LINEAR TECHNOLOGY LTC1484 Technical data

FEATURES

■

No Damage or Latchup to ±15kV ESD (Human
Body Model), IEC-1000-4-2 Level 4 Contact (±8kV)
and Level 3 (±8kV) Air Gap Specifications

■

Guaranteed High Receiver Output State for Floating,
Shorted or Terminated Inputs with No Signal
Present

■

Drives Low Cost Residential Telephone Wires

■

Low Power: ICC = 700µA Max with Driver Disabled

■

ICC = 900µA Max for Driver Enable with No Load

■

20µA Max Quiescent Current in Shutdown Mode

■

Single 5V Supply

■

–7V to 12V Common Mode Range Permits ±7V
Ground Difference Between Devices on the Data Line

■

Power Up/Down Glitch-Free Driver Outputs

■

Up to 32 Transceivers on the Bus

■

Pin Compatible with the LTC485

■

Available in 8-Lead MSOP, PDIP and SO Packages

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APPLICATIO S

■

Battery-Powered RS485/RS422 Applications

■

Low Power RS485/RS422 Transceiver

■

Level Translator

LTC1484

Low Power

RS485 Transceiver

with Receiver Fail-Safe

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DESCRIPTIO

The LTC®1484 is a low power RS485 compatible trans­ceiver. In receiver mode, it offers a fail-safe feature which
guarantees a high receiver output state when the inputs
are left open, shorted together or terminated with no
signal present. No external components are required to
ensure the high receiver output state.

Both driver and receiver feature three-state outputs with
separate receiver and driver control pins. The driver
outputs maintain high impedance over the entire com­mon mode range when three-stated. Excessive power
dissipation caused by bus contention or faults is pre­vented by a thermal shutdown circuit that forces the
driver outputs into a high impedance state.

Enhanced ESD protection allows the LTC1484 to with­stand ±15kV (human body model), IEC-1000-4-2 level 4
(±8kV) contact and level 3 (±8kV) air discharge ESD
without latchup or damage.

The LTC1484 is fully specified over the commercial and
industrial temperature ranges and is available in 8-lead
MSOP, PDIP and SO packages.

, LTC and LT are registered trademarks of Linear Technology Corporation.

TYPICAL APPLICATIO

RS485 Interface

RO1

RE1
DE1

DI1

LTC1484

R

D

B1

A1

V

CC1

120Ω 120Ω

GND1

U

V

CC2

GND2

Driving a 2000 Foot STP Cable

LTC1484

B2

A2

R

D

RO2
RE2
DE2
DI2

1484 TA01

Dl1

B2

A2

RO2

Dl1 ↑↓ DE1 = V
Dl2 = 0 DE2 = 0
RE1 = RE2 = 0

CC

1484 TA01a

1

LTC1484

WW

W

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ABSOLUTE MAXIMUM RATINGS

(Note 1)

Supply Voltage (VCC)............................................... 6.5V

Control Input Voltages ................. –0.3V to (VCC + 0.3V)

Driver Input Voltage ..................... –0.3V to (VCC + 0.3V)

Driver Output Voltages ................................. –7V to 10V

Receiver Input Voltages (Driver Disabled) .. –12V to 14V

Receiver Output Voltage ............... – 0.3V to (VCC + 0.3V)

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PACKAGE/ORDER INFORMATION

ORDER PART

NUMBER

TOP VIEW

RO

1

RE

2

DE

3

DI

4

MS8 PACKAGE

8-LEAD PLASTIC MSOP

T

= 125°C, θJA = 200°C/ W

JMAX

8

V

CC

7

B

6

A

5

GND

LTC1484CMS8 LTC1484CN8

MS8 PART MARKING

LTDX

Junction Temperature .......................................... 125°C

Operating Temperature Range

LTC1484C ......................................... 0°C ≤ TA ≤ 70°C

LTC1484I...................................... –40°C ≤ TA ≤ 85°C

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

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

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ORDER PART

TOP VIEW

RO

1

RE

2

DE

3

DI

N8 PACKAGE
8-LEAD PDIP

T

JMAX

T

JMAX

D

4

= 125°C, θJA = 130°C/ W (N8)
= 125°C, θJA = 135°C/W (S8)

V

8

R

8-LEAD PLASTIC SO

CC

B

7

A

6

GND

5

S8 PACKAGE

NUMBER

LTC1484CS8
LTC1484IN8
LTC1484IS8

S8 PART MARKING

1484
1484I

Consult factory for Military grade parts.

ELECTRICAL CHARACTERISTICS

temperature range, otherwise specifications are at T

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

OD1

V

OD2

V

OD3

∆V

OD

V

OC

∆|VOC| Change in Magnitude of Driver Common Mode R = 22Ω, 27Ω or R = 50Ω, Figure 1 ● 0.2 V

V

IH

V

IL

I

IN1

I

IN2

V

TH

Differential Driver Output Voltage (Unloaded) I
Differential Driver Output Voltage (with Load) R = 50Ω (RS422) ● 2V

Differential Driver Output Voltage V
(with Common Mode)

Change in Magnitude of Driver Differential R = 22Ω, 27Ω or R = 50Ω, Figure 1 ● 0.2 V
Output Voltage for Complementary Output States V

Driver Common Mode Output Voltage R = 22Ω, 27Ω or R = 50Ω, Figure 1 ● 3V

Output Voltage for Complementary Output States
Input High Voltage DE, DI, RE ● 2.0 V
Input Low Voltage DE, DI, RE ● 0.8 V
Input Current DE, DI, RE ● ±2 µA
Input Current (A, B) DE = 0, VCC = 0 or 5V, VIN = 12V ● 1.0 mA

Differential Input Threshold Voltage for Receiver –7V ≤ VCM ≤ 12V, DE = 0 ● –0.20 –0.015 V

The ● denotes the specifications which apply over the full operating

= 25°C. VCC = 5V ±5% (Notes 2 and 3) unless otherwise noted.

A

= 0 ● V

OUT

R = 27Ω (RS485) Figure 1
R = 22Ω, Figure 1

= –7V to 12V, Figure 2 ● 1.5 5 V

TST

= –7V to 12V, Figure 2

TST

DE = 0, V

= 0 or 5V, VIN = –7V ● –0.8 mA

CC

● 1.5 5 V

● 1.5 5 V

CC

V

2

LTC1484

ELECTRICAL CHARACTERISTICS

temperature range, otherwise specifications are at T

The ● denotes the specifications which apply over the full operating

= 25°C. VCC = 5V ±5% (Notes 2 and 3) unless otherwise noted.

A

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

∆V
V
V
I

TH

OH

OL

OZR

Receiver Input Hysteresis VCM = 0V, DE = 0 ● ±30 mV
Receiver Output High Voltage I
Receiver Output Low Voltage I
Three-State (High Impedance) Output Current VCC = Max, 0.4V ≤ V

= –4mA, (VA – VB) = 200mV ● 3.5 V

OUT

= 4mA, (VA – VB) = –200mV ● 0.4 V

OUT

≤ 2.4V, ● ±1 µA

OUT

at Receiver DE = 0

R

IN

I

CC

I

SHDN

I

OSD1

I

OSD2

I

OSR

Receiver Input Resistance –7V ≤ VCM ≤ 12V ● 12 22 kΩ
Supply Current No Load, Output Enabled (DE = VCC) ● 600 900 µA

No Load, Output Disabled (DE = 0)

● 400 700 µA

Supply Current in Shutdown Mode DE = 0, RE = VCC, DI = 0 ● 120 µA
Driver Short-Circuit Current, V
Driver Short-Circuit Current, V
Receiver Short-Circuit Current 0V ≤ V

= High (Note 4) –7V ≤ V

OUT

= Low (Note 4) – 7V ≤ V

OUT

≤ 10V 35 250 mA

OUT

≤ 10V 35 250 mA

OUT

OUT

≤ V

CC

● 785mA

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SWITCHING CHARACTERISTICS

temperature range, otherwise specifications are at T

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

t

PLH

t

PHL

t

SKEW

tr, t

t

ZH

t

ZL

t

LZ

t

HZ

t

PLH

t

PHL

t

SKD

t

ZL

t

ZH

t

LZ

t

HZ

t

DZR

f

MAX

t

SHDN

f

Driver Input to Output R

Driver Input to Output R

Driver Output to Output R

Driver Rise or Fall Time R

Driver Enable to Output High CL = 100pF (Figures 5, 7) S2 Closed ● 40 70 ns
Driver Enable to Output Low CL = 100pF (Figures 5, 7) S1 Closed ● 40 100 ns
Driver Disable Time from Low CL = 15pF (Figures 5, 7) S1 Closed ● 40 70 ns
Driver Disable Time from High CL = 15pF (Figures 5, 7) S2 Closed ● 40 70 ns
Receiver Input to Output R

Receiver Input to Output R

|t

– t

PLH

| Differential Receiver Skew R

PHL

Receiver Enable to Output Low CRL = 15pF (Figures 3, 9) S1 Closed ● 20 50 ns
Receiver Enable to Output High CRL = 15pF (Figures 3, 9) S2 Closed ● 20 50 ns
Receiver Disable from Low CRL = 15pF (Figures 3, 9) S1 Closed ● 20 50 ns
Receiver Disable from High CRL = 15pF (Figures 3, 9) S2 Closed ● 20 50 ns
Driver Enable to Receiver Valid R

Maximum Data Rate (Note 5) ● 4 5 Mbps
Time to Shutdown (Note 6) DE = 0, RE↑ ● 50 300 600 ns

The ● denotes the specifications which apply over the full operating

= 25°C.

A

= 54Ω, CL1 = CL2 = 100pF ● 10 28.5 60 ns

DIFF

(Figures 4, 6)

= 54Ω, CL1 = CL2 = 100pF ● 10 31 60 ns

DIFF

(Figures 4, 6)

= 54Ω, CL1 = CL2 = 100pF ● 2.5 10 ns

DIFF

(Figures 4, 6)

= 54Ω, CL1 = CL2 = 100pF ● 31540 ns

DIFF

(Figures 4, 6)

= 54Ω, CL1 = CL2 = 100pF, ● 30 160 200 ns

DIFF

(Figures 4, 8)

= 54Ω, CL1 = CL2 = 100pF, ● 30 140 200 ns

DIFF

(Figures 4, 8)

= 54Ω, CL1 = CL2 = 100pF, 20 ns

DIFF

(Figures 4, 8)

= 54Ω, CL1 = CL2 = 100pF ● 1600 3000 ns

DIFF

(Figures 4, 10)

3

LTC1484

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SWITCHING CHARACTERISTICS

temperature range, otherwise specifications are at T

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

t

ZH(SHDN)

t

ZL(SHDN)

t

ZH(SHDN)

t

ZL(SHDN)

Driver Enable from Shutdown to Output High CL = 100pF (Figures 5, 7) S2 Closed, ● 40 100 ns

Driver Enable from Shutdown to Output Low CL = 100pF (Figures 5, 7) S1 Closed, ● 40 100 ns

Receiver Enable from Shutdown to Output High CL = 15pF (Figures 3, 9) S2 Closed, ● 10 µs

Receiver Enable from Shutdown to Output Low CL = 15pF (Figures 3, 9) S1 Closed, ● 10 µs

The ● denotes the specifications which apply over the full operating

= 25°C. VCC = 5V ±5% (Notes 2 and 3) unless otherwise noted.

A

DI = DE

DI = 0

DE = 0

DE = 0

Note 1: Absolute Maximum Ratings are those values beyond which the life of
a device may be impaired.

Note 2: All typicals are given for V

= 5V and TA = 25°C.

CC

Note 5: Guaranteed by design.
Note 6: Time for I

Note 3: All currents into device pins are positive; all currents out of device

pins are negative. All voltages are referenced to device ground unless
otherwise specified.

Note 4: For higher ambient temperatures, the part may enter thermal
shutdown during short-circuit conditions.

UW

TYPICAL PERFOR A CE CHARACTERISTICS

Receiver Output Voltage vs Input
Voltage

6

TA = 25°C

= 5V

V

CC

5

4

3

2

1

RECEIVER OUTPUT VOLTAGE (V)

0

–0.2

V

TH(LOW)

–0.16 –0.12 –0.08 –0.04 0

INPUT VOLTAGE (V)

V

TH(HIGH)

1484 G01

Receiver Input Threshold Voltage
(Output High) vs Temperature

0

VCC = 5V
V

–0.05

–0.10

–0.15

–0.20

RECEIVER INPUT THRESHOLD VOLTAGE (V)

–0.25

TH(HIGH)

VCM = –7V

VCM = 0V

–55 –35 –15 5 25 45 65 85 105 125

TEMPERATURE (°C)

VCM = 12V

to drop to ICC/2 when the receiver is disabled.

CC

Receiver Input Threshold Voltage
(Output Low) vs Temperature

0

VCC = 5V
V

TH(LOW)

VCM = 0V

–55 –35 –15 5 25 45 65 85 105 125

TEMPERATURE (°C)

1484 G02

–0.05

–0.10

–0.15

–0.20

RECEIVER INPUT THRESHOLD VOLTAGE (V)

–0.25

VCM = –7V

VCM = 12V

1484 G03

4

UW

TYPICAL PERFOR A CE CHARACTERISTICS

LTC1484

Receiver Input Offset Voltage vs
Temperature

0

VCC = 5V

–20
–40
–60

–80
–100
–120
–140
–160
–180

RECEIVER INPUT OFFSET VOLTAGE (mV)

–200

VCM = 0V

–55 –35 –15 5 25 45 65 85 105 125

TEMPERATURE (°C)

VCM = –7V

VCM = 12V

Receiver Output High Voltage vs
Output Current

5.0
VCC = 4.75V

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

RECEIVER OUTPUT HIGH VOLTAGE (V)

0.5

0

–20 –15 –10 –5 0

–25

OUTPUT CURRENT (mA)

1484 G04

1484 G07

Receiver Hysteresis vs
Temperature

100

VCC = 5V

90
80
70
60

V

50
40
30

RECEIVER HYSTERESIS (mV)

20
10

0

–55 –35 –15 5 25 45 65 85 105 125

TEMPERATURE (°C)

TH(HIGH)

= –7V TO 12V

V

CM

– V

TH(LOW)

Receiver Output Low Voltage vs
Output Current

1.0
VCC = 4.75V

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

RECEIVER OUTPUT LOW VOLTAGE (V)

0.1

0

5 10 15 20 25

0

OUTPUT CURRENT (mA)

Receiver Input Threshold Voltage
vs Supply Voltage

0

TA = 25°C

–0.02
–0.04
–0.06
–0.08

1484 G05

–0.10
–0.12
–0.14
–0.16
–0.18

RECEIVER INPUT THRESHOLD VOLTAGE (V)

–0.20

= 0V

V

CM

V

TH(HIGH)

V

TH(LOW)

4.5 4.75 5 5.25
SUPPLY VOLTAGE (V)

1484 G06

Receiver Output High Voltage vs
Temperature

4.5
VCC = 4.75V

1484 G08

4.4

4.3

4.2

4.1

4.0

3.9

3.8

3.7

RECEIVER OUTPUT HIGH VOLTAGE (V)

3.6

3.5

= –8mA

I

OUT

–55 –35 –15 5 25 45 65 85 105 125

TEMPERATURE (°C)

1484 G09

Receiver Output Low Voltage vs
Temperature

0.50
VCC = 4.75V

0.45

0.40

0.35

0.30

0.25

0.20

0.15

0.10

RECEIVER OUTPUT LOW VOLTAGE (V)

0.05

= 8mA

I

OUT

0

–55 –35 –15 5 25 45 65 85 105 125

TEMPERATURE (°C)

1484 G10

Input Current (A, B) vs
Temperature

600
500
400
300
200

VCC = 0V OR 5V

100

0

–100

INPUT CURRENT (µA)

–200
–300
–400

–55 –35 –15 5 25 45 65 85 105 125

VCM = 12V

VCM = –7V

TEMPERATURE (°C)

1484 G11

Receiver Input Resistance vs
Temperature

26.0
VCC = 0V OR 5V

25.5

25.0

24.5

24.0

23.5

23.0

RECEIVER INPUT RESISTANCE (kΩ)

22.5

22.0

–55 –35 –15 5 25 45 65 85 105 125

TEMPERATURE (°C)

VCM = 12V

VCM = –7V

1484 G12

5