NSC DS36C279MX, DS36C279M, DS36C279TN, DS36C279TMX, DS36C279TM Datasheet

DS36C279
Low Power EIA-RS-485 Transceiver with Sleep Mode

General Description

The DS36C279 is a low power differential bus/line trans­ceiver designed to meet the requirements of RS-485 Stan­dard formultipoint data transmission. In addition it is compat­ible with TIA/EIA-422-B.

The sleep mode feature automatically puts the device in a
power saving mode when both the driver and receiver are
disabled.

††

The device is ideal for use in power conscious
applications where the device may be disabled for extended
periods of time.

The driver and receiver outputs feature TRI-STATE

®

capabil­ity.The driver outputs operate over the entire common mode
range of −7V to +12V.Bus contention or fault situations that
cause excessive power dissipation within the device are
handled by a thermal shutdown circuit, which forces the
driver outputs into a high impedance state.

The receiver incorporates a fail safe circuit which guarantees
a high output state when the inputs are left open.

†

The DS36C279T is fully specified over the industrial tem­perature range (−40˚C to +85˚C).

Features

n 100%RS-485 compliant

— Guaranteed RS-485 device interoperation

n Low power CMOS design: I

CC

500 µA max

n Automatic sensing sleep mode

— Reduces I

CC

to 10 µA maximum

n Built-in power up/down glitch-free circuitry

— Permits live transceiver intersection/displacement

n DIP and SOIC packages available
n Industrial temperature range: −40˚C to +85˚C
n On-board thermal shutdown circuitry

— Prevents damage to the device in the event of

excessive power dissipation

n Wide common mode range: −7V to +12V
n Receive open input fail-safe (Note 1)

n

1

⁄4unit load (DS36C279): ≥ 128 nodes

n

1

⁄2unit load (DS36C279T): ≥ 64 nodes

n ESD (Human Body Model): ≥ 2kV
n Drop-in replacement for:

— LTC485 MAX485 DS75176 DS3695

Connection and Logic Diagram Truth Table

DRIVER SECTION

RE* DE DI DO/RI DO*/RI*

XHH H L
XHL L H
XLX Z Z

RECEIVER SECTION

RE* DE RI-RI* RO

LL ≥+0.2V H
LL ≤−0.2V L
H L X Z (Note 2)
L L OPEN (Note 1) H

Note 1: Non-terminated, open input only
Note 2: Device enters sleep mode if enable conditions are held 600 ns

TRI-STATE®is a registered trademark of National Semiconductor Corporation.

DS012053-1

Order Number DS36C279M, DS36C279N,

DS36C279TM or DS36C279TN

See NS Package Number M08A or N08E

July 1998

DS36C279 Low Power EIA-RS-485 Transceiver with Sleep Mode

© 1999 National Semiconductor Corporation DS012053 www.national.com

Absolute Maximum Ratings (Note 3)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.

Supply Voltage (V

CC

) +12V

Input Voltage (DE, RE*, & DI) −0.5V to (V

CC

+0.5V)

Common Mode (V

CM

)

Driver Output/Receiver Input

±

15V

Input Voltage (DO/RI, DO*/RI*)

±

14V

Receiver Output Voltage −0.5V to (V

CC

+0.5V)

Maximum Package Power Dissipation

@

+25˚C
M Package 1190 mW, derate 9.5 mW/˚C above +25˚C
N Package 744 mW, derate 6.0 mW/˚C above +25˚C

Storage Temperature Range −65˚C to +150˚C
Lead Temperature

(Soldering 4 sec) +260˚C

Recommended Operating
Conditions

Min Typ Max Units

Supply Voltage (V

CC

) +4.75 +5.0 +5.25 V
Bus Voltage −7 +12 V
Operating Free Air Temperature (T

A

)
DS36C279T −40 +25 +85 ˚C
DS36C279 0 +25 +70 ˚C

Electrical Characteristics (Notes 4, 5)

Over Supply Voltage and Operating Temperature ranges, unless otherwise specified

Symbol Parameter Conditions Reference Min Typ Max Units

DIFFERENTIAL DRIVER CHARACTERISTICS

V

OD1

Differential Output Voltage IO= 0 mA (No Load) (422)

(485)

1.5 5.0 V

V

OD0

Output Voltage IO= 0 mA 0 5.0 V

V

OD0*

Output Voltage (Output to GND) 0 5.0 V

V

OD2

Differential Output Voltage RL=50Ω (422)

Figure 1

2.0 2.8 V

(Termination Load) R

L

=27Ω (485) 1.5 2.3 5.0 V

∆V

OD2

Balance of V

OD2

RL=27Ωor 50Ω (Note 6) −0.2 0.1 +0.2 V

|V

OD2−VOD2*

| (422, 485)

V

OD3

Differential Output Voltage R1 = 54Ω,R2=375Ω

Figure 2

1.5 2.0 5.0 V

(Full Load) V

TEST

= −7V to +12V

V

OC

Driver Common Mode RL=27Ω (485)

Figure 1

0 3.0 V

Output Voltage R

L

=50Ω (422) 0 3.0 V

∆V

OC

Balance of V

OC

RL=27Ωor (Note 6) −0.2 +0.2 V

|V

OC−VOC*

|R

L

=50Ω (422, 485)

I

OSD

Driver Output Short-Circuit VO= +12V (485)

Figure 4

200 +250 mA

Current V

O

= −7V (485) −190 −250 mA

RECEIVER CHARACTERISTICS

V

TH

Differential Input High
Threshold Voltage

VO=VOH,IO= −0.4 mA

(Note 7)

(422, 485)

+0.035 +0.2 V

−7V ≤ V

CM

≤ +12V

V

TL

Differential Input Low
Threshold Voltage

VO=VOL,IO= 0.4 mA −0.2 −0.035 V

−7V ≤ V

CM

≤ +12V

V

HST

Hysteresis VCM= 0V (Note 8) 70 mV

R

IN

Input Resistance −7V ≤ VCM≤ +12V DS36C279T 24 68 kΩ

DS36C279 48 68 kΩ

I

IN

Line Input Current Other Input = 0V, DS36C279 VIN= +12V 0 0.19 0.25 mA
(Note 9) DE = V

IL

,RE*=VIL,V

IN

= −7V 0 −0.1 −0.2 mA

V

CC

= 4.75 to 5.25 DS36C279T VIN= +12V 0 0.19 0.5 mA

or 0V V

IN

= −7V 0 −0.1 −0.4 mA

I

ING

Line Input Current Glitch Other Input = 0V,

DE=V

IL

,RE*=VIL,

DS36C279 V

IN

= +12V 0 0.19 0.25 mA

(Note 9) V

IN

= −7V 0 −0.1 −0.2 mA

V

CC

= +3.0V or 0V,

T

A

= 25˚C

DS36C279T V

IN

= +12V 0 0.19 0.5 mA

V

IN

= −7V 0 −0.1 −0.4 mA

I

B

Input Balance Test RS = 500Ω (422) (Note 12)

±

400 mV

V

OH

High Level Output Voltage IOH= −4 mA, VID= +0.2V RO

Figure 11

3.5 4.6 V

V

OL

Low Level Output Voltage IOL= +4 mA, VID= −0.2V 0.3 0.5 V

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Electrical Characteristics (Notes 4, 5) (Continued)

Over Supply Voltage and Operating Temperature ranges, unless otherwise specified

Symbol Parameter Conditions Reference Min Typ Max Units

RECEIVER CHARACTERISTICS

I

OSR

Short Circuit Current VO= GND RO 7 35 85 mA

I

OZR

TRI-STATE Leakage
Current

VO= 0.4V to 2.4V

±

1µA

DEVICE CHARACTERISTICS

V

IH

High Level Input Voltage DE,

RE*,

DI

2.0 V

CC

V

V

IL

Low Level Input Voltage GND 0.8 V

I

IH

High Level Input Current VIH=V

CC

2µA

I

IL

Low Level Input Current VCC=5V VIL=0V −2 µA

V

CC

= +3.0V −2 µA

I

CC

Power Supply Current
(No Load)

Driver and Receiver ON

V

CC

200 500 µA

I

CCR

Driver OFF, Receiver ON 200 500 µA

I

CCD

Driver ON, Receiver OFF 200 500 µA

I

CCX

Sleep Mode 0.2 10 µA

Switching Characteristics (Notes 5, 10)

Over Supply Voltage and Operating Temperature ranges, unless otherwise specified

Symbol Parameter Conditions Reference Min Typ Max Units
DRIVER CHARACTERISTICS

t

PHLD

Differential Propagation
Delay High to Low

RL=54Ω,CL= 100 pF

Figures 5, 6

10 39 80 ns

t

PLHD

Differential Propagation
Delay Low to High

10 40 80 ns

t

SKD

Differential Skew 0 1 10 ns
|t

PHLD−tPLHD

|

t

r

Rise Time 32550 ns

t

f

Fall Time 32550 ns

t

PHZ

Disable Time High to Z CL=15pF

RE*=L

Figures 7, 8

80 200 ns

t

PLZ

Disable Time Low to Z

Figures 9, 10

80 200 ns

t

PZH

Enable Time Z to High CL= 100 pF

RE*=L

Figures 7, 8

50 200 ns

t

PZL

Enable Time Z to Low

Figures 9, 10

65 200 ns

t

PSH

Driver Enable from Sleep CL= 100 pF

Figures 7, 8

70 98 250 ns

Mode to Output High (Note 11)

t

PSL

Driver Enble from Sleep CL= 100 pF

Figures 9, 10

70 98 250 ns

Mode to Output Low (Note 11)

RECEIVER CHARACTERISTICS

t

PHL

Propagation Delay CL=15pF

Figures 12, 13

30 210 400 ns

High to Low

t

PLH

Propagation Delay 30 190 400 ns
Low to High

t

SK

Skew, |t

PHL−tPLH

| 0 20 50 ns

t

PLZ

Output Disable Time CL=15pF

Figures 14, 15,

16

50 150 ns

t

PHZ

DE = H 55 150 ns

t

PZL

Output Enable Time 40 150 ns

t

PZH

45 150 ns

t

PSH

Receiver Enable from Sleep CL=15pF

Figures 14, 16

70 97 250 ns

Mode to Output High (Note 11)

t

PSL

Receiver Enable from Sleep CL=15pF

Figures 14, 15

70 95 250 ns

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