ANALOG DEVICES LT 1785 IS8 Datasheet

LT1785/LT1785A/

LT1791/LT1791A

60V Fault Protected

RS485/RS422 Transceivers

FeaTures

n

Protected from Overvoltage Line Faults to ±60V

n

Pin Compatible with LTC485 and LTC491

n

High Input Impedance Supports Up to 128 Nodes

n

No Damage or Latchup to ESD

n

IEC-1000-4-2 Level 4: ±15kV Air Discharge

n

IEC-1000-4-2 Level 2: ±4kV Contact Discharge

n

Controlled Slew Rates for EMI Emissions Control

n

Guaranteed High Receiver Output State for Floating,

Shorted or Inactive Inputs (LT1785A/LT1791A)

n

Outputs Assume a High Impedance When Off or

Powered Down

n

Drives Low Cost, Low Impedance Cables

n

Short-Circuit Protection on All Outputs

n

Thermal Shutdown Protection

n

Guaranteed Operation to 125°C

applicaTions

n

Industrial Control Data Networks

n

CAN Bus Applications

n

HVAC Controls

L, LT, LTC, LTM, µModule, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.

DescripTion

The LT®1785/LT1791 are half-duplex and full-duplex differ- ential bus transceivers for RS485 and RS422 applications which feature on-chip protection from overvoltage faults on the data transmission lines. Receiver input and driver output pins can withstand voltage faults up to ±60V with respect to ground with no damage to the device. Faults may occur while the transceiver is active, shut down or powered off.

rates to 250kbaud on networks of up to 128 nodes

Data are supported. Controlled slew rates on the driver out putscontrol EMI emissions and improve data transmission integrity on improperly terminated lines. Drivers are speciﬁed to operate with inexpensive cables

as low as

72Ω characteristic impedance.

The LT1785A/LT1791A devices have “fail-safe” receiver inputs to guarantee a receiver output high for shorted, open or inactive data lines. On-chip ESD protection eliminates need for external protection devices.

The LT1785/LT1785A are available in 8-lead DIP and SO packages and the LT1791/LT1791A in 14-lead DIP and SO packages.

-

Typical applicaTion

V

RO1

RE1

DE1

DI1

RO2

RE2

DE2

DI2

RX

LT1785

TX

RX

LT1785

TX

CC1

GND1

V

CC2

GND2

R

TERM

Normal Operation Waveforms at 250kBaud

RO

Y-Z

DI

178591 TA01

For more information www.linear.com/LT1785

178591 TA02

178591fd

1

LT1785/LT1785A/

TOP VIEW

LT1791/LT1791A

absoluTe MaxiMuM raTings

(Note 1)

Supply Voltage (VCC) ................................................18V

Receiver Enable Input Voltage ...................... –0.3V to 6V

Driver Enable Input Voltage .......................... –0.3V to 6V

Driver Input Voltage ................................... –0.3V to 18V

Receiver Input Voltage ................................ –60V to 60V

Driver Output Voltage .................................. –60V to 60V

Receiver Output Voltage ...................–0.3V to (V

+ 6V)

CC

pin conFiguraTion

RO

1

2

3

4

R

D

8-LEAD PLASTIC SO

RE

DE

DI

N8 PACKAGE 8-LEAD PDIP

= 150°C, θJA = 130°C/W (N8)

T

JMAX

= 150°C, θJA = 150°C/W (S8)

T

JMAX

V

8

B

7

A

6

GND

5

S8 PACKAGE

CC

Operating Temperature Range LT1785C/LT1791C/

LT1785AC/LT1791AC .................................... 0°C to 70°C

LT1785I/LT1791I/

LT1785AI/LT1791AI .................................. –40°C to 85°C

LT1785H/LT1791H/

LT1785AH/LT1791AH ............................. –40°C to 125°C

Storage Temperature Range ...................–65°C to 150°C

Lead Temperature (Soldering, 10 sec) .................. 300°C

1

NC

2

RO

3

RE

4

DE

5

DI

6

GND

7

GND

N PACKAGE

14-LEAD PDIP

= 150°C, θJA = 130°C/W (N)

T

JMAX

= 150°C, θJA = 150°C/W (S)

T

JMAX

14

V

CC

R

13

NC

12

A

11

B

10

9

8

S PACKAGE

Z

Y

NC

D

14-LEAD PLASTIC SO

orDer inForMaTion

LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE

LT1785CN8#PBF LT1785CN8#TRPBF 1785 8-Lead PDIP 0°C to 70°C

LT1785CS8#PBF LT1785CS8#TRPBF 1785 8-Lead Plastic SO 0°C to 70°C

LT1785IN8#PBF LT1785IN8#TRPBF 1785I 8-Lead PDIP –40°C to 85°C

LT1785IS8#PBF LT1785IS8#TRPBF 1785I 8-Lead Plastic SO –40°C to 85°C

LT1785ACN8#PBF LT1785ACN8#TRPBF 1785A 8-Lead PDIP 0°C to 70°C

LT1785ACS8#PBF LT1785ACS8#TRPBF 1785A 8-Lead Plastic SO 0°C to 70°C

LT1785AIN8#PBF LT1785AIN8#TRPBF 1785AI 8-Lead PDIP –40°C to 85°C

LT1785AIS8#PBF LT1785AIS8#TRPBF 1785AI 8-Lead Plastic SO –40°C to 85°C

LT1785HN8#PBF LT1785HN8#TRPBF 1785H 8-Lead PDIP –40°C to 125°C

LT1785HS8#PBF LT1785HS8#TRPBF 1785H 8-Lead Plastic SO –40°C to 125°C

LT1785AHN8#PBF LT1785AHN8#TRPBF 1785AH 8-Lead PDIP –40°C to 125°C

LT1785AHS8#PBF LT1785AHS8#TRPBF 1785AH 8-Lead Plastic SO –40°C to 125°C

LT1791CN#PBF LT1791CN#TRPBF 1791 14-Lead PDIP 0°C to 70°C

LT1791CS#PBF LT1791CS#TRPBF 1791 14-Lead Plastic SO 0°C to 70°C

2

For more information www.linear.com/LT1785

178591fd

LT1785/LT1785A/

LT1791/LT1791A

orDer inForMaTion

LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE

LT1791IN#PBF LT1791IN#TRPBF 1791I 14-Lead PDIP –40°C to 85°C

LT1791IS#PBF LT1791IS#TRPBF 1791I 14-Lead Plastic SO –40°C to 85°C

LT1791ACN#PBF LT1791ACN#TRPBF 1791A 14-Lead PDIP 0°C to 70°C

LT1791ACS#PBF LT1791ACS#TRPBF 1791A 14-Lead Plastic SO 0°C to 70°C

LT1791AIN#PBF LT1791AIN#TRPBF 1791AI 14-Lead PDIP –40°C to 85°C

LT1791AIS#PBF LT1791AIS#TRPBF 1791AI 14-Lead Plastic SO –40°C to 85°C

LT1791HN#PBF LT1791HN#TRPBF 1791H 14-Lead PDIP –40°C to 125°C

LT1791HS#PBF LT1791HS#TRPBF 1791H 14-Lead Plastic SO –40°C to 125°C

LT1791AHN#PBF LT1791AHN#TRPBF 1791AH 14-Lead PDIP –40°C to 125°C

LT1791AHS#PBF LT1791AHS#TRPBF 1791AH 14-Lead Plastic SO –40°C to 125°C

LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE

LT1785CN8 LT1785CN8#TR 1785 8-Lead PDIP 0°C to 70°C

LT1785CS8 LT1785CS8#TR 1785 8-Lead Plastic SO 0°C to 70°C

LT1785IN8 LT1785IN8#TR 1785I 8-Lead PDIP –40°C to 85°C

LT1785IS8 LT1785IS8#TR 1785I 8-Lead Plastic SO –40°C to 85°C

LT1785ACN8 LT1785ACN8#TR 1785A 8-Lead PDIP 0°C to 70°C

LT1785ACS8 LT1785ACS8#TR 1785A 8-Lead Plastic SO 0°C to 70°C

LT1785AIN8 LT1785AIN8#TR 1785AI 8-Lead PDIP –40°C to 85°C

LT1785AIS8 LT1785AIS8#TR 1785AI 8-Lead Plastic SO –40°C to 85°C

LT1785HN8 LT1785HN8#TR 1785H 8-Lead PDIP –40°C to 125°C

LT1785HS8 LT1785HS8#TR 1785H 8-Lead Plastic SO –40°C to 125°C

LT1785AHN8 LT1785AHN8#TR 1785AH 8-Lead PDIP –40°C to 125°C

LT1785AHS8 LT1785AHS8#TR 1785AH 8-Lead Plastic SO –40°C to 125°C

LT1791CN LT1791CN#TR 1791 14-Lead PDIP 0°C to 70°C

LT1791CS LT1791CS#TR 1791 14-Lead Plastic SO 0°C to 70°C

LT1791IN LT1791IN#TR 1791I 14-Lead PDIP –40°C to 85°C

LT1791IS LT1791IS#TR 1791I 14-Lead Plastic SO –40°C to 85°C

LT1791ACN LT1791ACN#TR 1791A 14-Lead PDIP 0°C to 70°C

LT1791ACS LT1791ACS#TR 1791A 14-Lead Plastic SO 0°C to 70°C

LT1791AIN LT1791AIN#TR 1791AI 14-Lead PDIP –40°C to 85°C

LT1791AIS LT1791AIS#TR 1791AI 14-Lead Plastic SO –40°C to 85°C

LT1791HN LT1791HN#TR 1791H 14-Lead PDIP –40°C to 125°C

LT1791HS LT1791HS#TR 1791H 14-Lead Plastic SO –40°C to 125°C

LT1791AHN LT1791AHN#TR 1791AH 14-Lead PDIP –40°C to 125°C

LT1791AHS LT1791AHS#TR 1791AH 14-Lead Plastic SO –40°C to 125°C

Consult LTC Marketing for parts speciﬁed with wider operating temperature ranges. *The temperature grade is identiﬁed by a label on the shipping container. For more information on lead free part marking, go to: http://www.linear.com/leadfree/

This product is only offered in trays. For more information go to: http://www.linear.com/packaging/

For more information www.linear.com/LT1785

178591fd

3

LT1785/LT1785A/ LT1791/LT1791A

Dc elecTrical characTerisTics

The l denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TA = 25°C, VCC = 5V.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

OD1

V

OD2

V

OD

Differential Driver Output Voltage (Unloaded) IO = 0

Differential Driver Output Voltage (With Load) R = 50Ω (RS422), Figure 1

Change in Magnitude of Driver Differential Output Voltage for Complementary Output States

V

∆|V

OC

Driver Common Mode Output Voltage R = 27Ω or R = 50Ω, Figure 1

| Change in Magnitude of Driver Common Mode Output

OC

Voltage for Complementary Output States

V

I

V

∆V

V

IH

IL

IN1

IN2

TH

OH

OL

Input High Voltage DI, DE, RE Input Low Voltage DI, DE, RE Input Current DI, DE, RE

Input Current (A, B); (LT1791 or LT1785 with DE = 0V) VIN = 12V

Differential Input Threshold Voltage for Receiver LT1785/LT1791: –7V ≤ VCM ≤ 12V

Receiver Input Hysteresis –7V < VCM < 12V 20 mV

TH

Receiver Output High Voltage IO = –400µA, VID = 200mV

Receiver Output Low Voltage IO = 1.6mA, VID = –200mV

Three-State (High Impedance) Output Current at Receiver 0V < V

R

IN

Receiver Input Resistance (LT1791) –7V ≤ VCM ≤ 12V

OUT

< 6V

LT1785 –7V ≤ V

RS485 Unit Load 0.25

I

SC

Driver Short-Circuit Current V

Driver Output Fault Current V

Receiver Short-Circuit Current 0V ≤ V

Driver Three-State Output Current –7V ≤ V

I

CC

Supply Current No Load, RE = 0V, DE = 5V

R = 27Ω (RS485), Figure 1 R = 18Ω

R = 27Ω or R = 50Ω, Figure 1

V

= –7V

IN

–60V ≤ V

LT1785A/LT1791A: –7V ≤ V

≤ 60V

IN

CM

RE > 2V or Power Off

– 60V ≤ V

OUT

V

OUT

= 60V

O

V

= –60V

O

–60V ≤ V

≤ 60V

CM

≤ 12V

CM

= HIGH, Force VO = –7V = LOW, Force VO = 12V

≤ V

O

CC

≤ 12V

O

≤ 60V

O

No Load, RE = 5V, DE = 5V No Load, RE = 0V, DE = 0V No Load, RE = 5V, DE = 0V

≤ 12V

l

2.0

l

1.5

l

1.2

l

2 2.5 3 V

l

2 V

l

l l

–0.15

l

–6

l

–0.2

l

–0.2

l

3.5 4 V

l

–1 1 µA

l

85 125

4.1 5 V

2.70

2.45

2.2

0.15

–0.08

0.3 0.5 V

125

l

50 90 kΩ

l

35

l

35

l l

–6

l

–0.2

l

–6

l l l l

5.5

4.5

0.2

0.2 V

0.8 V

5 µA

0.3

6

mA mA mA

0.2 0

kΩ kΩ

250 250

mA mA

6 mA

mA

±35 mA

0.3 6

9 9 8

0.3

mA mA

mA mA mA mA

V V V

V V

4

178591fd

For more information www.linear.com/LT1785

LT1785/LT1785A/

LT1791/LT1791A

swiTching characTerisTics

The l denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TA = 25°C, VCC = 5V.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

t

PLH

t

PHL

t

SKEW

, t

t

r

f

t

ZH

t

ZL

t

LZ

t

HZ

t

PLH

t

PHL

t

SKD

t

ZL

t

ZH

t

LZ

t

HZ

f

MAX

t

SHDN

t

ZH(SHDN)

t

ZL(SHDN)

t

ZH(SHDN)

t

ZL(SHDN)

Driver Input to Output Figures 3, 5

Driver Output to Output Figures 3, 5 100 ns

Driver Rise or Fall Time Figures 3, 5

Driver Enable to Output High Figures 4, 6

Driver Enable to Output Low Figures 4, 6

Driver Disable Time from Low Figures 4, 6

Driver Disable Time from High Figures 4, 6

Receiver Input to Output Figures 3, 7

Differential Receiver Skew 200 ns

Receiver Enable to Output Low Figures 2, 8

Receiver Enable to Output High Figures 2, 8

Receiver Disable from Low Figures 2, 8

Receiver Disable from High Figures 2, 8

Maximum Data Rate

Time to Shut Down Figures 2, 6, 8 3 µs Driver Enable from Shutdown to Output High Figures 2, 6; RE = 5V 12 µs Driver Enable from Shutdown to Output Low Figures 2, 6; RE = 5V 12 µs

Receiver Enable from Shutdown to Output High Figures 2, 8; DE = 0V 4 µs

Receiver Enable from Shutdown to Output Low Figures 2, 8; DE = 0V 4 µs

l

200 800 2000 ns

l

250 kbps

700 2000 ns

500 3000 ns

800 3000 ns

200 5000 ns

800 5000 ns

400 900 ns

300 1000 ns

400 1000 ns

Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime.

178591fd

For more information www.linear.com/LT1785

5

LT1785/LT1785A/

OUTPUT VOLTAGE (V)

4

DIFFERENTIAL VOLTAGE (V)

3.0

DELAY (ns)

1000

I

(mA)

7

700

LT1791/LT1791A

Typical perForMance characTerisTics

Driver Differential Output Voltage vs Load Resistance

TA = 25°C

3

2

1

0

10

100 1k

LOAD RESISTANCE (Ω)

Driver Propagation Delay vs Temperature

900

800

700

600

500

400

300

PROPAGATION DELAY (ns)

200

100

0

–40

–20

LH

HL

0

TEMPERATURE (°C)

40

20

Driver Differential Output Voltage vs Temperature

2.5

2.0

1.5

1.0

0.5

R = 27Ω

178591 G01

0

–40

–20

0

TEMPERATURE (°C)

40

20

60

80

178591 G02

100

LT1791 Driver Output Leakage DE = 0V

1mA/DIV

–60V

80

178591 G04

100

60

V

IN

178591 G05

200µA/DIV

60V

Receiver Propagation Delay vs Temperature

t

800

600

400

200

0

–40

–20

PHL

t

PLH

40

20

0

TEMPERATURE (°C)

LT1791 Receiver Input Current vs V

IN

–60V

V

IN

80

178591 G03

178591 G06

100

60V

60

LT1785 Input Characteristics Pins A or B; DE = RE = 0V

1mA/DIV

–60V

6

Supply Current vs Temperature

DRIVER AND

6

RECEIVER ON

5

RECEIVER ONLY

4

CC

3

2

V

, V

A

B

60V

178591 G07

1

0

–40

STANDBY

–20

0

TEMPERATURE (°C)

40

20

80

178591 G08

100

60

Receiver Propagation Delay vs Differential Input Voltage

600

500

400

300

DELAY (ns)

LH VCM = 12V

200

100

0

HL VCM = 12V

1

VIN DIFFERENTIAL (V)

HL VCM = –7V

LH VCM = –7V

2

3 4

5

178591 G09

178591fd

For more information www.linear.com/LT1785

ANALOG DEVICES LT 1785 IS8 Datasheet

Specifications and Main Features

Frequently Asked Questions

User Manual

DescripTion

Typical applicaTion

absoluTe MaxiMuM raTings

pin conFiguraTion