MAXIM MAX14840E, MAX14841E Technical data

19-5131; Rev 0; 2/10

40Mbps, +3.3V, RS-485 Half-Duplex

Transceivers

General Description

The MAX14840E/MAX14841E are +3.3V ESD-protected
transceivers intended for half-duplex RS-485 communi­cation up to 40Mbps. These transceivers are optimized
for high speeds over extended cable runs while maximiz­ing tolerance to noise.

The MAX14840E features symmetrical fail-safe and larg­er receiver hysteresis, providing improved noise rejec­tion and improved recovered signals in high-speed and
long cable applications. The MAX14841E has true fail­safe receiver inputs guaranteeing a logic-high receiver
output when inputs are shorted or open.

The MAX14840E/MAX14841E transceivers draw 1.5mA
(typ) supply current when unloaded or when fully loaded
with the drivers disabled. Hot-swap capability eliminates
undesired transitions on the bus during power-up or hot
insertion.

The MAX14840E/MAX14841E are available in 8-pin SO
and small, 8-pin (3mm x 3mm) TDFN-EP packages. Both
devices operate over the -40NC to +125NC automotive
temperature range.

Applications

Motion Controllers

Fieldbus Networks

Industrial Control Systems

Backplane Buses

HVAC Networks

Ordering Information/Selector Guide

Features

S Half-Duplex RS-485 Transceivers

S +3.3V Supply Voltage

S 40Mbps Maximum Data Rate

S Large (170mV) Receiver Hysteresis on

MAX14840E

S Symmetrical Fail-Safe Receiver Input on

MAX14840E

S Fail-Safe Receiver Input (MAX14841E)

S Hot-Swap Capability

S Short-Circuit Protected Outputs

S Thermal Self-Protection

S Low 10µA (max) Shutdown Current

S Extended ESD Protection for RS-485 I/O Pins

±35kV Human Body Model (HBM)
±20kV Air-Gap Discharge per IEC 61000-4-2
±12kV Contact Discharge per IEC 61000-4-2

S Automotive -40°C to +125°C Operating

Temperature Range

S Available in Industry-Standard 8-Pin SO or

Space-Saving, 8-Pin TDFN-EP (3mm x 3mm)
Packages

MAX14840E/MAX14841E

PART FAIL SAFE TEMP RANGE PIN-PACKAGE

MAX14840EASA+ Symmetrical

MAX14840EATA+ Symmetrical

MAX14841EASA+ True

MAX14841EATA+ True

+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.

_______________________________________________________________ Maxim Integrated Products 1

-40NC to +125NC

-40NC to +125NC

-40NC to +125NC

-40NC to +125NC

8 SO

8 TDFN-EP*

8 SO

8 TDFN-EP*

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.

40Mbps, +3.3V, RS-485 Half-Duplex
Transceivers

ABSOLUTE MAXIMUM RATINGS

(Voltages referenced to GND.)

VCC ..................................................................... -0.3V to +6.0V

RE, RO .................................................. -0.3V to +(V

DE, DI .................................................................. -0.3V to +6.0V

A, B .................................................................... -8.0V to +13.0V

Short-Circuit Duration (RO, A, B) to GND ............... Continuous

Continuous Power Dissipation (TA = +70NC)

8-Pin SO (derate 7.6mW/NC above +70NC) ............... 606mW

8-Pin TDFN (derate 24.4mW/NC above +70NC) ....... 1951mW

Junction-to-Case Thermal Resistance (BJC) (Note 1)

8-Pin SO .......................................................................38NC/W

8-Pin TDFN ....................................................................8NC/W

Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-

layer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.

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.

CC

+ 0.3V)

DC ELECTRICAL CHARACTERISTICS

(VCC = +3.0V to +3.6V, TA = -40NC to +125NC, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25NC.) (Notes 2, 3)

MAX14840E/MAX14841E

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

POWER SUPPLY

Supply Voltage V

Supply Current I

Shutdown Supply Current I

DRIVER

Differential Driver Output V

Change in Magnitude of
Differential Output Voltage

Driver Common-Mode Output
Voltage

Change in Common-Mode
Voltage

Single-Ended Driver Output High V
Single-Ended Driver Output Low V

Driver Short-Circuit Output
Current

RECEIVER

Input Current (A and B) I

Differential Input Capacitance C

DV

V

DV

|I

OSD

CC

CC

SH

OD

OD

OC

OC

OH

OL

A,B

A,B

DE = RE = VCC, or
DE = RE = GND, or
DE = VCC, RE = GND,
DI = VCC or GND, no load

DE = GND and RE = V

RL = 54I, Figure 1

RL = 54I, Figure 1 (Note 4)

RL = 54I, Figure 1

RL = 54I, Figure 1 (Note 4)

A/B output, I
A/B output, I
0V P V

|

-7V P V

DE = GND,
VCC = GND or +3.6V

Between A and B, DE = GND, f = 2MHz 12 pF

P +12V, output low

OUT

P VCC, output high

OUT

Junction-to-Ambient Thermal Resistance (BJA) (Note 1)

8-Pin SO ....................................................................132NC/W

8-Pin TDFN ..................................................................41NC/W

Operating Temperature Range ...................... -40NC to +125NC

Junction Temperature .................................................. +150NC

Storage Temperature Range ......................... -65NC to +150NC

Lead Temperature (soldering, 10s) ...............................+300NC

Soldering Temperature (reflow) ......................................+260NC

3.0 3.6 V

1.5 4 mA

CC

1.5 V

-0.2 0 +0.2 V

VCC/2 3 V

-0.2 0.2 V

= -20mA 2.2 V

OUT

= 20mA 0.8 V

OUT

250

VIN = +12V 1000
VIN = -7V -800

10

250

FA

mA

FA

2 ______________________________________________________________________________________

40Mbps, +3.3V, RS-485 Half-Duplex

Transceivers

DC ELECTRICAL CHARACTERISTICS (continued)

(VCC = +3.0V to +3.6V, TA = -40NC to +125NC, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25NC.) (Notes 2, 3)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Receiver Differential Threshold
Voltage (MAX14840E Only)

Receiver Input Hysteresis
(MAX14840E Only)

Receiver Differential Threshold
Voltage (MAX14841E Only)

Receiver Input Hysteresis
(MAX14841E Only)

LOGIC INTERFACE

Input High Voltage V

Input Low Voltage V
Input Hysteresis V
Input Current I

Input Impedance on First
Transition

Output High Voltage V

Output Low Voltage V

Three-State Output Current at
Receiver

Receiver Output Short-Circuit
Current

PROTECTION

Thermal Shutdown Threshold T
Thermal Shutdown Hysteresis T

ESD Protection: A, B to GND

ESD Protection: All Other Pins HBM

V
V

V

DV

I

OZR

I

OSR

THF

THR

TH

HYS

IN

OH

OL

TS

TSH

-7V P VCM P 12V, V

-7V P VCM P 12V, V

VCM = 0V 20 170 mV

-7V P VCM P 12V

VCM = 0V 10 mV

TH

DE, DI 2.0 5.5

IH

RE

DE, DI, RE

IL

DE, DI, RE
DE, DI, RE

DE, RE

RE = GND, IO = -1mA, VA - VB > 200mV

RE = GND, IO = 1mA, VA - VB < -200mV

RE = VCC, 0V P VO P V

0V P VRO P V

IEC 61000-4-2 Air Gap Discharge

HBM

CC

OD

OD

falling
rising

CC

-200 -10 mV
10 200 mV

-200 -105 -10 mV

2.0

0.8 V

50 mV

-1 +1

1 10

VCC -

1.5

0.4 V

-1 +1

-95 +95 mA

160

15

Q20
Q12
Q35

Q2

V

FA

kI

V

FA

NC
NC

kVIEC 61000-4-2 Contact Discharge

kV

MAX14840E/MAX14841E

SWITCHING CHARACTERISTICS

(VCC = +3.0V to +3.6V, TA = -40NC to +125NC, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25NC.) (Notes 2, 3)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

DRIVER

Propagation Delay

Differential Driver Output Skew
|t

- t

DPHL

|

_______________________________________________________________________________________ 3

DPLH

Driver Differential Output Rise or
Fall Time

t

DPLH

t

DPHL

t

DSKEW

tHL, t

RL = 54I, CL = 50pF, Figures 2 and 3
(Note 5)

RL = 54I, CL = 50pF, Figures 2 and 3
(Notes 5, 8)

RL = 54I, CL = 50pF, Figures 2 and 3

LH

(Notes 5, 8)

5 12 20
5 12 20

7.5 ns

ns

2 ns

40Mbps, +3.3V, RS-485 Half-Duplex
Transceivers

SWITCHING CHARACTERISTICS (continued)

(VCC = +3.0V to +3.6V, TA = -40NC to +125NC, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25NC.) (Notes 2, 3)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Maximum Data Rate DR

Driver Enable to Output High t

Driver Enable to Output Low t

Driver Disable Time from Low t

Driver Disable Time from High t

Driver Enable from Shutdown to
Output Low

Driver Enable from Shutdown to
Output High

Time to Shutdown t

RECEIVER

Propagation Delay

MAX14840E/MAX14841E

Receiver Output Skew t
Maximum Data Rate DR
Receiver Enable to Output High t
Receiver Enable to Output Low t
Receiver Disable Time from Low t
Receiver Disable Time from High t

Receiver Enable from Shutdown
to Output Low

Receiver Enable from Shutdown
to Output High

Time to Shutdown t

Note 2: All devices are 100% production tested at TA = +25NC. Specifications for all temperature limits are guaranteed by design.
Note 3: All currents into the device are positive; all currents out of the device are negative. All voltages are referenced to device

ground, unless otherwise noted.

Note 4: DV OD and DVOC are the changes in VOD and VOC, respectively, when the DI input changes state.
Note 5: Capacitive load includes test probe and fixture capacitance.
Note 6: The timing parameter refers to the driver or receiver enable delay when the device has exited the initial hot-swap protect

state and is in normal operating mode.

Note 7: Shutdown is enabled by driving RE high and DE low. The device is guaranteed to have entered shutdown after t

elapsed.

Note 8: Parameter is guaranteed by characterization and not production tested.

MAX

DZH

DZL

DLZ

DHZ

t

DZL(SHDN)

t

DZH(SHDN)

SHDN

t

RPLH

t

RPHL

RSKEW

MAX

RZH

RZL

RLZ

RHZ

t

RZL(SHDN)

t

RZH(SHDN)

SHDN

RL = 110I, CL = 50pF, Figures 4 and 5
(Notes 5, 6)

RL = 110I, CL = 50pF, Figures 4 and 5
(Notes 5, 6)

RL = 110I, CL = 50pF, Figures 4 and 5
(Notes 5, 6)

RL = 110I, CL = 50pF, Figures 4 and 5
(Notes 5, 6)

RL = 110I, CL = 50pF, Figures 4 and 5
(Notes 5, 6)

RL = 110I, CL = 50pF, Figures 4 and 5
(Notes 5, 6)

(Note 7) 50 800 ns

CL = 15pF, Figures 6 and 7 (Note 5)

CL = 15pF, Figures 6 and 7 (Notes 5, 8) 2 ns

RL = 1kI, CL = 15pF, Figure 8 (Notes 5, 6)
RL = 1kI, CL = 15pF, Figure 8 (Notes 5, 6)
RL = 1kI, CL = 15pF, Figure 8 (Notes 5, 6)
RL = 1kI, CL = 15pF, Figure 8 (Notes 5, 6)

RL = 1kI, CL = 15pF, Figure 8 (Notes 5, 6)

RL = 1kI, CL = 15pF, Figure 8 (Notes 5, 6)

(Note 7) 50 800 ns

40 Mbps

30 ns

30 ns

30 ns

30 ns

4

4

25
25

40 Mbps

20 ns
20 ns
20 ns
20 ns

4

4

SHDN

Fs

Fs

ns

Fs

Fs

has

4 ______________________________________________________________________________________

40Mbps, +3.3V, RS-485 Half-Duplex

Transceivers

Test and Timing Diagrams

MAX14840E/MAX14841E

A

R

L

2

V

OD

R

L

V

OC

2

B

V

CC

DE

DI

A

B

V

OD

Figure 1. Driver DC Test Load Figure 2. Driver Timing Test Circuit

t

LH

f = 1MHz, tLH = 3ns, t

90%

V

CC

1.5V 1.5V

0

t

DPLH

B

A

V

V

O

V

0

OD

-V

O

OD

10%

= 3ns

HL

VOD = [VA - VB]

90%

t

DPHL

t

HL

10%

R

L

C

L

Figure 3. Driver Propagation Delays

A

GND OR V

GENERATOR

DI

CC

D

DE

50I

S1

C

50pF

L

B

Figure 4. Driver Enable and Disable Times (t

_______________________________________________________________________________________ 5

DZH

t

DSKEW = tDPLH

OUT

R

110I

L =

, t

)

DHZ

DE

OUT

- t



DPHL

V

CC

t

DZH

, t

DZH(SHDN)

1.5V

1.5V

0.25V

t

DHZ

0

V

OH

0