low Voltage

V0.2∆V

OC

Change In Magnitude of
Common-Mode Voltage

UNITSMIN TYP MAXSYMBOLPARAMETER

(Note 3)

H/F, TXP, RXP, internal pull-down

DE, DI, RE

SRL = VCCor unconnected

DE, Dl, RE, H/F, TXP, RXP

DE, Dl, RE

SRL = GND (Note 3)

SRL = V

CC

V

0.4 · V

CC

0.6 · V

CC

V

IM2

SRL Input Middle Voltage

VVCC- 0.8V

IH2

SRL Input High Voltage

µA

10 40I

IN2

Input Current

±2I

IN1

mV100V

HYS

DI Input Hysteresis

V0.8V

IL1

Input Low Voltage

2.0

µA

-75

I

IN3

SRL Input Current

75

V0.8V

IL2

SRL Input Low Voltage

(Note 4)

DE = GND

VCC= GND or 5.25V

DE = GND

250

-250

µA

125

I

O

Full-Duplex Output Leakage
(Y and Z)

µA

-75

I

IN4

125

Full-Duplex Input Current
(A and B)

mA

±25

I

OSD

Short-Circuit Output Current

-7V ≤ VCM≤ +12V mV-200 -125 -50V

TH

mV25∆V

TH

Input Hysteresis

Differential Threshold Voltage

I

SINK

= 4mA, VID= -200mV

I

SOURCE

= 4mA, VID= -50mV

0.4V ≤ VO≤ 2.4V

V0.4V

OL

VVCC- 1.5V

OH

µA±1I

OZR

Output High Voltage

Three-State Output Current

Output Low Voltage

-7V ≤ VCM≤ 12V
0 ≤ VRO≤ V

CC

kΩ96R

IN

mA±7 ±95I

OSR

Output Short-Circuit Current

Input Resistance

VIN= 12V
VIN= -7V

VCC= GND or 5.25V

VIN= 12V
VIN= -7V -100

-7V ≤ V

OUT

≤ V

CC

0 ≤ V

OUT

≤ 12V

0 ≤ V

OUT

≤ V

CC

H/F, TXP, RXP

V

2.4

V

IH1

Input High Voltage

UART IRQ OUTPUT (Open Drain)

RS-485 DRIVER

RS-485 RECEIVER

MAX3140

SPI/MICROWIRE-Compatible UART with Integrated
True Fail-Safe RS-485/RS-422 Transceivers

4 _______________________________________________________________________________________

UART SWITCHING CHARACTERISTICS

(VCC= +5V ±5%, f

XTL

= 1.8432MHz, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are measured with VCC= +5V,

UART configured for 9600 baud, T

A

= +25°C.) (Note 1)

CONDITIONS UNITSMIN TYP MAXSYMBOLPARAMETER

C

LOAD

= 100pF ns100t

DV

CS Low to DOUT Valid

C

LOAD

= 100pF, RCS= 10kΩ ns100t

TR

CS High to DOUT Tri-State

ns0t

CSH

CS to SCLK Hold Time

ns100t

CSS

CS to SCLK Setup Time

ns100t

DS

DIN to SCLK Setup Time

ns238t

CP

SCLK Period

ns0t

DH

DIN to SCLK Hold Time

C

LOAD

= 100pF ns100t

DO

SCLK Fall to DOUT Valid

ns100t

CL

SCLK Low Time

ns200t

CS1

CS Rising Edge to SCLK
Rising

ns100t

CS0

SCLK Rising Edge to CS
FaIling

TX, RTS, DOUT; C

LOAD

= 100pF

ns10t

r

Output Rise Time

TX, RTS, DOUT, IRQ; C

LOAD

= 100pF

ns10t

f

Output Fall Time

ns200t

CSW

CS High Pulse Width

ns100t

CH

SCLK High Time

UART AC TIMING (Figure 1)

MAX3140

SPI/MICROWIRE-Compatible UART with Integrated

True Fail-Safe RS-485/RS-422 Transceivers

_______________________________________________________________________________________ 5

SWITCHING CHARACTERISTICS—SRL = Unconnected

(VCC= +5V ±5%, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at VCC= +5V and TA= +25°C.)

500 2030 2600t

DPHL

PARAMETER SYMBOL MIN TYP MAX UNITS

Driver Disable Time from Low t

DLZ

100 ns

Driver Enable to Output Low t

DZL

3500 ns

Driver Enable to Output High t

DZH

3500 ns

Maximum Data Rate f

MAX

115 kbps

Driver Disable Time from High t

DHZ

100 ns

Receiver Input to Output

t

RPLH

,

t

RPHL

127 200 ns

|

t

RPLH

- t

RPHL

|

Differential

Receiver Skew

t

RSKD

3±30ns

Receiver Enable to Output Low t

RZL

20 50 ns

Driver Output Skew

|

t

DPLH

- t

DPHL

|

Driver Input to Output

t

DPLH

500 2030 2600

ns

t

DSKEW

-3 ±200 ns

Driver Rise or Fall Time tDR, t

DF

667 1320 2500 ns

Receiver Enable to Output High t

RZH

20 50 ns

Receiver Disable Time from Low t

RLZ

20 50 ns

Receiver Disable Time from
High

t

RHZ

20 50 ns

Time to Shutdown t

SHDN

50 200 600 ns

Driver Enable from Shutdown to
Output High

t

DZH(SHDN)

6000 ns

Driver Enable from Shutdown to
Output Low

t

DZL(SHDN)

6000 ns

Receiver Enable from Shutdown
to Output High

t

RZH(SHDN)

3500 ns

Receiver Enable from Shutdown
to Output Low

t

RZL(SHDN)

3500 ns

CONDITIONS

Figures 2 and 8, CL= 100pF, S2 closed

Figures 4 and 6, CL= 15pF, S1 closed

Figures 2 and 8, CL= 100pF, S1 closed

Figures 4 and 6, CL= 100pF, S1 closed

Figures 4 and 6, CL= 100pF, S2 closed

Figures 4 and 6, CL= 15pF, S2 closed
Figures 7 and 9, |V

ID

|

≥ 2.0V,

rise and fall time of V

ID

≤ 15ns

Figures 2 and 8, CL= 100pF, S2 closed
(Note 5)

Figures 7 and 9, |V

ID

|

≥ 2.0V,

rise and fall time of V

ID

≤ 15ns

Figures 2 and 8, CL= 100pF, S1 closed

Figures 4 and 6, CL= 15pF, S2 closed

Figures 4 and 6, CL= 15pF, S1 closed

Figures 2 and 8, CL= 100pF, S2 closed

Figures 3 and 5, R

DIFF

= 54Ω,

CL1= CL2= 100pF

Figures 2 and 8, CL= 100pF, S1 closed

Figures 3 and 5, R

DIFF

= 54Ω,

CL1= CL2= 100pF
Figures 3 and 5, R

DIFF

= 54Ω,

CL1= CL2= 100pF

MAX3140

SPI/MICROWIRE-Compatible UART with Integrated
True Fail-Safe RS-485/RS-422 Transceivers

6 _______________________________________________________________________________________

SWITCHING CHARACTERISTICS—SRL = V

CC

(VCC= +5V ±5%, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at VCC= +5V and TA= +25°C.)

250 720 1000

Receiver Enable from Shutdown
to Output Low

t

RZL(SHDN)

3500 nsFigures 2 and 8, CL= 100pF, S1 closed

t

DPHL

PARAMETER SYMBOL MIN TYP MAX UNITS

Driver Disable Time from Low t

DLZ

100 ns

Driver Enable to Output Low t

DZL

2500 ns

Driver Enable to Output High t

DZH

2500 ns

Maximum Data Rate f

MAX

500 kbps

Driver Disable Time from High t

DHZ

100 ns

Receiver Input to Output

t

RPLH

,

t

RPHL

127 200 ns

|

t

RPLH

- t

RPHL

|

Differential

Receiver Skew

t

RSKD

3±30ns

Receiver Enable to Output Low t

RZL

20 50 ns

Driver Output Skew

|

t

DPLH

- t

DPHL

|

Driver Input to Output

t

DPLH

250 720 1000

ns

t

DSKEW

-3 ±100 ns

Driver Rise or Fall Time t

DR, tDF

200 530 750 ns

Receiver Enable to Output High t

RZH

20 50 ns

Receiver Disable Time from Low t

RLZ

20 50 ns

Receiver Disable Time from
High

t

RHZ

20 50 ns

Time to Shutdown t

SHDN

50 200 600 ns

Driver Enable from Shutdown to
Output High

t

DZH(SHDN)

4500 ns

Driver Enable from Shutdown to
Output Low

t

DZL(SHDN)

4500 ns

Receiver Enable from Shutdown
to Output High

t

RZH(SHDN)

3500 ns

CONDITIONS

Figures 2 and 8, CL= 100pF, S2 closed

Figures 4 and 6, CL= 15pF, S1 closed

Figures 2 and 8, CL= 100pF, S1 closed

Figures 4 and 6, CL= 100pF, S1 closed

Figures 4 and 6, CL= 100pF, S2 closed

Figures 4 and 6, CL= 15pF, S2 closed
Figures 7 and 9, |V

ID

|

≥ 2.0V,

rise and fall time of V

ID

≤ 15ns

Figures 2 and 8, CL= 100pF, S2 closed
(Note 5)

Figures 7 and 9, |V

ID

|

≥ 2.0V,

rise and fall time of V

ID

≤ 15ns

Figures 2 and 8, CL= 100pF, S1 closed

Figures 4 and 6, CL= 15pF, S2 closed

Figures 4 and 6, CL= 15pF, S1 closed

Figures 2 and 8, CL= 100pF, S2 closed

Figures 3 and 5, R

DIFF

= 54Ω,

CL1= CL2= 100pF
Figures 3 and 5, R

DIFF

= 54Ω,

C

L1

= CL2= 100pF

Figures 3 and 5, R

DIFF

= 54Ω,

CL1= CL2= 100pF

MAX3140

SPI/MICROWIRE-Compatible UART with Integrated

True Fail-Safe RS-485/RS-422 Transceivers

_______________________________________________________________________________________ 7

SWITCHING CHARACTERISTICS—SRL = GND

(VCC= +5V ±5%, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at VCC= +5V and TA= +25°C.)

PARAMETER SYMBOL MIN TYP MAX UNITS

Driver Disable Time from Low t

DLZ

100 ns

Driver Enable to Output Low t

DZL

150 ns

Driver Enable to Output High t

DZH

150 ns

Maximum Data Rate f

MAX

10 Mbps

Driver Disable Time from High t

DHZ

100 ns

Receiver Input to Output

t

RPLH

,

t

RPHL

106 150 ns

|

t

RPLH

- t

RPHL

|

Differential

Receiver Skew

t

RSKD

0±10ns

Receiver Enable to Output Low t

RZL

20 50 ns

Driver Output Skew

|

t

DPLH

- t

DPHL

|

Driver Input to Output

t

DPLH

34 60

ns

t

DSKEW

-2.5 ±10 ns

Driver Rise or Fall Time t

DR, tDF

14 25 ns

Receiver Enable to Output High t

RZH

20 50 ns

Receiver Disable Time from Low t

RLZ

20 50 ns

Receiver Disable Time from
High

t

RHZ

20 50 ns

Time to Shutdown t

SHDN

50 200 600 ns

Driver Enable from Shutdown to
Output High

t

DZH(SHDN)

250 ns

Driver Enable from Shutdown to
Output Low

t

DZL(SHDN)

250 ns

Receiver Enable from Shutdown
to Output High

t

RZH(SHDN)

3500 ns

34 60

CONDITIONS

Figures 2 and 8, CL= 100pF, S2 closed

Figures 4 and 6, CL= 15pF, S1 closed

Figures 2 and 8, CL= 100pF, S1 closed

Figures 4 and 6, CL= 100pF, S1 closed

Figures 4 and 6, CL= 100pF, S2 closed

Figures 4 and 6, CL= 15pF, S2 closed
Figures 7 and 9, |V

ID

|

≥ 2.0V,

rise and fall time of V

ID

≤ 15ns

Figures 2 and 8, CL= 100pF, S2 closed
(Note 5)

Figures 7 and 9, |V

ID

|

≥ 2.0V,

rise and fall time of V

ID

≤ 15ns

Figures 2 and 8, CL= 100pF, S1 closed

Figures 4 and 6, CL= 15pF, S2 closed

Figures 4 and 6, CL= 15pF, S1 closed

Figures 2 and 8, CL= 100pF, S2 closed

Figures 3 and 5, R

DIFF

= 54Ω,

CL1= CL2= 100pF

Receiver Enable from Shutdown
to Output Low

Figures 3 and 5, R

DIFF

= 54Ω,

CL1= CL2= 100pF

t

RZL(SHDN)

3500

Figures 3 and 5, R

DIFF

= 54Ω,

CL1= CL2= 100pF

nsFigures 2 and 8, CL= 100pF, S1 closed

t

DPHL

Note 1: All currents into the device are positive; all currents out of the device are negative. All voltages are referred to device

ground unless otherwise noted.

Note 2: ∆V

OD

and ∆VOCare the changes in VODand VOC, respectively, when the Dl input changes state.

Note 3: The SRL pin is internally biased to V

CC

/2 by a 100kΩ/100kΩ resistor-divider. It is guaranteed to be VCC/2 if left unconnected.

Note 4: Maximum current level applies to peak current just prior to foldback-current limiting; minimum current level applies during

current limiting.

Note 5: The device is put into shutdown by bringing RE high and DE low. If the enable inputs are in this state for less than 50ns, the

device is guaranteed not to enter shutdown. If the enable inputs are in this state for at least 600ns, the device is guaranteed
to have entered shutdown.

MAX3140

SPI/MICROWIRE-Compatible UART with Integrated
True Fail-Safe RS-485/RS-422 Transceivers

8 _______________________________________________________________________________________

Typical Operating Characteristics

(VCC= +5V, TA = +25°C, unless otherwise noted.)

1000

900

0

-40 -20 40 60 100

UART SUPPLY CURRENT

vs. TEMPERATURE

200
100

800
700

MAX3140-01

TEMPERATURE (°C)

SUPPLY CURRENT (µA)

020 80

600
500

400
300

1.8432MHz CRYSTAL
TRANSMITTING AT 115.2 kbps

10

9

0

-40 -20 40 60 100

UART SHUTDOWN CURRENT

vs. TEMPERATURE

2
1

8
7

MAX3140-02

TEMPERATURE (°C)

SHUTDOWN CURRENT (µA)

020 80

6
5

4
3

1.8432MHz CRYSTAL

400

50

100 10k

1000

100k 1M

UART SUPPLY CURRENT

vs. BAUD RATE

150

100

MAX3140-03

BAUD RATE (bps)

SUPPLY CURRENT (µA)

200

250

350

300

TRANSMITTING

1.8432 MHz
CRYSTAL

STANDBY

700

600

0

01 3

4

5

UART SUPPLY CURRENT vs.

EXTERNAL CLOCK FREQUENCY

100

500

MAX3140-04

EXTERNAL CLOCK FREQUENCY (MHz)

SUPPLY CURRENT (µA)

2

400

300

200

0

10

05

RS-485 OUTPUT CURRENT

vs. RECEIVER OUTPUT LOW VOLTAGE

20

60

MAX3140-07

OUTPUT LOW VOLTAGE (V)

OUTPUT CURRENT (mA)

3

40

30

2

50

14

90
80

0

0 0.20.1 0.6 0.7

0.8

1.0

TX, RTS, DOUT OUTPUT CURRENT

vs. OUTPUT LOW VOLTAGE

10

70

MAX3140-05

OUTPUT LOW VOLTAGE (V)

OUTPUT SINK CURRENT (mA)

0.3 0.50.4 0.9

60
50

40
30
20

RTS

TX

DOUT

300

-60 100

RS-485 TRANSCEIVER NO-LOAD

SUPPLY CURRENT vs. TEMPERATURE

350
325

525

MAX3140-06

TEMPERATURE (°C)

NO-LOAD SUPPLY CURRENT (µA)

40

450
425

375

400

060

500
475

-40 -20 20 80

A: SRL = GND

B: SRL = OPEN OR V

CC

A

A

B

DE = V

CC

DE = GND

B

0

5

05

RS-485 OUTPUT CURRENT

vs. RECEIVER OUTPUT HIGH VOLTAGE

10

30

MAX3140-08

OUTPUT HIGH VOLTAGE (V)

OUTPUT CURRENT (mA)

3

20

15

2

25

14

0

2

-60 100

RS-485 TRANSCEIVER SHUTDOWN

CURRENT vs. TEMPERATURE

4

6

20

MAX3140-09

TEMPERATURE (°C)

SHUTDOWN CURRENT (nA)

40

12

14

10

8

060

16

18

-40 -20 20 80

MAX3140

SPI/MICROWIRE-Compatible UART with Integrated

True Fail-Safe RS-485/RS-422 Transceivers

_______________________________________________________________________________________

9

0.10

0.15

-60 80 100

RS-485 RECEIVER OUTPUT LOW VOLTAGE

vs. TEMPERATURE

0.20

0.50

MAX3140-10

TEMPERATURE (°C)

OUTPUT LOW VOLTAGE (V)

20

0.40

0.35

0.30

0.25

040

0.45

-40 -20 60

IRO = 8mA

3.8

3.9

-60 80 100

RS-485 RECEIVER OUTPUT HIGH VOLTAGE

vs. TEMPERATURE

4.0

4.5

MAX3140-11

TEMPERATURE (°C)

OUTPUT HIGH VOLTAGE (V)

20

4.3

4.2

4.1

040

4.4

-40 -20 60

IRO = 8mA

115

-60 100

RS-485 RECEIVER PROPAGATION DELAY

(500kbps MODE) vs. TEMPERATURE

120

140

MAX3140-12

TEMPERATURE (°C)

PROPAGATION DELAY (ns)

40

130

125

060

135

-40 -20 20 80

C

LOAD

= 100pF

94

-60 100

RS-485 RECEIVER PROPAGATION DELAY

(10Mbps MODE) vs. TEMPERATURE

98
96

112

MAX3140-13

TEMPERATURE (°C)

PROPAGATION DELAY (ns)

40

106
104

100

102

060

110
108

-40 -20 20 80

C

LOAD

= 100pF

20

25

-60 100

RS-485 DRIVER PROPAGATION DELAY

(10Mbps MODE) vs. TEMPERATURE

30

60

MAX3140-16

TEMPERATURE (°C)

PROPAGATION DELAY (ns)

40

45

50

40
35

060

55

-40 -20 20 80

Rt = 54Ω

1.90

-60 100

RS-485 DRIVER PROPAGATION DELAY

(115kbps MODE) vs. TEMPERATURE

1.95

2.20

MAX3140-14

TEMPERATURE (°C)

PROPAGATION DELAY (µs)

40

2.10

2.00

2.05

060

2.15

-40 -20 20 80

Rt = 54Ω

520

560

-60 100

RS-485 DRIVER PROPAGATION DELAY

(500kbps MODE) vs. TEMPERATURE

600

640

920

MAX3140-15

TEMPERATURE (°C)

PROPAGATION DELAY (ns)

40

760

800

720
680

060

840

880

-40 -20 20 80

Rt = 54Ω

1.83

1.84

-60 100

RS-485 DRIVER DIFFERENTIAL

OUTPUT VOLTAGE vs. TEMPERATURE

1.85

1.90

MAX3140-17

TEMPERATURE (°C)

OUTPUT VOLTAGE (V)

40

1.88

1.87

1.86

060

1.89

-40 -20 20 80

Rt = 54Ω

100

0.01
01

RS-485 DRIVER OUTPUT CURRENT

vs. DIFFERENTIAL OUTPUT VOLTAGE

0.1

10

1

MAX3140-18

DIFFERENTIAL OUTPUT VOLTAGE (V)

OUTPUT CURRENT (mA)

2345

Typical Operating Characteristics (continued)

(VCC= +5V, TA = +25°C, unless otherwise noted.)

MAX3140

SPI/MICROWIRE-Compatible UART with Integrated
True Fail-Safe RS-485/RS-422 Transceivers

10 ______________________________________________________________________________________

Typical Operating Characteristics (continued)

(VCC= +5V, TA = +25°C, unless otherwise noted.)

0

20

40

60

80

100

120

140

OUTPUT CURRENT vs.

RS-485 DRIVER OUTPUT LOW VOLTAGE

MAX3140-19

OUTPUT LOW VOLTAGE (V)

OUTPUT CURRENT (mA)

024681012

0

-10

-20

-30

-40

-50

-60

-70

-80

-90

-100

-8 -2

OUTPUT CURRENT vs.

RS-485 DRIVER OUTPUT HIGH VOLTAGE

MAX3140-20

OUTPUT HIGH VOLTAGE (V)

OUTPUT CURRENT (mA)

642-6 -4 0

50ns/div

VA - V

B

(2V/div)

RO

(5V/div)

MAX3140-21

RS-485 RECEIVER PROPAGATION DELAY

(SRL = GND)

50ns/div

VA - V

B

(2V/div)

RO

(5V/div)

MAX3140-22

RS-485 RECEIVER PROPAGATION DELAY

(SRL = OPEN OR V

CC

)

2µs/div

RS-485 DRIVER PROPAGATION DELAY

(SRL = OPEN)

DI

(5V/div)

V

Y

- V

Z

(2.5V/div)

MAX3140-23

500ns/div

RS-485 DRIVER PROPAGATION DELAY

(SRL = V

CC

)

DI

(5V/div)

V

Y

- V

Z

(2.5V/div)

MAX3140-24

50ns/div

RS-485 DRIVER PROPAGATION DELAY

(SRL = GND)

DI

(5V/div)

V

Y

- V

Z

(2.5V/div)

MAX3140-25

MAX3140

SPI/MICROWIRE-Compatible UART with Integrated

True Fail-Safe RS-485/RS-422 Transceivers

______________________________________________________________________________________ 11

Pin Description

UART Crystal Connection. Leave X2 unconnected for external clock. See the

Crystals,

Oscillators, and Ceramic Resonators

section.

X21 1

2

UART Crystal Connection. X1 also serves as an external clock input. See the

Crystals,

Oscillators, and Ceramic Resonators

section.

X12

3

4

UART Request-to-Send Active-Low Output. Controlled by the RTS bit. Use to control the dri­ver enable in RS-485 networks.

RTS

4

UART Clear-to-Send Active-Low Input. Read via the CTS bit.

CTS

3

5

6 UART Asynchronous Serial-Data (transmitter) OutputTX6

7

8 GroundGND8

RS-485 Half/Full-Duplex Selector Pin. Connect H/F to VCCfor half-duplex mode; connect H/F
to GND or leave it unconnected for full-duplex mode.

H/F

7

UART Asynchronous Serial-Data (receiver) Input. The serial information received from the modem
or RS-232/RS-485 receiver. A transition on RX while in shutdown generates an interrupt (Table 1).

RX5

9

10

RS-485 Receiver Output Enable. Drive RE low to enable RO; RO is high impedance when RE
is high. Drive RE high and DE low to enter low-power shutdown mode.

RE

10

11

12

RS-485 Driver Input. With DE high, a low on DI forces noninverting output low and inverting
output high. Similarly, a high on DI forces noninverting output high and inverting output low.

DI12

RS-485 Driver Output Enable. Drive DE high to enable driver outputs. These outputs are high
impedance when DE is low. Drive RE high and DE low to enter low-power shutdown mode.

DE11

13

14 No Connection. Not internally connected.N.C.14

15

— RS-485 Noninverting Driver OutputY16

RS-485 Transmitter Phase. Connect TXP to GND or leave it floating for normal transmitter
phase/polarity. Connect TXP to VCCto invert the transmitter phase/polarity.

TXP15

RS-485 Transceiver Slew-Rate-Limit Selector Pin. Connect SRL to GND for a 10Mbps com­munication rate, connect SRL to VCCfor a 500kbps rate, or leave SRL unconnected for a
115kbps rate.

SRL13

RS-485 Receiver Output. When RE is low and if A - B ≥ -50mV, RO will be high; if A - B ≤

-200mV, RO will be low.

RO9

16
17 No Connection. Not internally connected.N.C.17
—
18 RS-485 Inverting Receiver Input and RS-485 Inverting Driver Output*Z—

RS-485 Inverting Driver OutputZ18

—
19 RS-485 Receiver Input Resistors*B—
—
20 RS-485 Receiver Input Resistors*A—

RS-485 Noninverting Receiver InputA20

RS-485 Inverting Receiver InputB19

RS-485 Noninverting Receiver Input and RS-485 Noninverting Driver Output*Y—

FULL

DUPLEX

HALF

DUPLEX

PIN

NAME FUNCTION