Datasheet MAX13415E Datasheet (MAXIM)

General Description

The MAX13410E–MAX13415E are half-duplex RS-485-/RS422-compatible transceivers optimized for isolated applications. These devices feature an internal low-dropout regulator (LDO), one driver, and one receiver. The internal LDO allows the part to operate from an unregulated power supply of up to 28V. The AutoDirection feature reduces the number of optical isolators needed in isolated applications. Other features include enhanced ESD protection, fail-safe circuitry, slew-rate limiting, and fullspeed operation.

The MAX13410E–MAX13415E internal LDO generates a 5V ±10% power supply that is used to power its internal circuitry. The MAX13412E–MAX13415E bring the 5V to an output V

REG

that allows the user to power additional external circuitry with up to 20mA to further reduce external components. The MAX13410E/MAX13411E do not have a 5V output and come in industry-compatible pinouts. This allows easy replacement in existing designs.

The MAX13410E–MAX13415E feature a 1/8-unit load receiver input impedance, allowing up to 256 transceivers on the bus. All driver outputs are ESD protected using the Human Body Model. These devices also include fail-safe circuitry (MAX13410E/MAX13411E/ MAX13414E/MAX13415E only), guaranteeing a logichigh receiver output when the receiver inputs are open or shorted. The receiver outputs a logic-high when the transmitter on the terminated bus is disabled (high impedance).

The MAX13412E/MAX13413E feature Maxim’s proprietary AutoDirection control. This architecture eliminates the need for the DE and RE control signals. In isolated applications, this reduces the cost and size of the system by reducing the number of optical isolators required.

The MAX13410E/MAX13412E/MAX13414E feature reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, allowing error-free transmission up to 500kbps. The MAX13411E/MAX13413E/MAX13415E are not slew-rate limited, allowing transmit speeds up to 16Mbps.

The MAX13410E–MAX13415E are available in an 8-pin SO package with an exposed paddle to improve power dissipation, and operate over the extended -40°C to +85°C temperature range.

Features

♦ Wide +6V to +28V Input Supply Range

♦ +5V Output Supplies Up to 20mA to External

Circuitry

♦ Internal LDO

♦ Low 65µA (typ) Shutdown Supply Current

♦ Extended ESD Protection

±15kV Human Body Model (MAX13412E/ MAX13413E) ±14kV Human Body Model (MAX13410E/ MAX13411E)

♦ 1/8-Unit Load, Allowing Up to 256 Transceivers on

the Bus

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

♦ Fail-Safe

♦ Slew-Rate Limited and Full-Speed Versions

♦ Up to 16Mbps Data Rate on Full-Speed Versions

Applications

-

MAX13410E–MAX13415E

RS-485 Transceiver with Integrated Low-Dropout

Regulator and AutoDirection Control

________________________________________________________________

Maxim Integrated Products

1

19-1058; Rev 1; 8/09

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.

Ordering Information/Selector Guide

Note: All devices operate over the -40°C to +85°C operating temperature range.

+

Denotes a lead(Pb)-free/RoHS-compliant package.

*

EP = Exposed pad.

Ordering Information/Selector Guide continued at end of data sheet.

Isolated RS-485 Interfaces

Utility Meters

Industrial Equipment

Telecomm Equipment

Pin Configurations

Pin Configurations continued at end of data sheet.

TOP VIEW

1

RO

+

87V

CC

2

MAX13410E

3

DE

4

MAX13411E

*EP

BRE

A

6

GNDDI

5

*EXPOSED PAD CONNECTED TO GROUND

SO

PART PIN-PACKAGE AutoDirection DATA RATE (max) 5V LDO OUTPUT

MAX13410EESA+ 8 SO-EP* No 500 kbps No

MAX13411EESA+ 8 SO-EP* No 16Mbps No

MAX13410E–MAX13415E

RS-485 Transceiver with Integrated Low-Dropout Regulator and AutoDirection Control

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

.........................................................................-0.3V to +30V

RE, DE/RE, DE, DI, RO, V

REG

..................................-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-EP (derate 19.2mW/°C above +70°C) ........1539mW

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

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

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

θ

JA

(Note 1)...................................................................52.0°C/W

θ

JC

(Note 1).....................................................................6.0°C/W

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

Note 1: Package thermal resistances were obtained using the method described in JEDEC specificactions JESD51-7 using a four layer board.

For detailed information on package consitencies refer to www.maxim-ic/thermal-tutorial.

ELECTRICAL CHARACTERISTICS

(VCC= +6.0V to +28V, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at VCC= +7.5V, CS= 1µF, and TA= +25°C.) (Note 2)

Supply Voltage V

LDO Output Voltage V

LDO Output Current I

LDO Dropout Voltage V

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Minimum Bypass Capacitor on V

Supply Current I

Shutdown Current I

Thermal-Shutdown Threshold T

Thermal-Shutdown Threshold Hysteresis

DRIVER

Change in Magnitude of Differential Output Voltage

Driver Common-Mode Output Voltage V

Change In Magnitude of CommonMode Voltage

Input High Voltage V

Input Low Voltage V

Input Current I

Driver-Disable Threshold V

(Note 3) 6.0 28.0 V

CC

VCC = +7.5V, I

VCC = +28V, I

VCC > +7.5V 20

VCC = +5V, I

DO

Guaranteed by design,

S

MAX13412E–MAX13415E

RE, DE = high/no load (MAX13410E/MAX13411E)

CC

RE, DE/RE = high, DI = low/no load (MAX13412E–MAX13415E)

DE = low, RE = high (MAX13410E/MAX13411E)

TS

R

= 100Ω, Figure 1 2.0 5.5

DIFF

R

= 54Ω, Figure 1 1.5 5.5Differential Driver Output V

OD

OC

IH

IL

IN

DT

DIFF

No load 5.5

R

= 100Ω or 54Ω, Figure 1 0.2 V

DIFF

R

= 100Ω or 54Ω, Figure 1 1 3 V

DIFF

R

= 100Ω or 54Ω, Figure 1 0.2 V

DIFF

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

TA = +25°C (MAX13412E/MAX13413E) 0.6 1.0 V

REG

C

SHDN

T

TSH

ΔV

= 20mA 4.5 5 5.5

LOAD

= 0mA 4.5 5 5.5

LOAD

= 20mA 0.5 V

OUT

1µF

10

45 µA

+150 °C

15 °C

V

mA

V

MAX13410E–MAX13415E

RS-485 Transceiver with Integrated Low-Dropout

Regulator and AutoDirection Control

_______________________________________________________________________________________ 3

SWITCHING CHARACTERISTICS–MAX13410E

(VCC= +6.0V to +28V, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at VCC= +7.5V, CS= 1µF, and TA= +25°C.) (Note 2)

)

ELECTRICAL CHARACTERISTICS (continued)

(VCC= +6.0V to +28V, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at VCC= +7.5V, CS= 1µF, and TA= +25°C.) (Note 2)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Driver Short-Circuit Output Current I

Driver Short-Circuit-Foldback Output Current

RECEIVER

Input Current (A and B) I

Receiver Differential Threshold Voltage

Receiver Input Hysteresis ΔV

Output High Voltage V

Output Low Voltage V

Thr ee- S tate O utp ut C ur r ent at Recei ver I

Receiver-Input Resistance R

Receiver-Output Short-Circuit Current I

ESD PROTECTION

ESD Protection (A, B)

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

OSD

I

OSDF

A, B

V

TH

OH

OL

OZR

OSR

0V < V

-7V < V

(VCC - 1V) < V

-7V < V

RE, DE, DE/RE = GND, V

-7V < VCM < +12V (MAX13410E/MAX13411E)

-7V < VLM < +12V (MAX13412E/MAX13413E)

VA + VB = 0V 15 mV

TH

IO = -1mA, VA - VB > V

IO = +1mA, VA - VB < -V

0 < VO < V

-7V < VCM < +12V 96 kΩ

IN

0V < VRO < V

< +12V +250

OUT

< 0V -250

OUT

< +12V 20

OUT

< 0V -20

OUT

VIN = +12V 125

CC

= GND

V

= -7V -100

IN

-200 -50

-100 100

V

TH

REG

- 0.6 V

REG

±8 ±95

Human Body Model (MAX13412E/MAX13413E)

Human Body Model (MAX13410E/MAX13411E)

mA

µA

mV

0.4 V

0.01 ±1 µA

mA

±15 kV

±14 kV

kV

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 f

Driver Enable from Shutdown to Output High

Driver Enable from Shutdown to Output Low

t

DPLH

t

DPHL

t

HL

t

LH

t

DSKEW

MAX

t

DZH(SHDN

t

DZL(SHDN

R

= 54Ω, CL = 50pF,

DIFF

Figures 2a and 3a

R

= 54Ω, CL = 50pF,

DIFF

Figures 2a and 3a

R

= 54Ω, CL = 50pF,

DIFF

Figures 2a and 3a

S2 closed, Figure 4, R

= 500Ω, CL = 100pF

L

S2 closed, Figure 4, R

= 500Ω, CL = 100pF

L

150 1000

250 900

ns

140 ns

500 kbps

11 µs

6µs

MAX13410E–MAX13415E

RS-485 Transceiver with Integrated Low-Dropout Regulator and AutoDirection Control

4 _______________________________________________________________________________________

)

SWITCHING CHARACTERISTICS–MAX13411E

(VCC= +6.0V to +28V, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at VCC= +7.5V, CS= 1µF, and TA= +25°C.) (Note 2)

)

SWITCHING CHARACTERISTICS–MAX13410E (continued)

(VCC= +6.0V to +28V, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at VCC= +7.5V, CS= 1µF, and TA= +25°C.) (Note 2)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Driver Enable to Output High t

Driver Enable to Output Low t

Driver Disable from Output High t

Driver Disable from Output Low t

Time to Shutdown t

RECEIVER

Receiver Propagation Delay

Receiver Output Skew t

Maximum Data Rate f

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

DZH

DZL

DHZ

DLZ

SHDN

t

RPLH

t

RPHL

RSKEW

MAX

RZH

RZL

RZH

RLZ

t

RZH(SHDN

t

RZL(SHDN

S2 closed, Figure 4, R

= 500Ω, CL = 100pF

L

S1 closed, Figure 4, R

= 500Ω, CL = 100pF

L

S2 closed, Figure 4, R

= 500Ω, CL = 100pF

L

S1 closed, Figure 4, R

= 500Ω, CL = 100pF

L

50 340 700 ns

CL = 15pF (at RO), Figures 5 and 6

CL = 15pF (at RO), Figures 5 and 6 30 ns

500 kbps

S2 closed, Figure 7, CL = 15pF 50 ns

S1 closed, Figure 7, CL = 15pF 50 ns

S2 closed, Figure 7, CL = 15pF 50 ns

S1 closed, Figure 7, CL = 15pF 50 ns

S2 closed, Figure 7, CL = 15pF 14 µs

S1 closed, Figure 7, CL = 15pF 3.5 µs

2500 ns

100 ns

200

ns

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 f

Driver Enable from Shutdown to Output High

Driver Enable from Shutdown to Output Low

Driver Enable to Output High t

t

DPLH

t

DPHL

t

HL

t

LH

t

DSKEW

MAX

t

DZH(SHDN

t

DZL(SHDN

DZH

R

= 54Ω, CL = 50pF, Figures 2a

DIFF

and 3a

R

= 54Ω, CL = 50pF, Figures 2a

DIFF

and 3a

R

= 54Ω, CL = 50pF, Figures 2a

DIFF

and 3a

S2 closed, Figure 4, R

= 500Ω, CL = 100pF

L

S2 closed, Figure 4, R

= 500Ω, CL = 100pF

L

S2 closed, Figure 4, R

= 500Ω, CL = 100pF

L

16 Mbps

50

15

ns

8ns

11 µs

6µs

70 ns

MAX13410E–MAX13415E

RS-485 Transceiver with Integrated Low-Dropout

Regulator and AutoDirection Control

_______________________________________________________________________________________ 5

SWITCHING CHARACTERISTICS–MAX13411E (continued)

(VCC= +6.0V to +28V, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at VCC= +7.5V, CS= 1µF, and TA= +25°C.) (Note 2)

)

SWITCHING CHARACTERISTICS–MAX13412E

(VCC= +6.0V to +28V, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at VCC= +7.5V, CS= 1µF, and TA= +25°C.) (Note 2)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Driver Enable to Output Low t

Driver Disable from Output High t

Driver Disable from Output Low t

RECEIVER

Receiver Propagation Delay

Receiver Output Skew t

Maximum Data Rate f

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

DZL

DHZ

DLZ

t

RPLH

t

RPHL

RSKEW

MAX

RZH

RZL

RZH

RLZ

t

RZH(SHDN

t

RZL(SHDN

S1 closed, Figure 4, R

= 500Ω, CL = 100pF

L

S2 closed, Figure 4, R

= 500Ω, CL = 100pF

L

S1 closed, Figure 4, R

= 500Ω, CL = 100pF

L

CL = 15pF (at RO), Figures 5 and 6

CL = 15pF (at RO), Figures 5 and 6 8 ns

S2 closed, Figure 7, CL = 15pF 50 ns

S1 closed, Figure 7, CL = 15pF 50 ns

S2 closed, Figure 7 , CL = 15pF 50 ns

S1 closed, Figure 7, CL = 15pF 50 ns

S2 closed, Figure 7, CL = 15pF 14 µs

S1 closed, Figure 7, CL = 15pF 3.5 µs

70 ns

50 ns

75

16 Mbps

ns

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

DRIVER

Driver Propagation Delay

Driver Differential Output Rise or Fall Time

Maximum Data Rate f

Driver Disable Delay t

RECEIVER

Receiver Propagation Delay

Receiver Output Skew t

Maximum Data Rate f

Receiver Enable to Output High t

Receiver Enable to Output Low t

t

DPLH

t

DPHL

t

HL

t

LH

MAX

DDD

t

RPLH

t

RPHL

RSKEW

MAX

RZH

RZL

RL = 110Ω, CL = 50pF, Figures 2b and 3b

RL = 110Ω, CL = 50pF, Figure 3b 2500 ns

CL = 15pF, Figures 5 and 6

CL = 15pF, Figures 5 and 6 30 ns

S2 closed, Figure 7, CL = 15pF 50 ns

S1 closed, Figure 7, CL = 15pF 50 ns

200 1000

250 900

500 kbps

200

500 kbps

ns

MAX13410E–MAX13415E

RS-485 Transceiver with Integrated Low-Dropout Regulator and AutoDirection Control

6 _______________________________________________________________________________________

SWITCHING CHARACTERISTICS–MAX13412E (continued)

(VCC= +6.0V to +28V, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at VCC= +7.5V, CS= 1µF, and TA= +25°C.) (Note 2)

SWITCHING CHARACTERISTICS–MAX13413E

(VCC= +6.0V to +28V, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at VCC= +7.5V, CS= 1µF, and TA= +25°C.) (Note 2)

SWITCHING CHARACTERISTICS–MAX13414E

(VCC= +6.0V to +28V, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at VCC= +7.5V, CS= 1µF, and TA= +25°C.) (Note 2)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Receiver Disable Time from Low t

Receiver Disable Time from High t

Receiver Enable Delay t

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

DRIVER

Driver Propagation Delay

Driver Differential Output Rise or Fall Time

Maximum Data Rate f

Driver Disable Delay t

RECEIVER

Receiver Propagation Delay

Receiver Output Skew t

Maximum Data Rate f

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 Delay t

RLZ

RZH

RED

t

DPLH

t

DPHL

t

HL

t

LH

MAX

DDD

t

RPLH

t

RPHL

RSKEW

MAX

RZH

RZL

RLZ

RZH

RED

S1 closed, Figure 7, CL = 15pF 50 ns

S2 closed, Figure 7, CL = 15pF 50 ns

RL = 110Ω, CL = 50pF, Figure 3 2500 ns

RL = 110Ω, CL = 50pF, Figures 2b and 3b

16 Mbps

RL = 110Ω, CL = 50pF, Figure 3b 70 ns

CL = 15pF, Figures 5 and 6

CL = 15pF, Figures 5 and 6 13 ns

16 Mbps

S2 closed, Figure 7, CL = 15pF 50 ns

S1 closed, Figure 7, CL = 15pF 50 ns

S2 closed, Figure 7, CL = 15pF 50 ns

RL = 110Ω, Figure 3, CL = 50pF 70 ns

50

15

80

ns

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

DRIVER

Driver Propagation Delay

Driver Differential Output Rise or Fall Time

Driver Differential Output Skew |t

- t

DPHL

|

DPLH

t

DPLH

t

DPHL

t

HL

t

LH

t

DSKEW

R

= 54Ω, CL = 50pF, Figures 2a

DIFF

and 3a

R

= 54Ω, CL = 50pF, Figures 2a

DIFF

and 3a

R

= 54Ω, CL = 50pF, Figures 2a

DIFF

and 3a

200 1000

250 900

ns

140 ns

MAX13410E–MAX13415E

RS-485 Transceiver with Integrated Low-Dropout

Regulator and AutoDirection Control

_______________________________________________________________________________________ 7

SWITCHING CHARACTERISTICS–MAX13414E (continued)

(VCC= +6.0V to +28V, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at VCC= +7.5V, CS= 1µF, and TA= +25°C.) (Note 2)

SWITCHING CHARACTERISTICS–MAX13415E

(VCC= +6.0V to +28V, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at VCC= +7.5V, CS= 1µF, and TA= +25°C.) (Note 2)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Maximum Data Rate f

Driver Enable to Output High t

Driver Enable to Output Low t

Driver Disable from Output High t

Driver Disable from Output Low t

RECEIVER

Receiver Propagation Delay

Receiver Output Skew t

Maximum Data Rate f

Receiver Enable to Output High t

Receiver Enable to Output Low t

Receiver Disable Time from Low t

Receiver Disable Time from High t

MAX

DZH

DZL

DHZ

DLZ

t

RPLH

t

RPHL

RSKEW

MAX

RZH

RZL

RLZ

RZH

S2 closed, Figure 4,

= 500Ω CL = 100pF

R

L

S1 closed, Figure 4,

= 500Ω CL = 100pF

R

L

S2 closed, Figure 4,

= 500Ω, CL = 100pF

R

L

S1 closed, Figure 4,

= 500Ω, CL = 100pF

R

L

CL = 15pF (at RO), Figures 5 and 6

CL = 15pF (at RO), Figures 5 and 6 30 ns

S2 closed, Figure 7, CL = 15pF 50 ns

S1 closed, Figure 7, CL = 15pF 50 ns

S2 closed, Figure 7, CL = 15pF 50 ns

500 kbps

2500 ns

100 ns

200

ns

500 kbps

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

DRIVER

Driver Propagation Delay

Driver Differential Output Rise or Fall Time

Driver Differential Output Skew |t

- t

DPHL

|

DPLH

Maximum Data Rate f

Driver Enable to Output High t

Driver Enable to Output Low t

Driver Disable from Output High t

t

DPLH

t

DPHL

t

HL

t

LH

t

DSKEW

MAX

DZH

DZL

DHZ

R

= 54Ω, CL = 50pF, Figures 2a

DIFF

and 3a

R

= 54Ω, CL = 50pF, Figures 2a

DIFF

and 3a

R

= 54Ω, CL = 50pF, Figures 2a

DIFF

and 3a

S2 closed, Figure 4,

= 500Ω, CL = 15pF

R

L

S1 closed, Figure 4,

= 500Ω, CL = 15pF

R

L

S2 closed, Figure 4,

= 500Ω, CL = 15pF

R

L

50

15

ns

8ns

16 Mbps

70 ns

50 ns

MAX13410E–MAX13415E

RS-485 Transceiver with Integrated Low-Dropout Regulator and AutoDirection Control

8 _______________________________________________________________________________________

SWITCHING CHARACTERISTICS–MAX13415E (continued)

(VCC= +6.0V to +28V, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at VCC= +7.5V, CS= 1µF, and TA= +25°C.) (Note 2)

Note 2: CSis the compensation capacitor on V

REG

for the MAX13412E–MAX13415E versions. CSmust have an ESR value of 20mΩ or less.

Note 3: Parameters are guaranteed for +6.0V ≤ V

CC

≤ +28V.

Typical Operating Characteristics

(VCC= +7.5V, TA= +25°C, unless otherwise noted.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Driver Disable from Output Low t

RECEIVER

Receiver Propagation Delay

Receiver Output Skew t

Maximum Data Rate f

Receiver Enable to Output High t

Receiver Enable to Output Low t

Receiver Disable Time from Low t

Receiver Disable Time from High t

DLZ

t

RPLH

t

RPHL

RSKEW

MAX

RZH

RZL

RLZ

RZH

S1 closed, Figure 4,

= 500Ω, CL = 15pF

R

L

CL = 15pF (at RO), Figures 5 and 6

CL = 15pF (at RO), Figures 5 and 6 8 ns

16 Mbps

S2 closed, Figure 7, CL = 15pF 50 ns

S1 closed, Figure 7, CL = 15pF 50 ns

S2 closed, Figure 7, CL = 15pF 50 ns

50 ns

75

ns

SUPPLY CURRENT

vs. TEMPERATURE

8.0 NO LOAD

6.0

4.0

SUPPLY CURRENT (mA)

2.0

DE = HIGH

DE = LOW

MAX13410E-15E toc01

OUTPUT CURRENT (mA)

vs. RECEIVER OUTPUT HIGH VOLTAGE

35

30

25

20

15

10

5

OUTPUT CURRENT

60

50

MAX13410E-15E toc02

40

30

20

OUTPUT CURRENT (mA)

10

vs. RECEIVER OUTPUT LOW VOLTAGE

MAX13410E-15E toc03

0

-40 10-15 35 60 85 TEMPERATURE (°C)

0

021345

OUTPUT HIGH VOLTAGE (V)

0

05

OUTPUT LOW VOLTAGE (V)

2134

MAX13410E–MAX13415E

RS-485 Transceiver with Integrated Low-Dropout

Regulator and AutoDirection Control

_______________________________________________________________________________________

9

Typical Operating Characteristics (continued)

(VCC= +7.5V, TA= +25°C, unless otherwise noted.)

RECEIVER OUTPUT HIGH VOLTAGE

IO = +1mA

R

= 54Ω

DIFF

vs. TEMPERATURE

MAX13410E-15E toc04

OUTPUT LOW VOLTAGE (V)

TEMPERATURE (°C)

vs. TEMPERATURE

120

100

MAX13410E-15E toc07

OUTPUT CURRENT (mA)

TEMPERATURE (°C)

5.4

5.2

5.0

4.8

4.6

4.4

OUTPUT HIGH VOLTAGE (V)

4.2

4.0

-40 10-15 35 60 85

DRIVER DIFFERENTIAL OUTPUT VOLTAGE

4.0

3.5

3.0

2.5

2.0

1.5

1.0

DIFFERENTIAL OUTPUT VOLTAGE (V)

0.5

0

-40 10-15 35 60 85

RECEIVER OUTPUT LOW VOLTAGE

vs. TEMPERATURE

0.5 IO = -1mA

0.4

0.3

0.2

0.1

0

-40 10-15 35 60 85

TEMPERATURE (°C)

OUTPUT CURRENT

vs. TRANSMITTER OUTPUT HIGH VOLTAGE

80

60

40

20

0

-7 -5 -4 -3-6 -2 0-1 12345 OUTPUT HIGH VOLTAGE (V)

80

60

MAX13410E-15E toc05

40

OUTPUT CURRENT (mA)

20

120

100

MAX13410E-15E toc08

80

60

40

OUTPUT CURRENT (mA)

20

DIFFERENTIAL OUTPUT CURRENT

vs. DIFFERENTIAL OUTPUT VOLTAGE

0

021 345

OUTPUT VOLTAGE (V)

OUTPUT CURRENT

vs. TRANSMITTER OUTPUT LOW VOLTAGE

0

0462 8 10 12

OUTPUT LOW VOLTAGE (V)

MAX13410E-15E toc06

MAX13410E-15E toc09

SHUTDOWN CURRENT

vs. TEMPERATURE

100

90

80

70

60

50

40

30

SHUTDOWN CURRENT (μA)

20

10

0

-40 10-15 35 60 85

TEMPERATURE (°C)

DRIVER PROPAGATION vs. TEMPERATURE

700

RL = 110Ω

600

MAX13410E-15E toc10

500

400

300

200

DRIVER PROPAGATION DELAY (ns)

100

0

-40 10-15 35 60 85

(MAX13412E)

t

RPLH

t

RPHL

TEMPERATURE (°C)

DRIVER PROPAGATION vs. TEMPERATURE

40

RL = 110Ω

35

30

MAX13410E-15E toc11

25

20

15

10

DRIVER PROPAGATION DELAY (ns)

5

0

-40 10-15 35 60 85

(MAX13413E)

t

RPHL

t

RPLH

TEMPERATURE (°C)

MAX13410E-15E toc12

MAX13410E–MAX13415E

RS-485 Transceiver with Integrated Low-Dropout Regulator and AutoDirection Control

10 ______________________________________________________________________________________

Typical Operating Characteristics (continued)

(VCC= +7.5V, TA= +25°C, unless otherwise noted.)

RECEIVER PROPAGATION vs.TEMPERATURE

(MAX13410E/MAX13412E)

60

t

45

30

15

RECEIVER PROPAGATION DELAY (ns)

0

-40 10-15 35 60 85

RPHL

t

RPLH

TEMPERATURE (°C)

MAX13410E-15E toc13

DRIVER PROPAGATION (16kbps)

(MAX13413E)

MAX13410E-15E toc16

DI 2V/div

A - B 5V/div

RECEIVER PROPAGATION vs.TEMPERATURE

(MAX13411E/MAX13413E)

60

45

30

15

RECEIVER PROPAGATION DELAY (ns)

0

-40 10-15 35 60 85 TEMPERATURE (°C)

RECEIVER PROPAGATION (16kbps)

(MAX13413E)

t

RPHL

t

RPLH

MAX13410E-15E toc17

MAX13410E-15E toc14

A 2V/div

B 2V/div

RO 2V/div

DRIVER PROPAGATION (250kbps)

(MAX13412E)

1μs/div

MAX13410E-15E toc15

DRIVING A LARGE CAPACITIVE LOAD 16nF

(19.2kbps) (MAX13412E)

MAX13410E-15E toc18

DI 2V/div

A - B 5V/div

DI 2V/div

A - B 2V/div

20ns/div

DRIVING A LARGE CAPACITIVE LOAD 16nF

(1Mbps) (MAX13413E)

400ns/div

MAX13410E-15E toc19

DI 2V/div

A - B 5V/div

20ns/div

DRIVING A LARGE CAPACITIVE LOAD 16nF

(50kbps) (MAX13413E)

1μs/div

MAX13410E-15E toc20

10μs/div

DI 2V/div

A - B 2V/div

MAX13410E–MAX13415E

RS-485 Transceiver with Integrated Low-Dropout

Regulator and AutoDirection Control

______________________________________________________________________________________ 11

Figure 1. Driver DC Test Load

Figure 3a. Driver Propagation Delays

Test Circuits and Waveforms

Figure 2a. Driver-Timing Test Circuit

Figure 2b. Driver-Timing Test Circuit

A

V

OD

B

5V

DE

A

DI

B

/ 2

R

DIFF

C

L

V

R

/ 2

OC

DIFF

R

L

A

V

ID

R

DIFF

C

L

DI

V

ID

B

V

REG

GND

R

C

L

5V

DI

0

B

A

1/2 V

V

O

V

O

V

0

DIFF

-V

O

LH

10%

f = 1MHz, tLH ≤ 3ns, tHL ≤ 3ns

B

DPHL

1.5V

1/2 V

t

DPHL

90%

t

HLt

|

O

10%

1.5V

t

DPLH

O

= VA - V

V

DIFF

90%

t

= |t

DPLH

- t

DSKEW

MAX13410E–MAX13415E

RS-485 Transceiver with Integrated Low-Dropout Regulator and AutoDirection Control

12 ______________________________________________________________________________________

Test Circuits and Waveforms (continued)

Figure 3b. Driver Propagation Delays

Figure 4. Driver Enable and Disable Times

Figure 5. Receiver-Propagation-Delay Test Circuit

f = 1MHz, tLH ≤ 3ns, tHL ≤ 3ns

RE = V

5V

DI

0

B

V

O

A

1/2 V

1.5V

O

CC

t

DPLH

t

DPHL

1.5V

1/2 V

O

RO

O

V

O

V

DIFF

0

-V

O

OUTPUT

UNDER TEST

500Ω

C

L

(RO PULLED LOW)

10%

t

LH

5V

S

1

S

2

t

, t

DDD

RED

90%

V

CC

DE

0

A, B

V

OL

A, B

0

V

DIFF

= VA - V

1.5V

2.3V

B

t

DZL(SHDN)

t

DZH(SHDN)

90%

t

HL

OUTPUT NORMALLY LOW

OUTPUT NORMALLY HIGH

10%

1.5V

t

DLZ

V

+ 0.5V

OL

V

OH

+ 0.5V

V

OH

t

DHZ

B

RECEIVER

ATE

V

ID

R

OUTPUT

A

MAX13410E–MAX13415E

RS-485 Transceiver with Integrated Low-Dropout

Regulator and AutoDirection Control

______________________________________________________________________________________ 13

Test Circuits and Waveforms (continued)

Figure 6. Receiver Propagation Delays

Figure 7. Receiver Enable and Disable Times

A

B

V

OH

RO

V

OL

C

L

15pF

1kΩ

RO

S

1

S

2

f = 1MHz, t

t

RPHL

1.5V

V

REG

RE

0

V

REG

RO

5V

0

V

REG

RO

0

DI = 0V

≤ 3ns, tHL ≤ 3ns

LH

t

= | t

RSKEW

RPHL

1.5V

t

RZL(SHDN)

2.3V

t

RZH(SHDN)

1V

-1V

t

RPLH

1.5V

- t

RPLH |

1.5V

, t

RZL

OUTPUT NORMALLY LOW

OUTPUT NORMALLY HIGH

, t

t

RZH

t

RHZ

+ 0.5V

V

OH

+ 0.5V

V

OH

RHZ

MAX13410E–MAX13415E

RS-485 Transceiver with Integrated Low-Dropout Regulator and AutoDirection Control

14 ______________________________________________________________________________________

Pin Description

MAX13410E/

MAX13411E

NAME FUNCTION

1—1RO

Receiver Output. When receiver is enabled and V

A

- VB ≥ -50mV,

RO is high. If V

A

- VB ≤ -200mV, RO is low. Note: RO is referenced to

the LDO output (V

REG

).

2——RE

Receiver Output Enable. Drive RE low to enable RO. Drive RE high to disable the RO output and put the RO output in a high-impedance state.

3——DE

D r i ver Outp ut E nab l e. D r i ve D E l ow to p ut the d r i ver outp ut i n thr ee- state. D r i ve D E hi g h to enab l e the d r i ver .

444DI

Driver Input. Drive DI low to force the noninverting output low and the inverting output high. Drive DI high to force the noninverting output high and inverting output low. DI is an input to the internal state machine that automatically enables and disables the driver (for the MAX13412E/MAX13413E). See the function tables and General Description for more information.

5 5 5 GND Ground

6 6 6 A Noninverting Receiver Input and Noninverting Driver Output

7 7 7 B Inverting Receiver Input and Inverting Driver Output

888V

CC

Positive Supply. Bypass VCC with a 0.1µF ceramic capacitor to GND.

—1—RO

Receiver Output. When receiver is enabled and V

A

- VB ≥ -100mV,

RO is high. If V

A

- VB ≤ -100mV, RO is low. Note: RO is referenced to

the LDO output (V

REG

).

—2—RE

Receiver Output Enable. Drive RE low to force the RO output to be enabled. Drive RE high to let the AutoDirection circuit control RO.

—3 3V

REG

LDO Output. V

REG

is fixed at +5V. Bypass V

REG

with a low ESR

(20mΩ or less) and a 1µF (min) ceramic capacitor.

— — 2 DE/RE

Receiver and Driver Output Enable. Drive DE/RE low to enable RO and disable the driver. Drive DE/RE high to disable RO and enable the driver.

EP EP EP EP

Exposed Pad. EP is internally connected to GND. For enhanced thermal dissipation, connect EP to a copper area as large as possible. Do not use EP as a sole ground connection.

MAX13412E/

MAX13413E

MAX13414E/

MAX13415E

MAX13410E–MAX13415E

RS-485 Transceiver with Integrated Low-Dropout

Regulator and AutoDirection Control

______________________________________________________________________________________ 15

Function Tables for the MAX13410E/MAX13411E

X

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

Function Tables for the MAX13414E/MAX13415E

X

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

Function Tables for the MAX13412E/MAX13413E

X

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

TRANSMITTING

INPUT OUTPUT

RE DE DI B A

X11 0 1

X10 1 0

0 0 X High impedance High impedance

1 0 X High impedance (shutdown)

RE DE A - B RO

0X > -50mV 1

0X < -200mV 0

0 X Open/Short 1

1 1 X High impedance

10 X

INPUT OUTPUT

RECEIVING

TRANSMITTING

INPUTS OUTPUTS

DI A - B > V

0 X Turn driver ON 0 1

1 False If driver was OFF, keep it OFF High impedance High impedance

1 False If driver was ON, keep it ON 1 0

1 True Turn driver OFF High impedance High impedance

DT

ACTION A B

High impedance

(shutdown)

RECEIVING

INPUTS OUTPUT

RE A - B DRIVER STATE RECEIVER STATE RO

0 > -100mV X ON 1

0 < -100mV X ON 0

1 X ON OFF High impedance

1 > -100mV OFF ON 1

1 < -100mV OFF ON 0

TRANSMITTING

INPUT OUTPUT

DE/RE DI B A

0 X High impedance High impedance

11 0 1

10 1 0

DE/RE A - B RO

INPUT OUTPUT

0 > -50mV 1

0 < -200mV 0

0 Open/Short 1

1 X High impedance

RECEIVING

MAX13410E–MAX13415E

Detailed Description

The MAX13410E–MAX13415E are half-duplex RS-485/ RS-422-compatible transceivers optimized for isolated applications. These devices feature an internal LDO regulator, one driver, and one receiver. The internal LDO allows the part to operate from an unregulated +6V to +28V power supply. The AutoDirection feature reduces the number of optical isolators needed in isolated applications. Other features include ±15kV ESD protection (MAX13412E/MAX13413E only), ±14kV (MAX13410E/ MAX13411E only) fail-safe circuitry, slew-rate limiting, and full-speed operation.

The MAX13410E–MAX13415E internal LDO generates a 5V ±10% power supply that is used to power its internal circuitry. The MAX13412E–MAX13415E bring the 5V to an output V

REG

that allows the user to power additional external circuitry with up to 20mA to further reduce external components. The MAX13410E/MAX13411E do not have a 5V output and come in industry-compatible pinouts. This allows easy replacement in existing designs.

The MAX13412E/MAX13413E feature Maxim’s proprietary AutoDirection control. This architecture eliminates the need for the DE and RE control signals. In isolated applications, this reduces the cost and size of the system by reducing the number of optical isolators required.

The MAX13410E/MAX13412E/MAX13414E feature reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, allowing error-free transmission up to 500kbps. The MAX13411E/MAX13413E/MAX13415E are not slew-rate limited, allowing transmit speeds up to 16Mbps.

The MAX13410E–MAX13415E feature a 1/8-unit load receiver input impedance, allowing up to 256 transceivers on the bus. All driver outputs are protected to ±15kV ESD using the Human Body Model. These devices also include fail-safe circuitry, MAX13410E/ MAX13411E/MAX13414E/MAX13415E, guaranteeing a logic-high receiver output when the receiver inputs are open or shorted. The receiver outputs a logic-high when the transmitter on the terminated bus is disabled (high impedance).

Internal Low-Dropout Regulator

The MAX13410E–MAX13415E include an internal lowdropout regulator that allows it to operate from input voltages of up to +28V. The internal LDO has a set output voltage of 5V ±10% that is used to power the internal circuitry of the device. The MAX13412E–MAX13415E offer the LDO output at the V

REG

output. This allows additional external circuitry to be powered without the need for additional external regulators. The V

REG

output can

source up to 20mA.

When using these devices with high input voltages and heavily loaded networks, special care must be taken that the power dissipation rating of the package and the maximum die temperature of the device is not exceeded. Die temperature of the part can be calculated using the equation:

T

DIE

= [(

θ

JC

+

θ

CA

) x P

DISS

] + T

AMBIENT

, where

T

DIE

= Temperature of the Die

θ

JC

= 6.0°C/W = Junction-to-Case Thermal Resist-

ance

θ

CA

= Case-to-Ambient Thermal Resistance

θ

JA

=

θ

JC

+

θ

CA

= 52.0°C/W = Junction-to-Ambient

Thermal Resistance

P

DISS

= (ICC- VCC) + [(VCC- V

REG

) x I

REG

)] + [(VCC-

VOD) x I

DRIVER

] = Power Dissipation of the Part

T

AMBIENT

= Ambient Temperature

VCC= Voltage on the VCCInput

ICC= Current in to V

CC

V

REG

= Voltage on the V

REG

Output

I

REG

= Current Drawn from the V

REG

Output

VOD= Voltage at the Driver Output (|VA- VB|)

I

DRIVER

= Current Driven Out of the Driver. Typically,

this is the current through the termination resistor.

The absolute maximum rating of the die temperature of the MAX13410E–MAX13415E is +150°C. To protect the part from overheating, there is an internal thermal shutdown that shuts down the part when the die temperature reaches +150°C. To prevent damage to the part, and to prevent the part from entering thermal shutdown, keep the die temperature below +150°C, plus some margin. The circuit designer can minimize the die temperature by controlling the following parameters:

•V

CC

•I

REG

•

θ

CA

Measuring the VCCCurrent

Measured current at the VCCpin is a function of the quiescent current of the part, the amount of current that the drivers must supply to the load, and in the case of the MAX13412E–MAX13415E, the load on the V

REG

output. In most cases, the load that the drivers must supply will be the termination resistor(s). Ideally, the termination resistance should match the characteristic impedance of the cable and is usually not a parameter the circuit designer can easily change. In some lowspeed, short-cable applications, proper termination

RS-485 Transceiver with Integrated Low-Dropout Regulator and AutoDirection Control

16 ______________________________________________________________________________________

may not be necessary. In these cases, the drive current can be reduced to minimize the die temperature.

Minimizing the load on the V

REG

output lowers the power dissipation of the part and ultimately reduces the maximum die temperature.

θθ

CA

θ

CA

is the thermal resistance from case to ambient and

is independent of the MAX13410E–MAX13415E.

θ

CA

is

primarily a characteristic of the circuit-board design. The

largest contributing factor of

θ

CA

will be the size and weight of the copper connected to the exposed paddle of the MAX13410E–MAX13415E. Lower the thermal resistance by using as large a pad as possible. Additionally, vias can be used to connect the pad to other ground planes in the circuit board.

Note that

θ

JC

is the thermal resistance of the part from junction-to-case temperature and is fixed at 6.0°C/W. It is solely based on the die and package characteristics of

MAX13410E–MAX13415E

RS-485 Transceiver with Integrated Low-Dropout

Regulator and AutoDirection Control

______________________________________________________________________________________ 17

Functional Diagrams

Functional Diagram for the MAX13410E/MAX13411E/MAX13414E/MAX13415E

Functional Diagram for the MAX13412E/MAX13413E

DERO3

1

2

4

MAX13410E MAX13411E

+

R

1

RO

2

LDO

87V

CC

BRE

6

A

D

5

GNDDI

RO

V

REG

V

MAX13412E MAX13413E

RE

REG

V

REG

R

RE

1

2

3

4

+

-

+

LDO

MAX13414E MAX13415E

R

D

LDO

87V

CC

BDE/RE

6

A

5

GNDDI

V

8

CC

3

V

REG

STATE

RI

MACHINE

DI

4

DI

7

GND

B

6

A

5

-

V

COM

DT

+

DE

V

REG

D

MAX13410E–MAX13415E

the MAX13410E–MAX13415E. The circuit-board designer has no control over this parameter.

Fail Safe

The MAX13410E/MAX13411E/MAX13414E/MAX13415E 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 0 by the termination. With the receiver thresholds of the MAX13410E/ MAX13411E/MAX13414E/MAX13415E, the result 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.

AutoDirection Circuitry

The AutoDirection circuitry in the MAX13412E/ MAX13413E is a technique to minimize the number of signals needed to drive the part. This is especially useful in very low cost, isolated systems. In a typical isolated system, an optocoupler is used for each control signal to cross the isolation barrier. These optocouplers add cost, size and consume power. Without the AutoDirection circuitry, three to four optocouplers may be required for each transceiver. With the AutoDirection circuitry, the number of optocouplers can be reduced to two.

Typical RS-485 transceivers have four signals on the control side of the part. These are RO (receiver output), RE (receiver enable), DE (driver enable), and DI (driver input). In some cases, DE and RE may be connected together to reduce the number of control signals to three. In half-duplex systems, the RE and DE signals determine if the part is transmitting or receiving. When the part is receiving, the transmitter is in a high-impedance state. In a fully compliant RS-485 system, all three or four signals are required. However, with careful design and Maxim’s AutoDirection feature, the number of control signals can be reduced to just RO and DI in an RS-485 compatible system. This feature assumes the DI input idles in the high state while the receiver portion of the MAX13412E/MAX13413E is active. It also requires an external pullup resistor on A and pulldown resistor on B (see the typical application circuit, Figure 10). The following is a description of how AutoDirection works.

When DI is low, the MAX13412E/MAX13413E always drive the bus low. When DI transitions from a low to a

high, the drivers actively drive the output until (A - B) > VDT. Once (A - B) is greater than VDT, the drivers are disabled, letting the pullup/pulldown resistors hold the A and B lines in the correct state. This allows other transmitters on the bus to pull the bus low.

Pullup and Pulldown Resistors

The pullup and pulldown resistors on the A and B lines are required for proper operation of the MAX13412E and MAX13413E, although their exact value is not critical. They function to hold the bus in the high state (A - B > 200mV) when all the transmitters are in a high-impedance state due to either a shutdown condition or AutoDirection. Determining the best value to use for these resistors depends on many factors, such as termination resistor values, noise, number of transceivers on the bus, etc. Size these resistors so that, under all conditions, (A - B) > 200mV for ALL receivers on the bus.

Idle State

When not transmitting data, the MAX13412E/ MAX13413E require the DI input to be driven high to remain in the idle state. A conventional RS-485 transceiver has DE and RE inputs that are used to enable and disable the driver and receiver. However, the MAX13412E/MAX13413E do not have a DE input, and instead use an internal state machine to enable and disable the drivers. DI must be driven high to go to the idle state.

Enhanced 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 MAX13410E– MAX13415E have extra protection against static electricity. Maxim’s engineers have developed state-of-the-art structures to protect these pins against ESD of ±15kV (MAX13412E/MAX13413E) and ±14kV (MAX13410E/ MAX13411E) without damage. The ESD structures withstand high ESD in all states: normal operation, shutdown, and powered down. After an ESD event, the MAX13410E– MAX13415E keep working without latchup or damage.

ESD protection can be tested in various ways. The transmitter outputs and receiver inputs of the MAX13410E– MAX13415E are characterized for protection to the following limits:

±15kV using the Human Body Model (MAX13412E/ MAX13413E)

±14kV using the Human Body Model (MAX13410E/ MAX13411E)

RS-485 Transceiver with Integrated Low-Dropout Regulator and AutoDirection Control

18 ______________________________________________________________________________________

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 8a shows the Human Body Model, and Figure 8b 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.

Applications Information

Typical Applications

The MAX13410E–MAX13415E transceivers are designed for half-duplex, bidirectional data communications on multipoint bus transmission lines. 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 MAX13410E/ MAX13412E/MAX13414E are more tolerant of imperfect termination.

Typical Application Circuit for the

MAX13410E and MAX13411E

This application circuit shows the MAX13410E/ MAX13411E being used in an isolated application (see Figure 9). The MAX13410E/MAX13411E use the industrystandard pin out but do not have a V

REG

output for biasing external circuitry. The positive temperature coefficient (PTC) and transient voltage suppressor (TVS) clamp circuit on the RS-485 outputs are intended to provide overvoltage fault protection and are optional based on the requirements of the design.

Typical Application Circuit for the

MAX13412E and MAX13413E

This application circuit shows the MAX13412E and MAX13413E being used in an isolated application where the AutoDirection feature is implemented to reduce the number of optical isolators to two (see Figure 10). The MAX13412E/MAX13413E provide a V

REG

output that can be used to power external circuit-

ry up to 20mA.

Typical Application Circuit for the

MAX13414E and MAX13415E

This application circuit shows the MAX13414E/ MAX13415E being used in an isolated application using an unregulated power supply with three optical isolators (see Figure 11). The MAX13414E/MAX13415E provide a V

REG

output that can be used to power external circuitry

up to 20mA.

256 Transceivers on the Bus

The RS-485 standard specifies the load each receiver places on the bus in terms of unit loads. An RS-485compliant transmitter can drive 32 one-unit load receivers when used with a 120Ω cable that is terminated on both ends over a -7V to +12V common-mode range. The MAX13410E–MAX13415E are specified as 1/8 unit loads. This means a compliant transmitter can drive up to 256 devices of the MAX13410E–MAX13415E. Reducing the common mode, and/or changing the characteristic impedance of the cable, changes the maximum number of receivers that can be used. Refer to the TIA/EIA-485 specification for further details.

Proper Termination and Cabling/

Wiring Configurations

When the data rates for RS-485 are high relative to the cable length it is driving, the system is subject to proper

MAX13410E–MAX13415E

RS-485 Transceiver with Integrated Low-Dropout

Regulator and AutoDirection Control

______________________________________________________________________________________ 19

Figure 8a. Human Body ESD Test Model

Figure 8b. Human Body Current Waveform

R

C

1MΩ

CHARGE-CURRENT-

LIMIT RESISTOR

HIGH-

VOLTAGE

DC

SOURCE

100pF

C

s

R

D

1500Ω

DISCHARGE RESISTANCE

STORAGE CAPACITOR

DEVICE UNDER

TEST

IP 100%

90%

AMPS

36.8%

10%

0

t

RL

TIME

CURRENT WAVEFORM

I

r

t

DL

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

MAX13410E–MAX13415E

transmission line design. In most cases, a single, controlled-impedance cable or trace should be used and should be properly terminated on both ends with the characteristic impedance of the cable/trace. RS-485 transceivers should be connected to the cable/ traces with minimum-length wires to prevent stubs. Star configurations and improperly terminated cables can cause data loss. Refer to the

Application Notes

section of the Maxim website or to TIA/EIA publication TSB-89-A for further information. While proper termination is always desirable, in some cases, such as when data rates are very low, it may be desirable and advantageous to not properly terminate the cables. In such cases, it is up to the designer to ensure that the improper termination and resultant reflections (etc.) will not corrupt the data.

Reduced EMI and Reflections

The MAX13410E/MAX13412E/MAX13414E feature 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 in the MAX13410E/MAX13411E by driving DE low and driving

RE high. In shutdown, the devices draw 65µA (typ) of supply current.

The devices are guaranteed not to enter shutdown if DE is low (while RE is high) for less than 50ns. If the inputs are in this state for at least 700ns, the devices are guaranteed to enter shutdown.

Enable times t

ZH

and tZL(see the switching characteristics table) assume the devices were not in a low-power shutdown 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 Telecommunications Industry Association (TIA) published the document TSB-89-A:

Application Guidelines

for TIA/EIA-485-A

, which is a good reference for deter-

mining maximum data rate vs. line length.

Isolated RS-485 Interface

An isolated RS-485 interface electrically isolates different nodes on the bus to protect the bus from problems due to high common-mode voltages that exceed the RS-485 common-mode voltage range, conductive noise, and

RS-485 Transceiver with Integrated Low-Dropout Regulator and AutoDirection Control

20 ______________________________________________________________________________________

Figure 9. Typical Application Circuit for the MAX13410E/MAX13411E

R

t

UNREGULATED ISOLATED

+

RO

1

RE

2

POWER SUPPLY

R

LDO

ISO_V

V

CC

8

B

7

CC

0.1μF

V

SYS

MCU AND

ISO_V

CC

N

CC

ISO_V

CC

DE

3

DI

4

D

MAX13410E MAX13411E

A

6

GND

5

R

t

ground loops. The typical application circuits show an isolated RS-485 interface using the MAX13410E– MAX13415E. The transceiver is powered separately from the controlling circuitry. The AutoDirection feature of the MAX13412E/MAX13413E (see the

AutoDirection Circuitry

section) requires only two optocouplers to electrically isolate the transceiver.

An isolated RS-485 interface electrically isolates different nodes on the bus to protect the bus from problems due to high common-mode voltages that exceed the RS-485 common-mode voltage range. An isolated RS485 interface has two additional design challenges not normally associated with RS-485 design. These are 1) isolating the control signals and 2) getting isolated power to the transceiver. Optical isolators are the most common way of getting the control signals across the isolation barrier.

Isolated power is typically done using a transformer in either a push-pull or flyback configuration. The MAX845 is an example of an inexpensive, unregulated push-pull converter (see Figure 12). While in theory, the output of an unregulated push-pull converter is predictable, the output voltage can vary significantly due to the non-ideal

characteristics of the transformer, load variations, and temperature drift of the diodes, etc. Variances of ±20% or more would not be uncommon. This would require the addition of a linear regulator to get standard RS-485 transceivers to work. Since the MAX13410E– MAX13415E have the linear regulator built in, this external regulator and its associated cost and size penalties are not necessary. A nominal +7.5V output with a ±20% tolerance would provide a +6V to +9V supply voltage. This is well within the operating range of the MAX13410E–MAX13415E. If the output tolerance is even greater than ±20%, adjust the design of the power supply for a higher output voltage to ensure the minimum input voltage requirements are met.

Flyback converters are typically regulated. A TL431 type error amplifier and an optical isolator usually close the loop. The MAX5021 is an example of a small, inexpensive, flyback controller (see Figure 13). While the primary output of the flyback converter is tightly regulated, secondary outputs will not be. As with the unregulated push-pull converter, the MAX13410E–MAX13415E are ideally suited for use with these secondary outputs.

MAX13410E–MAX13415E

RS-485 Transceiver with Integrated Low-Dropout

Regulator and AutoDirection Control

Figure 10. Typical Application Circuit for the MAX13412E/MAX13413E

______________________________________________________________________________________ 21

ISO_V

MCU AND

CC

V

SYS

ISO_V

CC

ISO_V

CC

ISO_V

CC

C

1μF

V

SYS

S

RO

1

RE

2

V

REG

3

DI

4

UNREGULATED ISOLATED

+

DETECT

CIRCUIT

POWER SUPPLY

R

D

MAX13412E MAX13413E

LDO

R

t

V

CC

8

7

6

5

B

A

GND

0.1μF

ISO_V

CC

R

t

MAX13410E–MAX13415E

RS-485 Transceiver with Integrated Low-Dropout Regulator and AutoDirection Control

22 ______________________________________________________________________________________

Figure 11. Typical Application Circuit for the MAX13414E/MAX13415E

Figure 12. Using the MAX845 to Obtain an Isolated Power Supply

Figure 13. The MAX5021 and MAX5022 provide an isolated power supply with tighter regulation due to feedback using an opto-isolator coupler.

R

t

ISO_V

MCU AND RELATED

CIRCUITRY

CC

V

SYS

ISO_V

CC

V

SYS

ISO_V

CC

V

SYS

ISO_V

C

S

DE/RE

CC

RO

1

2

V

REG

3

1μF

DI

4

UNREGULATED ISOLATED

POWER SUPPLY

+

R

D

LDO

MAX13414E MAX13415E

V

CC

8

7

6

5

0.1μF

B

A

GND

V

5V

ON / OFF

46

SD

MAX845

3

FREQUENCY

SELECT

GND1 GND2

27

IN

C1

V

CC

1

D1

8

D2FS

CR1

T1

CR2

OUTPUT

5V AT 150mA

C2

C3

R

t

V

SUPPLY

V

OUT

V

IN

V

CC

MAX5021/

MAX5022

OPTO NDRV

CS

GND

MAX13410E–MAX13415E

RS-485 Transceiver with Integrated Low-Dropout

Regulator and AutoDirection Control

______________________________________________________________________________________ 23

Ordering Information/Selector Guide (continued)

Note: All devices operate over the -40°C to +85°C operating temperature range.

+

Denotes a lead(Pb)-free/RoHS-compliant package.

*

EP = Exposed pad.

**

Future product—contact factory for availability.

Pin Configurations (continued)

Chip Information

PROCESS TECHNOLOGY: BiCMOS

PACKAGE TYPE PACKAGE CODE DOCUMENT NO.

8 SO-EP S8E+14

21-0111

Package Information

For the latest package outline information and land patterns, go to www.maxim-ic.com/packages

. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status.

TOP VIEW

*EXPOSED PAD CONNECTED TO GROUND

+

1

RO

2

MAX13412E

3

V

REG

MAX13413E

4

SO

*EP

87V

6

5

CC

BRE

A

GNDDI

V

REG

+

1

RO

2

MAX13414E

3

MAX13415E

4

SO

*EP

87V

6

5

CC

BDE/RE

A

GNDDI

PART PIN-PACKAGE AutoDirection DATA RATE (max) 5V LDO OUTPUT

MAX13412EESA+ 8 SO-EP* Yes 500kbps Yes

MAX13413EESA+ 8 SO-EP* Yes 16Mbps Yes

MAX13414EESA+** 8 SO-EP* No 500 kbps Yes

MAX13415EESA+** 8 SO-EP* No 16Mbps Yes

MAX13410E–MAX13415E

RS-485 Transceiver with Integrated Low-Dropout Regulator and AutoDirection Control

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.

24

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

Revision History

REVISION

NUMBER

0 11/07 Initial release. —

1 8/09 Replaced Figure 9. 20

REVISION

DATE

DESCRIPTION

PAGES

CHANGED

Datasheet MAX13415E Datasheet (MAXIM)

Specifications and Main Features

Frequently Asked Questions

User Manual