Datasheet

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LTC1480

1480fa

OUTPUT CURRENT (mA)

OUTPUT VOLTAGE (V)

0.5

1.0

1.5

2.0

2.5

60 70 80

1480 TA02

10 20 30 40 50 90

3.0

3.5

= 3.3V

= 25°C

APPLICATIO S

DESCRIPTIO

FEATURES

TYPICAL APPLICATIO

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

All other trademarks are the property of their respective owners.

■

True RS485 from a Single 3.3V Supply

■

Low Power: I

= 500µA Max with Driver Disabled

■

= 600

A Max with Driver Enabled, No Load

■

A Quiescent in Shutdown Mode

■

–7V to 12V Common Mode Range Permits ±7V

Ground Difference Between Devices on the Data Line

■

Thermal Shutdown Protection

■

Power Up/Down Glitch-Free Driver Outputs Permit

Live Insertion or Removal of Transceiver

■

Driver Maintains High Impedance in Three-State or

with the Power Off

■

Up to 32 Transceivers on the Bus

■

50ns Typical Driver Propagation Delays with

10ns Skew

■

Pin Compatible with the LTC485

■

Available in 8-Lead DIP and SO Packages

3.3V Ultralow Power

RS485 Transceiver

The LTC

1480 is an ultralow power differential line trans-

ceiver which provides full RS485 compatibility while oper-

ating from a single 3.3V supply. It is designed for data

transmission standard RS485 applications with extended

common mode range (12V to –7V). It also meets the

requirements of RS422 and features high speed operation

up to 2.5Mb/s. The CMOS design offers significant power

savings without sacrificing ruggedness against overload

or ESD damage. Typical quiescent current is only 300µA

while operating and 1µA in shutdown.

The driver and receiver feature three-state outputs, with

the driver outputs maintaining high impedance over the

entire common mode range. Excessive power dissipation

caused by bus contention or faults is prevented by a

thermal shutdown circuit which forces the driver outputs

into a high impedance state. The receiver has a fail-safe

feature which guarantees a high output state when the

inputs are left open.

The LTC1480 is fully specified over the commercial and

extended industrial temperature range. The LTC1480 is

available in 8-pin SO and DIP packages.

■

Battery-Powered RS485/RS422 Applications

■

Low Power RS485/RS422 Transceiver

■

Level Translator

Driver Differential

Output Voltage vs Output Current

3.3V RS485 Network

1480 TA01

LTC1480

120Ω120Ω

SHIELD SHIELD

3.3V

LTC1480

3.3V

RO RE DE DI

Summary of content (8 pages)

PAGE 1
LTC1480 3.3V Ultralow Power RS485 Transceiver U FEATURES DESCRIPTIO ■ The LTC®1480 is an ultralow power differential line transceiver which provides full RS485 compatibility while operating from a single 3.3V supply. It is designed for data transmission standard RS485 applications with extended common mode range (12V to –7V). It also meets the requirements of RS422 and features high speed operation up to 2.5Mb/s.
PAGE 2
LTC1480 U W W W ABSOLUTE AXI U RATI GS U W U PACKAGE/ORDER I FOR ATIO (Note 1) Supply Voltage (VCC) ................................................ 7V Control Input Voltage ..................... – 0.3V to VCC + 0.3V Driver Input Voltage ....................... – 0.3V to VCC + 0.3V Driver Output Voltage ........................................... ±14V Receiver Input Voltage .......................................... ±14V Receiver Output Voltage ................ – 0.3V to VCC + 0.
PAGE 3
LTC1480 U SWITCHI G CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range. VCC = 3.3V (Notes 2, 3).
PAGE 4
LTC1480 U W TYPICAL PERFORMANCE CHARACTERISTICS Receiver Output Low Voltage vs Output Current Driver Skew vs Temperature 25 7.0 – 16 VCC = 3.3V TA = 25°C VCC = 3.3V 6.5 – 14 5.0 4.5 4.0 OUTPUT CURRENT (mA) OUTPUT CURRENT (mA) 5.5 15 10 5 3.5 – 12 – 10 –8 –6 –4 –2 3.0 – 40 – 20 0 0 40 60 20 TEMPERATURE (°C) 80 100 0 3.30 3.05 2.80 2.55 2.30 2.05 1.80 1.55 1.30 OUTPUT VOLTAGE (V) 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.
PAGE 5
LTC1480 U U FU CTIO TABLES LTC1480 Receiving LTC1480 Transmitting INPUTS INPUTS OUTPUTS RE DE DI B A RE DE X 1 1 0 1 0 OUTPUTS A–B RO 0 ≥ 0.2V 1 0 ≤ – 0.2V 0 X 1 0 1 0 0 0 0 X Z Z 0 0 Inputs Open 1 1 0 X Z* Z* 1 0 X Z* *Shutdown mode *Shutdown mode TEST CIRCUITS A S1 TEST POINT RECEIVER OUTPUT R VCC VOD VOC R 1k 1k CRL S2 B 1480 F02 1480 F01 Figure 1. Driver DC Test Load Figure 2.
PAGE 6
LTC1480 U W W SWITCHI G TI E WAVEFOR S 3V f = 1MHz, tr ≤ 10ns, tf ≤ 10ns 1.5V DE 1.5V 0V t LZ t ZL(SHDN), t ZL 3.3V A, B VOL 2.3V OUTPUT NORMALLY LOW 0.5V 2.3V OUTPUT NORMALLY HIGH 0.5V VOH A, B 0V t HZ t ZH(SHDN), t ZH 1480 F06 Figure 6. Driver Enable and Disable Times VOH 1.5V RO VOL 1.5V OUTPUT f = 1MHz, tr ≤ 10ns, tf ≤ 10ns t PHL VOD2 A–B –VOD2 0V t PLH 0V INPUT 1480 F07 Figure 7. Receiver Propagation Delays 3V 1.5V RE t ZL(SHDN), tZL 3.3V RO VOL t LZ 1.
PAGE 7
LTC1480 U W U U APPLICATIO S I FOR ATIO current from flowing when the common mode voltage exceeds the supply rails. Latch-up at the output drivers is virtually eliminated and the driver is prevented from loading the line under RS485 specified fault conditions. When two or more drivers are connected to the same transmission line, a potential condition exists whereby more than two drivers are simultaneously active.
PAGE 8
LTC1480 U U W U APPLICATIO S I FOR ATIO 100pF BR TTL IN t r, t f < 6ns D RECEIVER OUT R R 100Ω 1480 F11 100pF Figure 11. Receiver Propagation Delay Test Circuit U PACKAGE DESCRIPTIO N8 Package 8-Lead PDIP (Narrow .300 Inch) (Reference LTC DWG # 05-08-1510) .008 – .015 (0.203 – 0.381) ( +.035 .325 –.015 8.255 +0.889 –0.381 NOTE: 1. DIMENSIONS ARE .130 ± .005 (3.302 ± 0.127) .045 – .065 (1.143 – 1.651) .300 – .325 (7.620 – 8.255) .065 (1.651) TYP ) .120 (3.048) .020 MIN (0.508) MIN .