MAXIM MAX13485E, MAX13486E Technical data

General Description

The MAX13485E/MAX13486E +5V, half-duplex, ±15kV
ESD-protected RS-485 transceivers feature one driver
and one receiver. These devices include fail-safe circuitry,
guaranteeing a logic-high receiver output when receiver
inputs are open or shorted. The receiver outputs a logic­high if all transmitters on a terminated bus are disabled
(high impedance). The MAX13485E/MAX13486E include
a hot-swap capability to eliminate false transitions on the
bus during power-up or live-insertion.

The MAX13485E features reduced slew-rate drivers
that minimize EMI and reduce reflections caused by
improperly terminated cables, allowing error-free trans­mission up to 500kbps. The MAX13486E driver slew
rate is not limited, allowing transmit speeds up to
16Mbps.

The MAX13485E/MAX13486E feature a 1/4-unit load
receiver input impedance, allowing up to 128 transceivers
on the bus. These devices are intended for half-duplex
communications. All driver outputs are protected to ±15kV
ESD using the Human Body Model. The MAX13485E/
MAX13486E are available in 8-pin SO and space-saving
8-pin µDFN packages. The devices operate over the
extended -40°C to +85°C temperature range.

Applications

Utility Meters

Industrial Controls

Industrial Motor Drives

Automated HVAC Systems

Features

♦ +5V Operation

♦ True Fail-Safe Receiver While Maintaining

EIA/TIA-485 Compatibility

♦ Hot-Swappable for Telecom Applications

♦ Enhanced Slew-Rate Limiting Facilitates Error-

Free Data Transmission (MAX13485E)

♦ High-Speed Version (MAX13486E) Allows for

Transmission Speeds Up to 16Mbps

♦ Extended ESD Protection for RS-485/RS-422 I/O

Pins ±15kV Using Human Body Model

♦ 1/4 Unit Load, Allowing Up to 128 Transceivers on

the Bus

♦ Available in Space-Saving 8-Pin μDFN or Industry

Standard 8-Pin SO Packages

MAX13485E/MAX13486E

Half-Duplex RS-485/RS-422 Transceivers in µDFN

________________________________________________________________

Maxim Integrated Products

1

19-0742; Rev 0; 1/07

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.

Ordering Information/

Selector Guide

+

Denotes a lead-free package.
Note: All devices are specified over the -40°C to +85°C operating
temperature range.

Rt

RE

RO

B

A

A

B

Rt

R

D

RO

DI

8

7

6

5

1

2

3

4

RE

DE

R

DI

D

DE

+

123

87465

V

CC

A GNDB

RO DIDERE

MAX13485E
MAX13486E

DFN

+

A

GNDDI

1

2

87V

CC

BRE

DE

RO

SO

SO

3

4

6

5

R

D

+

TOP VIEW

GND

V

CC

0.1μF

MAX13485E
MAX13486E

Pin Configurations

PART

PIN­PACKAGE

MAX13485EELA+T 8 µDFN Yes L822-1

MAX13485EESA+ 8 SO Yes S8-2

MAX13486EELA+T 8 µDFN No L822-1

MAX13486EESA+ 8 SO No S8-2

SLEW-RATE

LIMITED

PKG

CODE

MAX13485E/MAX13486E

Half-Duplex RS-485/RS-422 Transceivers in µDFN

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

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.

(All voltages referenced to GND.)
V

CC

........................................................................................+6V

DE, RE, DI.................................................................-0.3V to +6V

A, B ..............................................................................-8V to 13V

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

Continuous Power Dissipation (T

A

= +70°C)

8-Pin SO (derate 5.9mW/°C above +70°C)..................471mW

8-Pin µDFN (derate 4.8mW/°C above +70°C) ..........380.6mW

Operating Temperature Range ...........................-40°C to +85°C

Junction Temperature......................................................+150°C

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

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

ELECTRICAL CHARACTERISTICS

(VCC= +5V ±5%, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at VCC= +5V and TA= +25°C.) (Notes 1, 2)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

DRIVER

Change in Magnitude of
Differential Output Voltage

Driver Common-Mode Output
Voltage

Change in Magnitude of
Common-Mode Voltage

Input-High Voltage V

Input-Low Voltage V

Input Current I

Driver Short-Circuit Output
Current (Note 4)

Driver Short-Circuit Foldback
Output Current Note 3)

RECEIVER

Input Current (A and B) I

Receiver-Differential-Threshold
Voltage

Receiver Input Hysteresis ΔV

Output-High Voltage V

R

= 100Ω, Figure 1 2.0 V

DIFF

R

= 54Ω, Figure 1 1.5Differential Driver Output V

OD

DIFF

No load V

R

ΔV

V

OC

ΔV

IN

I

OSD

I

OSDF

A, B

V

TH

OH

OD

OC

IH

IL

TH

= 100Ω or 54Ω, Figure 1 (Note 3) 0.2 V

DIFF

R

= 100Ω or 54Ω, Figure 1

DIFF

R

= 100Ω or 54Ω, Figure 1 (Note 3) 0.2 V

DIFF

DI, DE, RE 2.0 V
DI, DE, RE 0.8 V
DI, DE, RE ±1 µA

0V < V

-7V < V

< +12V +50 +250

OUT

OUT

(VCC - 1V) < V

-7V < V

OUT

DE = GND, VCC = GND
or +5V

-7V < VCM < +12V -200 -50 mV

VA + VB = 0V 25 mV

IO = -1.6mA, VA - VB > V

CC

CC

V

CC

/ 2

3V

< 0V -250 -50

< +12V 20

OUT

< 0V -20

VIN = +12V 250

= -7V -200

V

IN

V

-

TH

CC

1.5

V

mA

mA

µA

V

MAX13485E/MAX13486E

Half-Duplex RS-485/RS-422 Transceivers in µDFN

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VCC= +5V ±5%, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at VCC= +5V and TA= +25°C.) (Notes 1, 2)

SWITCHING CHARACTERISTICS—MAX13485E

(VCC= +5V ±5%, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at VCC= +5V and TA= +25°C.) (Note 1)

)

)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Output-Low Voltage V

Tri-State Output Current at
Receiver

Receiver Input Resistance R

Receiver-Output Short-Circuit
Current

POWER SUPPLY

Supply Voltage V

Supply Current I

Shutdown Supply Current I

ESD PROTECTION

ESD Protection (A, B)

ESD Protection (All Other Pins) Human Body Model ±2 kV

IO = 1mA, VA - VB < -V

OL

I

OZR

IN

I

OSR

CC

CC

SHDN

0V < VO < V

CC

-7V < VCM < +12V 48 kΩ

0V < V

RO

< V

CC

DE = 1, RE = 0, no load 4.5 mA
DE = 0, RE = 1 10 µA

TH

±7 ±95 mA

4.75 5.25 V

Air Gap Discharge IEC61000-4-2
(MAX13485E)

Human Body Model ±15

0.4 V

±1 µA

±15

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

DRIVER

Driver Propagation Delay

Driver-Differential Output Rise or
Fall Time

Driver-Differential Output Skew

- t

|t

DPLH

DPHL

|

Maximum Data Rate 500 kbps

Driver Enable to Output High t

Driver Enable to Output Low t

Driver Disable Time from High t

Driver Disable Time from Low t

Driver Enable from Shutdown to
Output High

Driver Enable from Shutdown to
Output Low

Time to Shutdown t

RECEIVER

Receiver Propagation Delay

Receiver Output Skew t

Maximum Data Rate 500 kbps

t

DPLH

t

DPHL

t

HL

t

LH

t

DSKEWRDIFF

DZH

DZL

DHZ

DLZ

t

DZH(SHDN

t

DZL(SHDN

SHDN

t

RPLH

t

RPHL

RSKEW

R

= 54Ω, CL = 50pF, Figures 2 and 3

DIFF

R

= 54Ω, CL = 50pF, Figures 2 and 3

DIFF

= 54Ω, CL = 50pF, Figures 2 and 3 140 ns

Figures 4 and 5 2500 ns

Figures 4 and 5 2500 ns

Figures 4 and 5 100 ns

Figures 4 and 5 100 ns

Figures 4 and 5 5500 ns

Figures 4 and 5 5500 ns

CL = 15pF, Figures 6 and 7

CL = 15pF, Figure 7 13 ns

200 1000

200 1000

250 900

250 900

50 340 700 ns

80

80

kV

ns

ns

ns

MAX13485E/MAX13486E

Half-Duplex RS-485/RS-422 Transceivers in µDFN

4 _______________________________________________________________________________________

SWITCHING CHARACTERISTICS—MAX13485E (continued)

(VCC= +5V ±5%, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at VCC= +5V and TA= +25°C.) (Note 1)

)

)

SWITCHING CHARACTERISTICS—MAX13486E

(VCC= +5V ±5%, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at VCC= +5V and TA= +25°C.) (Note 1)

)

)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Receiver Enable to Output High t

Receiver Enable to Output Low t

Receiver Disable Time from High t

Receiver Disable Time from Low t

Receiver Enable from Shutdown
to Output High

Receiver Enable from Shutdown
to Output Low

Time to Shutdown t

DRIVER

Driver Propagation Delay

Driver Differential Output Rise or
Fall Time

Differential Driver Output Skew
|t

DPLH

Maximum Data Rate 16 Mbps

Driver Enable to Output High t

Driver Enable to Output Low t

Driver Disable Time from High t

Driver Disable Time from Low t

Driver Enable from Shutdown to
Output High

Driver Enable from Shutdown to
Output Low

Time to Shutdown t

RECEIVER

Receiver Propagation Delay

Receiver Output Skew t

Maximum Data Rate 16 Mbps

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

- t

|

DPHL

RZH

RZL

RHZ

RLZ

t

RZH(SHDN

t

RZL(SHDN

SHDN

t

DPLH

t

DPHL

t

HL

t

LH

t

DSKEWRDIFF

DZH

DZL

DHZ

DLZ

t

DZH(SHDN

t

DZL(SHDN

SHDN

t

RPLH

t

RPHL

RSKEW

Figure 8 50 ns

Figure 8 50 ns

Figure 8 50 ns

Figure 8 50 ns

Figure 8 2200 ns

Figure 8 2200 ns

50 340 700 ns

R

= 54Ω, CL = 50pF, Figures 2 and 3

DIFF

R

= 54Ω, CL = 50pF, Figures 2 and 3

DIFF

= 54Ω, CL = 50pF, Figures 2 and 3 8 ns

Figures 4 and 5 50 ns

Figures 4 and 5 50 ns

Figures 4 and 5 50 ns

Figures 4 and 5 50 ns

Figures 4 and 5 2200 ns

Figures 4 and 5 2200 ns

50 340 700 ns

CL = 15pF, Figures 6 and 7

CL = 15pF, Figure 7 13 ns

50

50

15

15

80

80

ns

ns

ns

MAX13485E/MAX13486E

Half-Duplex RS-485/RS-422 Transceivers in µDFN

_______________________________________________________________________________________ 5

SWITCHING CHARACTERISTICS—MAX13486E (continued)

(VCC= +5V ±5%, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at VCC= +5V and TA= +25°C.) (Note 1)

)

)

Note 1: µDFN devices production tested at +25°C. Overtemperature limits are generated by design.
Note 2: All currents into the device are positive. All currents out of the device are negative. All voltages referred to device ground,

unless otherwise noted.

Note 3: ΔV

OD

and ΔVOCare the changes in VODand VOCwhen the DI input changes states.

Note 4: The short-circuit output current applied to peak current just prior to foldback current limiting. The short-circuit foldback

output current applies during current limiting to allow a recovery from bus contention.

Typical Operating Characteristics

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

3.0

3.2

3.6

3.4

3.8

4.0

-40 10-15 35 60 85

SUPPLY CURRENT vs. TEMPERATURE

MAX13485-86E toc01

TEMPERATURE (°C)

SUPPLY CURRENT (mA)

NO LOAD

0

7

21

14

28

35

021345

OUTPUT CURRENT vs. RECEIVER

OUTPUT HIGH VOLTAGE

MAX13485-86E toc02

OUTPUT HIGH VOLTAGE (V)

OUTPUT CURRENT (mA)

0

20

10

40

30

50

60

021345

OUTPUT CURRENT vs. RECEIVER

OUTPUT LOW VOLTAGE

MAX13485-86E toc03

OUTPUT LOW VOLTAGE (V)

OUTPUT CURRENT (mA)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Receiver Enable to Output High t

Receiver Enable to Output Low t

Receiver Disable Time from High t

Receiver Disable Time from Low t

Receiver Enable from Shutdown
to Output High

Receiver Enable from Shutdown
to Output Low

Time to Shutdown t

RZH

RZL

RHZ

RLZ

t

RZH(SHDN

t

RZL(SHDN

SHDN

Figure 8 50 ns

Figure 8 50 ns

Figure 8 50 ns

Figure 8 50 ns

Figure 8 2200 ns

Figure 8 2200 ns

50 340 700 ns

MAX13485E/MAX13486E

Half-Duplex RS-485/RS-422 Transceivers in µDFN

6 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

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

4.0

4.4

4.2

4.8

4.6

5.2

5.0

5.4

-40 10-15 35 60 85

RECEIVER OUTPUT HIGH

VOLTAGE vs. TEMPERATURE

MAX13485-86E toc04

TEMPERATURE (°C)

OUTPUT HIGH VOLTAGE (V)

IO = 1mA

0

0.1

0.3

0.2

0.4

0.5

-40 10-15 35 60 85

RECEIVER OUTPUT LOW

VOLTAGE vs. TEMPERATURE

MAX13485-86E toc05

TEMPERATURE (°C)

OUTPUT LOW VOLTAGE (V)

IO = 1mA

DIFFERENTIAL OUPUT CURRENT

vs. DIFFERENTIAL OUTPUT VOLTAGE

MAX13485-86E toc06

OUTPUT VOLTAGE (V)

OUTPUT CURRENT (mA)

4321

20

40

60

80

0

05

0

1.0

0.5

2.0

1.5

2.5

3.0

-40 10-15 35 60 85

DRIVER-DIFFERENTIAL OUTPUT

VOLTAGE vs. TEMPERATURE

MAX13485-86E toc07

TEMPERATURE (°C)

DIFFERENTIAL OUTPUT VOLTAGE (V)

R

DIFF

= 54Ω

0

40

20

80

60

100

120

-7 -5 -4 -3-6 -2 0-1 12345

OUTPUT CURRENT vs. TRANSMITTER

OUTPUT HIGH VOLTAGE

MAX13485-86E toc08

OUTPUT HIGH VOLTAGE (V)

OUTPUT CURRENT (mA)

0

40

20

80

60

100

120

0462 8 10 12

OUTPUT CURRENT vs. TRANSMITTER

OUTPUT LOW VOLTAGE

MAX13485-86E toc09

OUTPUT LOW VOLTAGE (V)

OUTPUT CURRENT (mA)

0

3

2

1

4

5

6

7

8

9

10

-40 10-15 35 60 85

SHUTDOWN CURRENT

vs. TEMPERATURE

MAX13485-86E toc10

TEMPERATURE (°C)

SHUTDOWN CURRENT (μA)

300

400

350

500

450

550

600

-40 10-15 35 60 85

DRIVER PROPAGATION

vs. TEMPERATURE (MAX13485E)

MAX13485-86E toc11

TEMPERATURE (°C)

DRIVER PROPAGATION DELAY (ns)

t

DPLH

t

DPHL

0

10

5

20

15

25

30

-40 10-15 35 60 85

DRIVER PROPAGATION DELAY

vs. TEMPERATURE (MAX13486E)

MAX13485-86E toc12

TEMPERATURE (°C)

DRIVER PROPAGATION DELAY (ns)

t

DPLH

t

DPHL

MAX13485E/MAX13486E

Half-Duplex RS-485/RS-422 Transceivers in µDFN

_______________________________________________________________________________________

7

Typical Operating Characteristics (continued)

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

RECEIVER PROPAGATION

vs. TEMPERATURE (MAX13485E)

80

60

40

PROPAGATION DELAY (ns)

20

0

-40 85

t

RPHL

t

RPLH

TEMPERATURE (°C)

603510-15

MAX13485-86E toc13

RECEIVER PROPAGATION (ns)

DRIVER PROPAGATION (16Mbps)

(MAX13486E)

MAX13485/86E toc16

RECEIVER PROPAGATION

vs. TEMPERATURE (MAX13486E)

40

30

t

RPLH

20

10

0

-40 85

t

RPHL

TEMPERATURE (°C)

603510-15

RECEIVER PROPAGATION (16Mbps)

DI
2V/div

MAX13485-86E toc14

DRIVER PROPAGATION (500kbps)

(MAX13485E)

400ns/div

(MAX13486E)

MAX13485/86E toc17

B
2V/div

MAX13485/86E toc15

DI
2V/div

A-B
5V/div

10ns/div

A-B
5V/div

10ns/div

A
2V/div

RO
2V/div

MAX13485E/MAX13486E

Half-Duplex RS-485/RS-422 Transceivers in µDFN

8 _______________________________________________________________________________________

Figure 1. Driver DC Test Load

Figure 2. Driver Timing Test Circuit

Figure 3. Driver Propagation Delays

Test Circuits and Waveforms

A

R

DIFF

2

V

OD

B

C

L

R

DIFF

2

V

OC

V

CC

DI

0

B

A

1/2 V

V

O

V

O

V

0

DIFF

-V

O

10%

LH

1.5V

O

f = 1MHz, tLH ≤ 3ns, tHL ≤ 3ns

t

DPLH

90%

t

DSKEW

5V

DE

A

DI

B

1.5V

t

DPHL

V

= V(A) - V(B)

DIFF

90%

t

HLt

= |t

- t

DPHL

|

DPLH

V

ID

10%

1/2 V

R

DIFF

O

C

L

MAX13485E/MAX13486E

Half-Duplex RS-485/RS-422 Transceivers in µDFN

_______________________________________________________________________________________ 9

Figure 4. Driver Enable and Disable Times

Figure 6. Receiver Propagation Delay Test Circuit

Figure 5. Driver-Enable and -Disable-Timing Test Load

Figure 7. Receiver Propagation Delays

Test Circuits and Waveforms (continued)

V

CC

DE

0

A, B

V

OL

A, B

0

OUTPUT

UNDER TEST

500Ω

C

L

1.5V

t

DZL(SHDN),tDZL

2.3V

2.3V

V

S1

CC

OUTPUT NORMALLY LOW

OUTPUT NORMALLY HIGH

t

DZH(SHDN),tDZH

ATE

t

t

DHZ

DLZ

1.5V

V

+ 0.5V

OL

+ 0.5V

V

OH

B

V

ID

R

A

RECEIVER
OUTPUT

S2

A

B

V

OH

RO

V

OL

1.5V

f = 1MHz, t

t

RPHL

≤ 3ns, tHL ≤ 3ns

LH

t

RPLH

1.5V

= |t

- t

RPHL

RPLH

|

t

RSKEW

1V

-1V

MAX13485E/MAX13486E

Half-Duplex RS-485/RS-422 Transceivers in µDFN

10 ______________________________________________________________________

Pin Description

Function Tables

X = Don’t care, shutdown mode, driver, and receiver outputs
are in high impedance.

PIN NAME FUNCTION

1 RO Receiver Output

Receiver Output Enable. Drive RE low to enable RO. RO is high impedance when RE is high. Drive

2 RE

3DE

RE high and DE low to enter low-power shutdown mode. RE is a hot-swap input (see the Hot-Swap
Capability section for more details).

Driver Output Enable. Drive DE high to enable the driver outputs. These outputs are high-impedance
when DE is low. Drive RE high and DE low to enter low-power shutdown mode. DE is a hot-swap input
(see the Hot-Swap Capability section for more details).

4DI

5 GND Ground

6 A Noninverting Receiver Input and Noninverting Driver Output

7 B Inverting Receiver Input and Inverting Driver Output

8VCCPositive Supply, VCC = +5V ±5%. Bypass VCC to GND with a 0.1µF capacitor.

Driver Input. Drive DI low to force noninverting output low and inverting output high. Drive DI high to
force noninverting output high and inverting output low (see the Function Tables).

TRANSMITTING

INPUT OUTPUT

RE DE DI B A

X11 0 1

X10 1 0

0 0 X HIGH IMPEDANCE HIGH IMPEDANCE

1 0 X SHUTDOWN

RECEIVING

INPUT OUTPUT

RE DE A-B RO

0X > -50mV 1

0X < -200mV 0

0 X OPEN/SHORT 1

1 1 X HIGH IMPEDANCE

1 0 X SHUTDOWN

MAX13485E/MAX13486E

Half-Duplex RS-485/RS-422 Transceivers in µDFN

__________________________________________________________________________

Figure 8. Receiver Enable and Disable Times

Test Circuits and Waveforms (continued)

+1V

-1V

S1 OPEN
S2 CLOSED
S3 = +1V

RE

RO

S3

GENERATOR

t

RZH

V

CC

, t

RZH(SHDN)

1kΩ

CL
15pF

RE

RO

V

ID

50Ω

V

CC

/2

0

V

OH

V

/2

OH

0

S1

S2

S1 CLOSED
S2 OPEN
S3 = -1V

V

CC

V

CC

VCC/2

0

t

, t

RZL

RZL(SHDN)

V

CC

(VOL + VCC)/2

V

OL

S1 OPEN
S2 CLOSED
S3 = +1V

VCC/2

RE

t

RHZ

RO

0.25V

S1 CLOSED
S2 OPEN

VCC/2

S3 = -1V

t

RLZ

0.25V

V

CC

0

V

OH

0

RE

RO

V

CC

0

V

CC

V

OL

MAX13485E/MAX13486E

Detailed Description

The MAX13485E/MAX13486E half-duplex, high-speed
transceivers for RS-485/RS-422 communication contain
one driver and one receiver. These devices feature fail­safe circuitry that guarantees a logic-high receiver out­put when receiver inputs are open or shorted, or when
they are connected to a terminated transmission line
with all drivers disabled (see the

Fail-Safe

section). The
MAX13485E/MAX13486E also feature a hot-swap capa­bility allowing line insertion without erroneous data
transfer (see the

Hot-Swap Capability

section). The
MAX13485E features reduced slew-rate drivers that
minimize EMI and reduce reflections caused by
improperly terminated cables, allowing error-free trans­mission up to 500kbps. The MAX13486E driver slew
rate is not limited, making transmit speeds up to
16Mbps possible.

Fail-Safe

The MAX13485E/MAX13486E 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 all drivers disabled. This is done by
setting the receiver input threshold between -50mV and

-200mV. If the differential receiver input voltage (A - B) is
greater than or equal to -50mV, RO is logic-high. If (A - B)
is less than or equal to -200mV, RO is logic-low. In the
case of a terminated bus with all transmitters disabled,
the receiver’s differential input voltage is pulled to 0V by
the termination. With the receiver thresholds of the
MAX13485E/MAX13486E, this results is a logic-high with
a 50mV minimum noise margin. Unlike previous fail-safe
devices, the -50mV to -200mV threshold complies with
the ±200mV EIA/TIA-485 standard.

Hot-Swap Capability

Hot-Swap Inputs

When circuit boards are inserted into a hot or powered
backplane, differential disturbances to the data bus
can lead to data errors. Upon initial circuit-board inser­tion, the data communication processor undergoes its
own power-up sequence. During this period, the
processor’s logic-output drivers are high impedance
and are unable to drive the DE and RE inputs of these
devices to a defined logic level. Leakage currents up to
±10µA from the high impedance state of the proces­sor’s logic drivers could cause standard CMOS enable
inputs of a transceiver to drift to an incorrect logic level.
Additionally, parasitic circuit-board capacitance could
cause coupling of VCCor GND to the enable inputs.
Without the hot-swap capability, these factors could
improperly enable the transceiver’s driver or receiver.

When V

CC

rises, an internal pulldown circuit holds DE

low and RE high. After the initial power-up sequence,
the pulldown circuit becomes transparent, resetting the
hot-swap tolerable input.

Hot-Swap Input Circuitry

The enable inputs feature hot-swap capability. At the
input there are two nMOS devices, M1 and M2 (Figure

9). When VCCramps from zero, an internal 7µs timer
turns on M2 and sets the SR latch, which also turns on
M1. Transistors M2, a 1.5mA current sink, and M1, a
500µA current sink, pull DE to GND through a 5kΩ
resistor. M2 is designed to pull DE to the disabled state
against an external parasitic capacitance up to 100pF
that can drive DE high. After 7µs, the timer deactivates
M2 while M1 remains on, holding DE low against tri­state leakages that can drive DE high. M1 remains on
until an external source overcomes the required input
current. At this time, the SR latch resets and M1 turns
off. When M1 turns off, DE reverts to a standard high­impedance CMOS input. Whenever V

CC

drops below

1V, the hot-swap input is reset.
For RE there is a complementary circuit employing two

pMOS devices pulling RE to VCC.

Half-Duplex RS-485/RS-422 Transceivers in µDFN

12 ______________________________________________________________________________________

Figure 9. Simplified Structure of the Driver Enable Pin (DE)

V

CC

10μs

TIMER

SR LATCH

TIMER

DE

5kΩ

100μA

500μA

M2M1

DE
(HOT SWAP)

+15V ESD Protection

As with all Maxim devices, ESD-protection structures
are incorporated on all pins to protect against electro­static discharges encountered during handling and
assembly. The driver outputs and receiver inputs of the
MAX13485E/MAX13486E have extra protection against
static electricity. Maxim’s engineers have developed
state-of-the-art structures to protect these pins against
ESD of ±15kV without damage. The ESD structures
withstand high ESD in all states: normal operation, shut­down, and powered down. After an ESD event, the
MAX13485E/MAX13486E keep working without latchup
or damage.

ESD protection can be tested in various ways. The trans­mitter outputs and receiver inputs of the MAX13485E/
MAX13486E are characterized for protection to the follow­ing limits:

• ±15kV using the Human Body Model

• ±15kV using the Air Gap Discharge Method specified
in IEC 61000-4-2 (MAX13485E only)

ESD Test Conditions

ESD performance depends on a variety of conditions.
Contact Maxim for a reliability report that documents
test setup, test methodology, and test results.

Human Body Model

Figure 10a shows the Human Body Model, and Figure
10b shows the current waveform it generates when dis­charged into a low impedance. This model consists of
a 100pF capacitor charged to the ESD voltage of inter­est, which is then discharged into the test device
through a 1.5kΩ resistor.

IEC 61000-4-2

The IEC 61000-4-2 standard covers ESD testing and
performance of finished equipment. However, it does
not specifically refer to integrated circuits. The
MAX13485E/MAX13486E help equipment designs to
meet IEC 61000-4-2, without the need for additional
ESD-protection components.

The major difference between tests done using the
Human Body Model and IEC 61000-4-2 is higher peak
current in IEC 61000-4-2 because series resistance is
lower in the IEC 61000-4-2 model. Hence, the ESD

MAX13485E/MAX13486E

Half-Duplex RS-485/RS-422 Transceivers in µDFN

______________________________________________________________________________________ 13

Figure 10a. Human Body ESD Test Model

Figure 10b. Human Body Current Waveform

Figure 10c. IEC 61000-4-2 ESD Test Model

Figure 10d. IEC 61000-4-2 ESD Generator Current Waveform

HIGH-

VOLTAGE

DC

SOURCE

R

C

1MΩ

CHARGE-CURRENT

LIMIT RESISTOR

C

100pF

s

R

D

1500Ω

DISCHARGE
RESISTANCE

STORAGE
CAPACITOR

AMPS

IP 100%

90%

36.8%

10%

0

0

t

RL

I

r

TIME

t

DL

CURRENT WAVEFORM

DEVICE
UNDER

PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)

TEST

HIGH-

VOLTAGE

DC

SOURCE

R

C

50MΩ TO 100MΩ

CHARGE-CURRENT

LIMIT RESISTOR

C

150pF

s

R

D

330Ω

DISCHARGE

RESISTANCE

STORAGE
CAPACITOR

I

100%

90%

PEAK

I

10%

tr = 0.7ns TO 1ns

30ns

60ns

DEVICE
UNDER

TEST

t

MAX13485E/MAX13486E

withstand voltage measured to IEC 61000-4-2 is gener­ally lower than that measured using the Human Body
Model. Figure 10c shows the IEC 61000-4-2 model,
and Figure 10d shows the current waveform for the IEC
61000-4-2 ESD Contact Discharge test.

Machine Model

The machine model for ESD tests all pins using a 200pF
storage capacitor and zero discharge resistance.

The objective is to emulate the stress caused when I/O
pins are contacted by handling equipment during test
and assembly. Of course, all pins require this protec­tion, not just RS-485 inputs and outputs.

The air-gap test involves approaching the device with a
charged probe. The contact-discharge method connects
the probe to the device before the probe is energized.

Applications Information

128 Transceivers on the Bus

The standard RS-485 receiver input impedance is 12kΩ
(1-unit load), and the standard driver can drive up to
32-unit loads. The MAX13485E/MAX13486E have a 1/4­unit load receiver input impedance (48kΩ), allowing up
to 128 transceivers to be connected in parallel on one
communication line. Any combination of these devices,
as well as other RS-485 transceivers with a total of 32­unit loads or fewer, can be connected to the line.

Reduced EMI and Reflections

The MAX13485E features reduced slew-rate drivers
that minimize EMI and reduce reflections caused by
improperly terminated cables, allowing error-free data
transmission up to 500kbps.

Low-Power Shutdown Mode

Low-power shutdown mode is initiated by bringing both
RE high and DE low. In shutdown, the devices draw a
maximum of 10µA of supply current.

RE and DE can be driven simultaneously. The devices
are guaranteed not to enter shutdown if RE is high and
DE is low for less than 50ns. If the inputs are in this
state for at least 700ns, the devices are guaranteed to
enter shutdown.

Enable times tZHand tZL(see the

Switching Character-

istics

) assume the devices were not in a low-power shut-

down state. Enable times t

ZH(SHDN)

and t

ZL(SHDN)

assume the devices were in shutdown state. It takes dri­vers and receivers longer to become enabled from low­power shutdown mode (t

ZH(SHDN)

, t

ZL(SHDN)

) than from

driver-/receiver-disable mode (tZH, tZL).

Line Length

The RS-485/RS-422 standard covers line lengths up to
4000ft.

Typical Applications

The MAX13485E/MAX13486E transceivers are
designed for half-duplex, bidirectional data communi­cations on multipoint bus transmission lines. Figure 11
shows typical network applications circuits. To mini­mize reflections, terminate the line at both ends in its
characteristic impedance, and keep stub lengths off
the main line as short as possible. The slew-rate-limited
MAX13485E is more tolerant of imperfect termination.

Chip Information

PROCESS: BiCMOS

Half-Duplex RS-485/RS-422 Transceivers in µDFN

14 ______________________________________________________________________________________

Figure 11. Typical Half-Duplex RS-485 Network

DI

DE

RO

RE

D

MAX13485E
MAX13486E

R

t

R

R

D

DE

DI RO RE DI RO RE

R

t

R

D

DE

D

R

DI

DE

RO
RE

MAX13485E/MAX13486E

Half-Duplex RS-485/RS-422 Transceivers in µDFN

______________________________________________________________________________________ 15

Package Information

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages

.)

N

1

TOP VIEW

D

e

FRONT VIEW

INCHES

DIM

MIN

0.053A

0.004

A1

0.014

B

0.007

C
e 0.050 BSC 1.27 BSC

0.150

HE

A

B

A1

C

L

E
H 0.2440.228 5.80 6.20

0.016L

VARIATIONS:

INCHES

MINDIM

D

0.189 0.197 AA5.004.80 8

0.337 0.344 AB8.758.55 14

D

0∞-8∞

SIDE VIEW

MAX

0.069

0.010

0.019

0.010

0.157

0.050

MAX

0.3940.386D

MILLIMETERS

MAX

MIN

1.35

1.75

0.10

0.25

0.35

0.49

0.19

0.25

3.80 4.00

0.40 1.27

MILLIMETERS

MAX

MIN

9.80 10.00

N MS012

16

AC

SOICN .EPS

PROPRIETARY INFORMATION

TITLE:

PACKAGE OUTLINE, .150" SOIC

REV.DOCUMENT CONTROL NO.APPROVAL

21-0041

1

B

1

Package Information (continued)

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages

.)

MAX13485E/MAX13486E

Half-Duplex RS-485/RS-422 Transceivers in µDFN

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.

16

____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

© 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.

Boblet

D

A

XXXX
XXXX

SAMPLE
MARKING

7

A1

E

b

A

XXXX

PIN 1
INDEX AREA

-DRAWING NOT TO SCALE-

COMMON DIMENSIONS

SYMBOL MIN. NOM.

A

0.70 0.75

0.15 0.20 0.25

A1

0.020 0.025 0.035

A2

D 1.95 2.00

E

1.95 2.00

L

0.30 0.40

L1

0.10 REF.

MAX.

0.80

2.05

-

2.05

0.50

e

L

C

L

L

A2

e

EVEN TERMINAL

b

A A

(N/2 -1) x e)

PACKAGE OUTLINE,
6, 8, 10L uDFN, 2x2x0.80 mm

21-0164

N

1

C
L

e

ODD TERMINAL

SOLDER
MASK
COVERAGE

PIN 1

0.10x45∞

L1

L

1

A

2

6, 8, 10L UDFN.EPS

PACKAGE VARIATIONS

PKG. CODE N e b

6L622-1 0.65 BSC 0.30±0.05

-DRAWING NOT TO SCALE-

(N/2 -1) x e

1.30 REF.

1.50 REF.

0.25±0.050.50 BSC8L822-1

1.60 REF.

0.20±0.030.40 BSC10L1022-1

PACKAGE OUTLINE,
6, 8, 10L uDFN, 2x2x0.80 mm

21-0164

2

A

2